Subjects -> TRANSPORTATION (Total: 214 journals)
    - AIR TRANSPORT (9 journals)
    - AUTOMOBILES (26 journals)
    - RAILROADS (10 journals)
    - ROADS AND TRAFFIC (9 journals)
    - SHIPS AND SHIPPING (43 journals)
    - TRANSPORTATION (117 journals)

TRANSPORTATION (117 journals)                     

Showing 1 - 53 of 53 Journals sorted alphabetically
Accident Analysis & Prevention     Hybrid Journal   (Followers: 131)
Analytic Methods in Accident Research     Hybrid Journal   (Followers: 8)
Applied Mobilities     Hybrid Journal   (Followers: 5)
Asian Transport Studies     Open Access   (Followers: 1)
Botswana Journal of Technology     Full-text available via subscription   (Followers: 1)
Case Studies on Transport Policy     Hybrid Journal   (Followers: 13)
Cities in the 21st Century     Open Access   (Followers: 17)
Communications in Transportation Research     Open Access  
Danish Journal of Transportation Research / Dansk Tidsskrift for Transportforskning     Open Access   (Followers: 1)
Decision Making : Applications in Management and Engineering     Open Access   (Followers: 1)
Economics of Transportation     Partially Free   (Followers: 16)
Emission Control Science and Technology     Hybrid Journal   (Followers: 1)
eTransportation     Open Access   (Followers: 1)
EURO Journal of Transportation and Logistics     Open Access   (Followers: 12)
European Journal of Transport and Infrastructure Research (EJTIR)     Open Access   (Followers: 6)
European Transport Research Review     Open Access   (Followers: 22)
Geosystem Engineering     Hybrid Journal  
IATSS Research     Open Access  
IEEE Open Journal of Intelligent Transportation Systems     Open Access   (Followers: 4)
IEEE Vehicular Technology Magazine     Full-text available via subscription   (Followers: 7)
IET Electrical Systems in Transportation     Open Access   (Followers: 13)
IET Intelligent Transport Systems     Open Access   (Followers: 11)
IET Smart Cities     Open Access  
IFAC-PapersOnLine     Open Access  
International Journal of Applied Logistics     Full-text available via subscription   (Followers: 5)
International Journal of Crashworthiness     Hybrid Journal   (Followers: 11)
International Journal of Electric and Hybrid Vehicles     Hybrid Journal   (Followers: 8)
International Journal of Heavy Vehicle Systems     Hybrid Journal   (Followers: 6)
International Journal of Intelligent Transportation Systems Research     Hybrid Journal   (Followers: 13)
International Journal of Mobile Communications     Hybrid Journal   (Followers: 8)
International Journal of Ocean Systems Management     Hybrid Journal   (Followers: 1)
International Journal of Physical Distribution & Logistics Management     Hybrid Journal   (Followers: 11)
International Journal of Services Technology and Management     Hybrid Journal   (Followers: 1)
International Journal of Sustainable Transportation     Hybrid Journal   (Followers: 18)
International Journal of Traffic and Transportation Engineering     Open Access   (Followers: 12)
International Journal of Transportation Engineering     Open Access   (Followers: 2)
International Journal of Transportation Science and Technology     Open Access   (Followers: 9)
International Journal of Vehicle Systems Modelling and Testing     Hybrid Journal   (Followers: 2)
Journal of Advanced Transportation     Hybrid Journal   (Followers: 12)
Journal of Big Data Analytics in Transportation     Hybrid Journal   (Followers: 2)
Journal of Intelligent and Connected Vehicles     Open Access   (Followers: 1)
Journal of Mechatronics, Electrical Power, and Vehicular Technology     Open Access   (Followers: 6)
Journal of Modern Transportation     Full-text available via subscription   (Followers: 7)
Journal of Navigation     Hybrid Journal   (Followers: 184)
Journal of Public Transportation     Open Access  
Journal of Sport & Social Issues     Hybrid Journal   (Followers: 10)
Journal of Supply Chain Management Science (JSCMS)     Open Access   (Followers: 7)
Journal of Traffic and Transportation Engineering (English Edition)     Open Access   (Followers: 4)
Journal of Transport & Health     Hybrid Journal   (Followers: 12)
Journal of Transport and Land Use     Open Access   (Followers: 27)
Journal of Transport and Supply Chain Management     Open Access   (Followers: 10)
Journal of Transport Geography     Hybrid Journal   (Followers: 22)
Journal of Transport History     Hybrid Journal   (Followers: 12)
Journal of Transportation and Logistics     Open Access   (Followers: 3)
Journal of Transportation Safety & Security     Hybrid Journal   (Followers: 9)
Journal of Transportation Security     Hybrid Journal   (Followers: 3)
Journal of Transportation Technologies     Open Access   (Followers: 13)
Journal of Waterway Port Coastal and Ocean Engineering     Full-text available via subscription   (Followers: 7)
Journal on Vehicle Routing Algorithms     Hybrid Journal  
Les Dossiers du Grihl     Open Access   (Followers: 1)
LOGI ? Scientific Journal on Transport and Logistics     Open Access  
Logistics     Open Access   (Followers: 1)
Logistics & Sustainable Transport     Open Access   (Followers: 4)
Logistique & Management     Hybrid Journal  
Maritime Transport Research     Open Access  
Mobility in History     Full-text available via subscription   (Followers: 7)
Modern Transportation     Open Access   (Followers: 11)
Nonlinear Dynamics     Hybrid Journal   (Followers: 20)
Open Journal of Safety Science and Technology     Open Access   (Followers: 16)
Open Transportation Journal     Open Access   (Followers: 1)
Packaging, Transport, Storage & Security of Radioactive Material     Hybrid Journal   (Followers: 2)
Periodica Polytechnica Transportation Engineering     Open Access  
Pervasive and Mobile Computing     Hybrid Journal   (Followers: 8)
Proceedings of the Institution of Mechanical Engineers Part F: Journal of Rail and Rapid Transit     Hybrid Journal   (Followers: 11)
Promet : Traffic &Transportation     Open Access  
Public Transport     Hybrid Journal   (Followers: 18)
Recherche Transports Sécurité     Hybrid Journal   (Followers: 1)
Research in Transportation Business and Management     Partially Free   (Followers: 4)
Revista Transporte y Territorio     Open Access  
Romanian Journal of Transport Infrastructure     Open Access   (Followers: 1)
Sport, Education and Society     Hybrid Journal   (Followers: 12)
Sport, Ethics and Philosophy     Hybrid Journal   (Followers: 2)
Streetnotes     Open Access   (Followers: 2)
Synthesis Lectures on Mobile and Pervasive Computing     Full-text available via subscription   (Followers: 1)
Transactions on Transport Sciences     Open Access   (Followers: 4)
Transport     Open Access   (Followers: 16)
Transport and Telecommunication     Open Access   (Followers: 4)
Transport in Porous Media     Hybrid Journal  
Transport Problems     Open Access   (Followers: 4)
Transport Reviews: A Transnational Transdisciplinary Journal     Hybrid Journal   (Followers: 11)
Transportation     Hybrid Journal   (Followers: 32)
Transportation Engineering     Open Access   (Followers: 1)
Transportation Geotechnics     Full-text available via subscription   (Followers: 1)
Transportation in Developing Economies     Hybrid Journal  
Transportation Infrastructure Geotechnology     Hybrid Journal   (Followers: 8)
Transportation Journal     Full-text available via subscription   (Followers: 16)
Transportation Letters : The International Journal of Transportation Research     Hybrid Journal   (Followers: 4)
Transportation Research Interdisciplinary Perspectives     Open Access   (Followers: 2)
Transportation Research Part A: Policy and Practice     Hybrid Journal   (Followers: 38)
Transportation Research Part B: Methodological     Hybrid Journal   (Followers: 38)
Transportation Research Part C: Emerging Technologies     Hybrid Journal   (Followers: 29)
Transportation Research Procedia     Open Access   (Followers: 6)
Transportation Research Record : Journal of the Transportation Research Board     Full-text available via subscription   (Followers: 29)
Transportation Safety and Environment     Open Access   (Followers: 1)
Transportation Science     Full-text available via subscription   (Followers: 26)
Transportation Systems and Technology     Open Access  
TRANSPORTES     Open Access   (Followers: 3)
Transportmetrica A : Transport Science     Hybrid Journal   (Followers: 8)
Transportmetrica B : Transport Dynamics     Hybrid Journal   (Followers: 1)
Travel Behaviour and Society     Full-text available via subscription   (Followers: 9)
Travel Medicine and Infectious Disease     Hybrid Journal   (Followers: 2)
Urban, Planning and Transport Research     Open Access   (Followers: 33)
Vehicles     Open Access  
Vehicular Communications     Full-text available via subscription   (Followers: 4)
World Electric Vehicle Journal     Open Access   (Followers: 3)
World Review of Intermodal Transportation Research     Hybrid Journal   (Followers: 5)
Транспортні системи та технології перевезень     Open Access  

           

Similar Journals
Journal Cover
Transportation Research Record : Journal of the Transportation Research Board
Journal Prestige (SJR): 0.589
Citation Impact (citeScore): 1
Number of Followers: 29  
 
  Full-text available via subscription Subscription journal
ISSN (Print) 0361-1981 - ISSN (Online) 2169-4052
Published by Sage Publications Homepage  [1174 journals]
  • Evaluation of Steel Bridge Details for Susceptibility to
           Constraint-induced Fracture

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      Authors: Domenic A. Coletti, Anthony P. Ream, Brandon W. Chavel
      Abstract: Transportation Research Record, Ahead of Print.
      Historically, reports of significant problems associated with details featuring intersecting welds in steel bridges have been rare. However, there have been several notable cases involving constraint-induced fracture (CIF). CIF is a particular concern since it can occur in a brittle fashion, suddenly and without warning (different from other types of problems, such as corrosion or fatigue crack growth, for example). CIF generally occurs in details that feature a high degree of constraint (leading to a high level of stress triaxiality), in combination with high levels of tensile stress (particularly from residual stresses) and the presence of a notch-like or crack-like planar discontinuity approximately perpendicular to the primary flow of tensile stress. Details subject to a high degree of constraint often feature the intersection of two or three welded structural elements. The distinction between “intersecting welds” and “constraint resulting from the intersection of welded structural elements” is important. This paper summarizes the findings and recommendations of a recently completed report reflecting the current state of knowledge about CIF in steel bridges. The report is based on a review of previous research, industry practices, and the input of a panel of steel bridge industry experts. It provides a review of the fundamental principles of CIF and presents a general procedure for evaluating steel bridge details for susceptibility to CIF, including examples of assessments of commonly used steel bridge details.
      Citation: Transportation Research Record
      PubDate: 2022-06-23T12:23:47Z
      DOI: 10.1177/03611981221103228
       
  • Learning-Based Model for Evaluating the Impact of Neighborhood Design on
           Travel Behavior

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      Authors: Abdul Rahman Masoud, Ahmed Osman Idris, Gordon Lovegrove
      Abstract: Transportation Research Record, Ahead of Print.
      This research developed an agent-based model that evaluates the impact of neighborhood design on travel behavior while accounting for habit formation, social interactions, various levels of information provision, and awareness of transport and land use system changes. The developed model employs a framework that integrates random utility maximization theory with reinforcement learning concepts to account for the bounded rationality and knowledge learning process. Moreover, the model utilizes the diffusions of innovations theory to simulate how agents propagate information across family members and co-workers. It also adds a time dimension to the modal shift process, which could be used to indicate the relative duration to reap the full benefits of proposed scenarios. The model was applied to a neighborhood in Kelowna, British Columbia, Canada, to assess the impact on travel behavior of the SMARTer growth principles. The results showed that retrofitting non-motorized networks has more impact on modal shift than retrofitting road networks. This implies that infrastructure investments related to providing more accessibility for non-motorized users may be more socially and sustainably profitable than investments in policies targeting auto users. In addition, the results revealed that land use policies led to higher modal shift to non-motorized modes compared to retrofitting the transportation network, which highlights the importance of integrating land use and transportation planning. Similarly, the results demonstrated that transportation demand management policies can provide a positive stimulus to commuters to maintain familiarity with active transportation (AT) modes, which led in the presented case study to an increase in AT modal share.
      Citation: Transportation Research Record
      PubDate: 2022-06-23T12:21:47Z
      DOI: 10.1177/03611981221102154
       
  • Developing a Disaster Chain Method to Evaluate Transportation Systems: A
           Pilot Study of Predicting Debris Blockages in Disaster-Response Road
           Systems

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      Authors: Siao-Syun Ke, Chih-Hao Hsu
      Abstract: Transportation Research Record, Ahead of Print.
      Suitable transportation systems are vital for the functioning of urban areas. Such systems connect all major locations, including residential and commercial locations, in these areas. The effectiveness of the response of an urban area to an earthquake depends on the road system in the area. A feasible and efficient approach to evaluating the capacity of road systems to allow safe and efficient emergency transportation for affected residents in the aftermath of an earthquake should be developed. Ground transportation systems are vulnerable to earthquakes. For example, ground motion in the 1994 Northridge, 1995 Kobe, 1999 Chi-Chi, and 2018 Hokkaido earthquakes caused severe damage to urban roads and bridges. Moreover, for areas with a high building density that are prone to high-intensity earthquakes, it is important to be able to estimate the risk of road blockage caused by collapsed buildings. In the present study, a disaster impact chain was established to evaluate the probability and effects of buildings collapsing in an earthquake. This chain was used as the basis for a road blockage model and for the formulation of suitable procedures and methods for earthquake response. The results of this study indicate that buildings in strong-motion zones are severely damaged by high-intensity earthquakes. Falling debris from these buildings can lead to the blockage of rescue roads, delaying the transport of injured individuals to hospital after an earthquake. The results of this study can aid authorities in making decisions related to transportation system management during earthquake disasters.
      Citation: Transportation Research Record
      PubDate: 2022-06-23T12:20:08Z
      DOI: 10.1177/03611981221102152
       
  • Minimizing the Effects of Urban Mobility-on-Demand Pick-Up and Drop-Off
           Stops: A Microscopic Simulation Approach

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      Authors: Philipp N. Stueger, Fabian Fehn, Klaus Bogenberger
      Abstract: Transportation Research Record, Ahead of Print.
      Short-term disruptions can have a long-lasting negative effect on traffic flow exceeding the duration of the disruption itself. This is especially the case when traffic demand approaches the network’s capacity. On-demand ride-sourcing services like ride-hailing and ride-pooling do not only have an impact on the overall kilometers driven in a network, but also conduct frequent stopping maneuvers to let passengers board and alight. As further growth of such services is expected, municipalities will need to find ways to organize and, if needed, regulate such activities. This paper proposes, evaluates, and discusses two possible methods that can be part of a holistic strategy to mitigate the impacts of frequent mobility-on-demand curbside stops in an urban environment. The first method adapts the positions of stops at an intersection according to real-time signal timings without adding another variable to the already quite complex traffic signal optimization. The second method discusses a temporary reduction of the number of allowed stopping maneuvers on saturated street sections or in other sensitive areas. Both methods are evaluated using microscopic traffic simulation and result in significant reductions of average vehicle delay as well as standard deviation thereof in all investigated traffic demand scenarios. These results indicate that the proposed methods can help to preserve a stable traffic state in situations close to the capacity limit, which is to the benefit of all stakeholders involved.
      Citation: Transportation Research Record
      PubDate: 2022-06-23T12:18:37Z
      DOI: 10.1177/03611981221101894
       
  • Evaluating Cost Savings from Truck Caravanning

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      Authors: Vasileios Liatsos, Dimitrios Giampouranis, Mihalis Golias, Sabyasachee Mishra, John Hourdos, Razi Nalim, Mark T. Frohlich, Clayton Nicholas
      Abstract: Transportation Research Record, Ahead of Print.
      Truck platooning and related autonomous vehicle coordination concepts have been proposed as sustainable ways to increase profits and improve service quality. Recently the concept of truck caravanning, a hybrid truck platooning with only one truck driver required per platoon, has been proposed in the literature. This paper describes the research effort in developing a model that can estimate the cost savings of truck caravanning. The motivation of the proposed model is to investigate if substantial monetary savings exist to justify the initial capital investment (both in equipment and infrastructure) required for the implementation of the truck caravanning concept. A linear programming model is developed and used to evaluate different size networks. Results from numerical experiments indicate that a caravan size of four trucks or greater is needed for significant cost savings to be achieved and that driver compensation is the most critical factor dictating profitability.
      Citation: Transportation Research Record
      PubDate: 2022-06-23T12:16:27Z
      DOI: 10.1177/03611981221101890
       
  • Aircraft Insurance Costs Management for Sustainable General Aviation:
           Insights From General Aviation Enterprises in China

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      Authors: Qian Ma, Guojun Wang
      Abstract: Transportation Research Record, Ahead of Print.
      Little research has examined how to effectively reduce general aviation aircraft (GAA) insurance costs (premiums), even though it has grown to be a heavy financial burden adversely affecting the sustainable development of general aviation (GA). In contrast to previous research that dealt solely with airline insurance, this research studies the insurance cost management issue of GAA from the perspective of supply and demand. Specifically, this paper focuses on analyzing significant factors influencing GAA insurance premiums and the degree of incidence with the risk system. This empirical research is based on a unique dataset of GA enterprises in China during 2017 to 2019 and utilizes the second synthetic of gray incidence analysis (SSDGIA) model and entropy weight analysis. First, it is found that the fleet profile, loss record, and individual GA operational performance are the critical elements related to premiums. Additionally, there is an increasing dependence of premiums on direct loss performance. Second, the degree of incidence between premiums and the risk system (
      Citation: Transportation Research Record
      PubDate: 2022-06-23T12:15:08Z
      DOI: 10.1177/03611981221101616
       
  • Combined Hub Location and Service Network Design Problem: A Case Study for
           an Intermodal Rail Operator and Structural Analysis

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      Authors: Ralf Elbert, Johannes Rentschler, Jessica Schwarz
      Abstract: Transportation Research Record, Ahead of Print.
      In intermodal transportation, hubs are facilities that perform switching, sorting, connecting, and consolidating functions between many origins and destinations. Hub location problems (HLP) accordingly involve the location of hubs but include abstract network design decisions as well. In the past, the strategic location decision and the more tactical network design decision, in the form of a service network design problem (SNDP), have been considered separately. However, the SNDP is based on an existing hub network and the HLP could benefit from a more detailed network design. For this reason, this paper presents the combined hub location and service network design problem (C-HL-SNDP), which considers the strategic and tactical planning dimensions in an integrated manner. In a case study of a German intermodal operator, the paper shows that integrated modeling can be used to produce very good and realistic solutions that generate added value. The combined model with a classical HLP approach is compared and a structural analysis of the solution properties is performed. With this, it can be shown that the different consideration of economies of scale and economies of density lead to fundamentally different solutions.
      Citation: Transportation Research Record
      PubDate: 2022-06-23T12:13:47Z
      DOI: 10.1177/03611981221101391
       
  • Resilience Analysis of New York City Transportation Network After Snow
           Storms

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      Authors: Reza Mirjalili, Hojjat Barati, Anil Yazici
      Abstract: Transportation Research Record, Ahead of Print.
      This study presents a quantitative analysis of the snow storm resilience of New York City (NYC) by utilizing network science-based system performance functions and publicly available datasets, that is, New York Department of Sanitation’s snow removal operation and NYC traffic speed data. Several graph theory based metrics and some heuristic metrics are utilized to calculate the temporal changes in transportation network functionality along eight snow events. The NYC transportation network is updated based on snowplow movements, and the performance indexes (PIs) for all metrics are calculated throughout the snow storm timeline. Since PI graphs rely on network topology but not the actual traffic conditions, the times that the system bounces back to “regular” conditions (i.e., time-to-recovery/resilience) are calculated based on the similarity between hourly speed distributions on NYC roads. Bhattacharyya distance and Kolmogorov–Smirnov test are used as measures for distribution similarity. Accordingly, the PI values that correspond to the recovery times are also identified. Within the limitations of the size of the snow storm sample, the findings show that less data-intensive graph theory metrics can be used to estimate the transportation network performance—an estimation that would require extensive and detailed data otherwise. Accordingly, these metrics can be used to make resilience predictions for future events through simulations on modified network topology, and help make recovery forecasts to inform local governments and businesses on when to resume regular operations.
      Citation: Transportation Research Record
      PubDate: 2022-06-23T12:13:08Z
      DOI: 10.1177/03611981221101034
       
  • Toward Formalization and Monitoring of Microscopic Traffic Parameters
           Using Temporal Logic

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      Authors: Mariam Nour, Mohamed H. Zaki
      Abstract: Transportation Research Record, Ahead of Print.
      Smart mobility is transforming the way the current transportation network is envisioned. It holds the promise of a more sustainable, safer, and efficient future for commuters. Nevertheless, traffic management centers are constantly facing the challenges of ensuring that transportation system components are operating as expected and in a safe manner. As a result, research efforts on improving traffic monitoring aim to design and implement novel approaches for safety applications. In this paper, we adopt formal methods to specify and apply reason to the traffic network’s complex properties. Formal methods provide a framework to rigorously define the safe operation of the traffic network by capturing non-conforming travel behavior, exploring various possible states of vehicular traffic, and detecting any irregularities that may arise. In this work, a new approach to traffic monitoring is proposed, which uses specification-based monitoring. We develop monitors that define traffic parameters, such as conforming to speed limits and maintaining appropriate headway. A formal language known as Signal Temporal Logic is used to specify and analyze these traffic rules. The proposed framework is then applied to a calibrated micro-simulated highway network to identify whether individual vehicle trajectories violate or satisfy the proposed specifications. Statistical analysis of the outputs shows that our proposed approach is effective in differentiating between violating and conforming vehicles. This approach can be used by traffic management centers that are seeking to accommodate emerging mobility technologies that are autonomous and connected. In particular, the presented work can be valuable in studying traffic stream properties, identifying possible hazards, and providing valuable feedback for automating traffic monitoring systems.
      Citation: Transportation Research Record
      PubDate: 2022-06-23T12:12:38Z
      DOI: 10.1177/03611981221100535
       
  • Effects of Oil/Asphalt Emulsion Formulation on Particle Size and Stability

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      Authors: Conglin Chen, Lanqin Lin, Tao Ma
      Abstract: Transportation Research Record, Ahead of Print.
      This investigation evaluated the factors of penetrant types, asphalt contents, and emulsifier contents on the particle sizes of emulsified penetrants, emulsified asphalt, and oil/asphalt emulsions in the emulsion formulation. The particle sizes of emulsions were obtained by laser particle size analyzer tests. The residues of emulsions obtained after the high-temperature evaporative technique were assessed through conventional binder tests such as softening point, penetration, and ductility tests. The storage stability of oil/asphalt emulsions was evaluated as well. Additionally, the molecular dynamics simulation was employed to study the interfacial interaction between materials in the emulsion system at the atomic scale. The results showed the great potential of using the commercial penetrants adopted for this study as alternatives to kerosene in emulsions with smaller particle sizes and better stability. The emulsifier content had significant effects on particle size and stability of emulsions. A higher emulsifier content had positive effects on decreasing the particle sizes and improving the stability of emulsions; however, it negatively affected the ductility of the emulsion residues. The particle sizes were noticed to be highly correlated to stability, emulsifier content, and interfacial formation energy of the emulsions.
      Citation: Transportation Research Record
      PubDate: 2022-06-23T12:12:03Z
      DOI: 10.1177/03611981221100512
       
  • Accelerated Pavement Testing Validation of a Pavement Response Model Using
           Three-Dimensional Finite Element Analysis Software: Two Case Studies

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      Authors: Fawaz Kaseer, James Greene, Bouzid Choubane
      Abstract: Transportation Research Record, Ahead of Print.
      Accelerated pavement testing (APT) provides valuable information concerning the short- and long-term performance and life expectancy of pavement structures in a very short period as compared to full-scale field tests. Pavement modeling can produce early, reliable, and beneficial guidance that can be used to design and implement future APT experiments or extend the experimental results to similar materials and structures. Combining actual APT experimental data with well-calibrated models can provide complete and thorough investigations while saving agencies time and resources. The main objective of this study is to evaluate the effectiveness and accuracy of the 3D-Move Analysis Software (three-dimensional finite element software [3D FE]) in calculating pavement responses through a comparison with measured pavement responses and distresses from previous APT experiments using the Florida Department of Transportation heavy vehicle simulator (HVS). 3D-Move uses a continuum-based finite-layer approach to calculate pavement responses under various loading conditions. Results indicated that pavement responses, specifically longitudinal horizontal (tensile) strains at the bottom of the asphalt layer and transverse horizontal (tensile) strains at the surface of the asphalt layer, calculated by 3D FE are relatively similar to those measured in APT experiments. The calculated impact of the asphalt mixture properties, loading level, loading temperature, and the distance (offset) from the tire edge on pavement responses was consistent with those measured in HVS testing. Therefore, 3D FE analysis can be effectively used to compare the relative cracking performance of asphalt mixtures and aid in designing practical APT experiments and extending the results to similar asphalt mixtures and pavement structures.
      Citation: Transportation Research Record
      PubDate: 2022-06-23T12:11:34Z
      DOI: 10.1177/03611981221099911
       
  • Pavement Maintenance Program at the Network Level: Mixed-Integer
           Programming with Multiple Objectives

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      Authors: Md Al Amin
      Abstract: Transportation Research Record, Ahead of Print.
      Pavement network conditions deteriorate over the years of use. To keep pavement conditions at acceptable levels, highway agencies plan pavement maintenance and rehabilitation (M&R) programs and perform accordingly. Highway agencies usually face budget variability for pavement M&R activities because of limited resources, economic conditions, and changes in policies. The situation makes it difficult for highway agencies to keep an acceptable pavement condition at the network level. Therefore, it is important for highway agencies to adopt M&R policies that can maximize the network condition as well as handle the deviation of the network condition considering the available maintenance funds. In this paper, a multi-period multi-objective linear integer programming model is proposed. Two objectives, maximization of the average network condition and minimization of deviation of the network condition from an idealized network condition trend, are considered in the formulation. The model is formulated for fixed M&R budgets, as well as for variable M&R budgets. The proposed model provides an M&R program for the pavement network that helps decision makers to manage pavement maintenance programs considering budgetary constraints. A case study examining a network of 45 pavement sections is conducted. The solutions of the fixed-budget and variable-budget model are presented. In addition, the values of the system to the decision maker are discussed. Results show that the proposed model is an attractive way to manage pavement maintenance programs at the network level.
      Citation: Transportation Research Record
      PubDate: 2022-06-23T11:57:58Z
      DOI: 10.1177/03611981221099910
       
  • Multiperspective Analysis of Pandemic Impacts on U.S. Import Trade: What
           Happened, and Why'

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      Authors: Daniel Smith, Paul Bingham, Daniel Hackett, Jeffrey Smith
      Abstract: Transportation Research Record, Ahead of Print.
      U.S. container ports have experienced unpresented congestion since mid-2020. The congestion is generally attributed to import surges triggered by heavy spending on consumer goods during the COVID-19 pandemic. Port congestion has been compounded by the inability of importers to retrieve, receive, and process all the inbound goods they have ordered, resulting in supply chain shortfalls and economic disruption. How can the shipping industry and government organizations predict the end of the current surge and anticipate future surges' Expected seasonal variations in import volume are associated with peak holiday shopping periods; nonseasonal import surges are signaled by other factors. The research goes beyond transportation data sources to examine broader connections between import volume and indicators of economic and retail industry conditions. The strongest and most useful relationship appears to be between retail inventory indicators and containerized import growth. From January 2018 through July 2021, there was a relatively strong negative correlation between retail inventory- and import TEU indices with a 4-month lag (corresponding roughly to the time between import orders and -arrival). In the 2020 to 2021 pandemic period the negative correlation was stronger, again with a 4-month lag. These findings suggest that observers might anticipate import surges after marked, nonseasonal drops in retail inventories, and that import surges are likely to last until target inventory levels are restored. In a broader sense, an awareness of the linkages between consumer demand, retail chain responses, and containerized import volumes could better inform port, freight transportation, and government planning and policy choices.
      Citation: Transportation Research Record
      PubDate: 2022-06-23T11:55:12Z
      DOI: 10.1177/03611981221098663
       
  • Autonomous Minibus Service With Semi-on-Demand Routes in Grid Networks

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      Authors: Max T. M. Ng, Hani S. Mahmassani
      Abstract: Transportation Research Record, Ahead of Print.
      This paper investigates the potential of autonomous minibuses which take on-demand directional routes for pick-up and drop-off in a grid network of wider area with low density, followed by fixed routes in areas with greater demand. Mathematical formulation for generalized costs demonstrates its benefits, with indicators proposed to select existing bus routes for conversion with the options of zonal express and parallel routes. Simulations on modeled scenarios and case studies with bus routes in Chicago show reductions in both passenger costs and generalized costs compared with existing fixed-route bus services between suburban areas and the central business district.
      Citation: Transportation Research Record
      PubDate: 2022-06-23T11:53:52Z
      DOI: 10.1177/03611981221098660
       
  • High-Resolution Fuel Consumption Model for Better Characterizations of
           High-Speed Scenarios

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      Authors: Jianchang Huang, Guohua Song, Zeyu Zhang, Yun Jiang
      Abstract: Transportation Research Record, Ahead of Print.
      A detailed and accurate fuel model fuel consumption model that reflects real-world fuel consumption is required as input for devising and executing a model policy for prospective regulatory tools. The fuel consumption model based on the vehicle-specific power (VSP) has rapidly become the primary development direction since the release of the Motor Vehicle Emissions Simulator (MOVES) model. However, fuel consumption cannot be accurately characterized under high-speed scenarios. This work develops two fuel consumption models for the light-duty (gasoline) vehicles that can better characterize fuel consumption for light-duty vehicles under high-speed scenarios. For model 1, the VSP of −5kW/ton is a crucial turning point. When VSP∈ [−30, −5] kW/ton, the fuel rate is only determined by speed. When VSP∈(−5, 30], the fuel rate will gradually increase with VSP, and the growth characteristics will vary with speed. Model 2 develops the new interpretations for VSP and forms the one-to-one correspondence between the fuel rate and the new VSP. The two models can separately improve the accuracy by 12.2% and 13.8% compared with the conventional model. The fuel factor differences become significant when speed is higher than 65 km/h, which are separately 30.66% and 28.13% higher than the conventional VSP model when the speed is 100 km/h. Further, the fuel factors of the two models for freeways are, respectively, 6.33% and 7.56% higher than the conventional VSP model, and the distinction for arterial, collector, and local street roads is not notable.
      Citation: Transportation Research Record
      PubDate: 2022-06-23T11:50:51Z
      DOI: 10.1177/03611981221098401
       
  • Factors Affecting Demand Consolidation in Urban Air Taxi Operation

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      Authors: Haleh Ale-Ahmad, Hani S. Mahmassani
      Abstract: Transportation Research Record, Ahead of Print.
      Urban air taxi (UAT) is envisioned as a point-to-point, (nearly) on-demand, and per-seat operation of passenger-carrying urban air mobility (UAM) in its mature state. A high flight load factor has been identified as one of the influential components in the successful operation of UAT. However, the uncertainties in demand, aircraft technology, and concept of operations have raised doubts about the viability of UAT. This study examines the impacts of exogenous parameters, such as demand intensity, demand spread, and ground speed, in addition to design parameters, including aerial speed, maximum acceptable delay, and reservations on average load factor and rate of rejected requests. The dynamic and stochastic problem of UAT fleet operation is studied by implementing a dynamic framework that aims to provide a solution to the problem via a discrete-event simulation. The results highlight the significance of demand spread, ground speed, and maximum acceptable delay in demand consolidation. Therefore, to ensure a high aircraft load factor, the UAT operator should specify the maximum acceptable delay and reservation time window given the demand pattern and ground-based transportation in the network.
      Citation: Transportation Research Record
      PubDate: 2022-06-23T11:48:41Z
      DOI: 10.1177/03611981221098396
       
  • Estimating Freeway Lane-Level Traffic State with Intelligent Connected
           Vehicles

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      Authors: Xiaobo Liu, Ziming Zhang, Tomio Miwa, Peng Cao
      Abstract: Transportation Research Record, Ahead of Print.
      This paper proposes a methodology for estimating lane-level traffic state for freeways by fusing data from intelligent connected vehicles (ICVs) with fixed detector data (FDD) and probe vehicle data (PVD). With microscopic vehicle trajectories of ICVs and their surrounding vehicles, the proposed methodology integrates a multilane traffic flow model into the data assimilation framework based on extended Kalman filter (EKF), in which traffic measurement models are formulated for ICV data, PVD, and FDD, respectively, to fit their different characteristics. Simulation experiments are conducted to test the performance of the proposed methodology with various penetration rates of ICVs, using a set of simulated ICV data based on the Next Generation SIMulation (NGSIM) data sets. The results demonstrate that by utilizing only 3% to 5% ICVs in the mixed traffic, the proposed methodology could produce an accurate estimate of lane-level traffic speed and a reasonable estimate of lane-level traffic density.
      Citation: Transportation Research Record
      PubDate: 2022-06-23T11:47:14Z
      DOI: 10.1177/03611981221098395
       
  • Topological Approach for Optimizing Railroad Freight Network Restoration
           after Disruptions

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      Authors: Fei Wu, Paul M. Schonfeld, Bilal Ayyub, Myungseob Kim
      Abstract: Transportation Research Record, Ahead of Print.
      A topology-based method is proposed for optimizing the restoration sequence of damaged components in a disrupted rail freight network. Formulated as a demand-weighted average of reciprocal shortest path lengths, network efficiency is used as an indicator of overall connectivity for origin–destination (OD) pairs having freight demand. With the fixed demand matrix, a given network configuration, and a given disruption scenario, the cumulative loss of network efficiency during the restoration process is computed for each evaluated restoration sequence, using network efficiency values in intermediate network states as well as the duration of each restoration phase (i.e., restoration plus access time). This cumulative loss is treated as a measure of post-disruption network resilience, and is minimized with a simple genetic algorithm (GA) that finds the corresponding optimized restoration sequence, which also determines the optimized restoration schedule. The proposed method is demonstrated in a synthesized numerical case of a small network and a disruption scenario. The GA can find the globally optimal restoration sequence relatively fast, with its effectiveness further verified through exhaustive enumeration for three additional disruption scenarios. Sensitivity analysis results indicate that higher topological centrality and freight throughput of damaged nodes or disruption-induced isolation of some nodes are responsible for higher minimized loss of cumulative efficiency. The optimized restoration sequence tends to prioritize nodes and adjacent links with relatively high freight throughput in normal operation.
      Citation: Transportation Research Record
      PubDate: 2022-06-23T11:46:04Z
      DOI: 10.1177/03611981221097397
       
  • Effects of Distance and Reliability on Value of Time in Intercity Freight
           Transportation: An Adaptive Experiment in China

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      Authors: Hao Liu, Rong Zhang, Wenliang Jian, Suxiang Zhang
      Abstract: Transportation Research Record, Ahead of Print.
      Road–rail container intermodal transportation is considered a solution to reduce the share of truck transportation in China. A modal shift from truck to intermodal alternatives requires a better understanding of freight mode choice behavior and improved estimations of the value of service attributes. This paper focuses on the effects of distance and reliability on the value of time (VOT). An adaptive experiment is conducted on potential customers of intermodal transportation in the Yangtze River Delta area, China. Multinomial logit (binary logit) and mixed logit models are estimated for eight specifications. The results show that shipper characteristics, commodity characteristics, and shipment characteristics significantly influence the mode choice behavior. Specifications with an interaction term between the logarithm of distance and transportation time perform better. The VOT of short-distance transportation is higher than that of long-distance transportation. The rate of VOT reduction decreases with increasing distance. In addition, incorporating the reliability variable in model specifications leads to a more homogeneous random parameter distribution of time and a lower VOT. This study helps intermodal operators to optimize product and design pricing strategies. Moreover, the proposed measures help to promote the modal shift from truck to road–rail container intermodal transportation.
      Citation: Transportation Research Record
      PubDate: 2022-06-23T11:44:23Z
      DOI: 10.1177/03611981221097096
       
  • Performance Evaluation and Characterization of Extracted Recycled Asphalt
           Binder With Rejuvenators

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      Authors: Mahmoud Samara, Daniel Offenbacker, Yusuf Mehta, Ayman Ali, Mohamed Elshaer, Christopher Decarlo
      Abstract: Transportation Research Record, Ahead of Print.
      Rejuvenators are used in the asphalt industry to improve the performance and durability of aged binders and facilitate the use of recycled asphalt materials. The purpose of this study was to evaluate the impact of rejuvenator type and dose on the laboratory performance of asphalt binders. For this study, recycled asphalt pavement (RAP) and extracted RAP binder were obtained from an airfield reconstruction project located in Atlantic City, NJ. One petroleum-based (aromatic extract) and three organic-based (corn oil, tall oil, and modified vegetable oil) rejuvenators were evaluated in this study. Each rejuvenator was used at two different rejuvenator doses (6% and 12% by total RAP binder weight) and was aged at three different levels. Performance grade testing, frequency sweep tests, critical temperature differential (ΔTc ), and Fourier transform infrared spectroscopy (FTIR) tests were conducted. Results showed that the use of rejuvenators lowered the high and low performance grade of extracted RAP binders, in particular organic-based rejuvenators had a greater impact on the performance grade. ΔT c was also improved through the use of rejuvenators. In fact, the extracted RAP binder exceeded the high severity ΔTc threshold (−5°C), whereas the rejuvenated RAP binders improved ΔT c to values greater than the low severity threshold (−2.5°C). Similar findings were observed from the Glover-Rowe parameter as well, in which rejuvenated RAP binders improved the cracking resistance of the extracted RAP binder. When assessing the aging susceptibility, modified vegetable oil and corn oil rejuvenators showed the smallest change in performance between aging levels.
      Citation: Transportation Research Record
      PubDate: 2022-06-23T11:43:44Z
      DOI: 10.1177/03611981221097091
       
  • Metro Speed Profile Optimization Considering Passenger Comfort: Model and
           Application

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      Authors: Dimitrios Roumpekas, Christina Iliopoulou, Konstantinos Kepaptsoglou
      Abstract: Transportation Research Record, Ahead of Print.
      Efficient timetable and speed profile determination are critical in improving the energy performance of railway systems. Relevant speed profile optimization models for railway systems typically aim at the minimization of energy consumption and passenger waiting times. Still, passenger comfort during the accelerations and decelerations of the train is significant for service quality, yet so far has been largely overlooked in relevant models. In this context, this study proposes a speed profile optimization model considering the effect of acceleration on passengers. Three distinct speed profiles are developed based on real-world data and used as input for the model. Subsequently, an integer linear programming model is formulated, minimizing the running time and energy consumption, and maximizing passenger comfort. The proposed model is applied to Athens (Greece) metro line 3 (blue line). Results corroborate the effectiveness of the proposed model in reducing travel times, while taking into account passenger comfort.
      Citation: Transportation Research Record
      PubDate: 2022-06-23T11:41:04Z
      DOI: 10.1177/03611981221096443
       
  • Weather-Based Lane-Change Microsimulation Parameters for Safety and
           Operational Performance Evaluation of Weaving and Basic Freeway Segments

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      Authors: Anik Das, Mohamed M. Ahmed
      Abstract: Transportation Research Record, Ahead of Print.
      It is well recognized that adverse weather conditions have significant negative impacts on safety and mobility of transportation systems. Microsimulation modeling has emerged as a cost-effective tool to quantify the safety and operational effects arising from adverse weather. Developing a realistic microsimulation model necessitates adjusting driving behavior models through trajectory-level data. This study contributes a methodology to update lane-change parameters to develop weather-specific microsimulation models based on different freeway facilities, and ultimately evaluate the safety and operational performance of the roadways. Representative parameters in various weather and facility types were extracted using an automated process. As part of the comprehensive assessment of the adjusted parameters, a weaving section and a basic freeway segment on Interstate 80 in Wyoming were identified as potential candidates. The safety and operational analyses were conducted using VISSIM. Various simulation scenarios were designed based on the field traffic flow data. The safety analysis using three surrogate measures of safety including time-to-collision, deceleration rate to avoid collision, and post encroachment time revealed that adverse weather generated a higher number of conflicts than did clear weather for both facilities. The operational analysis suggested that adverse weather produced lower average speed and higher total travel time and delay than clear weather. The demonstrated methodology could be used in assessing various connected vehicle applications associated with lane change in microsimulation from safety and operational perspectives and could be adopted by transportation agencies to develop weather-based microsimulation models.
      Citation: Transportation Research Record
      PubDate: 2022-06-23T11:39:44Z
      DOI: 10.1177/03611981221096111
       
  • Estimating Potential Employment Impact of the Charging Infrastructure used
           to Support Transportation Electrification in the United States

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      Authors: Yue Ke, Marianne Mintz, Yan Zhou
      Abstract: Transportation Research Record, Ahead of Print.
      Increased concern over greenhouse gas (GHG) emissions and climate change is encouraging many states, companies, and consumers to focus on zero emission vehicle technologies such as electric vehicles (EVs). A major barrier to widespread EV adoption, however, is range anxiety as there is currently insufficient electric vehicle supply equipment (EVSE) available. Although not the primary goal primary of EVSE installations, one of their side effects and a goal of President Biden’s infrastructure plans is their impact on employment, both initially as stations are developed and activated and over time and as they continue to provide charging to a growing population of EVs. This study estimates the potential employment effects of the deployment and operation of President Biden’s goal of installing 500,000 charger plugs. To do this, we develop an input-output (IO) based model called JOBS EV. Unlike existing analyses, JOBS EV includes both the employment effects caused by the front-of-meter EVSE equipment needed at a particular site and the back-of-meter or upstream equipment used to obtain power from the existing utility’s distribution network. The model results indicate that approximately 1.1 million new jobs will be created over a 10-year period. The modeling process outlined in this paper, in addition to the results presented, may be useful to stakeholders involved in transportation decarbonization efforts as another means of evaluating the costs and benefits of pursuing electrification. Further work is needed to improve the underlying IO model to better account for nascent industries, to accurately calculate local share percentages, and to capture the employment effects of the complete EVSE life cycle.
      Citation: Transportation Research Record
      PubDate: 2022-06-23T11:38:04Z
      DOI: 10.1177/03611981221095750
       
  • Application of Emerging Data Sources for Pedestrian Safety Analysis in
           Charlotte, NC

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      Authors: Ian Hamilton, Kristin Kersavage, R.J. Porter, Vikash Gayah, Josie Sanchez, Keith Smith, Carol Tan, Ana Maria Eigen
      Abstract: Transportation Research Record, Ahead of Print.
      Pedestrian safety is a growing concern for transportation planners and safety engineers at both local and state levels. Continued advancements in data availability, data integration abilities, and analysis methodologies offer new opportunities to identify factors influencing pedestrian safety and to quantify their effects to inform data-driven road safety management. The main objective of this study was to spatially integrate Highway Safety Information System data with multijurisdictional and emerging datasets to analyze two measures of pedestrian safety performance in Charlotte, NC: (1) the severity of a pedestrian crash that has occurred, and (2) the probability that a pedestrian crash will occur on a given roadway segment. To accomplish the objectives, the study explored several high-priority research topics in safety data and analysis, including pedestrian exposure analysis and probe data integration. The research team developed a pedestrian count model to predict pedestrian volumes at locations without pedestrian counts and integrated speed information from probe data to supplement other roadway and contextual transportation data available from several agencies. Pedestrian exposure at a given intersection was found to be significantly influenced by demographic and socioeconomic characteristics, employment, land use, sidewalk presence, transit access, and roadway and intersection characteristics. The project team identified numerous significant factors that influenced pedestrian crash severity and probability, including outputs from the pedestrian exposure model, observed vehicle speeds, traffic volumes, intersection proximity, and other crash-related factors. The results could be used to identify locations that are more susceptible to pedestrian safety issues.
      Citation: Transportation Research Record
      PubDate: 2022-06-23T11:36:10Z
      DOI: 10.1177/03611981221093330
       
  • Decentralised Multi-Agent Reinforcement Learning Approach for the Same-Day
           Delivery Problem

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      Authors: Elvin Ngu, Leandro Parada, Jose Javier Escribano Macias, Panagiotis Angeloudis
      Abstract: Transportation Research Record, Ahead of Print.
      Same-day delivery (SDD) services have become increasingly popular in recent years. These have been usually modeled by previous studies as a certain class of dynamic vehicle routing problem (DVRP) where goods must be delivered from a depot to a set of customers in the same day that the orders were placed. Adaptive exact solution methods for DVRPs can become intractable even for small problem instances. In this paper, the same-day delivery problem (SDDP) is formulated as a Markov decision process (MDP) and it is solved using a parameter-sharing Deep Q-Network, which corresponds to a decentralised multi-agent reinforcement learning (MARL) approach. For this, a multi-agent grid-based SDD environment is created, consisting of multiple vehicles, a central depot, and dynamic order generation. In addition, zone-specific order generation and reward probabilities are introduced. The performance of the proposed MARL approach is compared against a mixed-integer programming (MIP) solution. Results show that the proposed MARL framework performs on par with MIP-based policy when the number of orders is relatively low. For problem instances with higher order arrival rates, computational results show that the MARL approach underperforms MIP by up to 30%. The performance gap between both methods becomes smaller when zone-specific parameters are employed. The gap is reduced from 30% to 3% for a 5 × 5 grid scenario with 30 orders. Execution time results indicate that the MARL approach is, on average, 65 times faster than the MIP-based policy, and therefore may be more advantageous for real-time control, at least for small-sized instances.
      Citation: Transportation Research Record
      PubDate: 2022-06-23T11:35:13Z
      DOI: 10.1177/03611981221093324
       
  • Solving the Curb Space Puzzle Through the Development of a Curb Space
           Allocation Tool

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      Authors: Alek L. Pochowski, Stephen Crim, Like Liu, Lake Trask, Christine Sherman Baker, Sarah Woodworth, Jessica Klion
      Abstract: Transportation Research Record, Ahead of Print.
      With new modes and technologies including ride-hail apps, e-commerce deliveries, and the revolution in micromobility services changing the transportation landscape at the curbside, jurisdictions like Arlington County, Virginia, have sought to develop tools to reconsider the allocation of curb space to provide the greatest economic and societal benefit to users of the transportation system. While other jurisdictions and researchers have developed a theoretical approach to allocating curb space under the premise that on-street parking is unlikely to provide the greatest economic or societal benefit, Arlington County sought to create a tool that allocates curb space with demand constraints and data relevant to the context of Arlington County. The developed curb space allocation tool uses six modules: (i) ride-hailing services, (ii) commercial loading, (iii) on-street parking, (iv) transit service, (v) micromobility, and (vi) non-transportation uses (parklets/streateries), which are all capable of being updated as new data or models become available. The tool uses each module to estimate the demand for each mode and then allocates the curb space to maximize the economic or societal value (number of people served). As a result of this work, Arlington County has developed the foundation for a tool that provides a mechanism for determining the optimal allocation of curb space given a block’s existing or proposed land uses and transportation services and has identified gaps in research and available data to enhance the tool’s usability.
      Citation: Transportation Research Record
      PubDate: 2022-06-23T11:34:51Z
      DOI: 10.1177/03611981221090514
       
  • Multi-Objective Simulation Optimization Integrated With Analytic Hierarchy
           Process and Technique for Order Preference by Similarity to Ideal Solution
           for Pollution Routing Problem

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      Authors: Aslı Boru İpek
      Abstract: Transportation Research Record, Ahead of Print.
      Routing is one of the most important components of logistics and has a vital role in economic growth. Inefficient routing has also contributed to troubling pollutants that have adverse environmental effects worldwide. Over the years, operations research practitioners have therefore drawn considerable attention to the routing problem. In this paper, a pollution routing problem (PRP) with time window constraints and capacitated vehicles is considered to integrate environmental issues in routing for pollution reduction. This work introduces a simulation optimization methodology that includes the realization of important parameters in real-world applications to minimize the total lateness cost and fuel consumption. The proposed method was developed with Simio simulation software and non-dominated sorting genetic algorithm-II (NSGA-II). It evaluates the dynamic system operations over time and performs a comprehensive analysis. In addition, a two-step hierarchical multi-criteria decision-making (MCDM) method is employed to choose the best strategy for PRP. Results of the two-step hierarchical MCDM method demonstrated that the strategy considering the total cost of supply chain is the best alternative for the proposed system. The use of MCDM methods after simulation can be a more robust and effective way to find solutions to such complex problems.
      Citation: Transportation Research Record
      PubDate: 2022-06-23T01:18:26Z
      DOI: 10.1177/03611981221105503
       
  • Trends, Enablers, and Barriers for Car Ownership

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      Authors: Marcio Henrique Fronteli, Edson Pacheco Paladini
      Abstract: Transportation Research Record, Ahead of Print.
      Car ownership has been the object of interest in various research areas. Studies on the topic focus especially on the influence of factors such as environment, life, family events, use, and availability, usually restricted to a given city or region. This paper focuses on recent studies that identified enablers, barriers, and trends related to car ownership in the automotive sector. We use an exploratory-qualitative approach based on systematic mapping of the literature to select papers published between 2019 and March 2021 on the Scopus database. As a result, we first classified the factors that act as enablers or barriers to the acquisition and maintenance of cars. These factors were divided into the following six groups: personal, cultural, political, economic, technological, and environmental. Next, we identified car-ownership-related trends for the automotive sector: purchase replaced by effective use; restrictions on car ownership; autonomous driving; sustainable mobility; new mobility models; customized customer service; real-time integrated modal communication, systematic global traffic, and integrated urban planning. We consider our findings to be relevant contributions to the industry in relation to establishing strategies and public administrators acting in the transportation planning field.
      Citation: Transportation Research Record
      PubDate: 2022-06-23T01:17:14Z
      DOI: 10.1177/03611981221103863
       
  • How Guidance Signage Design Influences Passengers’ Wayfinding
           

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      Authors: Xiaojian Hu, Lurong Xu
      Abstract: Transportation Research Record, Ahead of Print.
      Well-designed guidance signage plays a significant role in the metro environment, ensuring that passengers can reach their destination quickly without anxiety and stress. At present, most metro stations in China use vertical guidance signage (hanging on the walls), which can easily cause misunderstandings in conveying information. Horizontal guidance signage (horizontally attached to the ground) with visual continuity has not yet been used. To explore the influence of different signage designs (vertical, horizontal, and mixed) on passengers’ wayfinding performance, this research utilized virtual reality (VR) technology to develop a VR environment based on a metro station in Nanjing, China. Thirty-six volunteers were randomly divided into six groups based on two variables (guidance signage design and density of passengers), and participated in the wayfinding experiment. During the experiment, three types of wayfinding performance measurements were collected and analyzed (subjective: the difference in the pressure of the wayfinding environment on the participants; objective: participants’ average speed, number of pauses, and the selection of infrastructure; systematic: ratings of affordance indicators). The results revealed that the mixed (vertical + horizontal) signage performed best, and different guidance signage designs affect passengers’ perception of environmental pressure, decision-making on the use of public infrastructures (stairs), and the number of pauses.
      Citation: Transportation Research Record
      PubDate: 2022-06-23T01:16:05Z
      DOI: 10.1177/03611981221103591
       
  • Decision-Making Framework for Prioritizing the Improvement of Pedestrian
           Facilities in Urban Areas Using Integrated Delphi, AHP, and TOPSIS
           Approach

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      Authors: Aromal V, Naseer MA
      Abstract: Transportation Research Record, Ahead of Print.
      The existing pedestrian facilities in urban areas can be improved by prioritizing the areas based on their infrastructure performance, location, safety, mobility, and liveability aspects. This paper aims to present a combination of Delphi, analytic hierarchy process (AHP), and Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) for prioritizing the improvement of pedestrian facilities in an urban area. The approach has been broken into three stages. Firstly, the significant factor assessment was done by the Delphi method. Secondly, AHP was applied to estimate the relative weightage of each factor. Finally, the TOPSIS method was used to rank the alternatives in preparation for the final decision. For better understanding, the proposed method was demonstrated by applying the framework in a case study. The analyses revealed that the proposed method is effective for prioritizing the improvement of pedestrian facilities in an urban area. The method described in this paper is intended to assist decision makers in ranking different sidewalk stretches in the urban areas that need to be improved based on various attributes. This paper makes a major impact by incorporating a novel approach for the decision making of pedestrian facilities improvement, which considered both subjective and objective judgments of multiple decision makers in the procedure at various stages using different multi-criteria decision making techniques. This approach can be combined with a scheduling methodology and optimization technique to increase the efficiency of the resource allocation process.
      Citation: Transportation Research Record
      PubDate: 2022-06-23T01:14:32Z
      DOI: 10.1177/03611981221103240
       
  • Decline in Traffic Congestion Increased Crash Severity in the Wake of
           COVID-19

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      Authors: Jonathan E. Hughes, Daniel Kaffine, Leah Kaffine
      Abstract: Transportation Research Record, Ahead of Print.
      Highway fatalities are a leading cause of death in the U.S. and other industrialized countries. Using highly detailed crash, speed, and flow data, we show highway travel and motor vehicle crashes fell substantially in California during the response to the COVID-19 pandemic. However, we also show the frequency of severe crashes increased owing to lower traffic congestion and higher highway speeds. This “speed effect” is largest in counties with high pre-existing levels of congestion, and we show it partially or completely offsets the “VMT effect” of reduced vehicle miles traveled on total fatalities. During the first eleven weeks of the COVID-19 response, highway driving decreased by approximately 22% and total crashes decreased by 49%. While average speeds increased by a modest 2 to 3 mph across the state, they increased between 10 and 15 mph in several counties. The proportion of severe crashes increased nearly 5 percentage points, or 25%. While fatalities decreased initially following restrictions, increased speeds mitigated the effect of lower vehicle miles traveled on fatalities, yielding little to no reduction in fatalities later in the COVID period.
      Citation: Transportation Research Record
      PubDate: 2022-06-23T01:13:38Z
      DOI: 10.1177/03611981221103239
       
  • Machine and Deep Learning Techniques for Daytime Fog Detection in Real
           Time with In-Vehicle Vision Systems Using the SHRP 2 Naturalistic Driving
           Study Data

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      Authors: Md Nasim Khan, Mohamed M. Ahmed
      Abstract: Transportation Research Record, Ahead of Print.
      The main focus of this study is to develop a system that can accurately detect the presence of fog in real time at a trajectory level. This study leveraged video data from the SHRP 2 Naturalistic Driving Study (NDS). Extensive data reduction steps were taken to classify various levels of foggy weather conditions from the video data to form two unique image data sets. Afterward, features based on the gray level co-occurrence matrix (GLCM) were extracted from the images and used as classification parameters for training support vector machine (SVM) and K-nearest neighbor (K-NN) algorithms. In addition, a convolutional neural network (CNN) was also examined to improve the detection performance. Although the analysis was done initially on a data set consisting of two weather conditions, clear and fog, it has been extended to include different levels of fog, that is, near fog and distant fog. While the accuracy of the first analysis with two categories was approximately 92% and 91% for SVM and K-NN classifiers, respectively, the CNN produced much greater accuracy of 99%. As expected, the accuracy of the second analysis, with more refined weather categories, was relatively lower than the first analysis where CNN, SVM, and K-NN models produced an accuracy of about 98%, 89%, and 88%, respectively. With the rapid advances in connectivity and affordable cameras, the proposed detection models could be integrated into the smartphones of regular road users, creating an effective way to collect real-time road weather information that could be used to improve weather-based variable speed limit (VSL) systems.
      Citation: Transportation Research Record
      PubDate: 2022-06-23T01:12:39Z
      DOI: 10.1177/03611981221103236
       
  • Traffic Noise Modeling of Short Safety Barriers

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      Authors: Dana M. Lodico
      Abstract: Transportation Research Record, Ahead of Print.
      Solid safety barriers are commonly constructed along highways. These barriers improve highway safety by preventing collisions and providing separation from slopes or adjacent hazards such as deep water. For elevated and at-grade roadways, these shorter barriers have also been shown to noticeably reduce traffic noise. In this study, modeling methods were developed and evaluated for their ability to accurately calculate the performance of short barriers in reducing traffic noise at the wayside. Five real-world highway scenarios were selected for model validation, including four sites located behind short safety barriers and a site located behind a short berm. Theoretical modeling was conducted to systematically evaluate the effects of modeling parameters on the prediction of noise reduction provided by short barriers.
      Citation: Transportation Research Record
      PubDate: 2022-06-23T01:11:19Z
      DOI: 10.1177/03611981221103234
       
  • Integrating Public Transit and Shared Micromobility Payments to Improve
           Transportation Equity in Seattle, WA

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      Authors: Kirsten Beale, Bogdan Kapatsila, Emily Grisé
      Abstract: Transportation Research Record, Ahead of Print.
      This study explores how shared micromobility services can integrate with public transit through equitable payment structures to address first and last mile issues for light rail transit riders in Seattle, WA, and increase accessibility for low-income households. Seattle has recently permitted shared micromobility services such as e-scooter companies to begin operating alongside existing bikesharing services in the city. However, equity concerns have arisen as the users of bikeshare have been disproportionately white, affluent, and well-educated. To address these concerns, efforts have been made to reduce barriers to access and make these services more equitable to encourage their use among marginalized populations. Previous research has demonstrated evidence that these services can improve accessibility for disadvantaged populations such as low-income people of color. This research consists primarily of a literature review of relevant academic and gray literature, and a jurisdictional scan of cities in the U.S., Canada, Finland, and China. The objective of this research is to identify barriers to accessing shared micromobility services and synthesize existing best practices to propose solutions to make these services more equitable. Findings from this research then inform a set of recommendations for equitable payment integration in King County, which can also be generalized to other municipalities that are striving for equitable public transit and shared micromobility integration.
      Citation: Transportation Research Record
      PubDate: 2022-06-23T01:10:13Z
      DOI: 10.1177/03611981221103233
       
  • Estimation of High-Frequency Auditory Masking in Beluga Whales by
           Commercial Vessels in Cook Inlet, Alaska

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      Authors: Justin Eickmeier, Jonathan Vallarta
      Abstract: Transportation Research Record, Ahead of Print.
      Industrial development in Cook Inlet, Alaska, has raised concerns about the decline of the resident beluga whale (Delphinapterus leucas) population over the past decades. Anthropogenic noise sources, such as commercial vessels, can cause auditory masking of cetacean vocalizations used in communication, navigation, and foraging. This study includes a source-level spectrum of a containership, positioned in Cook Inlet within the primary shipping channel, and audiograms obtained from a live, stranded beluga calf in Cook Inlet, in sound transmission loss modeling. The model uses a hybrid parabolic equation/raytracing solution to determine underwater sound pressure levels. Whereas the communication band of belugas can be fully masked by ambient noise and underwater radiated noise from a containership positioned at 5,000 m, the echolocation band (for navigation) is only partially masked at shorter ranges (≤2,500 m). Increased multipath reflections from the propagation of underwater noise in the upslope direction contributes significantly to the attenuation of high frequencies and minimizes masking in the echolocation band of the beluga whale. To assess the complex task of auditory masking, critical ratios were used to determine the difference between the energy of a pure tone and the noise in the masking band. A successful strategy to reduce underwater radiated noise must consider the interactions and contributions of mitigation measures that have already been shown to be effective. The technical and economic profitability of these measures will largely depend on the design, operating parameters, and mandatory requirements for a particular vessel.
      Citation: Transportation Research Record
      PubDate: 2022-06-23T01:09:14Z
      DOI: 10.1177/03611981221103230
       
  • Manual for Assessing Safety Hardware TL-4 Evaluation of Critical Flare
           Rate for Cast-in-Place Concrete Barrier

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      Authors: Maysam Kiani, Chiara Silvestri Dobrovolny, Roger Bligh, Chris Lindsey
      Abstract: Transportation Research Record, Ahead of Print.
      Concrete median barriers are used by Departments of Transportation (DOTs) to provide separation of traffic. Typically, the crashworthiness of these barriers is tested and evaluated in full-scale crash testing conducted according to current roadside safety device standards. Occasionally, DOTs need to flare the concrete barrier length of need (LON) around fixed objects, such as bridge piers. Flaring a concrete barrier increases the effective impact angle which consequently increases the impact severity of the vehicle creating an opportunity for vehicle instability or excessive occupant risk factors. No current recommendations are available to guide the installation of flared barriers around such fixed objects, while still maintaining barrier crashworthiness. Although the current practice is to flare the cast-in-place (CIP) concrete barrier at a maximum 20:1 rate, no full-scale crash testing has been conducted to determine the crashworthiness of the system at this condition or at a flare rate that might be considered more critical. The crash tests reported in this paper were performed according to the Manual for Assessing Safety Hardware (MASH) Tests 4–10 (with the use of a passenger car), 4–11 (a pickup truck), and 4–12 (a single unit truck) for LON, which represent the tests considered necessary to demonstrate the MASH compliance of the device. The 40-in. single slope CIP concrete barrier with a 20:1 flare rate met MASH requirements and is considered MASH compliant for Test Level (TL) 4. The system is considered suitable for implementation where there is a need to flare the concrete barrier around a fixed object.
      Citation: Transportation Research Record
      PubDate: 2022-06-22T07:27:22Z
      DOI: 10.1177/03611981221100527
       
  • Commuter Rail Electrifications That Never Were and What They Teach Us

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      Authors: John G. Allen, Gregory L. Newmark
      Abstract: Transportation Research Record, Ahead of Print.
      North American commuter railroads have experienced two waves of electrification: 1905–1931, and (including renewal and expansion) since the 1980s. Electrification offers many benefits to railroads and society, but also entails considerable capital costs. Eleven proposed electrifications, both in the early 20th century, when private-sector railroads funded and operated services, and in the modern era with public-sector responsibility for financing infrastructure and operations, were never implemented. This research revisits these unrealized proposals to understand the factors that can derail electrification and, conversely, help planners identify promising projects. These examples are explored in their contemporaneous context and in relation to comparable situations where electrification did occur. Key findings include that necessary, if not sufficient, conditions for electrification, in both the private- and public-sector eras, include operating challenges best addressed through electric traction as well as adequate funding. Today, in the public-sector era, electrification also requires political will, an institutional champion, and control of the lines to be electrified. Environmental concerns have become important factors but have not justified electrifications on their own.
      Citation: Transportation Research Record
      PubDate: 2022-06-22T07:22:24Z
      DOI: 10.1177/03611981221101028
       
  • Safety Margin Evaluation of Pedestrian Crossing through Critical
           Thresholds of Surrogate Measures of Safety: Area with Zebra Crossing
           versus Area without Zebra Crossing

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      Authors: Abbas Sheykhfard, Farshidreza Haghighi, Sarah Bakhtiari, Luigi Pariota
      Abstract: Transportation Research Record, Ahead of Print.
      Although many studies have been carried out on pedestrian crossing safety, comprehensive research evaluating vehicle–pedestrian conflict in areas with zebra crossing (AWZCs) versus areas without zebra crossing (AWOZCs) is still neglected. In the present study, through a naturalistic driving study (NDS), drivers’ behavior was recorded in AWZCs and AWOZCs. Vehicle–pedestrian conflicts were evaluated by examining the evasive maneuver behavior of drivers and pedestrians based on surrogate measures of safety (SMoS). The severity of conflicts was categorized by a K-means clustering method into three specific groups based on the critical thresholds of SMoS. The evasive maneuvers performed by pedestrians and drivers were classified into three levels: normal, slight, and serious. In conflicts resulting in normal and serious maneuvers, drivers would attempt to prevent collisions by changing the speed and direction of the vehicle. Moreover, a pedestrian at the slight level of conflict was the determinative factor in reducing the possibility of collisions by performing actions such as returning to the curb of the street or increasing walking speed. Also, the results showed that pedestrians were more likely to cross with a smaller margin of safety in AWOZCs than in AWZCs. This study explains how both pedestrians and drivers play a crucial role in preventing collisions during different levels of conflict. Given this finding, conducting future research to evaluate the interaction between drivers and pedestrians may lead to establishing a basic framework for designing an algorithm to detect the possibility of a pedestrian collision.
      Citation: Transportation Research Record
      PubDate: 2022-06-20T10:15:29Z
      DOI: 10.1177/03611981221099510
       
  • Investigation of Shifts in Time Use Behavior during the COVID-19 Pandemic:
           A Mixed Multiple Discrete-Continuous Extreme Value Approach with Panel GPS
           Data

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      Authors: Caroline Winkler, Aupal Mondal, Raphael Mesaric, Katherine Asmussen, Chandra Bhat, Kay W. Axhausen
      Abstract: Transportation Research Record, Ahead of Print.
      Typical patterns of time use and travel behavior have been transformed by the COVID-19 pandemic. The drastic change has been documented in several studies to date, especially in the realm of transport, which have asked respondents about how their behavior has changed compared with their prepandemic routines. This work complements those efforts, offering a valuable evaluation of the decision-making process behind choosing which activities to engage in and for how long. A mixed multiple discrete-continuous extreme value (MMDCEV) model was applied to panel GPS data collected between September 2019 and October 2020. The estimation results uncovered how different demographic and mobility tool ownership characteristics affected the choice of activities and their duration. Additional interaction effects of different time periods exogenously introduced into the model allowed for the assessment of the differential effects of these components. Our findings revealed that the choice to participate in out-of-home activities strongly differed with respect to prepandemic conditions. Not only were individuals choosing to spend more time at home during the pandemic, but when they did engage in out-of-home activities, it was also for a shorter duration. Notably, age, gender, education level, and income all affected the propensity to engage in out-of-home activities during the pandemic. These results and their implications for policy as we try to plan for the “new normal” daily life are discussed.
      Citation: Transportation Research Record
      PubDate: 2022-06-17T11:19:57Z
      DOI: 10.1177/03611981221099918
       
  • A Dynamic Aircraft Response Model for Determining Roughness Limits

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      Authors: Jeremiah M. Stache
      Abstract: Transportation Research Record, Ahead of Print.
      Runway roughness poses significant risks to aircraft and aircraft personnel. Roughness irregularities can be found in both civilian and military airfields, from rutting to bomb-damaged repairs. Various methods exist for determining roughness criteria, such as discrete surface deviation evaluation and dynamic response models. Although validated dynamic response models such as TAXI-G were used extensively in the HAVE BOUNCE program from the 1970s up to the late 1990s, modern military aircraft have not undergone the same formal analysis. This paper presents the mathematical formulation and validation of the WESTAX dynamic response model. The computer program is capable of simulating the responses of different critical aircraft components while trafficking over idealized runway profiles. The validation results showed that the numerical model was capable of closely matching field data over single- and double bump events. The findings suggest that the WESTAX dynamic response model is a capable candidate for establishing aircraft roughness limits.
      Citation: Transportation Research Record
      PubDate: 2022-06-17T11:17:36Z
      DOI: 10.1177/03611981221099280
       
  • Chronology of Service Limit State Development for Geotechnical Elements
           Designed Using AASHTO Load and Resistance Factor Design

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      Authors: Naresh C. Samtani, John M. Kulicki
      Abstract: Transportation Research Record, Ahead of Print.
      The purpose of this paper is to provide a chronology of the development of the Service Limit State design process for geotechnical elements that are designed using the reliability-based Load and Resistance Factor Design (LRFD) approach in the Bridge Design Specifications of AASHTO. This chronology will help future researchers to better understand the basis of decisions made by AASHTO, with input from the FHWA, and thus will serve as an important benchmark for future work.
      Citation: Transportation Research Record
      PubDate: 2022-06-17T11:14:50Z
      DOI: 10.1177/03611981221099017
       
  • Continuous Calibration Weigh-in-Motion System Using Static Weight Data

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      Authors: Douglas Pratt, Younhee Choi, Martin Plemel, A. T. Papagiannakis
      Abstract: Transportation Research Record, Ahead of Print.
      This paper presents an advanced approach for continuously calibrating weigh-in-motion (WIM) sorting systems using the static scale data generated by downstream truck inspection stations. It presents an automated closed-loop algorithm developed to accurately match vehicles at the two locations and use the data at the static weigh scale as the WIM calibration reference through a feedback algorithm. Calibration is carried out automatically by minimizing the error between WIM and static gross vehicle weight (GVW) measurements by vehicle class and speed. The large sample of vehicles involved in these calculations ensures high reliability in the calibration factors and the resulting accuracy in WIM measurements. The proof of concept is provided by analyzing data from eight multi-lane WIM systems in three States. It is demonstrated that the system can maintain indefinitely the accuracy of WIM systems in measuring GVW and axle loads without the need for periodic on-site calibrations involving test trucks.
      Citation: Transportation Research Record
      PubDate: 2022-06-17T11:12:13Z
      DOI: 10.1177/03611981221097402
       
  • Analyzing the Safety Consequences of Pedestrian Spatial Violation at
           Mid-Blocks: A Bayesian Structural Equation Modeling Approach

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      Authors: Haniyeh Ghomi, Mohamed Hussein
      Abstract: Transportation Research Record, Ahead of Print.
      The objective of this study is to understand the impact of a variety of factors on the frequency and severity of pedestrian-vehicle collisions that involve pedestrian spatial violations at mid-blocks. To that end, the historical collision records of the City of Hamilton between 2010 and 2017 were obtained, and collisions that had occurred at mid-blocks were filtered out. A Bayesian structural equation modeling (SEM) framework was developed to investigate the impact of a wide range of factors on such collisions. First, a classical SEM was developed to group the different factors into sets of latent variables. Four latent variables were defined, including location amenities and attractions, pedestrian/road network characteristics, exposure parameters, and location/collision-specific factors. The Bayesian SEM was then implemented to investigate the relationship between the latent variables and collisions. The results showed that the amenities and attractions of a location (e.g., parks, schools, bike-share stations, and bus stops) were the most influential factor on the frequency of collisions that involve spatial violation, followed by pedestrian network characteristics. Pedestrian network characteristics and location/collision-specific factors were found to be the most influential factors on the severity of collisions. The location of bike-share stations, pedestrian network connectivity, exposure to walkers, and the number of lanes were the four observed variables that explained the highest percentage of the variance in each latent group, respectively. The results of this study should assist engineers and planners to develop better design concepts to mitigate collisions that are caused by pedestrian spatial violations in urban areas.
      Citation: Transportation Research Record
      PubDate: 2022-06-17T04:29:50Z
      DOI: 10.1177/03611981221097964
       
  • Reliability Analysis of Bridges for Autonomous Truck Platoons

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      Authors: Sikandar Sajid, Luc Chouinard, Frederic Legeron, Todd Ude, Eddie He, Jack Ajrab
      Abstract: Transportation Research Record, Ahead of Print.
      Autonomous truck platoon (ATP) deployment on road networks has recently attracted significant interest for its potential economic and environmental benefits. However, the impact of platooning on bridges is a concern because of the differences in their live load characteristics compared with those in the existing bridge design specifications. One of the primary aspects in the safe deployment of ATP is to evaluate the reliability of bridge designed using the existing provisions for live loads from potential configurations of ATP. An analysis procedure is proposed and demonstrated for a simple span steel composite bridge designed according to the existing design provisions. Given that many characteristics of the live load distribution such as the bias factor, coefficient of variation (CoV), and the dynamic amplification factor are presently not known for ATP, a parametric approach is used. The bias factor, dynamic amplification, and CoV are parametrized to calculate the live load distribution and quantify its impact on the reliability index. A two-truck platoon with different headway spacings constituted by different trucks in a single lane scenario is considered. The results indicate that the two single lane bridges designed according to existing design specifications are generally reliable (i.e., achieved the target reliability for which the bridge was initially designed) for the range of ATP live loads investigated when the CoV is less than 0.07, bias close to one and headway distances are above 17 ft. Future studies are suggested to include bridges with multiple spans, other bridge types, and a larger number of trucks in the platoons. The main contribution of this paper is to quantify the reliability indices of selected steel composite bridges designed using the existing specifications but subjected to various configurations of ATP loads and the influence of different components of the live load model attributed to the latter.
      Citation: Transportation Research Record
      PubDate: 2022-06-15T09:16:42Z
      DOI: 10.1177/03611981221103235
       
  • Adding Multi-Day Attributes for Ridesharing Simulations via Data Fusion

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      Authors: Iván Mendoza, Chris M. J. Tampère
      Abstract: Transportation Research Record, Ahead of Print.
      Evaluating ridesharing potential is a trend in current research efforts because ridesharing provides additional mobility alternatives without extra putting vehicles on the road. Nevertheless, in most studied scenarios, the demand revealed by surveys and demographic information does not include multi-day characteristics of a trip such as frequencies on weekdays. Yet this is important for estimating the supply of rides, as the recurrence or regularity of a trip may affect the likelihood of a driver making the effort of registering the trip as being available for sharing. Likewise, if automated apps are used to recognize patterns in one’s trips and pro-actively offer them for sharing, the successful anticipation of such apps may again depend on the regularity of the trip. However, since multi-day data are complex to produce, in this paper, a data fusion procedure is proposed to generate an enriched synthetic demand for more realistic assessments. This can be achieved by combining standard single-day data sets with travel behavior patterns, which can be extracted from lifelogging data collected by most existing mobile apps. The resulting data sets after transferring information from the travel patterns to a recipient data set via statistical matching, will constrain matching trips by multi-day characteristics allowing complex scenarios. This approach enhances the evaluation of ridesharing and other shared-mobility systems and thus their ability to plan better strategies.
      Citation: Transportation Research Record
      PubDate: 2022-06-15T09:10:22Z
      DOI: 10.1177/03611981221101618
       
  • Framework for Quantifying Right-Turn-on-Red Conflicts From Existing
           Radar-Based Vehicle Detection Infrastructure

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      Authors: Hiba Nassereddine, Kelvin R. Santiago-Chaparro, David A. Noyce
      Abstract: Transportation Research Record, Ahead of Print.
      Surrogate safety measures (SSMs) have been used as an alternative to crash-based methods to study road safety. This study proposes a framework to estimate SSMs, such as post encroachment time (PET) and time to collision (TTC) values between right-turn-on-red (RTOR) and through vehicles, and demonstrates the feasibility of using vehicle trajectories obtained from existing radar-based vehicle detection systems to calculate such measures. The framework was implemented by the research team using a software-based approach. The framework presented consists of three stages: first, noise removal and classification of vehicles per lane; second, pairing RTOR vehicles and conflicting-through vehicles; and third calculation of PET and TTC values for each interaction using the radar-based vehicle trajectory dataset. Using video recordings, the interactions between right-turning vehicles and conflicting-through vehicles were documented and key vehicle position timestamps were logged. Logged timestamps enabled the calculation of PET. Video recordings acted as a tool to verify the results of PET calculations based on radar-based vehicle trajectory data. Therefore, the validity of the automated calculation of PET based on radar-based vehicle trajectory data was confirmed using the video recordings from the data collection site. The proposed framework demonstrates the potential to expand the capabilities of existing vehicle detection infrastructure to support proactive safety evaluations at a system level and increase the return on investment on existing vehicle detection technology. The proposed framework can be used in the development of safety models using existing vehicle detection infrastructure based on radar technology without the need for image processing techniques or specialized hardware.
      Citation: Transportation Research Record
      PubDate: 2022-06-15T09:06:38Z
      DOI: 10.1177/03611981221094287
       
  • Quantitative Derailment Rate Comparison of Unit Trains at Transload
           Terminals and Manifest Trains at Railroad Switching and Hump
           Classification Yards

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      Authors: Jiaxi Zhao, C. Tyler Dick
      Abstract: Transportation Research Record, Ahead of Print.
      The rapid expansion of demand for efficiently and safely transporting crude oil and other flammable liquids by rail in North America has highlighted the need to understand the relative derailment risk of two main freight train types operating in the United States (U.S.): unit trains and manifest trains. Previous studies have quantified the line-haul accident rates for these train types. However, the relative derailment likelihood of these two train types associated with train arrival/departure processes and yard switching operations has yet to be quantified. This study analyzes U.S. freight train traffic and yard/terminal derailment data between 1996 and 2018 by train type. For manifest trains, derailment rates are calculated per train arrival and departure in yards, and yard switching accidents per railcar handled in classification yards. For unit trains, the number of accidents per arrival and departure event in loading and unloading terminals is quantified. These rates are further refined to reflect particular unit train loading conditions and yard type for manifest trains. The analyses suggest that manifest trains have a four-times larger rate per yard arrival/departure than unit trains per terminal arrival/departure. Regardless of yard type, railcar shunting movements in classification yards are significant to the overall manifest train shipment derailment likelihood. An example case study demonstrates how a manifest train may be ten times more likely to derail than a unit train, while varying the number and type of intermediate yards for manifest train and the loading factor for unit train has distinct impacts on the overall derailment rate.
      Citation: Transportation Research Record
      PubDate: 2022-06-15T09:01:00Z
      DOI: 10.1177/03611981221099287
       
  • New Mobility-Assist E-Grocery Delivery Network: a Load-Dependent
           Two-Echelon Vehicle Routing Problem With Mixed Vehicles

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      Authors: Dan Liu, Hao (Frank) Yang, Xinhua Mao, Vasileia Antonoglou, Evangelos I. Kaisar
      Abstract: Transportation Research Record, Ahead of Print.
      New forms of transport, such as autonomous delivery robots (ADRs), have attracted considerable attention in recent years for their potential use as green last-mile delivery alternatives because of their flexibility in some areas unreachable by van. However, their low efficiency, delivering a limited number of orders each trip, limits their application in the last mile. Also, the cost and emission impact of new forms of transport on the last-mile delivery network is still not clear. To address these issues, we developed a new two-echelon delivery system that combines traditional vans and ADRs, making use of their individual advantages to overcome their drawbacks and enhance efficiency in the deliveries. The objective of this study was to develop a new approach based on a metaheuristics methodology to minimize transport and emission costs through modeling and to solve the extension of two-echelon load-dependent vehicle routing problems with mixed vehicles (2E-LDVRP-MV). The complicated 2E-LDVRP-MV problem was formulated as a mixed-integer programming (MIP) model and solved efficiently with a cluster-based artificial immune algorithm (C-AIA) in which clustering was employed to allocate customers. We performed a set of numerical experiments with a solver and the proposed C-AIA heuristics. C-AIS highlights the operational implications of four parameters: ratios between load and the empty vehicle weight; vehicle types; emission levels; and customer densities. Our results provide a unique perspective on tactical planning for a sustainable urban logistics system, and this new two-echelon system could be applied in e-grocery last-mile delivery networks where vans and ADRs are combined.
      Citation: Transportation Research Record
      PubDate: 2022-06-15T08:58:56Z
      DOI: 10.1177/03611981221099277
       
  • Accelerating Adoption of Disruptive Technologies: Impact of COVID-19 on
           Intentions to Use On-Demand Autonomous Vehicle Mobility Services

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      Authors: Maher Said, Emma R. Zajdela, Amanda Stathopoulos
      Abstract: Transportation Research Record, Ahead of Print.
      One of the most notable global transportation trends is the accelerated pace of development in vehicle automation technologies. Uncertainty surrounds the future of automated mobility as there is no clear consensus on potential adoption patterns, ownership versus shared use status, and travel impacts. Adding to this uncertainty is the impact of the COVID-19 pandemic which has triggered profound changes in mobility behaviors as well as accelerated the adoption of new technologies at an unprecedented rate. Accordingly, this study examines the impact of the COVID-19 pandemic on people’s intention to adopt the emerging technology of autonomous vehicles (AVs). Using data from a survey disseminated in June 2020 to 700 respondents in the United States, a difference-in-difference regression is performed to analyze the shift in willingness to use AVs as part of an on-demand mobility service before and during the pandemic. The results reveal that the COVID-19 pandemic had a positive and highly significant impact on the intention to use AVs. This shift is present regardless of tech-savviness, gender, or urban/rural household location. Results indicate that individuals who are younger, politically left-leaning, and frequent users of on-demand modes of travel are expected to be more likely to use AVs once offered. Understanding the systematic segment and attribute variation determining the increase in consideration of AVs is important for policy making, as these effects provide a guide to predicting adoption of AVs—once available—and to identify segments of the population likely to be more resistant to adopting AVs.
      Citation: Transportation Research Record
      PubDate: 2022-06-15T08:55:29Z
      DOI: 10.1177/03611981221099276
       
  • Health Care Logistics Network Design and Analysis on Pandemic Outbreaks:
           Insights From COVID-19

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      Authors: Zeynep Cetinkale, Nezir Aydin
      Abstract: Transportation Research Record, Ahead of Print.
      Health care systems throughout the world are under pressure as a result of COVID-19. It is over two years since the first case was announced in China and health care providers are continuing to struggle with this fatal infectious disease in intensive care units and inpatient wards. Meanwhile, the burden of postponed routine medical procedures has become greater as the pandemic has progressed. We believe that establishing separate health care institutions for infected and non-infected patients would provide safer and better quality health care services. The aim of this study is to find the appropriate number and location of dedicated health care institutions which would only treat individuals infected by a pandemic during an outbreak. For this purpose, a decision-making framework including two multi-objective mixed-integer programming models is developed. At the strategic level, the locations of designated pandemic hospitals are optimized. At the tactical level, we determine the locations and operation durations of temporary isolation centers which treat mildly and moderately symptomatic patients. The developed framework provides assessments of the distance that infected patients travel, the routine medical services expected to be disrupted, two-way distances between new facilities (designated pandemic hospitals and isolation centers), and the infection risk in the population. To demonstrate the applicability of the suggested models, we perform a case study for the European side of Istanbul. In the base case, seven designated pandemic hospitals and four isolation centers are established. In sensitivity analyses, 23 cases are analyzed and compared to provide support to decision makers.
      Citation: Transportation Research Record
      PubDate: 2022-06-15T08:53:41Z
      DOI: 10.1177/03611981221099015
       
  • Effects of Road Marking Visibility on Vehicles Driving Along Curves: A
           Preliminary Study in a Simulated Environment

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      Authors: Gaetano Bosurgi, Stellario Marra, Orazio Pellegrino, Giuseppe Sollazzo, Massimo Villari
      Abstract: Transportation Research Record, Ahead of Print.
      The role of road markings is fundamental for traffic safety, as it represents an essential optical driving instrument both for effective drivers and autonomous vehicles. This research aims to evaluate the effects of the decay of road marking visibility along curves, specifically the variability in lateral acceleration. Traditionally, issues related to the correct interpretation of a road alignment were studied by means of trajectory analyses. However, they involved information about the vehicle’s geometrical position without any indication on dynamics. To explore this aspect further, an experiment in a simulated environment involving 21 drivers was performed. They drove along a test road in a standardized scenario considering only three variables: the curve direction (right or left), the deviation angle (70° or 30°), and the road marking visibility percentage (100%, 50%, 10%, and 0%). The results, in differences between theoretical (depending on design speed and curve radius) and effective lateral accelerations, provide further evidence of the strategic role of the markings. However, when markings deteriorate, drivers activate some balancing mechanisms to mitigate the dynamic effects along curves and, in turn, to improve comfort and safety. The proposed procedure is not only of direct practical interest, but it is also fully generalizable to other contexts and issues, involving several other elements that may influence the phenomenon, such as road geometry, visibility conditions, and traffic flow speed.
      Citation: Transportation Research Record
      PubDate: 2022-06-15T08:44:29Z
      DOI: 10.1177/03611981221097095
       
  • Identification of Subway Track Irregularities Based on Detection Data of
           Portable Detector

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      Authors: Run Liu, Fu-Tian Wang, Zhi-Peng Wang, Cui-Lin Wu, Hong-Di He
      Abstract: Transportation Research Record, Ahead of Print.
      At present, the detection of subway track irregularities is mainly carried out by track inspection vehicles and track inspection trolleys. Such detections are restricted by subway service time, so they can only be carried out once every few months. This study explored the possibility of using the vibration of the vehicle body collected by a novel portable detector to detect track geometry irregularities. It makes a particular contribution to the dynamic detection of track conditions and the reduction of maintenance costs. Based on the data collected by the portable detector, wavelet transform was used to analyze the vibration of the vehicle body. The results confirmed that this method was effective in enhancing the correlation between vibration accelerations and track irregularities. Second, a data set processed by wavelet transform was resampled by a hybrid sampling method which uses clustering methods and considers data imbalance within each category. In this way, the imbalance ratio of the data set was found to be reduced without changing the original data set structure. Finally, the random forest algorithm and the gradient boost decision tree algorithm were adopted for classifying track regularity and irregularity data. The results showed that both two algorithms, especially the random forest algorithm, performed well for the longitudinal level track irregularity and the alignment track irregularity.
      Citation: Transportation Research Record
      PubDate: 2022-06-15T08:33:45Z
      DOI: 10.1177/03611981221097088
       
  • Hazard Perception in Driving: A Systematic Literature Review

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      Authors: Shi Cao, Siby Samuel, Yovela Murzello, Wen Ding, Xuemei Zhang, Jianwei Niu
      Abstract: Transportation Research Record, Ahead of Print.
      Hazard perception (HP) is the process of detecting and identifying hazards. Drivers’ HP abilities are critical for driving safety. This paper presents a systematic literature review of driver HP, including scientific measures of HP, major human factors affecting HP, and training methods for improving HP skills. Sixty-nine peer-reviewed studies were identified and reviewed. The results showed that common measures of HP include hazard scenario questionnaires, HP reaction time, hazard hit rate, and eye fixation measures such as fixation probability, fixation reaction time, fixation duration, and fixation variance. Major human factors that affect HP include experience, aging, fatigue, distraction, and the use of alcohol and drugs. Various training methods have been developed to train and improve drivers’ HP skills. In general, there is evidence in the literature showing the effectiveness of HP training. A combination of complementary training approaches such as instruction, expert demonstration, and active practice with feedback and attention support the use of picture-, video-, computer-, and simulator-based training methods to improve HP performance in shorter HP reaction time, higher hazard hit rate, and better eye scan patterns (more spread scan, more anticipatory scan). These findings could guide future work developing and designing HP training programs. Three future research areas are identified and discussed: the need for standardized HP tests, long-term testing of HP training programs, and new HP questions and challenges brought by partially automated vehicles.
      Citation: Transportation Research Record
      PubDate: 2022-06-15T08:31:10Z
      DOI: 10.1177/03611981221096666
       
  • Impact of Different Penetration Rates of Shared Autonomous Vehicles on
           Traffic: Case Study of Budapest

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      Authors: Issa Matalqah, Mohamad Shatanawi, Anas Alatawneh, Ferenc Mészáros
      Abstract: Transportation Research Record, Ahead of Print.
      The accelerating emergence of vehicle automation and the anticipation of the advent of shared mobility through fully autonomous vehicles indicate the beginning of a new era of mobility which has the potential to reshape the future of transport in urban areas. In light of such developments, it is important that communities prepare to adapt to the changes they might entail. Therefore, in this paper, traffic flow theory, simulation-based dynamic traffic assignment, and a computer experiment using PTV Visum software were employed to study the impact of different market penetration rates of shared autonomous vehicles (SAVs) on a city-size traffic system. The city of Budapest during morning peak period was chosen as a case study, and a simulation model was created by incorporating SAV elements and their interrelationships into the existing traffic model of the case study city; three alternative future penetration rates were examined in relation to five key performance indicators (KPIs). The simulation results indicated that the implementation of the SAV system has a positive effect on traffic performance. Based on the relationships between the modeled SAV demand shares and the network’s KPIs in the designed scenarios, the overall network performance showed improvement along with an increase in the SAV demand share.
      Citation: Transportation Research Record
      PubDate: 2022-06-15T07:32:03Z
      DOI: 10.1177/03611981221095526
       
  • Comprehensive Framework and Roadmap for Life-Cycle Management of
           High-Friction Surface Treatments

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      Authors: Cibi Pranav, Yi-Chang Tsai
      Abstract: Transportation Research Record, Ahead of Print.
      High-friction surface treatments (HFSTs) are increasingly being applied at critical roadway locations (such as horizontal curves) that have high friction demand and a history of wet crashes; well-constructed HFST on sound underlying pavements has generally provided durable high friction. However, HFST friction loss because of aggregate loss or other distresses is a serious safety concern. HFST installation and management, especially its safe application and operation, involves different life-cycle activities (site selection and planning, construction, performance monitoring, maintenance, and replacement). These life-cycle activities involve complex and challenging technical components (including site selection criteria, construction quality control, performance measures, maintenance trigger criteria, etc.). To effectively manage the complex and challenging components of HFST and to mitigate safety concerns, this paper (a) studied the current challenges and identified the technical and management needs for safely managing HFST pavements based on a literature review, a national survey, and interviews with experts, (b) developed a comprehensive technical and managerial integrated framework to manage network-level safety throughout HFST’s life-cycle activities by synthesizing the core contents of the identified needs, and (c) proposed a roadmap containing research, development, and deployment actions needed for enhancing HFST management practices. The developed comprehensive framework enables researchers and Departments of Transportation to holistically see the different components of HFST life-cycle activities so that HFST can be managed systematically and cost-effectively while ensuring safety. This framework can also be used as a checklist of items for transportation agencies to follow to ensure high-quality and effective HFST installation and management.
      Citation: Transportation Research Record
      PubDate: 2022-06-15T07:30:43Z
      DOI: 10.1177/03611981221095517
       
  • On the Analytical Probabilistic Modeling of Flow Transmission Across Nodes
           in Transportation Networks

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      Authors: Jing Lu, Carolina Osorio
      Abstract: Transportation Research Record, Ahead of Print.
      This paper focuses on the analytical probabilistic modeling of vehicular traffic. It formulates a stochastic node model. It then formulates a network model by coupling the node model with the link model of Lu and Osorio (2018), which is a stochastic formulation of the traffic-theoretic link transmission model. The proposed network model is scalable and computationally efficient, making it suitable for urban network optimization. For a network with [math] links, each with a space capacity of one, the model has a complexity of [math]. The network model yields the marginal distribution of link states. The model is validated versus a simulation-based network implementation of the stochastic link transmission model. The validation experiments consider a set of small networks with intricate traffic dynamics. For all scenarios, the proposed model accurately captures the traffic dynamics. The network model is used to address a signal control problem. Compared with the probabilistic link model of Lu and Osorio (2018) with an exogenous node model and a benchmark deterministic network loading model, the proposed network model derives signal plans with better performance. The case study highlights the added value of using between-link (i.e., across-node) interaction information for traffic management and accounting for stochasticity in the network.
      Citation: Transportation Research Record
      PubDate: 2022-06-15T07:28:26Z
      DOI: 10.1177/03611981221094829
       
  • Investigation into the Impact of Weight on Diesel Trucks’ NOx Emissions:
           An Overweight Case Study

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      Authors: Reza Farzaneh, Jeremy Johnson, Jolanda Prozzi, Rohit Jaikumar, Madhu Venugopal
      Abstract: Transportation Research Record, Ahead of Print.
      To build an understanding of the emission contribution, especially nitrogen oxides (NOx) emissions, of many overweight/oversized trucks operating in the Dallas-Fort Worth area, U.S., the North Central Texas Council of Governments commissioned the Texas A&M Transportation Institute to conduct an emission testing study. The study team collected and analyzed data on these vehicles’ activities and emissions characteristics. Vehicle activity data collection was performed using portable activity measurement systems, and exhaust emissions data was measured using two portable emission measurement systems. Using methodologies developed by the Environmental Protection Agency for the MOtor Vehicle Emissions Simulator (MOVES) model, both datasets were processed and expressed as emission rates for three loading scenarios. Researchers observed that, because of the sensitivity of the performance of selective catalytic reduction (SCR) to exhaust temperature, NOx data observed during a test cycle may not result in emission rates that are representative of the real-world operations. The team developed a methodology to adjust the resulting NOx rates for SCR-equipped trucks. The findings of the analysis suggest that the current MOVES opMode equations do not appear to adequately capture the impact of weight on the emission rates of heavy-duty diesel vehicles. The team also found that SCR-equipped trucks can have lower emission rates under heavier loads, especially in higher-speed and higher-power opMode bins, which typically have higher exhaust temperatures. Under normal loads (approximately 55,000 lb), SCR does not seem to provide a NOx emission reduction benefit at speeds under 50 mph compared with exhaust gas recirculation-equipped trucks.
      Citation: Transportation Research Record
      PubDate: 2022-06-15T07:26:25Z
      DOI: 10.1177/03611981221094827
       
  • Parking Planning With Route Assignment for Planned Special Events

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      Authors: Yujing Zheng, Jing Cao, Yu Shen, Bing Liu, Yuxiong Ji
      Abstract: Transportation Research Record, Ahead of Print.
      During a planned special event (PSE), vehicular and pedestrian movements are concentrated around the PSE venue for short periods, leading to potential conflicts and safety issues. Vehicles tend to park as close as possible to the venue for the convenience of attendees. Taking into account the characteristics of PSE traffic patterns, a strategic vehicle parking planning model is proposed to integrally optimize the assignment of parking lots and inbound/outbound routes around the venue. Two prioritized objectives were considered for traffic safety and for the convenience of attendees. The proposed model was first validated in a small-scale example, and then adopted in a real-world case that took place in Taiyuan, China. The resulting parking plan presented an efficient reduction in the conflict points between vehicular and pedestrian movements, leading to an acceptable average walking distance for attendees. To evaluate the impact of different management preferences on the parking plan, a series of weights for conflict points were set according to potential conflict locations, occurrence times, and types. The results demonstrated that the number of conflict points with higher weights could be effectively reduced by the parking plan.
      Citation: Transportation Research Record
      PubDate: 2022-06-15T07:24:23Z
      DOI: 10.1177/03611981221098696
       
  • Innovative Strategy Development Approach for Enhancing the Effective
           Implementation of the International Safety Management (ISM) Code

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      Authors: S. M. Esad Demirci, Kadir Cicek
      Abstract: Transportation Research Record, Ahead of Print.
      Maritime transport is a rule-intensive mode of transport. Maritime accidents continue to occur, however, and the catastrophic consequences of such accidents means that maritime transport safety continues to be an important subject. The International Safety Management (ISM) Code is one of the most important steps taken to prevent accidents and enhance shipping safety with the establishment of the safety management system (SMS). However, the important point is not only the establishment of the SMS but also the effective implementation of the ISM Code. To improve the effective implementation of the ISM Code, an innovative strategy development approach has been developed with the integration of Decision-Making Trial and Evaluation Laboratory (DEMATEL) and Theory of Inventive Problem Solving (TRIZ) methodologies. In the study, causal relationships between ISM Code clauses are mainly analyzed with the DEMATEL method. Subsequently, using the results obtained from the analysis of the causal relationships, potential strategies to improve the effective implementation of the ISM Code are presented by using the TRIZ method. The findings of the paper could provide beneficial outcomes for shipping companies and national and international regulatory bodies to enhance maritime transport safety by improving the effectiveness of implementation of the ISM Code.
      Citation: Transportation Research Record
      PubDate: 2022-06-15T07:22:16Z
      DOI: 10.1177/03611981221098394
       
  • Behavior Decision Model With Situation Assessment for Intelligent Vehicles
           Based on Vehicle-to-Everything Information

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      Authors: Runde Zhang, Shaowu Zheng, Weihua Li
      Abstract: Transportation Research Record, Ahead of Print.
      Under the application of cooperative vehicle infrastructure technology, vehicles can drive more safely and efficiently in urban traffic environments. This paper presents a behavior decision model composed of a situation assessment module and decision process module to make a decision on lane selection and velocity control. Different common traffic elements are considered, such as surrounding obstacles, traffic lights, lane lines, and road velocity limits, to ensure the model outputs safe and legal behaviors. A green-wave passage strategy is also proposed to allow vehicles to pass through traffic intersections at a smoother velocity and to improve driving efficiency. To verify the correctness and rationality of the model, a Prescan/Simulink co-simulation platform including multiple common urban driving scenarios is established. The results show that the model can output correct behaviors with safety and legitimacy in different scenarios and realize vehicles meeting at intersections, vehicle-following, queuing at intersections with traffic lights, lane-changing for obstacle avoidance, and so forth. Compared with the general decision model without the green-wave passage strategy, the driving time is reduced by an average of 8.53%, and the standard deviation of the driving velocity is reduced by an average of 65.42%, which means that the model can reduce the variation of velocity and improve driving efficiency. The model has a certain practical application value.
      Citation: Transportation Research Record
      PubDate: 2022-06-15T07:20:43Z
      DOI: 10.1177/03611981221094001
       
  • Analysis of Travelers’ Risk Perceptions About Public Transit Systems
           During COVID-19 Pandemic

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      Authors: B Raghuram Kadali, Surya SSR Gadiraju, Hari Krishna Gaddam
      Abstract: Transportation Research Record, Ahead of Print.
      The epidemic novel coronavirus disease 2019, abbreviated as COVID-19, has changed people’s mobility choices significantly, which has had a great impact on public transportation because of the public’s risk perception. The pandemic forced many people to shift toward private transport modes, which resulted in a decrease in public transport ridership and significantly altered travel behavior in urban areas. In this context, the present study investigated the public’s COVID-19 risk perception when public transportation is used (i.e., risk-taking behavior) and factors that significantly affect the use of public transportation. To fulfill this objective, a Google form-based questionnaire was prepared and circulated online. A total of 1,720 responses were collected using the survey form. These responses were processed for outliers and incomplete responses, and a total of 1,486 data samples were used for the analysis. A factor-based regression model was developed to study the risk-taking behavior of travelers while using public transportation during the COVID-19 pandemic. From the analysis, it is inferred that the travelers’ attitude negatively correlated with risk-taking behavior, whereas technology, motivation, concerns, and education positively affected COVID-19 risk perception when using public transit. Further, the study concluded that the behavior of travelers has a significant impact on their risk-taking behavior through their attitude and social norms. The findings of this study will be useful to urban transport planners in making suitable policies to increase public transportation ridership during pandemics.
      Citation: Transportation Research Record
      PubDate: 2022-06-15T07:18:50Z
      DOI: 10.1177/03611981221093332
       
  • Identification and Comparative Safety Analysis of Overtaking Patterns on
           Two-Lane Highways: A Simulator Study With Novice Drivers

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      Authors: Rui Zhang, Qiong Bao, Kris Brijs, Elke Hermans, Yongjun Shen
      Abstract: Transportation Research Record, Ahead of Print.
      Overtaking on two-lane highways is one of the riskiest driving maneuvers. However, safety analysis technologies for overtaking patterns and trajectories require development. In this simulator study, 328 overtaking trajectories were collected from 52 novice drivers to analyze difference in overtaking safety performances on two-lane highways under different traffic conditions. Two analyses were conducted: Analysis I focused on structural trajectory differences and classified the trajectory sample into two patterns—“ladder” (LAT) and “triangle” (TRT). In Analysis II, a comparative safety evaluation method was established based on data envelopment analysis to compare overtaking pattern safety; a factor analysis of the safety performance was undertaken by means of ordinary regression models. We found that TRT had a lower spatial consumption and smoother trajectory than LAT, but drivers overtaking using TRT were exposed to higher risk than LAT. Certain environmental and human factors had an influence on the safety levels of the patterns: both deteriorated when drivers were surrounded by vehicles driving at higher speeds, and improved with longer passing sight distances. However, safety levels when overtaking trucks were significantly worse than overtaking cars in the LAT pattern—the opposite was found for TRT. Female drivers’ safety performance was superior in the LAT pattern; no significant gender difference were found with TRT. A longer following distance was found to ameliorate the safety of the TRT pattern, with no effect on LAT. These findings aid understanding of overtaking maneuvers on two-lane highways, and provide recommendations for advanced assistance driving and automatic driving systems.
      Citation: Transportation Research Record
      PubDate: 2022-06-15T07:13:56Z
      DOI: 10.1177/03611981221100240
       
  • Cross-Cultural Investigation of the Effects of Explanations on Drivers’
           Trust, Preference, and Anxiety in Highly Automated Vehicles

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      Authors: Na Du, Lionel Robert, X. Jessie Yang
      Abstract: Transportation Research Record, Ahead of Print.
      This study explored, in consideration of cultural differences, how explanation timing and permission of the automated vehicle’s (AV’s) actions affected drivers’ trust in, preference for, and anxiety about the AV. We conducted a video-based online survey study with 118 participants in different cultural contexts. Each participant experienced four conditions in highly automated driving: (1) no explanations, (2) explanations given before, or (3) after the AV acted, and (4) the option for drivers to approve or disapprove the AV’s action after explanations. We found that context cultures influenced drivers’ trust in and preference for the AV only when explanations were provided. Participants with higher-context cultures had higher trust in and preference for the AV. Such influence was augmented especially when the AV asked for permission after explanations. Our results have important implications for the design of in-vehicle interfaces. We suggest that AV manufacturers should incorporate cultural differences into AV explanation interface design for global use.
      Citation: Transportation Research Record
      PubDate: 2022-06-15T07:12:12Z
      DOI: 10.1177/03611981221100528
       
  • Safety Evaluation of Freeway Exit Ramps with Advisory Speed Reductions

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      Authors: Megat Usamah Megat Johari, Nusayba Megat Johari, Peter T. Savolainen, Timothy J. Gates
      Abstract: Transportation Research Record, Ahead of Print.
      Posted speed limits inform drivers of the legal maximum allowable speed. In contrast, advisory speeds provide recommendations to drivers based on highway design, operating characteristics, and conditions. Various studies have investigated the safety impacts of speed limit changes, particularly on high-speed rural highways. One area of particular concern on such roadways is the approach to exit ramps that require substantive speed reductions, such as loop ramps. To date, there has been limited research examining the safety impact of the differential between the mainline speed limit and the lower exit ramp advisory speeds. This study aims to evaluate this relationship through the estimate of a series of safety performance functions. Random effects negative binomial regression models were estimated using data from 187 exit ramps where advisory speed signs are present throughout Michigan. The analyses were conducted based on a five-year period from 2014 to 2019, excluding 2017 data because of speed limit increases. In addition to speed differentials, various roadway characteristics such as deceleration lane length and curve radius were also evaluated. Results indicate that crashes increased as the difference between mainline and ramp speed increased. Crashes were also shown to decrease on ramps where the upstream deceleration lane length was greater than the minimum recommendation as per current design guidance.
      Citation: Transportation Research Record
      PubDate: 2022-06-15T07:10:13Z
      DOI: 10.1177/03611981221099908
       
  • Comparative Study of Pavement Rehabilitation Using Hot in-Place Recycling
           and Hot-Mix Asphalt: Performance Evaluation, Pavement Life Prediction, and
           Life Cycle Cost Analysis

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      Authors: Yuetan Ma, Pawel Polaczyk, Miaomiao Zhang, Rui Xiao, Xi Jiang, Baoshan Huang
      Abstract: Transportation Research Record, Ahead of Print.
      The use of hot in-place recycling (HIR) for pavement surface rehabilitation has gained increasing attention in recent years with the aim of achieving sustainable pavement. For the purpose of cost saving and the consumption of 100% reclaimed asphalt pavement (RAP), an in-place HIR train has been developed to combine various units including preheating, milling, rejuvenating, and compacting. Compared with the conventional hot-mix asphalt (HMA) surface treatment, the HIR technique might result in different pavement performances as a result of the low mixing temperature and insufficient quality control. This study aimed to conduct a comparative analysis of pavement surface rehabilitation using HIR and HMA, including the performance evaluation, pavement life prediction, and life cycle cost analysis (LCCA). HIR and HMA mixes were collected from construction areas and the nearby asphalt plant, respectively. The loose mixes were reheated and compacted for performance testing, including dynamic modulus tests, Superpave IDT tests, and moisture susceptibility tests. The AASHTOWare Pavement ME Design software was adopted to predict the pavement life with two rehabilitation techniques, followed by the LCCA with regard to the prediction results. Test results showed that pavement surface rehabilitation with HIR achieves acceptable performance and economic benefits. However, the HIR mixes are brittle and more susceptible to cracking and, therefore, have shorter pavement service lives than HMA.
      Citation: Transportation Research Record
      PubDate: 2022-06-15T07:09:19Z
      DOI: 10.1177/03611981221099907
       
  • Spatiotemporal Variation of Traffic Conflict at Signalized Intersections
           under Non-Lane-Based Traffic Condition

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      Authors: A Shahana, Vedagiri Perumal
      Abstract: Transportation Research Record, Ahead of Print.
      The majority of accidents observed at signalized intersections comprise rear-end collisions resulting from a diversity of actions happening during signal change. This study explores the spatial and temporal variation of rear-end conflict in non-lane-based multi-class traffic conditions. Precise positions of the vehicles extracted from traffic video data collected from two major cities in India are utilized to identify critical vehicle interactions. Multiple surrogate safety measures (time to collision and deceleration rate to avoid crash) are used to identify the rear-end conflicts. More than 9,000 vehicle trajectories extracted from four signalized intersections were used to develop heat maps showing space-time variation of rear-end conflict at varying threshold values. Results showed that the majority of rear-end conflicts happened at the beginning of red time and green time at the upstream side of signalized intersections. Separate heat maps were developed to explore the variation in rear-end conflict caused by different vehicle types and lateral movement of vehicles. In addition, this study develops conflict-based safety models to investigate how changes in traffic parameters including traffic volume, vehicle speed, platoon ratio, queue length, and signal control affect the conflict hotspot (most intense conflict location) at the signalized intersections. The results showed that the higher the vehicle speed and queue length the greater the shift of the conflict hotspot away from the stop line in the upstream direction. The developed models can give insight into how changes in the traffic parameters and the signal cycle time affect the safety of signalized intersections.
      Citation: Transportation Research Record
      PubDate: 2022-06-14T10:53:05Z
      DOI: 10.1177/03611981221099288
       
  • Dynamic Bus Lanes Versus Exclusive Bus Lanes: Comprehensive Comparative
           Analysis of Urban Corridor Performance

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      Authors: Kareem Othman, Amer Shalaby, Baher Abdulhai
      Abstract: Transportation Research Record, Ahead of Print.
      Exclusive bus lane (EBL) is one of the most common transit prioritization strategies implemented to improve transit speed. However, one major drawback of implementing EBLs is the associated reduction in road capacity left for other road users. In corridors with EBLs and infrequent bus service, the lanes are underutilized for extended periods of time. Dynamic bus lane (DBL), a new priority strategy enabled by vehicle connectivity, can provide buses with priority while allowing the general traffic to access the bus lane when buses are not present. Although the DBL concept is promising, a limited number of studies have explored its effectiveness under various conditions. Thus, this paper investigates the impacts of DBLs through a comparison with EBLs and mixed traffic operation under different levels of traffic demand and transit frequency. As a case study, the Eglinton East corridor in Toronto, Canada, was simulated using Aimsun Next, and different scenarios of behavioral impacts were considered in the analysis. The results reveal that DBL is a promising strategy with potential to improve the overall corridor performance over a wide range of traffic and transit service conditions, especially under intermediate traffic demand levels. On the other hand, EBL can be an efficient prioritization strategy that improves the overall corridor performance under high traffic demand and high transit frequency levels, but only if accompanied by a major mode shift from auto to transit.
      Citation: Transportation Research Record
      PubDate: 2022-06-14T10:23:44Z
      DOI: 10.1177/03611981221099517
       
  • Using Large-Scale Drone Data to Monitor and Assess the Behavior of Freight
           Vehicles on Urban Level

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      Authors: Allister Loder, Thomas Otte, Klaus Bogenberger
      Abstract: Transportation Research Record, Ahead of Print.
      Compared with public transport operations, urban freight traffic and its associated delivery operations seem to be frequently overlooked in urban traffic management and traffic flow theory. One explanation for this is certainly the lack of available data, as the competitive freight transport market is fragmented and several actors are unwilling to collect or share tactical and operational data. In this study, we use the unique pNEUMA drone data set from Athens, Greece, to shed light on urban freight operations. We discuss macroscopic traffic indicators in a multimodal context. As the vehicle stopping behavior can adversely influence traffic flow, we reveal the stopping behavior of the different modes represented in the data set using clustering techniques. We find that urban freight vehicles’ stopping frequency lies between the stopping frequencies of cars and buses. We reveal the distribution of stopping times for loading and unloading stops in Athens to have a mean of around 380 seconds. Clustering all loading and unloading stops further reveals three groups of loading and unloading stops that could be labeled by incorporating knowledge and expertise about local particularities. The limited flight time of drones, owing to their battery capacities, did not allow reconstruction of longer vehicle routes, such as an entire vehicle tour within the network. However, this could be addressed in future research by realizing continuous large-scale monitoring routines. The revealed vehicle behavior parameters can be used in traffic models to generate further insights into the impacts of urban freight transport to inform public sector decision makers.
      Citation: Transportation Research Record
      PubDate: 2022-06-14T10:21:03Z
      DOI: 10.1177/03611981221093620
       
  • Numerical Investigation of Hydraulic Conductivity Variation on Highway
           Slopes Made of Expansive Yazoo Clay

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      Authors: Mohammad Sadik Khan, Masoud Nobahar, John Ivoke, Farshad Amini
      Abstract: Transportation Research Record, Ahead of Print.
      Expansive soils cover more than 25% of the total area of the United States and are subjected to shrink-swell behavior with moisture variation. With successive moisture and temperature variations over the seasons, the hydraulic conductivity of the expansive soil is subjected to change because of the development of shrinkage cracks which affect the vertical hydraulic conductivity, whereas the horizontal hydraulic conductivity remains negligibly constant. This affects the percolation behavior of the subgrade soil and, in turn, reduces the soil strength, as one of the major factors of slope failure. However, no study has been done on the change in the hydraulic properties of expansive soil with time and its effect on highway slopes. The current study intends to investigate the hydraulic conductivity and matric suction variation at different wet-dry cycles on highway slopes. An instantaneous profile method to investigate the changes in hydraulic conductivity during 1N to 5N wet-dry cycles was utilized. The finite element method in Plaxis was conducted to evaluate the effect of different frequencies and duration of rainfall on water intrusion, and the corresponding change in the matric suction of the highway slope. The selected rainfall pattern is evaluated at different intensities and durations of rainfall based on 100-years return periods. The flow analysis showed that the suction dropped at the highway slope with the presence of rainfall.
      Citation: Transportation Research Record
      PubDate: 2022-06-14T02:01:15Z
      DOI: 10.1177/03611981221099508
       
  • Train Operation Curve Optimization for an Urban Rail Interval With
           Multi-Parameter Adjustment

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      Authors: Lianbo Deng, Min Zhong, Jing Xu, Guangming Xu
      Abstract: Transportation Research Record, Ahead of Print.
      This paper proposes an energy consumption optimization method of train operation by controlling multiple parameters for an urban rail interval. The parameters include the maximum operation speed, the ratio of the minimum coasting speed to the maximum speed, the maximum traction, and the braking force. Based on the mass belt model, an optimization model of train operation is built with these parameters as decision variables. The objective function is to minimize the energy consumption and the penalty on the running time delays for the observed rail interval. A simulated annealing algorithm is designed to solve the model, which adopts synergic adjustment of multiple parameters based on the influence of the running time with variation of each parameter. A numerical example of Guangzhou Metro Line 8 is adopted to test the method. The results show that the maximum operation speed has a decisive influence on the optimal train operation strategy, interval running time, and energy consumption; the train traction has a direct effect on energy consumption; the train braking force has multiple optimal solutions; moreover, the energy-saving strategy has a significant effect on energy saving in a longer running time.
      Citation: Transportation Research Record
      PubDate: 2022-06-14T01:59:13Z
      DOI: 10.1177/03611981221097702
       
  • Impact of Airspace Restrictions on Urban Air Mobility Airport Shuttle
           Service Route Feasibility

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      Authors: Mark T. Kotwicz Herniczek, Brian J. German
      Abstract: Transportation Research Record, Ahead of Print.
      Initial urban air mobility (UAM) operations are anticipated to include airport shuttle services between airport terminals and city centers. UAM airport shuttle operations have the potential to improve the customer experience and provide airports with new revenue streams but risk interfering with current airport operations. In this paper, we develop a discrete, heuristics-based optimization framework to explore the impact of airspace constraints and the placement of vertiports in the airport terminal area on the feasibility of UAM shuttle operations. The framework is applied to the terminal areas of Hartsfield-Jackson Atlanta International Airport (ATL), Dallas Fort Worth International Airport (DFW), and Los Angeles International Airport (LAX). Small-scale UAM operations are found to be feasible at all three airports with current terminal-area procedures, particularly if UAM aircraft are classified as helicopters. Scaled-up operations are found to be most feasible at ATL because of the possibility of segregating UAM aircraft from commercial traffic, whereas scaled-up operations at LAX and DFW are expected to require the adoption of new technologies, procedures, and regulations.
      Citation: Transportation Research Record
      PubDate: 2022-06-14T01:56:53Z
      DOI: 10.1177/03611981221094575
       
  • Bus Scheduling of Overlapping Routes Based on the Combination of All-Stop
           and Stop-Skipping Services

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      Authors: Mingye Zhang, Min Yang, Da Lei, Xiammin Song
      Abstract: Transportation Research Record, Ahead of Print.
      Developing public transportation is an effective way to alleviate traffic congestion and reduce fossil fuel consumption. However, the result of ineffective public transport planning can be that some bus lines have long overlapping intervals, and share many common stops between them, which causes a significant waste of resources. The current bus scheduling method does not consider the imbalance of passenger flow between different stops or combine the overlapping interval with transit mixed scheduling, including all-stop and stop-skipping services. Therefore, based on the analysis of the characteristics of overlapping interval, this paper proposes a combined bus scheduling method, which includes both all-stop and stop-skipping bus services. The method is a deterministic method applied in the scheduling stage of transit planning. The method optimizes scheduling strategies by minimizing total passenger travel time, including the waiting time and the in-vehicle travel time, and the line frequency of each bus service is taken as the decision variable. Then a genetic algorithm is designed to find the optimal solution. The model is verified by two bus lines in Changchun city. The experimental results showed that the proposed model could reduce total passenger travel time by 7.71% compared with the existing scheduling method. The combined bus scheduling method can supplement the research on bus scheduling of overlapping routes and provide suggestions for operators.
      Citation: Transportation Research Record
      PubDate: 2022-06-14T01:53:08Z
      DOI: 10.1177/03611981221098392
       
  • Modeling System-Wide Urban Rail Transit Energy Consumption: A Case Study
           of Boston

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      Authors: Zhuo Han, Eric Gonzales, Eleni Christofa, Jimi Oke
      Abstract: Transportation Research Record, Ahead of Print.
      Rapid transit systems are critical components of urban public transportation networks in their impact, not only on personal mobility but also on the energy and environmental costs associated with network operations. To facilitate effective planning for current and future needs, a framework is required that provides important consumption metrics and also explains the various contributors to energy consumption, along with their interactions. To address this gap, we estimated models that utilized operational and ridership data for the Massachusetts Bay Transportation Authority’s rapid transit system, as well as ambient temperature, to accurately predict system-wide electricity consumption. The models were trained with data from 2019 and tested with data from 2020. The estimated multiple linear regression (MLR) and random forest (RF) models explained 93% and 95% of the variance in the data set, respectively. The MLR model provided predictions with a root mean squared error (RMSE) of 2.7 MWh and mean absolute percentage error (MAPE) of 4.68%, while the RF model resulted in an RMSE of 2.94 MWh and MAPE of 5.01%. We also investigated the impacts of COVID-19 on the transit system by exploring the effects on ridership, energy consumption, cost, and train movement metrics before and during the pandemic. We find that the models are robust and perform well, even with the significant disruptions associated with the COVID-19 pandemic.
      Citation: Transportation Research Record
      PubDate: 2022-06-14T01:44:29Z
      DOI: 10.1177/03611981221096442
       
  • Balanced Mix Design and Benchmarking: A Case Study in Establishing
           Performance Test Thresholds

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      Authors: Benjamin F. Bowers, Stacey D. Diefenderfer, Nathan Moore, Tiana Lynn
      Abstract: Transportation Research Record, Ahead of Print.
      A balanced mix design (BMD) approach for asphalt mixtures incorporates laboratory performance tests into the mix design acceptance process. However, test selection and subsequent performance thresholds must be selected, which is no easy endeavor when considering the number of promising tests and the variation in asphalt mix designs and components between states or regions. While the Virginia Department of Transportation’s (VDOT) BMD specification has been circulated for multiple years now, this article presents the approach taken by VDOT to investigate the various tests, considerations taken in selecting tests, and the establishment of performance thresholds. Data and discussion of six different performance tests encompassing durability, rutting, and cracking for 11 common Virginia mixes are presented. The performance threshold selection process is outlined. Further considerations in the final test selection process are discussed. In conclusion, the initial draft specification for BMD is provided.
      Citation: Transportation Research Record
      PubDate: 2022-06-14T01:42:29Z
      DOI: 10.1177/03611981221096434
       
  • Identifying High-accuracy Regions in Traffic Camera Images to Enhance the
           Estimation of Road Traffic Metrics: A Quadtree-based Method

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      Authors: Yue Lin, Ningchuan Xiao
      Abstract: Transportation Research Record, Ahead of Print.
      The growing number of real-time camera feeds in urban areas has made it possible to provide high-quality traffic data for effective transportation planning, operations, and management. However, deriving reliable traffic metrics from these camera feeds has been a challenge because of the limitations of current vehicle detection techniques, as well as the various camera conditions, such as height and resolution. In this work, a quadtree-based algorithm is developed to continuously partition the image extent until only regions with high detection accuracy remain. These regions are referred to as high-accuracy identification regions (HAIRs) in this paper. We demonstrate how the use of HAIRs can improve the accuracy of traffic density estimates using images from traffic cameras at different heights and resolutions in Central Ohio. Our experiments show that the proposed algorithm can be used to derive robust HAIRs in which vehicle detection accuracy is 41% higher than that in the original image extent. The use of HAIRs also significantly improves the traffic density estimation with an overall decrease of 49% in root mean squared error.
      Citation: Transportation Research Record
      PubDate: 2022-06-14T01:39:44Z
      DOI: 10.1177/03611981221096117
       
  • Short Duration Crash Prediction for Rural Two-Lane Roadways: Applying
           Explainable Artificial Intelligence

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      Authors: Zihang Wei, Subasish Das, Yunlong Zhang
      Abstract: Transportation Research Record, Ahead of Print.
      Conventional traffic crash analysis methods often use highly aggregated data, making it difficult to understand the effects of time-varying factors on crash occurrence. In this study, the combined effect of roadway geometry, speed distribution, and weather conditions on crash occurrence and severity was investigated on short duration daily level crash data. This study collected data from four different sources on rural two-lane roadways in Texas. A machine learning method, XGBoost (eXtreme Gradient Boosting), was applied to train the data. To mitigate imbalanced data problems, a synthetic minority oversampling technique (SMOTE) was applied. The XGBoost model was trained separately on all crash occurrences and severe crash occurrences. Finally, an explainable artificial intelligence (AI) technique, SHAP (SHapley Additive exPlanation), was applied to investigate the contribution of all variables to the model’s output. The results show that annual average daily traffic has a significant impact on all crash occurrences and severe crash (fatal and incapacitating injury) occurrences on rural two-lane roadways. Moreover, weather condition factors including daily precipitation, average visibility, and the standard deviation of visibility show association with high crash occurrences. The short duration crash prediction models of this study can provide more insights into the relationships between crash, geometric variables, traffic exposure, weather, and operating speed.
      Citation: Transportation Research Record
      PubDate: 2022-06-14T01:37:44Z
      DOI: 10.1177/03611981221096113
       
  • Benefit–Cost-Based Method to Determine When Safety Performance Functions
           Should be Redeveloped for Use in Intersection Network Screening

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      Authors: Mohammad Zarei, Bruce Hellinga, Pedram Izadpanah
      Abstract: Transportation Research Record, Ahead of Print.
      Network screening is the process of identifying the sites within the road network that are of highest priority for detailed safety audits and interventions. Contemporary road safety network screening methods rely on safety performance functions (SPFs), which are statistical models relating site characteristics to the number of crashes. SPFs are developed on the basis of historical crash and traffic volume data and should be periodically redeveloped to accurately reflect changes in the underlying relationships that result from changes in the network, traffic behavior, operational performance of vehicles, rules of the road, and other contributing factors. However, presently, there is no guidance available to practitioners to enable them to objectively decide when redevelopment of SPFs is warranted. In this study, we present a practical method to provide this guidance for network screening of intersections that reflects both the expected benefits of SPF redevelopment in relation to improved network screening accuracy and the cost of redevelopment. The data required for this method are either already available in municipalities which have locally developed SPFs or can be easily estimated. The estimation models for the method are created based on real data sets and were successfully tested on validation data sets.
      Citation: Transportation Research Record
      PubDate: 2022-06-13T12:42:26Z
      DOI: 10.1177/03611981221092403
       
  • Macro Analysis to Estimate Electric Vehicles Fast-Charging Infrastructure
           Requirements in Small Urban Areas

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      Authors: Harprinderjot Singh, Mohammadreza Kavianipour, Amirali Soltanpour, Fatemeh Fakhrmoosavi, Mehrnaz Ghamami, Ali Zockaie, Robert Jackson
      Abstract: Transportation Research Record, Ahead of Print.
      Electric vehicles (EVs) are known to reduce emissions and fossil fuel dependency. However, the limited range, long charging time, and inadequate charging infrastructure have hampered the adoption of EVs. The current EV charging infrastructure planning studies and tools require detailed information, extensive resources, and skills that can be a significant barrier to urban areas for finding the required charging infrastructure to support a targeted EV market share. This study generates regression models to estimate the number of direct current fast charging stations and the chargers to support the EV charging demand for urban areas. These models provide macro-level estimates of the required infrastructure investment in urban areas, which can be easily implemented by policy-makers and city planners. This study incorporates data obtained from applying a disaggregate optimization-based charger placement model, developed recently by the same authors, for multiple case studies to generate the required data to calibrate the macro-level models, in the state of Michigan. This simulated data set includes the number of charging stations and chargers for each market share, technology advancement scenario, and the transportation network topology. The results show that the number of charging stations reduces with battery size and charging power and increases with EV market share and the road network lane length. The number of chargers reduces with charging power, whereas it increases with battery size, EV market share, and vehicle miles traveled in the system. The model developed here can be applied to any state having urban characteristics and weather conditions similar to Michigan.
      Citation: Transportation Research Record
      PubDate: 2022-06-11T10:32:09Z
      DOI: 10.1177/03611981221093625
       
  • Roadmap for Child-Pedestrian Training Program Informed by Contextual Crash
           Data

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      Authors: Anika Jannat Rimu, Shuchisnigdha Deb, Mouyid Islam, Roya Etminani-Ghasrodashti, Anurag Pande
      Abstract: Transportation Research Record, Ahead of Print.
      Vulnerable road users (VRUs, i.e., pedestrians and bicyclists) have seen an alarming rise in fatalities in recent years. School-age pedestrians in lower-income neighborhoods may be particularly at risk. This paper proposes a data-driven safe-systems approach to develop safety countermeasures for areas near elementary schools serving disadvantaged populations. A review of past literature on child-pedestrian training programs confirms that videos, lectures, and website-based training can provide children with vital information to improve their cognitive abilities relevant to walking safely. However, to improve pedestrian behavior on the road, children need to be safely exposed to traffic environments and practice interactions with traffic. Therefore, the use of virtual reality (VR) is recommended as a platform to introduce children to traffic interactions. Furthermore, the review of existing child-pedestrian training programs showed that most existing training programs (VR-based or otherwise) have an ad-hoc selection of roadway and traffic environment scenarios. Moreover, none of the training programs are designed to address safety issues faced by children in low-income neighborhoods specifically. To address these issues, this study gathered and analyzed crash data for VRUs around schools located in two metropolitan areas: Dallas County in TX and Tampa Bay in FL. Analysis of crash data identified the most prominent factors leading to most crashes as well as disproportionately more severe crashes. A VR-based child-pedestrian training program that involves children interacting with designed environments grounded in local crash data from disadvantaged areas is recommended for a more effective and equitable training platform.
      Citation: Transportation Research Record
      PubDate: 2022-06-11T10:27:43Z
      DOI: 10.1177/03611981221092386
       
  • How Should Vehicle Miles Traveled Displaced by E-Scooter Trips be
           Calculated'

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      Authors: Dominique Meroux, Andrea Broaddus, Cassandra Telenko, Hui Wen Chan
      Abstract: Transportation Research Record, Ahead of Print.
      A dominant practice in assessing mode shift for scooter sharing is to survey scooter riders on what transportation mode they otherwise would have taken. Trip share displacing car modes and average scooter trip distance are common metrics used to support calculations like vehicle miles traveled (VMT) and emissions reductions. This practice assumes a 1:1 relationship between trip and mile replacement, implying no relationship between mode replaced and scooter trip distance. In our study, we test this assumption. An in-app end of trip survey was answered by nearly 12,000 e-scooter riders using Spin e-scooter sharing in four U.S. cities: San Francisco, Tampa, Washington D.C., and Portland. Trip GPS breadcrumb distance was linked to survey responses, enabling scooter distance traveled to be calculated by mode displaced. We calculate scooter distance share and average trip distance conditional on mode displaced for scooter trips that displaced personal car, taxi, and transportation network company trips as alternative metrics to trip share and average trip distance, respectively. To account for the effects of built environment, we cluster scooter trips on the U.S. Environmental Protection Agency National Walkability Index for trip start location. We find that across cities and walkability index clusters, the conventional trip share and average trip distance metrics consistently overestimate walk-mode shift and underestimate car VMT displacement by e-scooter use. To ensure an accurate representation of mode shift, we recommend that cities, operators, and researchers report average trip distance conditional on mode displaced or scooter distance share. The mode shift observed across the four cities in this study, for example, revealed that about one-third of the distance travelled by scooters displaced car VMT.
      Citation: Transportation Research Record
      PubDate: 2022-06-10T09:45:39Z
      DOI: 10.1177/03611981221099506
       
  • Comparison of Ballast Drainage Improvement Between Track Lifting and
           Shoulder Cleaning Based on CFD Simulations

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      Authors: Yufeng Gong, Yu Qian, Xiaobin Chen
      Abstract: Transportation Research Record, Ahead of Print.
      Railroad track performance largely depends on ballast drainage conditions. Over the years, different ballast maintenance methods have been developed and applied in the field, aiming to restore ballast drainage capability. But the benefits from different maintenance methods have not been well quantified and compared. This study investigates and compares the benefits of the two popular ballast drainage maintenance methods used in North America, shoulder cleaning and track lifting, through numerical simulations based on computational fluid dynamics (CFD). Different fouling conditions are simulated with permeabilities quantified from the field-collected fouled ballast samples to ensure that the numerical models are representative. Because the unit cost of shoulder cleaning and track lifting varies and depends on the specific application conditions, the normalized drainage health index (NDHI) and the normalized drainage restoration ratio (NDRR) are introduced to make fair comparisons and provide unbiased parameters for practitioners to use in the future. Preliminary results from this study indicate shoulder cleaning provides better ballast drainage improvement than track lifting if the unit costs per ballast volume of shoulder cleaning and track lifting are identical.
      Citation: Transportation Research Record
      PubDate: 2022-06-10T09:43:17Z
      DOI: 10.1177/03611981221098659
       
  • Developing a Cost-Effective Assessment Method for Noise Impacts at
           Non-Towered Airports: A Case Study at Purdue University

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      Authors: Chuyang Yang, John H Mott
      Abstract: Transportation Research Record, Ahead of Print.
      Aircraft noise is considered as one of the environmental impacts that most adversely affects airport development. Aircraft noise estimation tools such as the Aviation Environmental Design Tool (AEDT) are widely used by airports to mitigate local concerns for airport development. Aircraft operations and fleet mix information play important roles in aircraft performance modeling for noise prediction. However, such information is difficult to obtain at almost 85% of the 3,348 National Plan of Integrated Airport Systems (NPIAS) airports, which lack full-time air traffic control facilities and personnel. Given the increasing percentage of equipped automatic dependent surveillance-broadcast (ADS-B) aircraft in the U.S. national airspace, this paper presents a cost-effective noise estimation approach for non-towered general aviation (GA) airports. Instead of deploying physical sound meters or relying on the local air traffic control facilities, the authors collected aircraft positional data and fleet mix information based on ADS-B broadcasts. Advanced aircraft performance model parameters are constructed using four-dimensional aircraft position and a kinematic point-mass model. Aircraft-specific noise levels are interpolated based on the EUROCONTROL Aircraft Noise and Performance (ANP) database. To obtain the final noise level, two adjustments are applied to the interpolated noise values. The test results show the proposed approach can help non-towered airports predict the noise impact on any selected locations near the airport cost-effectively. Recommendations and opportunities for future investigation are also included.
      Citation: Transportation Research Record
      PubDate: 2022-06-10T09:40:35Z
      DOI: 10.1177/03611981221097705
       
  • New Equity Inputs to Prioritize Bikeshare Infrastructure Allocation:
           Learning From the COVID-19 Period

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      Authors: Joshua H. Davidson, Stephanie J. Nam, Shriya Karam, Fatima K. Koroma, Ellie M. Kim, Megan S. Ryerson
      Abstract: Transportation Research Record, Ahead of Print.
      From “pop-up” road closures to decreased transit frequencies, the COVID-19 pandemic has changed the overall supply of transport options. Even in the absence of a change in bikeshare supply, the pandemic provides a “natural experiment” under which we can assess changes in bikeshare use across diverse communities in response to transportation system changes. The pandemic offers a unique moment to particularly measure changes in use for low socioeconomic status (SES) populations as historically limited deployments of bikeshare in low-income neighborhoods limit evaluation of key metrics for this population. For low SES users to realize greater accessibility through bikeshare, they may need to take relatively longer trips, given the sparse nature of the network in low-income areas and the existing inequitable geography of opportunities in urban environments in the United States. As such, we measure the effect of the COVID-19 pandemic on average daily bikeshare trip durations in Philadelphia, PA—the major city with the highest poverty rate in the United States. Through an interrupted time series approach, we find that the effect of the pandemic on trip duration for all bikeshare users is substantial (approximately 7–12 min increase), positive, and similar across diverse geographic areas. Importantly, these findings are persistent and statistically significant even when fitting models only on data from predominantly low SES areas of Philadelphia. This change pattern suggests first that low SES users exhibit roughly equal propensity as the general population to take longer trips, and second that bikeshare can provide a resilient, equitable travel mode.
      Citation: Transportation Research Record
      PubDate: 2022-06-10T09:38:51Z
      DOI: 10.1177/03611981221098390
       
  • OD-Based Partition Technique to Improve Arterial Signal Coordination Using
           Connected Vehicle Data

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      Authors: Jianyuan Xu, Zong Tian
      Abstract: Transportation Research Record, Ahead of Print.
      Maximizing two-way arterial bands often plays a critical role in signal coordination along urban arterials. With an increasing number of signals involved, the arterial bands tend to shrink to some extent resulting in inefficient arterial signal coordination, and not all vehicles fully take advantage of the arterial bands to travel through the entire corridor. In response to that, system partition is a technique for handling arterials with many signals. Rather than designing end-to-end signal coordination, efficient arterial signal coordination is highly reliant on traffic origin and destination (OD) patterns on the arterial, which have been difficult to obtain using conventional data collection methods. The emerging big data sources, such as connected vehicles, provide great potential to gather such invaluable OD information for improving arterial signal coordination. This research proposes an easy-to-implement OD-based partition technique to improve arterial signal coordination by utilizing vehicle trajectory data automatically collected from connected vehicles. The proposed signal timing technique was tested using an arterial with 17 signalized intersections in Orange County, California. The results demonstrated that the OD-based partition technique improved the arterial average travel speed by 2.7% and 12.1% for the eastbound and westbound directions, respectively. At the same time, the proposed technique shortened the arterial average travel time by 2.6% and 11.1% for the eastbound and westbound directions, respectively. The total travel time was shortened both for the main-street and side-street major traffic flows.
      Citation: Transportation Research Record
      PubDate: 2022-06-10T09:34:26Z
      DOI: 10.1177/03611981221098692
       
  • Drainability and Clogging Behavior of Open-Graded Asphalt Friction Courses
           with Basic Oxygen Furnace Steel Slag Aggregates

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      Authors: Santanu Pathak, Rajan Choudhary, Abhinay Kumar
      Abstract: Transportation Research Record, Ahead of Print.
      Drainability of an open-graded asphalt friction course (OGAFC) is a primary functional requirement, which mainly depends on the presence of a network of interconnected air voids. These mixtures, however, are prone to clogging, which severely limits their drainability. Clogging predominantly occurs as a result of the deposition of external (sand, debris, and dust) and internal (stripped-off bitumen) materials into the pores of OGAFC, which is referred to as particle-related clogging. Another type of clogging is deformation-related clogging and it is observed mainly because of rutting along the wheel path. In this study, the drainability and clogging behavior of OGAFC mixes with basic oxygen furnace (BOF) steel slag as replacement of natural aggregates was studied. BOF steel slag was used as 0% (control mix), 25%, 50%, 75%, and 100% substitution for coarse natural aggregates in the preparation of OGAFC mixes with two types of modified binders. Three different clogging mechanisms: particle-related clogging (caused by intrusion of foreign material such as sand); stripping-related clogging (caused by the deposition of stripped-off bitumen-fines mortar), and deformation-related clogging (reduced drainability caused by permanent deformation) were considered in this study. Comparisons were made to investigate the effect of BOF steel slag on the clogging potential of OGAFC mixes. OGAFC specimens were evaluated for their drainage potential using a flexible-wall falling-head permeameter both before and after being subjected to various clogging environments. BOF-steel-slag-incorporated OGAFC mixes exhibited lower clogging potential and reported better performance in resisting clogging resulting from stripping and permanent deformation.
      Citation: Transportation Research Record
      PubDate: 2022-06-09T11:31:09Z
      DOI: 10.1177/03611981221095525
       
  • Identifying Important Ports in Maritime Silk Road Shipping Network from
           Local and Global Perspective

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      Authors: Yanbin Yang, Wei Liu, Xu Xu
      Abstract: Transportation Research Record, Ahead of Print.
      Some key ports exist in the Maritime Silk Road shipping network that have a high impact on the whole of maritime transportation. An efficient identification of these crucial ports is of great importance, to alleviate the spread of port congestion, control shipping delays, and improve transportation efficiency. This paper proposes a novel method to identify the key ports by comprehensively considering local propagation and global centrality (LPGC), based on the complex network theory. Taking the ports along the Maritime Silk Road shipping network as an example, the Susceptible–Infected–Susceptible (SIS) model and Kendall’s correlation coefficient are compared with several centrality measures to evaluate the feasibility and efficiency of the LPGC method. The obtained results demonstrate that, compared with the existing methods, the proposed method has higher accuracy and can more accurately identify the influential ports. Finally, the obtained port importance ranking also provides a theoretical basis for the selection of ports that should give a priority to maintaining or ensuring their service capacity in practice.
      Citation: Transportation Research Record
      PubDate: 2022-06-09T11:17:46Z
      DOI: 10.1177/03611981221097704
       
  • An optimization Model Combining Operator-Based Relocation With User-Based
           Relocation for Electric Carsharing Systems

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      Authors: Ning Wang, Yan Duan, Shengling Jia
      Abstract: Transportation Research Record, Ahead of Print.
      This paper proposes an optimization model combining operator-based relocation with user-based relocation for electric carsharing systems, aiming to improve the low usage of vehicles and the imbalance between supply and demand. First, the back-propagation neural network prediction model of vehicle quantity demand and the distribution fitting model of energy demand are constructed. In the operator-based scheme, optimization models of inter-regional and intra-regional relocation are constructed. In the user-based scheme, a multi-objective optimization model considering the operator profit and user experience is proposed. Taking the actual operation data of an electric carsharing company in Shanghai as an example, the mixed scheduling strategy of operator-based relocation and user-based relocation is validated. Results show that: (i) users are very sensitive to price changes, and station distance and price incentive will change users’ pickup and return behavior; (ii) compared with systems without vehicle relocation, the mixed scheduling strategy can reduce the using failure rate by 6.68% and increase net profit by 42.6% in the best situation; and (iii) the using-failure rate alert line, as a switching mechanism between user-based and operator-based relocation, can play a regulatory role, and with the loosening of the alert line, the frequency of operator-based relocation intervention increases, and the using-failure rate decreases further.
      Citation: Transportation Research Record
      PubDate: 2022-06-09T11:05:16Z
      DOI: 10.1177/03611981221097963
       
  • Leveraging Fully Actuated Signal Coordination and Phase Reservice to
           Facilitate Signal Timing Practices

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      Authors: Aobo Wang, Zong Tian
      Abstract: Transportation Research Record, Ahead of Print.
      Signal coordination has been deemed an effective means of improving arterial traffic operations; however, it may cause signal controllers to dwell in coordinated phases regardless of actual traffic demand, resulting in increased delay and unfavorable waiting for the minor-movement traffic. This paper proposes a strategy to facilitate such signal timing practices by actuating the coordinated phase, known as fully actuated coordination, and enabling phase reservice. The actuated coordinated phase can terminate early in response to traffic actuations with minimal influence on arterial progression, and phase reservice allows for a flexible order of phase service, which can lead to an effective re-allocation of the remaining green time after the coordinated phase gaps out. The proposed improvements focus on the situation where traffic volume is low to moderate whereas the coordination cycle length has to be relatively long, such as applying signal coordination at a minor intersection or during the late-night period (e.g., between 9 p.m. and 5 a.m.). The performance of the proposed strategy is explored through hardware-in-the-loop simulation. The simulation results indicate that, as compared with conventional signal coordination, the proposed strategy can achieve a reduction in the overall delay on the non-coordinated movements while the number of stops along the arterial would not significantly increase. Other benefits can also be observed in simulation, for example, speeding control during the late-night period. In addition, the determination of the non-actuated portion of the coordinated phase is studied.
      Citation: Transportation Research Record
      PubDate: 2022-06-09T11:01:56Z
      DOI: 10.1177/03611981221098673
       
  • Transit and Active Transportation Use for Non-Commute Travel Among
           Portland Transit-Oriented Development Residents

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      Authors: Jennifer Dill, Nathan McNeil
      Abstract: Transportation Research Record, Ahead of Print.
      Transit-oriented development (TOD) seeks to promote non-single occupancy vehicle travel by placing dense residential and mixed-use buildings near high-capacity, high-frequency transit. Most research to date on the impact of TODs on travel behavior has focused on commute trips; however, many trips are for non-work purposes, and a sizable portion of the population does not commute to work. This study utilizes a set of surveys, conducted between 2005 and 2019 in the Portland OR region to assess factors associated with whether or not, and how often, TOD residents walk, bike, or take transit for home-based non-work trips. Findings show that about 20% of TOD residents take transit for non-work trips at least once per week, while 65% walk or bike for such trips. Attitudes and housing preferences are important factors in predicting whether and how frequently TOD residents walk, bicycle, or take transit for non-work trips. TOD residents make more non-work trips on transit when there is better transit access, and they walk and bicycle for more of these trips when street connectivity is higher. Lower access to a personal vehicle is also an important factor in non-work travel.
      Citation: Transportation Research Record
      PubDate: 2022-06-09T10:58:54Z
      DOI: 10.1177/03611981221098391
       
  • Visual Map-Based Localization for Intelligent Vehicles Using Around View
           Monitoring in Underground Parking Lots

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      Authors: Zhe Zhou, Zhaozheng Hu, Hanbiao Xiao, Qianwen Tao
      Abstract: Transportation Research Record, Ahead of Print.
      Accurate and robust self-localization is a crucial task for intelligent vehicles. Because of limited access to GPS signals, localization in underground parking lots remains a problem. In this paper, fusion localization for intelligent vehicles using the widely available around view monitoring (AVM) is conducted by Kalman filter based on second-order Markov motion model (KF-MM2). The proposed method consists of two steps, one for visual map construction from AVM images and the other for map-based multi-scale localization. The proposed visual map consists of a series of nodes. Each node encodes both holistic and local visual features computed from AVM images, three-dimensional structure, and vehicle pose. In the localization step, the process of image-level localization is modeled as a Hidden Markov Model (HMM), in which the map nodes are hidden states. The result of image-level localization is calculated using forward algorithm by the given AVM image sequence. Then the metric localization is computed from local features matching. Finally, the metric localization is fused with the prediction by KF-MM2. The proposed method has been verified in two typical underground parking lots. Experimental results demonstrate that the proposed method can achieve an average error of 0.39 m in underground parking lots.
      Citation: Transportation Research Record
      PubDate: 2022-06-09T10:55:14Z
      DOI: 10.1177/03611981221094585
       
  • Innovative Method for Estimating Large Truck Volume Using Aggregate Volume
           and Occupancy Data Incorporating Empirical Knowledge Into Linear
           Programming

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      Authors: Yangsong Gu, Diyi Liu, John Stanford, Lee D. Han
      Abstract: Transportation Research Record, Ahead of Print.
      Monitoring large trucks (LT) plays an essential role in the operation and planning of transportation and economics. Although many “advanced” traffic detectors (e.g., infrared, microwave, and magnetic sensors) can identify LT, those technologies are not as widely deployed as loop detectors, and their performance is disputed. While many previous studies have investigated estimation of truck traffic using gross volume and occupancy information from loop detectors, most of them are based on mean effective vehicle length (MEVL), and thereby vulnerable to dynamic traffic conditions and dependence on exogenous data sources. This paper aims to develop an original method of estimating LT volume using detector output (i.e., volume and occupancy). A linear optimization problem is formulated by minimizing the difference between observed occupancy and theoretical “best guess.” LT and short vehicle (SV) lengths and their counts are devised as decision variables to compensate for variations in speed and length. To assess the proposed method, volume and occupancy data output in 30 s granularity from three different cases are prepared: microscopic simulation, Tennessee Radar Detector System (TN-RDS), and California Freeway Performance Measures System (PeMS). For the simulation, 12 different scenarios were built up and the results indicate that the mean absolute error of LT estimates increases with traffic volume and truck penetration. In two real-world cases, the LT estimates are close to ground truth from video and weigh-in-motion (WIM) station records. Furthermore, this simple and online LT volume estimate approach can be extended to other stations and to monitor a wide range of LT activities.
      Citation: Transportation Research Record
      PubDate: 2022-06-09T10:51:54Z
      DOI: 10.1177/03611981221094569
       
  • Impacts of Lightweight Aggregate Interlayers for Air Convection Embankment
           on Pavement Thermal Profile and Pavement Performance in Alaskan Permafrost
           Regions

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      Authors: Hanli Wu, Yizhuang David Wang, Xiong Zhang, Jenny Liu
      Abstract: Transportation Research Record, Ahead of Print.
      Crushed-rock air convection embankment (ACE) has been used to mitigate pavement distresses caused by climatic extremes in permafrost regions for more than three decades. This study proposes using lightweight aggregates as cost-effective alternative materials to overcome the shortage of desired crushed rocks needed for ACE in interior Alaska. This paper presents an investigation of the performance of six selected pavement structures: an asphalt pavement typical of the northern region of Alaska and five pavements reinforced with different paving interlayers (i.e., silty sand/gravel, crushed rocks, cellular concrete aggregate, foam glass aggregate, and lightweight expanded clay aggregate). Pavement thermal analyses using Temperature Estimate Model for Pavement Structures (TEMPS) program and ANSYS Fluent software were performed to predict heat transfer patterns and thermal performance for each case. Pavement performance analyses using viscoelastic-based FlexPAVE™ and the elastic-based Alaska Flexible Pavement Design (AKFPD) program were conducted to evaluate the long-term performance and structural stability of subgrade soil with different types of interlayers. The results showed that the lightweight aggregate ACEs improved cooling performance more effectively than the crushed-rock ACE. The lightweight aggregate interlayers could maintain desired thermal insulation in summer and enhance the cooling effect in winter. The modeling results identified the high potential of using lightweight aggregates as alternative ACE materials to improve pavement service life and subgrade stability.
      Citation: Transportation Research Record
      PubDate: 2022-06-09T10:49:11Z
      DOI: 10.1177/03611981221097401
       
  • Impact of COVID-19 on Texas Rural Transit Districts with Emphasis on their
           Older Adult Riders

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      Authors: Mark Dinhobl, Sarah Fasanando, Rebekka Dudensing, James Mjelde
      Abstract: Transportation Research Record, Ahead of Print.
      The COVID-19 pandemic presented rural transit districts (RTDs) challenges in providing services to riders, but also led to opportunities. This study’s objectives are to gain insight on the effect of COVID-19 on older adult RTD ridership, and gain an understanding of how RTDs were affected by and are adapting to the health crisis. Leaders from 30 of the 36 Texas RTDs completed an online questionnaire with 26 agreeing to participate in a semi-structured interview concerning the impact of COVID-19 on their district. Few differences are found between the responses of RTDs. RTDs followed recommended guidelines and implemented heightened cleaning standards that most leaders felt will likely remain in place for the future. Main information sources for responding to the pandemic were local health officials, the Center for Disease Control and Prevention, and other transit districts. Most RTDs projected a financial loss because of the pandemic but received additional funding to help cope with the pandemic. RTDs believe their older adults may be suffering from social isolation but older adults are appreciative of their efforts. Many RTDs developed contactless payment methods, although they were divided on the future role of new technologies. Incorporating RTDs into disaster and pandemic planning increases rural areas’ resiliency and ability to respond to disasters and pandemics lessening the effect of these events on rural populations and communities.
      Citation: Transportation Research Record
      PubDate: 2022-06-09T10:23:31Z
      DOI: 10.1177/03611981221097400
       
  • Station-Level Effects of the COVID-19 Pandemic on Subway Ridership in the
           Seoul Metropolitan Area

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      Authors: Myung-Jin Jun, Mi-Young Yun
      Abstract: Transportation Research Record, Ahead of Print.
      This paper investigates the station-level impacts of the coronavirus disease (COVID-19) pandemic on subway ridership in the Seoul Metropolitan Area. Spatial econometric models are constructed to examine the association between ridership reduction caused by the pandemic and station-level characteristics during the pandemic years 2020 and 2021. The results reveal unequal effects on station-level ridership, based on the pandemic waves, the demographics, and the economic features of pedestrian catchment areas. First, the subway system was severely disrupted by the pandemic, with significant decreases in ridership—by about 27% for each of the pandemic years—compared with the pre-pandemic year (2019). Second, the ridership reduction was sensitive to the three waves in 2020 and responded accordingly; however, it became less sensitive to the waves in 2021, indicating that subway usage was less responsive to pandemic waves during the second year of the pandemic. Third, pedestrian catchment areas with higher numbers of younger residents (in their 20s) and older residents (65 years and older), those with more businesses requiring face-to-face interactions with consumers, and stations located in the employment centers were hit the hardest in ridership reduction caused by the pandemic.
      Citation: Transportation Research Record
      PubDate: 2022-06-09T10:19:55Z
      DOI: 10.1177/03611981221096665
       
  • Concurrent Optimization of Cycle Length, Green Splits, and Offsets for the
           Diverging Diamond Interchange

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      Authors: Dawson Do, Yen-Yu Chen, Gang-Len Chang
      Abstract: Transportation Research Record, Ahead of Print.
      Diverging diamond interchange (DDI) has received increased attention from the traffic community for its efficiency in reducing delays for vehicles at on- and off-ramps. The conflicting through movements between a DDI’s two crossover intersections mean that its signal plan must concurrently consider the progression for all critical paths to ensure overall efficiency. In light of DDI’s unique geometric features, the design of its signal plans typically starts with the cycle length and green splits for its two crossover intersections, and then employs available progression models to produce the optimal offsets for those critical paths. Such a two-stage design methodology, however, often cannot yield system-wide optimal results because the optimal progression bandwidth and signal settings are interdependent. Moreover, inefficient coordination between its two crossover intersections may cause excessive queues on the DDI’s bridge segment. This paper therefore presents a mixed-integer linear programming (MILP) model that can concurrently optimize the cycle length, green splits, and offsets for a DDI’s two crossover intersections under the given traffic patterns and geometric constraints such as the link length. The results of extensive numerical analyses with a real-world DDI have confirmed the effectiveness of the proposed model and its robustness in response to demand fluctuation.
      Citation: Transportation Research Record
      PubDate: 2022-06-08T09:59:13Z
      DOI: 10.1177/03611981221096664
       
  • Accessibility-Based Location of International Multimodal Logistics Hubs: A
           Case in China

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      Authors: Xinfang Zhang, Chengliang Liu, Yan Peng
      Abstract: Transportation Research Record, Ahead of Print.
      This paper presents an approach to address the problem of location of international multimodal logistics hubs (IMLHs) in the international multimodal network from the perspective of accessibility. The approach has three phases: constructing multiple accessibility indices, identifying the candidate IMLHs, and determining the optimal IMLHs. First, seven accessibility indices are constructed considering multiple transport segments and modes in the international transportation chain. Second, several candidate IMLHs are identified according to the integrated accessibility calculated by a modified GRA-TOPSIS (grey relational analysis technique for order preference by similarity to ideal solution). Third, an accessibility-based gravity p-median model is established to determine optimal IMLHs. Finally, the approach is applied to IMLHs in China. The results show that the distribution of the identified 28 candidate IMLHs is reasonable, and the 15 optimal IMLHs can serve most of the cargo origins in China. The study provides support for decision-makers in the location of multimodal transportation hubs.
      Citation: Transportation Research Record
      PubDate: 2022-06-08T09:52:29Z
      DOI: 10.1177/03611981221096440
       
  • Subarea Partition Based on Correlation Analysis with Edge-Elimination
           Strategy Using Automatic License Plate Recognition Data

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      Authors: Siping Ke, Wei Liu, Zhenbo Lu, Wenming Rao, Chengchuan An, Jingxin Xia
      Abstract: Transportation Research Record, Ahead of Print.
      To partition an urban network into several subareas (i.e., subarea partition) is a vital step for regional coordinated signal control. The correlation between intersections must be analyzed for achieving reliable subarea partition results. However, because of the incompleteness of spatial–temporal information in traffic data, previous studies merely explored the relationship between any intersections. Subarea partition considering the correlation of any pair of intersections remains a challenge in a large-scale network. This paper proposes a subarea partition method that integrates a novel correlation-degree model and the Newman fast algorithm with an edge-elimination strategy using automatic license plate recognition (ALPR) data. First, vehicle trips are extracted and a correlation-degree model is developed for measuring the relationship of any pair of intersections. Second, an edge-elimination strategy is proposed to generate candidate subarea partition solutions under conditions with different proportions of correlated edges. Finally, an optimal solution of subarea partition is identified by the ratios of ideal connected intersections to total intersections of different partition solutions’ correlation index (CI). The proposed method was implemented in a real-world urban network in Kunshan, China. The results show that the optimal partition solution can be obtained when the top 33% of correlated edges are maintained, and the ratio of ideal connected intersections’ CI is 72.35% with most of the intersections being connected, which demonstrates the rationality of the proposed partition method in large-scale urban networks.
      Citation: Transportation Research Record
      PubDate: 2022-06-08T09:49:47Z
      DOI: 10.1177/03611981221096439
       
  • Investigating Spatial Correlations Between Land Use and Pedestrian Injury
           Severity in Crashes Occurring Away From Intersections in Northwest Florida
           

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      Authors: Mohammadreza Koloushani, Alican Karaer, Eren Erman Ozguven, Thobias Sando, Maxim A. Dulebenets, Ren Moses
      Abstract: Transportation Research Record, Ahead of Print.
      Roadway crashes are an increasing concern worldwide, and pedestrians are among the most vulnerable road users because of several special characteristics, including their fragility. While focusing on pedestrian-involved crashes that occurred far away from intersections, a more systematic investigation is needed to determine whether there is a relationship between the severity of these crashes and the land use types surrounding the crash locations. To investigate this issue, a network-based logistic regression model was employed to assess the impact of the distance between pedestrian-involved crash locations and the centroid of an associated land use of various types. In addition, a set of logistic models was developed to assess the effect of traffic- and environment-related factors, such as daylight and the average annual daily traffic (AADT), on the severity of crashes occurring around each land use. Several types of land use appeared to be influential in predicting pedestrian-involved crash severity. The probability of a severe pedestrian-involved crash increased around commercial land use types including retail stores or night clubs whereas it decreased around university campuses. Moreover, among the crash attributes, daylight contributed to the severity of pedestrian-involved crashes regardless of the surrounding land use type while average traffic was found to be a statistically significant factor for the crashes that occurred particularly around parking lots and office buildings. Pedestrian-involved crashes mostly occurred in the vicinity of office buildings during daylight hours, and the pedestrians were less likely to be severely injured. The findings provided valuable insight into the measurements concerning pedestrian safety with respect to various types of land use.
      Citation: Transportation Research Record
      PubDate: 2022-06-08T09:48:42Z
      DOI: 10.1177/03611981221096433
       
  • Walking the Last Mile: Barriers and Solutions to Suburban Transit Access

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      Authors: Lindsay M. Braun, Jesus M. Barajas, Bumsoo Lee, Rebecca Martin
      Abstract: Transportation Research Record, Ahead of Print.
      Pedestrian infrastructure plays a critical role in facilitating first-/last-mile access to transit. Efforts to connect pedestrians to transit through infrastructure improvements, however, often face considerable implementation barriers. These barriers can be particularly pronounced for suburban transit providers, which serve low-density, automobile-oriented development and often must coordinate across many jurisdictions. In this analysis, we examine strategies that transit agencies, metropolitan planning organizations, and municipalities use to build pedestrian infrastructure near suburban transit services in the United States, and the barriers they face in this process. We use Pace Suburban Bus, a transit provider in the Chicago, Illinois region, as an illustrative case study, conducting surveys with planners and interviews with diverse stakeholder groups in the agency’s service area. To complement these findings, we conduct an online survey of similar agency types in ten peer regions across the United States. The results suggest that agencies support pedestrian access to transit through a variety of plans, policies, programs, and partnerships. However, agencies face significant implementation barriers, including limited funding, competing investment priorities, jurisdictional/coordination issues, automobile-oriented planning and development, regulatory compliance issues, and limited staff capacity. Based on these findings, we propose recommendations related to planning (e.g., better inclusion/documentation of pedestrian needs in plans), policy (e.g., regional support for Complete Streets and Americans with Disability Act related policy efforts), funding (e.g., regional platforms for sharing funding opportunities), and education (e.g., staff training and community awareness campaigns). These recommendations provide specific actions that agencies at multiple levels of government can take to better support pedestrian access to transit in suburban communities.
      Citation: Transportation Research Record
      PubDate: 2022-06-08T09:45:05Z
      DOI: 10.1177/03611981221095748
       
  • Microsimulation Study Evaluating the Benefits of Cyclic and Non-Cyclic
           Max-Pressure Control of Signalized Intersections

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      Authors: Jake Robbennolt, Rongsheng Chen, Michael Levin
      Abstract: Transportation Research Record, Ahead of Print.
      Max-pressure control is a decentralized method of traffic intersection control, making computations at individual intersections simple. In addition, this method of control has been proven to maximize network throughput if any traffic signal control can stabilize the demand. This paper tests max-pressure controllers in a large-scale microsimulation of the downtown Austin network using the microscopic traffic simulation package SUMO. Nine combinations of weight function and method of defining green time are studied to see how different variations on the max-pressure controller compare. It is shown that the way green time is assigned (cyclic or non-cyclic) has a larger impact on performance than the weight function used by the max-pressure controller. Based on these results a new way of assigning green time is devised. This novel controller mirrors the performance of either the cyclic or the non-cyclic controller depending on the geometry and demand. Large-scale simulation shows that this controller compares favorably with existing controllers using metrics of number of waiting vehicles and average travel time. Common problems with non-cyclic control include the higher likelihood of gridlock and the potential for very long waiting times when demand at a single intersection is asymmetric. On the other hand, the cyclic controller is required to allocate green time to every phase even if the demand is low, increasing the loss time. The novel semi-cyclic controller solves these inherent problems with the cyclic and non-cyclic controllers, making it more likely to be implemented by traffic engineers.
      Citation: Transportation Research Record
      PubDate: 2022-06-08T09:43:00Z
      DOI: 10.1177/03611981221095520
       
  • Impact of Cooperative Adaptive Cruise Control on Traffic Stability

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      Authors: Yun-Chu Hung, Kuilin Zhang
      Abstract: Transportation Research Record, Ahead of Print.
      Cooperative adaptive cruise control (CACC) is one of the popular connected and automated vehicle (CAV) applications for cooperative driving automation with combined connectivity and automation technologies to improve string stability. This study aimed to derive the string stability conditions of a CACC controller and analyze the impacts of CACC on string stability for both a fleet of homogeneous CAVs and for heterogeneous traffic with human-driven vehicles (HDVs), connected vehicles (CVs) with connectivity technologies only, and autonomous vehicles (AVs) with automation technologies only. We mathematically analyzed the impact of CACC on string stability for both homogeneous and heterogeneous traffic flow. We adopted parameters from literature for HDVs, CVs, and AVs for the heterogeneous traffic case. We found there was a minimum constant time headway required for each parameter design to ensure stability in homogeneous CACC traffic. In addition, the constant time headway and the length of control time interval had positive correlation with stability, but the control parameter had a negative correlation with stability. The numerical analysis also showed that CACC vehicles could maintain string stability better than CVs and AVs under low HDV market penetration rates for the mixed traffic case.
      Citation: Transportation Research Record
      PubDate: 2022-06-08T09:39:19Z
      DOI: 10.1177/03611981221094822
       
  • Design, Implementation, and Evaluation of a Roadside Cooperative
           Perception System

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      Authors: Rusheng Zhang, Zhengxia Zou, Shengyin Shen, Henry X. Liu
      Abstract: Transportation Research Record, Ahead of Print.
      Recently, with the advancement in autonomous driving, artificial intelligence, and vehicle-to-everything (V2X) communications, cooperative perception between roadway infrastructure and connected and automated vehicles via V2X communications has attracted increasing attention. However, most of the systems and prototypes reported are still at an initial stage. This paper introduces a newly developed and deployed roadside cooperative perception system with an edge-cloud structure and multiple kinds of sensors, including fisheye cameras, thermal cameras, and long-distance radars. The system is deployed at a roundabout at the intersection of State St. and W. Ellsworth Rd. in Ann Arbor, Michigan, U.S. With an edge-cloud structure, it can execute high-performance detection algorithms on edge devices at the field and collect data and analyze it on the cloud. The performance, in relation to detection rate, localization accuracy, and latency, is analyzed using the data collected from the field. These results show that the system has high potential for a wide range of applications, including infrastructure-vehicle cooperative perception, traffic data collection, and road safety studies. Two example applications—traffic volume monitoring and road safety warning—are introduced in the latter part of the paper to demonstrate the system’s capability.
      Citation: Transportation Research Record
      PubDate: 2022-06-08T09:34:21Z
      DOI: 10.1177/03611981221092402
       
  • Exploring Public Perception Toward Travel and COVID-19 Preventive
           Measures: Insights From the Early Stages of Lockdown in India

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      Authors: Kinjal Bhattacharyya, Saurabh Dandapat, Sai Kiran Annam, Kaustubh Saysardar, Bhargab Maitra
      Abstract: Transportation Research Record, Ahead of Print.
      The paper reports evidence related to peoples’ perceptions and attitude during the early stages of COVID-19 related lockdown in India in four major aspects: strategies and preventive measures, long-distance travel, essential services, and post-lockdown travel. A five-stage survey instrument was designed and circulated through various online modes to make it convenient to the respondents and also to achieve a greater geographical coverage within a short period of time. The survey responses were analyzed using statistical tools and the results are translated into potential policy recommendations which may be useful to implement effective interventions during future pandemics of similar nature. The findings highlight a high rate of awareness among the people about the COVID-19, lack of supply of protective equipment such as masks, gloves, and personal protective equipment kits during the early stage of lockdown in India. However, several heterogeneities were also observed across a few socio-economic groups which emphasize the need for targeted campaigns in a diverse country such as India. The findings also suggest the need for arranging safe and hygienic long-distance trips for a section of the society when such lockdown measures are extended for long periods. The observations related to mode choice preferences during the post-lockdown recovery period indicate a potential shift of public transport patronage to the personal modes.
      Citation: Transportation Research Record
      PubDate: 2022-06-06T11:27:17Z
      DOI: 10.1177/03611981221101032
       
  • How to Model the Effect of Gradient on Bicycle Traffic in Microscopic
           Traffic Simulation

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      Authors: Guillermo Pérez Castro, Fredrik Johansson, Johan Olstam
      Abstract: Transportation Research Record, Ahead of Print.
      Microscopic traffic simulation is a useful tool for the planning of motorized traffic, yet bicycle traffic still lacks this type of modeling support. Nonetheless, certain microscopic traffic simulators, such as Vissim, model bicycle traffic by applying models originally designed for car traffic. The gradient of a bicycle path has a significant impact on the speed of cyclists; therefore, this impact should be captured in microscopic traffic simulation. We investigate two calibration approaches to reproduce the effect of gradient on the speed of cyclists using the default driver behavioral model in Vissim. The first approach is to modify the simulated gradient to represent different values of the gradient-acceleration parameter: a fixed value that represents a decrease in the maximum acceleration that cyclists can apply on an uphill. The second approach is to adjust the maximum-acceleration function. We evaluate both approaches by applying a Vissim model of a bidirectional bicycle path with a 3% gradient in Stockholm. The results show that the current default implementation in the Vissim model underestimates the effect of gradient on speed. Moreover, the gradient-acceleration parameter does not directly reduce the maximum acceleration of all cyclists, but only of those cyclists riding above a certain speed. We conclude that by using a higher gradient-acceleration value than the default, we accurately estimate the observed mean speed on the uphill. However, neither of the investigated calibration approaches provides accurate estimates of the speed distributions. We emphasize the need for developing more accurate behavioral models designed for cyclists.
      Citation: Transportation Research Record
      PubDate: 2022-06-06T10:53:45Z
      DOI: 10.1177/03611981221094300
       
  • Beyond Start and End Points: Accessibility of Railway Stations on a
           Multi-Spatial Scale

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      Authors: Noriko Otsuka, Janina Welsch, Tiziana Delmastro, Roberta Delpiano, Stefano Pensa
      Abstract: Transportation Research Record, Ahead of Print.
      This paper presents results and policy implications from RAISE-IT, an EU Connecting Europe Facility (CEF) funded project. It examines the integration of long-distance rail with local and regional transport networks at key urban nodes along the Rhine-Alpine Corridor, one of the nine Trans-European Core Network Corridors (CNCs). It is crucial to foster seamless and suitable passenger transport solutions to achieve emissions goals and support the decarbonization process. Consequently, the whole travel chain needs to be considered and good interconnections with other transport modes are needed. For this reason, RAISE-IT explored multi-spatial scale accessibility. It considered three spatial scales (local, regional, and corridor-wide) and looked into multiple travel distances and needs along the corridor for accessing and minimizing the gap between highly and less accessible railway stations with reference to multi-scale travel patterns. This approach revealed overlapping issues between cross-regional and local decision makers and facilitated opportunities to discuss challenges and areas for improvement. The results formed the basis for guidelines on how to improve the accessibility of urban nodes and the quality of services and connections provided at railway stations. This paper discusses potential transferability aspects and recommendations for policy implications from RAISE-IT for railway stations and urban nodes in other CNCs.
      Citation: Transportation Research Record
      PubDate: 2022-06-06T10:52:53Z
      DOI: 10.1177/03611981221096116
       
  • Evaluating the Effects of Disruptions on the Behavior of Travelers in a
           Multimodal Network Utilizing Agent-Based Simulation

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      Authors: Mahsa Rahimi Siegrist, Beda Büchel, Francesco Corman
      Abstract: Transportation Research Record, Ahead of Print.
      Disruptions in transport networks have major adverse implications on passengers and service providers, as they can yield delays, decreased productivity, and inconvenience for travelers. Previous studies have considered the vulnerability of connections and infrastructures. Although such studies provide insights on general disruption management approaches, there is a lack of knowledge concerning integrated multi-level traffic management and its effects on travelers to reduce the impacts of disruptions. Integrated multi-level traffic management refers to coordinating individual network operations to create an interconnected mobility management system. This study sought to assess the management of road disruption utilizing multi-level disruption management. Multi-level disruption management is proposed that integrates an information dissemination strategy and allows changing the functionality of parking spaces to traffic lanes to facilitate the movement of travelers. The capacity/frequency of public transport vehicles is also increased to help travelers reach their destinations by changing to public transport mode. To achieve such goals, an extension to an agent-based simulation was developed. Numerical experiments are applied to a part of the city of Zürich. The results indicate that the proposed approach, multi-level disruption management in a multimodal network, can shorten travelers’ delays, especially comparing the effects of disruption management. Results show heterogeneity of behavior among agents. Adding lanes as a disruption management enhances the usage of car-mode by all agents, whereas it reduces the usage of car-mode by the directly affected agents, those who cannot pass the disrupted roads. In the presence of full information and increased capacity of transit vehicles, delay is reduced by 47%.
      Citation: Transportation Research Record
      PubDate: 2022-06-06T10:51:57Z
      DOI: 10.1177/03611981221094005
       
  • Long-Term Performance of Flexible Pavements Constructed on Recycled Base
           Layers

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      Authors: Hani Titi, Issam I. A. Qamhia, Jessie Ramirez, Habib Tabatabai
      Abstract: Transportation Research Record, Ahead of Print.
      There has been an increased interest in using reclaimed asphalt pavement (RAP) aggregates as a base course in Wisconsin for the offered economic and environmental benefits. Laboratory studies showed that RAP can have resilient modulus values higher than typical natural aggregates, and can also have higher durability, especially in freeze–thaw cycles. However, it is also recognized that RAP exhibits temperature sensitivity and larger permanent deformations than natural aggregates. How these characteristics manifest themselves in the northern U.S. climates can only be assessed by long-term observation of field performance. Wisconsin Department of Transportation (WisDOT) has been using RAP as a base course for over 30 years. The qualitative assessment of WisDOT roads constructed with RAP showed they are performing adequately. However, this impression has not yet been verified quantitatively. This paper presents a quantitative assessment and comparisons for field performance of pavement test sections constructed with RAP and natural crushed aggregate (CA) base course layers in Wisconsin. The performance was evaluated using pavement distress surveys of roadways containing RAP and CA, falling weight deflectometer (FWD), dynamic cone penetrometer (DCP) tests, and analysis of WisDOT’s available data. Based on the field evaluation, the performance of the hot mix asphalt (HMA) pavements with RAP was found adequate and comparable to those with CA base course layers. A recommendation was given that WisDOT shall continue the practice of using RAP in base course layers of HMA pavements, given proper quality checks for materials, and proper quality control/quality assurance measures being applied during construction.
      Citation: Transportation Research Record
      PubDate: 2022-06-06T07:07:42Z
      DOI: 10.1177/03611981221092000
       
  • Analysis of Indoor Guided Pedestrian Evacuation Dynamics in Single- and
           Multiple-Exit Scenarios: Toward a Unified Scheme for Guide Assignment

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      Authors: Ke Wang, Yongxing Li, Shunzhi Qian
      Abstract: Transportation Research Record, Ahead of Print.
      Indoor pedestrian evacuation processes could be significantly affected by the presence of guides, that is, safety management staff; how to assign guides properly remains a challenging task. This question is deconstructed into single- and multiple-exit scenarios for analysis in this study. The mechanisms behind the evacuation dynamics are explored via a two-layer guided pedestrian evacuation model and the corresponding guide assignment strategies are proposed. The upper layer model deals with guide assignment, where random and uniform guide assignment schemes, and a newly proposed distribution-based guide assignment scheme, are embedded, while the lower layer model controls the movement of evacuees based on a cellular automata model. Results show that there are bifurcate mechanisms governing evacuation dynamics. Only in single-exit scenarios could an increased number of guides lead to a “sharp decrease–long steady tail” tendency in total evacuation time, whereas evacuation efficiency in multiple-exit scenarios is consistent with exit use equilibrium. The three different guide assignment schemes bring about highly case-specific performances depending on the initial pedestrian distribution and the number of exits. The distribution-based guide assignment scheme is preferable in most cases, especially in spaces with a highly biased pedestrian distribution and multiple exits.
      Citation: Transportation Research Record
      PubDate: 2022-06-06T07:03:09Z
      DOI: 10.1177/03611981221094580
       
  • Maturity in Automated Driving on Public Roads: A Review of the Six-Year
           Autonomous Vehicle Tester Program

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      Authors: Xiaoyu Guo, Yunlong Zhang
      Abstract: Transportation Research Record, Ahead of Print.
      With support from United States Department of Transportation and state policies and regulations, in recent years manufacturers have initiated automated vehicle (AV) testing on public roads. Vehicle autonomy has grown from simulations and controlled environments to real-world driving environments with normal traffic. California is one of the states with an autonomous vehicle tester (AVT) program. It was established as early as 2014 for authorized manufacturers to test their AVs on public roads. This review examines permit holder information, autonomous mileage reports, autonomous vehicle disengagement reports, and autonomous vehicle collision reports over a six-year period. In addition to reviewing operating experience and the growth of AV testing, this study conducted in-depth analysis to evaluate maturity in automated driving technology and reported disengagement causes. It shows that a state-run AVT program boosts maturity in automated driving technology. At the same time, by participating in the AVT program, AV manufacturers showed a trend toward improvement in their AV technologies (e.g., an 8% fall in disengagements caused by hardware and software discrepancies and a 12% fall in those caused by perception discrepancies). States are encouraged to initiate or continue their AVT programs for the benefit of autonomous driving on public roads.
      Citation: Transportation Research Record
      PubDate: 2022-06-06T07:00:48Z
      DOI: 10.1177/03611981221092720
       
  • Numerical Simulations to Examine the Interaction of Train-Induced Guided
           Waves With Transverse Cracks

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      Authors: Korkut Kaynardag, Chi Yang, Salvatore Salamone
      Abstract: Transportation Research Record, Ahead of Print.
      This paper presents the results of a numerical study aimed at investigating the propagation of guided waves generated by train wheels on rails. The particular application of interest is to exploit such waves for the identification of transverse cracks located in the rail head. The research presented is part of an ongoing project aimed at developing a non-contact damage detection system based on laser Doppler vibrometer measurements. In this study, numerical simulations were carried out using three rail models. The first two models consisted of a transverse crack whose size is 20% and 10% of the rail head cross-section (RHC), respectively. The third model consisted of the same crack size as the first model, but it was designed to be longer before and shorter after the location of the crack compared with the first model. The goal of this model was to examine the location where the effect of cracks on the waves first appeared. To acquire train-induced guided waves to use in the simulations, an accelerometer was placed under a rail head, and propagating waves were recorded during the passage of an operating train. Afterward, on each rail model, the location of excitation and two measurement points were shifted forward over the rail to replicate the movement of the defect detection system. Two damage functions were used to examine the change in wave propagation caused by cracks, while a multi-dimensional damage index consisting of the damage functions was used to identify the location of the crack (20% of RHC).
      Citation: Transportation Research Record
      PubDate: 2022-06-06T06:53:26Z
      DOI: 10.1177/03611981221094576
       
  • In-Depth Understanding of Near-Crash Events Through Pattern Recognition

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      Authors: Xiaoqiang Kong, Subasish Das, Yunlong Zhang, Lingtao Wu, Jason Wallis
      Abstract: Transportation Research Record, Ahead of Print.
      Studying near-crashes can help safety researchers understand the nature of crashes from different perspectives. Conventional crash data sets lack information about what occurred directly before the crash event. This study used a near-crash data set extracted from a naturalistic driving study that includes features describing the vehicles, drivers, and information on other vehicles involved before and during the near-crash incidents. This data set provides us with a unique perspective to understand the patterns of near-crashes. This study applied the cluster correspondence analysis (cluster CA) algorithm to explore the patterns and the magnitude of each feature’s dominance within and between the clusters through dimension reduction. The analysis identifies six clusters with four types of near-crashes: near-crash with adjacent vehicles; near-crash with the following or leading vehicles; near-crash with turning vehicles; and near-crash with objects on the roadway. The results also show that the first two types of near-crash are the most common. The patterns for these two most common types of near-crash are different with or without the engagement of secondary tasks. The findings of this study provide a fresh perspective to understand different types of crash and associated patterns. Furthermore, these findings could help transportation agencies or vehicle designers develop a more effective countermeasure to mitigate the risk of collision.
      Citation: Transportation Research Record
      PubDate: 2022-06-06T06:50:06Z
      DOI: 10.1177/03611981221097395
       
  • COVID-19 and Injury Severity of Drivers Involved in Run-Off-Road Crashes:
           Analyzing the Impact of Contributing Factors

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      Authors: Seyedmirsajad Mokhtarimousavi, Angela E. Kitali, Jason C. Anderson, Priyanka Alluri, Armin Mehrabi
      Abstract: Transportation Research Record, Ahead of Print.
      This study examined the relationship between the lockdown during the COVID-19 pandemic and the severity of injuries sustained by drivers involved in run-off-road (ROR) crashes. A random parameter ordered logit (RPOL) modeling framework was utilized to account for the ordinal nature of severity outcome and capture the potential unobserved heterogeneity. The data used in this study contained ROR crashes that occurred in the state of Florida from April to September for 2019 and 2020 representing non-pandemic and pandemic time periods, respectively. Separate driver injury severity models were developed across the two time periods, and the overall stability of the model estimates was examined through likelihood ratio tests. The impacts of various potential contributing factors, including crash-, driver-, and vehicle-related variables, roadway geometric characteristics, environmental conditions, and traffic-specific factors, were assessed. Although the developed models share some common features, the analysis results showed that the model specifications indicated a strong temporal instability among the estimated parameters. Compared to the non-pandemic period, the following variables resulted in increased driver injury severity in ROR crashes during the pandemic: drivers 65 years or older, careless driving, and absence of traffic control devices.
      Citation: Transportation Research Record
      PubDate: 2022-06-06T06:47:46Z
      DOI: 10.1177/03611981221097093
       
  • Reclaimed Asphalt Pavement Binder Extraction and Recovery Evaluation and
           Their Effects on the Recycling Agent Assessment

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      Authors: Gustavo Pinheiro, Kamilla Vasconcelos, Liedi Bernucci
      Abstract: Transportation Research Record, Ahead of Print.
      The use of reclaimed asphalt pavement (RAP) has proved to be an advantageous alternative for the restoration and construction of new roads, with regard to the economical and environmental performance of the recycled material. However, one of the concerns about the use of RAP in the production of new asphalt mixtures is related to its inherent variability, manifested mainly in the asphalt binder. Some procedures to recover the aged binder are commonly used, such as extraction with solvents and recovery applying distillation techniques. These methods might change the intrinsic properties of the asphalt binder (e.g., rheological and chemical characteristics), which may lead to flaws in the dose of the recycling agent. The present study evaluated the variability of the techniques of asphalt binder extraction-recovery from a RAP source, and its effects on the final assessment of binder blend between RAP binder and a softer binder for recycled hot mix asphalt. The results show that automated extraction provided statistically satisfactory values for determination of the RAP binder content. The recovery method conditions, however, were not efficient with regard to solvent removal for 40% of the analyzed RAP samples. Pearson’s coefficients indicated a weak correlation between RAP binder aging indices and its rheological behavior, probably because of the presence of solvent. Tetrachlorethylene (TCE) spectrum band at wavelengths of 903 to 915 cm−1 tends to affect binder stiffness more than wavelengths of 771 to 783 cm−1, underestimating high temperature continuous performance grade ([math]) and consequently the binder blend results.
      Citation: Transportation Research Record
      PubDate: 2022-06-06T06:44:28Z
      DOI: 10.1177/03611981221094567
       
  • How to Measure the Network Vulnerability of Cities to Wildfires: Cases in
           California, U.S.A.

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      Authors: Jeongin Yun, Jooyoung Lee, Jangseop Park, Koohong Chung, Jinwoo Lee
      Abstract: Transportation Research Record, Ahead of Print.
      This paper proposes a framework to evaluate the network vulnerability of cities to wildfires. Three cities are selected from the California Public Utilities Commission (CPUC), U.S., fire-threat regions: Orinda, Paradise, and Atascadero. For each city, four different network connectivity measures are calculated, and agent-based evacuation simulations are performed by the Monte Carlo method. In the simulations, the number of isolated vehicles and evacuation time estimates are measured for the following scenarios: (i) no wildfire case with original network; and (ii) wildfire cases with randomly damaged networks that are reduced by 1%, 3%, 5%, 7%, and 10% from the original network. A city-to-city comparison is conducted in relation to network connectivity measures and evacuation simulation results. It is shown that Paradise has the worst network connectivity, and the simulation results reveal that Paradise also has the most sensitive network in relation to random roadway closures caused by wildfire propagation. Thus, among the three cities, Paradise has the most vulnerable network to wildfires as determined through the two analysis results concerning the worst network measures and the simulation results. It is expected that the proposed analysis framework can be generally applied to any city located in a fire-threat region.
      Citation: Transportation Research Record
      PubDate: 2022-06-04T10:43:02Z
      DOI: 10.1177/03611981221095516
       
  • A Reinforcement Learning Approach for Global Navigation Satellite System
           Spoofing Attack Detection in Autonomous Vehicles

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      Authors: Sagar Dasgupta, Tonmoy Ghosh, Mizanur Rahman
      Abstract: Transportation Research Record, Ahead of Print.
      A resilient positioning, navigation, and timing (PNT) system is a necessity for the robust navigation of autonomous vehicles (AVs). A global navigation satellite system (GNSS) provides satellite-based PNT services. However, a spoofer can tamper the authentic GNSS signal and could transmit wrong position information to an AV. Therefore, an AV must have the capability of real-time detection of spoofing attacks related to PNT receivers, whereby it will help the end-user (the AV in this case) to navigate safely even if the GNSS is compromised. This paper aims to develop a deep reinforcement learning (RL)-based turn-by-turn spoofing attack detection method using low-cost in-vehicle sensor data. We have utilized the Honda Research Institute Driving Dataset to create attack and non-attack datasets to develop a deep RL model and have evaluated the performance of the deep RL-based attack detection model. We find that the accuracy of the deep RL model ranges from 99.99% to 100%, and the recall value is 100%. Furthermore, the precision ranges from 93.44% to 100%, and the f1 score ranges from 96.61% to 100%. Overall, the analyses reveal that the RL model is effective in turn-by-turn spoofing attack detection.
      Citation: Transportation Research Record
      PubDate: 2022-06-04T10:40:43Z
      DOI: 10.1177/03611981221095509
       
  • ASPIRES: Airport Shuttle Planning and Improved Routing Event-driven
           Simulation

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      Authors: Qichao Wang, Devon Sigler, Zhaocai Liu, Andrew Kotz, Kenneth Kelly, Caleb Phillips
      Abstract: Transportation Research Record, Ahead of Print.
      Most of the existing traffic simulation packages require significant calibration work to be able to reflect reality. To evaluate special operations including emerging technologies, a microscopic simulation that tracks detailed interactions of all the elements of the traffic systems is usually needed. This type of simulation is usually computationally demanding. This work developed an Airport Shuttle Planning and Improved Routing Event-driven Simulation (ASPIRES) package to simulate and evaluate current, potential, and future airport shuttle operations. The simulation was driven by data and thus did not require much calibration effort. The discrete-event simulation nature of ASPIRES makes the simulation computationally efficient. Simulating 1 day of shuttle operations takes less than 2 s. The study site of this work is the Dallas/Fort Worth International Airport in the U.S. The shuttle service that connects the five terminals of the airport and the rental car center was studied. Travel times, dwell times, and passenger arrivals were simulated using empirical distributions derived mainly from real data to capture the stochastic nature of the rental car center shuttle bus operations. Data on bus miles traveled, bus energy consumption, passenger wait times, and passengers left behind at stops were collected to study the trade-off between energy use and passenger experience. Electric bus and on-demand bus operations were also included. The simulation outputs can show passengers statistics at terminals, shuttles statistics, and charging station statistics. ASPIRES cannot be used to model a generic traffic system but is well-suited for fleet systems.
      Citation: Transportation Research Record
      PubDate: 2022-06-03T08:16:06Z
      DOI: 10.1177/03611981221095744
       
  • Optimization of Platoons’ Lateral Position Based on Damage
           Estimation

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      Authors: Watheq Sayeh, Imad L. Al-Qadi
      Abstract: Transportation Research Record, Ahead of Print.
      Truck platooning is one of the upcoming paradigm shifts in roadway-traffic patterns. It is defined as a convoy of trucks moving with short distances between them; truck platoons will change the performance of pavements. This change could practically be realized with the emergence of connected and autonomous trucks, which can control their lateral position. In this study, optimal lateral position of truck platoons is defined. Using an efficient algorithm, pavement damage was estimated assuming a probabilistic position of trucks. Four typical pavement cross-sections were used to apply the algorithm-based optimization developed. The pavement sections varied in thickness and stiffness from thick and strong section to thin and weak. The optimization results showed that different schemes can be optimal for the same cross-section. However, most of these optimal schemes disperse the traffic throughout the lane. Compared with normally distributed truck traffic, up to 18% and 50% reduction in rutting and fatigue cracking, respectively, could be achieved when applying an optimized traffic pattern. When compared with a channelized-platoon traffic pattern, the optimized truck traffic shows prospects of reducing rutting and cracking up to 29% and 70%, respectively. Optimal traffic patterns were used to develop simple platoon factors that could be applied to the Illinois Mechanistic Design Method to incorporate truck platooning.
      Citation: Transportation Research Record
      PubDate: 2022-06-03T08:13:20Z
      DOI: 10.1177/03611981221095742
       
  • Safety Analysis for Micromobility: Recommendations on Risk Metrics and
           Data Collection

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      Authors: Elizabeth Karpinski, Eleanor Bayles, Tracy Sanders
      Abstract: Transportation Research Record, Ahead of Print.
      Existing measures of road safety were primarily designed to evaluate motor vehicle crashes. Consequently, they are not well-suited for alternate or emerging modes of micromobile transportation, particularly the e-scooter, whose popularity has surged without a corresponding body of research on their safety. Effective safety analysis depends on complete, high-quality data capable of accounting for the relevant mode-specific dangers. The established criteria for measuring consequences and hazard exposure in risk metrics used for motor vehicles do not apply. Most road safety data sources and schemas have a similar motor vehicle-centric bias. This framing presents challenges when it comes to selecting and interpreting data about alternate modes of transportation like micromobility. This paper discusses a basic theory of risk metric selection and the purpose of transportation safety measures. It applies these ideas to the emerging mode of micromobility transportation and recommends appropriate criteria and limitations for each component of a metric. This paper also evaluates existing data sources and schemas to provide examples of bias and estimate the relative size of each issue. These considerations may serve as useful guidelines for further research in the area and help inform the requirements of data collection necessary to better answer questions of safety.
      Citation: Transportation Research Record
      PubDate: 2022-06-03T08:10:01Z
      DOI: 10.1177/03611981221095523
       
  • Raised Pavement Marker Assessments Using Mobile Retroreflectivity Unit
           Technology

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      Authors: Alexander Oracheff, Ali Shahin, Charles Holzschuher, James H. Fletcher
      Abstract: Transportation Research Record, Ahead of Print.
      Currently, the Florida Department of Transportation (FDOT) State Materials Office collects 25,000 lane miles of line-stripe pavement marking (PM) retroreflectivity data each year using RoadVista Laserlux G7 (LLG7) mobile retroreflectivity units (MRUs). The focus of this study was to configure an LLG7 MRU to accurately and repeatably detect and measure the retroreflectivity of in-service Class B raised pavement markers (RPMs) while simultaneously collecting PM retroreflectivity data. At this time, FDOT assesses the quality of in-service RPMs as part of a visual inspection. Currently, there are no standards or devices for mobile RPM retroreflectivity measurements. As these LLG7 MRUs were designed to measure PMs in units of RL (mcd/m2/lux), an additional objective was to derive regression equations that correlate the industry-standard units for RPMs (RI [mcd/lux]) and the RL values collected by the MRU. Through research-based experiments and with coordination from RoadVista, modifications were made to the LLG7 MRU to detect and measure RPM retroreflectivity in relation to RL. Regression equations were derived pertaining to retroreflectivity measurements between a handheld RPM retroreflectometer (RI) and an LLG7 MRU (RL) on in-service RPMs. The results indicate that the modified MRU can be used to effectively assess RPM retroreflectivity in tenth-mile intervals in a highly repeatable manner with an average error in estimated RI of ±13.5% without affecting PM data. Overall, utilizing the modified MRU for statewide RPM assessments is a significant improvement from the current process of visual assessments and allows the FDOT to quantify RPM quality on a network level.
      Citation: Transportation Research Record
      PubDate: 2022-06-03T08:06:58Z
      DOI: 10.1177/03611981221095086
       
  • Comparison of Relative Structural Characterization Methods for
           Additive-Modified Asphalt Mixtures

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      Authors: David H. Timm, Fan Yin, Nam Tran, Megan Foshee, Carolina Rodezno
      Abstract: Transportation Research Record, Ahead of Print.
      The evaluation, adoption, and efficient deployment of asphalt additives in flexible pavements has historically been a relatively slow process, requiring years of testing and evaluation before a new product may be fully and readily used in pavement cross-sections. However, the fast-paced and innovative nature of the additive marketplace produces numerous products that have the potential to improve performance, reduce costs, or both, but have been hindered by slow deployment. To address the need for a more rapid set of evaluation tools, the National Center for Asphalt Technology Test Track initiated an Additive Group experiment in 2021 to build full-scale pavement test sections modified with several asphalt additives, including recycled tire rubber, recycled plastics, reactive polymers, and aramid fibers. Data will be collected from these test sections to develop a framework for evaluating asphalt additives in the future. Phase 1 of the investigation was to conduct limited laboratory testing and structural analysis from which a group of additives would be selected for full-scale construction and evaluation. Focused on fatigue cracking, this paper details the laboratory testing conducted for Phase 1 and two different structural pavement analysis methods using FlexPAVE™ and WESLEA. Even though the two structural pavement analysis methods are very different, the FlexPAVE and WESLEA analyses provided strongly correlated predicted cracking performance, remarkably similar predictions of equivalent pavement thicknesses, and nearly identical structural layer coefficients. It is recommended that these two approaches be further evaluated against laboratory and field performance data that will be collected from the Additive Group experiment.
      Citation: Transportation Research Record
      PubDate: 2022-06-03T07:36:10Z
      DOI: 10.1177/03611981221094583
       
  • Ten Years of Traffic Speed Deflectometer Research in the United States: A
           Review

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      Authors: Samer Katicha, Gerardo Flintsch, Brian Diefenderfer
      Abstract: Transportation Research Record, Ahead of Print.
      This paper summarizes the research efforts into and applications of the traffic speed deflectometer (TSD) that have occurred over the last 10 years in the United States (U.S.). These are divided into three main topics which are: (1) data analysis methods including data processing, calculation of indices and structural parameters, and temperature correction; (2) evaluation efforts of TSD including repeatability and comparison with the falling weight deflectometer (FWD); and (3) applications of TSD with a focus on flexible pavement management applications, although some efforts on rigid and composite pavements are mentioned. The data analysis methods reviewed are data averaging length and reporting interval, and how deflections are calculated from the measured deflection slopes. For the calculation of indices and structural parameters the following are reviewed: deflection indices that have been proposed, the effective structural number (SNeff), and backcalculation of layer moduli. Efforts to evaluate TSD precision (or measurement standard error) are discussed. Then, some comparisons of short-term (time frame of 1 day) and long-term (time frame of 1 year) repeatability of TSD are presented. Compared with FWD, TSD and FWD generally have good correlation, although the measurement principles of the two devices are slightly different. The focus is on network-level applications of TSD, and, more specifically, efforts to include TSD measurements in the pavement management system, especially for flexible pavements applications.
      Citation: Transportation Research Record
      PubDate: 2022-06-03T07:33:31Z
      DOI: 10.1177/03611981221094579
       
  • Analysis of Intrinsic Factors Leading to Aggressive Driving Behavior to
           Derive Safety Policy Implications for Bus Drivers

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      Authors: Eunsol Cho, Subin Park, Cheol Oh
      Abstract: Transportation Research Record, Ahead of Print.
      Significant efforts to develop effective safety policies are essential to prevent bus traffic accidents because city buses accommodate many passengers. An in-depth analysis of causal factors that can be the intrinsic cause of aggressive driving is a first step toward preparing for effective bus safety policies. This study aims to explore traffic safety policy implications and analyze development priorities based on the aforementioned factors including the working environment, health characteristics, human characteristics, living environment, and bus route characteristics. Bus driver survey data obtained by self-reported survey instruments were used to discover factors that affect aggressive driving behavior captured by an in-vehicle data recorder. A binary logistic regression model was established using driver characteristics as independent variables and the level of aggressive driving behavior as the dependent variables. From the model, a total of nine independent variables that have a statistically significant effect on aggressive driving behavior by bus drivers were found. This study then suggested seven bus safety policy implications based on the identified influencing factors. The results of the prioritizing the policy implications show that detailed regulations related to break times for city bus drivers, improvement of company break rooms, and management measures for bus driver mental health and psychological conditions were the top three. The findings of this study would be valuable for the development of effective traffic safety policies that reflect the characteristics of the city bus industry.
      Citation: Transportation Research Record
      PubDate: 2022-06-03T07:30:28Z
      DOI: 10.1177/03611981221094574
       
  • Performance Dashboard Tool to Visualize Adaptive Resilience Maturity of
           Transportation Agencies

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      Authors: Prerna Singh, Adjo Amekudzi-Kennedy, Habte Kassa
      Abstract: Transportation Research Record, Ahead of Print.
      Incorporating adaptive resilience as a core value of transportation systems will equip transportation agencies to better address the increasing pace of future changes—both in climate and transportation system performance demands. Quantifiable measures are instrumental in incorporating adaptive resilience in agency organizational frameworks. This paper presents a dashboard tool that evaluates the maturity of adaptive resilience capabilities of a transportation agency, using an Adaptive Resilience (AR) Capability Maturity Model. A demonstrative example is presented to show the potential application of the dashboard tool and its implications for transportation system resilience planning. The example shows how the tool can facilitate identification of adaptive resilience capabilities that are at low maturity and thus may need prioritization for future resilience investments, and capabilities that are at a high maturity level and thus can be leveraged to enhance the lower-level capabilities. The AR performance dashboard tool may be used by transportation agencies to communicate their adaptive resilience efforts and maturity to stakeholders. It can also be used by practitioners to streamline and prioritize process improvements in adaptive resilience efforts.
      Citation: Transportation Research Record
      PubDate: 2022-06-03T07:28:49Z
      DOI: 10.1177/03611981221092404
       
  • Application of Geographic Information Systems in Impact Evaluation and
           Geospatial Portfolio Analysis of Transport Projects

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      Authors: Toshiyuki Yokota, Homer Pagkalinawan
      Abstract: Transportation Research Record, Ahead of Print.
      New technologies and global datasets enable transport projects to be assessed more effectively and efficiently. Geospatial data are available retrospectively and remotely, which is particularly useful for evaluators working in countries with constraints on their access to data, including those caused by COVID-19 pandemic. Another advantage is that data quality is the same and comparable across countries. This paper reports the results of geospatial portfolio analysis and economic impact analysis with geospatial data. It generated several interesting findings. For example, the contribution of projects carried out by the Asian Development Bank (ADB) became visible, as about 290 million people live along the road alignments of ADB projects and are therefore potential beneficiaries. Their presence and greater economic activity are indicated by increases in the radiance of nighttime light. The data also demonstrated which countries need to make additional efforts to reduce CO2 emissions from the project areas. Two levels of impact analysis using nighttime light were carried out, which measured local benefits of economic growth. The first assessed a national highway project in Armenia. The contribution of the project to economic growth was more than 2.5% per year. The second found that 33 transportation projects had made an average annual contribution to economic growth of 5%. The authors compared the impact assessed by nighttime light with conventional economic analysis using economic internal rates of return, measuring benefits enjoyed by road users and administrators, and observed a positive correlation between the two.
      Citation: Transportation Research Record
      PubDate: 2022-06-02T12:40:33Z
      DOI: 10.1177/03611981221092007
       
  • Are New Pavement Condition Indices Necessary for Long-Poor Pavements'

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      Authors: Thomas Calhoon, Mihai Marasteanu, Shannon McGrath
      Abstract: Transportation Research Record, Ahead of Print.
      In Minnesota, pavements are considered to be in poor condition when the ride quality index (RQI) is less than or equal to 2.0. However, because there are pavement sections that have remained in poor condition for multiple years, it is not clear whether RQI accurately quantifies the “true” condition of certain sections. In this study, sections that had maintained a poor RQI over time were identified in each district and extensive additional information was obtained from interviews with district engineers and planners. The analysis of the additional information showed that most pavement sections that had remained in poor condition for extended periods were not in poor condition. They represent “anomalies” with unique characteristics, and new parameters must be established to quantify the true condition of these sections.
      Citation: Transportation Research Record
      PubDate: 2022-06-02T12:36:45Z
      DOI: 10.1177/03611981221092004
       
  • Mitigating Pumping in Pavement Shoulder Using Wicking Geotextile: An
           Experimental Study

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      Authors: Javad Galinmoghadam, Jenny Liu, Xiong Zhang, Chuang Lin, Yipeng Guo
      Abstract: Transportation Research Record, Ahead of Print.
      Pumping is one of the major factors contributing toward concrete pavement failures, one which reduces the pavement life, affects road safety, and increases maintenance costs. Existing methods such as nonwoven geotextiles used as drainage systems can drain gravitational (free) water under saturated conditions but not the capillary water under an unsaturated conditions. The objective of this study is to explore and identify the feasibility of using a new wicking geotextile for pumping mitigation in pavement shoulder via laboratory tests and field test section monitoring. Laboratory results showed that soil installed with wicking geotextile was noticeably drier than that with a French drain as a drainage system because the wicking geotextile can drain capillary water. Nearly 3 years of field monitoring verified the effectiveness of using wicking geotextile to reduce water content, especially where the pavement was prone to pumping damage. In addition, exposing the edge of the wicking geotextile to the air further noticeably increased its drainage ability.
      Citation: Transportation Research Record
      PubDate: 2022-06-02T12:33:48Z
      DOI: 10.1177/03611981221091730
       
  • Molecular Agglomeration Index: Quantification of the Incidence of
           Asphaltene Molecular Agglomeration in Aged Asphalt Binders Through
           Rheological Measurements

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      Authors: Rodrigo Shigueiro Siroma, Mai Lan Nguyen, Pierre Hornych, Tristan Lorino, Yvong Hung, Aurélia Nicolaï, Layella Ziyani, Emmanuel Chailleux
      Abstract: Transportation Research Record, Ahead of Print.
      The phase angle (φ) has long been recognized as a powerful tool to detect variations in asphalt binders’ chemistry and microstructure. A recent study applied unsupervised multivariate approaches to uncover hidden pattern structures in data sets and settled the most relevant reduced frequency to investigate the evolution of the phase angle master curve with aging. Considering that study’s findings, this paper revisits the δ-method—that is, an approach that estimates the apparent molecular weight distribution (AMWD) of a given asphalt binder based on its rheology—and proposes a simple indicator that quantifies the incidence of asphaltene molecular agglomeration named Molecular Agglomeration Index (MAI). Laboratory- and field-aged binders were tested and a limiting value for MAI indicating an increased binder cracking susceptibility is established in agreement with other failure criteria found in the literature.
      Citation: Transportation Research Record
      PubDate: 2022-06-02T12:29:47Z
      DOI: 10.1177/03611981221088597
       
  • Access Benefits of Shared Autonomous Vehicle Fleets: Focus on Vulnerable
           Populations

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      Authors: Jooyong Lee, Kara M. Kockelman
      Abstract: Transportation Research Record, Ahead of Print.
      This research monetizes the access benefits of making shared autonomous vehicles (SAVs) available to residents of Texas’ Dallas-Fort Worth metroplex in the U.S. Residents’ willingness to pay for SAV access under different fares and modes was estimated and compared across the region’s 5,386 traffic zones, with emphasis on those housing the regions’ most vulnerable or access-limited travelers. Assuming a $0.50/mi SAV fare, the average per-person-trip benefit is estimated to be $0.64 per trip. With $0.50/mi SAV fare, HV mode share will be reduced from 92.4% to 40.3%, while SAV will take 55.8% of the share. However, if HVs are then disallowed (removed from everyone s mode choice set) after $0.50/mile SAVs have been added, the average net impact is estimated to be −$0.31 per trip, across the metroplex. If HVs were to be replaced by access to SAVs, the impacts are positive, with region-wide average access benefits ranging from $0.16 to $0.33 per trip, depending on the SAV fare, and urban zones have a greater access benefit than rural zones with low SAV fare.Vulnerable populations and their neighborhoods were identified based on the share of persons living below the poverty level, income per capita, share of persons aged 65 years or older, those with disabilities, those owning no vehicle, and share of persons from a racial minority group. Results suggest that the access benefits of SAVs will be higher in locations/neighborhoods housing more vulnerable populations, but some vulnerabilities (e.g., those over age 65) results in lower levels of access improvement. Across those zones with highest shares of vulnerable persons, the range of differences in welfare impacts, from adding SAVs to travelers mode choice sets, widened as fares rose. As is true with many innovations, careful attention to disadvantaged groups and thoughtful policy (via smart contracting and SAV-user subsidies by public agencies, for example) can better ensure valuable access improvements for those with limited mobility and resources.
      Citation: Transportation Research Record
      PubDate: 2022-06-02T12:26:22Z
      DOI: 10.1177/03611981221094305
       
  • Incorporation of Human Factors to a Data-Driven Car-Following Model

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      Authors: Michael Harth, Uzair Bin Amjad, Ronald Kates, Klaus Bogenberger
      Abstract: Transportation Research Record, Ahead of Print.
      In recent years, there have been intensive efforts to consider human factors (HFs) in the modeling of human driver behavior. In particular, “engineering” car-following models widely used in traffic simulation have been extended to include HFs. This extension is needed to generate critical situations, which are often attributable to human error. However, incorporation of reaction processes requires advanced models that take driver predictions and delayed responses into account. In this paper, a methodology for integrating HFs into driver behavior modeling is developed based on a long short-term memory architecture. The proposed methodology employed a three-layer psychological concept: perception, information processing, and action. The perception layer modeled (imperfect) estimation of visually received stimuli. Information processing included short-term memory and the projection of perceived stimuli into the near future. The executed action, based on the sensed as well as anticipated dynamic driving state, was delayed by the perception–reaction time. To represent individual differences among driver types, the available training dataset was classified in four clusters according to observable driver characteristics. The methodology was demonstrated with data recorded at an urban signalized intersection. Model performance was compared with that of two established engineering models, the intelligent driver model and the (extended) full velocity difference model. The results indicated that the human driver model developed here showed superior performance in replicating real-world trajectories compared with existing models and was able to represent the varying driving strategies of different groups.
      Citation: Transportation Research Record
      PubDate: 2022-06-02T12:23:17Z
      DOI: 10.1177/03611981221089316
       
  • Effect of Swelling Soil on Pavement Condition Index of Airport Runway
           Pavement

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      Authors: Md Tofail Miah, Erwin Oh, Gary Chai, Phil Bell
      Abstract: Transportation Research Record, Ahead of Print.
      Swelling is one of the distresses that affect the pavement condition index (PCI) of airport runways. In northwest Queensland, swelling was observed in three different runways where sealed flexible pavement runways were deformed by the heaving of the expansive clay subgrades due to water intrusion. In the study, the trends of moisture content (MC) and corresponding swelling of these expansive soils were observed at different times. Subsequently, the PCI was calculated for the swelling of these runways using PAVER software. A correlation has been developed between swelling of different severity levels and the corresponding PCI. In addition, the relationship between MC and PCI has been established to demonstrate the influence of MC on the swell behavior, and the influence of seasonal MC variations on PCI was also examined. Finally, the study generated empirical equations to predict the swelling effects on the PCI and subsequent functional performance of the runway pavements constructed on expansive soils. A good correlation has been achieved between the swell parameter and the PCI. The correlation coefficient of determination R2 is computed to be 0.9981, 0.999, and 0.9987 for low, medium, and high severity of the swelling, respectively. The equations fitted with the experimental data well, which demonstrates the reliability of the empirical equations. From the result of swelling against MC and calculated PCI, it is evident that adverse effects are inevitable when water intrusion occurs in swelling soil subgrade. This high plasticity soil can deteriorate pavement performance and cause early pavement damage if allowed to swell.
      Citation: Transportation Research Record
      PubDate: 2022-06-02T12:19:17Z
      DOI: 10.1177/03611981221090517
       
  • Development of a Screening Tool for Rapid Fly Ash Evaluation for
           Mitigating Alkali Silica Reaction in Concrete

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      Authors: Pravin Saraswatula, Anol Mukhopadhyay, Kai-Wei Liu
      Abstract: Transportation Research Record, Ahead of Print.
      Performance-based approaches to evaluate fly ash effectiveness in suppressing alkali silica reaction (ASR) require testing for a range of replacement levels to determine optimum fly ash dosage. Current approaches of ASR evaluation, that is, determining optimum fly ash dosage for ASR mitigation, are impractical as a mix design tool for new concrete construction. Therefore, in the present work a screening tool is developed to predict optimum fly ash dosage to suppress ASR in concrete mixes. The screening tool uses water-soluble (readily available) alkali from fly ash and cement to determine pore solution alkalinity (PSA) of concrete mixes for different fly ash replacement levels. The optimum fly ash dosage in concrete to mitigate ASR is estimated based on the PSA and aggregate threshold alkalinity (THA) relationship, that is, PSA should be ≤THA to make the mix ASR mitigated. Results from the screening tool demonstrate an 82% reliability in predicting fly ash dosage necessary to keep expansions below 0.04% based on AASHTO TP 142 tests for ASR expansion. In addition, a multiple non-linear regression model was developed to predict water-soluble alkali from fly ashes in place of testing using 50 experimental data points from laboratory measurements and literature studies. Overall, the screening tool presents a rapid and reliable approach to determine the optimum fly ash content required for ASR mitigation based on pore solution composition of mixes and aggregate reactivity.
      Citation: Transportation Research Record
      PubDate: 2022-06-01T12:29:41Z
      DOI: 10.1177/03611981221094291
       
  • Improving Spatiotemporal Transferability of Real-Time Crash Likelihood
           Prediction Models Using Transfer-Learning Approaches

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      Authors: Pei Li, Mohamed Abdel-Aty, Shile Zhang
      Abstract: Transportation Research Record, Ahead of Print.
      A real-time crash likelihood prediction model is an important component of the proactive traffic safety management system. Over the past decades, numerous models have been proposed for predicting real-time crash likelihood and achieved promising results. However, most studies have ignored the model transferability, especially for deep-learning models. The transferability of a model could be defined as applying the model to new data which obtain from different locations or periods. The purpose of this study is to improve the spatiotemporal transferability of a deep-learning crash likelihood prediction model by using transfer-learning approaches. Trajectory and crash data from five arterials in Florida were used in this study. A two-layer long short-term memory (LSTM) model was developed to predict real-time crash likelihood. Two scenarios were created for investigating spatial and temporal transferability of the developed model. Experimental results suggested that the model could be accurately transferred to new data by using the fine-tuning transfer-learning approach. In the framework of this research, the transferred models achieved higher predictive accuracy than models which were directly developed on the new data. Moreover, the spatial transfer learning outperformed the temporal transfer learning in predictive accuracy. For example, when the percentage of test data was 70%, the spatial transferred model had an average area under the curve (AUC) of 0.74. while the temporal transferred model had an average AUC of 0.65. Results from this study could be applied to transfer pretrained crash likelihood prediction models to new locations when few crashes are available.
      Citation: Transportation Research Record
      PubDate: 2022-06-01T12:26:13Z
      DOI: 10.1177/03611981221094289
       
  • Implementation of Finite Element and Fracture Mechanics Based Reflection
           Cracking Models for Asphalt Concrete Overlay of Existing Asphalt Concrete
           Pavement in AASHTOWare Pavement ME Design

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      Authors: Leslie Titus-Glover, Biplab B. Bhattacharya, Deepak Raghunathan
      Abstract: Transportation Research Record, Ahead of Print.
      The reflection of existing cracks from the underlying pavement is one of the primary modes of failure for rehabilitated asphalt concrete (AC) pavements with AC overlays. The AC overlay design philosophy is to delay the onset of reflection cracking or to eliminate it entirely. In recent years, rehabilitation designs are being optimized not just for cost effectiveness, but also to produce more reliable, sustainable, and environmentally friendly designs that require more detailed and sophisticated methodologies. The new finite element and fracture mechanics based reflection cracking models were developed under National Cooperative Highway Research Program (NCHRP) Project 1-41 to improve design methodology. The new models were generally compatible with the AASHTOWare Pavement ME Design (AASHTOWare) framework. The difference included the computation of critical pavement responses (i.e., stress intensity factors) and others, and thus modified. The modified models were calibrated and validated using Long-Term Pavement Performance projects. The calibration of reflection cracking models produced satisfactory goodness of fit with no significant bias. Thus, the modified reflection cracking models were successfully adapted and deployed in the AASHTOWare software to create a new improved AC overlay of existing AC pavement design methodology. This new methodology represents a paradigm shift from the traditional pavement design procedures. It significantly increases the capability of the pavement design software to simulate all the loadings experienced by AC overlay, estimate pavement responses, and predict reflection cracking based on pavement responses. This paper discusses the implementation of NCHRP 1-41 reflection cracking models for AC overlay of existing AC pavements into AASHTOWare software.
      Citation: Transportation Research Record
      PubDate: 2022-06-01T12:22:59Z
      DOI: 10.1177/03611981221094004
       
  • Exploring Agent-Based Modelling for Car-Based Volunteer Driver Program
           Planning

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      Authors: Romaine Morrison, Trevor Hanson
      Abstract: Transportation Research Record, Ahead of Print.
      Volunteer driver programs (VDPs) utilize the service of volunteers to replicate car-based, demand-responsive, door-to-door services in rural areas, but little is understood about how external factors (e.g., changes in service area) affect VDP sustainability. Agent-based modelling (ABM) simulates the operational behavior of individual agents (e.g., drivers, users) to evaluate their interaction under specified scenarios, and although it has been used in transportation research, it has never been applied to VDP analysis. Netlogo was used to develop a simplified VDP ABM, calibrated and validated with 1 year of program data from the New Brunswick Volunteer Driving Database. Three model scenarios were tested: increased health trip distance, increased service area, and increasing the number of drivers to meet initial distance targets. The ABM demonstrated intuitive results and established connections among changing operational scenarios, though additional research is needed for multipurpose trips and user/driver/dispatcher interactions.
      Citation: Transportation Research Record
      PubDate: 2022-06-01T12:19:59Z
      DOI: 10.1177/03611981221093998
       
  • Pavement Recycling in Cold Climates: Laboratory and Field Performance of
           the MnROAD Cold Recycling and Full Depth Reclamation Experiment

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      Authors: David Allain, Benjamin F. Bowers, Adriana Vargas-Nordcbeck, Tiana Lynn
      Abstract: Transportation Research Record, Ahead of Print.
      In 2019 a series of test sections were constructed on 70th Street in Albertville/Otsego, MN. The existing roadway was badly deteriorated with an international roughness index value above 300 in./mi, which places it in a “poor” performance category. A combination of treatments including cold in-place recycling (CIR), cold central plant recycling (CCPR), and full depth reclamation (FDR) stabilized with foamed or emulsified asphalt were used to evaluate performance in cold regions. Sections including a typical hot mix asphalt (HMA) mill and fill were also evaluated. All sections contained a 1-in. HMA thinlay as the wearing surface. This paper presents the laboratory testing data for the mixtures, including application of HMA tests not typically applied to CIR, CCPR, and FDR, the field performance to date, and a new approach to connecting laboratory data to field performance.
      Citation: Transportation Research Record
      PubDate: 2022-06-01T12:16:33Z
      DOI: 10.1177/03611981221093997
       
  • Validation of Agent-Based Passenger Movement Modeling for Railway Stations
           Subject to Social Distancing During the COVID-19 Pandemic

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      Authors: Sam Hayes, John Charlton, David Fletcher, Paul Richmond
      Abstract: Transportation Research Record, Ahead of Print.
      The COVID-19 pandemic has caused unprecedented difficulties keeping passenger transport running while social distancing has constrained pedestrian movement. To support railway operation an agent-based simulation validated against UK mainline railway station CCTV footage has been developed. The simulation quantifies train alighting- and boarding flow times for different degrees of distancing, rolling stock types, platform size, and passenger numbers. Real-world social distancing behavior was represented, including compromises people make on distancing to achieve their goals. Flow times modeled and those measured from CCTV were within 10%. Relative to a baseline without social distancing, 1-m distancing was predicted to make only a marginal difference to passenger flow times, primarily because of passenger behavior to compromise on distancing at the rate determining door location. For 2-m social distancing, significantly extended passenger alighting and boarding flow times were predicted for busier services (i.e., 2.2 to 2.8 times baseline depending on rolling stock type). These increases in flow time are only predicted to begin when the combined total of boarding and alighting passengers exceeds 10 to 15 per door. The model has applications in transport systems worldwide in avoiding unmaintainable timetables, and in reducing incentives for social distancing compromise when distancing forms a component of suppressing virus transmission.
      Citation: Transportation Research Record
      PubDate: 2022-06-01T12:14:13Z
      DOI: 10.1177/03611981221093634
       
  • Optimal Design of Pouring Semi-Flexible Pavement via Laboratory Test,
           Numerical Research, and Field Validation

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      Authors: Senlin Ling, Zhongbo Chen, Daquan Sun, Hangtian Ni, Yue Deng, Yu Sun
      Abstract: Transportation Research Record, Ahead of Print.
      Pouring semi-flexible pavement (SFP) material is a multi-phase composite with excellent pavement performance, which consists of porous asphalt mixture (PAM) and grouting material. This research is to investigate the optimal design of SFP for the upper pavement layer in relation to air void and thickness. Firstly, the effect of PAM with different air voids on the mechanical performance of SFP is investigated by uniaxial compression tests. Secondly, the influence of the air void of PAM on the rutting resistance and water sensitivity of SFP is analyzed by wheel tracking test and Hamburg wheel tracking (HWT) test. Then, the optimal thickness of SFP is investigated by 3D finite element analysis. Finally, based on the experimental and numerical results, SFP is applied to practical engineering and the field performance was inspected. The results show that increasing the air void of PAM can significantly improve the mechanical properties and rutting resistance of SFP. However, when the air void of PAM is 25%, SFP has the highest strain energy density. According to the experimental and numerical results, as well as the construction cost of SFP, the optimal thickness range of 4–8 cm is recommended for the SFP layer. Moreover, the field performance inspection results show that after nearly 2 years of service, pavement using SFP with PAM air void of 25% and thickness of 4 cm for the upper layer has excellent rutting resistance, impermeability, and high wear resistance, which allows for undergoing heavy traffic loads.
      Citation: Transportation Research Record
      PubDate: 2022-06-01T12:11:13Z
      DOI: 10.1177/03611981221093631
       
  • Effects of Aggregate/Filler Characteristics on Semi-Circular Bend Fracture
           Parameters of Asphalt Concrete Mixtures Subject to Moisture Damage

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      Authors: Rodolpho Medeiros Frossard, Jamilla Emi Sudo Lutif Teixeira, Yong-Rak Kim
      Abstract: Transportation Research Record, Ahead of Print.
      The binder–aggregate adhesiveness plays an important role in preventing asphalt concrete adhesive fracture and it is greatly influenced by the chemical, physical, morphological, and mineralogical properties of aggregates. Many studies have attempted to assess fracture resistance of asphalt mixtures by evaluating parameters found from different laboratory fracture tests. Those parameters are related to the mixture components, and they can change when moisture conditions are induced. This study aims to investigate the effects of aggregate/filler characteristics on mixture fracture resistance including the effect of moisture damage. Two aggregates and four fillers with varied chemical compositions were selected and combined with one unmodified asphalt binder to design five different asphalt mixtures. Each aggregate and filler was tested to characterize physical, chemical, and morphological properties. Asphalt concrete mixtures samples, with and without being subjected to moisture conditioning, were submitted to the semi-circular bend (SCB) fracture test. Statistical analyses were performed to determine the level of significance on the parameter change resulting from the properties of particles and moisture conditioning. The results indicated that the type of aggregates did not present significant influence on the SCB fracture results when moisture conditioning was not involved. Also, the type of filler presented different trends on the parameter’s change when the samples were subjected to moisture. However, it was observed that the effects of aggregates and fillers on the fracture resistance of asphalt mixtures were pronounced when the SCB samples were subjected to moisture conditioning, because of the material-specific binder–aggregate adhesion in the presence of moisture.
      Citation: Transportation Research Record
      PubDate: 2022-06-01T12:08:53Z
      DOI: 10.1177/03611981221093329
       
  • Developing Capacity Estimation Metrics for Airports Accommodating Smaller
           Aircraft Using Locally Collected Automated Dependent
           Surveillance-Broadcast Data

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      Authors: Danae Zoe Mitkas, David J. Lovell, Seth B. Young, Sandeep Venkatesh
      Abstract: Transportation Research Record, Ahead of Print.
      Airport operators need good capacity estimates for many purposes, including to bolster applications for funding support for capacity improvements. Based on a recognized need to enhance models for estimating the operating capacity of airports serving a user base of smaller aircraft, such as small general aviation airports, this paper describes research conducted to leverage automated dependent surveillance-broadcast (ADS-B) data to develop aircraft performance characteristics for use as inputs to future small airport capacity models. The research addresses this challenge by constructing home-built ADS-B data collection units using a Raspberry Pi-based hardware platform and an Amazon Web Services-based cloud architecture housing the study’s PostGreSQL database, and python-based codebase. The work was focused at three participating airports: The Ohio State University Airport in Columbus, OH (KOSU); College Park, MD (KCGS); and Republic Airport in Farmingdale, NY (KFRG). The hardware units were deployed at three study airports, collecting more than 90 million individual ADS-B messages transmitted by aircraft operating within the vicinity of the study airport. Models were developed to clean, process, and assess the data, and leveraged to determine aircraft performance characteristics within these environments. Initial work focusing on assessing the fleet mix, approach speeds, aircraft separation in arrival streams, and runway occupancy times was performed. Findings from this research revealed a very high accuracy and richness of collected and processed data, and performance metrics that were reasonable, valid, and applicable for use as inputs to future airport capacity models.
      Citation: Transportation Research Record
      PubDate: 2022-06-01T11:59:07Z
      DOI: 10.1177/03611981221092384
       
  • Investigating the Influence of Joint Reinforcements of Portland Cement
           Concrete Slabs Under Asphalt Concrete Overlays on Vertical Deflections
           Using Accelerated Pavement Testing

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      Authors: Mehmet Tevfik Seferoğlu, Ayşegül Güneş Seferoğlu, Muhammet Çelik, Muhammet Vefa Akpinar
      Abstract: Transportation Research Record, Ahead of Print.
      Joint gaps between slabs in underlying Portland cement concrete (PCC) pavements are critical factors in the life span of asphalt concrete (AC) overlays. Therefore, being informed about the vertical deflections that may occur around the joints is important. In this study the joints were reinforced with three different materials: ethylene propylene diene monomer (i.e., rubber joint filler [RJF] reinforcement), bitumen-based sealant (i.e., rubber plate [RP] reinforcement), and steel plate (SP) (i.e., SP reinforcement), to limit the vertical movement of the underlying PCC. Tests were conducted at the accelerated pavement testing facility for two different AC overlay thicknesses, 50 mm and 100 mm, during 100,000 passages to investigate the influence of AC overlay thickness variations on slab vertical deflections and to also evaluate types of joint reinforcement on slab vertical deflections. For 50-mm thick AC overlay, the most effective joint reinforcements to prevent deformations caused by loading were RP, RJF, and SP; for a 100-mm thickness, this was determined to be RJF, SP, and RP, respectively.
      Citation: Transportation Research Record
      PubDate: 2022-06-01T11:54:43Z
      DOI: 10.1177/03611981221092380
       
  • Estimating Route Choice Characteristics of Truck Drivers from Sparse
           Automated Vehicle Identification Data through Data Fusion and Bi-Objective
           Optimization

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      Authors: Salil Sharma, Hans van Lint, Lóránt Tavasszy, Maaike Snelder
      Abstract: Transportation Research Record, Ahead of Print.
      Optimizing route choices for truck drivers is a key element in achieving reliable road freight operations. For commercial reasons, it is often difficult to collect freight activity data through traditional surveys. Automated vehicle identification (AVI) data on fixed locations (e.g., Bluetooth or camera) are low-cost alternatives that may have the potential to estimate route choice models. However, in cases where these AVI sensors are sparsely located, the resulting data lack actual route choices (or labels), which limits their application estimating route choice models. This paper overcomes this limitation with a new two-step approach based on fusing AVI and loop-detector data. First, a sparse Bluetooth data set is fused with travel times estimated from densely spaced loop-detector data. Second, the combined data set is fed into a bi-objective optimization method which simultaneously infers the actual route choices of truck drivers between an origin–destination pair and estimates the parameters of a route choice (discrete choice-based) model. We apply this approach to investigate the route choice behavior of truck drivers operating to and from the port of Rotterdam in the Netherlands. The proposed model can distinguish between peak and off-peak periods and identify different segments of truck drivers based on a latent classes choice analysis. Our results indicate the potential of traffic and logistics interventions in improving the route choices of truck drivers during peak hours. Overall, this paper demonstrates that it might be possible to estimate route choice characteristics from readily available data that can be retrieved from traffic management agencies.
      Citation: Transportation Research Record
      PubDate: 2022-06-01T11:51:05Z
      DOI: 10.1177/03611981221095089
       
  • Systemic Safety Analysis of Midblock Pedestrian Crashes in Massachusetts

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      Authors: Jeff Gooch, Ian Hamilton, Bonnie Polin, Riana Tanzen, Tal Cohen
      Abstract: Transportation Research Record, Ahead of Print.
      Pedestrians are vulnerable road users on Massachusetts roadways, particularly at midblock crossings. To develop safety improvement projects to address pedestrian safety issues, Massachusetts Department of Transportation (MassDOT) conducted a systemic safety analysis of severe midblock pedestrian crashes. The analysis incorporated crash, roadway, transit, census, and equity data to identify roadway segments that showed the higher probability for a severe pedestrian crash. Based on overrepresentation, principal arterials, minor arterials, and major collectors were identified as focus facility types. Binomial logit regression was used to identify risk factors for each focus facility type. Risk factors included number of lanes, traffic volume, population density, commute behaviors, employment density, and measures of equity. The authors found consistent risk factors across the three focus facility types. Ultimately, MassDOT will use these results to prioritize sites for midblock pedestrian safety systemic improvements.
      Citation: Transportation Research Record
      PubDate: 2022-06-01T11:47:23Z
      DOI: 10.1177/03611981221094566
       
  • Missing Pavement Performance Data Imputation Using Graph Neural Networks

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      Authors: Lu Gao, Ke Yu, Pan Lu
      Abstract: Transportation Research Record, Ahead of Print.
      Pavement condition data is important for providing information on the current state of the network and determining the needs of preventive maintenance or rehabilitation treatments. However, the condition data set is often incomplete for various reasons such as measurement errors and non-periodic inspection intervals. Missing data, especially when missing systematically, presents loss of information, reduces statistical power, and introduces biased assessment. Existing practices in pavement management systems (PMS) usually discard entire cases with missing data or impute it through data correlation. This paper proposes a graph-based deep learning framework, convolutional graph neural networks, to tackle the missing data problem in PMS. Unlike other variants of neural networks, the proposed approach is able to capture the spatio-temporal relationship in data and to learn and reconstruct the missing data by combining information among neighboring sections. In the case study, pavement condition data from 4,446 sections managed by Texas Department of Transportation were used. Experiments show that the proposed model was able to outperform standard machine learning models when imputing the missing data.
      Citation: Transportation Research Record
      PubDate: 2022-06-01T11:42:05Z
      DOI: 10.1177/03611981221095511
       
  • Rolling Stock Allocation and Timetabling for Urban Rail Transit Network
           with Multiple Depots

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      Authors: Fan Pu, Jiateng Yin, Yihui Wang, Shuai Su, Lixing Yang, Tao Tang
      Abstract: Transportation Research Record, Ahead of Print.
      Rolling stock management and train timetabling are two challenging but very related issues in urban rail systems. The former is to allocate a certain fleet of trains to each depot, and the latter determines the arrival and departure times of train services according to the available rolling stock at each depot. While most existing studies consider these two tasks for a single line, this study focuses on the integrated optimization of rolling stock allocation, train timetabling, and rolling stock circulation for a whole network, where each depot can serve multiple connected lines and the trains can change lines in one operational cycle (i.e., one day). A time-space network is constructed to model the rolling stock circulation among multiple lines and depots, and a novel integer linear programming model is proposed to jointly optimize the allocation of rolling stock and train timetables for the involved lines. The objective function maximizes the service quality provided to passengers with minimized rolling stock investment cost. Numerical experiments based on the real-world data of the Beijing rail transit network are conducted to validate the effectiveness of this approach. The results demonstrate that the proposed approach can reduce the fleet size of rolling stock by 5% while providing the same service quality to passengers.
      Citation: Transportation Research Record
      PubDate: 2022-06-01T11:34:25Z
      DOI: 10.1177/03611981221093323
       
  • Influence of Mode Use on Level of Satisfaction with Daily Travel Routine:
           A Focus on Automobile Driving in the United States

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      Authors: Tassio B. Magassy, Irfan Batur, Aupal Mondal, Katherine E. Asmussen, Sara Khoeini, Ram M. Pendyala, Chandra R. Bhat
      Abstract: Transportation Research Record, Ahead of Print.
      How does the extent of automobile use affect the level of satisfaction that people derive from their daily travel routine, after controlling for many other attributes including socio-economic and demographic characteristics, attitudinal factors, and lifestyle proclivities and preferences' This is the research question addressed by this paper. In this study, data collected from four automobile-dominated metropolitan regions in the United States (Phoenix, Austin, Atlanta, and Tampa) are used to assess the impact of the amount of driving that individuals undertake on the level of satisfaction that they derive from their daily travel routine. This research effort recognizes the presence of endogeneity when modeling multiple behavioral phenomena of interest and the role that latent attitudinal constructs reflecting lifestyle preferences play in shaping the association between behavioral mobility choices and degree of satisfaction. The model is estimated using the generalized heterogeneous data model (GHDM) methodology. Results show that latent attitudinal factors representing an environmentally friendly lifestyle, a proclivity toward car ownership and driving, and a desire to live close to transit and in diverse land use patterns affect the relative frequency of auto-driving mode use for non-commute trips and level of satisfaction with daily travel routine. Additionally, the amount of driving positively affects satisfaction with daily travel routine, implying that bringing about mode shifts toward more sustainable alternatives remains a formidable challenge—particularly in automobile-centric contexts.
      Citation: Transportation Research Record
      PubDate: 2022-05-31T09:43:19Z
      DOI: 10.1177/03611981221088199
       
  • Child Restraint Use and Seating Position of Child Passengers in Motor
           Vehicles and Their Correlations: Application of a Random-Effects Bivariate
           Probit Model

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      Authors: Meghna Chakraborty, Md Shakir Mahmud, Timothy J. Gates
      Abstract: Transportation Research Record, Ahead of Print.
      Motor vehicle crashes are a leading cause of death and injury for children aged under 8 years. In the U.S.A., while some states are showing increases in the proportion of child restraint device use, only around half of child passengers aged from 4 to 7 years are being properly restrained. This study was undertaken to identify the factors contributing to the proper child restraint use and child passenger’s seating position through the direct observation surveys of more than 10,000 child passengers in 2015 and 2018 in Michigan. A bivariate probit model with random effects was developed to identify simultaneously the contributing factors for the proper restraint use and seating position of child passengers, accounting for the unobserved heterogeneity in the data. The bivariate framework is able to account for the correlation of the two dependent variables in the study. The results show that the two dependent variables are positively correlated, and this correlation is strongly significant. The key factors simultaneously influencing proper child restraint use and appropriate seating position of the child passenger include the age of the child, the number of child passengers in the vehicle, driver belt use, driver gender, age, and race, vehicle type, stratum, weather, and the time of the day and week. However, factors such as county-specific population, income, and education, and the type of location did not have any significant association with either child restraint use or the seating position of the child passenger.
      Citation: Transportation Research Record
      PubDate: 2022-05-28T07:06:08Z
      DOI: 10.1177/03611981221095088
       
  • Modeling Users’ Adoption of Shared Autonomous Vehicles Employing
           Actual Ridership Experiences

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      Authors: Roya Etminani-Ghasrodashti, Ronik Ketankumar Patel, Sharareh Kermanshachi, Jay Michael Rosenberger, Ann Foss
      Abstract: Transportation Research Record, Ahead of Print.
      Despite the growing interest in implementing shared autonomous vehicles (SAVs) as a new mobility mode, there is still a lack of methodologies to unpack SAV adoption by individuals after experiencing self-driving vehicles. This study aimed to fill this gap by analyzing data collected from a users’ survey of a self-driving shuttle piloted downtown and on a university campus in Arlington, TX. Employing structural equation modeling, the hypothesized relationships between SAV adoption and key factors were tested. Data analyses indicated that individuals with limited access to a private vehicles, low-income people, young adults, university students, males, and Asians were more likely to ride this new service. Furthermore, results showed that SAV service attributes, including internal and external service performance and usual transportation mode, affected users’ willingness to continue using the service in the future. The study also highlighted the role of trip waiting time, -purpose, and -frequency on SAV adoption. Our model simultaneously considered usual transportation mode and trip frequency as factors that could mediate the role of vehicle ownership on SAV adoption. The results suggested that participants with greater access to a private vehicle were strongly interested in using private vehicles and less likely to use the ridesharing alternative, consequently they less frequently used the piloted SAV. The outcomes from this study are expected to inform planners with advanced knowledge about emerging technology to help them to adjust SAV policies before autonomous vehicle services are fully on the roads.
      Citation: Transportation Research Record
      PubDate: 2022-05-25T02:15:07Z
      DOI: 10.1177/03611981221093632
       
  • Data-Driven Approach to Weather-Responsive Speed Management of Road Tunnel
           Access Zones

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      Authors: Soyoung Jung, Xiao Qin
      Abstract: Transportation Research Record, Ahead of Print.
      In South Korea, one of the leading causes of motor vehicle crashes occurring at road tunnel entrances is speeding or failure to maintain a safe distance, especially during adverse weather conditions. The South Korean government released a strategic plan to address this issue through weather-responsive speed limit adjustments at tunnel entrances. This study aimed to assist the South Korean government’s plan with a data-driven safety approach. In particular, crash data from freeway tunnel access zones were augmented with real-time traffic speed and weather data, and standard binomial logit regression (BLR) with random forest (RF)-based variable selection was employed. The key variables contributing to crashes at freeway tunnel access zones during adverse weather conditions were identified as: speeding or failure to maintain a safe distance; no existence of a roadside fence; freeway sections with a distance of 100 to 250 m from the tunnel entrance; and interactions of traffic speed with wet pavement, average hourly rainfall of 6 h, visibility, and humidity preceding crash. The current standards for weather-responsive speed limit adjustment and appropriate deployment of variable message signs can be informed by the findings of this study.
      Citation: Transportation Research Record
      PubDate: 2022-05-24T09:56:18Z
      DOI: 10.1177/03611981221095749
       
  • Statewide Assessment of Balanced Mixture Design for New York State’s
           Asphalt Mixtures

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      Authors: Thomas Bennert, Edwin Haas, Edward Wass, Drew Tulanowski, Zoeb Zavery
      Abstract: Transportation Research Record, Ahead of Print.
      As state agencies want greater assurance that their asphalt materials will last longer, the inclusion of performance testing during mixture design and production has gained popularity. In particular, the concept of determining the asphalt content that optimizes asphalt mixture rutting and fatigue cracking resistance, called balanced mixture design (BMD), is being explored in the U.S. In this study, the New York State Department of Transportation (NYSDOT) orchestrated a statewide evaluation of their asphalt mixtures under the BMD concept. Eleven asphalt mixtures, representing a majority of what is utilized as surface courses on New York (NY) asphalt pavements, were first volumetrically verified and then evaluated using BMD to determine the range of asphalt content where rutting and fatigue cracking resistance optimization are achieved. Three laboratory rutting tests (asphalt pavement analyzer [APA], Hamburg wheel tracking [HWT], and high temperature indirect tensile strength [HT-IDT]), and three fatigue cracking tests (overlay tester, semi-circular bending [SCB] flexibility index, and indirect tensile asphalt cracking test [IDEAL-CT] index) were utilized during the performance testing. The results showed that 6 of the 11 volumetrically designed asphalt mixtures were under-asphalted with respect to achieving minimum fatigue cracking resistance based on the laboratory tests. None of the volumetrically designed asphalt mixtures were determined to have rutting issues. The addition of polymer modification in the asphalt binders was found to increase the range of asphalt contents achieving a balanced condition. The study also showed that, when appropriate performance criteria are selected, it is possible to utilize different test methods.
      Citation: Transportation Research Record
      PubDate: 2022-05-24T09:51:32Z
      DOI: 10.1177/03611981221092760
       
  • Procurement Benchmarks for Major Transportation Projects

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      Authors: Kunqi Zhang, Abdolmajid Erfani, Ousama Beydoun, Qingbin Cui
      Abstract: Transportation Research Record, Ahead of Print.
      The U.S. transportation industry has long called for a schedule and cost benchmark tool to assist project sponsors with developing project delivery plans benchmarked in reference to similar past projects across the nation. Such a benchmark tool has recently been developed in response to the industry demand and a mandate of the Fixing America’s Surface Transportation Act. The tool capitalized on the Information Source for Major Projects database, which adopted standard processes and uniform terminology for documenting critical milestones throughout the project lifecycle. Based on 137 major transportation projects, the benchmark model produces schedule benchmarks on environmental study, procurement, and implementation processes. Also, the benchmark tool recommends a cost benchmark based on the Federal Highway Administration’s standard. Users have the flexibility to define a benchmark level and a suite of project features including type, size, class of action required under the National Environmental Policy Act, and delivery method such as design-bid-build, design-build or public–private partnerships. Benchmark level is the percentage of projects that outperform the other projects with the same selected features. The tool promises immense potential for milestone planning and can provide insightful expectation of project milestones in support of delivery method selection. Included in the tool are benchmark charts, a handy reference from which schedule benchmarks can be read. This paper demonstrates the use of the tool in a case example.
      Citation: Transportation Research Record
      PubDate: 2022-05-24T09:46:52Z
      DOI: 10.1177/03611981221092722
       
  • Work Zone Crash Occurrence Prediction Based on Planning Stage Work Zone
           Configurations Using an Artificial Neural Network

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      Authors: Yang Cheng, Keshu Wu, Hanchu Li, Steven Parker, Bin Ran, David Noyce
      Abstract: Transportation Research Record, Ahead of Print.
      Work zones are essential to maintain and improve road infrastructure. However, work zones affect traffic safety, and crashes and fatalities associated with work zones in the U.S.A. have increased substantially. Most existing work zone crash studies are not able to support the improvement of work zone planning and configuration, despite providing insights about individual crash level attributes. This study proposes an artificial neural network-based approach to predict the crash occurrence in work zones using only work zone configurations and design parameters. The goal is to explore whether using simple work zone configuration features available at the planning stage as the input can achieve satisfactory work zone crash prediction. The performance of the proposed model is satisfactory and comparable with existing studies using more comprehensive features. The proposed approach, early in the work zone design and planning stage, can provide designers and decision-makers with quick work zone safety evaluation for design alternatives and suggest extra resources and attention needed.
      Citation: Transportation Research Record
      PubDate: 2022-05-24T09:42:12Z
      DOI: 10.1177/03611981221092716
       
  • Analysis of Road Transport Response to COVID-19 Pandemic in Nigeria and
           its Policy Implications

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      Authors: Donald Chiuba Okeke, Obiora Obasi, Maxwell Umunna Nwachukwu
      Abstract: Transportation Research Record, Ahead of Print.
      The COVID-19 pandemic presents a serious global health challenge to humanity in recent times. It has caused fundamental disruptions to the global transportation system, supply chains, and trade. The impact on the transport sector resulting from lockdowns has led to huge losses in revenue. At the moment there are limited studies of the road transport sector response to the COVID-19 pandemic. This paper fills this gap using Nigeria as a case study area. A mixed method involving both qualitative and quantitative research was employed. Principal Component Analysis and Multiple Criteria Analysis were used to analyze the data. The results suggest that road transport operators strongly (90.7%) believe that 51 adopted new technologies/innovations, processes, and procedures will keep them and passengers safe from the COVID-19 pandemic in Nigeria. A breakdown shows that observing the lockdown directive is perceived by road transport operators as the most effective response to the pandemic. The breakdown continues in descending order thus: COVID-19 safety protocols, environmental sanitation, and promotion of hygiene, information technology, facemask, and social distancing. Others are public enlightenment, palliative, inclusion, and mass media. This indicates that non-pharmaceutical measures are very effective in the fight against the pandemic. This finding leverages support for the application of non-pharmaceutical guidelines in containing the COVID-19 pandemic in Nigeria.
      Citation: Transportation Research Record
      PubDate: 2022-05-24T09:38:29Z
      DOI: 10.1177/03611981221092387
       
  • Evaluating the Impact of Urban Consolidation Center and Off-Hour
           Deliveries on Freight Flows to a Retail District Using Agent-Based
           Simulation

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      Authors: Rakhi Manohar Mepparambath, Lynette Cheah, P. Christopher Zegras, André Romano Alho, Takanori Sakai
      Abstract: Transportation Research Record, Ahead of Print.
      With rapid ongoing urbanization, cities across the world face a multitude of challenges in urban logistics. Delivery of goods to retail districts is particularly challenging as these places are typically located in congested urban centers. In response, policy makers have explored various freight management initiatives, including urban consolidation centers (UCC) and off-hour deliveries (OHD). This study examines the impact of these initiatives on freight flows to a retail district in Singapore. The study approach pairs empirical behavioral models and an agent-based simulation. First, using results from a stated preference survey, the choice behavior of two relevant actors—establishments that ship goods and establishments that receive goods within a retail district—and their likelihood of participating in UCC or OHD are analyzed. Then, the resulting behavioral models are incorporated into a city-scale agent-based simulator to evaluate the impact of these initiatives on freight flows, tracking multiple logistics-related performance indicators. The results show that the likelihood of participating in UCC and OHD declines when multiple actors are involved in the participation decision. Both UCC and OHD have the potential to reduce freight traffic and parking demand, although in different ways. For UCC, a minimum level of participation must be achieved to guarantee increase in vehicle load factors. OHD decreases load factors as well as the required number of dedicated trips to the retail district.
      Citation: Transportation Research Record
      PubDate: 2022-05-24T09:34:12Z
      DOI: 10.1177/03611981221092385
       
  • Data-Driven Computation of State-Dependent Passenger Car Equivalency for
           Multiple Truck Lengths

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      Authors: Eren Yuksel, Robert L. Bertini, Xiaopeng (Shaw) Li, Brian Staes, Seckin Ozkul
      Abstract: Transportation Research Record, Ahead of Print.
      Passenger car equivalency (PCE) has been used for decades to convert mixed vehicle traffic into equivalent pure passenger car traffic streams for transportation planning, design, and operational analysis purposes. The term PCE was defined by the Highway Capacity Manual (HCM) in 1965 as an adjustment factor, and many approaches have continued to be developed for refining PCE values for different types of freeway geometry and vehicle distributions since then. This paper proposes an improved data-driven state-dependent passenger car equivalency (PCE–SD) approach, initially for level terrain basic freeway segments that consider average vehicle lengths for different types of vehicles. The term “state-dependent” refers to the space headway ratio at the same speed ranges between long vehicles (trucks), that fall into the same clustered category, and passenger cars. The relatively unique data stream used in this study comes from the Portland Oregon Regional Transportation Archive Listing (PORTAL) online datahub. This rich continuous data stream provides valuable information about traffic-related data at a 20-s aggregation level. Most importantly for this effort, ranges of categorical vehicle lengths are also available. According to analysis results, PCE–SD values estimate the actual passenger car distribution at different speeds and levels of operational performance (levels of service) more accurately compared with the HCM-6 PCEs on level terrain basic freeway segments. The authors propose that a state-dependent passenger car equivalency approach bridges the conversion gap from different types of trucks to passenger vehicles and could be used as an improved supplementary methodology.
      Citation: Transportation Research Record
      PubDate: 2022-05-24T09:28:41Z
      DOI: 10.1177/03611981221092008
       
  • Automated Vehicles: Use, Share, Own' Young Adults’ Perceptions
           of Automated Vehicles

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      Authors: Hannah Bagli, Elizabeth Shay, Tabitha Combs
      Abstract: Transportation Research Record, Ahead of Print.
      Automated Vehicles (AVs) will change the transportation landscape in still-uncertain ways. The timeline for this change depends not just on the pace of technological advancement, but also on public attitudes about AVs. These attitudes include perceptions of safety and tolerance of new vehicle ownership structures that will likely emerge when and if fully self-driving models are available. This study aims to determine the extent to which young people are open to using AVs and forgoing ownership of conventional personal vehicles in favor of AV-based shared mobility. With the potential for widespread AV deployment in the near term, the perspectives of this age group are important for understanding the impacts of AVs on the mobility landscape. An online survey was distributed through professional networks across the country in early 2020 to gauge comfort levels in riding in AVs, relying on shared mobility, and owning an AV. Univariate and bivariate chi-square tests were performed to test the correlation between explanatory variables and perceptions of AVs. The responses revealed ambivalence toward AVs. Significant relationships indicate that gender identity and urbanicity matter when it comes to willingness to use AVs and shared mobility. Results also show that young adults may not be as ready for AVs as some have hypothesized. The results of this study help address gaps in AV perception research and gauge current attitudes of young adults toward a future of transportation that includes connected and automated vehicles.
      Citation: Transportation Research Record
      PubDate: 2022-05-24T02:19:00Z
      DOI: 10.1177/03611981221092382
       
  • Classification of Driver Cognitive Load: Exploring the Benefits of Fusing
           Eye-Tracking and Physiological Measures

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      Authors: Dengbo He, Ziquan Wang, Elias B. Khalil, Birsen Donmez, Guangkai Qiao, Shekhar Kumar
      Abstract: Transportation Research Record, Ahead of Print.
      In-vehicle infotainment systems can increase cognitive load and impair driving performance. These effects can be alleviated through interfaces that can assess cognitive load and adapt accordingly. Eye-tracking and physiological measures that are sensitive to cognitive load, such as pupil diameter, gaze dispersion, heart rate (HR), and galvanic skin response (GSR), can enable cognitive load estimation. The advancement in cost-effective and nonintrusive sensors in wearable devices provides an opportunity to enhance driver state detection by fusing eye-tracking and physiological measures. As a preliminary investigation of the added benefits of utilizing physiological data along with eye-tracking data in driver cognitive load detection, this paper explores the performance of several machine learning models in classifying three levels of cognitive load imposed on 33 drivers in a driving simulator study: no external load, lower difficulty 1-back task, and higher difficulty 2-back task. We built five machine learning models, including k-nearest neighbor, support vector machine, feedforward neural network, recurrent neural network, and random forest (RF) on (1) eye-tracking data only, (2) HR and GSR, (3) eye-tracking and HR, (4) eye-tracking and GSR, and (5) eye-tracking, HR, and GSR. Although physiological data provided 1%–15% lower classification accuracies compared with eye-tracking data, adding physiological data to eye-tracking data increased model accuracies, with an RF classifier achieving 97.8% accuracy. GSR led to a larger boost in accuracy (29.3%) over HR (17.9%), with the combination of the two factors boosting accuracy by 34.5%. Overall, utilizing both physiological and eye-tracking measures shows promise for driver state detection applications.
      Citation: Transportation Research Record
      PubDate: 2022-05-23T11:37:02Z
      DOI: 10.1177/03611981221090937
       
  • Dynamic Routing Algorithm for Hazmat Transportation Problems

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      Authors: Ta-Yin Hu, Yu-Cheng Hsu, Tsai-Yun Liao
      Abstract: Transportation Research Record, Ahead of Print.
      After a series of gas pipeline explosions in Kaohsiung City, Taiwan, in 2014, the Environmental Protection Administration (EPA) issued regulations in 2017 requiring all chemical tank trucks to be equipped with GPS for real-time monitoring and control. Hazmat transportation problems, along with solution algorithms and applications, have been studied extensively. However, most of the research has focused on the route planning level. Dynamic characteristics should be incorporated to reflect possible dynamic traffic situations with more advanced information and communication capabilities for chemical tank trucks. This research formulates a bi-objective dynamic model and proposes a solution algorithm based on a genetic algorithm (GA) for dynamic hazmat route optimization. A dynamic bi-objective model, including transportation cost and risk, is developed to reflect time-varying traffic conditions. Dynamic traffic characteristics are reflected through traffic volume and travel time, simulated from simulation models. Numerical experiments are conducted in the Kaohsiung City network. The results show that dynamic routes for hazmat transportation vary with respect to traffic flow conditions. The discussions of this research are expected to provide some insights into policy implications.
      Citation: Transportation Research Record
      PubDate: 2022-05-23T07:15:45Z
      DOI: 10.1177/03611981221092002
       
  • Convolutional Neural Network with Attention Module for Identification of
           Tunnel Seepage

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      Authors: Qian Chen, Chuanguo Xiong, Weishan Lv, Ben Shen, Baoshan Zeng, Jinming Li, Chenzefang Feng, Zhou Hu, Fulong Zhu
      Abstract: Transportation Research Record, Ahead of Print.
      As tunnel construction proceeds ever more rapidly, the efficiency of seepage detection by engineers with expert knowledge is facing unprecedented challenges. Moreover, it suffers from strong subjectivity. In recent years, deep learning, as an algorithm of machine learning, has achieved state-of-the-art performance in pattern recognition. In this paper, we address such a problem by building convolutional neural networks that operate on conventional graphics processing units. Within the project, the data is obtained by an infrared thermal imager since there exist different characteristics of temperature between the area of seepage and non-seepage. Considering the difficulty of collecting many images, generative adversarial nets and other data augmentation skills are applicable to enlarge data sets. We design several novel architectures where the attention mechanism is plugged into various traditional models, considered as VGG16 network with Attention Module and RestNet34 with Attention Module, and the overall identification accuracy achieved is more than 97%. The codes of this project can be found at https://github.com/Scotter-Qian/cnn.
      Citation: Transportation Research Record
      PubDate: 2022-05-23T07:10:22Z
      DOI: 10.1177/03611981221091774
       
  • Performance Evaluation and Prediction of Preservation Asphalt Overlay in
           Louisiana

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      Authors: Zhaoxing Xie, Zhong Wu, Farzana Moon, Moinul Mahdi, Yilong Liu
      Abstract: Transportation Research Record, Ahead of Print.
      The Louisiana Department of Transportation and Development (LaDOTD) has been using thin asphalt overlay (2 in.) as a preservation technique for asphalt-surface pavements. Although LaDOTD has specified the triggers for its application, it was not always applied on the recommended timing. It is unclear how the application timing affects the overlay performance. Additionally, no studies have been conducted to determine optimal application timing for the overlay and predict its performance using the available tools such as AASHTOWare Pavement Mechanistic-empirical design (Pavement ME) software. The objectives of the study are (1) to evaluate field performance of the preservation asphalt overlay and develop performance prediction models, (2) to determine optimal application timing for the overlay, and (3) to investigate if Pavement ME models are able to predict performance of the overlay by modifying model coefficients. To achieve the objectives, 33 preservation asphalt overlay projects were selected, and their performance was evaluated and predicted, then the optimal application timing was investigated based on the benefit and cost analysis. The results indicate that 58% of the preservation asphalt overlays had 10–20 years’ service life, and 42% had 7–10 years’ service life in relation to Pavement Condition Index threshold of 70. Additionally, good precondition or flexible base (asphalt concrete or unbounded base) can result in a longer service life in the overlay. It is also found that an average value of optimal timing of the next overlay application is the 9th year after construction. Finally, the rehabilitation models of asphalt overlay in Pavement ME software could be used for preservation asphalt overlay by modifying model coefficients.
      Citation: Transportation Research Record
      PubDate: 2022-05-23T07:05:23Z
      DOI: 10.1177/03611981221091563
       
  • Calibration of a Mechanistic-Empirical Cracking Model Using Network-Level
           Field Data

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      Authors: Rongzong Wu, John Harvey, Jeremy Lea, David Jones, Stephanus Louw, Angel Mateos, Noe Hernandez-Fernandez, Raghubar Shrestha, Joe Holland
      Abstract: Transportation Research Record, Ahead of Print.
      At the core of a mechanistic-empirical (M-E) pavement design method is a collection of performance models that each predicts the development of a specific pavement distress, such as fatigue cracking and surface rutting. Each model has both mechanistic and empirical parts. The empirical parts need to be calibrated to remove bias and increase prediction accuracy. This process has traditionally been conducted with small numbers of field sections for which materials may or may not have been sampled and tested. This paper presents a new calibration approach that uses network-level field data and statewide distributions of material properties, without having to sample and test every individual calibration section. The calibration of the fatigue and reflection cracking models for CalME, the M-E design software developed for the California Department of Transportation, is used as an example to illustrate the new approach. The new approach works by correlating the statistical distributions of M-E design inputs with the statistical distribution of pavement performance, both at the network level. The uncertainties affecting pavement performance are divided into those specific to a given project (within-project variability) and those that vary between projects (between-project variability). This distinction allows a clear definition of design reliability. The results showed that the new approach can overcome some of the network-level data limitations and provides a reasonable calibration ready for routine pavement design.
      Citation: Transportation Research Record
      PubDate: 2022-05-23T07:05:06Z
      DOI: 10.1177/03611981221091561
       
  • Injury Severity Analysis for Large Truck-Involved Crashes: Accounting for
           Heterogeneity

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      Authors: Ghazaleh Azimi, Alireza Rahimi, Hamidreza Asgari, Xia Jin
      Abstract: Transportation Research Record, Ahead of Print.
      This study explores the crash injury severity of large truck-involved crashes, where the truck driver was identified as the at-fault driver. The paper focuses on vehicle-in-motion crashes that occurred on Florida’s state highways between 2007 and 2016. A random parameter ordered logit (RPOL) model was developed to identify random parameters and interaction effects. Results indicated that not using restraint systems, running a red light, wrong-way driving, failing to yield the right of way, tire or brake defects, and dark conditions had positive associations with higher levels of crash injury severity. The random variables—straight alignment, paved shoulders, and unpaved shoulders—showed significant random effects among the observations. For straight alignment, running red lights, following too closely, vision obstruction caused by fixed objects, and vision obstruction caused by fog were the sources of heterogeneity. Unpaved shoulders, running red lights, wrong-way driving, and the presence of parked or stopped vehicles were found as interaction effects. Results showed that accounting for heterogeneity and interaction effects significantly improved the goodness of fit of the model. This study provides more comprehensive knowledge of the influencing factors of large truck crashes by considering the role of heterogeneity and its potential sources in crash injury severity.
      Citation: Transportation Research Record
      PubDate: 2022-05-23T07:04:54Z
      DOI: 10.1177/03611981221091562
       
  • Developing an Optimal Peer-to-Peer Ride-Matching Problem Algorithm with
           Ride Transfers

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      Authors: Amirreza Nickkar, Young-Jae Lee, Mana Meskar
      Abstract: Transportation Research Record, Ahead of Print.
      Thanks to recent developments in ride-hailing transit services throughout the world, the peer-to-peer (P2P) ride-matching problem has been actively considered in academia in recent years. P2P ride-matching not only reduces travel costs for riders but also benefits drivers by saving them money in exchange for their additional travel time. However, assigning riders to drivers in an efficient way is a complex problem that requires focusing on maximizing the benefits for both riders and drivers. This study aims to formulate a multi-driver multi-rider (MDMR) P2P ride-matching problem, based on rational preferences and cost allocation for both driver and rider, which also allows riders to transfer between multiple drivers for their travels if needed. Tabu Search (TS) for system-optimal ride-matching and a Greedy Matching (GM) algorithm for stable ride-matching were developed to solve ride-matching cases. The results show that the developed algorithm can successfully solve the proposed P2P MDMR ride-matching problem. MDMR P2P ride-matching can be used in areas where not much demand for ride-sharing exists, or for long-distance travel. Also it can be applied to designs for a more efficient on-demand transit network which can allow for transfers between routes. Moreover, the comparison of results between two implemented approaches shows that system-optimal centralized ride-matching can bring more cost savings for all participants in the system, although it may not always be stable when riders and drivers can choose their ride-matching for their own maximum benefit.
      Citation: Transportation Research Record
      PubDate: 2022-05-23T07:04:54Z
      DOI: 10.1177/03611981221091759
       
  • Reliability-Based Assessment of Concrete Decks Designed Using Approximate
           Method at the Strength I Limit State

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      Authors: Chan Yang, Peng Lou, Hani Nassif
      Abstract: Transportation Research Record, Ahead of Print.
      The Approximate Method coupled with the AASHTO Load and Resistance Factor Design (LRFD) Bridge Design Specifications (BDS) is applied for designing reinforced concrete bridge decks. Although the LRFD BDS has an intrinsic design return period of 75 years and a target reliability index of 3.5 at the Strength I Limit State, many concrete bridge decks exhibit much shorter service life. Besides the limitations of the crack control limit state at service, the inadequate nominal resistance at the Strength Limit State could contribute to the shortened service life. This paper presents a reliability-based assessment of the current concrete deck design provisions by utilizing actual truck load spectra collected from the national weigh-in-motion (WIM) data. Axle groups, including single axles, tandem axles, and tridem axles, were identified from the WIM data. The moment effects are obtained from influence surface analysis, formulating the live load statistics, particularly for the decks that are supported by girders. It was found that the current design load is not able to represent and envelop the actual traffic load. Additionally, the reliability indices are calculated for a series of reinforced concrete decks on account of both bending moment capacity and arching action moment capacity. The arching action was found to greatly enhance the reliability index for the positive moment region, providing satisfactory reliability indices. The negative moment region may or may not meet the target reliability index depending on the design criteria.
      Citation: Transportation Research Record
      PubDate: 2022-05-23T06:43:20Z
      DOI: 10.1177/03611981221090942
       
  • Autonomous Vehicles in Urban Networks: A Simulation-Based Assessment

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      Authors: Athina Tympakianaki, Leyre Nogues, Jordi Casas, Mark Brackstone, Maria G. Oikonomou, Eleni I. Vlahogianni, Tamara Djukic, George Yannis
      Abstract: Transportation Research Record, Ahead of Print.
      The paper proposes a general framework for the assessment of the impacts of the introduction of Connected and Automated Transport Systems (CATS) on traffic. The main objective is to address the question of scalability and transferability of the identified impacts of Autonomous Vehicles (AVs) in particular, focusing on network performance of urban areas. A combination of microscopic and macroscopic simulations as well as statistical methods are applied. Microscopic simulation is conducted to measure the changes in network capacities by utilizing the concept of the Macroscopic Fundamental Diagram (MFD), under different AV penetration rates. The resulting capacities are used to estimate the effects on the Passenger Car Units (PCU) under different AV penetration rates and derive functional relationships, which are further introduced to travel demand models to forecast the macroscopic impacts on network performance. The results indicate a positive impact in relation to capacity changes resulting from the presence of AVs which vary with penetration rate. Analysis of three different urban networks, Barcelona, Bilbao (Spain), and Athens (Greece), reveals consistent trends. However, notable differences are observed on the estimated PCUs for Athens, potentially because of the different mixed-traffic composition. Further exploration of the critical AV modeling specifications and network characteristics is therefore required for deriving transferable PCU functional relationships across networks. Nevertheless, the static assignment results verify the expected trends in network performance impacts in relation to the applied PCU relationships. Finally, the transferability of the proposed methodology across networks is demonstrated.
      Citation: Transportation Research Record
      PubDate: 2022-05-23T06:33:45Z
      DOI: 10.1177/03611981221090507
       
  • Understanding the Influence of Pavement Conditions on Cyclists’
           Perception of Safety and Comfort Using Surveys and Eye Tracking

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      Authors: April Gadsby, James Tsai, Kari Watkins
      Abstract: Transportation Research Record, Ahead of Print.
      Although infrequently included in studies of cyclists’ perceived safety, pavement condition has an influence on cyclists’ stress and related perceptions of safety. Few studies investigating the influence of pavement condition on cyclists’ perceived safety have developed actionable information for industry professionals. This paper aims to fill that gap by identifying which forms of pavement distress most influence cyclists’ perceived safety and comfort. The study used a combination of online surveys and field experiments. The 181 complete responses to the online survey showed potholes were the most important pavement distress for perceived safety and comfort. Eye-tracking data from 17 field participants were collected and analyzed for the following: whether participants fixated on the distresses; when; and for how long. These results showed that unevenness attracted the most fixations for the longest duration. In mixed traffic scenarios, participants tended to fixate less frequently compared with the separated facility, suggesting a potential safety concern. These findings are compiled into the following recommendations for cyclist-focused maintenance practices: (a) the need to focus on perceived safety, and on the extent, avoidability, and visibility of pavement distresses; (b) shift cyclists to separated facilities; (c) prioritize mixed facilities for routine maintenance; (d) prioritize bicycle lanes for high-cost repairs; (e) shift street-sweeping operations to bicycle lanes; (f) develop new deterioration models and fill mix designs; and (g) determine the appropriate treatment, maintenance activity, and timing. These recommendations can be used by asset management planners and maintenance personnel to improve the perceived safety and comfort of their cycle network.
      Citation: Transportation Research Record
      PubDate: 2022-05-21T07:37:19Z
      DOI: 10.1177/03611981221090936
       
  • Development of a Simulation-Based Approach for Cold In-Place Recycled
           Pavement Moisture-Content Prediction Using Ground-Penetrating Radar

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      Authors: Qingqing Cao, Lama Abufares, Imad Al-Qadi
      Abstract: Transportation Research Record, Ahead of Print.
      Ground-penetrating radar (GPR) recently has been used for quality control and quality assurance of the asphalt concrete (AC) pavement-construction process. The objective of this study was to investigate the feasibility of estimating, by using GPR, the moisture content in AC pavement. This application is particularly important for emulsion-stabilized cold in-place recycling (CIR) and cold central-plant recycling (CCPR), where monitoring the moisture content is necessary for deciding the timing of opening the road to traffic, overlay placement, or both. Four field tests were performed using GPR on CIR- or CCPR-treated AC pavement. A numerical simulation model of AC pavement with internal moisture was generated using the information from mix design, and virtual GPR tests were performed using the finite-difference time-domain (FDTD) method. After calibration, a moisture-prediction formula derived from the simulation model was used to correlate the dielectric constant predicted by GPR to the moisture content within cold recycled layers. The GPR signal was “denoised” by improving its stability and mitigating the measured-height mismatch. The in-situ moisture content was predicted using the proposed method and compared with field-collected samples. Results showed that the proposed method is effective in estimating CIR- and CCPR-layer moisture content. The variation of dielectric constants in field tests is also discussed. A testing protocol for predicting moisture content using GPR is suggested for CIR and CCPR pavement.
      Citation: Transportation Research Record
      PubDate: 2022-05-21T07:31:18Z
      DOI: 10.1177/03611981221090933
       
  • High Volume Freeway Travel Time Reliability and the COVID-19 Pandemic

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      Authors: Ernest Tufuor, Laurence Rilett
      Abstract: Transportation Research Record, Ahead of Print.
      This paper examines the effect of the COVID-19 pandemic on travel time reliability (TTR) performance on two high traffic volume freeway corridors (I-90 and I-405) in the U.S.A. Specifically, the travel time distributions (TTDs) during and before the pandemic are compared. The paper also examines which TTR metrics best capture the effect of the pandemic on reliability performance. There were statistically significant differences, at the 95% confidence level, between TTD in 2020 and corresponding TTDs in 2018 and 2019. Not surprisingly, all measures of central tendency and all measures of dispersions were reduced during the pandemic. Consequently, it was concluded that TTR performance improved during the pandemic regardless of what TTR definition was used. Travel time index (TTI), planning time index (PTI), and the level of travel time reliability (LOTTR) metrics improved during the pandemic, albeit at different rates. In contrast, the buffer index and coefficient of variation increased. In other words, whether an analyst would identify that TTR improved or decreased during the pandemic, and by how much, would be a function of which TTR metric was applied. Not surprisingly, the more congested the roadway section, the greater the impact the pandemic-related interventions had on TTR. It was found that, practically speaking, there are no differences in TTI, PTI, or LOTTR values when TTDs are formulated using a 5 min or 15 min aggregation interval. It was concluded that analysts need to have a deep understanding of the underlying TTD and the various TTR definitions when evaluating changes in freeway systems’ TTR.
      Citation: Transportation Research Record
      PubDate: 2022-05-21T07:25:20Z
      DOI: 10.1177/03611981221090929
       
  • Twenty-Five Years of Rubber Tire Wheel Tracking of Asphalt Pavements in a
           Laboratory

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      Authors: Ben C. Cox, Ashley S. Carey, Jessica V. Lewis, Isaac L. Howard
      Abstract: Transportation Research Record, Ahead of Print.
      This paper assesses the state-of-the-art for rubber tire wheel tracking of asphalt mixtures in a laboratory setting with emphasis on differentiating moisture damage from rutting. This assessment made use of a comprehensive literature review and roughly 300 experiments conducted over several years with the second generation of the Purdue Laboratory Wheel Tracker (PURWheel). The literature review revealed that direct separation of rutting from moisture damage with physical measurements taken with a rubber tire under otherwise identical conditions is not common practice. Collective analysis of these roughly 300 experiments revealed that second-generation PURWheel protocols offer two specific contributions to the asphalt mixture testing community: (1) a pneumatic rubber tire is used, which is most representative of vehicle traffic; and (2) the effects of moisture damage can be decoupled from rutting by testing under both wet and dry conditions where all other parameters are constant. The analysis was performed on data collected for other purposes, but the data did provide seven manners to evaluate moisture damage and three manners to evaluate variability in the context of standardizing protocols. These 10 evaluations clearly demonstrated the potential of rubber tire wheel tracking to improve characterization of asphalt mixtures beyond what has occurred to date. This paper works toward standardization of protocols for rubber tire wheel tracking in wet and dry conditions, and some discussion is provided on the status and needed advancements toward this eventual goal.
      Citation: Transportation Research Record
      PubDate: 2022-05-20T06:09:13Z
      DOI: 10.1177/03611981221091558
       
  • Guidance Surface to Help Vision-Disabled Pedestrians Locate Crosswalks and
           Align to Cross

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      Authors: Billie Louise Bentzen, Alan C. Scott, Janet M. Barlow, Robert Wall Emerson, Jennifer Graham
      Abstract: Transportation Research Record, Ahead of Print.
      Raised-bar guidance surfaces (GSs) are used internationally to help wayfinding by vision-disabled pedestrians, but they are little used in the United States. However, difficulties experienced by vision-disabled pedestrians in locating crosswalks and aligning to cross have been documented, and the installation of GSs with bars perpendicular to the crossing direction has been shown to improve locating the crosswalk and aligning to cross at noncorner crossings. The present research investigated the effect, for a total of 68 participants, of a raised-bar GS on locating crosswalks and aligning to cross at (primarily) corner crossings in three cities. Using 2- × 2-ft raised-bar GSs with bars oriented perpendicular to the crossing direction at corner crossings, and a 2-ft wide strip of GSs extending across the sidewalk at noncorner crossings, significant improvements in the accuracy of crossing starting position and alignment were observed. Accuracy in locating the crosswalk was quite good at corner crossings, and was not improved by the GS. Installation of a raised-bar GS with bars perpendicular to the crossing direction is recommended to help vision-disabled pedestrians align for crossing. At corner crossings, a 2- × 2-ft GS located beside the detectable warning surface at the bottom of curb ramps, on the side farthest from the intersection, is recommended. At noncorner crossings, a 2-ft wide strip of GS extending all the way across the sidewalk, with the bars oriented perpendicular to the crossing direction, is recommended.
      Citation: Transportation Research Record
      PubDate: 2022-05-20T06:07:13Z
      DOI: 10.1177/03611981221090934
       
  • Ten Takeaways from the COVID-19 Pandemic for Transportation Planners

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      Authors: Karl E. Kim
      Abstract: Transportation Research Record, Ahead of Print.
      The COVID-19 pandemic has created significant challenges but also unprecedented opportunities for transportation researchers and practitioners. In this article, the major lessons and gaps in knowledge for those working in the transportation sector are identified, including the following: (1) integration between public health and transportation; (2) technology to support contact tracing and tracking of travelers; (3) focus on vulnerable, at-risk operators, patrons, and underserved members of society; (4) re-engineering of travel demand models to support social distancing, quarantine, and public health interventions; (5) challenges with Big Data and information technologies; (6) trust relationships between the general public, government, private sector, and others in disaster management; (7) conflict management during disasters; (8) complexities of transdisciplinary knowledge and engagement; (9) demands for training and education; and (10) transformative change to support community resilience. With a focus on transportation planning and community resilience, the lessons from the pandemic need to be shared and customized for different systems, services, modalities, and users. While many of the interventions during the pandemic have been based on public health, the management, response, recovery, adaptation, and transformation of transportation systems resulting from the crisis require multi-disciplinary, multi-jurisdictional communications and coordination, and resource sharing. Further research to support knowledge to action is needed.
      Citation: Transportation Research Record
      PubDate: 2022-05-20T06:05:33Z
      DOI: 10.1177/03611981221090515
       
  • Traffic Data and Summary Statistics Available through the Long-Term
           Pavement Performance Program for Pavement Modeling and Beyond

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      Authors: Olga I. Selezneva, Mark Hallenbeck, Debbie Walker
      Abstract: Transportation Research Record, Ahead of Print.
      This paper synthesizes traffic data and statistical parameters available through the Long-Term Pavement Performance Program (LTPP), provides recommendations to pavement engineers and researchers about the traffic parameters most suitable for different pavement analyses, and identifies LTPP database tables containing such parameters. The paper also contains information about LTPP traffic data collection methods and recommendations for assessing the rationality of truck weight data collected by weigh-in-motion (WIM) equipment. In summary, this paper was developed to highlight the wealth of truck traffic data available through LTPP and to serve as a resource document for pavement researchers, designers, and transportation planning professionals interested in LTPP truck traffic data and summary parameters characterizing truck traffic.
      Citation: Transportation Research Record
      PubDate: 2022-05-20T06:03:51Z
      DOI: 10.1177/03611981221089943
       
  • Urban Railway System Route Selection in Turkey Based on Socio-Economic and
           Technical Criteria Using the Analytical Hierarchy Process

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      Authors: Aslan İnan, Huzeyfe Kara
      Abstract: Transportation Research Record, Ahead of Print.
      With the increased importance of energy all over the world, new energy sources are needed to meet the energy demand. However, the solution to energy demand is not only finding new energy resources but also using currently consumed energy efficiently. Accordingly, decreasing the energy consumption in urban electric railway transport has become an important issue. Investment in urban railway transport is increasing continually because it is more economical, safe, and sustainable than other modes in local transportation. For new investments related to urban railway transport, decision-makers generally make an assessment that will include economic, demographic, and environmental impacts. In this study, a comprehensive top-down decision-making system for urban railway route selection was engineered by taking into account socio-economic criteria as well as technical criteria. In the context of surveys conducted with experts in the choice of railway system routing, five socio-economic criteria (passenger potential, construction cost, integration-access, zoning-ownership, travel time) and five technical criteria (vehicle energy consumption, regenerative energy, traffic operations, power supply system, efficient driving techniques) were determined. In the analysis, the analytical hierarchy process (AHP) method, one of the multi-criteria decision-making methods, was used to determine the best route among alternative routes based on all criteria.
      Citation: Transportation Research Record
      PubDate: 2022-05-19T09:39:18Z
      DOI: 10.1177/03611981221090513
       
  • Teen Driver Distractions and Parental Norms

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      Authors: Mehdi Hoseinzadeh Nooshabadi, Holland Vasquez, Maryam Merrikhpour, Birsen Donmez
      Abstract: Transportation Research Record, Ahead of Print.
      Research related to parental norms on teen driver distractions is limited, although distracted driving is a serious concern for teens. This paper investigates whether teens’ perception of their parent’s engagement in and approval of distractions is different to what their parent reports, and whether any discrepancy relates to teens’ self-reported distraction engagement frequency. It also investigates whether there are discrepancies between the parents’ perception of their teen’s distraction engagement frequency and the teen’s self-report. A distinction is made between legal and illegal distractions as drivers may build stronger norms around illegal distractions. Analyses were conducted on data from 63 teen–parent dyads from Ontario, Canada, who completed an online survey, including self-reported engagement in 16 distractions and related descriptive (what parents/teens do) and injunctive (what parents approve/disapprove) norms. Dyads were divided into two groups: higher-engagers (n = 27) and lower-engagers (n = 36) based on teens’ self-reported engagement frequency. Higher-engagers reported engaging in both distraction types (legal and illegal) more often than their parent did; there was no difference between lower-engagers and their parent. Higher-engagers’ perception of their parent’s engagement in and approval of legal distractions was higher than their parent’s self-report, while these parents perceived their teen’s engagement in both distraction types to be lower compared with the teen’s self-report. The only discrepancy observed for lower-engagers was that teens’ perception of their parent’s approval of legal distractions was higher than parents’ self-reports. Our findings suggest that misperceptions may exist for teens who engage more frequently in distractions and for their parents, who may benefit from relevant interventions.
      Citation: Transportation Research Record
      PubDate: 2022-05-19T09:37:18Z
      DOI: 10.1177/03611981221090505
       
  • Current Practices and Potential Rider Benefits of Fare Capping Policies in
           the U.S.A.

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      Authors: Ashley Hightower, Abubakr Ziedan, Cassidy Crossland, Candace Brakewood
      Abstract: Transportation Research Record, Ahead of Print.
      Fare capping, a policy in which a transit agency caps the maximum amount a rider pays over a given period, has emerged as a relatively new innovation in public transit fare policy. This research aims to synthesize fare capping policies and to explore the benefits that riders could receive from fare capping. This study applied a multiple case study method to explore fare capping policies at the 101 largest transit agencies in the U.S.A. At least 21 of those 101 agencies were found to have fare capping policies. Of those 21 agencies, 20 used daily fare caps, four used weekly fare caps, and 14 used monthly fare caps. The number of one-way regular fare trips needed to reach the daily, weekly, and/or monthly cap was determined for each agency. Rider discounts for each fare capping period were then calculated. This study also discussed some innovative fare capping policies like “nested” fare capping, which refers to fare caps within fare caps, as well as capping for reduced fare policies. These unique policies could help to address some of the most pressing challenges that face the transit industry in promoting equity for vulnerable groups such as low-income, elderly, and disabled riders, and incentivizing riders to return to transit post-COVID. The findings of this study could inform transit agencies that are planning or considering the implementation of fare capping policies, a trend which has grown rapidly in the transit industry.
      Citation: Transportation Research Record
      PubDate: 2022-05-19T09:35:58Z
      DOI: 10.1177/03611981221089572
       
  • Feasibility of Bridge Deicing Using Geothermal Energy Piles in Different
           U.S. Climates

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      Authors: Suguang Xiao, Muhannad T. Suleiman, Neti Sudhakar, Clay J. Naito, Guozhu Zhang
      Abstract: Transportation Research Record, Ahead of Print.
      Geothermal energy piles are an environmentally friendly energy source and an innovative approach to melt snow on the bridge surface and minimize or eliminate the use of deicing salt. However, the application potential of energy piles for bridge deicing or snow melting has not been fully explored for different climates. In this study, the feasibility of using energy piles for bridge deicing in eight cities of the United States was investigated. Temperature response function (G function) method was validated and used to estimate the extracted heat from energy piles installed in the soils with different thermal properties, which was used to heat the bridge deck during snowing. The results of numerical simulation and statistical analysis confirm that the performance of the geothermal deicing system depends on the weather conditions during snowing and thermal properties of soils. The coverage rate of the geothermal system (percentage of snowing time that the geothermal deicing system can keep the bridge surface above 0°C) increases with the increasing air temperature and thermal diffusivities of soils, and decreases with the increasing precipitation rate and wind speed. This deicing method is promising in cities with higher average air temperature and low precipitation rate during snowing.
      Citation: Transportation Research Record
      PubDate: 2022-05-19T09:31:38Z
      DOI: 10.1177/03611981221088212
       
  • Optimization of Dynamic Speed-Homogeneous Space Using Location-Based
           Vehicle Data

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      Authors: Kyusoo Chong, Young-in Lee
      Abstract: Transportation Research Record, Ahead of Print.
      Road extent compared with the number of automobiles registered in South Korea is the lowest among OECD (Organization for Economic Cooperation and Development) countries. Currently, traffic information is provided based on nodes and links using the centerlines of the roads. However, detailed speed information is unavailable. This study presents an optimization method for space to represent a dynamic speed-homogeneous space. Vehicle directions were separated by route using azimuth data based on global navigation satellite system (GNSS) location information, and the time mean speed and space mean speed were used to determine the homogeneous space of vehicle speed through the gradual separation of space. The processing speed of large-capacity data was increased by using Geohash, which applied a quaternary basis segmentation method that split data into two directions of longitude and latitude. The numbers of homogeneous speed spaces along the two directions of the Gyeongbu Expressway were determined to be 127 and 170, respectively, by the 12-step segmentation method. Spaces not included in the range of homogeneous speed spaces amounted to 5.19% and 7.51%, respectively, along the northbound and southbound roadways of the Gyeongbu Expressway. These non-convergence spaces were analyzed by the influence of vehicles entering or exiting slowly from the merging and diverging areas of the freeway junctions and interchanges. In other words, these were analyzed by the difference of speed by lane and not the driving direction.
      Citation: Transportation Research Record
      PubDate: 2022-05-19T09:25:45Z
      DOI: 10.1177/03611981221085536
       
  • Implementation of American Association of State Highway and Transportation
           Officials/American Welding Society D1.5 Phased Array Ultrasonic Weld
           Inspection Programs

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      Authors: Hoda Azari, Russell Kok
      Abstract: Transportation Research Record, Ahead of Print.
      This paper describes highlights of phased array ultrasonic testing (PAUT) nondestructive evaluation (NDE) research activities at the Federal Highway Administration’s (FHWA’s) Advanced Sensing Technology (FAST) NDE Laboratory. The work supports the goal to implement ultrasonic techniques in lieu of radiographic techniques for American Association of State Highway and Transportation Officials (AASHTO)/American Welding Society (AWS) D1.5 Bridge Welding Codeinspection of full penetration bridge fabrication welds. The paper also describes some of the advantages and disadvantages of the process to implement a PAUT inspection program. The results of this study support the goal of broader implementation of ultrasonic testing (UT) with results to date showing a good correlation of the comparative inspection results between PAUT and radiography. There is, however, a need to develop a more comprehensive set of weld flaws to ensure a fully representative flaw set is evaluated. To support that goal, the FAST NDE Laboratory is currently using ultrasonic simulation software to 03611981221090236ement the test plate data with a virtual database of simulated flaws. A successful implementation of PAUT can result in a more efficient inspection process with detailed permanent records and images of the flaw locations mimicking the historic radiograph. As more bridge fabrications incorporate PAUT, there will be a broader PAUT experience base as the AWS committee, teamed with the bridge fabricators, FAST NDE Laboratory, and other contributors continue to work toward replacing all required radiography in AWS D1.5 with an option to use PAUT.
      Citation: Transportation Research Record
      PubDate: 2022-05-18T10:04:43Z
      DOI: 10.1177/03611981221090240
       
  • Real-Time Distributed Cooperative Adaptive Cruise Control Model
           Considering Time Delays and Actuator Lag

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      Authors: Yingtong Tan, Kuilin Zhang
      Abstract: Transportation Research Record, Ahead of Print.
      Real-time control of a fleet of Connected and Automated Vehicles (CAV) for Cooperative Adaptive Cruise Control (CACC) is a challenging problem concerning time delays (from sensing, communication, and computation) and actuator lag. This paper proposes a real-time predictive distributed CACC control framework that addresses time delays and actuator lag issues in the real-time networked control systems. We first formulate a Kalman Filter-based real-time current driving state prediction model to provide more accurate initial conditions for the distributed CACC controller by compensating time delays using sensing data from multi-rate onboard sensors (e.g., Radar, GPS, wheel speed, and accelerometer), and status-sharing and intent-sharing data in BSM via V2V communication. We solve the prediction model using a sequential Kalman Filter update process for multi-rate sensing data to improve computational efficiency. We propose a real-time distributed MPC-based CACC controller with actuator lag and intent-sharing information for each CAV with the delay-compensated predicted current driving states as initial conditions. We implement the real-time predictive distributed CACC control algorithms and conduct numerical analyses to demonstrate the benefits of intent-sharing-based distributed computing, delay compensation, and actuator lag consideration on string stability under various traffic dynamics.
      Citation: Transportation Research Record
      PubDate: 2022-05-18T10:01:02Z
      DOI: 10.1177/03611981221091762
       
  • Classification of Flexible Pavements Based on Texture Data

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      Authors: Christian A. Sabillon, Joaquin Hernandez, Maria Bassil, Jorge Prozzi
      Abstract: Transportation Research Record, Ahead of Print.
      The strong correlations between pavement texture and other surface characteristics—such as friction, drainage, and noise—are widely known. However, those relationships are not straightforward and have a strong dependency on the type and properties of the pavement surface. Incorporating surface information into a prediction model for skid resistance has the potential to drastically increase its predictive power. Nonetheless, in practice, pavement surface information is often unknown at the network level and must be inferred based on local expertise. The objective of this study was to address this issue by developing an objective classification model capable of identifying different asphalt pavement surfaces with a high degree of accuracy using only field texture data. High-resolution texture data were collected on 21 highway sections with varying surface types within 60 mi of the city of Austin, Texas using a prototype developed in house. Sophisticated data-processing algorithms were created to ensure the data used in developing the classification model were of the highest possible quality. Based on the most recent literature on the topic, more than 20 texture summary statistics were assessed during this study to find the best combination to predict surface characteristics of asphalt pavements.The results are robust and indicate that texture summary statistics alone, when used in the right combination, have enough information to develop a pavement surface classification model with a predictive power as high as 89% based on the F1 score.
      Citation: Transportation Research Record
      PubDate: 2022-05-18T09:58:42Z
      DOI: 10.1177/03611981221091560
       
  • Determining Yellow Change and Clearance Intervals for Left-Turning Phases:
           Evaluation of the Current Guidelines with Connected Vehicle Data

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      Authors: Zachary Jerome, Xingmin Wang, Shengyin Shen, Henry X. Liu
      Abstract: Transportation Research Record, Ahead of Print.
      In March 2020, the Institute of Transportation Engineers (ITE) published new guidelines for determining traffic signal change and clearance intervals that included using an extended kinematic equation for left turns. Whereas previous guidelines assumed constant speed for all vehicles approaching an intersection, this new equation accounted for left-turning vehicles needing more yellow time because they decelerate (assuming a maximum safe and comfortable rate) before making turning maneuvers. This paper evaluates these guidelines using real-world vehicle trajectories from the Ann Arbor Connected Vehicle Test Environment (AACVTE). These trajectories confirm that free-flowing left-turning vehicles decelerate, but deceleration usually starts at a moderate rate before reaching the critical distance and continues to the middle of the intersection. Vehicles then accelerate to a departure speed at the clearance point. Since the goal of the yellow change interval is to eliminate the dilemma zone such that a free-flowing vehicle can safely traverse the critical distance, these observations imply that the extended kinematic equation will overestimate the required duration for the following two reasons: (1) the critical distance is shortened by the speed reduction before the braking point; (2) the average traversing speed is higher as vehicles usually decelerate at a moderate rate instead of the maximum rate. The equation will underestimate the clearance interval as the average traversing speed through the intersection is slower than the intersection entry speed. We propose a new left-turn kinematic equation for determining yellow change and clearance intervals, and the results are validated from the observed vehicle trajectories.
      Citation: Transportation Research Record
      PubDate: 2022-05-18T09:53:43Z
      DOI: 10.1177/03611981221091557
       
  • Understanding Crash Risk Using a Multi-Level Random Parameter Binary Logit
           Model: Application to Naturalistic Driving Study Data

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      Authors: Lauren Hoover, Tanmoy Bhowmik, Shamsunnahar Yasmin, Naveen Eluru
      Abstract: Transportation Research Record, Ahead of Print.
      This study presents a framework to employ naturalistic driving study (NDS) data to understand and predict crash risk at a disaggregate trip level accommodating for the influence of trip characteristics (such as trip distance, trip proportion by speed limit, trip proportion on urban/rural facilities) in addition to the traditional crash factors. Recognizing the rarity of crash occurrence in NDS data, the research employs a matched case-control approach for preparing the estimation sample. The study also conducts an extensive comparison of different case-to-control ratios including 1:4, 1:9, 1:14, 1:19, and 1:29. The model parameters estimated with these control ratios are reasonably similar (except for the constant). Employing the 1:9 sample, a multi-level random parameters binary logit model is estimated where multiple forms of unobserved variables are tested including (a) common unobserved effects for each case-control panel, (b) common unobserved factors affecting the error margin in the trip distance variable, and (c) random effects for all independent variables. The estimated model is calibrated by modifying the constant parameter to generate a population conforming crash risk model. The calibrated model is employed to predict crash risk of trips not considered in model estimation. This study is a proof of concept that NDS data can be used to predict trip-level crash risk and can be used by future researchers to develop crash risk models.
      Citation: Transportation Research Record
      PubDate: 2022-05-18T09:51:11Z
      DOI: 10.1177/03611981221090943
       
  • Mechanical Testing Methods for Evaluating Thermoplastic Permanent Pavement
           Markings

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      Authors: Hyungyung Jo, Matthew Giroux, Kendra A. Erk, Chelsea S. Davis
      Abstract: Transportation Research Record, Ahead of Print.
      The durability of permanent pavement markings (PPMs) on roadways is important for drivers’ safety. There are two primary mechanical failure modes: cohesive failure that occurs internally in PPMs through small defects, such as internal pores, and adhesive failure that occurs along the interface between PPMs and road surfaces. Thus, it is critical to characterize the intrinsic mechanical properties of PPMs as well as the adhesion of PPMs on road surfaces to understand their mechanical performance and, ultimately, the durability of PPMs. In this study, the flexural modulus and strength of PPMs were characterized via three-point bend testing, while fracture toughness was determined with single edge notch bend testing. To analyze the adhesive performance of PPMs on asphalt, a shear adhesion testing approach was developed to measure the apparent debonding energy of PPM specimens on asphalt. The shear adhesion test was performed on asphalt road surfaces and cut surfaces to investigate the chemical and mechanical interfacial effects on adhesion. Two commercial thermoplastic PPMs with different mechanical properties were investigated to study how various factors directly affect the adhesion of PPMs on asphalt surfaces. Through mechanical tests, the relationships between the intrinsic materials properties and the mechanical performance of PPMs on asphalt were studied. A PPM material that had lower modulus and higher deformation energy exhibited greater adhesion performance on asphalt, especially when the PPM material was applied at higher asphalt surface temperatures on rough asphalt surfaces.
      Citation: Transportation Research Record
      PubDate: 2022-05-18T09:46:41Z
      DOI: 10.1177/03611981221090236
       
  • Investigating Combined Impact of Adverse Road-Weather Conditions and Heavy
           Vehicles on Saturation Headway

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      Authors: Ryutaro Hirose, Babak Mehran, Agnivesh Pani
      Abstract: Transportation Research Record, Ahead of Print.
      Adverse road-weather (RW) conditions make driving behavior more conservative and the headway during saturated conditions longer, leading to a significant reduction in the capacity of signalized intersections. Past studies indicate that the degree of the influence of adverse RW conditions on intersection performance changes by heavy vehicle (HV) ratio in traffic flow. However, little is known about the combined impacts of adverse RW conditions and HV ratio on saturation headway and how they can be considered in the planning of signalized intersections in areas with long winter. To fill this research gap, in this study the saturation headway data for over 2,000 signal cycles were extracted from video recordings at two signalized intersections in Winnipeg, Canada. The combined impacts of adverse RW conditions and HV ratios are statistically investigated in the paper with due focus given to saturation headway distributions and models. To account for differences in vehicle type, passenger car equivalent and headway distributions are evaluated under different RW conditions. The analysis findings suggest that the saturation headways increased by up to 38.7% as a result of adverse RW conditions. The multiple regression analyses incorporating HV ratios quantify the relationship between saturation headway and various sets of explanatory variables covering adverse RW conditions and roadway geometric factors. The model estimation results reveal that HVs are less sensitive to RW conditions than passenger vehicles. Overall, the study findings will help in designing signalized intersections under adverse RW conditions with various HV ratios.
      Citation: Transportation Research Record
      PubDate: 2022-05-18T09:43:57Z
      DOI: 10.1177/03611981221089303
       
  • Establishment of a Quantitative Time Conversion Relationship Between
           Laboratory Accelerated Weathering Aging and Outdoor Natural Aging of the
           High-Content Polymer Modified Asphalt Applied in Porous Asphalt Pavement:
           From Theory to Experiment

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      Authors: Mingjun Hu, Hangtian Ni, Daquan Sun, Lei Xu
      Abstract: Transportation Research Record, Ahead of Print.
      The purpose of this study was to determine the quantitative time conversion relationship between indoor accelerated weathering aging (AWA) and outdoor natural aging of the high-content polymer modified asphalt (HCPMA) applied in porous asphalt pavement from both theoretical and experimental aspects. Firstly, the calculated aging acceleration rate of the AWA test was determined based on orthogonal analysis and chemical reaction kinetics. The indoor AWA test (0–12 days) and outdoor natural aging (0–12 months) were then performed on HCPMA, and the dynamic shear rheology test and multiple stress creep recovery test were conducted to investigate the rheological properties of HCPMA. Furthermore, the measured aging acceleration rate of the AWA test was determined according to rheological index comparison and then compared with the calculated aging acceleration rate to obtain the ultimate time conversion relationship between indoor and outdoor aging. Results show that it is practical to simulate the natural aging by using the AWA test. HCPMA exhibits similar changes in macroscopic rheological properties in indoor AWA and outdoor natural aging. According to the comparison of rheological indexes, the measured aging acceleration rate of HCPMA under the harshest aging condition is 57.5–120, which is basically consistent with the calculated aging acceleration rate (66) by the chemical reaction kinetics. This further demonstrates the feasibility of this study for determining the indoor-outdoor aging time conversion relationship from theoretical and experimental aspects.
      Citation: Transportation Research Record
      PubDate: 2022-05-18T09:39:47Z
      DOI: 10.1177/03611981221086937
       
  • Material and Structural Characterization of a Wind Turbine Blade for Use
           as a Bridge Girder

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      Authors: Kieran Ruane, Zoe Zhang, Angela Nagle, An Huynh, Ammar Alshannaq, Asha McDonald, Paul Leahy, Marios Soutsos, Jennifer McKinley, Russell Gentry, Lawrence Bank
      Abstract: Transportation Research Record, Ahead of Print.
      Fiber reinforced polymer (FRP) composite materials have been used in a variety of civil and infrastructure applications since the early1980s, including in wind turbine blades. The world is now confronting the problem of how to dispose of decommissioned blades in an environmentally sustainable manner. One proposed solution is to repurpose the blades for use in new structures. One promising repurposing application is in pedestrian and cycle bridges. This paper reports on the characterization of a 13.4-m long FRP wind blade manufactured by LM Windpower (Kolding, Demark) in 1994. Two blades of this type were used as girders for a pedestrian bridge on a greenway (walking and biking trail) in Cork, Ireland. The as-received geometric, material, and structural properties of the 27 year-old blade were obtained for use in the structural design of the bridge. The material tests included physical (volume fraction and laminate architecture) and mechanical (tension and compression) tests at multiple locations. Full-scale flexural testing of a 4-m long section of the blade between 7 and 11 m from the root of the blade was performed to determine the load-deflection behavior, ultimate capacity, strain history, and failure modes when loaded to failure. Key details of the testing and the results are provided. The results of the testing revealed that the FRP material is still in excellent condition and that the blade has the strength and stiffness in flexure to serve as a girder for the bridge constructed.
      Citation: Transportation Research Record
      PubDate: 2022-05-18T01:51:25Z
      DOI: 10.1177/03611981221083619
       
  • Micromobility Trip Origin and Destination Inference Using General
           Bikeshare Feed Specification Data

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      Authors: Yiming Xu, Xiang Yan, Virginia P. Sisiopiku, Louis A. Merlin, Fangzhou Xing, Xilei Zhao
      Abstract: Transportation Research Record, Ahead of Print.
      Emerging micromobility services (e.g., e-scooters) have a great potential to enhance urban mobility but more knowledge on their usage patterns is needed. The General Bikeshare Feed Specification (GBFS) data are a possible source for examining micromobility trip patterns, but efforts are needed to infer trips from the GBFS data. Existing trip inference methods are usually based on the assumption that the vehicle identity (ID) of a micromobility option (e-scooter or e-bike) does not change, and so they cannot deal with data with vehicle IDs that change over time. This paper proposes a comprehensive package of algorithms to infer origin–destination (OD) pairs from GBFS data with static vehicle ID and unlinked trip origins and destinations from GBFS data with resetting and dynamic vehicle ID. The algorithms were implemented in Washington D.C. by analyzing one week (last week of February 2020) of GBFS data published by six vendors, and the inference accuracy of the proposed algorithms are evaluated by R-squared, mean absolute error, and sum absolute error. It is found that the R-squared measure is larger than 0.9 and the MAE measure is less than 2 when the algorithms are evaluated with a 400 m × 400 m grid. The absolute errors are relatively larger in the downtown area, and the inference error is relatively high during early morning and early nighttime. The accuracy of the trip inference algorithms is sufficiently high for most practical applications.
      Citation: Transportation Research Record
      PubDate: 2022-05-14T09:01:57Z
      DOI: 10.1177/03611981221092005
       
  • Investigating the Effects of Pedestrian-to-Vehicle Human–Machine
           Interface Design Using Driving Simulator Experiment

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      Authors: Mohamed Abdel-Aty, Lishengsa Yue, Yina Wu, Ou Zheng
      Abstract: Transportation Research Record, Ahead of Print.
      Pedestrian-to-vehicle (P2V) warning technology is expected to reduce pedestrian crashes and improve roadway safety. Previous studies have demonstrated the effectiveness of P2V; however, compared with a general P2V human–machine interface (HMI) design adopted in these studies, the necessity of applying different HMI designs specific to driving scenarios remains uncertain. To resolve the issue, this study conducted a driving simulator experiment to test the performance of various P2V HMI designs considering scenario heterogeneity. Two aspects of the HMI design, that is, the warning urgency level and warning content, were tested in five pedestrian pre-crash scenarios. The warning urgency level is categorized into two types, a “gradually changed” warning and an “emergency” warning, and the warning content focuses on either providing scenario-based distance information as a supplement or not. Data from 36 participants were collected in the study. The results show that using a “gradually changed” warning design can help a driver make gradual driving adjustments to the upcoming conflict, which improves the driving performance; in addition, providing scenario-based distance information can increase the safety buffer. Additionally, insights about driver features’ effects on P2V HMI design were also proposed. Drivers who had been in a not-at-fault crash before and their experience related to the advanced driver assistance system would interact with the P2V influence. This study’s findings have practical implications for both automobile manufacturers and researchers.
      Citation: Transportation Research Record
      PubDate: 2022-05-14T09:00:48Z
      DOI: 10.1177/03611981221091552
       
  • Vertical Clearance Assessment of Overpassing Structures on Sag Vertical
           Curves

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      Authors: Stergios Mavromatis, Vassilios Matragos, Panagiotis Pasias, Konstantinos Nakas
      Abstract: Transportation Research Record, Ahead of Print.
      The paper investigates areas on sag vertical alignments where overpassing structures impose restrictions on truck drivers’ sight distance. The assessment is performed for the least desired case where the driver’s sightline is equivalent to the defined stopping sight distance (SSD). The overall objective is to define the boundaries where such overpassing structures limit the available sight distances for truck drivers below the required SSD and thus to provide valuable guidance to practitioners. Initially, the authors addressed the SSD calculation on variable grades during the braking process through an earlier approach based on the point mass model and the laws of mechanics. As a second step, truck deceleration rates were determined from the literature. The effect of various design speeds was examined, corresponding to specific ranges of grade values and sag vertical curvature rates. The methodology was based on calculating the difference between the truck driver’s line of sight and the road alignment at fixed locations and associating the defined value with the desired vertical clearance rate (VC). The analysis revealed that critical cases arise for design speed values between 90 km/h and 110 km/h. The examined cases for Vdesign = 100 km/h and Vdesign = 110 km/h revealed more critical concerns since the assessment showed that even a VC value of 4.90 m is not adequate to address SSD provision. Such cases require further attention, especially when the entering downgrade to the sag vertical curve is long and steep.
      Citation: Transportation Research Record
      PubDate: 2022-05-12T06:08:08Z
      DOI: 10.1177/03611981221083618
       
  • Identification of the Main Environmental Impact Categories Over the Life
           Cycle of Hot Mix Asphalt: An Application to Green Public Procurement

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      Authors: David Hernando, Ben Moins, Wim Van den bergh, Amaryllis Audenaert
      Abstract: Transportation Research Record, Ahead of Print.
      Increased environmental awareness has led road agencies to consider the implementation of green public procurement (GPP). Besides sustainability rating systems, environmental indicators can also be implemented in GPP to help road agencies make informed decisions about the environmental impact of the pavement works they procure. A vast literature review revealed that it is still unclear which impact categories are responsible for the majority of the total environmental impact of asphalt mixtures. The objective of this study was to identify the impact categories with the greatest contribution to the total environmental impact of hot mix asphalt so that they can be implemented in the form of environmental indicators in GPP. The scope included conventional and polymer-modified binder and three mix design alternatives: only virgin aggregate, reclaimed asphalt pavement (RAP), and RAP with rejuvenators. The cradle-to-cradle life cycle assessment (LCA) performed showed that global warming (GW), fine particulate matter formation, fossil resource scarcity, and human non-carcinogenic toxicity were responsible for at least 90% of the total impact according to the ReCiPe 2016 hierarchic assessment method. Therefore, a simplified LCA focusing on these four impact categories seems sufficient for the purpose of comparing the environmental performance of alternatives in GPP. It was also found that GW alone accounted for approximately 50% of the total impact, which seems to make GW a good surrogate for the total impact among the asphalt mixtures evaluated. Future work should investigate whether the conclusions from this study still hold up when using secondary materials, lower temperature mixing technologies, or in-situ recycling.
      Citation: Transportation Research Record
      PubDate: 2022-05-12T06:06:39Z
      DOI: 10.1177/03611981221083616
       
  • Impacts of Field and Laboratory Long-Term Aging on Asphalt Binders

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      Authors: Punit Singhvi, Javier J. García Mainieri, Hasan Ozer, Brajendra Kumar Sharma, Imad L. Al-Qadi, Kelly L. Morse
      Abstract: Transportation Research Record, Ahead of Print.
      Asphalt binder aging accelerates cracking of flexible pavement. Quantifying the extent of binder aging allows the formulation and selection of appropriate binders for flexible pavement applications. Asphalt binder aging depends on climatic exposure, asphalt concrete field-surface density, and binder chemistry. The aim of this work was to select a laboratory-aging protocol to represent realistic field aging in Illinois. Binders were extracted from field cores aged from eight to 31 years. Extracted binders were tested for rheology and chemical characteristics. Small- and large-strain rheological parameters were determined. In addition, chemical functional groups and molecular weight distribution of extracted binders were evaluated. Effects of aging across pavement depth were also investigated. Double pressure-aging vessel (PAV) was identified as a suitable laboratory long-term aging protocol to represent eight to 12 years of aging for flexible pavements in Illinois. Thresholds were proposed for selected small- and large-strain rheological parameters representing realistic field aging. These thresholds may be used for binder selection and procurement to ensure the binder’s long-term performance. Furthermore, chemical analysis on extracted binders showed that only specific carbonyl functional groups are affected by field aging.
      Citation: Transportation Research Record
      PubDate: 2022-05-12T06:03:41Z
      DOI: 10.1177/03611981221083614
       
  • Pedestrians and the Built Environment during the COVID-19 Pandemic:
           Changing Relationships by the Pandemic Phases in Salt Lake County, Utah,
           U.S.A.

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      Authors: Keunhyun Park, Patrick A. Singleton, Simon Brewer, Jessica Zuban
      Abstract: Transportation Research Record, Ahead of Print.
      The COVID-19 pandemic has dramatically altered people’s travel behavior, in particular outdoor activities, including walking. Their behavior changes may have prolonged effects after the pandemic, and such changes vary by the context and are related to the characteristics of the built environment. But empirical studies about the relationships between pedestrians and the built environment during the pandemic are lacking. This study explores how COVID-19 and related travel restrictions have affected the relationship between pedestrian traffic volume and the built environment. We estimate daily pedestrian volumes for all signalized intersections in Salt Lake County, Utah, U.S.A., from pedestrian push-button log data between January 2019 and October 2020. Multilevel spatial filtering models show that the COVID-19 pandemic has altered the relationship between pedestrian traffic volume and the built environment. During the pandemic, the higher the number of COVID-19 cases, the less (or more negative) the effects of density, street connectivity, and destination accessibility on pedestrian volume being observed. The exception is access to urban parks, as it became more significant in increasing pedestrian activities during the pandemic. The models also highlight the negative impacts of the pandemic in economically disadvantaged areas. Our findings could help urban and transportation planners find effective interventions to promote active transportation and physical activity amid the global pandemic.
      Citation: Transportation Research Record
      PubDate: 2022-05-12T05:56:21Z
      DOI: 10.1177/03611981221083606
       
  • Evaluation of Different Surface Treatments to Extend Pavement Life

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      Authors: Harikrishnan Nair, Kevin McGhee
      Abstract: Transportation Research Record, Ahead of Print.
      When applied at the right time, pavement preservation treatments can restore a smooth, safe driving surface while delaying the cost for rehabilitation, resulting in reduced life cycle cost. The purpose of this study was to evaluate the performance of three preventive maintenance treatments applied to US 301 in Sussex County, Virginia, to extend pavement life. This paper documents the installation of a Cape seal application of fiber-reinforced chip seal (with microsurfacing on top) over an existing asphalt pavement. A performance comparison was made with more conventional surface treatment options: regular Cape seal (modified single chip seal with microsurfacing), and microsurfacing without a chip seal. Five years after the treatment application, a visual survey complemented by automated distress data from the Virginia Department of Transportation Pavement Management System showed that the section with fiber-reinforced chip seal and microsurfacing performed well with very little reflective cracking. The modified single chip seal with microsurfacing (i.e., regular Cape seal) also performed well, but reflective cracking was higher compared with the fiber-reinforced section. The control section (microsurfacing only) showed extensive cracking after 5 years. This study showed that pavement preservation activities such as the use of fiber-reinforced chip seal with microsurfacing and modified single seal with microsurfacing improved both the pavement condition and the surface characteristics in a very cost-effective manner (based on initial cost). However, long-term performance data are needed to evaluate the benefit/cost of each treatment.
      Citation: Transportation Research Record
      PubDate: 2022-05-12T05:53:01Z
      DOI: 10.1177/03611981221083604
       
  • Exploring Bicyclists’ Visual Attention during Conflicts with Truck
           Traffic

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      Authors: Masoud Ghodrat Abadi, Patrick Maloney, David Hurwitz
      Abstract: Transportation Research Record, Ahead of Print.
      To determine how bicyclists allocate their visual attention, measurable eye-fixations of bicyclists during conflicts with a truck maneuvering at a commercial vehicle loading zone (CVLZ) were studied in a bicycling simulator environment. The potential influence of pavement markings in the conflict area (white lane markings, solid green, and dashed green), truck traffic (parked and exiting), and bicyclists’ gender (female and male) on bicyclists’ visual attention were investigated. Results of a mixed repeated-measures analysis of variance indicated that the type of truck maneuver in the CVLZ had the most significant effect on bicyclists’ visual attention. Dashed green bike lanes were more effective than other design practices to attract bicyclists’ visual attention. It was also found that men fixated more on pavement markings than women regardless of truck maneuver or of pavement marking type.
      Citation: Transportation Research Record
      PubDate: 2022-05-12T05:49:01Z
      DOI: 10.1177/03611981221091709
       
  • Representation of Work-Related Trip Patterns in Household and Commercial
           Travel Surveys

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      Authors: Anna Reiffer, Lukas Barthelmes, Martin Kagerbauer, Peter Vortisch
      Abstract: Transportation Research Record, Ahead of Print.
      This paper considers which work-related trip patterns are included in household travel surveys and which in commercial travel surveys and if there are certain patterns that are distinctly underrepresented in either one. The study is structured as a comparison between data from a household travel survey and data from a commercial travel survey. Both surveys were conducted in Germany and within close temporal proximity. We applied cluster analysis to identify differences in the data and identify work-related travel patterns. The results show that work-related travel patterns are quite complex. Although some patterns are covered in both surveys, mobile workers’ travel patterns in particular are not represented well in the household travel survey. Furthermore, our analysis shows that not all commercial trips are generated by motorized vehicles and a considerable share of work-related trips are undertaken using public transport or active modes of transport that are not covered by the commercial travel survey. The results indicate that researchers and transport planners creating travel demand models need to pay more attention to work-related travel behavior and acknowledge that depending on the area of study, traditional household travel surveys may not provide a complete sample of the population; however, simply adding data on commercial trips from commercial travel demand models to data from household travel surveys does not provide a complete picture of work-related travel either.
      Citation: Transportation Research Record
      PubDate: 2022-05-12T05:45:57Z
      DOI: 10.1177/03611981221091559
       
  • Advisory-Based Time Slot Management System to Mitigate Waiting Time at
           Container Terminal Gates

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      Authors: Ali Nadi, Alex Nugteren, Maaike Snelder, J.W.C. Van Lint, Jafar Rezaei
      Abstract: Transportation Research Record, Ahead of Print.
      This paper introduces an advisory-based time slot management system (TSMS) to control truck arrivals at seaport terminals with the aim to reduce congestion at terminal gates. A modeling framework is proposed, developed, and applied to assess the impact of a truck arrival shift for a case study in the Port of Rotterdam. This system is designed to apply control policies on truck inflow while taking the behavioral aspect of truck operating companies (TOCs) into account. Discrete choice modeling is used to infer the time-of-day preferences of TOCs for container pick-ups from the exchange of information between port and hinterland stakeholders. These preferences are used to shift truck arrivals to the off-peak period which consequently reduces the high waiting time of trucks at terminals gates. To evaluate the effectiveness of the designed TSMS, a simulation platform that resembles terminal operations has been developed using discrete-event simulation. For the allocation of trucks to a certain time of day, a choice-based stochastic assignment heuristic is designed to approximate the optimum configuration of the truck arrival shift policy experiment. The optimum truck arrival shift design shows that significant gain can be obtained even at a low shift rate.
      Citation: Transportation Research Record
      PubDate: 2022-05-12T05:44:01Z
      DOI: 10.1177/03611981221090940
       
  • Evaluation of Geopolymer for Stabilization of Sulfate-Rich Expansive Soils
           for Supporting Pavement Infrastructure

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      Authors: Jungyeon Jang, Nripojyoti Biswas, Anand J. Puppala, Surya Sarat Chandra Congress, Miladin Radovic, Oscar Huang
      Abstract: Transportation Research Record, Ahead of Print.
      Stabilization of sulfate-rich expansive subgrade soils is a persistent cause of concern for transportation infrastructure engineers and practitioners. The application of traditional calcium-based stabilizers is generally not recommended for treating such soils because of the formation of deleterious reaction products such as ettringite. Sulfate-induced heaving causes severe structural damage to pavements and accounts for enormous expenditure from routine maintenance and rehabilitation activities. A research study was undertaken to evaluate the feasibility of using a metakaolin-based geopolymer (GP) for the treatment of sulfate-rich expansive soil. Laboratory studies were conducted on natural soil and artificially sulfate-rich soils, when treated with either lime or GP, to evaluate and compare the improvements in the engineering properties, including unconfined compressive strength, swelling and shrinkage, and resilient moduli characteristics over different curing periods. Microstructural studies, such as field emission scanning electron microscopy and X-ray diffraction, were performed on treated soils to detect the formation of reaction products. The engineering studies indicate that GP treatment enhanced strength and resilient moduli while suppressing ettringite formation and the associated swell–shrink potential of the treated soils. The microstructural studies showed that GP gels contribute to the improvement of these engineering properties through the formation of a uniform geopolymer matrix. In addition, the absence of a calcium source suppressed the formation of ettringite in the GP-treated soils. Overall, the findings indicate that GPs could be used as a potential alternative to existing traditional stabilizers for treating sulfate-rich expansive soils.
      Citation: Transportation Research Record
      PubDate: 2022-05-12T05:38:43Z
      DOI: 10.1177/03611981221086650
       
  • Traffic Micro-Simulation-Based Evaluation of Bus Priority With Queue Jump
           Lane on an Urban Corridor With Heterogeneous Traffic Operations

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      Authors: Tamojit Ghosh, Kinjal Bhattacharyya, Bhargab Maitra
      Abstract: Transportation Research Record, Ahead of Print.
      Queue jump lane (QJL) is a space-optimal facility-based priority measure for faster and smoother movements of buses in urban areas. This study presents an approach to identify the optimal configurations of QJL, bus advance area, and pre-signal for signalized intersections along an urban corridor in India with heterogeneous traffic operations. As this needs to be carried out before field implementation, the traffic impacts of different scenarios were evaluated utilizing a validated VISSIM traffic micro-simulation model. A validated EnViVer emission modeler was used to estimate the vehicular exhaust emissions. The QJL-based priority measures were found to be more effective than a dedicated bus lane along the corridor during the peak hour, which justifies their applicability in cities with restricted road spaces and high traffic demands. To identify the suitable combination of bus priority along the corridor, three additional scenarios were evaluated: bus-optimal, car-optimal, and passenger-optimal. While the passenger-optimal scenario yielded the best impact on travel time performances, the car-optimal scenario was more effective in total emissions performance at the expense of reduced travel time impacts. The conflict between traffic and emissions performances emphasizes the need for investigation of long-term mode and route choice indicators with implementation of bus priority to identify the future mode shares and subsequent impacts. The study was further extended to identify optimal bus stop operations for the baseline and priority scenarios based on multiple combinations of near-side and far-side stops.
      Citation: Transportation Research Record
      PubDate: 2022-05-12T05:35:20Z
      DOI: 10.1177/03611981221090935
       
  • Gauging Public Attitudes and Preferences Toward a Hypothetical Future
           Public Shared Automated Vehicle System: Examining the Roles of Gender,
           Race, Income, and Health

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      Authors: Noah Wexler, Yingling Fan
      Abstract: Transportation Research Record, Ahead of Print.
      We use data from an originally designed survey instrument administered in the Minneapolis–St. Paul metropolitan area to gauge general attitudes and design preferences for a hypothetical shared automated vehicle (SAV) system. Design considerations include seating, payment and booking logistics, security, and extra space and amenities. We pay particular attention to the role of gender, race, health, and income in shaping these attitudes and preferences. Specifically, we use multiple regression models to uncover general willingness-to-use SAV technology, finding that women are overall less comfortable with the technology, Black and Hispanic participants are more willing to pay for SAV technology and generally display lower magnitude preferences for design considerations. Although results are mixed in both sets of analysis for health status, higher income individuals display higher willingness to pay and higher magnitude preferences for design considerations.
      Citation: Transportation Research Record
      PubDate: 2022-05-10T03:56:19Z
      DOI: 10.1177/03611981221090512
       
  • Evaluating the Sensitivity of Intermediate Temperature Performance Tests
           to Multiple Loose Mixture Aging Conditions Using the FHWA Accelerated
           Loading Facility’s RAP/RAS Experiment

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      Authors: David J. Mensching, Michael D. Elwardany, Varun Veginati
      Abstract: Transportation Research Record, Ahead of Print.
      With the advancement of Balanced Mixture Design (BMD), laboratory performance tests for asphalt materials are being assessed for their relation to cracking performance in the field. However, most BMD applications do not account for long-term aging. This gap limits the appropriateness of thresholds and the potential of BMD to improve pavement performance as more amounts of the additives and reclaimed materials available can behave in drastically different fashions between early, intermediate, and late stages of service. In this study, five mixtures with documented field performance from the Federal Highway Administration’s Accelerated Loading Facility were subjected to long-term oven aging (LTOA) protocols. In addition to reheating loose mixtures containing reclaimed asphalt pavement and shingles, the two LTOA methods were 8 h at 135°C and 3 d at 95°C. The objective of this paper is to compare aging approaches, particularly whether equivalence between long-term aged procedures exists, and to highlight the sensitivity (or lack thereof) of common laboratory mixture performance tests. The Indirect Tensile Cracking (IDEAL-CT), Illinois Flexibility Index, Asphalt Mixture Performance Tester cyclic fatigue, and dynamic modulus tests were employed. The results show a collapse in mixture cracking indices when LTOA is incorporated, raising concerns over BMD implementation using criteria established exclusively with short-term oven aging. Use of [math] presented a universal and logic shift in response from the reheated to LTOA state, affirming utility as an aging index. Blending insights can possibly be gleaned from the data, although 95 and 135°C LTOA procedures yield mostly equivalent linear viscoelastic and cracking indices.
      Citation: Transportation Research Record
      PubDate: 2022-05-10T03:51:37Z
      DOI: 10.1177/03611981221090237
       
  • Systemic Opportunities to Improve Older Pedestrian Safety: Merging Crash
           Data Analysis and a Stakeholder Workshop

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      Authors: Jason C. Anderson, Sirisha Kothuri, Christopher Monsere, David Hurwitz
      Abstract: Transportation Research Record, Ahead of Print.
      This paper presents a framework for improving older pedestrian safety in regard to serious (fatal and incapacitating) crashes, using Oregon as a case study. On review of state and federal practices pertaining to older pedestrian safety, 4 years of crash data identified 112 older (≥65 years) pedestrian serious injury crashes. These data were explored for factors that might be addressed systemically using two methods. First, raw frequencies in the crash data were assessed to determine trends and crash-related factors that are overrepresented. Second, a random forest analysis was conducted to determine important variables for predicting older pedestrian serious injury crashes. Using these crash-related factors, a workshop was held with 18 local stakeholders and experts. As part of the workshop, key crash trends, potential causations, and potential countermeasures by priority of implementation were determined based on perspectives from workshop participants. Three key systemic solutions were identified to improve older pedestrian safety, including improving pedestrian visibility and illumination, implementing treatments for left turns, and shortening pedestrian crossing distances across the state. The framework presented in the current study could be adopted by other agencies to systemically address a wide variety of safety concerns.
      Citation: Transportation Research Record
      PubDate: 2022-05-10T03:44:11Z
      DOI: 10.1177/03611981221089312
       
  • Performance of Aging Timber Bridges based on Field Tests and Deterioration
           Models

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      Authors: Ishwarya Srikanth, Madasamy Arockiasamy, Sudhagar Nagarajan
      Abstract: Transportation Research Record, Ahead of Print.
      This study investigated the performance of timber trestle railroad bridges through field tests on aging open- and ballast-deck bridges. It also developed nonparametric deterioration models based on average time in condition rating (ATICR) and Kaplan–Meier (K-M) estimates to assess the performance of timber highway bridge components using National Bridge Inventory data. This study proposes ATICR-based deterioration models for predicting the condition of timber bridge components. Average service life of highway timber multibeam bridge components under routine maintenance without any reconstruction or rehabilitation was found to be 23 years for the decks, 26 years for the superstructures, and 27 years for the substructures. K-M estimate-based reliability models were developed for probabilistic prediction of bridge safety while accounting for partial information from incomplete bridge condition observations. Based on these models, the median survival year—the number of years for which 50% of the bridge population remains in its current condition without deterioration—was obtained as 10 years for the decks, 14 years for the superstructures, and 12 years for the substructures of timber multibeam bridges. The models also suggested there was an 80% chance the timber bridge components would remain in their current condition without deterioration to a lower condition for a minimum of 3 years. The analysis carried out in this study could help improve the management and maintenance of timber bridges that are currently in operation worldwide.
      Citation: Transportation Research Record
      PubDate: 2022-05-10T03:40:03Z
      DOI: 10.1177/03611981221089297
       
  • Analysis of Current E-Scooter Safety Regulation in a Large U.S. City Using
           Epidemiological Components as a Framework

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      Authors: Liliana Salas-Niño
      Abstract: Transportation Research Record, Ahead of Print.
      E-scooters have been promoted as a solution to environmental and last-mile issues. However, physicians have reported an unusual increase in injured e-scooter riders, calling it an “epidemic.” An epidemiological investigation of e-scooter safety carried out in 2018 characterized injuries associated with e-scooter riders in Austin, TX for a period of 87 days. However, the effectiveness of the city’s current regulation on micromobility devices has not been discussed to determine whether it addresses the risk factors identified in this epidemiological investigation. To address this gap, this paper presents an analysis of the legal framework on micromobility devices from the components of the epidemiology triangle (agent, host, and environment) used by traffic authorities in the 1960s to curtail motor vehicle crashes. This analysis revealed that the current micromobility regulation does not offer practical provisions to tackle safety concerns efficiently. Furthermore, based on the number of motor vehicle crashes reported in Austin for 2018, it was found that if e-scooter riders were to travel the same distance in miles as motor vehicle drivers, there would be approximately 3,700,000 injuries compared with 15,133 motor vehicles injuries. Furthermore, this hypothetical figure does not consider the potential underreporting of e-scooter crashes, meaning that the number of injured people per 100,000 mi traveled on e-scooters could be even higher. At least 108 more injured riders were identified than was initially calculated in the 2018 epidemiological investigation. Overall, this study should encourage local authorities around the world to enact appropriate regulations to tackle safety issues surrounding micromobility devices.
      Citation: Transportation Research Record
      PubDate: 2022-05-10T03:34:53Z
      DOI: 10.1177/03611981221088771
       
  • Development, Crash Testing, and Evaluation of Portable Concrete Barriers
           Gap-Spanning Hardware

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      Authors: Riley J. Ruskamp, Mojdeh Asadollahi Pajouh, Robert W. Bielenberg, Scott K. Rosenbaugh, Ronald K. Faller
      Abstract: Transportation Research Record, Ahead of Print.
      Portable concrete barriers (PCBs) are commonly used to protect work-zone personnel and to shield motorists from hazards in construction areas. It is not uncommon to encounter longitudinal gaps within PCB installations resulting from the practice of constructing and connecting the barriers from different ends during setup or contractor operations. Longitudinal gaps can also be created by tensioning issues following an impact event. These gaps can range from 6 in. to a full barrier segment length of 12.5 ft. Longitudinal gaps between adjacent installations of PCB systems pose a serious safety concern for the errant motorist. Therefore, a need existed to develop a treatment capable of shielding the longitudinal gaps that occur between adjacent installations of PCB systems. In this research, design concepts for the gap-spanning hardware were conceived, and two design concepts were selected for further investigation and refinement through LS-DYNA computer simulation. Based on simulation results and input from the Midwest Pooled Fund Program member states, the design concept utilizing nested thrie-beam spanning the gap was chosen for full-scale crash testing under Manual for Assessing Safety Hardware 2016 (MASH 2016). Two tests were conducted to MASH test no. 3-11 to evaluate the length of need of the system, as well as the transition from the gap-spanning hardware to the PCBs. In both tests, the 2270P vehicle was contained and safely redirected. Recommendations are provided for system implementation and future installation with current PCB systems.
      Citation: Transportation Research Record
      PubDate: 2022-05-10T03:31:26Z
      DOI: 10.1177/03611981221088204
       
  • Understanding Factors Associated with Commuter Rail Ridership: A Demand
           Elasticity Study of the GO Transit Rail Network

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      Authors: Aaron Shantz, Jeff Casello, Clarence Woudsma, Erick Guerra
      Abstract: Transportation Research Record, Ahead of Print.
      Planners have theorized that transitioning commuter rail systems to regional rail networks will increase ridership, balance mode share, and reduce automobile use in North American cities. This process is currently underway in Ontario, Canada, as service is being expanded throughout the GO Transit commuter rail network. Calculating elasticities is a common approach used to identify factors that, if adapted, may significantly influence transit demand. However, few studies have focused on identifying demand elasticities specific to the current case of upgrading commuter rail systems in the North American context. The purpose of this study is to fill this gap. Station-level ridership data were compiled for the GO system from January 2016 to December 2019. Smartcard data were used to estimate station catchment areas for which land use, socioeconomic, and demographic datasets were developed. Data about additional factors related to station access, service quantity, fare price, and availability of substitute transport modes were also compiled. Controlling for trip type (e.g., a.m. peak and evening off-peak), demand models were estimated using a random effect panel data estimator. This study finds that service quantity, population density, fuel price, and unemployment rate were significantly associated with commuter rail ridership, regardless of trip type examined. Employment density and seasonal variation were also significant, although different signs were shown between models. The results suggest that plans for this kind of transition should include other considerations in addition to service quantity improvements. Those directed toward the implementation of transit-oriented developments, transport pricing schemes, and competitive fare price strategies are outlined.
      Citation: Transportation Research Record
      PubDate: 2022-05-09T06:09:00Z
      DOI: 10.1177/03611981221082573
       
  • Economic and Environmental Impacts of Platoon Trucks on Pavements

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      Authors: Qingwen Zhou, Imad L. Al-Qadi
      Abstract: Transportation Research Record, Ahead of Print.
      Truck platoons can improve traffic efficiency, safety, and driving comfort, while reducing fuel and driving costs. However, continuous channelized trucks may increase pavement damage, therefore increasing maintenance costs. In this study, an economic and environmental evaluation of the impact on pavement structure of platoon trucks was performed. Four common pavement structures—thick pavement with weak surface layer, thick pavement with strong surface layer, thin pavement with weak surface layer, and thin pavement with strong surface layer—were considered. In addition, four platoon schemes (all channelized platoons, all human-driven trucks, mix of platoon and human-driven trucks, and optimized platoons) were utilized in the study. Compared with human-driven traffic, truck platoons optimized with respect to lane position could reduce pavement damage by 60% for fatigue and 33% for rutting; life-cycle cost, energy consumption, and global warming potential could be reduced by 48%, 31%, and 37%, respectively, for the cases studied. A sensitivity analysis was performed to quantify the impacts of pavement roughness on life-cycle cost analysis and life-cycle assessment. Results showed that a 1 in./mi increment increase in the International Roughness Index per year would increase total energy consumption by 1.2% and total cost by 1.9%. The study recommends that an optimized pavement-lane-position strategy be implemented before permitting general truck platoons.
      Citation: Transportation Research Record
      PubDate: 2022-05-09T05:49:17Z
      DOI: 10.1177/03611981221090242
       
  • Laboratory Evaluation of Warm-Mix Asphalt Open-Graded Friction Courses

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      Authors: Hossam Abohamer, Mostafa A. Elseifi, Corey Mayeux, Samuel B. Cooper, Samuel Cooper
      Abstract: Transportation Research Record, Ahead of Print.
      This study aimed at evaluating the laboratory performance and physical characteristics of warm-mix asphalt (WMA) open-graded friction course (OGFC) mixes prepared with three warm-mix additives (two chemical additives and an organic additive). To achieve this objective, four mixes were prepared including a control mix (CM) prepared with a PG 76-22 binder and two sources of aggregate (i.e., # 78 limestone and # 67 sandstone). Air voids and coefficient of permeability (k) were used to evaluate the functionality of the OGFC mixes. In relation to constructability, the compaction energy index was used to compare the required compaction effort during construction. Furthermore, the Cantabro test, Hamburg wheel-tracking test, Texas overlay test, Modified Lottman, and boil tests were conducted to evaluate durability, permanent deformation, cracking, and moisture-damage resistances of the evaluated mixes. Results indicated that the use of WMA technologies enhanced OGFC durability and performance. Among the evaluated mixes, the organic additive-OGFC met all Louisiana Department of Transportation and Development and NCHRP 01-55 requirements, as it notably enhanced OGFC durability, cracking, and moisture-damage resistance. Furthermore, the use of WMA notably reduced the required compaction effort and mixing temperature needed during production and construction as compared with the CM.
      Citation: Transportation Research Record
      PubDate: 2022-05-09T05:47:17Z
      DOI: 10.1177/03611981221090239
       
  • Influence of Balanced Mix Design Approaches on Pavement Design Making
           Through an Illustrative Example

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      Authors: Rami Chkaiban, Elie Hajj, Adam John Thomas Hand
      Abstract: Transportation Research Record, Ahead of Print.
      Laboratory tests have been developed and used over many years to improve the performance-related predictions of volumetric-based asphalt mix designs. Volumetric property requirements were mainly set for improving field pavement performance. These requirements have been established based on specific material properties. However, with the increased use of innovative and recycled materials, these requirements have shifted from guidelines for achieving a better mix design to guidelines limiting innovation and potential improvements. Therefore, it is time to move toward a balanced mix design (BMD), the ultimate goal of Superpave mix design. According to AASHTO PP 105, four major BMD approaches are available providing different levels of freedom compared with the traditional volumetric-based mix design. In this study, BMD approaches are explored using typical northern Nevada materials. An array of performance tests for rutting and cracking were conducted to evaluate the impact of the test selection on BMD. Moreover, the influence of asphalt mixture components (e.g., binder content, reclaimed asphalt pavement [RAP], recycling agents, gradation) on BMD were investigated. The results show that BMD process conversion is influenced by asphalt mixture properties (e.g., mixtures with similar gradation require different BMD approaches to achieve a well-performing asphalt mixture). Binder content was found to significantly influence BMD performance. In addition, it was concluded that asphalt mixtures with higher RAP content do not necessarily imply worse cracking performance. Furthermore, a poor correlation was observed between asphalt mixture costs and performance, where a mixture with the highest cost did not necessarily yield the best overall performance.
      Citation: Transportation Research Record
      PubDate: 2022-05-09T05:43:37Z
      DOI: 10.1177/03611981221090238
       
  • Development of a Highly Transferable Urban Winter Road Surface
           Classification Model: A Deep Learning Approach

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      Authors: Qian Xie, Tae J. Kwon
      Abstract: Transportation Research Record, Ahead of Print.
      Road surface condition (RSC) is an important performance indicator for winter road maintenance personnel to maintain safe driving conditions. This becomes more apparent in inclement weather events where timely clearing of snow is highly prioritized. Considering the vast road networks that need to be covered, many transportation agencies have been using camera images to view real-time RSC directly; however, monitoring conditions via these cameras is still being done manually, thereby hindering its full utilization for optimizing maintenance services. Many studies have attempted to develop a deep-learning-based approach known as convolution neural network (CNN) to automate the process of RSC image classification. When implemented, RSC can be extracted from road images without human involvement. However, efforts made thus far have been focused on rural highways, with performance in the urban context being the least explored. Furthermore, CNN models developed in previous studies have been trained either from scratch or via transfer learning, but only a few studies have investigated transfer learning using a pre-trained RSC model. To address these gaps, an urban RSC model was developed in this study via transfer learning using a pre-trained RSC CNN model. The image dataset used contains 3914 urban images collected in a residential area south of Edmonton, Alberta. With these images, the pre-trained RSC model was fine-tuned via transfer learning and underwent hyperparameter optimization to boost performance further, yielding a high classification accuracy of 98.21% and an F1-score of 98.4%, which surpassed the accuracy of the model trained from scratch.
      Citation: Transportation Research Record
      PubDate: 2022-05-09T05:39:37Z
      DOI: 10.1177/03611981221090235
       
  • Impact of Road Grade on the Risk Profile of Driver Behavior

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      Authors: Jeanne-Marie Gerber, Johan W. Joubert
      Abstract: Transportation Research Record, Ahead of Print.
      Data generated from telemetry devices, such as acceleration and speed, are used in a variety of industries to determine the risk profile of a driver. This paper considers the addition of road gradient as a contextual variable to a driving behavior model to determine specifically if the risk of a driver is influenced by different road grades. This behavioral risk is demonstrated by comparing the performance of heavy vehicle drivers with and without the addition of road grade as a variable. This is done by using accelerometer data of 48 heavy goods vehicles over an entire month, and appending elevation data from digital elevation model (DEM) data, specifically that of the Shuttle Radar Topography Mission (SRTM), to the vehicles’ GPS traces. The elevation values are used to calculate road grade values which are then categorized in five grade levels. The results show that there is a clear influence of gradient on the behavior of the drivers studied. There is also evidence that steeper sections on a road can cause a change in an individual’s performance when compared with the group.
      Citation: Transportation Research Record
      PubDate: 2022-05-09T05:36:17Z
      DOI: 10.1177/03611981221089939
       
  • Universal Criterion for Interpreting Capacity from Load Tests on Piles

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      Authors: Antonio Kodsy, Magued G. Iskander, Akash Sampurnanand Pandey
      Abstract: Transportation Research Record, Ahead of Print.
      Interpretation of field load tests on piles has many important practical and financial implications in foundation engineering practice. However, identifying the ultimate capacity or resistance on a continuous load settlement curve remains elusive. The geotechnical engineering literature abounds with over 40 criteria to aid in interpreting the ultimate capacity from static load tests on deep foundations. These include settlement, settlement rate, offset, and creep criteria, among others. Since the 1990s criteria proposed by Davisson, AASHTO, and New York City Building Code as well as the 5% and 10% of diameter criteria have evolved to become the most routinely specified for all foundations, without assessing their performance or what they have been intended for. This study provides a side-by-side comparison of the performance of these methods in relation to usability, accuracy, precision, and length and diameter effects. In addition, the performance is also compared with the recently developed NYU criterion where the capacity is taken as the smallest of (i) a settlement corresponding to the elastic compression plus 0.75 in.; (ii) the capacity at plunging or strain-softening; or (iii) settlement corresponding to 5% of the pile diameter, unless the settlement threshold is modified by the structural engineer of record. Assessment is made possible using a database of 350 load tests conducted on square and round concrete piles, open and closed steel pipe piles, as well as H-piles. Comparison suggests that the NYU criterion is the most versatile, precise, and accurate among the examined methods.
      Citation: Transportation Research Record
      PubDate: 2022-05-09T05:33:55Z
      DOI: 10.1177/03611981221084686
       
  • Effects of COVID-19 on Telework and Commuting Behavior: Evidence from
           3 Years of Panel Data

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      Authors: Anna Reiffer, Miriam Magdolen, Lisa Ecke, Peter Vortisch
      Abstract: Transportation Research Record, Ahead of Print.
      The COVID-19 pandemic has forced employers and employees to re-evaluate their attitudes toward telecommuting. This induced a change in the sheer number of people who have started to work from home (WFH). While previous studies highlight differences between telecommuters based on their level of telecommuting experience, these effects have not been studied in detail. This may limit the evaluation of implications for post-pandemic times and the transferability of models and predictions based on data collected during the COVID-19 pandemic. This study expands on previous findings by comparing the characteristics and behavior of those who have started to telecommute during the pandemic and those who had already telecommuted before. Furthermore, this study addresses the uncertainty that exists about whether the findings of studies conducted before the pandemic—for example about sociodemographic characteristics of telecommuters—still hold true, or if the pandemic induced a shift in telecommuters’ profiles. Telecommuters show differences when considering their previous experience in WFH. The results of this study suggest that the transition induced by the pandemic was more drastic for new telecommuters compared with experienced telecommuters. The COVID-19 pandemic had an effect on how household configurations are considered in the choice to WFH. With decreased access to child care resulting from school closings, people with children in the household were more likely to choose to telecommute during the pandemic. Also, while people living alone are generally less likely to choose to WFH, this effect was reduced as a result of the pandemic.
      Citation: Transportation Research Record
      PubDate: 2022-05-07T11:03:37Z
      DOI: 10.1177/03611981221089938
       
  • Impacts of the COVID-19 Pandemic on Pedestrian Push-Button Utilization and
           Pedestrian Volume Model Accuracy in Utah

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      Authors: Ferdousy Runa, Patrick A. Singleton
      Abstract: Transportation Research Record, Ahead of Print.
      This work investigated the impacts of COVID-19 on pedestrian behavior, answering two research questions using pedestrian push-button data from Utah traffic signals: How did push-button utilization change during the early pandemic, owing to concerns over disease spread through high-touch surfaces' How did the accuracy of pedestrian volume estimation models (developed pre-COVID based on push-button traffic signal data) change during the early pandemic' To answer these questions, we first recorded videos, counted pedestrians, and collected push-button data from traffic signal controllers at 11 intersections in Utah in 2019 and 2020. We then compared changes in push-button presses per pedestrian (to measure utilization), as well as model prediction errors (to measure accuracy), between the two years. Our first hypothesis of decreased push-button utilization was partially supported. The changes in utilization at most (seven) signals were not statistically significant; yet, the aggregate results (using 10 of 11 signals) saw a decrease from 2.1 to 1.5 presses per person. Our second hypothesis of no degradation of model accuracy was supported. There was no statistically significant change in accuracy when aggregating across nine signals, and the models were actually more accurate in 2020 for the other two signals. Overall, we concluded that COVID-19 did not significantly deter people from using push-buttons at most signals in Utah, and that the pedestrian volume estimation methods developed in 2019 probably do not need to be recalibrated to work for COVID conditions. This information may be useful for public health actions, signal operations, and pedestrian planning.
      Citation: Transportation Research Record
      PubDate: 2022-05-07T11:01:37Z
      DOI: 10.1177/03611981221089935
       
  • Development of a Model to Estimate Percentage of Reclaimed Asphalt
           Pavement (RAP) Binder Contribution Based on Design and Performance of
           Super High RAP Mixes

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      Authors: Logan Cantrell, Haifang Wen, Lin Wang
      Abstract: Transportation Research Record, Ahead of Print.
      Reclaimed asphalt pavement (RAP) is one of the most recycled materials. The allowed RAP percentage in asphalt mixes is typically limited because of concerns over variability, binder stiffness, cracking performance, and generally the unknown associated with RAP. With abundant RAP stockpiles, the use of higher percentage RAP in asphalt mix may be warranted if performance can meet or exceed low RAP (LR) mixes (20% RAP or lower). In this study, high RAP (HR) mixes (40% RAP) and super high RAP (SHR) mixes (greater than 40% RAP) were designed, and their performance was compared with LR mixes. Mixes that cover two climates, Eastern and Western Washington, were included in this study. A lower performance grade (PG) virgin binder and a bio-based rejuvenator were used in HR and SHR mixes to allow the blended binder to meet the target PG required by the Washington Department of Transportation (WSDOT). Mix volumetrics and binder PGs of these mixes were designed close to each other, indicating the feasibility to produce RAP mixes up to 100% RAP. Overall, the addition of RAP improves the rutting performance but reduces the cracking performance of SHR mixes. Two measures were evaluated to mitigate SHR mixes’ cracking potential, including adding extra 0.5% virgin binder or 50% rejuvenator above the original dose, which improved the cracking performance of SHR mixes but reduced the rutting resistance. Based on these results, a recycled binder contribution model was developed to estimate the percentage of RAP binder contribution based on rutting and cracking performance testing.
      Citation: Transportation Research Record
      PubDate: 2022-05-07T10:59:57Z
      DOI: 10.1177/03611981221089574
       
  • Resilient Characteristics of Polymer Emulsion-Treated Sandy Soil

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      Authors: Prince Kumar, Anand J. Puppala, Jeb S. Tingle, Sayantan Chakraborty, Surya Sarat Chandra Congress
      Abstract: Transportation Research Record, Ahead of Print.
      The current pavement design guidelines, for example, Mechanistic-Empirical Pavement Design Guide (MEPDG), heavily rely on the resilient moduli of pavement materials. Some locally available pavement materials may not meet the design requirements and often require the application of efficient stabilizers. Therefore, the characterization of natural and treated subgrade soils using resilient modulus is important for the design of durable flexible pavements. A research study was designed and conducted to investigate the effect of polymer emulsion treatment on the resilient characteristics of sandy soil, which is used in constructing highways and airport surfaces. A commercially available polymer emulsion was used to stabilize cohesionless soil, and an attempt was made to understand the influence of polymer emulsion dosage and curing time on the strength and resilient characteristics of treated soil mixtures. Several laboratory tests were conducted on mixtures prepared with different dosages and curing times to evaluate the improvement in unconfined compressive strength and resilient moduli properties of treated sandy soil. Multiple regression analyses were conducted on resilient moduli test results using two- and three-parameter models and identified the best model exhibiting a good fit with the experimental data. A case study was demonstrated using the resilient moduli of untreated and polymer emulsion-treated soil to determine the thickness of airfield pavement. Overall, the outcome of the study is expected to assist the state and federal agencies in stabilizing and using problematic sandy soils for constructing various pavement structures.
      Citation: Transportation Research Record
      PubDate: 2022-05-07T10:56:11Z
      DOI: 10.1177/03611981221087238
       
  • Getting There: The Effect of First and Last Mile Infrastructure and
           Services on Rail Ridership

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      Authors: Benjamin Salter, Serena Alexander
      Abstract: Transportation Research Record, Ahead of Print.
      Using linear regression models, this paper analyzes the connection between first and last mile infrastructure and services and ridership at rail stations in two San Francisco Bay Area rail systems: Bay Area Rapid Transit and Caltrain. The findings indicated that bus and shuttle services had a large impact on ridership at stations when demographic data about station-area populations and service data such as the number of trains that serve a station at peak hour were controlled for. Additionally, station area jobs and housing were found to be extremely effective predictors of rail ridership. Each additional resident or job in a station area increased daily ridership by a small but significant amount, suggesting that ridership is ultimately heavily driven by station-area land use. Nevertheless, existing first and last mile plans primarily focus on active transportation modes; these plans neither consider land use nor emphasize the importance of bus and shuttle services as key parts of first and last mile planning. The findings showed a much less conclusive relationship between active transportation improvements, typically the focus of first and last mile plans, and ridership. This finding revealed an opportunity for improving ridership and providing equitable access to transportation and jobs by better linking land use and first and last mile planning efforts and by investing in bus and shuttle services at stations.
      Citation: Transportation Research Record
      PubDate: 2022-05-07T10:52:11Z
      DOI: 10.1177/03611981221089543
       
  • Construction of a Composite Pavement (Asphalt over Concrete) in Virginia

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      Authors: M. Shabbir Hossain, Harikrishnan Nair, H. Celik Ozyildirim
      Abstract: Transportation Research Record, Ahead of Print.
      The U.S. Strategic Highway Research Program 2 (SHRP2) identified composite pavement as a “renewal solution” and the Virginia Department of Transportation (VDOT) received implementation funding to demonstrate its feasibility. In 2017, this funding was applied to support major rehabilitation of two westbound lanes of US 60 in Henrico County, Virginia, a project that essentially replaced 1.1 mi of deteriorated concrete pavement with a new composite system consisting of continuously reinforced concrete pavement (CRCP) overlaid with stone matrix asphalt (SMA). This paper documents the design and construction of this new composite pavement. It also includes results from through-the-thickness temperature monitoring and a summary of performance for the first 4 years after opening to traffic.Close oversight by researchers provided a review of challenges and associated lessons learned from the design and construction process. Current VDOT specifications and standards were sufficient for successful construction. The asphalt overlay appeared to reduce the temperature gradient within the CRCP and to moderate daily temperature swings. This insulating effect of asphalt is expected to lower curling and associated stresses in the concrete pavement, which may permit reduced concrete thickness requirements in designs and also enable longer service life. The cracks in CRCP were tight and were not expected to reflect through the SMA. Moreover, the SMA mixture was tested to be crack and rut resistant. Therefore, a crack- and rut-free long service life for this composite pavement is expected. A recent visual survey by researchers found no observable distresses after 4 years under traffic.
      Citation: Transportation Research Record
      PubDate: 2022-05-07T10:45:55Z
      DOI: 10.1177/03611981221089300
       
  • Development and Evaluation of Top-Mounted Sockets for Weak-Post, Midwest
           Guardrail System on Culverts

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      Authors: Mojdeh Asadollahi Pajouh, Scott Rosenbaugh, Ronald Faller
      Abstract: Transportation Research Record, Ahead of Print.
      New top-mounted sockets for use with the weak-post, Midwest Guardrail System (MGS) on low-fill culverts were developed and evaluated. The system was adapted from the MGS bridge railing for attachment to the top slab of a concrete box culvert. Three design concepts were developed and evaluated through dynamic component testing. Both lateral and longitudinal impact tests were conducted on the design concepts while mounted to simulated concrete culverts. Two concepts, a cylindrical concrete foundation and a steel tube socket assembly, proved strong enough to withstand the impact loads transferred from the posts without sustaining significant damage or displacements. However, the third concept, a concrete slab, fractured and allowed the sockets to rotate back without developing the post bending strength. Thus, only the cylindrical concrete foundation and the steel tube socket assembly in combination with the weak-post, MGS were determined to be crashworthy according to the Manual for Assessing Safety Hardware (MASH) Test Level 3 safety criteria. The new top-mounted, socketed, weak-post, W-beam MGS for low-fill culverts has multiple advantages over other guardrail treatments for culverts. The guardrail system has an unrestricted system length and does not require a transition when attached to the MGS. The top-mounted system can be placed parallel to the roadway with a constant lateral offset regardless of the position and orientation of the culvert headwall. Additionally, the attachment configurations were designed utilizing epoxy anchors, enabling the system to be installed on new or existing culverts. Finally, the sockets remain undamaged during impact events, allowing for quick repairs.
      Citation: Transportation Research Record
      PubDate: 2022-05-07T10:42:56Z
      DOI: 10.1177/03611981221089296
       
  • Performance of Asphalt Mixes Containing Postconsumer Recycled Plastic
           using Balanced Mix Design Approach and Dry Process

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      Authors: Sagar Ghos, Christopher R. Sumter, Paul Cancino Arevalo, Syed Ashik Ali, Musharraf Zaman, Kenneth R. Hobson, Greg Kalicki, Darin Metzer
      Abstract: Transportation Research Record, Ahead of Print.
      In recent years, use of postconsumer recycled (PCR) plastics in asphalt mixes has been gaining popularity owing to increased environmental awareness, and the need to promote sustainability and conserve natural resources. When using the dry process, incorporation of PCR plastic in asphalt mixes poses several challenges, including mixing, sample preparation, and testing. Use of balanced mix design (BMD) for asphalt mixes containing PCR plastic poses additional challenges that have not been adequately covered in previous studies. To this end, changes in the volumetric properties and performance of PCR plastic-modified asphalt mixes were investigated in this study. For this purpose, an asphalt mix having a nominal maximum aggregate size (NMAS) of 9.5 mm and PG 64-22 binder was designed using the BMD approach. Three different percentages (0.25%, 0.5%, and 1% by weight of aggregate) and two different PCR plastics, namely low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE) were incorporated in the mix using the dry process. Volumetric properties, namely maximum theoretical specific gravity, bulk specific gravity, voids in mineral aggregate, voids filled with asphalt, air void contents, and densities were determined for both control- (0% plastic) and modified mixes. Also, indirect tensile strength, indirect tensile asphalt cracking test, and Hamburg Wheel Tracking tests were performed to assess the performance of these mixes. A comparison of performance for both plastic type and amount and issues related to the incorporation of PCR plastic using the dry process are discussed in this paper.
      Citation: Transportation Research Record
      PubDate: 2022-05-07T10:38:41Z
      DOI: 10.1177/03611981221088200
       
  • Development of a Fatigue Damage Model for Roller Compacted Concrete
           Pavement Based on In Situ Saw-Cut Beams and Accelerated Pavement
           Performance

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