Subjects -> TRANSPORTATION (Total: 216 journals)
    - AIR TRANSPORT (9 journals)
    - AUTOMOBILES (26 journals)
    - RAILROADS (10 journals)
    - ROADS AND TRAFFIC (9 journals)
    - SHIPS AND SHIPPING (39 journals)
    - TRANSPORTATION (123 journals)

TRANSPORTATION (123 journals)                     

Showing 1 - 53 of 53 Journals sorted alphabetically
Accident Analysis & Prevention     Hybrid Journal   (Followers: 123)
Analytic Methods in Accident Research     Hybrid Journal   (Followers: 9)
Applied Mobilities     Hybrid Journal   (Followers: 3)
Archives of Transport     Open Access   (Followers: 18)
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: 16)
Cities in the 21st Century     Open Access   (Followers: 17)
Danish Journal of Transportation Research / Dansk Tidsskrift for Transportforskning     Open Access   (Followers: 3)
Decision Making : Applications in Management and Engineering     Open Access   (Followers: 2)
Economics of Transportation     Partially Free   (Followers: 14)
Emission Control Science and Technology     Hybrid Journal   (Followers: 2)
eTransportation     Open Access   (Followers: 2)
EURO Journal of Transportation and Logistics     Hybrid Journal   (Followers: 15)
European Transport Research Review     Open Access   (Followers: 24)
Geosystem Engineering     Hybrid Journal   (Followers: 2)
IATSS Research     Open Access  
IEEE Open Journal of Intelligent Transportation Systems     Open Access   (Followers: 7)
IEEE Vehicular Technology Magazine     Full-text available via subscription   (Followers: 7)
IET Electrical Systems in Transportation     Open Access   (Followers: 11)
IET Intelligent Transport Systems     Open Access   (Followers: 12)
IET Smart Cities     Open Access  
IFAC-PapersOnLine     Open Access   (Followers: 1)
International Journal of Applied Logistics     Full-text available via subscription   (Followers: 11)
International Journal of Crashworthiness     Hybrid Journal   (Followers: 12)
International Journal of e-Navigation and Maritime Economy     Open Access   (Followers: 6)
International Journal of Electric and Hybrid Vehicles     Hybrid Journal   (Followers: 11)
International Journal of Electronic Transport     Hybrid Journal   (Followers: 9)
International Journal of Heavy Vehicle Systems     Hybrid Journal   (Followers: 7)
International Journal of Intelligent Transportation Systems Research     Hybrid Journal   (Followers: 16)
International Journal of Mobile Communications     Hybrid Journal   (Followers: 9)
International Journal of Ocean Systems Management     Hybrid Journal   (Followers: 3)
International Journal of Physical Distribution & Logistics Management     Hybrid Journal   (Followers: 14)
International Journal of Services Technology and Management     Hybrid Journal   (Followers: 1)
International Journal of Sustainable Transportation     Hybrid Journal   (Followers: 19)
International Journal of Traffic and Transportation Engineering     Open Access   (Followers: 19)
International Journal of Transportation Engineering     Open Access   (Followers: 2)
International Journal of Transportation Science and Technology     Open Access   (Followers: 12)
International Journal of Vehicle Systems Modelling and Testing     Hybrid Journal   (Followers: 3)
Journal of Advanced Transportation     Hybrid Journal   (Followers: 16)
Journal of Big Data Analytics in Transportation     Hybrid Journal   (Followers: 2)
Journal of Intelligent and Connected Vehicles     Open Access   (Followers: 2)
Journal of KONES     Open Access  
Journal of Mechatronics, Electrical Power, and Vehicular Technology     Open Access   (Followers: 6)
Journal of Modern Transportation     Full-text available via subscription   (Followers: 9)
Journal of Navigation     Hybrid Journal   (Followers: 286)
Journal of Sport & Social Issues     Hybrid Journal   (Followers: 12)
Journal of Sustainable Mobility     Full-text available via subscription   (Followers: 3)
Journal of Traffic and Transportation Engineering (English Edition)     Open Access   (Followers: 5)
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: 16)
Journal of Transport Geography     Hybrid Journal   (Followers: 28)
Journal of Transport History     Hybrid Journal   (Followers: 13)
Journal of Transportation Safety & Security     Hybrid Journal   (Followers: 10)
Journal of Transportation Security     Hybrid Journal   (Followers: 2)
Journal of Transportation Systems Engineering and Information Technology     Full-text available via subscription   (Followers: 12)
Journal of Transportation Technologies     Open Access   (Followers: 15)
Journal of Waterway Port Coastal and Ocean Engineering     Full-text available via subscription   (Followers: 8)
Journal on Vehicle Routing Algorithms     Hybrid Journal  
Les Dossiers du Grihl     Open Access   (Followers: 1)
LOGI ? Scientific Journal on Transport and Logistics     Open Access   (Followers: 1)
Logistics     Open Access   (Followers: 3)
Logistics & Sustainable Transport     Open Access   (Followers: 6)
Logistique & Management     Hybrid Journal  
Mobility in History     Full-text available via subscription   (Followers: 5)
Modern Transportation     Open Access   (Followers: 12)
Nonlinear Dynamics     Hybrid Journal   (Followers: 20)
Open Journal of Safety Science and Technology     Open Access   (Followers: 18)
Open Transportation Journal     Open Access   (Followers: 1)
Packaging, Transport, Storage & Security of Radioactive Material     Hybrid Journal   (Followers: 4)
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: 15)
Promet : Traffic &Transportation     Open Access  
Public Transport     Hybrid Journal   (Followers: 21)
Recherche Transports Sécurité     Hybrid Journal   (Followers: 1)
Research in Transportation Business and Management     Partially Free   (Followers: 8)
Revista Transporte y Territorio     Open Access   (Followers: 1)
Revue Marocaine de Management, Logistique et Transport     Open Access  
Romanian Journal of Transport Infrastructure     Open Access   (Followers: 1)
SourceOCDE Transports     Full-text available via subscription   (Followers: 2)
Sport, Education and Society     Hybrid Journal   (Followers: 13)
Sport, Ethics and Philosophy     Hybrid Journal   (Followers: 3)
Streetnotes     Open Access   (Followers: 1)
Synthesis Lectures on Mobile and Pervasive Computing     Full-text available via subscription   (Followers: 1)
Tire Science and Technology     Full-text available via subscription   (Followers: 3)
Transactions on Transport Sciences     Open Access   (Followers: 7)
Transport     Open Access   (Followers: 17)
Transport and Telecommunication     Open Access   (Followers: 5)
Transport in Porous Media     Hybrid Journal   (Followers: 2)
Transport Problems     Open Access   (Followers: 5)
Transport Reviews: A Transnational Transdisciplinary Journal     Hybrid Journal   (Followers: 10)
Transport technic and technology     Open Access   (Followers: 1)
Transportation     Hybrid Journal   (Followers: 35)
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: 17)
Transportation Letters : The International Journal of Transportation Research     Hybrid Journal   (Followers: 6)
Transportation Research Interdisciplinary Perspectives     Open Access   (Followers: 3)
Transportation Research Part A: Policy and Practice     Hybrid Journal   (Followers: 41)
Transportation Research Part B: Methodological     Hybrid Journal   (Followers: 39)
Transportation Research Part C: Emerging Technologies     Hybrid Journal   (Followers: 31)
Transportation Research Procedia     Open Access   (Followers: 7)
Transportation Research Record : Journal of the Transportation Research Board     Full-text available via subscription   (Followers: 36)
Transportation Safety and Environment     Open Access   (Followers: 2)
Transportation Science     Full-text available via subscription   (Followers: 26)
Transportation Systems and Technology     Open Access  
TRANSPORTES     Open Access   (Followers: 6)
Transportmetrica A : Transport Science     Hybrid Journal   (Followers: 9)
Transportmetrica B : Transport Dynamics     Hybrid Journal   (Followers: 1)
Transportrecht     Hybrid Journal   (Followers: 1)
Travel Behaviour and Society     Full-text available via subscription   (Followers: 12)
Travel Medicine and Infectious Disease     Hybrid Journal   (Followers: 4)
Urban Development Issues     Open Access   (Followers: 3)
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: 1)
World Review of Intermodal Transportation Research     Hybrid Journal   (Followers: 6)
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: 36  
 
  Full-text available via subscription Subscription journal
ISSN (Print) 0361-1981 - ISSN (Online) 2169-4052
Published by TRB Homepage  [1 journal]
  • 2020 Reviewer Thank You

    • Free pre-print version: Loading...

      Pages: 1 - 41
      Abstract: Transportation Research Record, Volume 2675, Issue 4, Page 1-41, April 2021.

      Citation: Transportation Research Record
      PubDate: 2021-05-26T07:36:38Z
      DOI: 10.1177/03611981211010109
      Issue No: Vol. 2675, No. 4 (2021)
       
  • Crowd-Sensing Road Surface Quality Using Connected Vehicle Data

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      Authors: Jinzhu Chen, Donald K Grimm, Fan Bai, John Grace, Sangeeta Relan, William Vavrik
      Abstract: Transportation Research Record, Ahead of Print.
      This work presents an approach for collecting road surface data using connected vehicles. Road surface readings from multiple production vehicles were collected and aggregated to estimate road roughness measured by the International Roughness Index (IRI). The analysis compared multiple instances of connected vehicle data with high speed pavement profile vehicle (Class 1 profiler) data. A separate analysis compared multiple instances of connected vehicle data to an advanced walking profiler. Results demonstrate the feasibility of harvesting road surface data from the existing connected vehicles to support continuous road surface monitoring applications. Benefits include more timely acquisition of pavement data, broader coverage of the road network, and potential for aiding existing survey fleet in targeting early signs of pavement degradation. Collected roughness measurements were found to be closely aligned with reference devices that were employed as part of this study. A regional experiment in the Detroit Metropolitan area that covered 64 mi of roadways found that the connected vehicle data was highly correlated with Class 1 profiler data where 83% of traveled miles had a 0.8 or higher correlation. Moreover, 85% of the measurements had small absolute errors less than 50 in./mi and half of the measurements had absolute errors less than 20 in./mi. A test track experiment at Virginia Tech Transportation Institute Smart Road facility compared the connected vehicle data to the advanced walking profiler and showed that the correlations for repeatability and reproducibility are 0.90 and 0.91, respectively, which are very close to the standard requirement for certified profilers.
      Citation: Transportation Research Record
      PubDate: 2021-07-20T06:58:31Z
      DOI: 10.1177/03611981211019735
       
  • Public Transport Fleet Replacement Optimization Using Multi-Type
           Battery-Powered Electric Buses

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      Authors: Chunyan Tang, Xiaoyu Li, Avishai (Avi) Ceder, Xiaokun Wang
      Abstract: Transportation Research Record, Ahead of Print.
      To achieve a green and sustainable public transit system, most transit agencies plan to completely replace current diesel and hybrid buses with battery-powered electric buses (EBs) in the decades ahead. Based on performances of EBs in practical operations, this study develops a transit fleet replacement model using multi-type EBs to determine an optimal fleet replacement plan in a cost-effective manner, considering associated diesel–electric replacement rates and in-vehicle crowd costs for passengers. Multi-type EBs include small EBs with fast charging technique, and large EBs with fast and slow charging techniques. The proposed model is applied to a real-life case study of the transit system in Qingdao, China. The results obtained indicate that large EBs with a high price tag are preferentially purchased in the first few years of the analysis period, whereas small EBs with a low price tag are favored in the latter years. The use of multi-type EBs results in a significant saving of the total cost, compared with the use of single-type EBs. Interestingly, with the increase of passenger demand, a large EB with a fast charging method presents more benefits than others. In contrast, a small EB has more advantages in a transit system with low demand.
      Citation: Transportation Research Record
      PubDate: 2021-07-20T06:43:50Z
      DOI: 10.1177/03611981211027157
       
  • Pavement Fatigue Damage Simulations Using Second-Generation
           Mechanistic-Empirical Approaches

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      Authors: Noe Hernandez-Fernandez, John T. Harvey, Benjamin Shane Underwood, Alexandra Ossa-Lopez
      Abstract: Transportation Research Record, Ahead of Print.
      This article aims to demonstrate the advanced features of two second-generation mechanistic-empirical (ME) pavement analysis engines by focusing on their ability to conduct fatigue performance analysis. First, a comprehensive review is presented of both mechanistic and empirical damage models, underlining the additional features of CalME and FlexPAVE™ over AASHTOWare Pavement ME Design. Then, the capabilities of these methodologies are demonstrated by simulating the fatigue damage performance of an example study section. For these simulations the mechanical properties of four asphalt concrete mixtures, assembled in the laboratory with similar mix design attributes but diverse fatigue characteristics, were utilized. The empirical transfer functions were initially calibrated against field cracking for the unmodified mixture cracking predictions. After that, fatigue damage simulations for the other three mixtures were performed. The results showed a similar ranking in fatigue cracking performance for both software simulations. Polymer-modified mixtures exhibited higher fatigue cracking resistance, whereas the unmodified mixture showed the worst cracking resistance. However, significant differences in cracking initiation and progression rates were observed for all mixture simulations before and after calibration. This discrepancy was related to the different approaches to considering traffic loads in each software system, single axle in FlexPAVE™ and axle spectrum in CalME. Finally, current, and future enhancements for both analysis engines are briefly discussed.
      Citation: Transportation Research Record
      PubDate: 2021-07-20T06:42:08Z
      DOI: 10.1177/03611981211027152
       
  • Safety Impacts of Transit Signal Priority Using a Full Bayesian Approach

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      Authors: MD Sultan Ali, Angela E. Kitali, John H. Kodi, Priyanka Alluri, Thobias Sando
      Abstract: Transportation Research Record, Ahead of Print.
      Transit signal priority (TSP) is a strategy that prioritizes the movement of transit vehicles through a signalized intersection to provide better transit travel time reliability and minimize transit delay. Although TSP is primarily intended to improve the operational performance of transit vehicles, it may also have substantial safety benefits. This study explored the potential safety benefits of the TSP strategy deployed at various locations in Florida. An observational before–after full Bayes (FB) approach with a comparison group was adopted to estimate the crash modification factors (CMFs) for total crashes, rear-end crashes, sideswipe crashes, and angle crashes. The analysis was based on 12 corridors equipped with the TSP system and their corresponding 29 comparison corridors without the TSP system. The deployment of TSP was found to reduce total crashes by 7.2% (CMF = 0.928), rear-end crashes by 5.2% (CMF = 0.948), and angle crashes by 21.9% (CMF = 0.781), and these results are statistically significant at a 95% Bayesian credible interval (BCI) except for the rear-end crashes. On the other hand, sideswipe crashes increased by 6% (CMF = 1.060) although the increase was not significant at a 95% BCI. Overall, the results indicated that TSP improves safety. The findings of this study may present key considerations for transportation agencies and practitioners when planning future TSP deployments.
      Citation: Transportation Research Record
      PubDate: 2021-07-20T06:40:48Z
      DOI: 10.1177/03611981211025285
       
  • Estimating Safety Impacts of Adaptive Signal Control Technology Using a
           Full Bayesian Approach

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      Authors: John H. Kodi, Angela E. Kitali, MD Sultan Ali, Priyanka Alluri, Thobias Sando
      Abstract: Transportation Research Record, Ahead of Print.
      Adaptive signal control technology (ASCT) is a traffic management strategy that optimizes signal timing based on real-time traffic demand. Although the primary intent of ASCT is to improve the operational performance of signalized intersections, the technology may also have substantial safety benefits. This study explored the potential safety benefits of the ASCT strategy deployed at signalized intersections in Florida, U.S. An observational before-after full Bayes (FB) approach with a comparison group was adopted to develop crash modification factors (CMFs) for total crashes, rear-end crashes, and specific crash severity levels (fatal plus injury [FI], and property damage only [PDO] crashes). The analysis was based on 20 intersections equipped with ASCT and their corresponding 40 comparison intersections without ASCT. The ASCT deployment was found to significantly reduce total crashes by 7.8% (CMF = 0.922), rear-end crashes by 8.7% (CMF = 0.913), and PDO crashes by 8.1% (CMF = 0.919). The 8.6% reduction in FI crashes (CMF = 0.914) was not significant at a 90% Bayesian credible interval. These findings provide researchers and practitioners with an effective means to quantify the safety benefits of the ASCT strategy and conduct economic appraisals of ASCT deployments.
      Citation: Transportation Research Record
      PubDate: 2021-07-20T06:35:48Z
      DOI: 10.1177/03611981211025281
       
  • Method for Estimating Speed of the Out-of-Control Tractor-Semitrailer on
           Downhill Grades

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      Authors: Menghua Yan, Jinliang Xu, Shuo Han, Yaping Dong, Leyu Wei
      Abstract: Transportation Research Record, Ahead of Print.
      Speed estimation for the out-of-control truck on a downhill grade is essential for passive safety features like truck escape ramps to promote traffic safety. This paper presents a method for estimating the speed of out-of-control trucks based on Newton’s Laws of Motion. First of all, we analyze gravity effort, aerodynamics, and rolling resistance through a free body diagram of an out-of-control truck on a downhill grade. Further, we select the speed as the dependent variable, with the following road and vehicle characteristics as independent variables: road surface type, grade, grade length, truck size, truck weight, and tire type. Finally, we estimate the speed and acceleration according to Newton’s Laws of Motion. The results show that the factors that significantly affect the out-of-control truck’s speed include tire type, road surface coefficient, grade, and grade length. TruckMaker simulation results demonstrate that the model is valid at a 99% confidence level.
      Citation: Transportation Research Record
      PubDate: 2021-07-20T06:34:29Z
      DOI: 10.1177/03611981211024230
       
  • New Mechanistic Procedure to Predict the Critical Cracking Temperature of
           Asphalt Concrete from Bending Beam Rheometer and Indirect Tension Test
           Data

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      Authors: Md Amanul Hasan, Rafiqul A. Tarefder
      Abstract: Transportation Research Record, Ahead of Print.
      This study presents a new mechanistic procedure for determining the critical cracking temperature of asphalt concrete (AC) using data from bending beam rheometer (BBR) test of asphalt binder and indirect tension (IDT) test of AC. This new procedure uses BBR creep data to generate the mixture relaxation modulus mastercurve by utilizing the Hirsch model, time-temperature superposition principle, and Prony series-based interconversion method. The Hirsch model parameters are calibrated by comparing creep data from BBR and IDT creep tests performed at the same temperature. Boltzmann hereditary integral and second-order heat equation are then used to calculate thermal stress from the developed relaxation modulus mastercurve. IDT strength data is transferred from test strain rate to thermal strain rate using the viscoelastic continuum damage model. Since a strain gauge is not attached for traditional laboratory IDT strength testing, this study derived an analytical equation based on the Hondros solution to compute the horizontal strain rate from the applied vertical displacement rate. Finally, the critical cracking temperature is determined by coupling the thermal stress and strength profiles. Using the procedure presented in this paper, the critical cracking temperatures of four AC mixtures were predicted from BBR and IDT data. Their actual critical cracking temperatures were measured using thermal stress restrained specimen test performed in the laboratory to validate the method. The predicted critical cracking temperatures are found to be very close to the laboratory measured values. The developed procedure has substantial practical and technical importance in predicting the critical cracking temperature of AC because it utilizes widely available BBR and IDT tests.
      Citation: Transportation Research Record
      PubDate: 2021-07-20T06:33:10Z
      DOI: 10.1177/03611981211023764
       
  • Effect of Raw Sugarcane Bagasse Ash as Sand Replacement on the
           Fiber-Bridging Properties of Engineered Cementitious Composites

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      Authors: Sujata Subedi, Gabriel A. Arce, Marwa M. Hassan, Michele Barbato, Louay N. Mohammad
      Abstract: Transportation Research Record, Ahead of Print.
      The use of raw sugarcane bagasse ash (SCBA) as sand replacement in the production of engineered cementitious composites (ECCs) can improve its cost-effectiveness and practicality. A recent study by the authors showed that the use of raw SCBA as a replacement to sand in ECC mixtures substantially enhances the tensile ductility and provides mild improvements in tensile strength; however, it also indicated a need to further elucidate the mechanisms producing such improvements. Therefore, the present study examined the effects of raw SCBA as a sand replacement in ECC’s fundamental fiber-bridging relationship, [math], through single crack tensile test (SCTT) using 1% polyvinyl alcohol (PVA) fiber volume fraction. The PVA fiber volume fraction was reduced from 1.5% in the previous study to 1% in this study to ensure that a single crack was produced, which is a necessary condition to obtain the fundamental [math] relationship. A total of five mixtures were evaluated at different replacement levels of sand with raw SCBA (i.e., 0%, 25%, 50%, 75%, and 100%). SCTT results revealed that raw SCBA produced minor effects on the fiber-bridging capacity but significantly increased the complementary energy ( [math]). A positive correlation was observed between the pseudo strain-hardening (PSH) strength index and raw SCBA content. Since the PSH strength index was higher than the recommended value (i.e., 1.3) for robust PSH behavior, it was concluded that the main factor contributing to tensile ductility enhancements was the increase in the PSH energy index resulting from the notable increase of [math] and potential decrease in matrix fracture toughness.
      Citation: Transportation Research Record
      PubDate: 2021-07-20T06:31:08Z
      DOI: 10.1177/03611981211023762
       
  • Utilization of Cold Central Plant Recycled Asphalt in Long-Life Flexible
           Pavements

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      Authors: David H. Timm, Brian K. Diefenderfer, Benjamin F. Bowers, Gerardo Flintsch
      Abstract: Transportation Research Record, Ahead of Print.
      Long-life flexible pavements are well documented and used widely across the U.S. Found in every climate zone and traffic classification, long-life pavements do not experience deep structural distresses such as bottom-up fatigue cracking or substructure rutting. Full-scale test sections, built in 2003 at the National Center for Asphalt Technology (NCAT) Test Track, provided the basis for an optimized design approach that utilizes strain distributions for long-life thickness design. These sections, containing only virgin materials, were subjected to 30 million standard axle loadings with excellent performance in terms of rutting, cracking, and roughness. In 2012, three new sections were built at the Test Track using cold central plant recycled asphalt materials as the base layer. These layers, made from nearly 100% reclaimed asphalt pavement (RAP), supported hot mix asphalt layers that also included RAP with one section featuring in-place stabilization of the existing aggregate base. This paper provides a direct comparison between the sets of sections to compare and contrast their performance histories and structural characterization, and consider their economic and environmental impacts. None of the recycled sections are exhibiting any surface deterioration, despite heavy trafficking, and the section with a stabilized base is exhibiting lower strains than established long-life pavement thresholds. The economic analysis suggested that the recycled sections can deliver similar performance at a lower average structure normalized section cost than the non-recycled sections. Furthermore, the section with the stabilized base and 76% recycled material is likely a long-life pavement and can potentially outperform the sections with no recycled content.
      Citation: Transportation Research Record
      PubDate: 2021-07-20T06:29:49Z
      DOI: 10.1177/03611981211023760
       
  • Application of Data-Driven Safety Analysis to Support Port Authority
           Investment Decisions for Converting Conventional Toll Plazas to Open-Road
           Tolling

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      Authors: Frank Gross, Scott Himes, Rizwan Baig, Benjamin Szeto
      Abstract: Transportation Research Record, Ahead of Print.
      Capital improvement projects have the potential to enhance safety, mobility, and environmental quality, but these projects can include considerable costs. When making investment decisions, it is important for agencies to understand the costs in relation to the potential benefits. For several years, transportation agencies have analyzed and quantified the operational and environmental impacts of proposed projects. More recently, the first edition of the Highway Safety Manual and related resources have provided agencies with the tools needed to quantify the safety impacts of proposed projects. This paper describes the use of data-driven safety analysis methods by the Port Authority of New York and New Jersey to quantify the direct and indirect safety benefits of the proposed conversion of conventional toll plazas to open-road tolling. The analysis estimated the direct safety benefits (i.e., change in the number of crashes) and indirect safety benefits (i.e., change in travel time, fuel costs, and emissions resulting from crashes). These changes were converted to dollars, providing an estimate of the present value benefits based on the expected service life of the enhanced toll systems. The analysis indicated the conversions could reduce crashes by more than 900 annually, including the prevention of nearly 30 injury crashes annually. Indirect safety benefits included more than 200,000 h in reduced travel time, 335,000 gal of fuel saved, and nearly 3,000 metric tons of CO2 reduced annually. Over the 15-year life cycle, this would provide an estimated benefit of more than $200 million from crashes directly and $367 million in indirect benefits.
      Citation: Transportation Research Record
      PubDate: 2021-07-20T06:28:29Z
      DOI: 10.1177/03611981211021855
       
  • Land-Use Regression of Long-Term Transportation Data on Metabolic Syndrome
           Risk Factors in Low-Income Communities

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      Authors: Juan Aguilera, Soyoung Jeon, Mayra Chavez, Gabriel Ibarra-Mejia, Joao Ferreira-Pinto, Leah D. Whigham, Wen-Whai Li
      Abstract: Transportation Research Record, Ahead of Print.
      Traffic-related air pollution has been associated with adverse cardiovascular health effects in near-road residents. Transportation parameters are important surrogate variables to determine spatial variation of air pollution and consequential health outcomes. We used land-use regression models to explore associations between cardiovascular (metabolic syndrome [MetS]) health outcomes collected from a sample of low-income participants (N = 4,959) and transportation parameters within a defined impact zone of a participant’s residence. We hypothesize cardiovascular risk factors are associated with spatially distributed transportation parameters and land-use data. MetS risk factors (waist circumference, blood pressure, triglycerides, HDL-cholesterol, and glucose) were obtained from 4,945 participants between 2014 and 2020 across the city of El Paso, Texas. Traffic-related and land-use variables were acquired from the El Paso MPO and the U.S. Census Bureau within two impact zones of 500 m and 1,000 m radius, centered at each participant resident’s home latitude and longitude coordinates using GIS. The increase in street length within 500 m radius was found to associate with increases in BMI, waist circumference, triglycerides, and glucose (p 
      Citation: Transportation Research Record
      PubDate: 2021-07-20T06:24:28Z
      DOI: 10.1177/03611981211021853
       
  • Assessment of AASHTO Load-Spreading Method for Buried Culverts and
           Proposed Improvement

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      Authors: Michael G. Katona
      Abstract: Transportation Research Record, Ahead of Print.
      AASHTO’s ad hoc method (AAM) for predicting free-field soil stress under a rectangular loading area is a simple and very useful tool for the analysis of buried culverts subject to vehicular wheel loads. AAM assumes the surface load spreads with soil depth into an ever-increasing rectangular area whose dimensions are controlled by a constant spread angle θ usually taken as 30°, denoted as AAM-30°. Both simplified and comprehensive culvert analysis procedures utilize AAM predictions for adjusting pressure distributions acting on the culvert periphery. Also, AAM-30° is routinely used to determine the two-wheel soil interaction depth, in which the combined effect of both axial wheels need to be considered. To date, a thorough accuracy analysis of AAM-30° has not been published in the open literature. This paper provides a unique and rigorous evaluation of AAM-30° using an exact solution from an elasticity-based model (EBM) of a homogeneous half-space with rectangular surface load. One key discovery is the depth parameter called y*, which is the soil depth at which AAM-30° peak-stress prediction exactly matches the exact EBM solution. Moreover, it is shown that y* may be determined by a simple, yet accurate formula that only depends on the square root of the load area. However, the investigation reveals that AAM-30° significantly underestimates peak stress in the shallow-depth zone 0 
      Citation: Transportation Research Record
      PubDate: 2021-07-20T06:22:28Z
      DOI: 10.1177/03611981211021546
       
  • Increasing Transparency and Feasibility of Auto Accessibility for Project
           Prioritization

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      Authors: Richard A. Boateng, John S. Miller
      Abstract: Transportation Research Record, Ahead of Print.
      Accessibility, the number of time-decayed jobs available to each zone within a region, can help prioritize candidate transportation investments. This paper demonstrates how to compute auto accessibility using commonly available resources and identifies strategies needed to render calculations feasible and transparent. (The scope excludes transit and pedestrian impacts.)For the first objective, computational solutions included developing a semi-automated method to import legacy transportation networks, automating turn prohibitions, and using an algorithm to check for inconsistently formed service areas that sometimes occur in a random fashion with geographic information system software. Failure to exercise quality control using these approaches gives erroneous results: not solving the problem of inconsistently formed service areas led to a region within 50 mi of a 1-mi corridor (where improvements are proposed) having an accessibility almost 40 times higher than the correct value. For the second objective, the influence area (i.e., catchment radius) mattered most: for one project, the forecast accessibility improvement dropped by 80% when an area within 45 mi of the project, rather than an area within 15 mi, was the basis of the analysis. Other decisions affected forecast accessibility improvement less: the choice of the number of centroid connectors affected forecasts by an average of 23% (with a 10-mi influence area). Choosing to eliminate negative net accessibility contributions, attributed to geometric approximations in the software, affected forecasts by less than 21% (35-mi influence area or smaller). Ranking five proposed investments in relation to their forecast accessibility benefit demonstrated the importance of documenting users’ computational choices.
      Citation: Transportation Research Record
      PubDate: 2021-07-20T06:21:07Z
      DOI: 10.1177/03611981211021545
       
  • Database Design and Integration Framework for Risk Management for State
           Highway Agencies

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      Authors: Inya Nlenanya, Omar Smadi
      Abstract: Transportation Research Record, Ahead of Print.
      Risk-based transportation asset management program (TAMP) gives transportation agencies the ability to have a mechanism for documenting and measuring risks to their operations, as this will help drive the potential mitigation activities. The monitoring and updating of the risk management process is essential to TAMP as it will ensure that the financial plan and investment strategy components of the TAMP are suitable to ensure that agencies continue to fulfill their primary responsibilities. However, a review of the initial TAMP documents submitted by U.S. transportation agencies showed that although risks are acknowledged, there does not exist a clear line of sight between risk management and agencies’ programming. This is the result of a lack of cross-asset risk integration. As a result, the paper proposes a data integration framework for developing a cross-asset comprehensive database for risk management that integrates many of the common risks that state highway agencies have identified in the initial TAMP documents. In addition, the paper proposes modifications to the risk identification methodology that leverage the collaborative aspects of risk management to quantify risk in monetary terms.
      Citation: Transportation Research Record
      PubDate: 2021-07-20T06:19:47Z
      DOI: 10.1177/03611981211020004
       
  • Thermomechanical Coupling of a Hyper-viscoelastic Truck Tire and a
           Pavement Layer and its Impact on Three-dimensional Contact Stresses

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      Authors: Angeli Jayme, Imad L. Al-Qadi
      Abstract: Transportation Research Record, Ahead of Print.
      A thermomechanical coupling between a hyper-viscoelastic tire and a representative pavement layer was conducted to assess the effect of various temperature profiles on the mechanical behavior of a rolling truck tire. The two deformable bodies, namely the tire and pavement layer, were subjected to steady-state-uniform and non-uniform temperature profiles to identify the significance of considering temperature as a variable in contact-stress prediction. A myriad of ambient, internal air, and pavement-surface conditions were simulated, along with combinations of applied tire load, tire-inflation pressure, and traveling speed. Analogous to winter, the low temperature profiles induced a smaller tire-pavement contact area that resulted in stress localization. On the other hand, under high temperature conditions during the summer, higher tire deformation resulted in lower contact-stress magnitudes owing to an increase in the tire-pavement contact area. In both conditions, vertical and longitudinal contact stresses are impacted, while transverse contact stresses are relatively less affected. This behavior, however, may change under a non-free-rolling condition, such as braking, accelerating, and cornering. By incorporating temperature into the tire-pavement interaction model, changes in the magnitude and distribution of the three-dimensional contact stresses were manifested. This would have a direct implication on the rolling resistance and near-surface behavior of flexible pavements.
      Citation: Transportation Research Record
      PubDate: 2021-07-20T06:17:47Z
      DOI: 10.1177/03611981211017140
       
  • How Do Shared Dockless E-Scooter Services Affect Mobility Practices in
           Paris' A Survey-Based Estimation of Modal Shift

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      Authors: Camille Krier, Julie Chrétien, Marion Lagadic, Nicolas Louvet
      Abstract: Transportation Research Record, Ahead of Print.
      Shared dockless e-scooters were first launched in Paris in the summer of 2018. These services were met with mixed reception: although some praised them for offering a new mobility solution to urban dwellers, others soon questioned their environmental impact. An emerging body of literature using lifecycle analysis shows that shared e-scooters are more pollutant than walking, cycling, and public transportation, but remain preferable to cars. To better grasp the impacts of dockless e-scooters, it is therefore necessary to identify which modes of transportation they replace. As mobility highly depends on local context, city-specific data are needed. Although modal change data from cities in North America and New Zealand are available, there is no similar information from dense European cities. Using quantitative survey data collected from shared e-scooter users in Paris, the present research offers novel data on modal shift toward dockless e-scooters in the French capital. Results show that for their last trip riding a shared e-scooter, most users would have walked or used public transportation had e-scooters not been an option, and only a limited share of them would have used a car. However, the overall impact of e-scooters on walking and public transportation use remains limited and they display a significant complementarity with public transportation. Such city-specific data on e-scooter use and impacts provide valuable inputs for local public authorities to implement efficient and tailored regulatory measures, so as to include these services in sustainable mobility policies.
      Citation: Transportation Research Record
      PubDate: 2021-07-20T06:16:36Z
      DOI: 10.1177/03611981211017133
       
  • Two-Lane Highway Crash Severities: Correlated Random Parameters Modeling
           Versus Incorporating Interaction Effects

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      Authors: Ahmed Farid, Anas Alrejjal, Khaled Ksaibati
      Abstract: Transportation Research Record, Ahead of Print.
      Two-lane highways represent the majority of highways in the U.S. and their safety is of crucial concern. Even though road safety researchers intensively evaluated two-lane highway safety, past studies were challenged by a methodological hindrance, namely that of correlated random parameters (CRP) modeling methods. Random parameters models capture unobserved heterogeneity effects of crash contributing factors, while CRP models offer the additional benefit of capturing correlations among variables inducing such unobserved heterogeneity effects. However, CRP models do not permit specifying pairs of regressors, with statistically insignificant correlations, to be uncorrelated. In this research, it was demonstrated that the conventional uncorrelated random parameters ordinal probit (URPOP) structure with interaction effects outperformed the correlated random parameters ordinal probit (CRPOP) structure when modeling injury severity risks of two-lane highway crashes in Wyoming. As per the former model’s results, speeding, head-on collisions, sideswipe opposite-direction collisions, intersecting-direction collisions, motorcycle involvement, impaired driving, distracted driving, the interaction effect of speeding with motorcycle involvement, that of head-on collisions with impaired driving, and that of head-on collisions with commercial vehicle involvement all raised the likelihood of sustaining severe injuries. Conversely, leaving the crash scene, proper seat belt use, wet road surfaces, and the interaction effect of impaired driving with motorcycle involvement alleviated the risk of incurring severe injuries. The superiority of the proposed model and its reduced computation time warrant its recommendation for implementation in future studies. Also, from a practical perspective, safety mitigation measures are suggested based on this research’s findings.
      Citation: Transportation Research Record
      PubDate: 2021-07-17T06:38:01Z
      DOI: 10.1177/03611981211018473
       
  • A Deep Learning Model for Off-Ramp Hourly Traffic Volume Estimation

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      Authors: Amir Nohekhan, Sara Zahedian, Ali Haghani
      Abstract: Transportation Research Record, Ahead of Print.
      This paper addresses estimation of traffic volume of freeway off-ramps. Freeways are the transportation network’s main corridors, serving a large portion of the traffic volume. This traffic passes into the lower-level roads through off-ramps. Therefore, the traffic condition of the off-ramps is an essential factor affecting the operation of the transportation network. The continuous collection of volume data is impractical, and transportation authorities install vehicle detectors permanently on only a few off-ramps and temporarily (e.g., a week) on some others. Thus, traffic volume is the most challenging to estimate among various traffic measures. Moreover, the existing literature on volume estimation is mainly concerned with evaluating traffic on the main road segments. However, the distinct characteristics of the connection links, such as off-ramps, demands specified modeling. This study estimates the hourly traffic volume of off-ramps using a deep learning model. It evaluates the advantages of inputting the connected lower-level road features to the model, and explores various detector installation strategies on the model training process. The primary data sources are volume counts, probe speeds, and road segment infrastructure characteristics. The model results indicate that the incorporation of traffic flow characteristics and infrastructure attributes of the lower-level road connected to the freeway significantly improves the accuracy of estimation off-ramp traffic volume. Further, analysis illustrated that the model trained with data from temporarily installed detectors on all interchanges outperformed models trained with permanently installed detectors on 90% of the interchanges, indicating the model’s ability in extracting temporal correlations significantly more than spatial correlations.
      Citation: Transportation Research Record
      PubDate: 2021-07-17T06:29:00Z
      DOI: 10.1177/03611981211027151
       
  • Examining Customers’ Critical Acceptance Factors toward Ridepooling
           Services

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      Authors: Oliver Werth, Marc-Oliver Sonneberg, Max Leyerer, Michael H. Breitner
      Abstract: Transportation Research Record, Ahead of Print.
      Ridepooling is a new mobility service mainly for people in cities and urban areas. By matching the routes of customers with similar start and end points while driving in an optimally pooled manner, meaningful reductions in road traffic and related emissions can be achieved. Such services must meet customers’ demands appropriately to achieve sustainable customer acceptance. Service providers face diverse customer expectations and prejudices that differ from those toward existing transportation modes. Today, most ridepooling trips are conducted with only one customer, confirming impressions of non-optimal operation. Using a survey-based approach, possible relevant constructs for the acceptance of and intention to use ridepooling services are analyzed. Testing constructs from the Unified Theory of Acceptance and Use of Technology 2 and environmental awareness, partial least squares analysis was performed with the software SmartPLS to investigate a dataset of 224 respondents. Results suggest that attitude toward use, perceived usefulness, and performance expectancy have an influence on the behavioral intention to use ridepooling services. In contrast, environmental awareness, price value, and effort expectancy do not have such an influence. The study expands the literature about customer acceptance of ridepooling service as well as new mobility services in general. Further, the paper provides research implications and recommendations for the development and implementation of the ridepooling concept for service providers.
      Citation: Transportation Research Record
      PubDate: 2021-07-17T06:27:39Z
      DOI: 10.1177/03611981211026304
       
  • Optimizing Budget Allocation for Incentive-Based Active Travel Demand
           Management Solutions

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      Authors: Lin Xiao, Jiyan Wu, Ye Tian, Jian Sun, Chen Lei, Yiduo Fang
      Abstract: Transportation Research Record, Ahead of Print.
      Incentive-based travel demand management (IBTDM) strategies utilize rewards to redistribute travel demand across space and time. Such congestion-alleviation solutions are usually managed by small private companies with constraint budgets. Aside from spending money on incentives, running promotional campaigns to achieve the gains in market share is essential for maintaining the financial health of IBTDM programs. Therefore, the budget allocation between the two counterparts—incentive and marketing expenditure—needs to be wisely determined. Based on the bottleneck model, this paper proposes an optimal budget allocation scheme considering the impact of a budget constraint and market penetration. It was found that the constraint budget should be prioritized to attract those with lower marketing costs in general. In situations with an insufficient budget and when marketing costs were lower for attracting lower-income individuals, IBTDM decision-makers should focus on those lower-income individuals at first. This mitigates inequity issues to some extent. Therefore, policy makers or planners should pay more attention to marketing cost when developing a marketing plan and try to reduce marketing cost to make full use of incentive budget.
      Citation: Transportation Research Record
      PubDate: 2021-07-17T06:26:43Z
      DOI: 10.1177/03611981211025512
       
  • Queue Analysis at Work Zones from Field-Collected Data

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      Authors: Julius Codjoe, Raju Thapa, Elisabeta Mitran
      Abstract: Transportation Research Record, Ahead of Print.
      Estimation of the capacity of work zones is vital to manage the possibility of traffic flows exceeding capacity and resulting in unbearable queues during work zone lane closures. A plethora of research papers have studied several ways to estimate work zone capacity, with the Highway Capacity Manual (HCM) having its own methodology to estimate capacity based on various site characteristics. However, HCM always recommends validating its model with local data to reflect the actual driving behavior of the region. This study considered work zone capacity as a function of queue discharge rate (QDR), defined as the 15-min average flow rate immediately after breakdown, also known as postbreakdown flow rate. By collecting data from 10 different work zones within the state of Louisiana, the study estimated QDR and its corresponding duration at breakdowns. An average QDR of 1,664 pcphpl and an associated queue of 120 min average duration was found. Analysis of variance showed that average QDRs across all sites were not significantly different. The QDR prediction model revealed that a closed right lane and a work zone on linear roadways significantly increased the discharge rate. However, the presence of nearby exit ramps, daytime scenarios, and an increase in the speed ratio and truck percentages were found to decrease the discharge rate. A separate model for the duration of queue or breakdown found the time of day, change in the speed ratio, presence of entry ramp, location of work zones, and annual average daily traffic of the roadway to be significant variables.
      Citation: Transportation Research Record
      PubDate: 2021-07-17T06:25:19Z
      DOI: 10.1177/03611981211025284
       
  • Benefits of Compiling and Analyzing Hydraulic-Design Data for Bridges

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      Authors: Stephen T. Benedict, Thomas P. Knight
      Abstract: Transportation Research Record, Ahead of Print.
      The hydraulic design of bridges is a discipline that requires a strong measure of engineering judgment. Developing good engineering judgment can take years of experience, and generally increases one project at a time. A supplemental tool that can promote the development of engineering knowledge and judgment is to compile, analyze, and graphically present hydraulic data associated with stream and bridge-design characteristics from previously analyzed bridges. If the data set is sufficiently large, graphs developed from such an effort can provide the engineer with an enhanced picture of stream and bridge-design characteristics, helping them further develop their engineering knowledge and judgment. Furthermore, such graphs can function as project scoping tools and hydraulic-design review tools. Using selected data from approximately 300 bridge-scour studies in South Carolina, previously conducted by the U.S. Geological Survey, and limited hydraulic bridge-design data for approximately 200 bridges in South Carolina, trends in stream and bridge-hydraulic characteristics were evaluated including channel width, floodplain width, flood flow depths, stream slopes, bridge backwater, bridge flow velocity, and bridge lengths. Selected relationships are presented in this paper and should serve as a valuable tool for better understanding stream and bridge-hydraulic characteristics in South Carolina.
      Citation: Transportation Research Record
      PubDate: 2021-07-17T06:24:20Z
      DOI: 10.1177/03611981211023757
       
  • Evaluation of Asphalt Mixture Performance Using Cracking and Durability
           Tests at a Full-Scale Pavement Facility

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      Authors: Amir Golalipour, Varun Veginati, David J. Mensching
      Abstract: Transportation Research Record, Ahead of Print.
      In the asphalt materials community, the most critical research need is centered around a paradigm shift in mixture design from the volumetric process of the previous 20-plus years to an optimization procedure based on laboratory-measured mechanical properties that should lead to an increase in long-term pavement performance. This study is focused on advancing the state of understanding with respect to the value of intermediate temperature cracking tests, which may be included in a balanced mix design. The materials included are plant-mixed, laboratory-compacted specimens reheated from the 2013 Federal Highway Administration’s (FHWA’s) Accelerated Loading Facility (ALF) study on reclaimed asphalt pavement/reclaimed asphalt shingle (RAP/RAS) materials. Six commonly discussed intermediate temperature (cracking and durability) performance testing (i.e., Asphalt Mixture Performance Tester [AMPT] Cyclic Fatigue, Cantabro, Illinois Flexibility Index Test [I-FIT], Indirect Tensile Cracking [ITC, also known as IDEAL-CT], Indirect Tensile Nflex, and Texas Overlay Test) were selected for use in this study based on input from stakeholders. Test results were analyzed to compare differences between the cracking tests. In addition, statistical analyses were conducted to assess the separation among materials (lanes) for each performance test. Cyclic fatigue and IDEAL-CT tests showed the most promising results. The ranking from these two tests’ index parameters matched closely with ALF field performance. Furthermore, both showed reasonable variability of test data and they were successful in differentiating between different materials.
      Citation: Transportation Research Record
      PubDate: 2021-07-17T06:22:40Z
      DOI: 10.1177/03611981211021856
       
  • Bike Count Forecast Model with Multimodal Network Connectivity Measures

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      Authors: Bingqing Liu, Divya Bade, Joseph Y. J. Chow
      Abstract: Transportation Research Record, Ahead of Print.
      With the rise of cycling as a mode choice for commuting and short-distance delivery, as well as policy objectives encouraging this trend, bike count models are increasingly critical to transportation planning and investment. Studies have found that network connectivity plays a role in such models, but there remains a lack of measure for the connectivity of a link in a multimodal trip context. This study proposes a connectivity measure that captures the importance of a link in connecting the origins of cyclists and nearby subway stations, and incorporates it in a negative binomial regression model to forecast bike counts at links. Representative bike trips are generated with regard to bike-friendliness using the New York City transit trip planner and used to determine the deviation from the shortest path via the designated link. The measure is shown to improve model fitness with a significance level within 10%. Insights are also drawn for income levels, bike lanes, subway station availability, and average commute time of travelers.
      Citation: Transportation Research Record
      PubDate: 2021-07-17T06:21:21Z
      DOI: 10.1177/03611981211021849
       
  • Emergence of 4-D System Fundamental Diagram in Urban Air Mobility Traffic
           Flow

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      Authors: Christopher Cummings, Hani Mahmassani
      Abstract: Transportation Research Record, Ahead of Print.
      Urban air mobility (UAM) is an emerging mode that promises to provide relief to congested urban streets. UAM relies on airspace, however, which is an exhaustible resource considering minimum aircraft separation requirements. In light of these requirements and UAM vehicle attributes, a simulation is developed to explore UAM traffic flows and congestion development. A decentralized conflict resolution scheme is employed in the form of a non-linear program (NLP) to offer improved flexibility in detours relative to past aircraft simulations. An expansion of Edie’s definitions of density and flow rate are used in conjunction with average speed to explore the relationships between traffic flow characteristics. The results find that UAM traffic flows emulate those of other modes, by following the familiar traffic patterns of build-up and breakdown captured in the macroscopic fundamental diagram. These findings also suggest the presence of a capacity of airspace that should be carefully managed by operators to achieve optimal system performance. The relationships established in this study highlight issues that UAM operators and aviation planners may face and could be used to improve the vehicle traffic modeling of other UAM models.
      Citation: Transportation Research Record
      PubDate: 2021-07-17T06:18:40Z
      DOI: 10.1177/03611981211020005
       
  • Assessment of Operational Effectiveness of SynchroGreen Adaptive Signal
           Control System in South Carolina

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      Authors: Weimin Jin, M Sabbir Salek, Mashrur Chowdhury, Mohammad Torkjazi, Nathan Huynh, Patrick Gerard
      Abstract: Transportation Research Record, Ahead of Print.
      An adaptive signal control system (ASCS) can adjust signal timings in real time based on traffic demands. The operational benefits of ASCS vary depending on the type of ASCS, corridor characteristics, and geographical area. This paper evaluates the operational performance of 11 ASCS corridors located throughout South Carolina. These corridors are operated using SynchroGreen, one of several types of ASCS, developed by TrafficWare. Based on the operational analysis, it is found that when SynchroGreen is operational, it reduces the travel time on the corridor by an average of 6.4% and improves travel time reliability by an average of 31.4% compared with when the conventional traffic signal control system (e.g., pre-timed and actuated signal control) is operational. SynchroGreen reduces travel time on a corridor on average 61% of the time during a day and on average 77% of the time during peak periods. Additionally, SynchroGreen improves travel time reliability on average 53% of the time during a day and on average 52% of the time during peak periods. The operational effectiveness of SynchroGreen in reducing travel time and improving travel time reliability is consistent in both directions on an hourly basis for eight corridors and five corridors, respectively. Lastly, SynchroGreen is found to produce greater operational benefits by reducing travel time if the average speed of a corridor is lower than or equal to 35 mph and the number of signals on a corridor is more than 10.
      Citation: Transportation Research Record
      PubDate: 2021-07-17T06:14:20Z
      DOI: 10.1177/03611981211019745
       
  • Smart Airport: Evaluation of Performance Standards and Technologies for a
           Smart Logistics Zone

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      Authors: Elifcan Göçmen
      Abstract: Transportation Research Record, Ahead of Print.
      Owing to the current context of Industry 4.0, the importance of smart technologies in airport systems have increased substantially. State-of-art applications for transportation planning incorporating baggage services, routing, security, and safety are an evolving domain for both practitioners and researchers dealing with aviation applications. In this context, this paper seeks to answer these questions: Which standards are aimed at a smart airport to make the transportation planning sound' Which propositions are made based on the obtained prioritized standards' This study deals with standards including Environmental Effects, Docking & Navigation, Object Detection & Protection, Communications & Integration, and Terminology using a practical decision support system based on an analytical hierarchy process (AHP) and fuzzy inference system (FIS). Computational results reveal that the Object Detection & Protection standard has an effect on a safe and smart system. To give an overview of this standard for a smart logistics zone (SLZ), an architecture of autonomous robot units and a baggage handling system is proposed in this study. The suggested approach analyzes the obstacle photos obtained by cameras and allows the end-user to control the calculations visually. This research could provide advice to airport planners about smart policies and improving operations.
      Citation: Transportation Research Record
      PubDate: 2021-07-17T06:13:00Z
      DOI: 10.1177/03611981211019740
       
  • Developing Mixed Traffic Equivalency Factors to Estimate Saturation Flow
           at Urban Signalized Intersections

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      Authors: Pinakin N. Patel, Ashish Dhamaniya
      Abstract: Transportation Research Record, Ahead of Print.
      This study proposes a time occupancy approach to estimate passenger car units (PCUs) at urban signalized intersections with different interaction levels between vehicles under saturated green time conditions. The study shows a variation in PCUs with varied traffic and geometric conditions. Traffic data have been collected through videography techniques at signalized intersections in three metropolitan cities in India. Traffic flow discharge and clearance time of different vehicular categories have been extracted from the video during the saturated green time. The observed ranges of dynamic PCU values for two-wheelers, three-wheelers, big cars, light commercial vehicles, and heavy vehicles are 0.12 to 0.32, 0.45 to 0.80, 1.40 to 1.80, 1.60 to 2.20, and 3.50 to 6.50, respectively. Regression-based PCU models have been developed for each vehicle category to address the variation of individual vehicle PCUs with traffic compositions and flow rates. The model analysis shows that traffic compositions and flow rates are significantly affecting the PCU values. The PCU is a complex parameter requiring several field attributes. Therefore, to overcome the complexity of estimating PCUs, a concept of flow equivalency factor (FEF) has been proposed based on the estimated PCUs. The FEF can directly convert the mixed motorized vehicular flow into an equivalent standard passenger car flow without actually making use of different vehicles’ PCU factors. All the developed models have been validated for field conditions and results are found promising with field data. The developed approach can be used effectively for developing countries with a mixed traffic stream.
      Citation: Transportation Research Record
      PubDate: 2021-07-17T06:11:41Z
      DOI: 10.1177/03611981211018694
       
  • Building Information Modeling for Bridges and Structures: Outcomes and
           Lessons Learned from the Steel Bridge Industry

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      Authors: Aaron Costin, Hanjin Hu, Ronald Medlock
      Abstract: Transportation Research Record, Ahead of Print.
      The recent push to adopt building information modeling (BIM) for bridges and structures in the transportation industry has encountered major barriers owing to the lack of standardization. Unlike the building industry that has the National BIM Standard®–United States (NBIMS-US™) as a formal open platform standard and guide for the development of interoperable BIM software, the transportation industry does not currently have a similar open platform standard to enable the creation of interoperable BIM software to serve the needs of transportation stakeholders. The purpose of this paper is to present the findings of the research for one of the first use cases and development of data exchange requirements and model view definitions in adopting the open platform NBIMS-US applied to bridges and structures for the U.S. transportation industry. A subcommittee of the American Association of State Highway and Transportation Officials and the National Steel Bridge Alliance Steel Bridge Collaboration was formed to conduct a pilot study into the creation of information delivery manuals (IDMs) for steel bridges. This study served as pilot for the development of future IDMs in the transportation industry. As a result, the current IDM for Steel Bridge Detailing and Fabrication serves as the starting point of TPF-5(372) BIM for Bridges and Structures development of the Design to Fabrication model view definition. Finally, this study provided the outcomes and recommendations needed to expedite the development of IDMs for other use cases in the bridge and transportation industry.
      Citation: Transportation Research Record
      PubDate: 2021-07-17T06:10:20Z
      DOI: 10.1177/03611981211018691
       
  • Crowd-in Effect of Highway Capital on Private Investment in the United
           States

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      Authors: Bingxin Yu, Valentin Vulov
      Abstract: Transportation Research Record, Ahead of Print.
      This paper examines the impacts of public transportation infrastructure investment on private investment and whether public infrastructure investment tends to “crowd in” or “crowd out” private investment. “Crowding in” refers to situations where public investment encourages private sector investment, whereas “crowding out” refers to situations where public investment discourages private sector investment. This analysis applies the vector autoregression (VAR) methodology for an empirical study. Using national-level annual data from 1947 to 2017 in the United States, estimation results suggest that public investment in highways tends to crowd in private investment after an initial and temporary crowding-out effect. Most of the positive impacts on private investment accrue within 3 years after the initial public investment. The incremental impact diminishes almost completely after roughly 10 years. Alternative model specifications and sensitivity analyses further confirm the robustness of the model specification by yielding consistent and positive crowd-in effects within the first 3 to 5 years after the public investment.
      Citation: Transportation Research Record
      PubDate: 2021-07-17T06:05:20Z
      DOI: 10.1177/03611981211017910
       
  • Benefits Derived from Arrival Management and Wake Turbulence
           Re-Categorization in China

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      Authors: Zihan Peng, Junfeng Zhang, Tong Xiang, Bin Wang, Haipeng Guo
      Abstract: Transportation Research Record, Ahead of Print.
      Air traffic administration requires evidence when promoting new technology or a new concept of operation. Therefore, when decision support tools are applied, it is necessary to analyze the costs and benefits quantitatively. This paper focuses on the evaluation of Key Performance Indicators (KPIs) correlated with the improvement of arrival operations after the implementation of the Arrival Management (AMAN) system and Wake Turbulence Re-categorization in China (RECAT-CN). Firstly, we give an overview of the implementation of the AMAN system and RECAT in China. Secondly, the KPIs related to the arrival operation are established according to the characteristics of AMAN and RECAT-CN, based on the existing KPI systems in the field of Air Traffic Management (ATM). The proposed KPIs are: airport acceptance rate; final approach interval; flight time within the terminal area (TMA); and taxi-in time. Thirdly, arrival operation within the TMA around Guangzhou International Airport is used as an example to carry out the quantitative analysis. The region and time range were defined for the performance comparison, and external factors were also examined. Finally, using descriptive and inferential statistics, the proposed KPIs’ comparison results are presented and visualized. Such results indicate a significant improvement in arrival operation with the AMAN system and RECAT-CN at Guangzhou International Airport.
      Citation: Transportation Research Record
      PubDate: 2021-07-17T06:02:00Z
      DOI: 10.1177/03611981211017898
       
  • Relationship between Programmed Heavy Vehicle Inspections and Traffic
           Safety

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      Authors: Behrang Assemi, Mark Hickman, Alexander Paz
      Abstract: Transportation Research Record, Ahead of Print.
      Heavy vehicle crashes incur significant economic and social costs. Although most crashes are considered to be related to driver error, the effects of vehicle defects are major in many crashes. Therefore, various vehicle inspections including Queensland’s Certificate of Inspection (COI) scheme have been implemented to improve the safety of heavy vehicles. This study analyzes the trends of heavy vehicle crashes and their relationships with COI results. Longitudinal data provided by Queensland’s Department of Transport and Main Roads for the period of June 2009 through December 2013 were used to perform the analyses. The data include 474,640 programmed inspections and 2,274 crashes in which heavy vehicles were involved. The results show significant relationships between the monthly average inspection failure rate as well as the monthly average failure severity level, and the total number of heavy vehicle crashes. The results also reveal significant relationships between the monthly average inspection failure rate, average vehicle age, as well as monthly average mean maximum temperature, and the number of defect-related crashes. The implications of these results are discussed with respect to heavy vehicle safety policies.
      Citation: Transportation Research Record
      PubDate: 2021-07-17T06:01:14Z
      DOI: 10.1177/03611981211016458
       
  • Performance of Back-to-Back Geogrid Reinforced Soil Retaining Walls for
           Railways during Service

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      Authors: Guangqing Yang, Yunfei Zhao, Zhijie Wang, He Wang
      Abstract: Transportation Research Record, Ahead of Print.
      To investigate the performance of a reinforced soil retaining wall during service for a passenger-dedicated railway, long-term remote observation testing of the back-to-back geogrid reinforced retaining wall (BBGRSW) of Qing-Rong passenger-dedicated railway in Shandong Province was conducted for 60 months. The performance of the reinforced retaining wall was investigated after construction, and the lateral earth pressure of the reinforced soil wall was analyzed. The vertical stress on the wall and tension on the geogrid were measured using pressure cells and flexible deformation gauges, thereby resulting in the distribution of data and changes in the service period. The test results show that the pressure and deformation of the wall are almost stable. It was determined that the lateral earth pressure on the back of the wall panel was approximately 119.2% of the completion time during the 60 months after construction. The vertical stress on the reinforced soil retaining wall remained approximately stable 60 months post-construction. The maximum strain of the measured geogrids accounted for less than 30% of the peak strain. Moreover, the deformation of the wall was relatively small, which indicated that both sides of the wall remained in good condition. These research results can serve as a reference for the design optimization of reinforced soil retaining walls for high-speed railways.
      Citation: Transportation Research Record
      PubDate: 2021-07-16T10:20:02Z
      DOI: 10.1177/03611981211024238
       
  • Automatic Traffic Queue-End Identification using Location-Based Waze User
           Reports

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      Authors: Yuandong Liu, Zhihua Zhang, Lee D. Han, Candace Brakewood
      Abstract: Transportation Research Record, Ahead of Print.
      Traffic queues, especially queues caused by non-recurrent events such as incidents, are unexpected to high-speed drivers approaching the end of queue (EOQ) and become safety concerns. Though the topic has been extensively studied, the identification of EOQ has been limited by the spatial-temporal resolution of traditional data sources. This study explores the potential of location-based crowdsourced data, specifically Waze user reports. It presents a dynamic clustering algorithm that can group the location-based reports in real time and identify the spatial-temporal extent of congestion as well as the EOQ. The algorithm is a spatial-temporal extension of the density-based spatial clustering of applications with noise (DBSCAN) algorithm for real-time streaming data with an adaptive threshold selection procedure. The proposed method was tested with 34 traffic congestion cases in the Knoxville,Tennessee area of the United States. It is demonstrated that the algorithm can effectively detect spatial-temporal extent of congestion based on Waze report clusters and identify EOQ in real-time. The Waze report-based detection are compared to the detection based on roadside sensor data. The results are promising: The EOQ identification time of Waze is similar to the EOQ detection time of traffic sensor data, with only 1.1 min difference on average. In addition, Waze generates 1.9 EOQ detection points every mile, compared to 1.8 detection points generated by traffic sensor data, suggesting the two data sources are comparable in respect of reporting frequency. The results indicate that Waze is a valuable complementary source for EOQ detection where no traffic sensors are installed.
      Citation: Transportation Research Record
      PubDate: 2021-07-16T09:30:32Z
      DOI: 10.1177/03611981211013353
       
  • Comparison of Reduced-Fare Programs for Low-Income Transit Riders

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      Authors: Wesley Darling, Emily Carpenter, Tami Johnson-Praino, Candace Brakewood, Carole Turley Voulgaris
      Abstract: Transportation Research Record, Ahead of Print.
      Means-based reduced-fare programs can help address transit rider fare equity. The objective of this study is to synthesize the current state of reduced-fare programs for low-income transit riders. The reduced-fare programs of the 50 largest transit agencies in the United States were examined and agencies with programs for low-income riders were compared based on three dimensions: eligibility and enrollment, fare media and discount pricing, and estimated transit expenditure by eligible riders. The results reveal that 17 of the 50 largest transit agencies have low-income reduced-fare programs. Of these, 14 agencies administer the programs themselves, while three use partnerships with social service organizations to administer them. Additionally, nine of the 14 agencies that administer their own programs provide a 50% discount on fares and require participants to have an income at or below 125% to 200% of the federal poverty level for eligibility. Using a method developed to evaluate the “fare burden” of transit riders with different income levels, it was determined that low-income reduced-fare program participants at the income eligibility threshold typically spend an estimated 2% to 6% of their annual income on transit, although very-low-income people may need to spend much higher shares of their incomes on transit fares. These results indicate that agencies may need to reevaluate the structure of their existing low-income reduced-fare programs and implement tiers of discounts to ensure that fare equity is being extended to all riders.
      Citation: Transportation Research Record
      PubDate: 2021-07-16T05:10:42Z
      DOI: 10.1177/03611981211017900
       
  • Safe Speed Prediction Model for Heavy Trucks on Consecutive Mountain
           Downgrade Routes Based on Energy Conservation Law

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      Authors: Menghua Yan, Jinliang Xu, Shuo Han, Fangchen Ma
      Abstract: Transportation Research Record, Ahead of Print.
      Safe vehicle speed estimation is essential for road traffic management and traffic safety. Improper truck speed on downgrades may lead to brake fade and/or failure, resulting in severe truck accidents such as runaway or out-of-control. This paper presents a model for predicting the safe speed of trucks from the perspective of preventing brake failure. The proposed model can be used to control the speed limit or as a reference for the revision of highway geometric design standards. In addition, by considering the downgrade design speeds recommended by AASHTO, the study offers an approach to deciding the downgrades that need escape ramps, those that need different speed limits, and those that may need exclusions for trucks over a certain weight. First, we simplify the downgrade driving status of a heavy truck into three types: speed control, emergency braking, and speed recovery according to the speed change status. The prediction model of the brake drum temperature with speed variables has been established in our previous study based on Newton’s energy conservation law. Finally, the boundary conditions for brake fade and failure temperature are determined. Results of parameter analysis show that the gross truck weight is the most significant variable. Other significant variables are grade, grade length, and emergency braking time. Compared with previous research results, the advantage of this method is that the permitted speed can be derived using the brake temperature prediction model supported by theory, without the need for extensive field tests.
      Citation: Transportation Research Record
      PubDate: 2021-07-15T09:21:38Z
      DOI: 10.1177/03611981211024231
       
  • Incorporating Practical Degree of Saturation in Capacity Estimation of
           On-Street, Mid-Block, Off-Line Bus Stops

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      Authors: Faheema Hisham, Jonathan M. Bunker, Ashish Bhaskar
      Abstract: Transportation Research Record, Ahead of Print.
      The effectiveness of an on-street bus facility depends on the general traffic that shares the lane used by buses. The Transit Capacity and Quality of Service Manual (TCQSM) methodology was used to estimate facility bus capacity based on critical stop operation. Hisham et al. provided an improved understanding of performance of an on-street, mid-block, off-line bus stop by relating bus stop capacity to the adjacent lane traffic flow rate. Using the TCQSM methodology, bus stop capacity was determined by adopting an estimated operation margin that relates to a design bus stop failure rate. However, failure rate is theoretically ambiguous and difficult to quantify in practice, particularly under high volume traffic conditions. In contrast, degree of saturation is a direct measure of operating conditions experienced by buses using the stop, and by the adjacent lane general traffic, so it directly affects approach delay and queuing. The aim of this study was to better understand performance at on-street, mid-block, off-line bus stops by considering degrees of saturation of loading areas and the adjacent lane rather than design failure rate according to the TCQSM methodology, and to ensure that waiting times upstream of bus stops are kept to acceptable levels by determining bus stop maximum working capacity.
      Citation: Transportation Research Record
      PubDate: 2021-07-15T09:20:18Z
      DOI: 10.1177/03611981211024155
       
  • Causal Analysis of Lateral Deviation of Flights in Terminal Airspace

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      Authors: João B. T. Szenczuk, Wallace S. S. Souza, Marcelo X. Guterres, McWillian de Oliveira, Mayara C. R. Murça, Carlos Müller
      Abstract: Transportation Research Record, Ahead of Print.
      Aircraft arrival and departure procedures are designed by air navigation service providers to enable the orderly and safe flow of air traffic. However, in actual operations, flights often deviate from standard routes, especially within terminal airspace. In this context, this paper presents an analysis of the determining factors for the lateral deviation (LD) of flight paths compared with the standard aeronautical departure and arrival procedures. For that, aircraft tracking data recorded by surveillance systems were leveraged and a linear regression model was employed to map structural and operational factors into LD. Our results indicate that LD tends to decrease with increased demand and low ceiling or visibility conditions. On the other hand, convective weather tends to increase LDs as additional holdings and rerouting may be necessary. Besides, significant levels of deviation can be associated with some specific arrival and departure procedures.
      Citation: Transportation Research Record
      PubDate: 2021-07-15T09:18:36Z
      DOI: 10.1177/03611981211020009
       
  • Development and Evaluation of Geostatistical Methods for Estimating
           Weather Related Collisions: A Large-Scale Case Study

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      Authors: Andy H. Wong, Tae J. Kwon
      Abstract: Transportation Research Record, Ahead of Print.
      Winter driving conditions pose a real hazard to road users with increased chance of collisions during inclement weather events. As such, road authorities strive to service the hazardous roads or collision hot spots by increasing road safety, mobility, and accessibility. One measure of a hot spot would be winter collision statistics. Using the ratio of winter collisions (WC) to all collisions, roads that show a high ratio of WC should be given a high priority for further diagnosis and countermeasure selection. This study presents a unique methodological framework that is built on one of the least explored yet most powerful geostatistical techniques, namely, regression kriging (RK). Unlike other variants of kriging, RK uses auxiliary variables to gain a deeper understanding of contributing factors while also utilizing the spatial autocorrelation structure for predicting WC ratios. The applicability and validity of RK for a large-scale hot spot analysis is evaluated using the northeast quarter of the State of Iowa, spanning five winter seasons from 2013/14 to 2017/18. The findings of the case study assessed via three different statistical measures (mean squared error, root mean square error, and root mean squared standardized error) suggest that RK is very effective for modeling WC ratios, thereby further supporting its robustness and feasibility for a statewide implementation.
      Citation: Transportation Research Record
      PubDate: 2021-07-15T09:16:55Z
      DOI: 10.1177/03611981211020008
       
  • Achieving Asphalt Pavement Density with Minimal Mat Defects

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      Authors: Adam J. T. Hand, Timothy Aschenbrener, Nam Tran, Fabricio Leiva
      Abstract: Transportation Research Record, Ahead of Print.
      It is well established that in-place density significantly influences asphalt pavement performance and service life. This paper discusses solutions to challenges that agencies and contractors often face when trying to achieve density requirements, or increase density, while eliminating compaction-related mat defects during the construction process. The basics of the asphalt pavement compaction processes, equipment, operations, and asphalt mixture densification are first presented, followed by information collected on a series of FHWA sponsored departments of transportation (DOTs) density demonstration projects. The authors then summarize the root causes associated with challenges in obtaining the desired density without compaction-related mat defects in a series of categories based on the DOT demonstration projects and experience assisting contractors with obtaining density on hundreds of projects. Examples are described for each category along with potential opportunities for improvements to overcome them. The demonstration projects illustrated that it is possible to make improvements when agencies and contractors embrace the idea of increasing density and reducing mat defects.
      Citation: Transportation Research Record
      PubDate: 2021-07-15T09:12:54Z
      DOI: 10.1177/03611981211020003
       
  • Hierarchical Scheme for Vehicle Make and Model Recognition

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      Authors: Chaoqing Wang, Junlong Cheng, Yuefei Wang, Yurong Qian
      Abstract: Transportation Research Record, Ahead of Print.
      A vehicle make and model recognition (VMMR) system is a common requirement in the field of intelligent transportation systems (ITS). However, it is a challenging task because of the subtle differences between vehicle categories. In this paper, we propose a hierarchical scheme for VMMR. Specifically, the scheme consists of (1) a feature extraction framework called weighted mask hierarchical bilinear pooling (WMHBP) based on hierarchical bilinear pooling (HBP) which weakens the influence of invalid background regions by generating a weighted mask while extracting features from discriminative regions to form a more robust feature descriptor; (2) a hierarchical loss function that can learn the appearance differences between vehicle brands, and enhance vehicle recognition accuracy; (3) collection of vehicle images from the Internet and classification of images with hierarchical labels to augment data for solving the problem of insufficient data and low picture resolution and improving the model’s generalization ability and robustness. We evaluate the proposed framework for accuracy and real-time performance and the experiment results indicate a recognition accuracy of 95.1% and an FPS (frames per second) of 107 for the framework for the Stanford Cars public dataset, which demonstrates the superiority of the method and its availability for ITS.
      Citation: Transportation Research Record
      PubDate: 2021-07-15T09:08:13Z
      DOI: 10.1177/03611981211019743
       
  • Investigating Underage Alcohol-Intoxicated Driver Crash Patterns in
           Louisiana

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      Authors: Md Mahmud Hossain, M. Ashifur Rahman, Xiaoduan Sun, Elisabeta Mitran
      Abstract: Transportation Research Record, Ahead of Print.
      Despite the zero tolerance and minimum legal drinking age laws since 1999, crashes caused by underage drinking drivers have occurred every year in the United States, which is a huge cause for concern for roadway safety. This study utilized multiple correspondence analysis (MCA) on 9 years (2010 to 2018) of at-fault, underage (aged 15 to 20 years), alcohol-intoxicated driver crashes in Louisiana to investigate hidden crash attribute patterns. This exploratory multivariate analysis technique identifies systematic associations among categories of qualitative variables rather than recognizing the effect of a single factor on the response variable. The results exhibited the capability of MCA in discovering the meaningful clouds of crash contributory factors from a complex multidimensional dataset. Fatal crashes happened to underage alcohol-intoxicated drivers who were not using seatbelts on high-speed curve segments under dark without streetlights, whereas single-vehicle crashes resulted in moderate injuries among drinking novice teenagers operating light trucks. The findings also revealed the driving behavior patterns of rookie drivers after alcohol intake that resulted in collisions. For example, male teenagers were engaged in impaired driving during weekends under adverse weather conditions, and underage drinking drivers tended to use cellphones during late-night driving. Targeting critical attributes identified from associations could be helpful in reducing the number of related crashes and fatalities. Furthermore, knowledge gained about the attribute groups identified in this study could be included in educational training programs targeting risky driving maneuvers. Integration of multiple interventions could be more strategic in minimizing underage drinking collisions.
      Citation: Transportation Research Record
      PubDate: 2021-07-15T09:05:33Z
      DOI: 10.1177/03611981211019742
       
  • Characterizing the Particle Variations and Human Exposure in Port and
           Urban Areas

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      Authors: Hong-Mei Zhao, Hong-Di He, Ji-Qiang Zhao, Yi Ding, Zhong-Ren Peng, Hong-Wei Wang
      Abstract: Transportation Research Record, Ahead of Print.
      In port areas, traffic is characterized by container trucks which run on diesel, while in urban areas it is characterized by private cars which run on petrol. The different fuels as pollution sources cause distinct particle pollution. This study offers an in-depth investigation of particle pollution and corresponding short-term exposures in port and urban areas. Field measurements were carried out to collect the data including particulate matter and traffic volume. Based on the data, firstly, the Pearson correlation analysis was performed to analyze the relationships between traffic volume and particles. Secondly, the Anderson–Darling test was adopted to identify the “best-fit” distributions on particles. Thirdly, comparisons of particle pollution levels in port and urban areas were analyzed. Finally, the pedestrian respiratory deposition doses of particles were estimated. The results indicate the importance and urgency of reducing air pollution, especially for port cities, and provide policymakers with a foundation for possible measures in the port city.
      Citation: Transportation Research Record
      PubDate: 2021-07-15T09:03:52Z
      DOI: 10.1177/03611981211019041
       
  • Influence of Lining Design Parameters on the Greenhouse Gas Emissions of
           Chinese Highway Tunnel Construction

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      Authors: Jianfeng Xu, Chen Dong, Dongming Guo, Chun Guo
      Abstract: Transportation Research Record, Ahead of Print.
      To realize low-carbon design for tunnel construction, the authors explored the relationship between tunnel design and greenhouse gas (GHG) emissions. This study proposed typical design models of Chinese highway tunnels based on the lining design specifications and engineering design cases. The research modified the GHG emission calculation method based on the standard quota system. The marginal GHG emissions caused by a change of design parameters of tunnel lining were determined. The results show that the emissions from shotcrete, concrete arch wall, system bolts, and steel frames are sensitive to the change of design parameters, while steel mesh is not. As the design thickness increases, the emissions of the concrete arch wall, inverted arch, and shotcrete increase approximately linearly. The emission distributions of system bolts and steel frames under different spacing are given. Under the same longitudinal spacing condition, the emission ratio of I18 and I16 steel frames is 1.197, and that of I16 and I14 steel frames is 1.316. By defining the marginal emissions caused by the change of design parameters, this study carried out basic work for highway tunnel low-carbon designs. The research is of strategic significance for achieving energy conservation and emission reduction in the tunnel industry.
      Citation: Transportation Research Record
      PubDate: 2021-07-15T09:01:52Z
      DOI: 10.1177/03611981211019039
       
  • Joint Modeling of Access Mode and Parking Choice of Air Travelers Using
           Revealed Preference Data

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      Authors: Yanbo Ge, Alec Biehl, Srinath Ravulaparthy, Venu Garikapati, Monte Lunacek, Caleb Phillips
      Abstract: Transportation Research Record, Ahead of Print.
      Airport ground access mode choice is distinct from everyday mode choice decisions, necessitating context-specific choice model estimation. Understanding airport ground access mode choice decisions is not only important for developing infrastructure planning strategies, but also for assessing the impacts of emerging modes on airport revenues, particularly from parking. However, parking choice is an often-overlooked dimension in airport ground access choice modeling. This paper addresses this gap through the development of a joint model of airport access mode and parking option choice using a passenger survey conducted at Dallas-Fort Worth (DFW) International Airport in 2015. Compared with a traditional conditional logit model that does not consider parking options available at DFW airport, the joint model of mode and parking decisions was found to generate more realistic values of travel time and was shown to have better predictive performance, both of which are critical for obtaining better airport parking revenue estimates and identifying traveler cohorts who may respond more strongly to potential policies targeting curb congestion and parking demand.
      Citation: Transportation Research Record
      PubDate: 2021-07-15T08:59:32Z
      DOI: 10.1177/03611981211019037
       
  • Joint Model of Sustainable Mode Choice for Commute, Shift Potential and
           Alternative Mode Chosen

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      Authors: Ganesh Ambi Ramakrishnan, Karthik K. Srinivasan, Aupal Mondal, Chandra R. Bhat
      Abstract: Transportation Research Record, Ahead of Print.
      Rising traffic congestion and severe air pollution in urban areas have led policymakers to find appropriate strategies to encourage the use of sustainable modes. In this context, this paper investigates three choice dimensions related to the work commute travel: (i) Whether and to what extent are sustainable modes considered' (ii) What factors influence the propensity to shift from the primary work commute mode' (iii) Which mode is most likely to be chosen conditional on the decision to shift' These dimensions are analyzed using data of workers from Chennai, India. As the three choices of an individual may be correlated and mutually endogenous because of common and persistent psychological attributes and modal service characteristics, they are modeled using a multi-dimensional probit model. The results show significant evidence of endogeneity, state-dependence, and unobserved correlation across these dimensions leading to significant improvement in fit measures. The results show that perceptions of walkability and environmental impacts of travel modes affect only the consideration of sustainable modes, while vehicle ownership and accessibility to transit affect all three dimensions. Four different behavioral motivations for the decision to shift from the usual mode: dissatisfaction with service attributes, activity constraints, multimodal travel pattern, and inertia, were identified. The mode to which shift occurs is influenced by household vehicle fleet (number and type), exclusive availability to the given decision-maker, and work distance. The insights from this study can be used to identify suitable factors and frame policies to promote sustainable mode choice at various levels.
      Citation: Transportation Research Record
      PubDate: 2021-07-15T08:57:29Z
      DOI: 10.1177/03611981211017908
       
  • Five-Year Project-Level Statewide Pavement Performance Forecasting Using a
           Two-Stage Machine Learning Approach Based on Long Short-Term Memory

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      Authors: Alexander W. Bukharin, Zhongyu Yang, Yichang (James) Tsai
      Abstract: Transportation Research Record, Ahead of Print.
      An accurate pavement performance forecasting model is essential for transportation agencies to perform pavement maintenance, rehabilitation, and reconstruction (MR&R) in a predictive and cost-effective manner. Although some forecasting methods have been successful in forecasting short-term (e.g., 1–2 year) pavement conditions at either the project level or network level, accurately forecasting long-term (e.g., 3–5 year) pavement conditions at both project level and network level under real-world conditions is still challenging. Thus, the goal of this paper is to propose a two-stage machine learning approach based on long short-term memory (LSTM) to achieve not only the short-term, but also the long-term, forecasting accuracy at both the project level and network level. The proposed method involves LSTM in the first stage and an artificial neural network (ANN) in the second stage, resulting into a two-stage model. The LSTM first learns the pattern of pavement deterioration based on sequential data (e.g., historical pavement conditions). Then, the ANN further learns the impacts of roadway factors (e.g., traffic parameter, pavement surface type, working district) to adjust the final forecasting results. The accuracy of the proposed two-stage model has been compared with baseline machine learning methods in 2016 on a large, statewide Florida dataset at both the project level and network level to demonstrate the superior capability of the proposed method. In addition, the proposed method has been tested further to forecast future (5-year) pavement conditions (2016–2020). Results show a promising forecasting accuracy for both the short-term and long-term in comparison with the ground truth.
      Citation: Transportation Research Record
      PubDate: 2021-07-15T08:55:09Z
      DOI: 10.1177/03611981211017132
       
  • Equity-Advancing Practices at Public Transit Agencies in the United States

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      Authors: Alex Karner, Kaylyn Levine
      Abstract: Transportation Research Record, Ahead of Print.
      Consistent with federal anti-discrimination and environmental justice law and guidance, public transportation agencies must evaluate the extent to which their decisions benefit and burden different people and groups and they must also conduct public engagement during decision-making. Assessing benefits and burdens and facilitating engagement are critically important for achieving transportation equity. In practice, quantitative analyses of plan impacts can be used to highlight and mitigate disparate benefits and burdens, but analyses are often conducted after major decisions have already been made and agencies have substantial flexibility in data collection and analysis. Public engagement can also affect equity-related outcomes, but agencies still rely heavily on public meetings and one-way information dissemination approaches that alienate potential participants. Considering the shortcomings associated with quantitative analysis and traditional public engagement as well as the open-ended nature of existing regulatory guidance, there is a need to understand the broad range of approaches that public transit agencies use to pursue equity-related goals. In this review of practice, we summarize six measures that agencies are using to advance transportation equity. Each measure is described using information gleaned from semi-structured interviews and primary source materials. We also identify challenges and shortcomings inherent in each approach using perspectives from the academic literature. The results will be useful for practitioners seeking equitable public transit systems and desiring to go beyond the standard approaches suggested by federal law and guidance.
      Citation: Transportation Research Record
      PubDate: 2021-07-15T01:25:26Z
      DOI: 10.1177/03611981211016861
       
  • Will We Fly Again' Modeling Air Travel Demand in light of COVID-19
           through a London Case Study

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      Authors: Francesco Manca, Aruna Sivakumar, Jacek Pawlak, Norbert J Brodzinski
      Abstract: Transportation Research Record, Ahead of Print.
      The COVID-19 pandemic and associated travel restrictions have created an unprecedented challenge for the air transport industry, which before the pandemic was facing almost the exact opposite set of problems. Instead of the growing demand and need for capacity expansion warring against environmental concerns, the sector is now facing a slump in demand and the continuing uncertainty about the impacts of the pandemic on people’s willingness to fly. To shed light on consumer attitudes toward air travel during and post the pandemic, this study presents an analysis that draws on recently collected survey data (April–July 2020), including both revealed and stated preference components, of 388 respondents who traveled from one of the six London, U.K., airports in 2019. Several travel scenarios considering the circumstances and attitudes related to COVID-19 are explored. The data is analyzed using a hybrid choice model to integrate latent constructs related to attitudinal characteristics. The analysis confirms the impact of consumers’ health concerns on their willingness to travel, as a function of travel characteristics, that is, cost and number of transfers. It also provides insights into preference heterogeneity as a function of sociodemographic characteristics. However, no significant effects are observed concerning perceptions of safety arising from wearing a mask, or concerns over the necessity to quarantine. Results also suggest that some respondents may perceive virtual substitutes for business travel, for example video calls and similar software, as only a temporary measure, and seek to return to traveling as soon as it is possible to do so safely.
      Citation: Transportation Research Record
      PubDate: 2021-07-14T09:55:09Z
      DOI: 10.1177/03611981211025287
       
  • Travel Mode Choices in a Greening Market: The Impact of Electric Vehicles
           and Prior Investments

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      Authors: Jeremy van Dijk, Mehdi Farsi, Sylvain Weber
      Abstract: Transportation Research Record, Ahead of Print.
      Through a choice experiment conducted among 995 Swiss respondents, we studied the linkages between prior investment decisions and the choice of travel mode. Our experimental design and empirical framework aimed to identify the impact of electric vehicles (EVs) and to test for two behavioral deviations from rationally optimal usage. Prior investment in a car or public transport pass could be used ex ante as a commitment device for overcoming self-control issues, or could affect mode choices ex post through the regret effect of sunk costs. We found no evidence to support the sunk cost hypothesis, but our findings provided partial evidence in favor of commitment mechanisms. A prior investment decision decreased the consumer’s responsiveness to variation of travel time. However, such commitments did not seem to influence responses to changes in marginal travel costs. Further, we found that EV adoption in the experiment did not result in a significant step-change in hypothetical usage patterns above rational marginal cost reactions. Our results thus reinforced the importance of financial incentives in policies aimed at a behavioral change in travel mode choices.
      Citation: Transportation Research Record
      PubDate: 2021-07-14T09:54:03Z
      DOI: 10.1177/03611981211025279
       
  • Deep Learning for the Detection and Recognition of Rail Defects in
           Ultrasound B-Scan Images

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      Authors: Zhengxing Chen, Qihang Wang, Kanghua Yang, Tianle Yu, Jidong Yao, Yong Liu, Ping Wang, Qing He
      Abstract: Transportation Research Record, Ahead of Print.
      Rail defect detection is crucial to rail operations safety. Addressing the problem of high false alarm rates and missed detection rates in rail defect detection, this paper proposes a deep learning method using B-scan image recognition of rail defects with an improved YOLO (you only look once) V3 algorithm. Specifically, the developed model can automatically position a box in B-scan images and recognize EFBWs (electric flash butt welds), normal bolt holes, BHBs (bolt hole breaks), and SSCs (shells, spalling, or corrugation). First, the network structure of the YOLO V3 model is modified to enlarge the receptive field of the model, thus improving the detection accuracy of the model for small-scale objects. Second, B-scan image data are analyzed and standardized. Third, the initial training parameters of the improved YOLO V3 model are adjusted. Finally, the experiments are performed on 453 B-scan images as the test data set. Results show that the B-scan image recognition model based on the improved YOLO V3 algorithm reached high performance in its precision. Additionally, the detection accuracy and efficiency are improved compared with the original model and the final mean average precision can reach 87.41%.
      Citation: Transportation Research Record
      PubDate: 2021-07-14T09:53:04Z
      DOI: 10.1177/03611981211021547
       
  • Multicity Investigation of the Effect of Holidays on Bikeshare System
           Ridership

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      Authors: Lori Palaio, Tung Vo, Michael Maness, Robert L. Bertini, Nikhil Menon
      Abstract: Transportation Research Record, Ahead of Print.
      Bikeshare provides important first mile–last mile, commuting, circulation, and sightseeing options in many cities. Bikeshare can also be healthy and convenient for users. Throughout the year, holidays occur that change typical bikeshare activity patterns. Existing literature shows mixed results relating to the ridership impacts of holidays: some research shows that these days may result in higher ridership, whereas others show no effect. Because of variations in system locations and modeling methods, it is difficult to determine the reasons for these mixed results. To control for these aspects, this project consisted of a multicity study of the effect of holidays on system-level ridership using a loglinear regression model with robust standard errors. The results showed the impacts of holidays on bikeshare system ridership for different user types among systems in the Washington D.C., Chicago, Boston, Los Angeles, and Minneapolis metro areas. Several hypotheses were developed and tested to examine the effects of holidays on bikeshare usage. A major finding from this study was that federal holidays negatively affected member ridership and positively affected nonmember ridership. It was also found that different federal holidays had dissimilar effects on total ridership. These findings could be useful for bikeshare agencies to plan, reposition fleet, and improve system operation.
      Citation: Transportation Research Record
      PubDate: 2021-07-14T09:50:03Z
      DOI: 10.1177/03611981211019739
       
  • Sustainable Safety in The Netherlands Creating a Road Environment where
           People on Foot and on Bikes are as Safe as People in Cars

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      Authors: Ge Shi, Vannesa Methoxha, Carol Atkinson-Palombo, Norman Garrick
      Abstract: Transportation Research Record, Ahead of Print.
      Road crashes claim over one million lives each year worldwide, overwhelmingly in low- and middle-income countries. A handful of higher-income countries have made great progress in reducing traffic fatalities and are moving toward Vision Zero. The goal of this study is to evaluate how one such country, the Netherlands, has cut its traffic fatalities by over 90%. The results show that the Dutch have virtually eliminated the concept of “vulnerable road users” in that the risk of fatality for pedestrians, bicyclists and vehicle occupants has all converged at a low level. This is an amazing achievement, especially when compared with countries like the U.S. where the risk of fatality for non-vehicle occupants is 5–8 times that of vehicle occupants. In this paper, we assess the evolution of risk for different types of road users in the Netherlands since 1970. We also review critical events, advocacy, policies, and programs that were implemented in the Netherlands over the last five decades to address the issue of traffic safety. This analysis demonstrates that the Dutch used protests and advocacy campaigns to garner support for policies and programs that promoted non-motorized transportation as routine mobility choice. Furthermore, the governing body for safety in the Netherlands was an early adopter (in the 1990s) of a systems-based approach to traffic safety called Sustainable Safety. A 2020 FHWA webinar highlights that this systems-based approach is now beginning to take hold in the U.S.
      Citation: Transportation Research Record
      PubDate: 2021-07-14T09:45:23Z
      DOI: 10.1177/03611981211019736
       
  • Automatic Rail Surface Defects Inspection Based on Mask R-CNN

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      Authors: Feng Guo, Yu Qian, Dimitris Rizos, Zhi Suo, Xiaobin Chen
      Abstract: Transportation Research Record, Ahead of Print.
      Rail surface defects have negative impacts on riding comfort and track safety, and could even lead to accidents. Based on the safety database (2020) of the Federal Railroad Administration (FRA), rail surface defects have been among the main factors causing derailments. During the past decades, there have been many efforts to detect such rail surface defects. However, the applications of earlier methods are limited by the high requirements of specialized equipment and personnel training. To date, rail surface defect inspection is still a very labor-intensive and time-consuming process, which hardly satisfies the field maintenance expectations. Therefore, a cost-effective and user-friendly automatic system that can inspect the rail surface defects with high accuracy is urgently needed. To address this issue, this study proposes a computer vision-based instance segmentation framework for rail surface defect inspection. A rail surface database including 1,040 images (260 source images and 780 augmented images) has been built. The classic instance segmentation model, Mask R-CNN, has been re-trained and fine-tuned for inspecting rail surface defects with the customized dataset. The influences of different backbones and learning rates are investigated and discussed. Experimental results indicate the ResNet101 backbone reaches better inspection capability. With a learning rate of 0.005, the re-trained Mask R-CNN model can achieve the best performance on the bounding box and mask predictions. Sixteen images are used to test the inspection performance of the fine-tuned model. The results are promising and indicate potential field applications in the future.
      Citation: Transportation Research Record
      PubDate: 2021-07-14T09:41:43Z
      DOI: 10.1177/03611981211019034
       
  • Surrounding Vehicles’ Contribution to Car-Following Models:
           Deep-Learning-Based Analysis

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      Authors: Saeed Vasebi, Yeganeh M. Hayeri, Peter J. Jin
      Abstract: Transportation Research Record, Ahead of Print.
      Relatively recent increased computational power and extensive traffic data availability have provided a unique opportunity to re-investigate drivers’ car-following (CF) behavior. Classic CF models assume drivers’ behavior is only influenced by their preceding vehicle. Recent studies have indicated that considering surrounding vehicles’ information (e.g., multiple preceding vehicles) could affect CF models’ performance. An in-depth investigation of surrounding vehicles’ contribution to CF modeling performance has not been reported in the literature. This study uses a deep-learning model with long short-term memory (LSTM) to investigate to what extent considering surrounding vehicles could improve CF models’ performance. This investigation helps to select the right inputs for traffic flow modeling. Five CF models are compared in this study (i.e., classic, multi-anticipative, adjacent-lanes, following-vehicle, and all-surrounding-vehicles CF models). Performance of the CF models is compared in relation to accuracy, stability, and smoothness of traffic flow. The CF models are trained, validated, and tested by a large publicly available dataset. The average mean square errors (MSEs) for the classic, multi-anticipative, adjacent-lanes, following-vehicle, and all-surrounding-vehicles CF models are 1.58 × 10−3, 1.54 × 10−3, 1.56 × 10−3, 1.61 × 10−3, and 1.73 × 10−3, respectively. However, the results show insignificant performance differences between the classic CF model and multi-anticipative model or adjacent-lanes model in relation to accuracy, stability, or smoothness. The following-vehicle CF model shows similar performance to the multi-anticipative model. The all-surrounding-vehicles CF model has underperformed all the other models.
      Citation: Transportation Research Record
      PubDate: 2021-07-14T09:40:03Z
      DOI: 10.1177/03611981211018693
       
  • Evaluation of Traffic Signal Systems Effectiveness in Connected Vehicle
           Environments Using Trajectory Analytics

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      Authors: Marija Ostojic, Hani S. Mahmassani
      Abstract: Transportation Research Record, Ahead of Print.
      One of the ways to design more effective signal control strategies is to leverage and synthesize connected vehicle generated (CVG) information to identify traffic states for the controller to operate in a predictive, yet vehicle-actuated manner. The contribution of this paper is twofold: (1) it presents a framework for an advanced, online, signal control logic in a connected environment that utilizes information from connected vehicles (CVs) to augment high-resolution controller and/or sensor data, and (2) it applies the trajectory analytics to compare the performance of the new controller schemes with CVG data and functionalities relative to conventional, vehicle-actuated, control. The framework puts forward a predictive control logic that schedules phases in an acyclic manner over a variable planning horizon. Phase duration is continually evaluated in response to updated requests for service distributed among equipped vehicles and associated performance indicators. Within the same connected control setup, two measures of effectiveness of a decision were compared to determine the upper bound on the potential effectiveness of a more responsive control strategy. Finally, trajectory analytics was used to evaluate the effectiveness of the CV technology-based control scheme against the conventional one. The findings indicate that both control system performance assessment and optimization objectives should change with access to CVG data. Unlike current state of the practice controllers, the developed method is able to handle high and low demand states equally well. The designed connected controller is shown to be robust in handling varying traffic conditions and demand levels.
      Citation: Transportation Research Record
      PubDate: 2021-07-14T09:38:23Z
      DOI: 10.1177/03611981211018470
       
  • Simulation Analyses of End-Around Taxiway Operations under Four Different
           Runway and Taxiway Choices

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      Authors: Yilin Feng, Mary E. Johnson
      Abstract: Transportation Research Record, Ahead of Print.
      End-around taxiways (EAT) have been implemented at four major U.S. airports to increase the safety and throughput of parallel runway systems. This paper proposes two new runway and taxiway choices that become possible because of EATs. Instead of using the inboard runway to take off, the departing aircraft could use the outboard runway and use the EAT as the taxi-out path. A discrete-event stochastic simulation model simulates the operations of four different runway and taxiway choices. Two experiments compare the performance of the four choices on average taxi times, average fuel consumption per taxi, and number of runway crossings. In general, the results indicate that using the outboard runway to take off and the EAT as a taxi-out path would yield benefits in both taxi-in and taxi-out performance, as well as enhancing runway safety. Using the outboard runway to land and the EAT as a taxi-in path would yield benefit in taxi-out performance and runway safety at the expense of a longer taxi-in time. Concerns related to using the EAT as the taxi-out path, as well as potential future research topics, are discussed.
      Citation: Transportation Research Record
      PubDate: 2021-07-14T09:37:08Z
      DOI: 10.1177/03611981211018466
       
  • Investigating Degree of Blending Between Reclaimed Asphalt Pavement and
           Virgin Binder Using Atomic Force Microscopy and Focused Ion Beam

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      Authors: Mansour Solaimanian, Xuan Chen
      Abstract: Transportation Research Record, Ahead of Print.
      Adding reclaimed asphalt pavement (RAP) into asphalt mixes is a common practice and has many merits such as reducing costs and emissions. In recent decades, many state highway agencies have embarked on investigating asphalt mixes with high RAP content. As the RAP content increases, understanding how well the RAP binder blends with virgin binder becomes more crucial. Lack of knowledge on how much of the residual RAP binder actively blends with virgin binder during production is one of the reasons preventing full exploitation of RAP materials. Obviously, the amount of aged RAP binder blending into virgin binder affects the properties of asphalt mixes. A study was undertaken to investigate the degree of blending, that is, the amount of RAP binder blended with virgin binder, through atomic force microscopy (AFM) and focused ion beam (FIB). The AFM measurements were conducted on both binder samples and RAP aggregate samples; the former consisted of extracted and recovered RAP binder, virgin binder, and blended binder, while the latter covered blended RAP aggregate and virgin binder samples. AFM measurements on binders indicated that blended RAP and virgin binder, at the blending zone between RAP and virgin binder, has moduli between that of pure RAP binder and pure virgin binder. AFM was also explored to investigate the degree of blending using RAP aggregate and virgin binder, but preparation of acceptable samples for such work was not possible, in spite of extensive work in preparation of such samples through mechanical polishing and FIB.
      Citation: Transportation Research Record
      PubDate: 2021-07-14T09:33:03Z
      DOI: 10.1177/03611981211018465
       
  • Application of Advanced Driver-Assistance Systems in Police Vehicles

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      Authors: Vanessa Nasr, David Wozniak, Farzaneh Shahini, Maryam Zahabi
      Abstract: Transportation Research Record, Ahead of Print.
      Motor vehicle crashes are one of the leading causes of injuries and deaths for police officers. Advanced driver-assistance systems (ADAS) are driving control systems that have been found to improve civilian drivers’ safety; however, the impact of ADAS on police officers’ driving safety has yet to be investigated thoroughly. Disparities between driver states and tasks performed while driving between police and civilian drivers necessitate this distinction. This study identified the types of ADAS used in police vehicles, their impact on officers’ safety, and proposed potential future ADAS features to be implemented in police vehicles. A systematic literature review was conducted using Google Scholar, Compendex, Web of Science, Transport Research International Documentation (TRID), and Google Patents databases to identify the most prevalent police vehicles used in the U.S., available ADAS features in those vehicles, and the impact of ADAS on officers’ safety. A list of recommended ADAS features was developed based on the review of literature, authors’ knowledge and experience in the field, and the findings of an online survey with 73 police officers. Results indicated the addition of multiple ADAS features including the front vehicle detection system, intersection collision avoidance, evasive steering systems, left turn assist, traffic sign detection system, traffic jam assist, two lane and lane-ending detection, wrong-way alert, and autonomous highway driving features have the potential to improve officer safety and performance while driving. However, there was a void of studies focused on ADAS effects on police driving safety which needs to be addressed in future investigations.
      Citation: Transportation Research Record
      PubDate: 2021-07-14T09:32:03Z
      DOI: 10.1177/03611981211017144
       
  • Ruggedness Evaluation and Precision Estimates for Newly Developed Test
           Methods for Asphalt-Treated Cold Recycled Pavements

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      Authors: Adam J. T. Hand, Ilker Boz, Murugaiyah Piratheepan, Forrest Hierholzer, Brian K. Diefenderfer, David Jones, Jhony Habbouche, Stefan Louw
      Abstract: Transportation Research Record, Ahead of Print.
      Asphalt-treated cold recycled pavements, including cold in place recycling, full depth reclamation, and cold central plant recycling, are becoming popular rehabilitation options because they are economical, sustainable, and provide good performance. Because asphalt-treated cold recycled pavements use foamed or emulsified binder, they require a curing period post-construction before being opened to traffic or surfaced. Uniform guidelines on when an asphalt-treated cold recycled roadway can be opened to traffic or surfaced are not widely established, many are based on time or moisture content, and extreme ranges exist among agency specifications. Mixture designs also vary widely among agencies with regard to active filler use and asphalt recycling agents, further complicating the determination of necessary curing time. NCHRP Project 09-62 investigated a variety of test methods for determining when a recycled roadway could be opened to traffic or surfaced. This included extensive laboratory and field evaluations. New shear strength and raveling test methods were developed. For each test method a ruggedness study and inter-laboratory study were performed. The ruggedness study revealed critical test fixture and operation parameters. Six asphalt-treated cold recycled pavement process/material combinations were tested by three entities to develop precision estimates and statements (i.e., repeatability and reproducibility) for the new test methods. Tools and information from this study provide a rational basis for establishing specifications, which will help reduce pavement damage from early traffic and minimize roadway closures and delays.
      Citation: Transportation Research Record
      PubDate: 2021-07-14T09:30:23Z
      DOI: 10.1177/03611981211017142
       
  • Different Safety Awareness and Route Choice between Frequent and
           Infrequent Bicyclists: Findings from Revealed Preference Study Using
           Bikeshare Data

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      Authors: Nitesh R. Shah, Christopher R. Cherry
      Abstract: Transportation Research Record, Ahead of Print.
      Understanding the factors influencing bicycling is important to improve educational and built-environment investments to increase bicycling rates. Although factors such as the physical environment, sociodemographics, and psychology influence bicycling, safety is also one of the primary reasons people avoid bicycling. Interventions based on objective safety can reduce the number of crashes, injuries, and fatalities, but people might still feel uncomfortable bicycling owing to subjective safety (perceived safety or avoidance of risk). Several studies have examined the subjective safety of bicyclists based on stated-preference surveys, but these studies have limitations, including response bias. A revealed preference method was implemented by combining 9,101 bicycling trips of Grid Bike Share in Arizona with transportation network and crash data. A segmented path size correction logit model identified that regular bicyclists took a 1.6-times longer detour to avoid historic crash locations than casual bicyclists. These two groups also exhibited different choices related to the built environment and navigation. The significance of different types of bicyclists avoiding historic crash locations or risky infrastructure is that this indicates that crash datasets coupled with route data could be used as one of several indicators of perceived safety. Recommendations to increase perceived safety and reduce the crash risk of occasional bicyclists include expanding bicycle-specific infrastructure, constructing contraflow bicycle lanes in a one-way street, separating high volume lanes with a bike lane, and improving the education of road users.
      Citation: Transportation Research Record
      PubDate: 2021-07-14T09:27:31Z
      DOI: 10.1177/03611981211017136
       
  • Laboratory Evaluation of Aggregate Friction and Texture Properties

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      Authors: Emmanuel G. Fernando, Edith Arambula, Sheng Hu, William Crockford
      Abstract: Transportation Research Record, Ahead of Print.
      Aggregate shape, texture, and angularity are important physical properties for the development of high-quality adhesive systems with asphalt binder, and a good quality aggregate skeleton in asphalt and concrete mixtures. These properties are commonly measured using systems that employ images of aggregate samples taken with a digital camera. In practice, macro-texture measurements are commonly conducted nondestructively at highway speed using high-frequency lasers. There is a need to investigate the application of these optical sensors for measuring aggregate texture in the laboratory. Researchers used a laser-based scanning system to test aggregates from five sources before and after Micro-Deval abrasion. The aggregate specimens were embedded in a ring-shaped polyester material and tested with the aggregate ring texturing system (ARTS) along with the dynamic friction tester (DFT) to characterize micro-texture and frictional properties. Researchers analyzed the laboratory test data to evaluate the relationship between DFT friction at 60 km/h (DFT60) and the micro mean profile depth obtained with the ARTS. This analysis showed that the igneous and gravel aggregates had better micro-texture and frictional characteristics compared with the dolomite and limestone aggregates. The results from this implementation project showed the potential for using the ARTS to improve the Texas Department of Transportation’s existing surface aggregate classification system. Further testing is needed to characterize aggregates from other sources and compile a more comprehensive and representative database with which to establish meaningful aggregate classification criteria that include surrogate statistics for expected field performance.
      Citation: Transportation Research Record
      PubDate: 2021-07-14T09:26:02Z
      DOI: 10.1177/03611981211016465
       
  • Performance of Two Thin Epoxy Overlays on New Concrete under Laboratory
           and Outdoor Exposure Conditions

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      Authors: Abul Fazal Mazumder, Upul Attanayake, Neal S. Berke
      Abstract: Transportation Research Record, Ahead of Print.
      Thin epoxy overlays are used for improving the condition and extending the service life of bridge decks. The tensile bond pull-off strength, evaluated as per ASTM C1583, is used as the performance indicator. A failure in the substrate with a tensile strength of 250 pounds per square inch (psi) or greater is considered acceptable. However, the performance of in-service bridge decks when evaluated shows inconsistent results. Such studies failed to record and correlate the parameters that influence overlay performance during testing to clarify the observed variations. Laboratory studies by several researchers have documented a distinct performance difference when the overlays are exposed to room temperatures in comparison with elevated temperatures. However, the most influential parameters, such as the variation of substrate moisture against temperature and epoxy softening under elevated temperatures, were not measured and correlated to the observed performance. This study was initiated to provide clarification of the observed performance differences by evaluating the impact of concrete age at the time of epoxy application, concrete mix ingredients, exposure conditions, concrete microstructure development, and substrate moisture and temperature on the performance of two epoxy overlays. Experimental results confirm that (i) the performance of epoxy overlays improves when the concrete mix contains slag and (ii) substrate moisture vapor pressure and epoxy softening under elevated temperature negatively affect the overlay performance.
      Citation: Transportation Research Record
      PubDate: 2021-07-14T09:22:19Z
      DOI: 10.1177/03611981211016464
       
  • Finite Element Modeling of a Mechanically Stabilized Earth Trial Wall

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      Authors: Andrew Lees, Michael Dobie
      Abstract: Transportation Research Record, Ahead of Print.
      Polymer geogrid reinforced soil retaining walls have become commonplace, with routine design generally carried out by limiting equilibrium methods. Finite element analysis (FEA) is becoming more widely used to assess the likely deformation behavior of these structures, although in many cases such analyses over-predict deformation compared with monitored structures. Back-analysis of unit tests and instrumented walls improves the techniques and models used in FEA to represent the soil fill, reinforcement and composite behavior caused by the stabilization effect of the geogrid apertures on the soil particles. This composite behavior is most representatively modeled as enhanced soil shear strength. The back-analysis of two test cases provides valuable insight into the benefits of this approach. In the first case, a unit cell was set up such that one side could yield thereby reaching the active earth pressure state. Using FEA a test without geogrid was modeled to help establish appropriate soil parameters. These parameters were then used to back-analyze a test with geogrid present. Simply using the tensile properties of the geogrid over-predicted the yield pressure but using an enhanced soil shear strength gave a satisfactory comparison with the measured result. In the second case a trial retaining wall was back-analyzed to investigate both deformation and failure, the failure induced by cutting the geogrid after construction using heated wires. The closest fit to the actual deformation and failure behavior was provided by using enhanced fill shear strength.
      Citation: Transportation Research Record
      PubDate: 2021-07-14T09:20:34Z
      DOI: 10.1177/03611981211016456
       
  • Driving While Impaired and Riding with an Impaired Driver among Recent
           Latinx Immigrants

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      Authors: Eduardo Romano, Mariana Sanchez, Eileen P. Taylor, Rosa Babino
      Abstract: Transportation Research Record, Ahead of Print.
      The overarching aim of this study is to assess driving while impaired by alcohol (DWI) and riding with an impaired driver (RWID) rates among young adult Latinx immigrants to Miami-Dade County, Florida, within a year of arrival in the U.S.A. More specifically, this study aims to: (i) describe the demographic and socioeconomic characteristics of Latinx immigrants to Miami-Dade County within a year of arrival; (ii) examine their alcohol use, DWI, and RWID; and (iii) identify factors influencing these behaviors. This study uses baseline data from an ongoing National Institutes of Health-funded longitudinal study examining drinking and driving trajectories among young adult recent Latinx immigrants to Miami-Dade County. During the baseline assessment, retrospective pre-immigration data and post-immigration data were obtained via personal interviews. Inclusion criteria included being a Latinx immigrant, 18–34 years old, who recently immigrated (within one year before baseline assessment) to the U.S.A. from a Latin American country with the intention of staying in the U.S.A. for at least three years beyond baseline. Respondent-driven sampling was applied. Results showed that since arriving in the U.S.A. approximately 6.3% of all participants had engaged in DWI at least once and 20% reported RWID. Although household income and being male were significant factors, the factor that influenced post-immigration DWI/RWID the most was pre-immigration DWI (odds ratio = 13.1) and pre-immigration RWID (odd ratio = 24.5). Interventions aimed to prevent recent immigrants from engaging in DWI and RWID should take cultural factors and pre-immigration behaviors into account.
      Citation: Transportation Research Record
      PubDate: 2021-07-13T07:26:45Z
      DOI: 10.1177/03611981211014894
       
  • Human Factors Assessment of Pavement Marking Retroreflectivity in
           Simulated Rain and Dry Conditions

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      Authors: Timothy P. Barrette, Adam M. Pike
      Abstract: Transportation Research Record, Ahead of Print.
      Pavement marking retroreflectivity standards are typically developed with dry conditions in mind, however, driving at night during rainfall is seemingly one of the most challenging and stressful situations for a driver. Furthermore, existing research indicates continuous wet retroreflectivity is relatively weakly correlated with dry retroreflectivity and deteriorates differently over time, leading to the obvious conclusion that dry retroreflectivity standards alone are not enough to ensure that pavement markings meet the needs of drivers across the breadth of roadway conditions that may occur. Consequently, developing standards for minimum continuous wet retroreflectivity for new installations and for maintenance purposes represents an important area for research. This study aims to develop new installation and maintenance values for continuous wet retroreflectivity based on a multifaceted, closed-course study of detectability of pavement markings in simulated rain and dry conditions. A series of 20 pavement marking samples was evaluated in relation to detection distance and subjective rating. The results of the study indicated that pavement markings need to be maintained at a continuous wet retroreflectivity value of 50 mcd/m2/lux based on a participant pool that skewed older in age, but that likely represents something close to the 85th-percentile driver. Additional salient findings included observed wet retroreflectivity loss in the existing literature of approximately 7% per month, as well as the maximum preview time in simulated rain conditions being substantially lower than in dry conditions.
      Citation: Transportation Research Record
      PubDate: 2021-07-13T07:26:03Z
      DOI: 10.1177/03611981211011172
       
  • Bilevel Optimization of Intercity Railway Alignment

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      Authors: Dongying Yang, Qing He, Sirong Yi
      Abstract: Transportation Research Record, Ahead of Print.
      Intercity railway transit is the primary way to transfer passengers and freight over long distances on land. The design of an intercity railway alignment is usually challenging and complex because of great topographic variations and intersections with many existing geographic objects. This paper presents a bilevel optimization model for intercity railway alignment (BRAO) following the horizontal-vertical alignment design philosophy. The upper level is the horizontal alignment optimization, while the nested lower level is the vertical alignment optimization. A multistage augmented differential evolution algorithm is adopted for the solution at both levels. BRAO could generate corridor alignment, initial alignment, and optimal alignment through different allocations of the number and boundaries of decision variables. A real-world case study of railway design is conducted to verify the effectiveness of the BRAO model based on a geographic information system.
      Citation: Transportation Research Record
      PubDate: 2021-07-12T10:22:18Z
      DOI: 10.1177/03611981211023756
       
  • Composition and Oxidation Dependence of Glass Transition in Epoxy Asphalt

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      Authors: Panos Apostolidis, Xueyan Liu, Sandra Erkens, Tom Scarpas
      Abstract: Transportation Research Record, Ahead of Print.
      Miscibility, and lack of it, is decisive for durable polymer-modified asphalt binders and reflects the long-term performance of asphalt materials in terms of fatigue and thermal cracking. In this work, the glass transition behavior of epoxy asphalt will be assessed extensively after different oxidative aging time periods using differential scanning calorimetry. The composition dependence of glass transition in epoxy asphalt binders over oxidative aging is evaluated by emphasizing the deviation of glass transition temperature (Tg) with the change in sign and magnitude. An entropy-based analysis of glass transitions in epoxy asphalt is discussed as well. The blends formulated by epoxy and asphalt binder have shown an increase of the Tg deviation from the ideal mixing rule over oxidative aging. Two different shapes of the composition dependence of the Tg values are observed between the blends with and without fillers but showing both distinct positive deviations from the case of mixing ideal materials. The Tg and heat capacity (Cp) parameters determined in relation to the epoxy asphalt composition provide insights into the effect of limestone fillers on the oxidation-induced embrittlement of epoxy asphalt materials. The results could help select the epoxy proportion in asphalt to develop super-durable and long-lasting pavement materials.
      Citation: Transportation Research Record
      PubDate: 2021-07-12T10:20:17Z
      DOI: 10.1177/03611981211024243
       
  • Modeling Car-Following Heterogeneities by Considering Leader–Follower
           Compositions and Driving Style Differences

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      Authors: Zhanbo Sun, Xue Yao, Ziye Qin, Peitong Zhang, Ze Yang
      Abstract: Transportation Research Record, Ahead of Print.
      To better understand the behavioral heterogeneities of human-operated vehicles, the paper proposes a method to distinguish car-following behaviors in specific leader–follower contexts. Using the Next-Generation Simulation dataset, the car-following data are first classified into four leader–follower compositions, namely, truck–car, car–car, car–truck, and truck–truck. Based on the classified data, we calibrate the parameters of a few well-known car-following models, including Full Velocity Difference model, Intelligent Driver Model, and Gazis–Herman–Rothery model. Principal component analysis and clustering analysis are then applied to the calibrated parameters to discover the behavioral patterns and to find the probabilistic distributions of the parameters for the classified car-following (CCF) models. Simulation results show that compared with the unified car-following models, the estimation errors of calibrated CCF models are reduced by 20.79% to 49.05%, which indicates that the proposed method provides a more accurate description of car-following heterogeneities. The proposed framework could help highway traffic operators better know the traffic users.
      Citation: Transportation Research Record
      PubDate: 2021-07-12T10:18:58Z
      DOI: 10.1177/03611981211020006
       
  • Spatial and Temporal Differences in Weekday Travel Durations Between
           Private-for-Hire Transportation Services and Transit in the City Center

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      Authors: Baxter Shandobil, Ty Lazarchik, Kelly Clifton
      Abstract: Transportation Research Record, Ahead of Print.
      There is increasing evidence that ridehailing and other private-for-hire (PfH) services such as taxis and limousines are diverting trips from transit services. One question that arises is where and when PfH services are filling gaps in transit services and where they are competing with transit services that are publicly subsidized. Using weekday trip-level information for trips originating in or destined for the city center of Portland, OR from PfH transportation services (taxis, transportation network companies, limousines) and transit trip data collected from OpenTripPlanner, this study investigated the temporal and spatial differences in travel durations between actual PfH trips and comparable transit trips (the same origin–destination and time of day). This paper contributes to this question and to a growing body of research about the use of ridehailing and other on-demand services. Specifically, it provides a spatial and temporal analysis of the demand for PfH transportation using an actual census of trips for a given 2 week period. The comparison of trip durations of actual PfH trips to hypothetical transit trips for the same origin–destination pairs into or out of the central city gives insights for policy making around pricing and other regulatory frameworks that could be implemented in time and space.
      Citation: Transportation Research Record
      PubDate: 2021-07-12T10:16:37Z
      DOI: 10.1177/03611981211019741
       
  • Incorporating Travel Time Reliability in Equitable Congestion Pricing
           Schemes for Heterogeneous Users and Bimodal Networks

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      Authors: Fatemeh Fakhrmoosavi, Ali Zockaie, Khaled Abdelghany
      Abstract: Transportation Research Record, Ahead of Print.
      Congestion pricing is proposed as an effective travel demand management strategy to circumvent the problem of congestion and generate revenue to finance developmental projects. There are several studies focusing on optimal pricing strategies to minimize the congestion level or maximize the revenue of the system. However, with regard to equity issues, benefiting only users with higher value of time is claimed to be the main factor that prevents implementation of such policies in practice. While many studies aimed to tackle the equity issues by certain welfare analyses, most of these studies fail to fully consider realistic features of users’ behavior and the uncertainty in link travel times. Given the variability of travel time in real-world networks and the impacts of pricing policies on path travel time distributions, it is important to consider the users’ reliability valuations, in addition to their travel time valuations. Thus, the goal in this study is to find an equitable pricing scheme that minimizes the total travel time of auto users in a general bimodal network considering heterogeneous users with different values of time and reliability. A particle swarm optimization algorithm is proposed to find self-funded and Pareto-improving optimal toll values. A reliability-based user equilibrium algorithm is embedded into this optimization algorithm to assign travelers to the equilibrated paths for different user classes given toll values. The proposed approach is successfully applied to a modified Sioux Falls network to explore impacts of subsidization, congestion level, and considering travel time reliability on the pricing strategy and its effectiveness.
      Citation: Transportation Research Record
      PubDate: 2021-07-12T10:14:37Z
      DOI: 10.1177/03611981211019737
       
  • Assessment of the Use of Polypropylene Fiber Reinforced Foam Concrete as a
           Subgrade Material for the China Railway Track System (CRTS) III Slab
           Ballastless Tracks

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      Authors: Thanut Klomranok, Qian Su
      Abstract: Transportation Research Record, Ahead of Print.
      This paper presents the application and the development of foam concrete (FC) to replace the traditionally used subgraded materials (typically compacted soil or granular earth rock) in high-speed railway by using cement to sand ratio of 2:1 with a target density of 500 to 700 kg/m3 and by adding polypropylene (PP) fibers with 0.25% and 0.40% by volume to improve the properties of FC. The mechanical properties were evaluated and tested in the laboratory in accordance with ASTM standard method, including compressive strength, tensile strength, modulus of elasticity and Poisson’s ratio, and dynamic strength. In addition, the numerical model investigates the performance and analyzes the effect of applying the full cross-section PP fiber reinforced FC in slab ballastless track, under different thicknesses, on the dynamic response of the whole structure, and then compares them with that of the traditional structure. The results indicate that the strength of FC with a density of 500 to 700 kg/m3 can meet the requirements of static and dynamic loading conditions of railway earth structure. But the density of 600 to 700 kg/m3 shows good strength stability under different curing states. In addition, adding 0.25% PP fiber is an optimal volume that can significantly improve mechanical properties. The prediction of the model shows that FC at a density of 600 kg/m3 by adding PP fibers of 0.25% at a thickness of 1.5 m can reduce the stress and vibration of the track structure better than that of the traditional structure; this indicates a long-term maintainance stability of the subgrade bed.
      Citation: Transportation Research Record
      PubDate: 2021-07-12T10:13:17Z
      DOI: 10.1177/03611981211019031
       
  • Hybrid-Data Approach for Estimating Trip Purposes

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      Authors: Xiaoling Luo, Adrian Cottam, Yao-Jan Wu, Yangsheng Jiang
      Abstract: Transportation Research Record, Ahead of Print.
      Trip purpose information plays a significant role in transportation systems. Existing trip purpose information is traditionally collected through human observation. This manual process requires many personnel and a large amount of resources. Because of this high cost, automated trip purpose estimation is more attractive from a data-driven perspective, as it could improve the efficiency of processes and save time. Therefore, a hybrid-data approach using taxi operations data and point-of-interest (POI) data to estimate trip purposes was developed in this research. POI data, an emerging data source, was incorporated because it provides a wealth of additional information for trip purpose estimation. POI data, an open dataset, has the added benefit of being readily accessible from online platforms. Several techniques were developed and compared to incorporate this POI data into the hybrid-data approach to achieve a high level of accuracy. To evaluate the performance of the approach, data from Chengdu, China, were used. The results show that the incorporation of POI information increases the average accuracy of trip purpose estimation by 28% compared with trip purpose estimation not using the POI data. These results indicate that the additional trip attributes provided by POI data can increase the accuracy of trip purpose estimation.
      Citation: Transportation Research Record
      PubDate: 2021-07-12T09:59:55Z
      DOI: 10.1177/03611981211018474
       
  • Freeway Network Travel Time Reliability Analysis Methodology and Software
           Tool Development

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      Authors: Wei Sun, Scott S. Washburn
      Abstract: Transportation Research Record, Ahead of Print.
      Applications in the field often require analysis of freeway travel time reliability (TTR) at the network level. While micro-simulation is suitable for performing network-level analysis, the computational burden can become unreasonable when TTR analysis is factored in. As for macro-simulation, most network analysis studies often use simplified link performance functions to represent the travel time and flow relationship. Such functions are not generally sensitive to the range of geometric and traffic conditions that can influence freeway facility operations. This research extends the Highway Capacity Manual (HCM) freeway TTR analysis methodology to the network level. The proposed freeway network TTR analysis methodology generates scenarios that represent the impacts of origin–destination (OD) demand variations, weather events, incident events, and work zone events on freeway network travel time. For each scenario, the methodology performs user equilibrium (UE) traffic assignment and the HCM freeway facility core methodology is applied to represent the travel time and flow relationship. The method of successive average approach is applied to solve the UE traffic assignment. Finally, scenario travel times (and/or other performance measures) are aggregated into various distributions of interest, such as the network-, facility-, and OD-level distributions, and TTR performance measures are calculated at the three different levels. A software tool is developed using C# language on the .NET Framework. The software tool provides a convenient and efficient approach for transportation planners and researchers to conduct the freeway network TTR analysis, which helps to bridge the gap between research and practice.
      Citation: Transportation Research Record
      PubDate: 2021-07-12T09:57:54Z
      DOI: 10.1177/03611981211018469
       
  • Estimation of Path Travel Time Distributions in Stochastic Time-Varying
           Networks with Correlations

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      Authors: Monika Filipovska, Hani S. Mahmassani, Archak Mittal
      Abstract: Transportation Research Record, Ahead of Print.
      Transportation research has increasingly focused on the modeling of travel time uncertainty in transportation networks. From a user’s perspective, the performance of the network is experienced at the level of a path, and, as such, knowledge of variability of travel times along paths contemplated by the user is necessary. This paper focuses on developing approaches for the estimation of path travel time distributions in stochastic time-varying networks so as to capture generalized correlations between link travel times. Specifically, the goal is to develop methods to estimate path travel time distributions for any path in the networks by synthesizing available trajectory data from various portions of the path, and this paper addresses that problem in a two-fold manner. Firstly, a Monte Carlo simulation (MCS)-based approach is presented for the convolution of time-varying random variables with general correlation structures and distribution shapes. Secondly, a combinatorial data-mining approach is developed, which aims to utilize sparse trajectory data for the estimation of path travel time distributions by implicitly capturing the complex correlation structure in the network travel times. Numerical results indicate that the MCS approach allowing for time-dependence and a time-varying correlation structure outperforms other approaches, and that its performance is robust with respect to different path travel time distributions. Additionally, using the path segmentations from the segment search approach with a MCS approach with time-dependence also produces accurate and robust estimates of the path travel time distributions with the added benefit of shorter computation times.
      Citation: Transportation Research Record
      PubDate: 2021-07-12T09:50:09Z
      DOI: 10.1177/03611981211018464
       
  • Extracting Rules from Autonomous-Vehicle-Involved Crashes by Applying
           Decision Tree and Association Rule Methods

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      Authors: Md Tanvir Ashraf, Kakan Dey, Sabyasachee Mishra, Md Tawhidur Rahman
      Abstract: Transportation Research Record, Ahead of Print.
      Autonomous vehicles (AVs) can dramatically reduce the number of traffic crashes and associated fatalities by eliminating the avoidable human-error-related crash contributing factors. Many companies have been conducting pilot tests on public roads in several states in the U.S. and other countries to accelerate AV mass deployment. AV pilot operations on Californian public roads saw 251 AV-involved crashes (as of February 2020). These AV-involved crashes provide a unique opportunity to investigate AV crash risks in the mixed traffic environment. This study collected the AV crash reports from the California Department of Motor Vehicles and applied the decision tree and association rule methods to extract the pre-crash rules of AV-involved crashes. Extracted rules revealed that the most frequent types of AV crashes were rear-end crashes and predominantly occurred at intersections when AVs were stopped and engaged in the autonomous mode. AV and non-AV manufacturers and transportation agencies can use the findings of this study to minimize AV-related crashes. AV companies could install a distinct signal/display to inform the operational mode of the AVs (i.e., autonomous or non-autonomous) to human drivers around them. Moreover, the automatic emergency braking system in non-AVs could avoid a significant number of rear-end crashes as, often, rear-end crashes occurred as a result of the failure of following non-AVs to slow down in time behind AVs. Transportation agencies can consider separating AVs from non-AVs by assigning “AV Only” lanes to eliminate the excessive rear-end crashes resulting from the mistakes of human drivers in non-AVs at intersections.
      Citation: Transportation Research Record
      PubDate: 2021-07-12T09:47:14Z
      DOI: 10.1177/03611981211018461
       
  • Input Parameters for the Mechanistic-Empirical Design of Full-Depth
           Reclamation Projects

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      Authors: Vishwa V. Beesam, Cristina Torres-Machi
      Abstract: Transportation Research Record, Ahead of Print.
      Cold recycling technologies such as full-depth reclamation (FDR) are sustainable and cost-effective techniques for pavement rehabilitation that reduce environmental impacts and construction costs and time. The limited information available on the material properties of FDR mixtures and their characterization in mechanistic-empirical (M-E) pavement design hinders the full deployment of FDR. Previous research has found current M-E default values to be non-representative and overly conservative, leading to an underestimation of the true performance capabilities of FDR materials. To address this gap, this paper analyzes the performance of 11 FDR sites constructed throughout Colorado, U.S., and compares their long-term performance with M-E predictions. The objective of this paper is to recommend input values for the M-E design of FDR base materials that result in reliable predictions of FDR long-term performance. The analysis includes both non-stabilized and emulsion-stabilized FDR projects. Both initial International Roughness Index (IRI) and resilient modulus were found to have a significant impact on M-E predictions and were calibrated in a two-step process. The proposed input parameters lead to a conservative design of FDR projects and result in improved IRI predictions compared with the ones derived from current design criteria. With the current design parameters, IRI predictions were, on average, overestimated by 51 in./mi, whereas the proposed input parameters make it possible to reduce this difference to 17 in./mi. Future research is needed to improve current models in M-E pavement design software to adequately model cold in-place recycled layers such as FDR.
      Citation: Transportation Research Record
      PubDate: 2021-07-12T09:45:47Z
      DOI: 10.1177/03611981211017916
       
  • Sequential Optimization of an Emergency Response Vehicle’s Intra-Link
           Movement in a Partially Connected Vehicle Environment

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      Authors: Gaby Joe Hannoun, Pamela Murray-Tuite, Kevin Heaslip, Thidapat Chantem
      Abstract: Transportation Research Record, Ahead of Print.
      This paper introduces a semi-automated system that facilitates emergency response vehicle (ERV) movement through a transportation link by providing instructions to downstream non-ERVs. The proposed system adapts to information from non-ERVs that are nearby and downstream of the ERV. As the ERV passes stopped non-ERVs, new non-ERVs are considered. The proposed system sequentially executes integer linear programs (ILPs) on transportation link segments with information transferred between optimizations to ensure ERV movement continuity. This paper extends a previously developed mathematical program that was limited to a single short segment. The new approach limits runtime overhead without sacrificing effectiveness and is more suitable to dynamic systems. It also accommodates partial market penetration of connected vehicles using a heuristic reservation approach, making the proposed system beneficial in the short-term future. The proposed system can also assign the ERV to a specific lateral position at the end of the link, a useful capability when next entering an intersection. Experiments were conducted to develop recommendations to reduce computation times without compromising efficiency. When compared with the current practice of moving to the nearest edge, the system reduces ERV travel time an average of 3.26 s per 0.1 mi and decreases vehicle interactions.
      Citation: Transportation Research Record
      PubDate: 2021-07-12T09:40:27Z
      DOI: 10.1177/03611981211017914
       
  • Predicting International Roughness Index Based on Surface Distresses in
           Various Climate and Traffic Conditions Using Laser Crack Measurement
           System

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      Authors: Mansour Fakhri, Seyed Masoud Karimi, Jalal Barzegaran
      Abstract: Transportation Research Record, Ahead of Print.
      Roughness is one of the most significant parameters in the evaluation of pavement performance. Surface distresses are among the main factors leading to roughness. The collection and evaluation of roughness data require the application of modern equipment such as road surface profilers. In the absence of such equipment, roughness prediction models that are based on surface distresses might provide a desirable assessment of pavement conditions. This research employs the laser crack measurement system (LCMS) to detect and measure surface distresses and roughness along 268 km of primary roads in Iran. Compared with manual survey, LCMS provides maximum detection and measurement accuracy. Based on the LCMS output, distresses with a higher correlation with the International Roughness Index (IRI) were selected as predictors in linear regression models and artificial neural networks (ANN). The models were developed for 10 m and 100 m length sections of the roads under different climate and traffic conditions. The results indicate that the performance of ANN for the 100 m sections with coefficient of determination (R2) of 0.82 is superior to other models. The best case was that of using ANN in 100 m sections for regions with moderate climate and medium traffic levels, with a 0.94 correlation. Satisfactory results in field validation of the models demonstrated that agencies can use other methods of data collection (e.g., manual, right of way [ROW]) to assess the surface distresses and roughness condition of their roads from the developed models with minimum spending and without expensive equipment. Such estimates can be employed to make informed decisions in pavement maintenance programs at the network level.
      Citation: Transportation Research Record
      PubDate: 2021-07-12T09:38:48Z
      DOI: 10.1177/03611981211017906
       
  • Statistical Distance-Based Travel-Time Reliability Measurement for Freeway
           Bottleneck Identification and Ranking

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      Authors: Zhuo Chen, Xiaoyue Cathy Liu
      Abstract: Transportation Research Record, Ahead of Print.
      Freeway bottleneck identification is an essential component in the process of deploying mitigation strategies to reduce congestion at freeway bottlenecks. Most previous studies on bottleneck identification focus on recurrent bottlenecks, and limited work has been conducted to identify the locations of non-recurrent bottlenecks. Therefore, in this study, we propose a new travel time reliability (TTR) measurement and develop a freeway bottleneck identification method based on this measurement, which can identify with high probability not only recurrent bottlenecks but also the locations of non-recurrent bottlenecks. The TTR measurement is developed based on statistical distance between travel time distributions. Three statistical distance measurements, Jensen–Shannon divergence, Wasserstein distance, and Hellinger distance, are applied in the TTR measurement. The bottleneck identification method is evaluated in a case study on I-15 freeway corridor in Salt Lake City, Utah. The three statistical distance measurements show good consistency in ranking locations by the impacts of recurrent and non-recurrent congestion, especially for extreme cases with very high or low variation between travel time distributions. The recurrent bottlenecks identified in this study show their clustering characteristics, which is similar to the generating and dismissing process of recurrent congestion. The locations with high probability of non-recurrent bottlenecks scatter both spatially and temporally, which agrees with the random characteristic of non-recurrent congestion.
      Citation: Transportation Research Record
      PubDate: 2021-07-12T09:37:07Z
      DOI: 10.1177/03611981211017905
       
  • Revealing Safety Risks of Unmanned Aerial Vehicles in Construction

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      Authors: Mostafa Namian, Mohammad Khalid, George Wang, Yelda Turkan
      Abstract: Transportation Research Record, Ahead of Print.
      Unmanned aerial vehicles (UAVs) have gained their prevalent recognition in construction because of their exceptional advantages. Despite the increasing use of UAVs in the industry and their remarkable benefits, there are serious potential safety risks associated that have been overlooked. Construction is one of the most hazardous industries in the United States. In addition to the ordinary hazards normally present in dynamic construction workplaces, UAVs can expose workers to a wider range of never-before-seen safety risks that must be recognized and controlled. The industry is not equipped with safety measures to prevent potential accidents, because of scarce research on drone-associated hazards and risks. The aim of this research was to (1) identify the UAV-associated hazards in construction that may expose personnel and property to potential harms, and (2) study the relative impact of each hazard and the associated safety risks. In Phase I, the researchers conducted an extensive literature review and consulted with a construction UAV expert. In Phase II, the researchers obtained data from 54 construction experts validating and evaluating the identified hazards and risks. The results revealed that adopting UAVs can expose construction projects to a variety of hazards that the industry is not familiar with. “Collision with properties,”“collision with humans,” and “distraction” were identified as the top three safety risks. Moreover, the study introduces effective strategies, such as having qualified crew members, proper drone model selection, and drone maintenance, to mitigate the safety risks. Finally, a post-hoc case study was investigated and presented in this article.
      Citation: Transportation Research Record
      PubDate: 2021-07-12T09:34:27Z
      DOI: 10.1177/03611981211017134
       
  • Use of the Alaska Geotechnical Asset Management Database in Evaluation of
           Retaining Structures After an Earthquake

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      Authors: John D. Thornley, Barry A. Benko, Alyson M. Mathers
      Abstract: Transportation Research Record, Ahead of Print.
      Since 2010, the Alaska Department of Transportation and Public Facilities, U.S., has been a leader in the development of geotechnical asset management (GAM) as part of a proactive approach to identify and rate the condition of geotechnical infrastructure. Efforts have included, for example, a retaining structure database that has cataloged retaining structures throughout Alaska. On November 30, 2018, a moment magnitude (MW) 7.1 earthquake struck southcentral Alaska, home of more than half of the state’s population. Damage to infrastructure was significant in several roadway corridors in the region. The GAM database was utilized as an important tool to assist in the identification of earthquake damaged retaining structures. Lessons learned from this effort are outlined in this paper. They include discussion on the elements of the database that were effective and others that may be improved on in the future. The information gathered from the field observations was also collected in such a manner that it could be added to the GAM database in the future as another snapshot in time for the retaining structures evaluated after the earthquake.
      Citation: Transportation Research Record
      PubDate: 2021-07-12T09:25:55Z
      DOI: 10.1177/03611981211016855
       
  • Live Road Condition Assessment with Internal Vehicle Sensors

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      Authors: Eyal Levenberg, Asmus Skar, Shahrzad M. Pour, Ekkart Kindler, Matteo Pettinari, Milena Bajic, Tommy S. Alstrøm, Uwe Schlotz
      Abstract: Transportation Research Record, Ahead of Print.
      Modern cars are equipped with many sensors that measure information about the vehicle and its surroundings. These measurements are therefore related to the ride-surface conditions over which the vehicle is passing. The paper commences by outlining a four-component vision for performing road condition evaluation based on in-vehicle sensor readings and subsequent feeding of pavement management systems (PMSs) with live condition information. This is expected to enrich the functionalities of PMSs, and ultimately lead to improved maintenance and repair decisions. Next the LiRA (Live Road Assessment) project—an ongoing proof-of-concept attempt to realize the vision components—is presented. The project elements and software architecture are described in detail, listing any assumptions, compromises, and challenges. LiRA involves a fleet of 400 electric cars operating in Copenhagen, both within the city streets and nearby highways. Sensor data collection is performed with a customized Internet of Things (IoT) device installed in the cars. Data processing and structuring involve new software tools for quality control, spatio-temporal interpolation, and map matching. A hybrid approach, combining machine learning models with physical (mechanics-based) models, is currently being applied to convert data into relevant information for PMSs. Based on the experience thus far with LiRA, the vision actualization is deemed achievable, workable, and up-scalable.
      Citation: Transportation Research Record
      PubDate: 2021-07-12T09:22:48Z
      DOI: 10.1177/03611981211016852
       
  • Distant Traffic Light Recognition Using Semantic Segmentation

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      Authors: Shota Masaki, Tsubasa Hirakawa, Takayoshi Yamashita, Hironobu Fujiyoshi
      Abstract: Transportation Research Record, Ahead of Print.
      Traffic light recognition is an important task for automatic driving support systems. Conventional traffic light recognition techniques are categorized into model-based methods, which frequently suffer from environmental changes such as sunlight, and machine-learning-based methods, which have difficulty detecting distant and occluded traffic lights because they fail to represent features efficiently. In this work, we propose a method for recognizing distant traffic lights by utilizing a semantic segmentation for extracting traffic light regions from images and a convolutional neural network (CNN) for classifying the state of the extracted traffic lights. Since semantic segmentation classifies objects pixel by pixel in consideration of the surrounding information, it can successfully detect distant and occluded traffic lights. Experimental results show that the proposed semantic segmentation improves the detection accuracy for distant traffic lights and confirms the accuracy improvement of 12.8 % over the detection accuracy by object detection. In addition, our CNN-based classifier was able to identify the traffic light status more than 30 % more accurately than the color thresholding classification.
      Citation: Transportation Research Record
      PubDate: 2021-07-12T09:19:22Z
      DOI: 10.1177/03611981211016467
       
  • Impact of Specialized Hauling Vehicles and Emergency Vehicles on Bridge
           Load Rating

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      Authors: Peng Lou, Chan Yang, Hani Nassif
      Abstract: Transportation Research Record, Ahead of Print.
      The Federal Highway Administration (FHWA) mandated states to adopt specialized hauling vehicles (SHVs) and emergency vehicles (EVs) in 2013 and 2016, respectively, in the load rating of bridges. Both the AASHTO single-unit trucks (SUs) and EVs are specially configured so that they may result in high load effects and can adversely affect bridge load rating factors. This paper investigates the impacts of rating these vehicles on the states’ bridge load ratings. An extensive literature review of the states’ load rating policies is performed. To determine whether any state can possibly be exempted from the new load ratings for SUs and EVs for Interstate highway bridges, the load effects of various state legal vehicles are analyzed and compared with those of SUs and EVs. The results of the study indicate the inevitability of executing the new load rating analysis for SUs and EVs for the vast majority of states. Weigh-in-motion data are processed to screen the potential EV traffic fleeting on the highway, and the calibrated live load factors are proposed for EVs accordingly. The load effects are found to be smaller than those FHWA originally assigned, improving the rating factors. Lastly, this paper proposes a screening tool to help state agencies to convert the known rating factors to the rating factors of SUs and EVs so that the load rating work can be prioritized for the bridges that are vulnerable to SUs and EVs.
      Citation: Transportation Research Record
      PubDate: 2021-07-09T06:43:49Z
      DOI: 10.1177/03611981211014531
       
  • Performance Evaluation of Asphalt Mixtures Modified with Recycled
           Polyethylene via the Wet Process

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      Authors: Fan Yin, Mawazo Fortunatus, Raquel Moraes, Michael D. Elwardany, Nam Tran, Jean-Pascal Planche
      Abstract: Transportation Research Record, Ahead of Print.
      The plastics and asphalt pavement industries have shown increasing interest in recycling waste plastics in asphalt because of potential environmental benefits. One approach to incorporating recycled plastics in asphalt is the wet process, which requires mechanical blending of recycled plastics into the asphalt binder as polymer modifiers. This study was aimed at exploring the use of recycled polyethylene (rPE) and a reactive elastomeric terpolymer (RET), which was used as a potential compatibilizer to rPE, for asphalt modification. Moreover, the study evaluated the impact of both modifiers on the bond strength characteristics of asphalt-aggregate systems as well as on the rutting and cracking resistance of asphalt mixtures. To this end, a battery of laboratory performance tests was conducted on asphalt mixtures containing binders: one neat; two rPE modified; and one styrene-butadiene-styrene modified. One rPE modified binder was formulated by adding 3% rPE to a PG 58-28 neat binder, while the other was modified with 3% rPE, RET, and polyphosphoric acid. Test results indicated that the rPE-plus-RET modified binder yielded an asphalt-aggregate system with enhanced moisture resistance, before and after oxidative aging. When compared with the control mixture, using rPE alone or rPE plus RET for asphalt modification significantly improved the rutting resistance. However, the rPE and rPE-plus-RET modified mixtures were found to be more susceptible to intermediate-temperature fatigue cracking at both short-term and long-term aging conditions. Finally, adding rPE or rPE plus RET did not have a significant impact on the mixture reflective cracking and thermal cracking resistance after long-term aging.
      Citation: Transportation Research Record
      PubDate: 2021-07-06T07:48:22Z
      DOI: 10.1177/03611981211011650
       
  • Corner Case Generation and Analysis for Safety Assessment of Autonomous
           Vehicles

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      Authors: Haowei Sun, Shuo Feng, Xintao Yan, Henry X. Liu
      Abstract: Transportation Research Record, Ahead of Print.
      Testing and evaluation is a crucial step in the development and deployment of connected and automated vehicles (CAVs). To comprehensively evaluate the performance of CAVs, it is necessary to test the CAVs in safety-critical scenarios, which rarely happen in a naturalistic driving environment. Therefore, how to purposely and systematically generate these corner cases becomes an important problem. Most existing studies focus on generating adversarial examples for perception systems of CAVs, whereas limited efforts have been put into decision-making systems, which is the highlight of this paper. As the CAVs need to interact with numerous background vehicles (BVs) for a long duration, variables that define the corner cases are usually high-dimensional, which makes the generation a challenging problem. In this paper, a unified framework is proposed to generate corner cases for decision-making systems. To address the challenge brought by high dimensionality, the driving environment is formulated based on the Markov decision process, and the deep reinforcement learning techniques are applied to learn the behavior policy of BVs. With the learned policy, BVs behave and interact with the CAVs more aggressively, resulting in more corner cases. To further analyze the generated corner cases, the techniques of feature extraction and clustering are utilized. By selecting representative cases of each cluster and outliers, the valuable corner cases can be identified from all generated corner cases. Simulation results of a highway driving environment show that the proposed methods can effectively generate and identify the valuable corner cases.
      Citation: Transportation Research Record
      PubDate: 2021-07-02T09:44:48Z
      DOI: 10.1177/03611981211018697
       
  • Probabilistic Situation Assessment for Intelligent Vehicles with Uncertain
           Trajectory Distribution

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      Authors: Heye Huang, Jinxin Liu, Xunjia Zheng, Wenjun Liu, Jianqiang Wang
      Abstract: Transportation Research Record, Ahead of Print.
      Situation assessment is crucial for intelligent vehicles, enabling detection of potential risks to dynamic and complex traffic environments. In this paper, we propose a unified framework that tackles the coupling relationships between traffic participants and quantifies the possible range of vehicle trajectory generation and the expected losses caused by risk source attributes in the driving process. We first apply the state space trajectory planning scheme based on a sampling algorithm to generate the path candidates; each feasible path is designed through a parametric cubic spline. Then, to evaluate the risk range in the driving process, we quantify the interaction of traffic participants, and employ the principle of least action to calculate the cost of each feasible path when achieving the destination. The probability distribution map, namely the possible range of driving trajectories, can be obtained based on the path cost. Furthermore, the vehicle-to-vehicle interaction is calculated based on the equivalent force, which estimates the expected accident losses. Finally, the vehicle trajectory prediction and the expected loss are combined to output the probabilistic situation assessment of intelligent vehicles. The algorithm is implemented in different scenarios and applied to the trajectory planning process. Results demonstrate that, compared with the classical situation assessment metric, the developed method can determine and accurately identify the influence range of driving risk in real-time, predict a dangerous situation earlier, and ensure the vehicle avoids obstacles in advance.
      Citation: Transportation Research Record
      PubDate: 2021-07-02T09:43:49Z
      DOI: 10.1177/03611981211019036
       
  • School Bus Routing Problem with a Mixed Ride, Mixed Load, and
           Heterogeneous Fleet

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      Authors: Mengyun Li, Joseph Y. J. Chow
      Abstract: Transportation Research Record, Ahead of Print.
      Special education students are usually routed on different buses than non-disabled general education students. To make the routes more efficient, this study proposes serving general students and special education students on the same bus at the same time (mixed ride) while allowing heterogeneous fleets and mixed loads. ESRI Location-Allocation tools and Google OR-Tools are used for bus stop selection, route generation, and bus stop optimization. Parallel cheapest insertion heuristic and metaheuristic, simulated annealing, are adopted to generate school bus routes. The effectiveness of the mixed ride approach is tested for three schools with 178 synthetic students’ locations data (including 12 with wheelchair) in New York City using a fleet of 14 buses spread over four types. The results show the mixed ride approach achieved 14.32% reduction in total travel distance and 10.46% reduction in total travel time. The mixed ride approach tends to return solutions with fewer vehicles and fewer bus stops, less average travel distance, and shorter average travel time.
      Citation: Transportation Research Record
      PubDate: 2021-07-02T09:35:07Z
      DOI: 10.1177/03611981211016860
       
  • Efficiency Comparison of Public Bike-Sharing Repositioning Strategies
           Based on Predicted Demand Patterns

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      Authors: Jung-Hoon Cho, Young-Hyun Seo, Dong-Kyu Kim
      Abstract: Transportation Research Record, Ahead of Print.
      Public bike-sharing systems are used worldwide, and the imbalance between supply and demand for bicycles and operational inefficiency is becoming increasingly severe. For a system to operate efficiently, it is necessary to relocate bicycles among rental stations to minimize a lack of bikes at the station causing unmet demand. Recent studies have presented various repositioning strategies for bike-sharing systems and compared their efficiency. However, little consideration has been paid to the strategy of the spatial and temporal patterns of bike-sharing demand and the inventory level. This study aims to analyze the spatiotemporal patterns of the forecasted demand for the bike-sharing system and to compare the efficiency of different repositioning strategies to choose the most efficient one. We use three repositioning strategies with different additional constraints related to unbalanced stations and present computational results with real data in Seoul. Two indices represent the temporal variation of predicted inventory at each station and the coefficients of the spatial variation for hourly unmet demand. Linear classifiers are derived by linear discriminant analysis to classify the efficiency of each strategy according to developed indices. The study reveals that adding constraints of imbalanced stations to the strategy according to the spatiotemporal characteristics of forecasted inventory can help to reduce unmet demand. The result of this study enables proactive decision-making using proposed indices in operating bike-sharing systems and contributes to improving the efficiency and reliability of systems.
      Citation: Transportation Research Record
      PubDate: 2021-07-02T09:33:46Z
      DOI: 10.1177/03611981211016859
       
  • Integrated Framework for Risk and Impact Assessment of Sediment Hazard on
           a Road Network

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      Authors: Johan Rose Santos, Varun Varghese, Makoto Chikaraishi, Tatsuhiko Uchida
      Abstract: Transportation Research Record, Ahead of Print.
      Road networks are highly vulnerable to risks stemming from both internal factors, such as the topological structure of the network, and external factors, such as natural disasters. The disruptions caused by these potential risk factors could result in severe physical and socio-economic losses. Therefore, understanding the impact and risk associated with road networks will be beneficial in reducing losses and helping to prepare better risk mitigation and management strategies. This study proposes an integrated approach to assess risk of sediment hazard on the road network by borrowing concepts from (a) transport vulnerability studies, (b) disaster risk assessment, and (c) spatial risk analysis and applying it to an identified vulnerable road network in Kure, Japan. The proposed risk framework holistically incorporates the processes of topological network vulnerability analysis, exposure spatial analysis, hazard occurrence probability estimation through binary logit regression, impact calculation using Monte Carlo simulation, and risk estimation. Using the recorded information on the rainfall event and sediment disaster that occurred in Hiroshima prefecture in July 2018, 12,000 possible multi-link disruption scenarios were simulated. Spatial distribution of the risk calculations helped to identify links with high probability of disruption and high impact, that is, high-risk links. The findings of this study may support policy decisions on road risk mitigation and recovery prioritization during disaster and road infrastructure investment through risk-benefit analysis.
      Citation: Transportation Research Record
      PubDate: 2021-07-02T09:32:28Z
      DOI: 10.1177/03611981211016462
       
  • Effect of the Employed Material Model on the Predicted Behaviour of
           Corrugated Metal Pipes

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      Authors: Hany El Naggar, Alex Campbell, Islam Ezzeldin
      Abstract: Transportation Research Record, Ahead of Print.
      In recent years, two-dimensional (2D) finite element modeling (FEM) has been used to explore how the structural integrity of a corrugated metal pipe (CMP) culvert is affected by simulation of its constituent components (i.e., the pipe metal, surrounding soil, or both). However, under various conditions, the nature of the problem is three-dimensional (3D) and 2D simulations may fall short of producing reasonable predictions. In this paper, the effect of various loading types on the structural response of round CMP culverts is investigated using 3D finite element (FE) models. The validity of the model was assessed by comparing the model output with previously published results from full-scale laboratory testing. The mechanical behaviour of real soil involves a significant degree of non-linearity. In soil-structure interaction problems such as the one considered here, it seems reasonable to expect that the non-linear behaviour of the soil, together with that of the soil-structure interface, would have a significant effect on the response of the structure. Furthermore, 2D models are limited in their ability to account for certain aspects of the actual, 3D problem. Such aspects include surface live load spreading through the cover soil and the structural behaviour of a corrugated pipe. This paper details the development of a comprehensive, 3D, non-linear FE model capable of simulating the behaviour of intact CMP culverts under backfilling and live loading. The analysis showed that the hyperbolic strain hardening model produced predicted response of the culvert that is very close to the obtained experimental data. However, the numerical results obtained using the Mohr-Coulomb or the linear elastic soil models were of less accuracy.
      Citation: Transportation Research Record
      PubDate: 2021-07-02T09:29:44Z
      DOI: 10.1177/03611981211016461
       
  • Investigating the Sensitivity of Electric Vehicle Out-of-Home Charging
           Demand to Changes in Light-Duty Vehicle Fleet Makeup and Usage: A Case
           Study for California 2030

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      Authors: Adam Wilkinson Davis, Gil Tal
      Abstract: Transportation Research Record, Ahead of Print.
      Accurately predicting the spatial distribution and charging demand of future electric vehicles (EVs) is vital to directing investment in charging infrastructure and planning policy interventions. To date, this expansion has been heavily concentrated in wealthy cities and suburbs, among commuters, and among households able to charge their vehicles at home. The expansion of EV ownership will include both changes in where the vehicles are owned and how they are used and charged. This paper demonstrates methods to predict where the expansion of EV ownership is most likely to occur under current market characteristics and allows for testing of scenarios of future characteristics. These methods are demonstrated with an analysis of California, U.S., using a scenario of 4 million battery electric vehicles (BEVs) and 1 million plug-in hybrid electric vehicles (PHEVs), to match the state’s goal of 5 million zero-emission vehicles by 2030. These projections are combined with a model for charging behavior to generate scenarios of demand for charging away from home under various fleet characteristics and identify areas of the state with the greatest need for infrastructure investment.
      Citation: Transportation Research Record
      PubDate: 2021-07-02T09:28:37Z
      DOI: 10.1177/03611981211016459
       
  • Impact of Turning Lane Storage Length and Turning Proportions on
           Throughput at Oversaturated Signalized Intersections

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      Authors: A. M. Tahsin Emtenan, Christopher M. Day
      Abstract: Transportation Research Record, Ahead of Print.
      During oversaturated conditions, common objectives of signal timing are to maximize vehicle throughput and manage queues. A common response to increases in vehicle volumes is to increase the cycle length. Because the clearance intervals are displayed less frequently with longer cycle lengths and fewer cycles, more of the total time is used for green indications, which implies that the signal timing is more efficient. However, previous studies have shown that throughput reaches a peak at a moderate cycle length and extending the cycle length beyond this actually decreases the total throughput. Part of the reason for this is that spillback caused by the turning traffic may cause starvation of the through lanes resulting in a reduction of the saturation flow rate within each lane. Gaps created by the turning traffic after a lane change may also reduce the saturation flow rate. There is a relationship between the proportions of turning traffic, the storage length of turning lanes, and the total throughput that can be achieved on an approach for a given cycle length and green time. This study seeks to explore this relationship to yield better signal timing strategies for oversaturated operations. A microsimulation model of an oversaturated left-turn movement with varying storage lengths and turning proportions is used to determine these relationships and establish a mathematical model of throughput as a function of the duration of green, storage length, and turning proportion. The model outcomes are compared against real-world data.
      Citation: Transportation Research Record
      PubDate: 2021-07-01T01:56:41Z
      DOI: 10.1177/03611981211017139
       
  • Evaluation of a New Intersection Design, “Shifting Movements”

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      Authors: Ma’en Mohammad Ali Al-Omari, Mohamed Abdel-Aty
      Abstract: Transportation Research Record, Ahead of Print.
      Several unconventional designs have been suggested to enhance traffic operation and safety at intersections. However, the operational benefits of implementing some of them are achieved only under certain traffic conditions. For instance, the operational performance of the restricted crossing U-turn (RCUT) intersection design manifests only under highly unbalanced traffic conditions. The RCUT intersection outperforms conventional intersections that are subjected to high major traffic and light minor traffic volumes, while its operational performance fades at intersections with moderate to heavy minor road traffic. In this technical paper, a new innovative four-leg intersection design has been proposed to replace the RCUT intersection under moderate and heavy minor road traffic volumes. The new intersection design which has been named the “Shifting Movements” (SM) intersection has a low number of conflict-points compared with conventional intersections, but similar to the RCUT intersection. Therefore, similar safety benefits are expected to be achieved by the implementation of the SM intersection. Operational evaluations and comparisons between conventional, RCUT, and SM intersections have been conducted in the microscopic simulation environment. Different traffic volume levels and left-turn proportions have been assumed to represent the peak hour with moderate to high left-turn traffic. The results indicate that the SM intersection design significantly outperforms conventional and RCUT intersections that are subjected to high traffic volumes in average control delay and throughput.
      Citation: Transportation Research Record
      PubDate: 2021-06-18T11:46:02Z
      DOI: 10.1177/03611981211015990
       
  • Critical State Model of Sand-Tire Derived Aggregate Mixtures Based on
           Triaxial Tests

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      Authors: Adolfo Foriero, Nima Ghafari
      Abstract: Transportation Research Record, Ahead of Print.
      This study is part of an environmental experimental program on the use of scrap automobile tires for geotechnical applications. Different types of laboratory tests were conducted to determine the elastic, plastic, and creep parameters of tire derived aggregate (TDA)-sand granulated mixtures. However, this paper emphasizes the plasticity parameters via the development of a critical state model based on the results of triaxial tests. This was attained by considering loose sand specimens, at a predetermined TDA volumetric content, subject to three different confining pressures under a constant axial displacement rate. The calculated deviatoric stress versus axial strain curves, obtained via the modified Cam Clay model, captured the non-linear elastoplastic response obtained in the tests. Results indicated that the level of the shear strength is highly dependent on critical state friction angle which in turn depends on the TDA content. For the loose TDA-sand mixtures used in the present study, the effect of the TDA content demonstrates a reinforcement of the sand matrix. However this reinforcement diminishes as the TDA content increases.
      Citation: Transportation Research Record
      PubDate: 2021-06-18T02:23:22Z
      DOI: 10.1177/0361198121997837
       
  • Impact of Cooperative Adaptive Cruise Control on a Multilane Highway under
           a Differentiated Per-Lane Speed Limit Policy

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      Authors: Zhe Xiao, Xiaoyu Guo, Xiucheng Guo, Yi Li
      Abstract: Transportation Research Record, Ahead of Print.
      Cooperative adaptive cruise control (CACC) has drawn wide attention in recent years for its potential throughput benefit, as it is a promising intermediate technology to the highly connected and automated vehicles. The impact of CACC on multilane highways has been the subject of several studies, but they assumed traffic under a uniform speed limit. Recent research has revealed that traffic performs differently under a differentiated per-lane speed limit (DPLSL) policy with heavy vehicle (HV) restricted lanes. Whether the benefits of CACC still remain under a DPLSL policy has not been explored. This study developed cellular automaton models to incorporate CACC-equipped and non-equipped vehicles (i.e., passenger cars, HVs) on a two-way eight-lane highway with a DPLSL. Results shown throughputs by lane increase up to 78.5% as the CACC car market penetration rate (MPR) rises. Such increases became sharper (i.e., ≥10%) for inner lanes (i.e., HV restricted lanes) and outer lanes after reaching a 40% and a 60% CACC car MPR, separately. Moreover, HVs induced a 1.5% to 15.7% throughput reduction across lanes even under higher CACC car MPRs (i.e., 60%, 80%). This DPLSL policy may cause the lanes to experience a throughput penalty when they are adjacent to lanes with a different speed limit as the MPR of CACC cars rises. Lastly, in traffic with a 60% CACC car MPR, increases are brought further by considering 10% of HV with CACC, especially on those HV non-restricted lanes. The study is helpful for policy makers to further prepare for the prevalence of CACC in the forthcoming years.
      Citation: Transportation Research Record
      PubDate: 2021-06-11T07:40:09Z
      DOI: 10.1177/03611981211011475
       
  • Driver Response to a Dynamic Speed Feedback Sign on Freeway Exit Ramps
           Based on Sign Location, Interchange Type, and Time of Day

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      Authors: Md Shakir Mahmud, Matthew Motz, Travis Holpuch, Jordan Hankin, Anthony J. Ingle, Timothy J. Gates, Peter T. Savolainen
      Abstract: Transportation Research Record, Ahead of Print.
      A series of field evaluations was performed at three freeway interchange ramps in Michigan that possessed significant horizontal curvature to assess the impacts of a dynamic speed feedback sign (DSFS) on driver speed selection and brake response while approaching and entering the ramp curve. A DSFS with a 15 in. full-matrix display was temporarily installed at each of the three exit ramp locations. The sign was programmed to display the same feedback message at each location, which included the speed number for all approaching vehicles, which alternated with a “Slow Down” message for vehicles approaching above 40 mph. The effectiveness of the feedback sign was tested across various sign locations (at the point of curvature versus 350 ft upstream), interchange types (system versus service), time of day (peak versus off-peak), light conditions (daylight versus darkness), and vehicle types (passenger vehicles versus trucks). Compared with the pre-DSFS site condition, the DSFS reduced curve entry speeds and improved brake response at two of the three ramp locations. In general, the greatest beneficial effects on driver behavior were achieved when the DSFS was positioned at the point of curvature, during which curve entry speeds were reduced by approximately 2 mph. These findings were consistent between the system interchanges and service interchanges, and across all vehicle types. The DSFS was also found to be most effective during daytime off-peak periods compared with peak periods and at night. Further evaluation of DSFS at additional ramp locations, and considering an expanded set of conditions, is recommended.
      Citation: Transportation Research Record
      PubDate: 2021-06-11T07:39:58Z
      DOI: 10.1177/03611981211015250
       
  • Exploratory Study of Flexural Performance of Mechanically Recycled Glass
           Fiber Reinforced Polymer Shreds as Reinforcement in Cement Mortar

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      Authors: Md Mostofa Haider, Somayeh Nassiri, Karl Englund, Hui Li, Zhen Chen
      Abstract: Transportation Research Record, Ahead of Print.
      Millions of tons of glass fiber reinforced polymer (GFRP) waste have been steadily generated from end-of-life wind turbine blades and many other GFRP composites prevalent in everyday life, with limited reuse options. Recycled GFRP (rGFRP) by mechanical processing could be used in mortar and concrete as fibers or fillers. Maintaining the composite nature of rGFRP with a high fiber content is paramount to increased mechanical properties for concrete. In this study, high-modulus rGFRP particles were produced in three small, medium, and large relative sizes by hammer milling and screening. Small and medium rGFRPs were used in 1, 2, 3%, and large rGFRP in 1, 2, 3, 5, and 7% volume replacing sand in mortar. Almost all rGFRP-mortars showed significant improvement in flexural strength with their high modulus. All size groups of rGFRP progressively showed higher fracture toughness at higher amounts. Within the large group, 5 and 7%Vol had flexural toughness of about 2.00J compared with 0.75J of 3%Vol. Large rGFRP at 5 and 7%Vol offered nearly 60% and 70% 28 day equivalent flexural ratio. Micrographs of rGFRP–matrix interfaces from fracture faces showed rGFRP was well embedded within the matrix, provided bridging and deflecting of microcracks, and failed in pullout or rupture modes. Fly ash and silica fume had a positive synergy with 3%Vol large rGFRP and improved its flexural toughness from 0.75J to 1.12 and 1.00J, respectively. The investigated recycling process and sizes of rGFRP shreds showed great promise in this exploratory study and are recommended for further evaluation for highway and bridge concrete.
      Citation: Transportation Research Record
      PubDate: 2021-06-11T07:39:54Z
      DOI: 10.1177/03611981211015246
       
  • Assessment of Queue Warning Application on Signalized Intersections for
           Connected Freight Vehicles

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      Authors: Sara Bashir, Milan Zlatkovic
      Abstract: Transportation Research Record, Ahead of Print.
      Connected vehicle (CV) systems are at the core of intelligent transportation systems (ITS) for their capability to support a variety of ITS applications and to unite vehicles and infrastructure elements into a well-integrated transportation system. CV refers to vehicles that exchange information with each other and with the infrastructure. The queue warning application (Q-WARN) uses CV technologies to allow vehicles within the queue to broadcast their queued status information automatically to upstream vehicles and to infrastructure. Queue warnings are sent to oncoming vehicles to prevent rear-end or other secondary collisions. This paper focuses on Q-WARN applications for freight vehicles at signalized intersections adjacent to I-80 in Wyoming, which are characterized by heavy truck traffic. The algorithms use the latitude/longitude coordinates of freight CVs and intersections to form a communication link and to share information. Tests were performed in VISSIM microsimulation with Econolite ASC/3 software-in-the-loop controller emulator for different CV market penetration rates. Three locations in Wyoming were used as test-bed cases. The developed Q-WARN algorithms are successful in reducing vehicle delays by an average of 2% to 5%. Time to collision (TTC) significantly increased with an increase in CV rates, by two to five times. The abundance of information obtained from CVs can be used further to enhance signal control algorithms. The developed algorithms can easily be implemented in the field, since they use existing CV communication protocols and signal control logic.
      Citation: Transportation Research Record
      PubDate: 2021-06-11T07:39:43Z
      DOI: 10.1177/03611981211015247
       
  • Big Data Insights into Container Vessel Dwell Times

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      Authors: Daniel Smith
      Abstract: Transportation Research Record, Ahead of Print.
      Analysis of automatic identification system (AIS) vessel call records can greatly improve our understanding of container vessel dwell times when coupled with information on port volumes and vessel schedules. Port productivity discussions often use vessel time in port—referred to as dwell time, turnaround time, or berth time—as a primary metric. This emphasis implies a need to understand the factors that determine dwell time, especially in port comparisons. Previous dwell time analyses have been handicapped by limited data. This analysis differs in that it uses a multiyear, multiport database covering all relevant vessel calls at major continental U.S. container ports (Baltimore, Boston, Charleston, Houston, Jacksonville, Long Beach, Los Angeles, Miami, Mobile, New Orleans, Northwest Seaport Alliance, New York–New Jersey, Oakland, Palm Beach, Philadelphia, Port Everglades, Savannah, Virginia, and Wilmington, NC), and by including vessel schedules and seasonality. The analysis indicated a much stronger association of dwell time with expected cargo volume at each call than with vessel capacity, and expected cargo volumes helped explain port dwell time differences. The analysis also found that vessel schedules may be the primary determinants of dwell time, and that schedule adherence may thus be equally important as dwell time per se. Seasonality also affected container vessel dwell time, but that influence may be complex as both weather conditions and seasonal cargo peaks probably affect the outcomes. Promising avenues for future research lie in merging AIS vessel call records with other data sets that, unfortunately, may not yet exist or be accessible.
      Citation: Transportation Research Record
      PubDate: 2021-06-10T09:37:28Z
      DOI: 10.1177/03611981211015248
       
  • Empirical Estimation of Shortest Route Length along U.S. Interstate
           Highways Based on Great Circle Distance

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      Authors: Nawei Liu, Fei Xie, Zhenhong Lin, Mingzhou Jin
      Abstract: Transportation Research Record, Ahead of Print.
      In this study, 98 regression models were specified for easily estimating shortest distances based on great circle distances along the U.S. interstate highways nationwide and for each of the continental 48 states. This allows transportation professionals to quickly generate distance, or even distance matrix, without expending significant efforts on complicated shortest path calculations. For simple usage by all professionals, all models are present in the simple linear regression form. Only one explanatory variable, the great circle distance, is considered to calculate the route distance. For each geographic scope (i.e., the national or one of the states), two different models were considered, with and without the intercept. Based on the adjusted R-squared, it was observed that models without intercepts generally have better fitness. All these models generally have good fitness with the linear regression relationship between the great circle distance and route distance. At the state level, significant variations in the slope coefficients between the state-level models were also observed. Furthermore, a preliminary analysis of the effect of highway density on this variation was conducted.
      Citation: Transportation Research Record
      PubDate: 2021-06-10T09:37:01Z
      DOI: 10.1177/03611981211015251
       
  • Impact of One-Way Streets and Contraflow on Low-Stress Bicycle Network
           Connectivity

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      Authors: Theja Putta, Peter G. Furth
      Abstract: Transportation Research Record, Ahead of Print.
      One-way restrictions on local streets, which tend to have low traffic stress, can create a significant barrier to low-stress cycling. Contraflow, a treatment that undoes one-way restrictions on bike travel, has the potential to improve low-stress connectivity. Although contraflow is applied routinely in the Netherlands and Belgium, it has been sparingly applied in the United States. We propose refined measures of connectivity and accessibility that account for one-way restrictions by requiring a low-stress round trip path between origins and destinations. Different methods of associating origin–destination demand from polygons with a street network were analyzed. These methods are particularly important where there are one-way restrictions and irregular street networks because of the assumptions they entail in relation to first- and last-segment travel. In a case study of Greater Boston, we found that with the current bike network, low-stress connectivity between homes and jobs would increase from 1.2% to 8.7% if one-way restrictions on local streets were eliminated. We also found that even with a dense mesh of low-stress main bike routes, connectivity would still be 16% lower without contraflow on local streets than with. These results suggest that creating a network of main bike routes is not always enough; it is also important to provide contraflow on local streets. The Boston study also found that providing contraflow on selected links representing only 3% of local one-way street mileage delivered 40% of the connectivity impact of universal contraflow. Based on this finding, a method is proposed for prioritizing streets for contraflow conversion.
      Citation: Transportation Research Record
      PubDate: 2021-06-09T10:12:56Z
      DOI: 10.1177/03611981211014893
       
  • Development of a Performance-Related Framework for Asphalt Mixture Design
           for the Illinois Tollway

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      Authors: Behnam Jahangiri, Punyaslok Rath, Hamed Majidifard, William G. Buttlar
      Abstract: Transportation Research Record, Ahead of Print.
      Various agencies have begun to research and introduce performance-related specifications (PRS) for the design of modern asphalt paving mixtures. The focus of most recent studies has been directed toward simplified cracking test development and evaluation. In some cases, development and validation of PRS has been performed, building on these new tests, often by comparison of test values to accelerated pavement test studies and/or to limited field data. This study describes the findings of a comprehensive research project conducted at Illinois Tollway, leading to a PRS for the design of mainline and shoulder asphalt mixtures. A novel approach was developed, involving the systematic establishment of specification requirements based on: 1) selection of baseline values based on minimally acceptable field performance thresholds; 2) elevation of thresholds to account for differences between short-term lab aging and expected long-term field aging; 3) further elevation of thresholds to account for variability in lab testing, plus variability in the testing of field cores; and 4) final adjustment and rounding of thresholds based on a consensus process. After a thorough evaluation of different candidate cracking tests in the course of the project, the Disk-shaped Compact Tension—DC(T)—test was chosen to be retained in the Illinois Tollway PRS and to be presented in this study for the design of crack-resistant mixtures. The DC(T) test was selected because of its high degree of correlation with field results and its excellent repeatability. Tailored Hamburg rut depth and stripping inflection point thresholds were also established for mainline and shoulder mixes.
      Citation: Transportation Research Record
      PubDate: 2021-06-09T10:12:39Z
      DOI: 10.1177/03611981211014886
       
  • Approaches and Barriers to Addressing Equity in Transportation:
           Experiences of Transportation Practitioners

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      Authors: Kaylla Cantilina, Shanna R. Daly, Matthew P. Reed, Robert C. Hampshire
      Abstract: Transportation Research Record, Ahead of Print.
      The importance of advancing transportation equity has become more visible as other structural inequities in our society have received increasing attention. Articulating approaches that practitioners use to address equity in their work, including experience-based strategies and research-developed equity metrics, contribute to supporting the achievement of transportation equity goals. However, a gap exists between knowing these approaches and integrating them into regular professional practice, in part because of barriers that span across different transportation-related contexts. To investigate practitioners’ approaches to transportation equity, as well as barriers they encounter in trying to achieve improved equity, interviews were conducted with 59 transportation practitioners from the public, private, non-profit, and academic sectors. Findings revealed that a majority of the transportation practitioners in the study engaged in addressing equity in their work, including through collaborating with other organizations and sectors, integrating non-transportation-related data, and considering the contextual needs of vulnerable communities. They identified key barriers to their implementation of transportation equity approaches, including the lack of sufficient and quality equity-related data, challenges with accessing and collecting data, and a lack of standards and metrics for measuring equity-related outcomes. These findings can guide work that supports the explicit integration of transportation equity approaches into practitioners’ practices.
      Citation: Transportation Research Record
      PubDate: 2021-06-08T11:55:48Z
      DOI: 10.1177/03611981211014533
       
  • Using GTFS to Calculate Travel Time Savings Potential of Bus Preferential
           Treatments

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      Authors: Daniel Arias, Kara Todd, Jennifer Krieger, Spencer Maddox, Pearse Haley, Kari Edison Watkins, Simon Berrebi
      Abstract: Transportation Research Record, Ahead of Print.
      Dedicated bus lanes and other transit priority treatments are a cost-effective way to improve transit speed and reliability. However, creating a bus lane can be a contentious process; it requires justification to the public and frequently entails competition for federal grants. In addition, more complex bus networks are likely to have unknown locations where transit priority infrastructure would provide high value to riders.This analysis presents a methodology for estimating the value of bus preferential treatments for all segments of a given bus network. It calculates the passenger-weighted travel time savings potential for each inter-stop segment based on schedule padding. The input data, ridership data, and General Transit Feed Specification (GTFS) trip-stop data are universally accessible to transit agencies.This study examines the 2018 Metropolitan Atlanta Rapid Transit Authority (MARTA) bus network and identifies a portion of route 39 on Buford Highway as an example candidate for a bus lane corridor. The results are used to evaluate the value of time savings to passengers, operating cost savings to the agency, and other benefits that would result from implementing bus lanes on Buford Highway.This study does not extend to estimating the cost of transit priority infrastructure or recommending locations based on traffic flow characteristics. However, it does provide a reproducible methodology to estimate the value of transit priority treatments, and it identifies locations with high value, all using data that are readily available to transit agencies. Conducting this analysis provides a foundation for beginning the planning process for transit priority infrastructure.
      Citation: Transportation Research Record
      PubDate: 2021-06-07T05:11:37Z
      DOI: 10.1177/03611981211009226
       
  • Peer Review: The Volpe/Federal Highway Administration National Vehicle
           Miles Traveled Forecasting Models

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      Authors: Jeffrey Cohen, Sharada Vadali, Michael F. Lawrence, Shikha Dave, Clayton Clark
      Abstract: Transportation Research Record, Ahead of Print.
      This paper describes the findings of an independent peer review of the modeling tools used by the Volpe National Transportation Systems Center to forecast national vehicle miles traveled (VMT) over the next 30 years. Overall, the VMT forecasting models, which use autoregressive distributed lag models for light-duty vehicle, single-unit truck, and combination truck VMT, work well to estimate travel demand. All model estimations were reviewed, and all models perform well against several validation and testing techniques. The study team was supported by an expert panel selected from academia, government, and industry with experience in econometric methods, transportation and economic data, and modeling methods. The panel reviewed model documentation as well as the report assessing the VMT forecasting models and provided insight into alternative model research. The paper is an effort to synthesize the approaches and the validation methods used. A complementary literature search was also conducted to test the validity and comparability of several estimated variable coefficients. The paper concludes by summarizing the key findings and making recommendations on future model improvements.
      Citation: Transportation Research Record
      PubDate: 2021-06-05T06:30:11Z
      DOI: 10.1177/03611981211011997
       
  • Experimental Study on the Relationship between Fatigue and Unsafe Behavior
           of Urban Rail Transit Drivers

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      Authors: Xing-da You, Lin Zhu, Zhi-gang Liu, Yuan-chun Huang
      Abstract: Transportation Research Record, Ahead of Print.
      In recent years there has been rapid development of urban rail transit in China. The train driver, as the direct controller of the train, plays an important role in subway operation, and their driving performance directly determines whether the train is safe or not. To explore the relationship between fatigue and unsafe behavior, a simulated driving experiment was designed to record the train driver’s behavior under fatigue and normal state. The changes of operation accuracy and timeliness are used in combination to reflect the train driver’s unsafe behavior. The results show that when the train driver is in a state of fatigue, their operation accuracy is 126% lower than in the normal state. In the operation timeliness index, the time required for the train driver to react and complete the action is 28.13% and 17.7% longer than that in the normal state. It is concluded that fatigued driving can easily lead to unsafe behavior which then leads to potential safety accidents.
      Citation: Transportation Research Record
      PubDate: 2021-06-05T06:29:49Z
      DOI: 10.1177/03611981211014888
       
  • Chemo-Rheological Characterization of the Effect of Iran Rock Asphalt on
           the Performance of Waste Bio-Oil Modified Asphalts

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      Authors: Jianmin Ma, Guoqiang Sun, Daquan Sun, Mingjun Hu, Tong Lu
      Abstract: Transportation Research Record, Ahead of Print.
      This study aims to investigate the effect of Iran rock asphalt (IRA) on the rheological performance of waste bio-oil modified asphalt (WBMA). Three kinds of WBMA with bio-oil origins including soybean oil residue, castor oil residue, and waste cooking oil residue were blended with different dosages of IRA. The high-temperature performance of the three blended asphalt binders was evaluated using the temperature sweep test and multiple stress creep recovery (MSCR) test. The effect of IRA on the fatigue performance and low-temperature cracking resistance of the three WBMAs was evaluated using the linear amplitude sweep (LAS) test and the bending beam rheometer (BBR) test. A gel permeation chromatography (GPC) test was conducted to further understand the contribution of IRA to the overall rheological performance of different WBMAs. Results indicated that the high-temperature performance of the three WBMAs was enhanced significantly with the increase of IRA content. The predicted fatigue life from the LAS test showed that the incorporation of IRA extended the fatigue life of the three WBMAs at a lower strain level, while this effect was not profound at a higher strain level. Results from BBR test showed that IRA may increase the risk of low-temperature cracking and that the dosage of IRA should be limited to fulfill the requirements of the low-temperature performance. The GPC analysis revealed that the enhanced high-temperature performance and reduced low-temperature cracking resistance of WBMAs modified with IRA was mainly a result of the increased asphaltene concentration.
      Citation: Transportation Research Record
      PubDate: 2021-06-03T07:09:37Z
      DOI: 10.1177/03611981211015989
       
  • Development of a Non-Gating Guardrail Terminal

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      Authors: Kevin D. Schrum, Kenneth Walls, Joseph Schwertz, Blake Feltman, Dakotah Sicking, Dean L. Sicking
      Abstract: Transportation Research Record, Ahead of Print.
      Guardrail terminals have evolved to the point where they absorb energy while utilizing tension in the rail to countermand the compression. However, non-gating terminals have yet to be developed. In the present study, the possibility of a non-gating guardrail terminal was investigated. Specifically, the combination of lateral and longitudinal forces that produce non-gating performance were determined from computer simulation. Next, a prototype terminal was crash tested at the research team’s laboratory. A terminal head was designed to deform the guardrail, and its internal structure was adjustable to control the longitudinal force. Posts were designed to control lateral forces by modifying their section modulus. This controlled the force at which the posts buckled in response to a collision. A prototype was subjected to two 15° crash tests using an SUV and a small car. In both tests, the kinetic energy of the test vehicle was fully absorbed and the Manual for Assessing Safety Hardware (MASH) criteria would have been met. Neither vehicle passed beyond the terminal head, making these test results the first of their kind.
      Citation: Transportation Research Record
      PubDate: 2021-06-03T07:06:57Z
      DOI: 10.1177/03611981211014890
       
  • Market-Segmentation Study of Future and Potential Users of the New Réseau
           Express Métropolitain Light Rail in Montreal, Canada

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      Authors: Nicolette Dent, Leila Hawa, James DeWeese, Rania Wasfi, Yan Kestens, Ahmed El-Geneidy
      Abstract: Transportation Research Record, Ahead of Print.
      Goals for public transit agencies and new public transport infrastructure projects include attracting new riders and retaining existing system users. An understanding of the public transport market and its preferences, habits, and attitudes can help public transit agencies reach these goals by shedding light on how to increase customer satisfaction. To understand potential users of one of Montreal’s most recent major transport projects, the Réseau express métropolitain (REM), we conducted a survey in Fall 2019 while the light-rail system was under construction. Drawing on vetted transport market-segmentation frameworks, this study employs an exploratory factor analysis to reveal factors that affect respondents’ propensity to use the REM. A k-means cluster test is applied to the factors to articulate market segments. The analysis returned four clusters that form a clear spectrum of least likely to most likely REM users: car-friendly non-users, urban core potential users, transit-friendly users, and leisure and airport users. Positive opinion, proximity, and desire to use the REM for leisure or non-work trips are three key characteristics of likely users. There is a visible relationship between clusters who are likely to use the REM and clusters who agree that the REM will benefit their neighborhood. Improving people’s perception of the potential benefit of the REM to their neighborhood, better accommodating leisure use, emphasizing and communicating appealing destinations, and highlighting transit connections are four core ways that planners could work to potentially increase the number of people who are likely to use the REM.
      Citation: Transportation Research Record
      PubDate: 2021-06-03T07:05:42Z
      DOI: 10.1177/03611981211014528
       
  • Impact of Concrete Mix Ingredients and Surface Treatments on Epoxy Overlay
           Performance

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      Authors: Abul Fazal Mazumder, Harsha Amunugama, Upul Attanayake
      Abstract: Transportation Research Record, Ahead of Print.
      Epoxy overlays are applied on bridge decks after curing concrete in patches and repairs for 28 days. A tensile bond pull-off strength of at least 250 pounds per square inch (psi) is expected from a properly applied overlay. Even though the overlay performance at room temperature is mostly satisfactory, the performance at elevated temperatures is not convincing. The degradation of mechanical and adhesion properties of epoxy, shear stress at the concrete/overlay interface caused by thermal incompatibility, and the interface moisture vapor pressure are the commonly cited parameters for poor bond strength at elevated temperatures. A combined effect of these parameters results in the most unfavorable failure mode (which is bond failure at the concrete/overlay interface) at a strength lower than the specified limit of 250 psi. The moisture migration through concrete depends on many factors including moisture content along the depth of concrete, pore microstructure, exposure condition, and drying period. This study investigated the impact of concrete mix ingredients and surface treatments on the thin epoxy overlay bond strength. The results show that the use of concrete mixes with slag and penetrating sealant pretreatment improves the bond strength.
      Citation: Transportation Research Record
      PubDate: 2021-06-01T01:41:06Z
      DOI: 10.1177/03611981211014887
       
  • Performance-Based Approach for Deciding the Age of New Concrete for Thin
           Epoxy Overlay Application

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      Authors: Upul Attanayake, Abul Fazal Mazumder
      Abstract: Transportation Research Record, Ahead of Print.
      A thin epoxy overlay application is a capital preventive maintenance activity. Epoxy overlays reduce the rate of chloride ion ingress and extend bridge deck service life. Highway agency policies and manufacturer specifications require maintaining a 28-day curing period (7-day wet and 21-day dry curing) before the application of an epoxy overlay on bridge decks requiring new concrete for patches and repairs. Consequently, the contractors wait for 28 days to apply an epoxy overlay. Delaying application time increases project completion time and the cost of construction and mobility. The suitability of new concrete to receive epoxy overlays and the performance of overlays depend on several parameters including concrete strength, moisture, and tendency to crack. Such parameters depend on concrete mixture ingredients and wet and dry curing periods. This paper presents a performance-based procedure for evaluating the possibility of reducing the 28-day waiting period for a thin epoxy overlay application on new concrete. An experimental program was developed and executed to evaluate the impact of epoxy overlay application parameters and overlay performance using a tensile bond pull-off strength test. The results support developing a performance-based procedure for deciding on the suitable age of new concrete to receive a thin epoxy overlay. The pull-off bond strength of epoxy overlays applied at 7, 14, and 21 days, following a 7-day moist curing, shows the possibility of applying an epoxy overlay before the end of the 28-day curing period stipulated in the current specifications.
      Citation: Transportation Research Record
      PubDate: 2021-06-01T01:37:45Z
      DOI: 10.1177/03611981211014530
       
  • Microtransit Has the Potential to Flip Transit on Its Head

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      Authors: Jerome Mayaud, Francesca Ward, Josh Andrews
      Abstract: Transportation Research Record, Ahead of Print.
      Fixed-route transit in the U.S.A. is facing stiff competition from more convenient mobility options. Microtransit—shared transportation that offers dynamic routing and scheduling to efficiently match demand—is emerging as an ally to fixed-route services. However, its positive impacts are too often constrained by the politics and economics imposed by existing transit infrastructure. This paper proposes a solution that “flips transit on its head.” By rapidly prototyping microtransit services across cities and analyzing supply-demand mismatches, it is possible to launch truly data-driven transit services. To illustrate the framework, a unique dataset generated from a year of Dallas Area Rapid Transit’s GoLink service, one of the largest on-demand microtransit services in North America, is used. Mapping and machine learning are combined to empower planners to “join the dots” when (re)designing fixed-route transit lines. It is shown that microtransit should not simply fill in the gaps left by inefficiently scheduled bus routes: by incorporating it fully into their planning processes, cities and transit agencies could dramatically reverse the fortunes of public transit.
      Citation: Transportation Research Record
      PubDate: 2021-06-01T01:35:44Z
      DOI: 10.1177/03611981211014523
       
  • Multi-Objective Optimization for Skip-Stop Strategy Based on Smartcard
           Data Considering Total Travel Time and Equity

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      Authors: Sang-Wook Han, Eun Hak Lee, Dong-Kyu Kim
      Abstract: Transportation Research Record, Ahead of Print.
      With the rise of urban sprawl, urban railways extend out further to the city’s outer district, installing additional stations. Passengers who travel from the outer district to the center of the city therefore experience long travel times. Although skip-stop strategy helps save total travel time, deviation of travel time among all origin–destination pairs may be increased, leading to equity problems. This study aims to minimize the inequity and total travel time through train stop planning and train scheduling. A coefficient of variation is adopted as a measure of inequity. The problem is formulated as a multi-objective mixed integer nonlinear programming model. Origin–destination demand is extracted from smartcard data and a case study of four urban railway lines in Seoul is conducted. The results indicate that the number of transfer stations for equity-oriented skip-stop strategy is smaller than that for total-travel-time-oriented skip-stop strategy. We also discover that as the number of transfer stations rises, inequity increases and total travel time is reduced. For skip-stop strategy considering total travel time and equity simultaneously, average total travel time and the average deviation are reduced by up to 10.3% and 10.6%, respectively, compared with those of all-stop strategy. We analyze the gradient of Pareto optimal sets to find out which factors (equity or total travel time) are more significant. Skip-stop strategy on lines 5 and 9 can be designed based on equity, while line 4 can be planned based on total travel time.
      Citation: Transportation Research Record
      PubDate: 2021-06-01T01:33:37Z
      DOI: 10.1177/03611981211013044
       
  • Field Theory for Some Traffic Phenomena and Fundamental Diagram

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      Authors: Daiheng Ni
      Abstract: Transportation Research Record, Ahead of Print.
      A fundamental diagram consists of a scatter of traffic flow data sampled at a specific location and aggregated from vehicle trajectories. These trajectories, if presented equivalently, constitute a microscopic version of the (conventional) fundamental diagram. The cross-reference between vehicle trajectories and the microscopic fundamental diagram provides details of vehicle motion dynamics which allow causal-effect analysis on some traffic phenomena and further reveal the microscopic basis of the conventional fundamental diagram. This observation inspires theoretical modeling by a microscopic approach to address traffic phenomena and the conventional fundamental diagram. Derived from the field theory of traffic flow, the longitudinal control model is capable of serving the purpose without the modifications or exceptions used by other approaches.
      Citation: Transportation Research Record
      PubDate: 2021-05-31T06:50:38Z
      DOI: 10.1177/03611981211006422
       
  • Investigating the Preferences of Local Residents toward a Proposed Bus
           Network Redesign in Chattanooga, Tennessee

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      Authors: Abubakr Ziedan, Cassidy Crossland, Candace Brakewood, Philip Pugliese, Harrison Ooi
      Abstract: Transportation Research Record, Ahead of Print.
      Many transit agencies are considering or implementing bus network redesigns. Considering this growing trend, this study investigates the preferences of local residents for a proposed bus network redesign in Chattanooga, Tennessee. The study uses survey data collected by the Chattanooga Area Regional Transportation Authority and its partners as part of a bus network redesign planning process. Using the survey data, three logit models are estimated to explore preferences between different bus network redesign philosophies, transit network improvements, and willingness to pay for proposed transit improvements and expansion. There are three main findings. First, respondents who ride the bus prefer access to more places over frequent bus service, whereas non-riders prefer more frequent transit service. Second, the models suggest that younger generations are more supportive of transit improvements than older age groups. Third, people living near bus routes and those with higher income levels are more willing to pay for proposed transit improvements. The findings of this study should inform transit agencies that are considering or are in the process of redesigning their bus networks.
      Citation: Transportation Research Record
      PubDate: 2021-05-31T06:50:25Z
      DOI: 10.1177/03611981211013043
       
  • Household Evacuation Planning and Preparation for Future Hurricanes: Role
           of Utility Service Disruptions

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      Authors: Nafisa Halim, Fan Jiang, Mohammad Khan, Sisi Meng, Pallab Mozumder
      Abstract: Transportation Research Record, Ahead of Print.
      We analyzed data from a survey administered to 1,212 respondents living in superstorm Hurricane Sandy-affected areas. We estimated the effect of having experienced hurricane-induced disruptions to utility services, such as electricity, water, gas, phone service, and public transportation, on having an evacuation plan. Around 39% of respondents reported having an evacuation plan in case a hurricane affects their neighborhood this year. Respondents who had experienced disruptions to electricity supply had an approximately 11 percentage-point higher likelihood of having an evacuation plan than those who had experienced no such disruptions. Respondents who had experienced monetary losses from Hurricane Sandy had around a five percentage-point higher likelihood of having an evacuation plan compared with those who had not. Among control variables, prior evacuation, distance to the coastline, residence in a flood zone, concern about the impacts of future natural disaster events, had window protection, and household members being disabled, each had an association with residents’ future evacuation planning and hurricane preparedness. In light of these findings, we discuss the policy implications of our findings for improving disaster management in hurricane-prone areas.
      Citation: Transportation Research Record
      PubDate: 2021-05-29T08:16:43Z
      DOI: 10.1177/03611981211014529
       
  • Revisiting Transit-Oriented Development Evaluation for Urban Master Plans
           in the Context of Developing Countries

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      Authors: Minoo Harirchian, Mahya Azadi, Shahab Kermanshahi, Mahdi Bashirinia, Milad Ghasri
      Abstract: Transportation Research Record, Ahead of Print.
      Transit-oriented development (TOD) advocates sustainable development and the building of livable neighborhoods. Several measures are proposed to evaluate TOD principles; however, the suitability of these measures is not fully explored in the context of developing countries. This paper provides a systematic method for multivariate analysis of TOD measures in the context of developing countries. A bivariate analysis is conducted to simultaneously study all TOD measures against the distance to transit measure because of its essential role in TOD. A dynamic zoning system is introduced to capture a realistic reflection of neighborhood that is walkable for its residents. In the proposed zoning system, neighboring zones can overlap, as the walkable areas for the nearby residences may overlap. The adherence of Tehran’s Master Plan to TOD principles is examined with a focus on TOD measures and multidimensionality in assessment. The results highlight the curse and the blessing of the high-density urban sprawl in sustainable development.
      Citation: Transportation Research Record
      PubDate: 2021-05-29T08:16:23Z
      DOI: 10.1177/03611981211014526
       
  • Application of a Tax to E-Commerce Deliveries in Barcelona

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      Authors: Genís Majoral, Francesc Gasparín, Sergi Saurí
      Abstract: Transportation Research Record, Ahead of Print.
      The number of e-commerce transactions is increasing worldwide. Deliveries of goods purchased online generate externalities throughout the whole supply chain and, particularly, the increasing concern about the last-mile distribution of goods. The escalating presence of vans in cities contributes to poor air quality, climate change, noise, and congestion. So far, the majority of solutions to address this issue are based on the supply side, such as electric vans, optimizing the routing and pick-up-points, and so forth. Even in other transport sectors, pricing solutions are well known, yet they have not been extended to e-commerce delivery. This paper aims to propose an environmental tax falling on the demand side and equaling the externalities from this activity. The analysis has been particularized for the case of Barcelona. A cost–benefit analysis to assess the impact of such a tax has been carried out. When revenue collection is reinvested in the logistics sector, and for subsidizing electric distribution vehicles, the results indicate that the levying of the tax can generate positive outcomes.
      Citation: Transportation Research Record
      PubDate: 2021-05-29T08:15:27Z
      DOI: 10.1177/03611981211012412
       
  • Incorporating Flood Hazards into Pavement Sustainability Assessment

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      Authors: Jessica Achebe, Oluremi Oyediji, Rebecca K. Saari, Susan Tighe, Filzah Nasir
      Abstract: Transportation Research Record, Ahead of Print.
      The functional and structural performance of pavement infrastructures are at risk from climate change impacts. However, past sustainability assessment studies do not consider how the performance of infrastructure will be affected by a changing climate. The goal of this research is to investigate the impacts of flooding in a unified assessment of the resilience and sustainability of pavement. A case study of concrete pavement was evaluated for scenarios with and without flooding. The AASHTOWare Pavement ME design program was used to simulate the structural performance of typical jointed plain concrete pavement (JPCP) designs for collector roads in Canada. Predicted performance was used in the resilience and sustainability assessment under scenarios with and without flooding. The damage ratio and cost of damage were assessed to quantify the resilience of concrete pavement to floods. Life cycle costs and environmental impacts were compared across a climate change scenario with consideration of maintenance and rehabilitation activities. Results reveal that a typical Ontario JPCP design with structural slab thickness
      Citation: Transportation Research Record
      PubDate: 2021-05-29T08:15:23Z
      DOI: 10.1177/03611981211014525
       
  • Understanding Fatal Crash Reporting Patterns in Bangladeshi Online Media
           using Text Mining

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      Authors: Subasish Das
      Abstract: Transportation Research Record, Ahead of Print.
      Traffic crashes are a major public health concern. In 2016, traffic crashes resulted in over 1.35 million deaths worldwide. In Bangladesh alone, the number of reported traffic fatalities was 2,376 in 2016. However, the World Health Organization estimated that the true number of traffic fatalities in Bangladesh ranges between 20,730 and 29,177. Editorial traffic crash reports in Bangladesh, and the number of crashes that are reported, vary widely among different media outlets. This study employed a Google News Alert to collect fatal crash reports from online English daily newspapers. The current study compiled a database of 419 fatal crash-related reports over a six-month period (November 2018–April 2019). The reports contain a total of 81,019 words. The results of this study reveal that online news coverage of traffic fatalities tends to vary from news agency to news agency. Furthermore, these reports do not usually cover key contributing factors of crash occurrences; the geometric features of crash occurrence sites are rarely reported. The findings demonstrate the importance of deciphering media coverage to develop potential safety risk measures in Bangladesh. The current findings provide strong support for the need for guidelines to help media outlets adequately document fatal crash reports.
      Citation: Transportation Research Record
      PubDate: 2021-05-29T08:15:14Z
      DOI: 10.1177/03611981211014200
       
  • Analysis of the Integration Usage Patterns of Multiple Shared Mobility
           Modes and Metro System

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      Authors: Hui Bi, Zhirui Ye, Yi Zhang
      Abstract: Transportation Research Record, Ahead of Print.
      Although metro systems are established in many Asian cities including Chengdu, they have yet to cover every corner of a city. Understanding the transfer behavior of passengers can provide insight into achieving efficient and sustainable urban transport systems. Combining shared mobility programs with metro to improve the weaknesses of traditional feeder modes is viewed as the most promising line of business in sustainable transportation for the near future. Therefore, this study aims to comprehend the factors affecting the usage regularity of shared mobility by deepening the knowledge on endogenous and exogenous effects, and integrating two modes, namely bike-sharing and ridesourcing. Two systems are cross-compared, first in respect of their travel characteristics. Then, a binary logistic model is employed to capture the influences of trip characteristics and travel environment characteristics on their usage frequency. Researchers found that trip distance is significantly associated with users’ mode options, indicating that bike-sharing and ridesourcing mainly serve short-distance and long-distance transfer users, respectively, although some users may be confused which feeder mode to choose for the journeys of 2 km to 4 km. There were also meteorological and temporal influences, with the competition and complementation of multiple shared mobility feeder modes being likely to change under extreme weather conditions, during peak hours, or on weekends. Besides, metro-shared mobility users value the accessibility of two kinds of transport service, which is affected by the metro station and its surrounding built environment. This study and the proposed policy implications are helpful for embracing a sustainable mobility design from general optimum.
      Citation: Transportation Research Record
      PubDate: 2021-05-29T08:15:03Z
      DOI: 10.1177/03611981211013351
       
  • Unsaturated Hydraulic Conductivity Variation of Expansive Yazoo Clay with
           Wet-Dry Cycles

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      Authors: John Ivoke, Mohammad Sadik Khan, Masoud Nobahar
      Abstract: Transportation Research Record, Ahead of Print.
      Expansive soils are subjected to shrink-swell behavior with moisture variation in Mississippi, United States. With successive moisture and temperature variations over the seasons, the hydraulic conductivity of expansive soil is subjected to change because of the development of shrinkage cracks, which can be as large as as 1.2 cm wide and 1.5 m deep in the field, affecting the vertical hydraulic conductivity (Kv), whereas the horizontal hydraulic conductivity (Kh) remains fairly constant. The current study intends to investigate the hydraulic conductivity of highly expansive Yazoo clay at different wet-dry cycles. To observe the changes in the hydraulic conductivity with different wet-dry cycles in the laboratory, an instantaneous profile method to measure the permeability was utilized. Compacted Yazoo clay samples at different initial moisture content instrumented with moisture sensors at different depths to monitor changes in the moisture content were investigated. The samples were subjected to one, two, and three numbers (1N, 2N, and 3N) of wetting and drying cycles. For the drying process, testing chambers are kept in a controlled high-temperature booth of about 37°C simulating high summer temperatures in Mississippi. After the end of the wet-dry cycles, the test is performed to investigate the changes in the hydraulic conductivity of soil with the presence of shrinkage cracks. The hydraulic conductivity of highly plastic clay is very low at a fully compacted state and was observed to be (1.0×10-8 cm/s) at the 1N wetting phase. However, with an increment in the wet-dry cycles, the Kv of Yazoo clay increases (3.70×10-4 cm/s) after the sample is exposed to three wet-dry cycles. Even though the changes in the Kv of highly plastic clay define the infiltration behavior, which mostly controls the slope failure and pavement distress, consideration of the climatic loads is ignored in the design phase of the highway embankment and levees. By inclusion of the climatic variation, and evaluating the performance, the design life and resilience of the structures can be significantly increased
      Citation: Transportation Research Record
      PubDate: 2021-05-29T08:14:56Z
      DOI: 10.1177/03611981211011994
       
  • System Dynamics Modeling for a Public–Private Partnership Program to
           Promote Bicycle–Metro Integration Based on Evolutionary Game

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      Authors: Jianming Cai, Yue Liang
      Abstract: Transportation Research Record, Ahead of Print.
      A marriage between dockless bike-sharing systems and rail transit presents new opportunities for sustainable transportation in Chinese cities. However, how to promote the bicycle–metro integration mode remains largely unstudied. This paper designs a public–private partnership program to promote bicycle–metro integration. We consider the cooperation between bike-sharing companies and rail transit companies to improve both services and attract long-distance travelers to choose the bicycle–metro integration mode, with government subsidies. To analyze the proportion of each population participating in this public–private partnership program, we establish an evolutionary game model considering bike-sharing companies, rail transit companies, and long-distance travelers, and obtain eight scenarios of equilibriums and corresponding stable conditions. To prove the evolutionary game analysis, we construct a system dynamics simulation model and confirm that the public–private partnership project can be achieved in reality. We discuss key parameters that affect the final stable state through sensitivity analysis. The results demonstrate that by reasonably adjusting the values of parameters, each equilibrium can be changed into an optimal evolutionary stable strategy. This study can provide useful policy implications and operational recommendations for government agencies, bike-sharing companies, and transit authorities to promote bicycle–metro integration.
      Citation: Transportation Research Record
      PubDate: 2021-05-29T08:13:50Z
      DOI: 10.1177/03611981211012425
       
  • Exploratory Evaluation of a Concept Combining Incentivized On-Demand
           Ridesharing with Congestion Pricing

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      Authors: Patrick DeCorla-Souza
      Abstract: Transportation Research Record, Ahead of Print.
      This paper presents an innovative transportation demand management concept involving congestion pricing synergistically combined with incentivized on-demand ridesharing. An exploratory evaluation of the concept was undertaken using sketch-planning tools developed by the Federal Highway Administration. The analysis suggests that the concept could be financially viable, achieve significant economic benefits, and potentially generate surplus revenues that could be sufficient to address transportation funding gaps.
      Citation: Transportation Research Record
      PubDate: 2021-05-29T08:13:49Z
      DOI: 10.1177/03611981211011651
       
  • Risk to Bicyclists in a Separated Path from Left Turns across Multiple
           Lanes: A Case for Protected-Only Left Turns

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      Authors: Ray Saeidi Razavi, Peter G. Furth
      Abstract: Transportation Research Record, Ahead of Print.
      At signalized intersections, permitted left turns (i.e., on a green ball, after yielding) across multiple through lanes and across a separated bike lane or bike path present a threat to bicyclist safety. A conflict study of two such intersections with a bidirectional bike path found that when cyclists cross while a vehicle is ready to turn left and there is no opposing through traffic to block it, the chance of the left-turning motorist yielding safely was only 9%, and the chance of their yielding at all—including yielding only after beginning the turn, then stopping in the opposing through lanes—was still only 37%. Motorist non-yielding rates were worse toward bikes arriving during green, toward bikes approaching from the opposite direction (i.e., riding on the right side of the road), and toward bikes facing a queue with multiple left turning vehicles. Of 112 cyclists who arrived on green when there was at least one left-turning car, but no opposing through traffic blocking it, 73 had to slow or stop to avoid a collision. Although these conflicts could be essentially eliminated using protected-only left turn phasing (turn on green arrow), common existing criteria prefer permitted left turns to reduce vehicular delay. A case study shows how, by considering multiple signalization alternatives, it can be possible to convert left turns to protected-only phasing without imposing a substantial delay burden on vehicles or other road users.
      Citation: Transportation Research Record
      PubDate: 2021-05-29T08:13:29Z
      DOI: 10.1177/03611981211010789
       
  • Survey of Work Zone Practices and Validation of Highway Capacity Manual
           Work Zone Capacity Model

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      Authors: Raju Thapa, Julius Codjoe, Amanua Osafo
      Abstract: Transportation Research Record, Ahead of Print.
      Capacity at work zones is one of the major factors affecting queueing at work zones. Different states within the United States use their own methodology in determining work zone capacities and when to implement lane closures at work zones. The objective of this study was two-fold: first, to provide a synthesis of work zone lane closure procedures practiced by the various Departments of Transportation (DOTs) nationwide; and secondly, to validate the Highway Capacity Manual 6th edition’s (HCM 6) work zone capacity model using field-collected data in the state of Louisiana. The first objective was met by administering a survey to DOTs nationwide. The survey revealed that half of the states that responded to the survey require minimum capacity for short-term work zone lane closures, with minimum capacity ranging from 1100 to 1900 passenger cars per hour per lane. In addition, most of the states reported implementing consistent policies across various district offices. The survey findings provide a good source of information on queue analysis and work zone lane closure policies adopted across different DOTs. The second objective was met by collecting traffic flow data from 10 work zone sites within the state of Louisiana and validating the capacity model in the HCM 6. Results showed the HCM 6 model slightly overestimating the average field-observed capacity by 6%. In the absence of local data, the HCM 6 model provides a great tool to estimate work zone capacities in Louisiana.
      Citation: Transportation Research Record
      PubDate: 2021-05-28T09:00:05Z
      DOI: 10.1177/03611981211014524
       
  • Evaluation of the Effect of Aircraft Tire Inflation Pressure on Thin
           Asphalt Pavements

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      Authors: W. Jeremy Robinson
      Abstract: Transportation Research Record, Ahead of Print.
      Sixteen nonstandard asphalt pavement test items were subjected to accelerated traffic testing to determine whether reductions in aircraft tire inflation pressure had a meaningful effect on pavement performance. Materials evaluated included a strong and weak base course (limestone and gravel), three asphalt thicknesses (2.5 cm, 3.8 cm, and 6.3 cm), and two aircraft types (C-130 and C-17). Each single-wheel aircraft tire was operated at two tire inflation pressures, that is, normal operating pressure and approximately 20% below normal, while maintaining total wheel load. Rutting behavior and surface cracking were the primary measured distress mechanisms and were used to evaluate pavement performance. It was found that reducing tire inflation pressure on the weak base course materials had little effect on rutting performance, suggesting that total load rather than tire pressure dominated performance. Conversely, tire pressure reductions on strong base course materials provided an improvement in rutting performance ranging from 15% to 73%. Improvement in surface cracking was observed in some cases with a reduction in tire inflation pressure; however, a meaningful amount of surface cracking was not observed in most test items until near or after 25.4 mm of rutting. Thus, it can be concluded that the primary mode of failure was pavement rutting rather than extensive fatigue cracking. Overall, it was found that a reduction in tire pressure on competent aggregate base improved pavement performance, which could permit increased aircraft operations on thin flexible airfield pavements.
      Citation: Transportation Research Record
      PubDate: 2021-05-27T08:39:18Z
      DOI: 10.1177/03611981211014527
       
  • Capacitated Location-Allocation-Routing Problem with Time Windows for
           On-Demand 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) operation has gained traction with the advancements in distributed electric propulsion and the emergence of electric vertical take-off and landing aircraft. Start-up companies and aircraft manufacturers are pursuing the possibility of operating UAT at scale in urban and suburban areas and at an affordable price. However, considerable uncertainties remain about several strategic, tactical, and operational aspects that affect UAT adoption. We envision a mature state of UAT operation in which the UAT operator offers door-to-door, multimodal, on-demand, and per-seat service. We propose the concept of flexible meeting points for UAT operation where passengers are flexible about the location of the UAT pads for boarding and deboarding, and could therefore be pooled together to share an aircraft. Consequently, we model UAT fleet operation as a capacitated location-allocation-routing problem with time windows and present a mixed integer programming formulation. The formulation addresses decisions on request acceptance and rejection, allocation of requests to flights, and aircraft routing and scheduling. Additionally, it allows for consolidating the demand to increase the aircraft’s utilization and service rate. The numerical results indicate that the demand consolidation scheme could significantly decrease the number of rejected requests and the aerial mileage. Depending on the operator’s business model, the proposed formulation could be used offline in a static and deterministic setting when all requests are known in advance, or it could be employed online by sequentially solving the static and deterministic snapshot problems with no knowledge about future requests.
      Citation: Transportation Research Record
      PubDate: 2021-05-27T08:39:07Z
      DOI: 10.1177/03611981211014892
       
  • Cordon-Based Pricing Schemes for Mixed Urban-Freeway Networks using
           Macroscopic Fundamental Diagrams

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      Authors: Xuting Wang, Vikash V. Gayah
      Abstract: Transportation Research Record, Ahead of Print.
      The development of traffic models based on macroscopic fundamental diagrams (MFD) enables many real-time control strategies for urban networks, including cordon-based pricing schemes. However, most existing MFD-based pricing strategies are designed only to optimize the traffic-related performance, without considering the revenue collected by operators. In this study, we investigate cordon-based pricing schemes for mixed networks with urban networks and freeways. In this system, heterogeneous commuters choose their routes based on the user equilibrium principle. There are two types of operational objective for operating urban networks: (1) to optimize the urban network’s performance, that is, to maximize the outflux; and (2) to maximize the revenue for operators. To compare those two objectives, we first apply feedback control to design pricing schemes to optimize the urban network’s performance. Then, we formulate an optimal control problem to obtain the revenue-maximization pricing scheme. With numerical examples, we illustrate the difference between those pricing schemes.
      Citation: Transportation Research Record
      PubDate: 2021-05-26T10:44:56Z
      DOI: 10.1177/03611981211015991
       
  • Implementation Sequence Optimization for Dedicated Bus Lane Projects

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      Authors: Murat Bayrak, S. Ilgin Guler, Paul Schonfeld
      Abstract: Transportation Research Record, Ahead of Print.
      Transportation projects are often implemented in phases, and the total project duration can span years. Optimization of the sequence in which transportation projects are implemented can decrease the severity of disruptions caused by construction, reduce the total cost of projects, and increase the present value of the benefits of the project. This paper presents a method for optimizing the sequence and location of dedicated bus lane implementations. The proposed method is based on a bi-level optimization framework. The lower level simulates the traffic using a link transmission model to evaluate car and bus delays, while the upper level optimizes the locations of bus lanes and/or the implementation sequence of a given bus lane configuration. If the budget or other resource constraints are binding, the optimized sequence uniquely determines the optimal schedule. The solution method is evaluated for a test network, and an analysis of sensitivity to different demand patterns and different bus lane configurations is conducted. First, the optimized locations for bus lane implementation are determined for an illustrative test network. Results suggest that, when considering the implementation sequence for the optimized set of bus lane locations, the sequence of implementation does not yield significant benefits. However, if bus lanes are implemented on every possible link, the results suggest that prioritizing the implementation of bus lanes on peripheral links would reduce the total cost the most. These locations coincide with the set of optimized locations for bus lane implementation. Further tests considering non-uniform demand patterns also confirm these findings.
      Citation: Transportation Research Record
      PubDate: 2021-05-26T08:35:27Z
      DOI: 10.1177/03611981211014889
       
  • Case Study of Social Sustainability Practices in U.S. Small Hub Airports

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      Authors: Caroline K. Marete, Mary E. Johnson
      Abstract: Transportation Research Record, Ahead of Print.
      Airports have economic, environmental, and social impacts on communities. Many of these impacts are influenced by airport management decisions. Airport sustainability may be thought of as having four primary areas: environmental, economic, operational, and social. The objective of this study is to understand better the adoption of social sustainability practices in small hub airport planning in the United States. The small hub airports in this study participated in the Federal Aviation Administration Airport Improvement Program for sustainability planning and have published their sustainability plans as either standalone sustainability management plans or integrated sustainable master plans. Plans from the six airports were gathered and examined as part of an exploratory case study analysis. The findings show that small hub airports do not use the same framework or select the same practices for social sustainability. Social sustainability practices for these six small hub airports focus on four stakeholder categories: passengers and travelers, employees, communities and local businesses, and concessionaires and tenants.
      Citation: Transportation Research Record
      PubDate: 2021-05-26T08:34:23Z
      DOI: 10.1177/03611981211014209
       
  • Path-Based Dynamic Vehicle Dispatch Strategy for Demand Responsive Transit
           Systems

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      Authors: Shiyu Shen, Yanfeng Ouyang, Shuai Ren, Luyun Zhao
      Abstract: Transportation Research Record, Ahead of Print.
      Demand responsive transit (DRT) has the potential to provide passengers with higher accessibility and lower travel time as compared with conventional transit, and at the same time make more efficient use of vehicle capacity than traditional taxi. In many current systems, vehicles are assigned to passengers along travel paths that are chosen myopically. When information on future demand distribution is available, it would be more beneficial to dispatch transit vehicles strategically to areas with a higher probability of generating passengers. This paper proposes a mathematical model for a dynamic DRT vehicle dispatch problem. It determines in real time how the operating vehicles shall be used to serve arriving passenger demand, and which paths the vehicles should choose to achieve a balance between operator and passenger costs. The model is solved by an approximate dynamic programming (ADP) based solution approach. Case studies, including a hypothetical numerical example and a real-world case in Qingdao, China, have been conducted to demonstrate the applicability of the proposed modeling framework. Results show that the proposed ADP solution can significantly improve the overall system performance as compared with myopic benchmarks.
      Citation: Transportation Research Record
      PubDate: 2021-05-26T08:34:04Z
      DOI: 10.1177/03611981211014205
       
  • Eco-Drive Technology, Human Factors, and Environmental and Economic
           Benefits

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      Authors: Ata M. Khan, Greg Kent, Omar Choudhry
      Abstract: Transportation Research Record, Ahead of Print.
      The objective of eco-drive technology is to reduce fuel consumption and resulting emissions using advances in communication and traffic control technologies with capability to support infrastructure-to-vehicle connection in a signalized network. On the human factors side, there is growing interest across the world in advising drivers to take eco-drive actions by effectively using the green phase of the signal cycle time to save fuel and reduce emissions. This paper describes a large-scale real-world research project in Ottawa (Ontario, Canada) on this subject. The technology and methods that support the green light optimized speed advisory (GLOSA) system were refined and all 1,178 traffic signals in the city were equipped to connect with a fleet of vehicles. Field study data were analyzed for speed trajectories, fuel consumption, and GLOSA compliance. Greenhouse emissions and fuel cost changes were computed. An anonymous questionnaire study investigated driver perception of the usefulness of the signal data displayed on an in-vehicle unit as advice on driving adjustment decisions made under prevailing traffic conditions. The over 65% compliance with GLOSA and the results of the driver questionnaire were mutually consistent. The fuel saving amounted to 7.6% but was adjusted to 5% because of uncertainties in daily vehicle travel. The reduction in carbon dioxide equivalent and fuel cost reported in the paper are based on a 5% adjustment. These results can be used for cost–benefit studies. Also, simulation-based research projects can verify their findings with the real-world experience reported in this paper.
      Citation: Transportation Research Record
      PubDate: 2021-05-26T08:33:45Z
      DOI: 10.1177/03611981211014204
       
  • Identification of Potential Freight Parking Locations in Urban Areas

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      Authors: Glenn Vorhes, Ernest Perry, Soyoung Ahn
      Abstract: Transportation Research Record, Ahead of Print.
      Truck parking is a crucial element of the United States’ transportation system as it provides truckers with safe places to rest and stage for deliveries. Demand for truck parking spaces exceeds supply and shortages are especially common in and around urban areas. Freight operations are negatively affected as truck drivers are unable to park in logistically ideal locations. Drivers may resort to unsafe practices such as parking on ramps or in abandoned lots. This report seeks to examine the potential parking availability of vacant urban parcels by establishing a methodology to identify parcels and examining whether the identified parcels are suitable for truck parking. Previous research has demonstrated that affordable, accessible parcels are available to accommodate truck parking. When used in conjunction with other policies, adaptation of urban sites could help reduce the severity of truck parking shortages. Geographic information system parcel and roadway data were obtained for one urban area in each of the 10 Mid America Association of Transportation Officials region states. Area and proximity filters were applied followed by spectral analysis of satellite imagery to identify candidate parcels for truck parking facilities within urban areas. The automated processes created a ranked short list of potential parcels from which those best suited for truck parking could be efficiently identified for inspection by satellite imagery. This process resulted in a manageable number of parcels to be evaluated further by local knowledge metrics such as availability and cost, existing infrastructure and municipal connections, and safety.
      Citation: Transportation Research Record
      PubDate: 2021-05-26T08:33:02Z
      DOI: 10.1177/03611981211013027
       
  • Improving Interstate Freeway Travel Time Reliability Analysis by
           Clustering Travel Time Distributions

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      Authors: Xiaoxiao Zhang, Mo Zhao, Justice Appiah, Michael D. Fontaine
      Abstract: Transportation Research Record, Ahead of Print.
      Travel time reliability quantifies variability in travel times and has become a critical aspect for evaluating transportation network performance. The empirical travel time cumulative distribution function (CDF) has been used as a tool to preserve inherent information on the variability and distribution of travel times. With advances in data collection technology, probe vehicle data has been frequently used to measure highway system performance. One challenge with using CDFs when handling large amounts of probe vehicle data is deciding how many different CDFs are necessary to fully characterize experienced travel times. This paper explores statistical methods for clustering CDFs of travel times at segment level into an optimal number of homogeneous clusters that retain all relevant distributional information. Two clustering methods were tested, one based on classic hierarchical clustering and the other used model-based functional data clustering, to find out their performance on clustering distributions using travel time data from Interstate 64 in Virginia. Freeway segments and those within interchange areas were clustered separately. To find the proper data format as clustering input, both scaled and original travel times were considered. In addition, a non-data-driven method based on geometric features was included for comparison. The results showed that for freeway segments, clustering using travel times and the Anderson–Darling dissimilarity matrix and Ward’s linkage had the best performance. For interchange segments, model-based clustering provided the best clusters. By clustering segments into homogenous groups, the results of this study could improve the efficiency of further travel time reliability modeling.
      Citation: Transportation Research Record
      PubDate: 2021-05-26T08:32:43Z
      DOI: 10.1177/03611981211012002
       
  • Relationship between Rheological Indices and Cracking Performance of
           Virgin, Recycled, and Rejuvenated Asphalt Binders and Mixtures

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      Authors: Fawaz Kaseer, Amy Epps Martin, Edith Arámbula-Mercado
      Abstract: Transportation Research Record, Ahead of Print.
      Long-term cracking performance of asphalt mixtures is heavily influenced by asphalt binder rheology, and changes in binder stiffness, ductility, and aging condition significantly affect the cracking resistance of the corresponding asphalt mixture. This study evaluated the effectiveness of several common and recently developed binder rheological indices in capturing the effects of binder performance grade (PG) and source, recycled binder content, recycling agent (rejuvenator) dose, and long-term aging. These binder rheological indices included the Superpave intermediate-temperature PG (PGI), the Glover-Rowe (G-R) parameter, the crossover temperature (Tδ = 45°), the rheological index (R-value), and ΔTc. This study also directly compared the binder rheological indices with the cracking performance of corresponding asphalt mixtures to explore possible correlations and their robustness. Asphalt mixture cracking performance was evaluated using the Illinois Flexibility Index Test (I-FIT) for intermediate-temperature cracking, and the disk-shaped compact tension (DCT) test and the uniaxial thermal stress and strain test (UTSST) for low-temperature cracking.Results indicated that all the binder rheological indices (except PGI) consistently captured the effects of binder blend composition and proportions and aging condition, with a few exceptions. Results also showed that the G-R parameter, the crossover temperature (Tδ = 45°), and ΔTc had the best correlation to asphalt mixture and field core cracking performance as compared with other rheological indices (PGI and R-value), with ΔTc demonstrating the overall best correlation to mixture cracking performance.
      Citation: Transportation Research Record
      PubDate: 2021-05-26T08:27:28Z
      DOI: 10.1177/03611981211007479
       
  • Effects of Connectivity and Traffic Observability on an Adaptive Traffic
           Signal Control System

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      Authors: S M A Bin Al Islam, Mehrdad Tajalli, Rasool Mohebifard, Ali Hajbabaie
      Abstract: Transportation Research Record, Ahead of Print.
      The effectiveness of adaptive signal control strategies depends on the level of traffic observability, which is defined as the ability of a signal controller to estimate traffic state from connected vehicle (CV), loop detector data, or both. This paper aims to quantify the effects of traffic observability on network-level performance, traffic progression, and travel time reliability, and to quantify those effects for vehicle classes and major and minor directions in an arterial corridor. Specifically, we incorporated loop detector and CV data into an adaptive signal controller and measured several mobility- and event-based performance metrics under different degrees of traffic observability (i.e., detector-only, CV-only, and CV and loop detector data) with various CV market penetration rates. A real-world arterial street of 10 intersections in Seattle, Washington was simulated in Vissim under peak hour traffic demand level with transit vehicles. The results showed that a 40% CV market share was required for the adaptive signal controller using only CV data to outperform signal control with only loop detector data. At the same market penetration rate, signal control with CV-only data resulted in the same traffic performance, progression quality, and travel time reliability as the signal control with CV and loop detector data. Therefore, the inclusion of loop detector data did not further improve traffic operations when the CV market share reached 40%. Integrating 10% of CV data with loop detector data in the adaptive signal control improved traffic performance and travel time reliability.
      Citation: Transportation Research Record
      PubDate: 2021-05-24T09:22:07Z
      DOI: 10.1177/03611981211013036
       
  • Non-Destructive Detection of Asphalt Concrete Stripping Damage using
           Ground Penetrating Radar

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      Authors: Ye Ma, Mostafa A. Elseifi, Nirmal Dhakal, Mohammad Z. Bashar, Zhongjie Zhang
      Abstract: Transportation Research Record, Ahead of Print.
      Ground penetrating radar (GPR) is a non-destructive evaluation technique, which has been applied to assess as-built pavement conditions and to evaluate damage and deterioration that develop over time. The objective of this study was to develop a methodology that uses GPR to detect moisture-related stripping damage in asphalt pavements. To achieve this objective, A Finite-Difference Time-Domain based simulation program was used to study the propagation of GPR signals in a stripped pavement. Field test data including GPR scans and visual inspection of cores of 202 pavement sections were used to study the relationship between GPR traces and asphalt concrete (AC) stripping damage. Based on this analysis, a novel GPR-based indicator, known as the accumulating in-layer peaks (AIP), was introduced to detect stripping damage in asphalt pavements. Field data and pavement cores were used to validate the proposed indicator and to evaluate its effectiveness in detecting the presence, extent, and severity of stripping in in-service pavement sections. Based on the results of the study, it was found that the presence of a void in the middle of the AC layer resulted in positive peaks in the reflected waves as indicated by the simulation of GPR signals. In addition, detected intermediate wave peaks between the surface and the interface between the AC and base layers on the GPR traces were associated with stripping damage in the AC layer. The AIP predicted accuracies for stripped and non-stripped sections were 80% and 96%, respectively, indicating its effectiveness in detecting stripping damage in flexible pavements.
      Citation: Transportation Research Record
      PubDate: 2021-05-22T01:57:20Z
      DOI: 10.1177/03611981211014199
       
  • Using Traffic Disturbance Metrics to Estimate and Predict Freeway Traffic
           Breakdown and Safety Events

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      Authors: Leila Azizi, Mohammed Hadi
      Abstract: Transportation Research Record, Ahead of Print.
      The introduction of connected vehicles, connected and automated vehicles, and advanced infrastructure sensors will allow the collection of microscopic metrics that can be used for better estimation and prediction of traffic performance. This study examines the use of disturbance metrics in combination with the macroscopic metrics usually used for the estimation of traffic safety and mobility. The disturbance metrics used are the number of oscillations and a measure of disturbance durations in the time exposed time to collision. The study investigates using the disturbance metrics in data clustering for better off-line categorization of traffic states. In addition, the study uses machine-learning based classifiers for the recognition and prediction of the traffic state and safety in real-time operations. The study also demonstrates that the disturbance metrics investigated are significantly related to crashes. Thus, this study recommends the use of these metrics as part of decision tools that support the activation of transportation management strategies to reduce the probability of traffic breakdown, ease traffic disturbances, and reduce the probability of crashes.
      Citation: Transportation Research Record
      PubDate: 2021-05-22T01:56:02Z
      DOI: 10.1177/03611981211012422
       
  • Estimating Express Train Preference of Urban Railway Passengers Based on
           Extreme Gradient Boosting (XGBoost) using Smart Card Data

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      Authors: Eun Hak Lee, Kyoungtae Kim, Seung-Young Kho, Dong-Kyu Kim, Shin-Hyung Cho
      Abstract: Transportation Research Record, Ahead of Print.
      As the share of public transport increases, the express strategy of the urban railway is regarded as one of the solutions that allow the public transportation system to operate efficiently. It is crucial to express the urban railway’s express strategy to balance a passenger load between the two types of trains, that is, local and express trains. This research aims to estimate passengers’ preference between local and express trains based on a machine learning technique. Extreme gradient boosting (XGBoost) is trained to model express train preference using smart card and train log data. The passengers are categorized into four types according to their preference for the local and express trains. The smart card data and train log data of Metro Line 9 in Seoul are combined to generate the individual trip chain alternatives for each passenger. With the dataset, the train preference is estimated by XGBoost, and Shapley additive explanations (SHAP) is used to interpret and analyze the importance of individual features. The overall F1 score of the model is estimated to be 0.982. The results of feature analysis show that the total travel time of the local train feature is found to substantially affect the probability of express train preference with a 1.871 SHAP value. As a result, the probability of the express train preference increases with longer total travel time, shorter in-vehicle time, shorter waiting time, and few transfers on the passenger’s route. The model shows notable performance in accuracy and provided an understanding of the estimation results.
      Citation: Transportation Research Record
      PubDate: 2021-05-22T01:54:55Z
      DOI: 10.1177/03611981211013349
       
  • Assessing Climate Change Impact on Asphalt Binder Grade Selection and its
           Implications

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      Authors: Surya T. Swarna, Kamal Hossain, Harshdutta Pandya, Yusuf A. Mehta
      Abstract: Transportation Research Record, Ahead of Print.
      Anthropogenic climate change is having and will continue to have unpredictable effects on Canadian weather. Trends in average annual temperatures have been rapidly increasing over the last 50 years. The severe climatic variations in Canada are in line with global changes in climate occurring as a result of increased greenhouse gas concentrations in the atmosphere. Under the current CO2 emission scenarios, scientists predict the climate trends to further intensify in the near future. It is well known that asphalt binder is highly sensitive to climate factors. For this reason, reviewing asphalt binder grade is a vital step, and can help decelerate pavement deterioration. The objective of this study was to assess the change in asphalt binder grade for the future climate and to determine the influence of change in binder grade on the performance of pavements in Canada. To achieve this, the analysis was carried out in five phases. In the first phase, statistically downscaled climate change models were gathered from the Pacific Climate Impacts Consortium database. In the second phase, the temperature and precipitation data were extracted for the selected locations in southern Canada. In the third phase, the asphalt binder grade was determined for future climate data. In the fourth phase, the pavement materials, traffic, and structural data were collected from the Long-Term Pavement Performance database. Lastly, the pavement performance with the base binder and the upgraded binder were assessed using AASHTOware Mechanistic–Empirical Pavement Design. The results reemphasize the necessity of upgrading the asphalt binder grade in various provinces of Canada.
      Citation: Transportation Research Record
      PubDate: 2021-05-22T01:53:31Z
      DOI: 10.1177/03611981211013026
       
  • Effects of Occupational Drivers’ Traffic Accident History on Risk
           Perception, Work Attitudes, and Unstable Driving

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      Authors: Eun Kyoung Chung, So Young Park, Young Woo Sohn
      Abstract: Transportation Research Record, Ahead of Print.
      In previous studies the risk perception of future accidents was the main variable likely to affect safe driving. However, findings on the relationship between traffic accident history and risk perception of future accidents have been inconsistent. Moreover, in the case of occupational drivers, work attitudes could be the main factor affecting safe driving. However, no research has been conducted on the direct relationship between traffic accident history and work attitudes. Therefore, present study examined the effect of occupational drivers’ traffic accident history on their risk perception, work attitudes, and unstable driving. Data analysis was based on a self-reported survey of Korean occupational drivers (n = 388) and their official traffic accident records. Results show that traffic accident history was associated significantly with professional pride, job satisfaction, and aggressive driving but not with risk perception of future accidents or job stress. Moreover, all variables measuring unstable driving behavior were significantly related to professional pride, job satisfaction, and job stress. Furthermore, professional pride turned out to mediate the relationship between traffic accident history and current unstable driving. The major finding is that there is no significant relationship between traffic accident history and risk perception of future accidents. Furthermore, traffic accident history has a significant effect on positive variables such as professional pride and job satisfaction but not on negative variables such as job stress. In addition, the significant mediator in the relationship between traffic accident history and current unstable driving behavior was only professional pride.
      Citation: Transportation Research Record
      PubDate: 2021-05-22T01:51:47Z
      DOI: 10.1177/03611981211012695
       
  • Machine Learning Solutions for Bridge Scour Forecast Based on Monitoring
           Data

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      Authors: Negin Yousefpour, Steve Downie, Steve Walker, Nathan Perkins, Hristo Dikanski
      Abstract: Transportation Research Record, Ahead of Print.
      Bridge scour is a challenge throughout the U.S.A. and other countries. Despite the scale of the issue, there is still a substantial lack of robust methods for scour prediction to support reliable, risk-based management and decision making. Throughout the past decade, the use of real-time scour monitoring systems has gained increasing interest among state departments of transportation across the U.S.A. This paper introduces three distinct methodologies for scour prediction using advanced artificial intelligence (AI)/machine learning (ML) techniques based on real-time scour monitoring data. Scour monitoring data included the riverbed and river stage elevation time series at bridge piers gathered from various sources. Deep learning algorithms showed promising in prediction of bed elevation and water level variations as early as a week in advance. Ensemble neural networks proved successful in the predicting the maximum upcoming scour depth, using the observed sensor data at the onset of a scour episode, and based on bridge pier, flow and riverbed characteristics. In addition, two of the common empirical scour models were calibrated based on the observed sensor data using the Bayesian inference method, showing significant improvement in prediction accuracy. Overall, this paper introduces a novel approach for scour risk management by integrating emerging AI/ML algorithms with real-time monitoring systems for early scour forecast.
      Citation: Transportation Research Record
      PubDate: 2021-05-22T01:50:49Z
      DOI: 10.1177/03611981211012693
       
  • Assessing Physical Activity Achievement by using Transit

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      Authors: Judith Mageau-Béland, Catherine Morency
      Abstract: Transportation Research Record, Ahead of Print.
      Sedentary lifestyle is an important public health issue. To prevent this problem, major health organizations promote the inclusion of physical activity in daily life. Active modes are therefore a well-known way of achieving the health recommendations but walking to transit has also been studied recently. The goal of this study is to assess the level of physical activity achieved by using transit, to verify its contribution in reaching the recommendations. The paper aims to assess the energy expenditure associated with transit use by analyzing the related Metabolic Equivalent of Task. This allows us to express trips as physical activity expenditures and to integrate them in the daily pool of physical activities. For this study, only the main variables affecting the intensity of physical activity are considered. These are the walking time and slope encountered during the walking portion of transit trips. This estimation allows us to estimate the level of physical activity reached by transit users and assess the potential physical activity drivers could achieve if they switched to transit. Finally, the method is also applied to a current transportation issue in Montreal. Results show that transit users living in the Montreal area can achieve 54% of their recommended daily physical activity just by using transit. Current users of motorized modes, if they were to change to transit for their daily travels, could achieve 85% of the recommended daily physical activity.
      Citation: Transportation Research Record
      PubDate: 2021-05-21T01:41:21Z
      DOI: 10.1177/0361198121999057
       
  • Performance Evaluation of Stabilized Base Course using Asphalt Emulsion
           and Asphaltenes Derived from Alberta Oil Sands

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      Authors: Farshad Kamran, Manjunath Basavarajappa, Nura Bala, Leila Hashemian
      Abstract: Transportation Research Record, Ahead of Print.
      Stabilization of the pavement base course using asphalt emulsion is one of the strategies that improves the layer’s strength and, consequently, enhances the pavement performance. In this study, to improve the performance of the asphalt-emulsion-stabilized base course, asphaltenes derived from Alberta oil sands bitumen are added to the mix. Asphaltenes are a byproduct of the deasphalting process of oil sand bitumen and have no significant value in the asphalt industry. The modified mixes are prepared by adding different amounts of asphaltenes in powder form to the mix at ambient temperatures. Marshall stability and indirect tensile strength of the mixtures are evaluated using different contents of asphalt emulsion and asphaltenes. The low-temperature performance properties of the selected mixtures are investigated using an indirect tensile test and for the high-temperature properties a wheel-tracking test is conducted. The results of this study indicate that the addition of asphaltenes to the emulsion-stabilized mix significantly improves rutting resistance, with a slight increase in moisture sensitivity. However, the indirect tensile test results also reveal that modified mixes are slightly more prone to low-temperature cracking than are unmodified ones.
      Citation: Transportation Research Record
      PubDate: 2021-05-20T02:02:30Z
      DOI: 10.1177/03611981211012692
       
  • Topological-Based Measures with Flow Attributes to Identify Critical Links
           in a Transportation Network

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      Authors: Hana Takhtfiroozeh, Mihalis Golias, Sabyasachee Mishra
      Abstract: Transportation Research Record, Ahead of Print.
      An important part of transportation network vulnerability analysis is identifying critical links where failure may lead to severe consequences, and the potential of such incidents cannot be considered negligible. Existing transportation network vulnerability assessment can be categorized as topological, or traffic based. Topological-based assessment identifies the most critical components in the network by considering network structure and connectivity. Traffic-based assessment identifies the most critical components in the network by full-scan analysis and takes into consideration effects of link failures to traffic flow assignment. The former approach does not consider traffic flow dynamics and fails to capture the non-linearity performance function of transport systems while the latter, even though accurate and robust, requires significant computational power and time and may not always be feasible for real life size networks. The primary objective of this paper is to propose new link criticality measures and evaluate their accuracy for transportation network vulnerability assessment. These measures combine characteristics of traffic equilibrium and network topology to balance accuracy and computational complexity. Nine measures are proposed, and their accuracy is compared with three existing traffic-based measures using three case study transportation networks from the literature. Results indicate that three of the proposed measures show strong correlation to the three traffic-based measures while requiring significantly less computational power and time.
      Citation: Transportation Research Record
      PubDate: 2021-05-20T02:00:08Z
      DOI: 10.1177/03611981211013039
       
  • Secondary Crash Identification using Crowdsourced Waze User Reports

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      Authors: Zhihua Zhang, Yuandong Liu, Lee D. Han, Phillip Bradley Freeze
      Abstract: Transportation Research Record, Ahead of Print.
      Secondary crashes are crashes that occur as a result of the nonrecurrent congestion originating from primary crashes, and always have a greater impact on safety and traffic than a single crash. A better understanding of secondary crashes would benefit traffic incident management, and this requires accurate identification of secondary crashes. This study explores using crowdsourced Waze user reports to identify secondary crashes. A network-based clustering algorithm is proposed to extract the primary crash cluster, including all user reports originating from the primary crash, and any crash that occurred within the cluster would be a secondary crash. This method works as a filter to select accurate primary–secondary relationships, thus precisely identifying secondary crashes. A case study is performed with crashes occurring from June to December 2019 on a 30-mi stretch of I-40 in Knoxville, TN. A static threshold method (crash duration and 10 mi) was used to preselect the potential primary–secondary crash pairs, and 75 out of 708 crashes were identified as potential secondary crashes. Based on the preselected primary–secondary crash pairs, 17 secondary crashes were obtained with the proposed method and the results were compared with one of the commonly used methods, the speed contour plot method. Though the proposed method captured fewer secondary crashes, it did identify several secondary crashes that could not be observed with the speed contour plot method. The results showed the applicability of the method and the potential of crowdsourced Waze user reports in secondary crash identification.
      Citation: Transportation Research Record
      PubDate: 2021-05-20T01:55:42Z
      DOI: 10.1177/03611981211013040
       
  • Impact of Non-Aeronautical Revenues on Airport Landing Charge in Global
           Airports

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      Authors: Taejin Shin, Taewoo Roh
      Abstract: Transportation Research Record, Ahead of Print.
      The airport industry, which is heavily regulated, has shown interest in improving performance by increasing non-aeronautical revenues (NAR) to cope with changes in the aviation environment, including trends toward liberalization and privatization. This study uses panel data from three separate years (2012, 2014, and 2016) to analyze how a high NAR share might affect airport charging policies and explores the impact of NAR on landing charges of global airports grouped by type of aircraft. The data was collected from 137 airports worldwide, and generalized least squares regression was performed by including data obtained from the ATRS (Air Transport Research Society) Global Airport Benchmarking Reports. The results indicate that an increase in the NAR share has a statistically significant negative effect on airport charges. This study provides meaningful implications from an empirical analysis of how a change in an airport’s business model, such as increasing the NAR share, might affect airport charges. This study’s results are expected to encourage international airports to be more active in promoting commercial activities (e.g., duty-free shops) and pursue a pricing policy that can bring them a competitive advantage.
      Citation: Transportation Research Record
      PubDate: 2021-05-20T01:54:58Z
      DOI: 10.1177/03611981211012423
       
  • Enhancing the Accuracy of Peak Hourly Demand in Bike-Sharing Systems using
           a Graph Convolutional Network with Public Transit Usage Data

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      Authors: Jung-Hoon Cho, Seung Woo Ham, Dong-Kyu Kim
      Abstract: Transportation Research Record, Ahead of Print.
      With the growth of the bike-sharing system, the problem of demand forecasting has become important to the bike-sharing system. This study aims to develop a novel prediction model that enhances the accuracy of the peak hourly demand. A spatiotemporal graph convolutional network (STGCN) is constructed to consider both the spatial and temporal features. One of the model’s essential steps is determining the main component of the adjacency matrix and the node feature matrix. To achieve this, 131 days of data from the bike-sharing system in Seoul are used and experiments conducted on the models with various adjacency matrices and node feature matrices, including public transit usage. The results indicate that the STGCN models reflecting the previous demand pattern to the adjacency matrix show outstanding performance in predicting demand compared with the other models. The results also show that the model that includes bus boarding and alighting records is more accurate than the model that contains subway records, inferring that buses have a greater connection to bike-sharing than the subway. The proposed STGCN with public transit data contributes to the alleviation of unmet demand by enhancing the accuracy in predicting peak demand.
      Citation: Transportation Research Record
      PubDate: 2021-05-17T12:13:16Z
      DOI: 10.1177/03611981211012003
       
  • Kalman Filtering Method for Real-Time Queue Length Estimation in a
           Connected Vehicle Environment

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      Authors: Yi Wang, Zhihong Yao, Yang Cheng, Yangsheng Jiang, Bin Ran
      Abstract: Transportation Research Record, Ahead of Print.
      Queue length estimation is of great importance for measuring traffic signal performance and optimizing traffic signal timing plans. With the development of connected vehicle (CV) technology, using mobile CV data instead of fixed detector data to estimate queue length has become an important research topic. This study focuses on real-time queue length estimation for an isolated intersection with CV data. A Kalman filtering method is proposed to estimate the queue length in real time using traffic signal timing and real-time traffic flow parameters (i.e., saturated flow rate, traffic volume, and penetration rate), which are estimated using CV trajectories data. A simulation intersection was built and calibrated using field data to evaluate the performance of the proposed method and the benchmark method. Results show that when the CV penetration rate is at 30%, the average values of mean absolute errors, mean absolute percentage errors, and root mean square errors are just 1.6 vehicles, 20.9%, and 2.5 vehicles, respectively. The performance of the proposed model is also better than the benchmark method when the penetration rate of CVs is higher than 20%, which proves the validity of the proposed method. Furthermore, sensitivity analysis indicates that the proposed method requires a high penetration rate of at least 30%.
      Citation: Transportation Research Record
      PubDate: 2021-05-17T12:12:00Z
      DOI: 10.1177/03611981211011996
       
  • Simulation of the Impacts of a Zero-Emission Zone on Freight Delivery
           Patterns in Rotterdam

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      Authors: Michiel de Bok, Lóránt Tavasszy, Ioanna Kourounioti, Sebastiaan Thoen, Larissa Eggers, Victor Mayland Nielsen, Jos Streng
      Abstract: Transportation Research Record, Ahead of Print.
      As part of a broader vision for emission-free city logistics, the city of Rotterdam plans to introduce a zero-emission zone in combination with urban consolidation centers (UCCs) on the outskirts of the city to generate a shift to zero-emission vehicles. For the design of this zero-emission zone, several research questions arise that require a systematic analysis of the impacts of the transition scenarios on freight demand patterns, the use and market shares of new (zero-emission) vehicles, and the impacts of truck flow and emissions. As a case study, we implemented heterogenous transition scenarios for each logistic segment into the Tactical Freight Simulator from the HARMONY project and analyzed the systemwide impacts. This model is multiagent, empirical, and shipment based and simulates long-term tactical choices (distribution channel choice, shipment size and vehicle type choice, sourcing) and short-term tactical choices (tour formation, delivery times). Results showed that the impact of UCCs is not trivial: we observed a small increase in vehicle kilometers traveled overall of +0.25%, which can be attributed to the rerouting of shipments through the UCCs. Calculations confirmed that emissions reduced dramatically, by 90%, inside the zero-emission zone. At the city scale this corresponds to a reduction of almost 10%, as most freight-related traffic is generated by the port and involves long-haul heavy goods vehicle transport that does not enter the city center. At a regional level, impact reduction was very small. More measures are needed if more ambitious reductions in emissions are to be achieved.
      Citation: Transportation Research Record
      PubDate: 2021-05-15T08:39:33Z
      DOI: 10.1177/03611981211012694
       
  • 3D-Printing of Ultra-High-Performance Concrete for Robotic Bridge
           Construction

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      Authors: Ali Javed, Islam M. Mantawy, Atorod Azizinamini
      Abstract: Transportation Research Record, Ahead of Print.
      Automation and robotics are integral parts of many industries but their potential for field implementation has not been significantly recognized by the construction industry. This is mainly attributed to conventional construction and design practices which undermine the benefits offered by these new technologies such as repetitions, precision, time savings, and increased safety. There is a need for advanced materials and 3D-printing systems which are capable of constructing structural elements with performance that emulates conventionally cast elements. This study presents a detailed framework and performance metrics for materials and 3D-printing systems for bridge applications. In addition, a study was carried out on ultra-high-performance concrete (UHPC) which showed sufficient extrudability and workability for 3D-printing applications. A 3D-printing system was developed for 3D-printing of continuous additive layers of UHPC with accelerated heat curing. Accelerated heat curing was used to enhance buildability, expedite the printing of the UHPC layers, and maximize the number of printed layers within the material open time. The effect of heat curing on material properties was also evaluated to obtain the optimal temperature to satisfy compressive strength requirements. This research effort aims to augment automated construction techniques and develop solutions to extend the applications of accelerated bridge construction.
      Citation: Transportation Research Record
      PubDate: 2021-05-14T08:34:28Z
      DOI: 10.1177/03611981211011645
       
  • Deploying and Integrating Smart Devices to Improve Work Zone Data for Work
           Zone Data Exchange

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      Authors: Skylar Knickerbocker, Varsha Ravichandra-Mouli, Archana Venkatachalapathy
      Abstract: Transportation Research Record, Ahead of Print.
      Connected temporary traffic control devices (cTTCDs) that provide their location and status are a new tool that infrastructure owners and operators can begin to use to improve the accuracy of work zone data. By improving work zone data, better information can be provided to the public. Publishing these data through the WZDx (Work Zone Data Exchange) aims to improve safety by notifying drivers and vehicles of the location of verified work zones. Connected devices such as smart arrow boards and connected cones have continued to increase in number in the market, but little has been done to determine the best method of integrating these devices into a department of transportation’s (DOT’s) system. An approach is presented that integrates deployed smart arrow boards to indicate actual conditions as part of a planned work zone by leveraging a DOT’s linear referencing system. This method does not require any additional effort from field staff and improves the locational and temporal accuracy of work zone information as part of a WZDx. When fully deployed, this system showed that smart arrow boards could be automatically associated with a work zone in controlled test scenarios as well as in a limited sample under real-world conditions. In real-world conditions, contractors did not need to provide additional information to associate the smart arrow board with the 511 work zone event. This effort represents a starting point for how cTTCDs could be integrated into DOT systems to improve work zone data accuracy.
      Citation: Transportation Research Record
      PubDate: 2021-05-14T08:30:49Z
      DOI: 10.1177/03611981211011481
       
  • Transit Users’ Mode Choice Behavior During Light Rail Transit Short-Term
           Planned Service Disruption

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      Authors: Muhammad Arslan Asim, Adam Weiss, Lina Kattan, S. C. Wirasinghe
      Abstract: Transportation Research Record, Ahead of Print.
      Planned service disruptions (PSDs) of light rail transit (LRT) improve service reliability, extend infrastructure’s life, and reduce the frequency and impact of unplanned service disruption caused by system failure. However, the literature on the impact of LRT PSDs on transit customers’ travel mode choice behavior is scarce relative to that on unplanned service disruptions. This study aimed to investigate transit customers’ mode choice behavior in response to short-term LRT PSD in the City of Calgary, AB, Canada. A stated preference survey was designed to gather respondents’ mode choices under a set of hypothetical scenarios. A mixed multinomial logit model was estimated using stated preference data. Findings of this study include: (i) stated LRT ridership dropped by about 35% during the examined short-term LRT service disruption; (ii) transit customers who hold a LRT payment pass (monthly, subsidized seniors, low income, and students) and are frequent weekend LRT users are more likely to stay with the LRT mode in case of short-term PSD; (iii) the value of time for transit users during short-term LRT PSD was found to be 11.76 $/h and 13.0 $/h for travel time (excluding wait time) and wait time during travel, respectively. A sensitivity analysis was conducted on key variables to predict choice probabilities of transit alternatives. Recommendations are made to improve Calgary Transit customers’ experience during short-term LRT PSDs.
      Citation: Transportation Research Record
      PubDate: 2021-05-13T09:41:33Z
      DOI: 10.1177/03611981211012421
       
  • Potential Benefits of Animal-Detecting Automatic Emergency Braking Systems
           Based on U.S. Driving Data

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      Authors: Jeremy A. Decker, Samantha H. Haus, Rini Sherony, Hampton C. Gabler
      Abstract: Transportation Research Record, Ahead of Print.
      In 2015, there were 319,195 police reported vehicle-animal crashes, resulting in 275 vehicle occupant fatalities. Animal-detecting automatic emergency braking (AEB) systems are a promising active safety measure which could potentially avoid or mitigate many of these crashes by warning the driver, utilizing automatic braking, or both. The purpose of this study was to develop and characterize a target population of vehicle-animal crashes applicable to AEB systems and to analyze the potential benefits of an animal-detecting AEB system. The study was based on two nationally representative databases, Fatality Analysis Reporting System and the National Automotive Sampling System’s General Estimates System, and a naturalistic driving study, SHRP 2. The target population was restricted to vehicle-animal crashes that were forward impacts or road departures and involved cars and light trucks, with no loss of control. Crash characteristics which may influence the performance of AEB such as lighting, weather, pre-crash movement, relation to junction, and first and worst harmful events, were analyzed. The study found that the major influences on the effectiveness of animal AEB systems were: weather, lighting, pre-crash movements, and the crash location. Six potential target populations were used to analyze the potential effectiveness of an animal AEB system, with effectiveness ranging between 21.6% and 97% of police reported crashes and between 4.1% and 50.8% of fatal vehicle-animal crashes. An AEB system’s ability to function in low light and poor weather conditions may enable it to avoid a substantially higher proportion of crashes.
      Citation: Transportation Research Record
      PubDate: 2021-05-13T09:39:34Z
      DOI: 10.1177/03611981211012416
       
  • Do We Need a Change in Road Winter Maintenance to Accommodate for
           Automated Vehicles' A State-of-the-Art Literature Review Considering
           Automated Vehicle Technology’s Usage of Road Infrastructure During
           Winter

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      Authors: Ingvild Ødegård, Alex Klein-Paste
      Abstract: Transportation Research Record, Ahead of Print.
      For automated vehicles to be allowed to join the modern car fleet, and, in the future, replace human drivers, they must be able to handle adverse weather, including snowy conditions. This literature review focuses on how automated vehicles utilize the road and how this use is suitable for winter maintenance strategies. Where global navigation satellite system (GNSS) service is unavailable, automated vehicles need bare roads to perform relative navigation based on real-time data about lane markings, obstacles, and road infrastructure. Snow-covered tracks hinder vehicle navigation and lane marking detection, which might generate wheel slippage that in turn causes emergency stop and challenging friction estimates. Although the entry of automated vehicles into the car fleet does not demand change in the strategies of winter maintenance, it does demand higher level of service than today. Maintaining an entire road network on which autonomous vehicles always can operate is tremendously expensive and likely not feasible. One solution could be to add another maintenance class in a bare road strategy, that is, an automated vehicle maintenance class with a high level of service and a set of operational criteria allowing automated vehicles to operate. The maintenance class should be used for certain main routes where there is a high frequency of automated vehicles. A model that recommends preferable routes to the destination based on current road conditions within the operational envelope should be provided to the automated vehicle system.
      Citation: Transportation Research Record
      PubDate: 2021-05-13T09:35:45Z
      DOI: 10.1177/03611981211012415
       
  • Development of a Multi-Distress Detection System for Asphalt Pavements:
           Transfer Learning-Based Approach

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      Authors: Naga Siva Pavani Peraka, Krishna Prapoorna Biligiri, Satyanarayana N. Kalidindi
      Abstract: Transportation Research Record, Ahead of Print.
      The major objective of this research was to develop a multi-distress detection system (MDDS) that is competent in detecting various asphalt pavement functional distresses simultaneously from video images using appropriate artificial intelligence techniques. You Only Look Once Version 4 (YOLOv4), a state-of-the-art objection detection architecture incorporated with transfer learning-based approach was utilized to quantify multiple severity-based distresses obtained from actual pavement condition images. Eighteen distress classes were defined consisting of three levels of severity pertinent to cracking, potholes, and patch deterioration. The customized MDDS algorithm was trained and tested on 1,518 images retrieved from three different datasets. During training, MDDS attained an average loss of 1.5123, and the validation mean average precision was reported to be 87.44% after 7,900 iterations. During the training process, the customized architecture transformed the training images and segmented them into two million images that potentially enhanced the probability of prediction even when the images are spatially transformed. The model detected multiple distresses in the pavement video clip at an average rate of 6.7 frames per second, which makes it suitable for real-time distress detection. It is envisioned that the novel real-time MDDS tested on diverse datasets could be used by roadway agencies to identify and quantify severity-based distress classes during the monitoring process itself, which ultimately reduces the time between data analysis, pavement forensic evaluation, and decision making on maintenance interventions.
      Citation: Transportation Research Record
      PubDate: 2021-05-13T09:31:22Z
      DOI: 10.1177/03611981211012001
       
  • Network Optimization of Railway Cold Chain Logistics Based on Freight
           Subsidy

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      Authors: Yu Lu, Xingfang Xu, Chuanzhong Yin, Yueyi Zhang
      Abstract: Transportation Research Record, Ahead of Print.
      The proportion of railway cold chain transportation in the overall cold chain logistics transportation market is relatively small in China. Freight subsidies and cold chain train operations are typically effective approaches to guide the public transit of cold chain cargo flow and grow the railway cold chain transportation market. We analyzed the cost structure of a cold chain transportation network. We established a network optimization model of the railway cold chain logistics based on a freight subsidy and designed an adaptive genetic–simulated annealing algorithm (A-SAGA). Taking the cold chain transportation between the Yangtze river delta urban agglomerations and the Chengdu–Chongqing city group as an example, we determined the optimal cold chain logistics transportation scheme using the traditional genetic algorithm and the A-SAGA. Moreover, we conducted sensitivity analysis on freight subsidies, train travel speeds, soft time windows, and carbon tax rates. The results showed that for medium- and long-distance cold chain transportation, the railway market share increased from 17.55% to 18.75% with an increase in the railway freight rate subsidy share from 0% to 30%. More cold chain goods were transported by rail when the soft time window or the carbon tax rate increased. Moreover, the railway market share increased from 17.55% to 43.75% with an increase in the train travel speed from 60 km/h to 120 km/h. Thus, compared with freight subsidy, increasing the train travel speed is a better approach to improve the competitiveness of railway cold chain logistics.
      Citation: Transportation Research Record
      PubDate: 2021-05-13T09:29:02Z
      DOI: 10.1177/03611981211011998
       
  • Passenger Expectations and Airport Service Quality: Exploring Customer
           Segmentation

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      Authors: George Christian Linhares Bezerra, Eliézer Mello de Souza, Anderson Ribeiro Correia
      Abstract: Transportation Research Record, Ahead of Print.
      Understanding customer expectations is key in any service context, including indentifying the differences between customer segments. Nonetheless, they remain underresearched topics in the airport industry, with limited empirical evidence on the nature of passenger expectations and how they relate to the service experienced. Therefore, the objectives of this research were twofold: first, to estimate a structural model of the relationships between customer expectations and airport service quality dimensions; second, to examine the differences between groups of passengers. Sample data from a survey administered to passengers at one of Brazil’s largest airports, in São Paulo, were used for structural equation modeling analyses. The results provided models with a good fit to the data. The findings for nonfrequent passengers showed that the effects of expectations on airport service quality were significant for all the service quality dimensions examined, whereas frequent passengers only revealed a significant relationship between expectation and the “processes” dimension. Theoretical and practical contributions to airport planning and management are discussed in light of the findings.
      Citation: Transportation Research Record
      PubDate: 2021-05-13T09:25:27Z
      DOI: 10.1177/03611981211011992
       
  • Integrated Herfindahl–Hirschman Index, Compromise Programming, and
           ε-Constraint Method For Multicriteria Performance-Based Transportation
           Budget Allocation

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      Authors: Tung Q. Truong, Ji Zhang, Zongzhi Li, Lu Wang
      Abstract: Transportation Research Record, Ahead of Print.
      This paper introduces a new method for multicriteria performance-based transportation budget allocation. First, the Herfindahl–Hirschman Index (HHI) that has long been used in economics for measuring the level of monopolization in a marketplace is employed to derive the relative weights of multiple non-commensurable transportation performance criteria. Next, a compromise programming (CP) model is formulated to help transform the multicriteria optimization formulation for transportation budget allocation to a single-objective optimization model solvable by minimizing the Chebyshev distance to the ideal levels of performance targets associated with individual performance criteria. Finally, the ε-constraint trade-off analysis method is incorporated into the combined use of HHI and CP framework to iteratively derive the optimal decision outcome. Six-year data on candidate investment projects proposed for a U.S. state-maintained rural Interstate highway system along with data details of the available budget is used in a computational study for method application. Comparative analysis of decision outcomes is conducted with the STEP method for cross validation. It has revealed that the proposed HHI-CP ε-constraint method outperforms the existing method and can be adopted by state and local transportation agencies to carry out effective budget allocation.
      Citation: Transportation Research Record
      PubDate: 2021-05-13T09:22:36Z
      DOI: 10.1177/03611981211011648
       
  • Identification of Optimal Left-Turn Restriction Locations using Heuristic
           Methods

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      Authors: Murat Bayrak, Vikash V. Gayah
      Abstract: Transportation Research Record, Ahead of Print.
      Restricting left turns throughout a network improves overall flow capacity by eliminating conflicts between left-turning and through-moving vehicles. However, doing so requires vehicles to travel longer distances. Implementing left-turn restrictions at only a subset of locations can help balance this tradeoff between increased capacity and longer trips. Unfortunately, identifying exactly where these restrictions should be implemented is a complex problem because of the many configurations that must be considered and interdependencies between left-turn restriction decisions at adjacent intersections. This paper compares three heuristic solution algorithms to identify optimal location of left-turn restrictions at individual intersections in perfect and imperfect grid networks. Scenarios are tested in which restriction decisions are the same for all intersection approaches and only the same for approaches in the same direction. The latter case is particularly complex as it increases the number of potential configurations exponentially. The results suggest all methods tested can be effectively used to solve this problem, although the hybrid method proposed in this paper appears to perform the best under scenarios with larger solution spaces. The proposed framework and procedures can be applied to realistic city networks to identify where left-turn restrictions should be implemented to improve overall network operations. Application of these methods to square grid networks under uniform demand patterns reveal a general pattern in which left turns should be restricted at central intersections that carry larger vehicle flows but allowed otherwise. Such findings can be used as a starting point for where to restrict left turns in more realistic networks.
      Citation: Transportation Research Record
      PubDate: 2021-05-13T09:20:12Z
      DOI: 10.1177/03611981211011647
       
  • Preserving Privacy with Federated Learning in Route Choice Behavior
           Modeling

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      Authors: Yonghyeon Kweon, Bingrong Sun, B. Brian Park
      Abstract: Transportation Research Record, Ahead of Print.
      While big data helps improve decision-making and model developments, it often runs into privacy concerns. An example would be retrieving drivers’ origin and destination information from smartphone navigation apps for developing a route choice behavior model. To conserve privacy, yet to take advantage of big data in navigation applications, the authors propose to apply a federated learning approach, which has shown promising application in predicting smartphone keyboard’s next word without sending text to the server. Additional benefits of using federated learning is to save on data communications, by sending model parameters instead of entire raw data, and to distribute the computational burden to each smartphone instead of to the main server. The results from real-world route navigation usage data from about 30,000 drivers over one year showed that the proposed federated learning approach was able to achieve very similar accuracy to the traditional centralized global model and yet assures privacy.
      Citation: Transportation Research Record
      PubDate: 2021-05-13T09:17:38Z
      DOI: 10.1177/03611981211011162
       
  • Evaluating Changes in Spatial Accessibility to Airports in Turkey between
           2000 and 2018

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      Authors: Muhammed Ziya Paköz, Adem Sakarya
      Abstract: Transportation Research Record, Ahead of Print.
      The present study aims to investigate the changes that occurred between 2000 and 2018 with regard to spatial accessibility to airports for each district in Turkey. Within this scope, first, the service coverage area of each airport within 1 to 2 h travel time by car for 2000, 2009, and 2018 using the available road networks for the given years is evaluated and each district that can reach at least one airport within 1 to 2 h by car determined. Secondly, the catchment areas of each airport are defined based on geographical distribution and the catchment populations of airports found. Thirdly, the regionalization coefficient for each airport in the given years is calculated to understand the availability of each airport by comparing the catchment area population with the number of domestic passengers. Finally, a gravity-based formula is employed to measure the spatial accessibility value of each district to the airports within the catchment area of 2 h travel time in the given years. The main findings from the study provide clues about the direction of future policies. The last airports to open have reduced the maximum distance covered, especially in eastern Turkey; consequently, airports’ catchment populations have shrunk. However, the regionalization coefficients of airports located in regional centers and hub cities have increased in consequence of the increase in the number of air passengers over the given period. In summary, travel time to main hubs and airports’ total catchment populations have had combined effects on the number of air passengers and spatial accessibility values of districts in Turkey.
      Citation: Transportation Research Record
      PubDate: 2021-05-12T02:09:10Z
      DOI: 10.1177/03611981211011649
       
  • Strain Sweep Fatigue Testing of Sand Asphalt Mortar to Investigate the
           Effects of Sample Geometry, Binder Film Thickness, and Testing Temperature
           

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      Authors: Lilian Ribeiro de Rezende, Santosh Reddy Kommidi, Yong-Rak Kim, Mahdieh Khedmati
      Abstract: Transportation Research Record, Ahead of Print.
      This study evaluated the viscoelastic fatigue behavior of binder using strain sweep fatigue testing of cylindrical sand asphalt mortar (SAM) samples. The SAM samples can represent the realistic film thickness (such as 10–70 μm thick) of the binder in mixtures, while testing repeatability-efficiency can still be met as a result of the use of a standard sand as a load carrier between binder films. A proper testing protocol is still under development, and one of the unknowns in the field is a set of testing conditions that can provide repeatable and case-sensitive test results. Toward that end, SAM samples with different dosages of binder in three geometries were tested at varying temperatures in this study. A PG 64-34 binder was used, and a strain sweep test using a dynamic shear rheometer was conducted to compare the test results from the different cases. Four parameters resulting from the SAM testing were examined: two accounting for material linear viscoelastic behavior and two accounting for fatigue damage characteristics. The parameters were incorporated with statistical analyses to quantitatively evaluate data variability and sensitivity influenced by the binder film thickness, SAM specimen geometry, and testing temperature. The coefficient of variation was less than 20% for all the cases, which indicated the validity of the SAM method attempted in this study. Results also indicated that fatigue behavior was independent of the SAM geometries used in this study, while binder film thickness and testing temperature significantly affected test results.
      Citation: Transportation Research Record
      PubDate: 2021-05-12T02:07:09Z
      DOI: 10.1177/03611981211011646
       
  • Synchronized Entry-Traffic Flow Prediction for Regional Expressway System
           Based on Multidimensional Tensor

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      Authors: Hong Gao, Zengjie Wang, Zhenjun Yan, Zhaoyuan Yu, Wen Luo, Linwang Yuan
      Abstract: Transportation Research Record, Ahead of Print.
      Predicting entry-traffic flows synchronously could enable inferences about the changing trends and spatial structure of dynamic traffic flows in an expressway network. This research develops a synchronized entry-traffic flow prediction method for regional expressway systems. The new method first organizes numerous entry-traffic flows as a three-dimensional (time slots, spatial locations, and vehicle types) tensor, then applies tensor decomposition to extract their temporally changing features. After forecasting the temporally changing features, predicted values of entry-traffic flows can be calculated synchronously by tensor reconstruction. Data from hourly entry-traffic flows involving nine vehicle types and 201 spatial locations in a regional expressway system of China are used to discuss the performance of this new method. The results show that the new method could obtain prediction results with high overall accuracy. Comparative experiments indicate that the new method and existing methods (autoregressive integrated moving average, or ARIMA, and Holt-Winters) could generate prediction results with similar accuracy. However, the proposed method has the advantage of reducing the number of time series that need to be handled in the prediction of numerous entry-traffic flows for regional expressway systems. This method might be helpful for administrators to guide and manage vehicles so that they enter the expressway system effectively.
      Citation: Transportation Research Record
      PubDate: 2021-05-12T02:05:50Z
      DOI: 10.1177/03611981211011169
       
  • Optimal Approach to Improving the Utilization of Regenerative Energy
           Considering Power Profile

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      Authors: Juanjuan Cai, Jing Xun, Xiangyu Ji, Yue Lei
      Abstract: Transportation Research Record, Ahead of Print.
      Urban rail transit (URT) develops rapidly in modern cities, and its energy efficiency attracts extensive attention. The utilization of regenerative energy (URE) is an important method for energy-efficient operation of URT. Regenerative braking is an energy recovery mechanism that slows down a moving train by converting its kinetic energy into electric energy. The electric energy can be utilized for other trains to accelerate in a cooperative way. To take full advantage of the regenerative energy, an energy calculation method which considers regenerative braking power to optimize the timetable is proposed in this paper. First, four operating modes of URE are defined and an integer programming model is formulated. Second, a branch and bound algorithm is designed to solve the optimal timetable in different scenarios. Third, the model is evaluated based on the operation data from the Yanfang Line, Beijing Metro, China. For peak hours, the results illustrate that the proposed method can significantly improve URE by 73.7% compared with the original timetable. Also, URE can be improved by 46.3% for off-peak hours. Finally, the comparison between the proposed method and the method based on the kinetic energy theorem is given. The simulation results illustrate that the proposed method could increase URE by 29.7% and 9.9% for peak and off-peak hours scenarios, respectively, in comparison with the method based on the kinetic energy theorem.
      Citation: Transportation Research Record
      PubDate: 2021-05-12T02:05:23Z
      DOI: 10.1177/03611981211004976
       
  • Drivers Still Have Limited Knowledge About Adaptive Cruise Control Even
           When They Own the System

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      Authors: Chelsea A. DeGuzman, Birsen Donmez
      Abstract: Transportation Research Record, Ahead of Print.
      Much of the existing research on drivers’ understanding of adaptive cruise control (ACC), a type of advanced driver assistance system, was conducted several years ago. Through an online survey, this study aimed to assess ACC knowledge among ACC owners and non-owners now that this system is more widely available. Along with knowledge of ACC features and limitations, demographic information, experience with technology, and experience with ACC (for owners) were also collected to investigate which factors predicted knowledge of ACC features and limitations. Results showed that owners today may have a better understanding of some of the main limitations of ACC compared with research conducted over 10 years ago. However, a large percentage of owners still had misperceptions about their ACC system. While owners had a slightly higher percentage of correct answers overall, they did not differ from non-owners in their knowledge of limitations. As this technology is becoming more common, even non-owners may be becoming aware of common limitations; owning and using ACC does not seem to result in a better system understanding. Higher income was associated with a higher percentage of correct responses on the ACC knowledge questionnaire for both owners and non-owners, and for non-owners, higher education level was also significantly associated with a higher percentage of correct responses. Future research should focus on developing training materials that are accessible to all drivers, so that drivers in lower education and income groups are also supported to understand how advanced driver assistance systems work and benefit from these technologies.
      Citation: Transportation Research Record
      PubDate: 2021-05-11T07:30:04Z
      DOI: 10.1177/03611981211011482
       
  • DistTune: Distributed Fine-Grained Adaptive Traffic Speed Prediction for
           Growing Transportation Networks

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      Authors: Ming-Chang Lee, Jia-Chun Lin, Ernst Gunnar Gran
      Abstract: Transportation Research Record, Ahead of Print.
      Over the past decade, many approaches have been introduced for traffic speed prediction. However, providing fine-grained, accurate, time-efficient, and adaptive traffic speed prediction for a growing transportation network where the size of the network keeps increasing and new traffic detectors are constantly deployed has not been well studied. To address this issue, this paper presents DistTune based on long short-term memory (LSTM) and the Nelder-Mead method. When encountering an unprocessed detector, DistTune decides if it should customize an LSTM model for this detector by comparing the detector with other processed detectors in the normalized traffic speed patterns they have observed. If a similarity is found, DistTune directly shares an existing LSTM model with this detector to achieve time-efficient processing. Otherwise, DistTune customizes an LSTM model for the detector to achieve fine-grained prediction. To make DistTune even more time-efficient, DisTune performs on a cluster of computing nodes in parallel. To achieve adaptive traffic speed prediction, DistTune also provides LSTM re-customization for detectors that suffer from unsatisfactory prediction accuracy due to, for instance, changes in traffic speed patterns. Extensive experiments based on traffic data collected from freeway I5-N in California are conducted to evaluate the performance of DistTune. The results demonstrate that DistTune provides fine-grained, accurate, time-efficient, and adaptive traffic speed prediction for a growing transportation network.
      Citation: Transportation Research Record
      PubDate: 2021-05-10T02:13:49Z
      DOI: 10.1177/03611981211011170
       
  • Use of Bivariate Random-Parameter Probit Model to Analyze the Injury
           Severity of Highway Traffic Crashes Involving School-Age Children

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      Authors: Jaeyoung Lee, Suyi Mao, Mohamed Abdel-Aty, Wen Fu
      Abstract: Transportation Research Record, Ahead of Print.
      Traffic safety has been a serious public health issue. According to the World Health Organization, annual traffic fatalities and non-fatal injuries are 1.35 million and 20 to 50 million, respectively, worldwide. Vehicle crashes, in particular, are the leading cause of the death of children in the world. This study aims to analyze the injury severity level of drivers and school-age passengers and to identify contributing factors, focusing on the effects of driver characteristics on the severity of injuries to the driver and child passenger. A bivariate model is adopted to capture unobserved shared factors between the driver’s and child’s injury severity levels. The results indicate that the factors contributing to the injury severity level of drivers and school-age passengers are quite different, and some driver characteristics significantly affect the injury severity of the child passenger. The findings from this study can contribute to an efficient strategic plan to reduce the injury severity of vehicle occupants.
      Citation: Transportation Research Record
      PubDate: 2021-05-10T01:55:09Z
      DOI: 10.1177/03611981211011620
       
  • MAP-21 to FAST Act: Did the Transportation Infrastructure Finance and
           Innovation Act Program Better Support High-Risk Transportation
           Infrastructure Projects'

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      Authors: Narae Lee, Jonathan L. Gifford
      Abstract: Transportation Research Record, Ahead of Print.
      The Transportation Infrastructure Finance and Innovation Act (TIFIA) program acts as the U.S. federal government’s largest direct financing program for domestic transportation infrastructure development. Employing a direct credit support mechanism, the program aims to leverage municipal and private investments to deliver higher-risk transportation projects that nevertheless offer important benefits for the public. Recent policy changes under the 2015 FAST Act may have altered the market-leveraging function, but existing literature has not evaluated this possibility. As a result, this research evaluated the program’s market-leveraging outcomes by investigating whether and how the beneficiary projects’ risk profiles, as measured by project credit ratings, changed between the MAP-21 and FAST Act policy periods. The program will produce higher leveraging effects when supporting lower-rated projects since the riskier projects tend to suffer from higher interest rates in financial markets. After constructing a project-level dataset, the authors employed Linear Probability Model and Treatment Effect regressions to assess the possible relationship between the FAST Act amendment and changes to the TIFIA program’s risk profile. The study also employed a Binary Logit regression for sensitivity analysis. The empirical findings suggest that the proportion of TIFIA-selected projects with AAA/AA/A versus BBB ratings did not differ significantly between the MAP-21 and FAST Act periods. However, the program allocated a larger proportion of its lending capacity to AAA/AA/A projects during the FAST Act period. Given these findings, policymakers may wish to rebalance the program’s objectives if the market-leveraging function remains a priority.
      Citation: Transportation Research Record
      PubDate: 2021-05-10T01:54:16Z
      DOI: 10.1177/03611981211011644
       
  • Modeling Arrival Flight Times within the Terminal Airspace

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      Authors: Osama Alsalous, Susan Hotle
      Abstract: Transportation Research Record, Ahead of Print.
      Air traffic management efficiency in the descent phase of flights is a key area of interest in aviation research for the United States, Europe, and recently other parts of the world. The efficiency of arrival travel times within the terminal airspace is one of nineteen key performance indicators defined by the Federal Aviation Administration (FAA) and the International Civil Aviation Organization, typically within 100 nmi of arrival airports. This study models the relationship between travel time within the terminal airspace and contributing factors using a multivariate log-linear model to quantify the impact that these factors have on the total travel time within the last 100 nmi. The results were compared with the baseline set of variables that are currently used for benchmarking at the FAA. The analyzed data included flight and weather data from January 1, 2018 to March 31, 2018 for five airports in the United States: Chicago O’Hare International Airport, Hartsfield-Jackson Atlanta International, San Francisco International Airport, John F. Kennedy International Airport, and LaGuardia Airport. The modeling results showed that there is a significant improvement in prediction accuracy of travel times compared with the baseline methodology when additional factors, such as wind, meteorological conditions, demand and capacity, ground delay programs, market distance, time of day, and day of week, are included. Root mean squared error values from out-of-sample testing were used to measure the accuracy of the estimated models.
      Citation: Transportation Research Record
      PubDate: 2021-05-10T01:50:54Z
      DOI: 10.1177/03611981211011487
       
  • Laboratory and Field Evaluation of Pre-Treated Dry-Process Rubber-Modified
           Asphalt Binders and Dense-Graded Mixtures

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      Authors: Punyaslok Rath, Hamed Majidifard, Behnam Jahangiri, Shishi Chen, William G. Buttlar
      Abstract: Transportation Research Record, Ahead of Print.
      Pre-treatment of ground tire rubber is emerging as a popular method to incorporate rubber particles in dense-graded asphalt mixtures. This study investigates the effects of a chemically engineered Dry-Process Ground Tire Rubber (DP-GTR) modification in asphalt binders and mixtures. The DP-GTR is comprised of rubber particles measuring 400 to 600 µm in diameter (minus #30 mesh) coated with a non-elastomeric liquid. No change in aggregate gradation is necessary in DP-GTR modification of asphalt mixtures. In this study, the effects of DP-GTR modification on binder properties were measured by dynamic shear rheometer, Multiple Stress Creep and Recovery (MSCR), and bending beam rheometer tests. Additionally, mixture properties measured by three cracking tests: Disk-shaped Compact Tension (DC[T]) test, Illinois Flexibility Index, and indirect tensile asphalt cracking test and one rutting test (Hamburg wheel track test) were evaluated. Results showed: (a) 10–12°C bump on binder high temperature performance grade with 10% DP-GTR modification by weight of binder; (b) improvement in non-recoverable compliance in MSCR test indicated higher rut resistance; (c) increase in DC(T) fracture energy at low temperatures; (d) decrease in rut depth; and (e) decrease in flexibility index and cracking test index. Field performance of the chemically treated DP-GTR sections located in different states was examined to address discrepancies observed in the cracking tests. The cracking and rutting performance of all the field sections was good-to-excellent, suggesting that some of the currently popular simple cracking tests may not be able to properly assess the cracking resistance inherent in GTR-modified asphalt mixtures.
      Citation: Transportation Research Record
      PubDate: 2021-05-10T01:50:15Z
      DOI: 10.1177/03611981211011480
       
  • Florida Department of Transportation’s Enhanced Hydroplaning
           Prediction Tool

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      Authors: Hyung Suk Lee, Mateo Carvajal, Charles Holzschuher, Bouzid Choubane
      Abstract: Transportation Research Record, Ahead of Print.
      Florida Department of Transportation (FDOT) recently developed and implemented a new hydroplaning prediction (HP) program for predicting the traveling speed at which a vehicle would start hydroplaning. The tool was developed as part of the effort to reduce hydroplaning accidents and is being used during the roadway design phase to evaluate the hydroplaning potential of Florida’s roadways. This paper presents an overview of FDOT’s HP program and demonstrates how it may be used. The tool incorporates a total of four water film thickness models and three hydroplaning speed models developed in the past, allowing for a total of 12 model combinations for the hydroplaning analysis. The tool also offers different analysis options that may be used to meet a variety of FDOT’s needs. As demonstrated in this paper, the primary use of the new HP tool is for checking the final geometric roadway design parameters for hydroplaning potential. In addition, the HP program can also be used as a forensic investigation tool for identifying specific locations that exhibit higher potential for hydroplaning.
      Citation: Transportation Research Record
      PubDate: 2021-05-10T01:46:06Z
      DOI: 10.1177/03611981211011479
       
  • Impact of Geometry and Operations on Left-Turn Gap Acceptance at
           Signalized Intersections with Permissive Indication

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      Authors: Boris Claros, Madhav Chitturi, Andrea Bill, David A. Noyce
      Abstract: Transportation Research Record, Ahead of Print.
      Critical and follow-up headways are the foundation for estimating the saturation flow of permissive left-turns at signalized intersections. Current critical and follow-up headways recommended in the 2016 Highway Capacity Manual (HCM) are based on limited data collected from five intersections in Texas in the 1970s. This study analyzed over 2,500 left-turning vehicles at 45 intersection approaches, provides insights into gap acceptance parameters, and evaluates the effect of different site-specific factors. Video data were collected and processed from different geographical regions in the United States—Arizona, Florida, North Carolina, Virginia, and Wisconsin. Using the maximum likelihood method to estimate gap acceptance parameters, the mean critical headway was 4.87 s and the mean follow-up headway was 2.73 s. To account for site-specific characteristics, the effect of several geometric and operational variables on critical and follow-up headway were explored. Through a meta-regression analysis, the posted speed limit and width of opposing travel lanes were found to have a significant effect on gap acceptance parameters. Results showed that with decreasing posted speed limit and width of opposing lanes, critical and follow-up headways also decreased, resulting in greater saturation flows. When site-specific saturation flow estimates were compared with HCM saturation flow estimates, the differences ranged from −30% to +23%. This paper quantifies and illustrates the impact of site-specific characteristics on gap acceptance parameters and saturation flow.
      Citation: Transportation Research Record
      PubDate: 2021-05-10T01:40:14Z
      DOI: 10.1177/03611981211011476
       
  • Long-Distance Airport Substitution and Air Market Leakage: Empirical
           Investigations in the U.S. Midwest

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      Authors: Kaleab Woldeyohannes Yirgu, Amy M. Kim, Megan S. Ryerson
      Abstract: Transportation Research Record, Ahead of Print.
      Following airline mergers and network reorganizations aimed at reducing operational costs, consolidated air services at large hub airports have encouraged air travelers to forego use of their smaller local airports to access large hub airports offering superior air services farther away. This study investigates airport leakage in areas of Wisconsin and Michigan served by small airports, where air travelers may leak to neighboring large hubs. Using a proximity-based service area definition, three airports experiencing leakage are identified, and a hierarchical logit airport choice model is applied that accounts for air service characteristics and access distance for travelers coming from these airports’ service areas. Results show that a similar mean number of flight legs at both the local and substitute (large hub) airports will encourage leakage at Dane County Regional and Gerald R. Ford International airports, indicating that adding direct flights alone will not be sufficient to combat leakage. Comparable access distances to local and substitute airports have opposite effects on the local markets of Gerald R. Ford International and Milwaukee Mitchell International airports—promoting leakage at the former but discouraging it at the latter. Furthermore, proportional increases in airfares at local airports lead to uneven losses of markets in investigated service areas. Overall, the study provides empirical evidence of long-distance airport leakage in parts of the U.S. Midwest, and how its implications can be used by small airports seeking to further understand and respond to travelers’ airport choices within their local markets.
      Citation: Transportation Research Record
      PubDate: 2021-05-08T10:19:22Z
      DOI: 10.1177/03611981211010797
       
  • Speeds of Right-Turning Vehicles at Signalized Intersections during Green
           or Yellow Phase

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      Authors: Kay Fitzpatrick, Michael P. Pratt, Raul Avelar
      Abstract: Transportation Research Record, Ahead of Print.
      The operation and design of signalized intersections involves tradeoffs between operational efficiency and safety for a variety of users, including motorists, pedestrians, and bicyclists. Additionally, the mix of vehicle types in the fleet sometimes requires special considerations. These concerns especially apply to the selection of curb radius at the corners, where right-turning vehicles operate close to pedestrians. Larger curb radii accommodate the swept paths of trucks and allow right turns to occur at higher speeds but may compromise safety and security for pedestrians by increasing the crossing distance and increasing the frequency of higher-speed turns. The authors collected right-turn vehicle speeds at 31 urban signalized intersection approaches in Texas with radii ranging from 15 to 70 ft. The authors calibrated a model to predict right-turn speeds as a function of site characteristics including curb radius, leading headway, vehicle type (car versus truck), maneuver of the preceding vehicle (through versus right turn), and signal indication (yellow or green). The analysis results indicate that right-turn speeds increase slightly with increasing radius, if the preceding vehicle proceeds through (rather than turning right) at the intersection, or if the signal indication is yellow rather than green. The calculated 85th percentile turning speed is generally higher than the assumed speed calculated using the radius of curvature equation. These trends should be considered if the intersection is expected to have notable volumes of pedestrians or trucks, as lower speeds are desirable for pedestrian safety, but larger radii may be necessary to accommodate turning trucks.
      Citation: Transportation Research Record
      PubDate: 2021-05-07T06:29:13Z
      DOI: 10.1177/03611981211011642
       
  • Precision Scheduled Railroading and the Need for Improved Estimates of
           Yard Capacity and Performance Considering Traffic Complexity

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      Authors: C. Tyler Dick
      Abstract: Transportation Research Record, Ahead of Print.
      Multiple North American freight railroads have adopted concepts of Precision Scheduled Railroading (PSR) that attempt to reduce costs by maximizing train length and minimizing railcar transit time. To achieve these objectives, PSR emphasizes pre-blocking traffic and operating general-purpose trains. These changes have altered the nature of operations at many classification yards, leading to yard closures and conversions to different yard types. Difficulty in implementing PSR-inspired operating practices at yards suggests the industry requires improved estimates of classification yard performance and capacity. While volume-based approaches may be adequate when yard operations are consistent with historical experience, it is hypothesized that approaches considering overall traffic complexity will offer improved predictions when changes are also made to the number of blocks and trains assembled in the yard. An original simulation model of a classification yard pull-down process is used to investigate this hypothesis. The simulation results suggest that a combination of factors describing yard traffic complexity can be a better predictor of yard performance than volume alone. The results are also transformed into a capacity constraint that describes the interaction between the maximum allowable daily number of railcars, blocks, and trains processed by a classification yard. Better understanding of these relationships can aid practitioners and researchers in improving network blocking models and developing train plans that properly use available yard capacity under PSR and other operating plans, reducing the likelihood of future network disturbances and congestion events.
      Citation: Transportation Research Record
      PubDate: 2021-05-07T06:27:33Z
      DOI: 10.1177/03611981211011486
       
  • Balancing the Service Benefits and Mainline Delay Disbenefits of Operating
           Shorter Freight Trains

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      Authors: Adrian Diaz de Rivera, C. Tyler Dick, Matthew M. Parkes
      Abstract: Transportation Research Record, Ahead of Print.
      Advanced train control systems enabling single-person crews or driverless trains promise to significantly reduce the fixed costs of operating a train, removing a strong incentive for longer trains. For carload freight traffic, operating a given number of railcars in shorter trains enables railroads to improve service quality and revenue through increased train frequencies or more direct trains bypassing intermediate classification yards. However, operating shorter trains increases the total number of trains on existing rail corridors, exacerbating congestion and decreasing network fluidity. Rail Traffic Controller simulation software is used to quantify the potential mainline delay impacts and relative capacity consumption of shorter trains. Different combinations of train length and train type heterogeneity are tested on representative single-track freight corridors. Results indicate that train control systems with moving blocks can mitigate some of the mainline delay impacts of shorter trains, particularly at a high traffic volume, with a mix of train types and a greater proportion of railcars traveling on short trains. Mid-siding crossovers can further boost the effectiveness of moving blocks in managing complex train conflicts caused by train type heterogeneity. Simulation results are used to perform an example railcar transit time estimation illustrating the trade-off between yard connection time benefits and mainline delay disbenefits, and the thresholds at which different operating strategies produce a net transit time benefit. Understanding the mainline delay impacts of shorter trains can assist railroad practitioners formulating long-term capital investment plans, developing future operating strategies, and improving service quality and market share through a short train philosophy.
      Citation: Transportation Research Record
      PubDate: 2021-05-07T06:24:11Z
      DOI: 10.1177/03611981211011484
       
  • Multi-Objective Evaluation Model of Single-Lane Roundabouts

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      Authors: Hend Ahmed, Said M. Easa
      Abstract: Transportation Research Record, Ahead of Print.
      Mobility, safety, and environmental sustainability are priorities in the geometric design of roundabouts. This paper presents a multi-objective optimization model that determines the geometric design elements of single-lane roundabouts using all three objectives. The user can specify weights for the objectives, or the model can determine the optimal weights. Mobility is defined in terms of roundabout delay and modeled using the United Kingdom empirical model. Safety is modeled in terms of collision frequency based on the methodology of the Highway Safety Manual. Environmental sustainability is represented by vehicle emissions (nitrogen oxides, hydrocarbons, carbon dioxide, and carbon monoxide) and is modeled using the vehicle-specific power methodology. The proposed model directly identifies the optimal geometric dimensions (decision variables) of the roundabout, including entry width, exit width, approach half-width, circulatory width, effective flare length, entry radius, entry angle, and inscribed circle diameter. The input data to the model include traffic data, site conditions, and limitations based on design guidelines. Application of the proposed model is illustrated using two actual roundabouts. The comparison results show that the proposed model provides substantial improvements in safety, mobility, and environmental sustainability compared with existing conditions. In addition, the model requires much less effort to apply compared with the traditional iterative method, and as such should be of interest to highway designers.
      Citation: Transportation Research Record
      PubDate: 2021-05-07T06:22:52Z
      DOI: 10.1177/03611981211011478
       
  • Dynamically Collected Local Density using Low-Cost Lidar and its
           Application to Traffic Models

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      Authors: Azhagan Avr, Shams Tanvir, Nagui M. Rouphail, Ishtiak Ahmed
      Abstract: Transportation Research Record, Ahead of Print.
      This article demonstrates the use of traffic density observations collected dynamically in the vicinity of probe vehicles. Fixed position sensors cannot capture the longitudinal evolution of local traffic density in the corridor. In this research, dynamic traffic density observations were collected in a naturalistic driving setting that was free of any controlled experiment biases. Speed from global positioning system and space headway from a light detection and ranging module was collected on one arterial and one freeway segment, 2 and 4 mi long, respectively. The combined data frequency was approximately 3 Hz. Space headway was used to estimate the local density and consequently to identify the density of a specific location in a corridor. Besides, driver behavior was characterized using the relationship between instantaneous speed and local density under different regimes of the Wiedemann car-following model. Macroscopic traffic stream models were used to investigate the relationship between dynamically collected instantaneous speed and local density. Using the longitudinal evolution of density, precise local density across the corridor can be obtained along with the leader and follower trajectories. A method to identify driver behavior across density ranges was developed for different facility types using a microscopic relationship between instantaneous speed and local density. Overall driving behavior on the freeway segment can be represented by translating the instantaneous speed and local density relationship to macroscopic stream models.
      Citation: Transportation Research Record
      PubDate: 2021-05-07T06:20:51Z
      DOI: 10.1177/03611981211010184
       
  • Driver Expectations toward Strategic Routing

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      Authors: Alexander Kröller, Falk Hüffner, Łukasz Kosma, Katja Kröller, Mattia Zeni
      Abstract: Transportation Research Record, Ahead of Print.
      Strategic Routing is a traffic intervention mechanism. To reduce traffic in a certain area, drivers are asked to take a pre-defined route diverting them from the area, even though this increases their travel time. This can be implemented with navigation apps or in-dash navigation from navigation service providers such as TomTom or Google. Triggered by a traffic authority, the driver receives information through the service provider’s infrastructure and user interface about a new route and potentially a reward. In this work, we investigate the dynamics between traffic authority, service provider, and end user by analyzing user expectations. Ultimately, service providers are competing for customers. They can, therefore, only implement strategic routing if it appeals to drivers rather than scares them away. We report on the insights of a two-stage study with 457 participants, exploring what kind of strategic routing interventions are appreciated by drivers. We find that drivers report a high interest in seeing diversion suggestions, even when they are not inclined to take them. However, they are unwilling to have their route adapted automatically. Important factors affecting drivers’ willingness to divert are the reason for the detour and the additional driving time. Incentives do increase the efficacy, but only marginally increase user appreciation, indicating that users may mistrust strategic routing that relies too strongly on incentives.
      Citation: Transportation Research Record
      PubDate: 2021-05-07T06:18:49Z
      DOI: 10.1177/03611981211006426
       
  • Hidden Markov Model of Lane-Changing-Based Car-Following Behavior on
           Freeways using Naturalistic Driving Data

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      Authors: Li Zhao, Laurence Rilett, Mm Shakiul Haque
      Abstract: Transportation Research Record, Ahead of Print.
      This paper develops a methodology for simultaneously modeling lane-changing and car-following behavior of automated vehicles on freeways. Naturalistic driving data from the Safety Pilot Model Deployment (SPMD) program are used. First, a framework to process the SPMD data is proposed using various data analytics techniques including data fusion, data mining, and machine learning. Second, pairs of automated host vehicle and their corresponding front vehicle are identified along with their lane-change and car-following relationship data. Using these data, a lane-changing-based car-following (LCCF) model, which explicitly considers lane-change and car-following behavior simultaneously, is developed. The LCCF model is based on Gaussian-mixture-based hidden Markov model theory and is disaggregated into two processes: LCCF association and LCCF dissociation. These categories are based on the result of the lane change. The overall goal is to predict a driver’s lane-change intention using the LCCF model. Results show that the model can predict the lane-change event in the order of 0.6 to 1.3 s before the moment of the vehicle body across the lane boundary. In addition, the execution times of lane-change maneuvers average between 0.55 and 0.86 s. The LCCF model allows the intention time and execution time of driver’s lane-change behavior to be forecast, which will help to develop better advanced driver assistance systems for vehicle controls with respect to lane-change and car-following warning functions.
      Citation: Transportation Research Record
      PubDate: 2021-05-07T06:17:06Z
      DOI: 10.1177/0361198121999382
       
  • Prioritizing Pedestrian and Bicyclist Count Locations for Volume
           Estimation

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      Authors: Jessica Schoner, Frank Proulx, Katherine Knapp de Orvañanos, Brian Almdale
      Abstract: Transportation Research Record, Ahead of Print.
      As data collection programs grow, cities need a way to systematically deploy counting equipment in a way that ensures robust pedestrian and bicyclist volume data are collected across a spectrum of use patterns and infrastructure contexts. This paper presents the findings from a deep dive into pedestrian and bicyclist volumes and exposure, including statistical modeling, as well as translating the outputs into an algorithm for systematically growing Seattle Department of Transportation’s nonmotorized count data collection program. The data collection location prioritization algorithm described in this paper provides a roadmap for cities and other agencies as they build their nonmotorized data collection programs.
      Citation: Transportation Research Record
      PubDate: 2021-05-06T12:47:47Z
      DOI: 10.1177/03611981211011164
       
  • Vehicle Dimensions Based Passenger Car Classification using Fuzzy and
           Non-Fuzzy Clustering Methods

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      Authors: Naghmeh Niroomand, Christian Bach, Miriam Elser
      Abstract: Transportation Research Record, Ahead of Print.
      There has been globally continuous growth in passenger car sizes and types over the past few decades. To assess the development of vehicular specifications in this context and to evaluate changes in powertrain technologies depending on surrounding frame conditions, such as charging stations and vehicle taxation policy, we need a detailed understanding of the vehicle fleet composition. This paper aims therefore to introduce a novel mathematical approach to segment passenger vehicles based on dimensions features using a means fuzzy clustering algorithm, Fuzzy C-means (FCM), and a non-fuzzy clustering algorithm, K-means (KM). We analyze the performance of the proposed algorithms and compare them with Swiss expert segmentation. Experiments on the real data sets demonstrate that the FCM classifier has better correlation with the expert segmentation than KM. Furthermore, the outputs from FCM with five clusters show that the proposed algorithm has a superior performance for accurate vehicle categorization because of its capacity to recognize and consolidate dimension attributes from the unsupervised data set. Its performance in categorizing vehicles was promising with an average accuracy rate of 79% and an average positive predictive value of 75%.
      Citation: Transportation Research Record
      PubDate: 2021-05-06T12:43:26Z
      DOI: 10.1177/03611981211010795
       
  • Investigation of Surrogate Performance Related Tests for Fatigue Cracking
           of Asphalt Pavements

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      Authors: Liya Jiao, John T. Harvey, Mohamed Elkashef, Yanlong Liang, David Jones
      Abstract: Transportation Research Record, Ahead of Print.
      This paper studies the relationship between laboratory measurements of fatigue performance and fracture performance of conventional asphalt mixtures, asphalt mixtures with reclaimed asphalt pavement (RAP), and rubberized asphalt mixtures. The existing four-point bending (4PB) test was developed to evaluate the fatigue performance of asphalt pavements; however, it is not necessarily appropriate for use in routine job mix formula approval and is too slow and expensive for quality control/quality assurance (QC/QA). In this paper, the semi-circular bending test and indirect tensile asphalt cracking test (IDEAL-CT) were evaluated for their potential to serve as a simple and fast surrogate fatigue performance related test for QC/QA on routine projects and routine mix design. Multiple representative fracture parameters were obtained from the Illinois flexibility index test and the IDEAL-CT. The coefficient of variation revealed that the lowest variability from both tests was in fracture strength. In addition, the linear regression analysis between fracture parameters and fatigue performance indicated that slopes, fracture toughness, and strength from fracture tests have good correlations with the initial flexural stiffness from 4PB tests, while 4PB initial stiffness is well correlated with fatigue life. The direct correlation between fracture properties and fatigue life was not as good. The fracture parameter “strength” also showed the capability of discriminating among asphalt materials with low RAP content.
      Citation: Transportation Research Record
      PubDate: 2021-05-06T12:42:04Z
      DOI: 10.1177/03611981211010182
       
  • Virus Transmission Risk in Urban Rail Systems: Microscopic
           Simulation-Based Analysis of Spatio-Temporal Characteristics

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      Authors: Jiali Zhou, Haris N. Koutsopoulos
      Abstract: Transportation Research Record, Ahead of Print.
      The transmission risk of airborne diseases in public transportation systems is a concern. This paper proposes a modified Wells-Riley model for risk analysis in public transportation systems to capture the passenger flow characteristics, including spatial and temporal patterns, in the number of boarding and alighting passengers, and in number of infectors. The model is used to assess overall risk as a function of origin–destination flows, actual operations, and factors such as mask-wearing and ventilation. The model is integrated with a microscopic simulation model of subway operations (SimMETRO). Using actual data from a subway system, a case study explores the impact of different factors on transmission risk, including mask-wearing, ventilation rates, infectiousness levels of disease, and carrier rates. In general, mask-wearing and ventilation are effective under various demand levels, infectiousness levels, and carrier rates. Mask-wearing is more effective in mitigating risks. Impacts from operations and service frequency are also evaluated, emphasizing the importance of maintaining reliable, frequent operations in lowering transmission risks. Risk spatial patterns are also explored, highlighting locations of higher risk.
      Citation: Transportation Research Record
      PubDate: 2021-05-06T12:41:02Z
      DOI: 10.1177/03611981211010181
       
  • Connected Vehicle-Cooperative Adaptive Cruise Control Algorithm to Divide
           and Reform Connected Vehicle Platoons at Signalized Intersections to
           Improve Traffic Throughput and Safety

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      Authors: Yuwei Bie, Tony Z. Qiu
      Abstract: Transportation Research Record, Ahead of Print.
      The cooperative adaptive cruise control (CACC) algorithm is a simple and effective way to form small-headway platoons so that road capacity and traffic throughput can be improved. The CACC algorithm has been broadly discussed in relation to the highway driving environment where frequent stopping and merging are uncommon. This paper proposes that CACC can also benefit urban arterials, using the appropriate algorithm to predict platoon behavior with optimized trajectories to divide and reform platoons before and after signalized intersections, thus maintaining small, safe headways. Connected vehicle (CV) technology is the key to adapting and improving the CACC algorithm, as it enables the signal phasing plan to be sent to a target CACC platoon and allows vehicles to acquire real-time information from other vehicles in the platoon. In this research, a CV-CACC algorithm is proposed consisting of two functions: platoon division and platoon reforming. The new algorithm is also equipped with acceleration as a new control variable instead of speed, so that the platoon is able to accommodate sharp speed changes around intersections, something the baseline CACC is unable to accommodate. In this study, computer simulations have been conducted to test the reliability of the CV-CACC algorithm and compare its performance against the baseline CACC algorithm.
      Citation: Transportation Research Record
      PubDate: 2021-05-06T12:38:43Z
      DOI: 10.1177/03611981211005456
       
  • Level Crossing Safety Impact Assessments for Vehicle and Pedestrian
           Crossings

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      Authors: Shane Turner, Eddie Cook, Shaun Bosher
      Abstract: Transportation Research Record, Ahead of Print.
      Although the number of deaths and injuries at level crossings in New Zealand is relatively low compared with the national road toll and injury burden, the high severity of crashes involving trains makes it a key “safe system” focus. It is also alarming that the proportion of crashes involving pedestrians and cyclists at level crossings has been increasing over recent years. This in part is owing to the construction of several cycleways and shared paths that travel alongside railway lines. In the past, KiwiRail has relied primarily on the Australian Level Crossing Assessment Model (ALCAM), a crash estimation model, to assess the increased risk of crashes at crossings resulting from a change in use. Although ALCAM is one of the better developed level crossing models internationally, it does have its limitations when used in isolation. ALCAM documentation specifies that other information such as incident data and the opinions of locomotive engineers should be considered in assessing risk. In practice, these factors and ALCAM risk ratings are rarely afforded equal importance. ALCAM does not pick up in sufficient detail the safety impacts created by the surrounding transport network. To better inform decision making, KiwiRail has developed a wider assessment process that includes these factors: the Level Crossing Safety Impact Assessment (LCSIA). This paper outlines the LCSIA process, provides an example of how it has been used, and also discusses the important learnings that have occurred since it was first introduced in 2016.
      Citation: Transportation Research Record
      PubDate: 2021-05-05T12:41:18Z
      DOI: 10.1177/03611981211007857
       
  • Vision for Mechanistic-Empirical Railway Track System and Component
           Analysis and Design

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      Authors: J. Riley Edwards, Ricardo J. Quirós-Orozco, Josué César Bastos, Marcus S. Dersch, Erol Tutumluer
      Abstract: Transportation Research Record, Ahead of Print.
      Many analytical methods and other processes have been developed for the evaluation of railway track and its components, but these have largely been used for analysis. Design is often driven by development projects that do not engage research, resulting in designs that may not be optimized in the context of the broader track structure. This paper proposes a mechanistic-empirical (M-E) analysis and design framework that encourages an understanding of mechanical load-response behavior and comparison of loading demands, and the capacity of the track infrastructure component under study. The approach builds on similar advancements in the field of highway pavement research, including the development and use of the Mechanistic-Empirical Pavement Design Guide (MEPDG). Rail applications present unique economies to a focused M-E design approach, given that loads are concentrated in localized regions and beneath the rails. This paper first reviews prior design and analysis approaches, then presents the essential features of an M-E railway track system and component analysis and design, and, in the end, notes gaps that will require future research before proper implementation of M-E design within rail engineering. The authors also discuss the role of probabilistic design and structural reliability analysis in future design practices. Finally, governing mechanistic failure modes for the track system as well as components and associated life cycle data to achieve full implementation of such an M-E design process are identified and a path forward for implementation is proposed.
      Citation: Transportation Research Record
      PubDate: 2021-05-05T12:39:01Z
      DOI: 10.1177/03611981211009881
       
  • Lane-Change Gaming Decision Control Based on Multiple Targets Evaluation
           for Autonomous Vehicle

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      Authors: Yangyang Wang, Hangyun Deng, Guangda Chen
      Abstract: Transportation Research Record, Ahead of Print.
      Automatic lane change is one of the most important highway operations. It seriously affects traffic efficiency and safety. It is also an important driving technology for automatic driving. To achieve the best automatic lane-change control, it is necessary to achieve the control from the perspective of multi-objective evaluation. In this paper, to make it applicable for a hybrid condition of car following and lane change, the traditional car-following model is modified by regarding the longitudinal motion during the lane-changing process as a transition of the car-following behavior in the two lanes before and after a certain lane-change behavior. A hyperbolic tangent transition function is introduced to connect the model to achieve a smooth transition of the model output. Then, the discretionary lane-change decision process of highway autonomous vehicles is modeled into a two-vehicle game model, and a comprehensive loss function concerning safety, efficiency, and ride comfort is proposed for the evaluation of the strategies. The optimal strategy is obtained by minimizing the expectation of losses. Finally, to verify the performance of the proposed new model, simulations of different car-following and lane-changing models are carried out, which is for multi-target simulation conditions. The results of the simulation show that the new model exhibits higher traffic efficiency, better homogeneity, and stability.
      Citation: Transportation Research Record
      PubDate: 2021-05-03T12:06:35Z
      DOI: 10.1177/03611981211011167
       
  • Assessment of Arterial Signal Timings Based on Various Operational
           Policies and Optimization Tools

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      Authors: Suhaib Al Shayeb, Nemanja Dobrota, Aleksandar Stevanovic, Nikola Mitrovic
      Abstract: Transportation Research Record, Ahead of Print.
      Traffic simulation and optimization tools are classified, according to their practical applicability, into two main categories: theoretical and practical. The performance of the optimized signal timing derived by any tool is influenced by how calculations are executed in the particular tool. Highway Capacity Software (HCS) and Vistro implement the procedures defined in the Highway Capacity Manual, thus they are essentially utilized by traffic operations and design engineers. Considering its capability of timing diagram drafting and travel time collection studies, Tru-Traffic is more commonly used by practitioners. All these programs have different built-in objective function(s) to develop optimized signal plans for intersections. In this study, the performance of the optimal signal timing plans developed by HCS, Tru-Traffic, and Vistro are evaluated and compared by using the microsimulation software Vissim. A real-world urban arterial with 20 intersections and heavy traffic in Fort Lauderdale, Florida served as the testbed. To eliminate any bias in the comparisons, all experiments were performed under identical geometric and traffic conditions, coded in each tool. The evaluation of the optimized plans was conducted based on average delay, number of stops, performance index, travel time, and percentage of arrivals on green. Results indicated that although timings developed in HCS reduced delay, they drastically increased number of stops. Tru-Traffic signal timings, when only offsets are optimized, performed better than timings developed by all of the other tools. Finally, Vistro increased arrivals on green, but it also increased delay. Optimized signal plans were transferred manually from optimization tools to Vissim. Therefore, future research should find methods for automatically transferring optimized plans to Vissim.
      Citation: Transportation Research Record
      PubDate: 2021-05-03T12:04:09Z
      DOI: 10.1177/03611981211011165
       
  • Performance-Based and Evidence-Based Approach to Research Implementation
           at the Georgia Department of Transportation

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      Authors: Binh Bui, Adjo Amekudzi-Kennedy, Russell Clark, Janille Smith-Colin, Stephanie Amoaning-Yankson
      Abstract: Transportation Research Record, Ahead of Print.
      This paper discusses the Georgia Department of Transportation’s (GDOT’s) performance-based and evidence-based approach to research implementation. Transportation agencies in the United States spend hundreds of millions of dollars on research, development, and technology transfer annually. From a performance-based standpoint, agencies will realize higher returns on investment and higher impacts of their research programs as research is implemented more effectively and efficiently. From an evidence-based standpoint, requesting evidence of research implementation as implementation deliverables from the outset of the project requires the project research team and other staff to think through and incorporate in the project plan explicit ways in which the research will be implemented. GDOT’s performance-based approach to research program management treats research implementation as part of an overall asset management business process. This process integrates technical, human, organizational, and external resources to encourage, track, and monitor research implementation activities toward achieving agency strategic objectives, using an evidence-based approach. The paper discusses the adoption of a performance-based and evidence-based process, and a research implementation management tool, and their application in the development of the fiscal year 2018 Annual Research Implementation Report as well as its impact within and beyond the agency. This paper is potentially useful to transportation practitioners and agencies that want to adopt a performance-based and evidence-based approach to augment return on research investment.
      Citation: Transportation Research Record
      PubDate: 2021-05-03T12:02:35Z
      DOI: 10.1177/03611981211005466
       
  • Some New Developments in Two-Way-Stop-Controlled Intersections Procedures
           and Recommendations for a Future Version of the Highway Capacity Manual

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      Authors: Ning Wu, Werner Brilon
      Abstract: Transportation Research Record, Ahead of Print.
      The estimation of capacities and traffic performance at two-way-stop-controlled (TWSC) intersections has been the subject of investigations conducted by many researchers. The results of these investigations are incorporated in highway capacity manuals like the U.S. Highway Capacity Manual (HCM) or the German Handbuch für die Bemessung von Strassen (HBS). Although the underlying methodologies are similar, there are two major differences between the current HBS 2015 and HCM6: (a) the procedure for the impedance factor for movements of rank 4 and (b) the procedure for estimating the capacity of shared short lanes for both minor and major movements. In HBS 2015, new developments are accounted for and the accuracy of capacity and traffic quality estimations significantly improved. In HCM6, these two procedures have not been updated. Therefore, the replacement of the two procedures in HCM6 is recommended. In both HCM6 and HBS 2015, the procedures for calculating delays at shared lanes or shared short lanes are inaccurate and they also should be updated. In most cases, the delays are significantly underestimated. Recently, the authors have developed a new methodology dealing with this problem which can be easily incorporated into future versions of HBS and HCM. In this paper, the theoretical backgrounds of the three new methods are presented and major results are summarized. Compared with HCM6, the advantages of the new developments are highlighted. As a recommendation, three corresponding procedures for estimation of capacity and delay are given for potential use in a future version of HCM.
      Citation: Transportation Research Record
      PubDate: 2021-04-30T07:22:05Z
      DOI: 10.1177/03611981211007844
       
  • Deriving Operational Traffic Signal Performance Measures from Vehicle
           Trajectory Data

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      Authors: Enrique Saldivar-Carranza, Howell Li, Jijo Mathew, Margaret Hunter, James Sturdevant, Darcy M. Bullock
      Abstract: Transportation Research Record, Ahead of Print.
      Operations-oriented traffic signal performance measures are important for identifying the need for retiming to improve traffic signal operations. Currently, most traffic signal performance measures are obtained from high-resolution traffic signal controller event data, which provides information on an intersection-by-intersection basis and requires significant initial capital investment. Over 400 billion vehicle trajectory points are generated each month in the United States. This paper proposes using high-fidelity vehicle trajectory data to produce traffic signal performance measures such as: split failure, downstream blockage, and quality of progression, as well as traditional Highway Capacity Manual level of service. Geo-fences are created at specific signalized intersections to filter vehicle waypoints that lie within the generated boundaries. These waypoints are then converted into trajectories that are relative to the intersection. A case study is presented that summarizes the performance of an eight-intersection corridor with four different timing plans using over 160,000 trajectories and 1.4 million GPS samples collected during weekdays in July 2019 between 5:00 a.m. and 10:00 p.m. The paper concludes by commenting on current probe data penetration rates, indicating that these techniques can be applied to corridors with annual average daily traffic of ~15,000 vehicles per day for the mainline approaches, and discussing cloud-based implementation opportunities.
      Citation: Transportation Research Record
      PubDate: 2021-04-30T07:21:21Z
      DOI: 10.1177/03611981211006725
       
  • Evaluating the Durability of Lime-Stabilized Soil Mixtures using Soil
           Mineralogy and Computational Geochemistry

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      Authors: Pavan Akula, Saureen Rajesh Naik, Dallas N. Little
      Abstract: Transportation Research Record, Ahead of Print.
      Lime stabilization is a common technique used to improve the engineering properties of clayey soils. The process of lime stabilization can be split into two parts. First, the mobilization and crowding of [math] ions or [math]molecules from hydrated lime at net negative surface charge sites on expansive clay colloids. Second, the formation of pozzolanic products including calcium-silicate-hydrate (C-S-H) because of reactions within lime-soil mixtures. The pozzolanic reaction is generally considered to be more durable, while the [math] adsorption has been associated with more easily reversible consistency changes. This study offers a protocol to assess whether the stabilization process is dominated by durable C-S-H (pozzolanic) reactions or a combination of cation exchange and pozzolanic reactions. Expansive clays with plasticity indices>45% from a major highway project in Texas are the focus of lime treatment in this study. The protocol consists of subjecting lime-soil mixtures to a reasonable curing period followed by a rigorous but realistic durability test and investigating the quality and quantity of the pozzolanic reaction product. Mineralogical analyses using quantitative X-ray diffraction (XRD) and thermogravimetric analysis (TGA) indicates the formation of different forms of C-S-H. In addition, geochemical modeling is used to simulate the lime-soil reactions and evaluate the effect of pH on the stability of C-S-H. The results indicate C-S-H with Ca/Si ratio of 0.66 as most the stable form of C-S-H among other forms with Ca/Si ratio ranging from 0.66 to 2.25. The effect of reducing equilibrium pH on C-S-H is also evaluated. A reduction in pH favored dissolution of all forms of C-S-H indicating the need to maintain a pH ≥ 10.
      Citation: Transportation Research Record
      PubDate: 2021-04-30T07:20:44Z
      DOI: 10.1177/03611981211007848
       
  • Reliability-Based Assessment of Potential Risk for Lane-Changing Maneuvers

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      Authors: Yang-Jun Joo, Ho-Chul Park, Seung-Young Kho, Dong-Kyu Kim
      Abstract: Transportation Research Record, Ahead of Print.
      Despite the urgent need for continuous risk assessments during autonomous driving, achieving reliable assessment results is still challenging because of the unpredictable behaviors of adjacent human drivers and the resulting complexity. Such complexity increases particularly during lane changes because several vehicles need to interact with other vehicles. Therefore, this paper proposes a new framework to analyze lane-changing risk on freeways considering the forecastability in adjacent vehicles. Virtual lane-change scenarios are constructed based on historical maneuvers in adjacent vehicles, and the risk of potential lane change is evaluated through the safety evaluation result of the scenario. Adjacent vehicles’ future maneuvers are predicted using a multivariate Bayesian structural time series model, and the forecastability is estimated as the standard error of the predicted values. The failure probability of those lane-changing scenarios is obtained through the first-order reliability method, assuming that failure occurred when any time-to-collision value for adjacent vehicles was less than a threshold at the end of the lane change. This study tested two scenarios with three levels of uncertainty to show the effect of uncertainty on the level of risk. The results showed that the reduced uncertainty allowed a clearer distinction between risky situations. The proposed framework differentiates itself from existing methods by estimating higher risk in an adjacent vehicle’s more significant uncertainties. It is expected that the outcome of this study will be valuable in developing reliable lane-change strategies in autonomous driving.
      Citation: Transportation Research Record
      PubDate: 2021-04-30T07:20:27Z
      DOI: 10.1177/03611981211010800
       
  • Slip Coefficient Testing of ASTM A709 Grade 50CR and Dissimilar Metal
           Bolted Connections

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      Authors: Jason T. Provines, Haddis Abebe
      Abstract: Transportation Research Record, Ahead of Print.
      The purpose of this study was to conduct slip coefficient testing of bolted connections made from ASTM A709 Grade 50CR steel to determine how they fit into the current AASHTO LRFD Bridge Design Specifications surface condition classifications. At this time, Grade 50CR steel is not included in these classifications because it was not being used for bridges when the existing surface condition classifications were developed. The slip coefficient tests in this study were conducted according to the Research Council of Structural Connections. Some test specimens were made up entirely of Grade 50CR steel, while others were dissimilar metal connections, consisting of Grade 50CR steel and either weathering or galvanized steel. Dissimilar metal connections were included in the testing because their use is anticipated in which a bridge girder would be constructed using both Grade 50CR steel and other ASTM A709 bridge steels. Results showed that unblasted Grade 50CR steel has a slip coefficient value of at least 0.30, meeting the current AASHTO Class A surface condition for unblasted steel. Blast-cleaned Grade 50CR steel from either steel shot or garnet media has a slip coefficient value of 0.50, meeting the current AASHTO Class B surface condition for blast-cleaned steel. When dissimilar metal connections are made with Grade 50CR steel, the design slip coefficient value of the connection can be taken as equal to the smaller of the two slip coefficient values being joined.
      Citation: Transportation Research Record
      PubDate: 2021-04-29T10:53:28Z
      DOI: 10.1177/03611981211008890
       
  • Forecasting U.S. Maritime Incidents using the Grey-Markov Model

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      Authors: Fatima Zouhair, Jerome Kerby
      Abstract: Transportation Research Record, Ahead of Print.
      Vessel incidents periodically occur in the waterways of the United States, but some types of commercial vessels have shown a downward trend in the number of incidents in recent years. One of the missions of the United States Coast Guard (USCG) is to develop regulations to mitigate and potentially prevent maritime incidents. In this paper, the USCG gathered data on more than 117,000 incidents that involved U.S.-flag vessels in U.S. waterways for the period 2001 through 2018. We applied the Grey System theory or model and Grey-Markov forecasting model to predict the future number of vessel incidents for four different vessel types from 2019 through 2030. Incident data can vary considerably from year to year and often can be incomplete. The Grey-Markov model, which is a combination of the Grey model and the Markov chain process, is suitable for this purpose because of its predictive ability. From our results, we found that the Grey-Markov model performed exceptionally well and showed the predicted values of the number of incidents to be remarkably similar to the actual values with acceptable mean relative errors ranging from 5.2% to 8.2%. We expect that these results will benefit decision makers in formulating sound policies thereby improving the maritime safety of vessels operating in waterways of the United States.
      Citation: Transportation Research Record
      PubDate: 2021-04-29T10:53:26Z
      DOI: 10.1177/03611981211009219
       
  • Performance of Waterproofing Membranes to Protect Concrete Bridge Decks

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      Authors: Matthew A. Haynes, Erdem Coleri, Ihsan Obaid
      Abstract: Transportation Research Record, Ahead of Print.
      The installation of waterproofing membranes on concrete bridge decks is a commonly used strategy to prevent water on the roadway surface from penetrating into the deck and to reduce the load and freeze–thaw related damage to the bridge deck. Typically, an asphalt layer is paved over the waterproofing membrane to prevent damage from heavy vehicles. The early failure of asphalt pavement overlays on concrete bridge decks with waterproofing membranes has been recognized as a significant issue by several transportation agencies. Potential reasons for the failure of the asphalt overlay were thought to be poor adhesion between the waterproofing membrane and the asphalt wearing course, and the material properties of the asphalt layer. By determining the most effective waterproofing methods and strategies, this research will serve to decrease repair and replacement costs, and increase the service life of asphalt overlays on concrete bridge decks. The main goals of this study are to provide the industry and transportation agencies with better insight into the failure mechanisms of asphalt overlays on concrete bridge decks and to establish field and laboratory experiments to evaluate the performance of these overlays. From the results of this study, a poured waterproofing membrane was recommended as an ideal membrane for use on concrete bridge decks because of its ease of installation, complete impermeability, and high bond strengths between the concrete deck, membrane layers, and asphalt overlay.
      Citation: Transportation Research Record
      PubDate: 2021-04-29T10:52:59Z
      DOI: 10.1177/03611981211009527
       
  • Measuring Instantaneous Resilience of a Highway Bridge Subjected to
           Earthquake Events

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      Authors: S. Hooman Ghasemi, Ji Yun Lee
      Abstract: Transportation Research Record, Ahead of Print.
      Bridges in a road network play a significant role in supporting the flows of people, goods, and freight during an earthquake event and are expected to maintain their functionality following the event. Thus, measuring the capability of a bridge immediately following an earthquake event is critical for understanding the post-earthquake functionalities of transportation networks and supply chain systems involving highway bridges. To this end, this paper proposes a new metric for measuring the resistant capacity of a highway immediately following an earthquake event, which is here called instantaneous resilience. The proposed metric first compares the reliability indices of a bridge before and following an earthquake event to measure the immediate earthquake impact. Although this comparison (i.e., robustness measure in this paper) indicates the remaining strength of the bridge subjected to a given earthquake event, it does not reflect collapse failure modes appropriately. Therefore, the proposed instantaneous-resilience metric combines the robustness measure with the structural redundancy measure to consider various scenarios of load path distribution. The proposed metric is computationally efficient because, in the process, it utilizes a generalized reliability-intensity (R-I) surface of a bridge which can be used to calculate the pre- and post-earthquake reliabilities of any bridge designed based on the American Association of State Highway and Transportation Officials (AASHTO) load and resistance factor design (LRFD). Without developing bridge-specific fragility curves and performing structural analysis of a bridge, the proposed measure enables engineers to make a preliminary assessment of the immediate impact of the earthquake on bridges on a quantitative basis. The step-by-step calculation process of the proposed instantaneous-resilience of a bridge is presented, and its potential use in highway network performance assessment is illustrated with a simple hypothetical network system.
      Citation: Transportation Research Record
      PubDate: 2021-04-29T10:52:41Z
      DOI: 10.1177/03611981211009546
       
  • Investigating Head-On Crash Severity Involving Commercial Motor Vehicles
           in Kentucky

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      Authors: James Smith, Mehdi Hosseinpour, Ryan Mains, Nathanael Hummel, Kirolos Haleem
      Abstract: Transportation Research Record, Ahead of Print.
      This study examines various features affecting the severity associated with commercial motor vehicle (CMV, i.e., large truck and bus) head-on collisions on Kentucky highways. Recent five-year (2015–2019) crash data and variables rarely explored before (e.g., presence of centerline rumble strips, type of passing zone, and terrain type) were collected and prepared using Google Maps. A total of 378 CMV-related head-on collisions were analyzed. The generalized ordered probit (GOP) model was employed to identify the significant factors affecting the severity level resulting from CMV head-on collisions. The model allows the coefficients to vary across the injury severity categories for reliable parameter estimations. From the preliminary investigation, rolling terrains had the highest share of severe CMV head-on crashes (62% and 71% for multilane and two-lane roadways, respectively). The presence of centerline rumble strips could reduce severe crash outcomes along multilane and two-lane facilities. The GOP model identified various significant predictors of minor and severe injuries from CMV head-on crashes. Occupants wearing seatbelt were 39.3% less likely to sustain severe head-on crash injuries. From the roadway characteristics, presence of median cable and concrete barriers could significantly reduce the probability of severe head-on crash injuries, with median cables being more effective. With regard to the driver characteristics, drug impairment and speeding increased the risk of sustaining fatal/serious injuries by 39.5% and 26.4%, respectively. Necessary safety recommendations are proposed to reduce the severity of CMV head-on-related collisions. One example is installing median cable barriers along roadway stretches with a history of head-on CMV-related crashes.
      Citation: Transportation Research Record
      PubDate: 2021-04-28T09:13:34Z
      DOI: 10.1177/03611981211010803
       
  • Effect of Changing a Traffic Control Device Color on Driver Behavior and
           Perception across Different Age Groups

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      Authors: Hatem Abou-Senna, Mohamed El-Agroudy, Mustapha Mouloua, Essam Radwan
      Abstract: Transportation Research Record, Ahead of Print.
      The use of express lanes (ELs) in freeway traffic management has seen increasing popularity throughout the United States, particularly in Florida. These lanes aim at making the most efficient transportation system management and operations tool to provide a more reliable trip. An important component of ELs is the channelizing devices used to delineate the separation between the ELs and the general-purpose lane. With the upcoming changes to the FHWA Manual on Uniform Traffic Control Devices, this study provided an opportunity to recommend changes affecting safety and efficiency on a nationwide level. It was important to understand the impacts on driver perception and performance in response to the color of the EL delineators. It was also valuable to understand the differences between demographics in responding to delineator colors under different driving conditions. The driving simulator was used to test the responses of several demographic groups to changes in marker color and driving conditions. Furthermore, participants were tested for several factors relevant to driving performance including visual and subjective responses to the changes in colors and driving conditions. Impacts on driver perception were observed via eye-tracking technology with changes to time of day, visibility, traffic density, roadway surface type, and, crucially, color of the delineating devices. The analyses concluded that white was the optimal and most significant color for notice of delineators across the majority of subjective and performance measures, followed by yellow, with black being the least desirable.
      Citation: Transportation Research Record
      PubDate: 2021-04-28T09:10:41Z
      DOI: 10.1177/03611981211011168
       
  • Measuring Pedestrian Level of Stress in Urban Environments: Naturalistic
           Walking Pilot Study

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      Authors: Seth LaJeunesse, Paul Ryus, Wesley Kumfer, Sirisha Kothuri, Krista Nordback
      Abstract: Transportation Research Record, Ahead of Print.
      Walking is the most basic and sustainable mode of transportation, and many jurisdictions would like to see increased walking rates as a way of reducing congestion and emission levels and improving public health. In the United States, walking trips account for 10.5% of all trips undertaken. To increase this rate, additional research on what makes people feel more comfortable while walking is needed. Research on pedestrian quality of service (QOS) has sought to quantify the performance of the pedestrian facilities from a pedestrian’s perspective. However, the impact of pedestrian safety countermeasures on pedestrian QOS for roadway crossings is largely unknown. The objective of this study is to discern pedestrian QOS based on physiological measurements of pedestrians performing normal walking activities in different traffic contexts. The naturalistic walking study described in this paper recruited 15 pedestrians and asked each to wear an instrumented wristband and GPS recorder on all walking trips for one week. Surprisingly, the findings from the study showed no correlation between participants’ stress levels and individual crossing locations. Instead, stress was associated with roadway conditions. Higher levels of stress were generally associated with walking in proximity to collector and arterial streets and in areas with industrial and mixed (e.g., offices, retail, residential) land uses. Stress levels were tempered in lower-density residential land uses, as well as in forest, park, and university campus environments. The outcomes from this study can inform how planners design urban environments that reduce pedestrian stress levels to promote walkability.
      Citation: Transportation Research Record
      PubDate: 2021-04-28T09:08:41Z
      DOI: 10.1177/03611981211010183
       
  • Examining Driver Injury Severity in Single-Vehicle Road Departure Crashes
           Involving Large Trucks

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      Authors: Mehdi Hosseinpour, Kirolos Haleem
      Abstract: Transportation Research Record, Ahead of Print.
      Road departure (RD) crashes are among the most severe crashes that can result in fatal or serious injuries, especially when involving large trucks. Most previous studies neglected to incorporate both roadside and median hazards into large-truck RD crash severity analysis. The objective of this study was to identify the significant factors affecting driver injury severity in single-vehicle RD crashes involving large trucks. A random-parameters ordered probit (RPOP) model was developed using extensive crash data collected on roadways in the state of Kentucky between 2015 and 2019. The RPOP model results showed that the effect of local roadways, the natural logarithm of annual average daily traffic (AADT), the presence of median concrete barriers, cable barrier-involved collisions, and dry surfaces were found to be random across the crash observations. The results also showed that older drivers, ejected drivers, and drivers trapped in their truck were more likely to sustain severe single-vehicle RD crashes. Other variables increasing the probability of driver injury severity have included rural areas, dry road surfaces, higher speed limits, single-unit truck types, principal arterials, overturning-consequences, truck fire occurrence, segments with median concrete barriers, and roadside fixed object strikes. On the other hand, wearing seatbelt, local roads and minor collectors, higher AADT, and hitting median cable barriers were associated with lower injury severities. Potential safety countermeasures from the study findings include installing median cable barriers and flattening steep roadside embankments along those roadway stretches with high history of RD large-truck-related crashes.
      Citation: Transportation Research Record
      PubDate: 2021-04-28T09:06:41Z
      DOI: 10.1177/03611981211010178
       
  • Factors Affecting Driver Injury Severity in the Wrong-Way Crash:
           Accounting for Potential Heterogeneity in Means and Variances of Random
           Parameters

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      Authors: Miao Yu, Jinxing Shen, Changxi Ma
      Abstract: Transportation Research Record, Ahead of Print.
      Because of the high percentage of fatalities and severe injuries in wrong-way driving (WWD) crashes, numerous studies have focused on identifying contributing factors to the occurrence of WWD crashes. However, a limited number of research effort has investigated the factors associated with driver injury-severity in WWD crashes. This study intends to bridge the gap using a random parameter logit model with heterogeneity in means and variances approach that can account for the unobserved heterogeneity in the data set. Police-reported crash data collected from 2014 to 2017 in North Carolina are used. Four injury-severity levels are defined: fatal injury, severe injury, possible injury, and no injury. Explanatory variables, including driver characteristics, roadway characteristics, environmental characteristics, and crash characteristics, are used. Estimation results demonstrate that factors, including the involvement of alcohol, rural area, principal arterial, high speed limit (>60 mph), dark-lighted conditions, run-off-road collision, and head-on collision, significantly increase the severity levels in WWD crashes. Several policy implications are designed and recommended based on findings.
      Citation: Transportation Research Record
      PubDate: 2021-04-28T09:05:01Z
      DOI: 10.1177/03611981211009882
       
  • Assessment of Commercial Truck Driver Injury Severity as a Result of
           Driving Actions

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      Authors: Muhammad Tahmidul Haq, Milan Zlatkovic, Khaled Ksaibati
      Abstract: Transportation Research Record, Ahead of Print.
      The disaggregate modeling approach is a new trend in the literature to analyze the injury severity of truck-involved crashes. The assessment of truck driver injury severity based on driver action is still missing in the literature. This paper presents an extensive exploratory analysis that highlights significant variability in the severity of truck drivers’ injuries based on various action types (i.e., aggressive driving, failure to keep proper lane, driving too fast, and no improper driving). Binary logistic regression with the Bayesian random intercept approach was developed to examine the factors contributing to fatal or any injuries of truck drivers using 10 years (2007–2016) of historical crash data in Wyoming. Log-likelihood ratio tests were performed to justify that separate models by various driving action types are warranted. The results demonstrated the effects of various vehicle, driver, crash, and roadway characteristics, combined with truck driver-specific action, on the corresponding severity of driver injury. The gross vehicle weight, age and gender of the driver, time of day, lighting condition, and the presence of junctions were found to have significantly different impacts on the severity of truck driver injury in various driving action-related crashes. With the incorporation of the random intercept in the modeling procedure, the analysis found a strong presence (27%–33%) of intra-crash correlation in driver injury severity within the same crash. Finally, based on the findings of this study, several recommendations are made.
      Citation: Transportation Research Record
      PubDate: 2021-04-28T09:02:41Z
      DOI: 10.1177/03611981211009880
       
  • Field Density Investigation of Asphalt Mixtures in Minnesota

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      Authors: Tianhao Yan, Mihai Marasteanu, Chelsea Bennett, John Garrity
      Abstract: Transportation Research Record, Ahead of Print.
      In a current research effort, University of Minnesota and Minnesota Department of Transportation have been working on designing asphalt mixtures that can be constructed at 5% air voids, similar to the Superpave 5 mix design. High field density of asphalt mixtures is desired because it increases the durability and extends the service life of asphalt pavements. The paper investigates the current situation of field densities in Minnesota, to better understand how much improvement is needed from the current field density level to the desired level, and to identify possible changes to the current mix design to improve field compactability. Field densities and material properties of 15 recently constructed projects in Minnesota are investigated. First, a statistical analysis is performed to study the probability distribution of field densities. Then, a two-way analysis of variance is conducted to check if the nominal maximum aggregate size and traffic levels have any significant effect on field densities. A correlation analysis is then conducted to identify significant correlations between the compactability of mixtures and their material properties. The results show that the field density data approximately obey normal distribution, with an average field density of 93.4% of theoretical maximum specific gravity; there are significant differences in field density between mixtures with different traffic levels; compactability of mixtures is significantly correlated with fine aggregate angularity and fine aggregate gradation of the mixtures.
      Citation: Transportation Research Record
      PubDate: 2021-04-28T09:00:20Z
      DOI: 10.1177/03611981211009545
       
  • Development of a Novel Intelligent Speed Adaptation System Based on
           Available Sight Distance

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      Authors: Abrar Hazoor, Alessandra Lioi, Marco Bassani
      Abstract: Transportation Research Record, Ahead of Print.
      Most existing roads were designed without considering the improved performance of modern vehicles and the new onboard technologies available for assisted driving. In addition, vehicles frequently travel at speeds that exceed the maximum considered in road design. For these reasons, the need for speed- and safety-related countermeasures (e.g., field control, mobile or fixed speed cameras, traffic calming measures) is evident. However, these countermeasures are only partially effective and the proportion of crashes that are speed-related remains significant. This investigation is aimed at the development of a new intelligent speed adaptation (ISA) system based on the available sight distance (ASD). In conditions of poor visibility, the system can (i) inform drivers when they are traveling at inappropriate speeds, or (ii) generate warning sounds to the same effect, or (iii) intervene directly and compel the vehicle to adopt the speed which is most appropriate to the particular ASD. As reported in this methodological paper, the functionality of the new ISA system was tested at the driving simulator of the Politecnico di Torino (Italy) and the resulting estimated ASD value was validated and tested successfully. Future experimental investigations will be devoted to assessing the effectiveness of the system on driver speed behavior and decision making.
      Citation: Transportation Research Record
      PubDate: 2021-04-28T08:57:53Z
      DOI: 10.1177/03611981211008885
       
  • Cable Median Barrier Effect on Commercial Vehicle Crossover Crashes

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      Authors: Nikiforos Stamatiadis, Shraddha Sagar, Samantha Wright, Eric Green, Reginald Souleyrette
      Abstract: Transportation Research Record, Ahead of Print.
      In the United States (U.S.) the annual number of commercial motor vehicle (CMV) crashes has been on an upward trajectory since 2009. In 2016, CMV crashes accounted for 11.8% of all fatal crashes in the U.S., and in Kentucky, between 2009 and 2016, the number of CMV crashes rose 27%. Of particular concern to state departments of transportation have been crossover crashes involving CMVs. These occur when a vehicle leaves its intended path and veers into the path of oncoming traffic, typically resulting in head-on or sideswipe opposite direction collisions. While some researchers have found that installing cable median barriers can mitigate crossover crashes involving CMVs, no definitive conclusions have been reached. To move toward a resolution of this question, this study leveraged analysis by a panel of experts and the development of safety performance functions and crash modification factors to gauge how cable median barriers can influence the number and severity of crossover CMV crashes on Kentucky interstate routes. Expert panelists contended that cable median barriers will improve safety, a conclusion substantiated by statistical modeling. Despite the study’s limited scope, it appears that installing cable median barriers can prevent or mitigate CMV crashes.
      Citation: Transportation Research Record
      PubDate: 2021-04-28T08:56:10Z
      DOI: 10.1177/03611981211007845
       
  • Driving Maneuvers Detection using Semi-Supervised Long Short-Term Memory
           and Smartphone Sensors

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      Authors: Pei Li, Mohamed Abdel-Aty, Zubayer Islam
      Abstract: Transportation Research Record, Ahead of Print.
      Driving maneuvers detection is an important component of proactive traffic safety management and connected vehicle systems. Most of the existing studies used supervised learning concepts to train their models with labeled data. These methods achieved promising results but were limited by the heavy dependence on the labeled data. With the development of mobile sensing technologies, massive traffic-related data can be efficiently collected by mobile devices (e.g., smartphones, tablets, etc.). Considering the high costs of labeling data, this paper proposed a semi-supervised deep learning method to learn from the unlabeled data. Data from a smartphone’s accelerometer and gyroscope were collected by different drivers with a variety of smartphones, vehicles, and locations. Three long short-term memory (LSTM) models were trained with the proposed semi-supervised learning algorithm. Experimental results indicated that the proposed semi-supervised LSTM could learn from the unlabeled data and achieve outstanding results with only a small portion of the labeled data. Using much fewer labeled data, semi-supervised LSTM could achieve similar results compared with the supervised method. Moreover, the proposed method outperformed other machine learning methods (e.g., convolutional neural network, XGBoost, random forest) on precision, recall, F1-score, and area under curve. More and more traffic data will be available in the future, the proposed method is expected to make use of the undiscovered potential from the massive unlabeled data.
      Citation: Transportation Research Record
      PubDate: 2021-04-28T08:53:34Z
      DOI: 10.1177/03611981211007483
       
  • Automated Detection and Classification of Pavement Distresses using 3D
           Pavement Surface Images and Deep Learning

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      Authors: Rohit Ghosh, Omar Smadi
      Abstract: Transportation Research Record, Ahead of Print.
      Pavement distresses lead to pavement deterioration and failure. Accurate identification and classification of distresses helps agencies evaluate the condition of their pavement infrastructure and assists in decision-making processes on pavement maintenance and rehabilitation. The state of the art is automated pavement distress detection using vision-based methods. This study implements two deep learning techniques, Faster Region-based Convolutional Neural Networks (R-CNN) and You Only Look Once (YOLO) v3, for automated distress detection and classification of high resolution (1,800 × 1,200) three-dimensional (3D) asphalt and concrete pavement images. The training and validation dataset contained 625 images that included distresses manually annotated with bounding boxes representing the location and types of distresses and 798 no-distress images. Data augmentation was performed to enable more balanced representation of class labels and prevent overfitting. YOLO and Faster R-CNN achieved 89.8% and 89.6% accuracy respectively. Precision-recall curves were used to determine the average precision (AP), which is the area under the precision-recall curve. The AP values for YOLO and Faster R-CNN were 90.2% and 89.2% respectively, indicating strong performance for both models. Receiver operating characteristic (ROC) curves were also developed to determine the area under the curve, and the resulting area under the curve values of 0.96 for YOLO and 0.95 for Faster R-CNN also indicate robust performance. Finally, the models were evaluated by developing confusion matrices comparing our proposed model with manual quality assurance and quality control (QA/QC) results performed on automated pavement data. A very high level of match to manual QA/QC, namely 97.6% for YOLO and 96.9% for Faster R-CNN, suggest the proposed methodology has potential as a replacement for manual QA/QC.
      Citation: Transportation Research Record
      PubDate: 2021-04-28T08:50:33Z
      DOI: 10.1177/03611981211007481
       
  • Modeling CO2 Emissions from Trips using Urban Air Mobility and Emerging
           Automobile Technologies

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      Authors: Sai V. Mudumba, Hsun Chao, Apoorv Maheshwari, Daniel A. DeLaurentis, William A. Crossley
      Abstract: Transportation Research Record, Ahead of Print.
      Urban air mobility (UAM) operations provide the potential for more, or more attractive, trips in a metropolitan area relative to wholly surface-based transportation. But the emissions produced by a UAM mode must be studied in relation to these benefits. In this paper, an emissions model for the UAM context using electric vertical takeoff and landing (eVTOL) aircraft is developed that incorporates CO2 gases emitted from the electricity production required to charge the vehicle batteries. The model quantifies trip emissions using UAM for part or all of the trip and compares these with automobile-based trips. The estimations consider using gasoline and electric automobiles, with the impact of autonomy and average ground speeds in traffic. Trip case studies in the Chicago and Dallas metropolitan areas showcase the regional differences when using UAM and different automobile technology scenarios. In particular, differences stemming from how electricity generation from power grids (i.e., grid emission index) contributes to CO2 emissions of eVTOL trips and electric automobile trips in the Chicago and Dallas metropolitan areas are computed. This paper introduces trip properties called the surface-to-air distance ratio and the detour ratio to understand how they influence the CO2 emissions of a trip. Results from the simulation on identified trip cases in Chicago and Dallas illustrate the significant impact of the grid emission index of a region’s power plant on the emissions of electric vehicles.
      Citation: Transportation Research Record
      PubDate: 2021-04-28T08:47:35Z
      DOI: 10.1177/03611981211006439
       
  • Comparing Regional Sustainability and Transportation Sustainability at the
           Metropolitan Level in the U.S. using Artificial Neural Network Clustering
           Techniques

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      Authors: Haiqing Liu, Na Chen, Xinhao Wang
      Abstract: Transportation Research Record, Ahead of Print.
      Regional sustainability and transportation sustainability have been intensely discussed and analyzed in recent decades. Though the use of indicators has been adopted in those models, debates continue on what indicators should be used and how to optimize the number of indicators. This results in the lack of a comprehensive and efficient method to assess and compare the sustainability of a sub-system, such as transportation system, and overall regional sustainability. A thorough literature review is conducted to identify indicators used to assess regional sustainability and transportation sustainability. Then, based on the available data, two sets of indicators for regional sustainability and transportation sustainability are identified and calculated respectively for the 382 metropolitan statistical areas (MSAs) in the U.S. A self-organizing map, which is a type of artificial neural network, is used to cluster the MSAs and compare their regional sustainability and transportation sustainability as well as to investigate the relationships among indicators. The results show that MSAs with a higher score on regional sustainability do not necessarily have a higher score on transportation sustainability. Some MSAs that are geographically close to each other have similar scores in regional sustainability and transportation sustainability. These findings provide insights to decision makers that the assessment of sustainability should consider both correlation and heterogeneity of different indicators within a region. Therefore, it is important to develop a comprehensive and efficient method to evaluate the role of sustainability in one urban sub-system, such as transportation, in the overall regional sustainability.
      Citation: Transportation Research Record
      PubDate: 2021-04-27T07:56:42Z
      DOI: 10.1177/03611981211009519
       
  • Meso-Scale Kinematic Responses of Asphalt Mixture in Both Field and
           Laboratory Compaction

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      Authors: Xue Wang, Shihui Shen, Hai Huang
      Abstract: Transportation Research Record, Ahead of Print.
      Compaction is one of the most critical steps in asphalt pavement construction. Traditional compaction relies heavily on engineering experience and post-construction quality control and can lead to under/over compaction problems. The emerging intelligent compaction technology has improved compaction quality but is still not successful in obtaining mixture properties of a single pavement layer. Besides, very few studies have discussed the internal material responses during field and laboratory compaction to explain the meso-scale (i.e., particle scale) compaction mechanism. Knowledge in those areas may greatly promote the development of smart compaction. Therefore, this study aims to investigate the kinematic behavior of the asphalt mixture particles (translation and rotation) under six types of field and laboratory compaction methods and establish the relationship between the field and the laboratory compaction by using a real-time particle motion sensor, SmartRock. It was found that particle movement pattern was mainly affected by the compaction mode. At the meso-scale where particle behavior is the focus, the kneading effects of a pneumatic-tire roller can be simulated by laboratory gyratory and rolling wheel compaction, and the vibrating effects of a vibratory roller can be simulated by Marshall compaction. However, none of those laboratory compaction methods can completely simulate the field compaction. Under vibratory rolling, particle acceleration decreased fast in the breakdown rolling stage. Under pneumatic-tire rolling, particle angular position change was related to aggregate skeleton, and particle relative rotation showed a decreasing trend that was consistent with the laboratory gyratory compaction results. Those kinematic responses can potentially be used to monitor density change in field compaction.
      Citation: Transportation Research Record
      PubDate: 2021-04-27T07:54:10Z
      DOI: 10.1177/03611981211009222
       
  • Use of the Pavement Surface Cracking Metric to Quantify Distresses from
           Digital Images

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      Authors: Danilo Balzarini, James Erskine, Michael Nieminen
      Abstract: Transportation Research Record, Ahead of Print.
      The development of new laser technologies in recent years has changed pavement data collection, opening the door to a fully automated approach. In this paper the application of the Pavement Surface Cracking Metric (PSCM), inspired by the Universal Cracking Indicator proposed by William Paterson in 1994, and developed by the ASTM E17 group is presented. The method uses quantitative definitions to ensure consistency of the results and eliminate the subjectivity associated with human ratings of pavement distresses. Multiple runs of pavement data have been collected on three asphalt sections to assess the repeatability and reproducibility of the method. The application of the Pavement Surface Cracking Index to convert the PSCM value, which is a physical property of the pavement, into a 100-0 score of the pavement section is also presented. Finally, the use of the PSCM to classify pavement distress and the inclusion of potholes and patching in the metrics are discussed.
      Citation: Transportation Research Record
      PubDate: 2021-04-27T07:53:12Z
      DOI: 10.1177/03611981211008189
       
  • Effectiveness of Green Warning Lights with Different Flashing Patterns for
           Winter Maintenance Operations

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      Authors: Fatemeh Fakhrmoosavi, Ramin Saedi, Farish Jazlan, Ali Zockaie, Mehrnaz Ghamami, Timothy J. Gates, Peter T. Savolainen
      Abstract: Transportation Research Record, Ahead of Print.
      Snow removal activities are performed by roadway agencies to enhance winter mobility and safety. Slower travel speeds during these operations, combined with low visibility and reduced pavement friction, mean that safety and collision avoidance remain a persistent concern. Many studies have implemented signing and lighting technologies to improve the visibility of snowplows. Although a few studies have evaluated the use of different colors on snowplows, there is no rigorous study that evaluates the potential impacts of using green warning lights for winter maintenance operations. This study, therefore, investigates the impacts of various warning light configurations on the visibility of snowplows, with the focus on green lights. To this end, 37 warning light configurations are designed using various color combinations (green and amber), and flashing patterns (single and quad) on the back (LED), the top (beacon), or both, of snowplows. These configurations are evaluated to identify the most effective configurations. Three sets of experiments are designed and implemented: static, dynamic, and weather to evaluate the visibility effectiveness in different contexts: day versus night, clear versus snowy weather, and static versus dynamic scenarios. Human subjects are employed to conduct the experiments and the test results are evaluated using statistical analyses. The conspicuity during the day time and glare during the night time are statistically different among various configurations. In addition, adding green lights with a single flash pattern to amber warning lights improves the conspicuity, while keeping the glare at an acceptable level relative to configurations using only amber.
      Citation: Transportation Research Record
      PubDate: 2021-04-27T07:52:10Z
      DOI: 10.1177/03611981211008187