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  Subjects -> TRANSPORTATION (Total: 151 journals)
    - AIR TRANSPORT (6 journals)
    - AUTOMOBILES (20 journals)
    - RAILROADS (4 journals)
    - ROADS AND TRAFFIC (4 journals)
    - SHIPS AND SHIPPING (25 journals)
    - TRANSPORTATION (92 journals)

TRANSPORTATION (92 journals)

Accident Analysis & Prevention     Partially Free   (Followers: 19)
AI & Society     Hybrid Journal   (Followers: 2)
Archives of Transport     Open Access   (Followers: 4)
Bitácora Urbano-Territorial     Open Access   (Followers: 2)
Botswana Journal of Technology     Full-text available via subscription  
Cities in the 21st Century     Open Access   (Followers: 11)
Economics of Transportation     Partially Free   (Followers: 10)
Emission Control Science and Technology     Hybrid Journal  
EURO Journal of Transportation and Logistics     Hybrid Journal   (Followers: 4)
European Transport Research Review     Open Access   (Followers: 10)
Geosystem Engineering     Hybrid Journal   (Followers: 3)
IATSS Research     Open Access  
IEEE Vehicular Technology Magazine     Full-text available via subscription   (Followers: 5)
IET Electrical Systems in Transportation     Hybrid Journal   (Followers: 6)
IET Intelligent Transport Systems     Hybrid Journal   (Followers: 4)
International Innovation – Transport     Open Access   (Followers: 3)
International Journal of Applied Logistics     Full-text available via subscription   (Followers: 5)
International Journal of Crashworthiness     Hybrid Journal   (Followers: 4)
International Journal of Critical Infrastructure Protection     Hybrid Journal   (Followers: 5)
International Journal of Electric and Hybrid Vehicles     Hybrid Journal   (Followers: 5)
International Journal of Electronic Transport     Hybrid Journal   (Followers: 2)
International Journal of Heavy Vehicle Systems     Hybrid Journal   (Followers: 6)
International Journal of Intelligent Transportation Systems Research     Hybrid Journal   (Followers: 5)
International Journal of Micro-Nano Scale Transport     Full-text available via subscription   (Followers: 2)
International Journal of Mobile Communications     Hybrid Journal   (Followers: 7)
International Journal of Ocean Systems Management     Hybrid Journal   (Followers: 3)
International Journal of Physical Distribution & Logistics Management     Hybrid Journal   (Followers: 8)
International Journal of Services Technology and Management     Hybrid Journal   (Followers: 1)
International Journal of Sustainable Transportation     Hybrid Journal   (Followers: 5)
International Journal of Traffic and Transportation Engineering     Open Access   (Followers: 14)
International Journal of Transportation Science and Technology     Full-text available via subscription   (Followers: 5)
International Journal of Vehicle Systems Modelling and Testing     Hybrid Journal   (Followers: 4)
International Journal of Vehicular Technology     Open Access   (Followers: 2)
Journal of Advanced Transportation     Hybrid Journal   (Followers: 11)
Journal of Modern Transportation     Full-text available via subscription   (Followers: 1)
Journal of Navigation     Hybrid Journal   (Followers: 83)
Journal of Sport & Social Issues     Hybrid Journal   (Followers: 9)
Journal of Sustainable Mobility     Full-text available via subscription  
Journal of the Transportation Research Forum     Open Access   (Followers: 4)
Journal of Transport & Health     Hybrid Journal   (Followers: 2)
Journal of Transport and Land Use     Open Access   (Followers: 12)
Journal of Transport and Supply Chain Management     Open Access   (Followers: 6)
Journal of Transport Geography     Hybrid Journal   (Followers: 16)
Journal of Transport History     Full-text available via subscription   (Followers: 10)
Journal of Transport Literature     Open Access  
Journal of Transportation Safety & Security     Hybrid Journal   (Followers: 8)
Journal of Transportation Security     Hybrid Journal   (Followers: 2)
Journal of Transportation Systems Engineering and Information Technology     Full-text available via subscription   (Followers: 14)
Journal of Transportation Technologies     Open Access   (Followers: 11)
Journal of Waterway Port Coastal and Ocean Engineering     Full-text available via subscription   (Followers: 7)
Les Dossiers du Grihl     Open Access  
Logistique & Management     Full-text available via subscription  
Mechatronics, Electrical Power, and Vehicular Technology     Open Access   (Followers: 1)
Modern Transportation     Open Access   (Followers: 2)
Nonlinear Dynamics     Hybrid Journal   (Followers: 5)
Open Journal of Safety Science and Technology     Open Access   (Followers: 5)
Pervasive and Mobile Computing     Hybrid Journal   (Followers: 9)
Proceedings of the Institution of Mechanical Engineers Part F: Journal of Rail and Rapid Transit     Hybrid Journal   (Followers: 5)
PS: Political Science & Politics     Full-text available via subscription   (Followers: 22)
Public Transport     Hybrid Journal   (Followers: 8)
Recherche Transports Sécurité     Hybrid Journal   (Followers: 1)
Research in Transportation Business and Management     Partially Free   (Followers: 2)
Revista Transporte y Territorio     Open Access   (Followers: 1)
SourceOCDE Transports     Full-text available via subscription   (Followers: 1)
Sport, Education and Society     Hybrid Journal   (Followers: 11)
Sport, Ethics and Philosophy     Hybrid Journal   (Followers: 2)
Streetnotes     Open Access   (Followers: 3)
Synthesis Lectures on Mobile and Pervasive Computing     Full-text available via subscription   (Followers: 2)
Tire Science and Technology     Full-text available via subscription  
Transactions on Transport Sciences     Open Access   (Followers: 3)
Transport     Hybrid Journal   (Followers: 6)
Transport and Telecommunication Journal     Open Access   (Followers: 2)
Transport in Porous Media     Hybrid Journal   (Followers: 1)
Transport Reviews: A Transnational Transdisciplinary Journal     Hybrid Journal   (Followers: 6)
Transportation     Hybrid Journal   (Followers: 18)
Transportation Geotechnics     Full-text available via subscription  
Transportation Infrastructure Geotechnology     Hybrid Journal   (Followers: 6)
Transportation Journal     Full-text available via subscription   (Followers: 5)
Transportation Research Part A: Policy and Practice     Hybrid Journal   (Followers: 25)
Transportation Research Part B: Methodological     Hybrid Journal   (Followers: 23)
Transportation Research Part C: Emerging Technologies     Hybrid Journal   (Followers: 15)
Transportation Research Record : Journal of the Transportation Research Board     Full-text available via subscription   (Followers: 29)
Transportation Science     Full-text available via subscription   (Followers: 14)
TRANSPORTES     Open Access   (Followers: 2)
Transportmetrica A : Transport Science     Hybrid Journal   (Followers: 1)
Transportmetrica B : Transport Dynamics     Hybrid Journal  
Travel Behaviour and Society     Full-text available via subscription  
Travel Medicine and Infectious Disease     Hybrid Journal   (Followers: 2)
Urban, Planning and Transport Research     Open Access   (Followers: 3)
Vehicular Communications     Full-text available via subscription  
World Review of Intermodal Transportation Research     Hybrid Journal   (Followers: 3)
Транспортні системи та технології перевезень     Open Access  
Journal Cover   Transportation Research Part C: Emerging Technologies
  [SJR: 1.943]   [H-I: 55]   [17 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0968-090X
   Published by Elsevier Homepage  [2588 journals]
  • Overview of missing physical commodity trade data and its imputation using
           data augmentation
    • Abstract: Publication date: May 2015
      Source:Transportation Research Part C: Emerging Technologies, Volume 54
      Author(s): J. Farhan
      The physical aspects of commodity trade are becoming increasingly important on a global scale for transportation planning, demand management for transportation facilities and services, energy use, and environmental concerns. Such aspects (for example, weight and volume) of commodities are vital for logistics industry to allow for medium-to-long term planning at the strategic level and identify commodity flow trends. However, incomplete physical commodity trade databases impede proper analysis of trade flow between various countries. The missing physical values could be due to many reasons such as, (1) non-compliance of reporter countries with the prescribed regulations by World Customs Organization (WCO) (2) confidentiality issues, (3) delays in processing of data, or (4) erroneous reporting. The traditional missing data imputation methods, such as the substitution by mean, substitution by linear interpolation/extrapolation using adjacent points, the substitution by regression, and the substitution by stochastic regression, have been proposed in the context of estimating physical aspects of commodity trade data. However, a major demerit of these single imputation methods is their failure to incorporate uncertainty associated with missing data. The use of computationally complex stochastic methods to improve the accuracy of imputed data has recently become possible with the advancement of computer technology. Therefore, this study proposes a sophisticated data augmentation algorithm in order to impute missing physical commodity trade data. The key advantage of the proposed approach lies in the fact that instead of using a point estimate as the imputed value, it simulates a distribution of missing data through multiple imputations to reflect uncertainty and to maintain variability in the data. This approach also provides the flexibility to include fundamental distributional property of the variables, such as physical quantity, monetary value, price elasticity of demand, price variation, and product differentiation, and their correlations to generate reasonable average estimates of statistical inferences. An overview and limitations of most commonly used data imputation approaches is presented, followed by the theoretical basis and imputation procedure of the proposed approach. Lastly, a case study is presented to demonstrate the merits of the proposed approach in comparison to traditional imputation methods.


      PubDate: 2015-03-18T18:46:21Z
       
  • A multi-path progression model for synchronization of arterial traffic
           signals
    • Abstract: Publication date: April 2015
      Source:Transportation Research Part C: Emerging Technologies, Volume 53
      Author(s): Xianfeng Yang , Yao Cheng , Gang-Len Chang
      To contend with congestion and spillback on commuting arterials, serving as connectors between freeway and surface-street flows, this paper presents three multi-path progression models to offer progression bands for multiple critical path-flows contributing to the high volume in each arterial link. The first proposed model is a direct extension of MAXBAND under a predetermined phasing plan, but using the path-flow data to yield the progression bands. The second model further takes the phase sequence at each intersection as a decision variable, and concurrently optimizes the signal plans with offsets for the entire arterial. Due to the competing nature of multi-path progression flows over the same green duration, the third model is proposed with a function to automatically select the optimal number of paths in their bandwidths maximization process. The results of extensive simulation studies have shown that the proposed models outperform conventional design methods, such as MAXBAND or TRANSYT, especially for those arterials with multiple heavy path-flows. The research results from this study have also reflected the need to collect more traffic pattern data such as major path-flow volumes, in addition to the typical intersection volume counts.


      PubDate: 2015-03-15T07:13:36Z
       
  • An ontological model to support communications of situation-aware vehicles
    • Abstract: Publication date: April 2015
      Source:Transportation Research Part C: Emerging Technologies, Volume 53
      Author(s): Seong Kyu Choi
      In an Intelligent Transport System (ITS) environment, the communication component is of great importance to support interactions between vehicles and roadside infrastructure. Previous studies have focused on the physical capability and capacity of the communication technologies, but the equally important development of suitable and efficient semantic content for transmission received notably less attention. Ontology is one promising approach for context modelling in ubiquitous computing environments, and in the transport domain it can be used both for context modelling and semantic contents for vehicular communications. This paper explores the development of an ontological model implementing relative geo-semantic information messages to support vehicle-to-vehicle communications. The proposed ontology model contains classes, objects, their properties/relations as well as some functions and query templates to represent and update the information of dynamic vehicles, inter-vehicle interactions and behaviour. This model was developed through a scenario enabling the evaluation of traffic conflict resolution approaches, by implementing a set of decision-making processes for intelligent vehicles. Given the scope of the proposed ontology modelling, it shows how vehicular communications can be used to update each vehicle’s context model. This work can be easily extended for more complex interactions among vehicles and the infrastructure.


      PubDate: 2015-03-15T07:13:36Z
       
  • Pedestrian traffic management of boarding and alighting in metro stations
    • Abstract: Publication date: April 2015
      Source:Transportation Research Part C: Emerging Technologies, Volume 53
      Author(s): Sebastian Seriani , Rodrigo Fernandez
      The objective of this work is to determine, by means of simulation and experiments, the effect of pedestrian traffic management in the boarding and alighting time of passengers at metro stations. Studies were made by means of a pedestrian traffic microsimulator (LEGION Studio) and experiments at the Human Dynamic Laboratory (HDL) of Universidad de los Andes in Santiago de Chile, to obtain criteria for the pedestrian traffic management on the platform and doors of metro cars. The methodology consists of building a boarding/alighting hall of a metro car and the relevant portion of the platform in front of the hall. The simulation scenarios included the location of the vertical handrail in the hall of the car, delimitation of a keep out zone in front of the doors and the use of differentiated doors for boarding and alighting. The results of the simulation and laboratory experiments are expressed in Pedestrian Level of Service (LOS), Passenger Service Time (PST), passenger density on the vehicle and platform, and passenger dissatisfaction. Both, the simulation results and laboratory experiments allow us to give some recommendations for the pedestrian traffic management in metro systems.


      PubDate: 2015-03-15T07:13:36Z
       
  • The impact of real-time information on bus ridership in New York City
    • Abstract: Publication date: April 2015
      Source:Transportation Research Part C: Emerging Technologies, Volume 53
      Author(s): Candace Brakewood , Gregory S. Macfarlane , Kari Watkins
      In the past few years, numerous mobile applications have made it possible for public transit passengers to find routes and/or learn about the expected arrival time of their transit vehicles. Though these services are widely used, their impact on overall transit ridership remains unclear. The objective of this research is to assess the effect of real-time information provided via web-enabled and mobile devices on public transit ridership. An empirical evaluation is conducted for New York City, which is the setting of a natural experiment in which a real-time bus tracking system was gradually launched on a borough-by-borough basis beginning in 2011. Panel regression techniques are used to evaluate bus ridership over a three year period, while controlling for changes in transit service, fares, local socioeconomic conditions, weather, and other factors. A fixed effects model of average weekday unlinked bus trips per month reveals an increase of approximately 118 trips per route per weekday (median increase of 1.7% of weekday route-level ridership) attributable to providing real-time information. Further refinement of the fixed effects model suggests that this ridership increase may only be occurring on larger routes; specifically, the largest quartile of routes defined by revenue miles of service realized approximately 340 additional trips per route per weekday (median increase of 2.3% per route). Although the increase in weekday route-level ridership may appear modest, on aggregate these increases exert a substantial positive effect on farebox revenue. The implications of this research are critical to decision-makers at the country’s transit operators who face pressure to increase ridership under limited budgets, particularly as they seek to prioritize investments in infrastructure, service offerings, and new technologies.


      PubDate: 2015-03-15T07:13:36Z
       
  • A network level connectivity robustness measure for connected vehicle
           environments
    • Abstract: Publication date: April 2015
      Source:Transportation Research Part C: Emerging Technologies, Volume 53
      Author(s): Osama A. Osman , Sherif Ishak
      This study introduces a new CONnectivity ROBustness model (CONROB) to assess vehicle-to-vehicle communication in connected vehicle (CV) environments. CONROB is based on Newton’s universal law of gravitation and accounts for multiple factors affecting the connectivity in CV environments such as market penetration, wireless transmission range, spatial distribution of vehicles relative to each other, the spatial propagation of the wireless signal, and traffic density. The proposed methodology for the connectivity robustness calculation in CONROB accounts for the Link Expiration Time (LET) and the Route Expiration Time (RET) that are reflected in the stability of links between each two adjacent vehicles and the expiration time of communication routes between vehicles. Using a 117sq-km (45-square mile) network in Washington County, located west of Portland city, Oregon, a microscopic simulation model (VISSIM) was built to verify CONROB model. A total of 45 scenarios were simulated for different traffic densities generated from five different traffic demand levels, three levels of market penetration (5%, 15%, and 25%), and three transmission range values [76 (250), 152 (500), and 305 (1000)m (ft)]. The simulation results show that the overall robustness increases as the market penetration increases, given the same transmission range, and relative traffic density. Similarly, the overall connectivity robustness increases as the relative traffic density increases for the same market penetration. More so, the connectivity robustness becomes more sensitive to the relative traffic density at higher values of transmission range and market penetration. Multiple regression analysis was conducted to show the significant effect of relative traffic density, transmission range, and market penetration on the robustness measure. The results of the study provide an evidence of the ability of the model to capture the effect of the different factors on the connectivity between vehicles, which provides a viable tool for assessing CV environments.


      PubDate: 2015-03-15T07:13:36Z
       
  • Instantaneous communication throughputs of vehicular ad hoc networks
    • Abstract: Publication date: April 2015
      Source:Transportation Research Part C: Emerging Technologies, Volume 53
      Author(s): Hao Yang , Wen-Long Jin
      Vehicular ad hoc networks (VANETs) formed by connected vehicles in a traffic stream could be applied to improve safety, mobility, and environmental impacts of a transportation system. In this paper, we present analytical models for the instantaneous communication throughputs of VANETs to measure the efficiency of information propagation under various traffic conditions at a time instant. In particular, we define broadcast and unicast communication throughputs by the wireless channel bandwith multiplied by the average probabilities that one vehicle is a successful receiver and sender in a VAENT, respectively. With a protocol communication model, we derive formulas to determine the probabilities for an equipped vehicle to be a successful broadcast receiver and a successful unicast receiver/sender, and obtain broadcast and unicast throughputs along discrete and continuous traffic streams. We further examine the impacts on communication throughputs of the transmission range and the interference range of dedicated short range communication devices as well as the market penetration rate of equipped vehicles and the percentage of senders. Finally, we investigate the influence of shock waves on communication throughputs.


      PubDate: 2015-03-15T07:13:36Z
       
  • Locating fixed roadside units in a bus transport network for maximum
           communications probability
    • Abstract: Publication date: April 2015
      Source:Transportation Research Part C: Emerging Technologies, Volume 53
      Author(s): Miguel Rios , Vladimir Marianov , Melisa Pérez
      A key issue in solving the difficult bus-bunching problem is being able to have reliable information about the location of the buses in the network. Most advanced public transport systems have buses with GPS devices, but the problem remains of how to send reliable information from the buses to the control unit, particularly when the density of buses is low, but there are high communications reliability requirements. As a solution, we study locating roadside units (RSUs) along the route. The buses, together with the RSUs, form a linear vehicular ad-hoc network (VANET). The RSUs are deployed so to maximize the probability of a vehicle communicating with an RSU in at most two hops. Previous studies on RSU location never took into account two hops, a conceptually different type of network. Rather, they consider that a vehicle is able to communicate only directly to an RSU (one hop), which is a well-known Maximum Covering Problem, in which one of the parties is always immobile, similar to a mobile phone network. Oppositely, our method solves the problem in which two of the intervening parties are mobile and communicate with each other, not possible to solve as a Maximum Covering Problem. We estimate the probability of a vehicle accessing successfully an RSU either directly or through the relay of another vehicle. This probability is later embedded in an integer programming formulation that optimizes the RSU locations for maximum communications likelihood. Numerical examples show that the connection probability is strongly dependent on the coverage ratio of the transmitters and receivers and relatively independent on the vehicle density on the network, when densities are low. Results also show that it is possible to find some cost-efficient solutions which result in a smaller number of RSUs located while assuring a connection probability of 0.9 or higher.


      PubDate: 2015-03-15T07:13:36Z
       
  • Point-to-point speed enforcement systems: Speed limits design criteria and
           analysis of drivers’ compliance
    • Abstract: Publication date: April 2015
      Source:Transportation Research Part C: Emerging Technologies, Volume 53
      Author(s): Alfonso Montella , Vincenzo Punzo , Salvatore Chiaradonna , Filomena Mauriello , Marcello Montanino
      Point-to-point (P2P) speed enforcement is a relatively new approach to traffic law enforcement. Its technology allows vehicles whose average speed exceeds the speed limit over the controlled section to be fined. It therefore encourages compliance over distances longer than those where spot enforcement policies have been in place. In this paper, a procedure for consistently setting speed limits with such enforcement systems is proposed. Such a method has been applied to design the speed limits on two motorways in the district of Naples, Italy, where P2P enforcement systems became operational in 2009 and 2010. The speed limits, which were set using the Italian geometric design standard to assess vehicle stability and stopping sight distance, have been compared with those provided by using well-known international standards. The impact of the newly designed speed limits and of the P2P enforcement system on drivers’ speeding behaviour has been quantified for each highway section and vehicle type. In fact, accurate measurements of the average travel speeds of each vehicle crossing the enforced sections, before and after the activation of the system, were available. The migration from the old speed limits with spot speed enforcement to the new approach resulted in a notable increase in drivers’ compliance to the speed limits with a remarkable decrease in both the average of individual speeds and in their standard deviation. In addition, the analysis of 3years of data shows that a gradual adaptation of drivers’ behaviour to the system took place. In particular, a decreasing compliance to the speed limits points to a non-optimal system management. Finally, the results of a revealed preference survey allowed us to make a behavioural interpretation regarding the significantly different impacts measured on the two motorways.


      PubDate: 2015-03-15T07:13:36Z
       
  • Estimation of flow and density using probe vehicles with spacing
           measurement equipment
    • Abstract: Publication date: April 2015
      Source:Transportation Research Part C: Emerging Technologies, Volume 53
      Author(s): Toru Seo , Takahiko Kusakabe , Yasuo Asakura
      Probe vehicles provide some of the most useful data for road traffic monitoring because they can acquire wide-ranging and spatiotemporally detailed information at a relatively low cost compared with traditional fixed-point observation. However, current GPS-equipped probe vehicles cannot directly provide us volume-related variables such as flow and density. In this paper, we propose a new probe vehicle-based estimation method for obtaining volume-related variables by assuming that a probe vehicle can measure the spacing to its leading one. This assumption can be realized by utilizing key technologies in advanced driver assistance systems that are expected to spread in the near future. We developed a method of estimating the flow, density, and speed from the probe vehicle data without exogenous assumptions on traffic flow characteristics, such as a fundamental diagram. In order to quantify the characteristics of the method, we performed a field experiment at a real-world urban expressway by employing prototypes of the probe vehicles with spacing measurement equipment. The result showed that the proposed method could accurately estimate the 5min and hourly traffic volumes with probe vehicle penetration rate of 3.5% and 0.2%, respectively.


      PubDate: 2015-03-15T07:13:36Z
       
  • A hybrid heuristic strategy for liquefied natural gas inventory routing
    • Abstract: Publication date: April 2015
      Source:Transportation Research Part C: Emerging Technologies, Volume 53
      Author(s): Yufen Shao , Kevin C. Furman , Vikas Goel , Samid Hoda
      As liquefied natural gas (LNG) steadily grows to be a common mode for commercializing natural gas, LNG supply chain optimization is becoming a key technology for gas companies to maintain competitiveness. This paper develops methods for improving the solutions for a previously stated form of an LNG inventory routing problem (LNG-IRP). Motivated by the poor performance of a Dantzig-Wolfe-based decomposition approach for exact solutions, we develop a suite of advanced heuristic techniques and propose a hybrid heuristic strategy aiming to achieve improved solutions in shorter computational time. The heuristics include two phases: the advanced construction phase is based on a rolling time algorithm and a greedy randomized adaptive search procedure (GRASP); and the solution improvement phase is a series of novel MIP-based neighborhood search techniques. The proposed algorithms are evaluated based on a set of realistic large-scale instances seen in recent literature. Extensive computational results indicate that the hybrid heuristic strategy is able to obtain optimal or near optimal feasible solutions substantially faster than commercial optimization software and also the previously proposed heuristic methods.


      PubDate: 2015-03-15T07:13:36Z
       
  • Big Data applications in real-time traffic operation and safety monitoring
           and improvement on urban expressways
    • Abstract: Publication date: Available online 12 March 2015
      Source:Transportation Research Part C: Emerging Technologies
      Author(s): Qi Shi , Mohamed Abdel-Aty
      The advent of Big Data era has transformed the outlook of numerous fields in science and engineering. The transportation arena also has great expectations of taking the advantage of Big Data enabled by the popularization of Intelligent Transportation Systems (ITS). In this study, the viability of a proactive real-time traffic monitoring strategy evaluating operation and safety simultaneously was explored. The objective is to improve the system performance of urban expressways by reducing congestion and crash risk. In particular, Microwave Vehicle Detection System (MVDS) deployed on an expressway network in Orlando was utilized to achieve the objectives. The system consisting of 275 detectors covers 75 miles of the expressway network, with average spacing less than 1 mile. Comprehensive traffic flow parameters per lane are continuously archived on one-minute interval basis. The scale of the network, dense deployment of detection system, richness of information and continuous collection turn MVDS as the ideal source of Big Data. It was found that congestion on urban expressways was highly localized and time-specific. As expected, the morning and evening peak hours were the most congested time periods. The results of congestion evaluation encouraged real-time safety analysis to unveil the effects of traffic dynamics on crash occurrence. Data mining (random forest) and Bayesian inference techniques were implemented in real-time crash prediction models. The identified effects, both indirect (peak hour, higher volume and lower speed upstream of crash locations) and direct (higher congestion index downstream to crash locations) congestion indicators confirmed the significant impact of congestion on rear-end crash likelihood. As a response, reliability analysis was introduced to determine the appropriate time to trigger safety warnings according to the congestion intensity. Findings of this paper demonstrate the importance to jointly monitor and improve traffic operation and safety. The Big Data generated by the ITS systems is worth further exploration to bring all their full potential for more proactive traffic management.


      PubDate: 2015-03-15T07:13:36Z
       
  • Weather impact on containership routing in closed seas: A
           chance-constraint optimization approach
    • Abstract: Publication date: Available online 11 March 2015
      Source:Transportation Research Part C: Emerging Technologies
      Author(s): Konstantinos Kepaptsoglou , Grigorios Fountas , Matthew G. Karlaftis
      Weather conditions have a strong effect on the operation of vessels and unavoidably influence total time at sea and associated transportation costs. The velocity and direction of the wind in particular may considerably affect travel speed of vessels and therefore the reliability of scheduled maritime services. This paper considers weather effects in containership routing; a stochastic model is developed for determining optimal routes for a homogeneous fleet performing pick-ups and deliveries of containers between a hub and several spoke ports, while incorporating travel time uncertainties attributed to the weather. The problem is originally formulated as a chance-constrained variant of the vehicle routing problem with simultaneous pick-ups and deliveries and time constraints and solved using a genetic algorithm. The model is implemented to a network of island ports of the Aegean Sea. Results on the application of algorithm reveal that a small fleet is sufficient enough to serve network’s islands, under the influence of minor delays. A sensitivity analysis based on alternative scenarios in the problem’s parameters, leads to encouraging conclusions with respect to the efficiency and robustness of the algorithm.


      PubDate: 2015-03-15T07:13:36Z
       
  • Origin–destination trips by purpose and time of day inferred from
           mobile phone data
    • Abstract: Publication date: Available online 9 March 2015
      Source:Transportation Research Part C: Emerging Technologies
      Author(s): Lauren Alexander , Shan Jiang , Mikel Murga , Marta C. González
      In this work, we present methods to estimate average daily origin–destination trips from triangulated mobile phone records of millions of anonymized users. These records are first converted into clustered locations at which users engage in activities for an observed duration. These locations are inferred to be home, work, or other depending on observation frequency, day of week, and time of day, and represent a user’s origins and destinations. Since the arrival time and duration at these locations reflect the observed (based on phone usage) rather than true arrival time and duration of a user, we probabilistically infer departure time using survey data on trips in major US cities. Trips are then constructed for each user between two consecutive observations in a day. These trips are multiplied by expansion factors based on the population of a user’s home Census Tract and divided by the number of days on which we observed the user, distilling average daily trips. Aggregating individuals’ daily trips by Census Tract pair, hour of the day, and trip purpose results in trip matrices that form the basis for much of the analysis and modeling that inform transportation planning and investments. The applicability of the proposed methodology is supported by validation against the temporal and spatial distributions of trips reported in local and national surveys.


      PubDate: 2015-03-15T07:13:36Z
       
  • Towards data-driven car-following models
    • Abstract: Publication date: Available online 7 March 2015
      Source:Transportation Research Part C: Emerging Technologies
      Author(s): Vasileia Papathanasopoulou , Constantinos Antoniou
      Car following models have been studied with many diverse approaches for decades. Nowadays, technological advances have significantly improved our traffic data collection capabilities. Conventional car following models rely on mathematical formulas and are derived from traffic flow theory; a property that often makes them more restrictive. On the other hand, data-driven approaches are more flexible and allow the incorporation of additional information to the model; however, they may not provide as much insight into traffic flow theory as the traditional models. In this research, an innovative methodological framework based on a data-driven approach is proposed for the estimation of car-following models, suitable for incorporation into microscopic traffic simulation models. An existing technique, i.e. locally weighted regression (loess), is defined through an optimization problem and is employed in a novel way. The proposed methodology is demonstrated using data collected from a sequence of instrumented vehicles in Naples, Italy. Gipps’ model, one of the most extensively used car-following models, is calibrated against the same data and used as a reference benchmark. Optimization issues are raised in both cases. The obtained results suggest that data-driven car-following models could be a promising research direction.


      PubDate: 2015-03-15T07:13:36Z
       
  • Network design for personal rapid transit under transit-oriented
           development
    • Abstract: Publication date: Available online 7 March 2015
      Source:Transportation Research Part C: Emerging Technologies
      Author(s): Hong Zheng , Srinivas Peeta
      This study addresses guideway network design for personal rapid transit (PRT) favoring transit-oriented development. The guideway network design problem seeks to minimize both the guideway construction cost and users’ travel time. In particular, a set of optional points, known as Steiner points, are introduced in the graph to reduce the guideway length. The model is formulated as a combined Steiner and assignment problem, and a Lagrangian relaxation based solution algorithm is developed to solve the optimal solution. Numerical studies are carried on a real-sized network, and illustrate that the proposed model and solution algorithm can solve the PRT guideway network design problem effectively.


      PubDate: 2015-03-15T07:13:36Z
       
  • Optimality versus run time for isolated signalized intersections
    • Abstract: Publication date: Available online 7 March 2015
      Source:Transportation Research Part C: Emerging Technologies
      Author(s): David K. Hale , Byungkyu Brian Park , Aleksandar Stevanovic , Peng Su , Jiaqi Ma
      Simulation-based optimization of traffic signal timing has become pervasive and popular, in the field of traffic engineering. When the underlying simulation model is well-trusted and/or well-calibrated, it is only natural that typical engineers would want their signal timing optimized using the judgment of that same model. As such, it becomes important that the heuristic search methods typically used by these optimizations are capable of locating global optimum solutions, for a wide range of signal systems. However off-line and real-time solutions alike offer just a subset of the available search methods. The result is that many optimizations are likely converging prematurely on mediocre solutions. In response, this paper compares several search methods from the literature, in terms of both optimality (i.e., solution quality) and computer run times. Simulated annealing and genetic algorithm methods were equally effective in achieving near-global optimum solutions. Two selection methods (roulette wheel and tournament), commonly used within genetic algorithms, exhibited similar effectiveness. Tabu searching did not provide significant benefits. Trajectories of optimality versus run time (OVERT) were similar for each method, except some methods aborted early along the same trajectory. Hill-climbing searches always aborted early, even with a large number of step-sizes. Other methods only aborted early when applied with ineffective parameter settings (e.g. mutation rate, annealing schedule). These findings imply (1) today’s products encourage a sub-optimal “one size fits all” approach, (2) heuristic search methods and parameters should be carefully selected based on the system being optimized, (3) weaker searches abort early along the OVERT curve, and (4) improper choice of methods and/or parameters can reduce optimization benefits by 22–33%.


      PubDate: 2015-03-15T07:13:36Z
       
  • A utility-maximization model for retrieving users’ willingness to
           travel for participating in activities from big-data
    • Abstract: Publication date: Available online 5 March 2015
      Source:Transportation Research Part C: Emerging Technologies
      Author(s): Konstantinos Gkiotsalitis , Antony Stathopoulos
      Dense cities with complex transport infrastructure and numerous Places of Interest (POIs) pose challenges to interpersonal interactions since the location and the time of conducting a joint activity are rarely agreed unanimously from all agents, mainly due to lack of information of each agent’s schedule and activity preferences. In this paper, a utility maximization model for capturing automatically users’ willingness to travel a certain distance for participating in different activity types based on user-generated data is introduced. The model is based on Big-Data analytics on user-generated data from Social Media that can offer valuable insights into users’ preferences and improve our understanding on their decision-making mechanisms for selecting joint activities. Unlike static approaches, the utility model of each agent is developed to incorporate continuously updated data feeds regarding agents’ activities (i.e., timing of visiting a POI, type of POI). The agent-utility model is implemented and tested via utilizing geo-tagged, social media data from 65 individuals from the dense city of London (crawling campaign from November 2012–January 2014). After implementing the utility-maximization model, all users are clustered based on their willingness to travel similar distances to participate in certain types of activities, facilitating the development of applications for suggesting joint activities among agents with similar profiles.


      PubDate: 2015-03-15T07:13:36Z
       
  • An optimization method for sustainable traffic control in urban areas
    • Abstract: Publication date: Available online 5 March 2015
      Source:Transportation Research Part C: Emerging Technologies
      Author(s): Eleni Papatzikou , Antony Stathopoulos
      The optimization of traffic signalization in urban areas is formulated as a problem of finding the cycle length, the green times and the offset of traffic signals that minimize an objective function of performance indices. Typical approaches to this optimization problem include the maximization of traffic throughput or the minimization of vehicles’ delays, number of stops, fuel consumption, etc. Dynamic Traffic Assignment (DTA) models are widely used for online and offline applications for efficient deployment of traffic control strategies and the evaluation of traffic management schemes and policies. We propose an optimization method for combining dynamic traffic assignment and network control by minimizing the risk of potential loss induced to travelers by exceeding their budgeted travel time as a result of deployed traffic signal settings, using the Conditional Value-at-Risk model. The proposed methodology can be easily implemented by researchers or practitioners to evaluate their alternative strategies and aid them to choose the alternative with less potential risk. The traffic signal optimization procedure is implemented in TRANSYT-7F and the dynamic propagation and route choice of vehicles is simulated with a mesoscopic dynamic traffic assignment tool (DTALite) with fixed temporal demand and network characteristics. The proposed approach is applied to a reference test network used by many researchers for verification purposes. Numerical experiments provide evidence of the advantages of this optimization method with respect to conventional optimization techniques. The overall benefit to the performance of the network is evaluated with a Conditional Value-at-Risk Analysis where the optimal solution is the one presenting the least risk for ‘guaranteed’ total travel times.


      PubDate: 2015-03-15T07:13:36Z
       
  • Editorial Board/Copyright Information
    • Abstract: Publication date: March 2015
      Source:Transportation Research Part C: Emerging Technologies, Volume 52




      PubDate: 2015-03-15T07:13:36Z
       
  • Autonomous cars: The tension between occupant experience and intersection
           capacity
    • Abstract: Publication date: March 2015
      Source:Transportation Research Part C: Emerging Technologies, Volume 52
      Author(s): Scott Le Vine , Alireza Zolfaghari , John Polak
      Systems that enable high levels of vehicle-automation are now beginning to enter the commercial marketplace. Road vehicles capable of operating independently of real-time human control under an increasing set of circumstances will likely become more widely available in the near future. Such vehicles are expected to bring a variety of benefits. Two such anticipated advantages (relative to human-driver vehicle control) are said to be increased road network capacity and the freeing up of the driver-occupant’s time to engage in their choice of leisurely or economically-productive (non-driving) tasks. In this study we investigate the implications for intersection capacity and level-of-service of providing occupants of automated (without real-time human control), autonomously-operating (without vehicle-to-X communication) cars with ride quality that is equivalent (in terms of maximum rates of longitudinal and lateral acceleration) to two types of rail systems: [urban] light rail transit and [inter-urban] high-speed rail. The literature suggests that car passengers start experiencing discomfort at lower rates of acceleration than car drivers; it is therefore plausible that occupants of an autonomously-operating vehicle may wish to instruct their vehicle to maneuver in a way that provides them greater ride comfort than if the vehicle-control algorithm simply mimicked human-driving-operation. On the basis of traffic microsimulation analysis, we found that restricting the dynamics of autonomous cars to the acceleration/deceleration characteristics of both rail systems leads to reductions in a signalized intersection’s vehicle-processing capacity and increases in delay. The impacts were found to be larger when constraining the autonomous cars’ dynamics to the more-restrictive acceleration/deceleration profile of high-speed rail. The scenarios we analyzed must be viewed as boundary conditions, because autonomous cars’ dynamics were by definition never allowed to exceed the acceleration/deceleration constraints of the rail systems. Appropriate evidence regarding motorists’ preferences does not exist at present; establishing these preferences is an important item for the future research agenda. This paper concludes with a brief discussion of research needs to advance this line of inquiry.


      PubDate: 2015-03-15T07:13:36Z
       
  • A stochastic optimization model for transit network timetable design to
           mitigate the randomness of traveling time by adding slack time
    • Abstract: Publication date: March 2015
      Source:Transportation Research Part C: Emerging Technologies, Volume 52
      Author(s): Yinghui Wu , Jiafu Tang , Yang Yu , Zhendong Pan
      Transit network timetabling aims at determining the departure time of each trip of all lines in order to facilitate passengers transferring either to or from a bus. In this paper, we consider a bus timetabling problem with stochastic travel times (BTP-STT). Slack time is added into timetable to mitigate the randomness in bus travel times. We then develop a stochastic integer programming model for the BTP-STT to minimize the total waiting time cost for three types of passengers (i.e., transferring passengers, boarding passengers and through passengers). The mathematical properties of the model are characterized. Due to its computational complexity, a genetic algorithm with local search (GALS) is designed to solve our proposed model (OPM). The numerical results based on a small bus network show that the timetable obtained from OPM reduces the total waiting time cost by an average of 9.5%, when it is tested in different scenarios. OPM is relatively effective if the ratio of the number of through passengers to the number of transferring passengers is not larger than a threshold (e.g., 10 in our case). In addition, we test different scale instances randomly generated in a practical setting to further verify the effectiveness of OPM and GALS. We also find that adding slack time into timetable greatly benefits transferring passengers by reducing the rate of transferring failure.


      PubDate: 2015-03-15T07:13:36Z
       
  • Second-order models and traffic data from mobile sensors
    • Abstract: Publication date: March 2015
      Source:Transportation Research Part C: Emerging Technologies, Volume 52
      Author(s): Benedetto Piccoli , Ke Han , Terry L. Friesz , Tao Yao , Junqing Tang
      Mobile sensing enabled by GPS or smart phones has become an increasingly important source of traffic data. For sufficient coverage of the traffic stream, it is important to maintain a reasonable penetration rate of probe vehicles. From the standpoint of capturing higher-order traffic quantities such as acceleration/deceleration, emission and fuel consumption rates, it is desirable to examine the impact on the estimation accuracy of sampling frequency on vehicle position. Of the two issues raised above, the latter is rarely studied in the literature. This paper addresses the impact of both sampling frequency and penetration rate on mobile sensing of highway traffic. To capture inhomogeneous driving conditions and deviation of traffic from the equilibrium state, we employ the second-order phase transition model (PTM). Several data fusion schemes that incorporate vehicle trajectory data into the PTM are proposed. And, a case study of the NGSIM dataset is presented which shows the estimation results of various Eulerian and Lagrangian traffic quantities. The findings show that while first-order traffic quantities can be accurately estimated even with a low sampling frequency, higher-order traffic quantities, such as acceleration, deviation, and emission rate, tend to be misinterpreted due to insufficiently sampled vehicle locations. We also show that a correction factor approach has the potential to reduce the sensing error arising from low sampling frequency and penetration rate, making the estimation of higher-order quantities more robust against insufficient data coverage of the highway traffic.


      PubDate: 2015-03-15T07:13:36Z
       
  • Maritime routing and speed optimization with emission control areas
    • Abstract: Publication date: March 2015
      Source:Transportation Research Part C: Emerging Technologies, Volume 52
      Author(s): Kjetil Fagerholt , Nora T. Gausel , Jørgen G. Rakke , Harilaos N. Psaraftis
      Strict limits on the maximum sulphur content in fuel used by ships have recently been imposed in some Emission Control Areas (ECAs). In order to comply with these regulations many ship operators will switch to more expensive low-sulphur fuel when sailing inside ECAs. Since they are concerned about minimizing their costs, it is likely that speed and routing decisions will change because of this. In this paper, we develop an optimization model to be applied by ship operators for determining sailing paths and speeds that minimize operating costs for a ship along a given sequence of ports. We perform a computational study on a number of realistic shipping routes in order to evaluate possible impacts on sailing paths and speeds, and hence fuel consumption and costs, from the ECA regulations. Moreover, the aim is to examine the implications for the society with regards to environmental effects. Comparisons of cases show that a likely effect of the regulations is that ship operators will often choose to sail longer distances to avoid sailing time within ECAs. Another effect is that they will sail at lower speeds within and higher speeds outside the ECAs in order to use less of the more expensive fuel. On some shipping routes, this might give a considerable increase in the total amount of fuel consumed and the CO2 emissions.


      PubDate: 2015-03-15T07:13:36Z
       
  • A stochastic fleet size and mix model for maintenance operations at
           offshore wind farms
    • Abstract: Publication date: March 2015
      Source:Transportation Research Part C: Emerging Technologies, Volume 52
      Author(s): Christian Gundegjerde , Ina B. Halvorsen , Elin E. Halvorsen-Weare , Lars Magnus Hvattum , Lars Magne Nonås
      A fleet of vessels and helicopters is needed to support maintenance operations at offshore wind farms. The cost of this fleet constitutes a major part of the total maintenance costs, hence keeping an optimal or near-optimal fleet is essential to reduce the cost of energy. In this paper we study the vessel fleet size and mix problem that arises for the maintenance operations at offshore wind farms, and propose a stochastic three-stage programming model. The stochastic model considers uncertainty in vessel spot rates, weather conditions, electricity prices and failures to the system. The model is tested on realistic-sized problem instances, and the results show that it is valuable to consider uncertainty and that the proposed model can be used to solve instances of a realistic size.


      PubDate: 2015-03-15T07:13:36Z
       
  • Vehicle-to-vehicle connectivity on parallel roadways with large road
           separation
    • Abstract: Publication date: March 2015
      Source:Transportation Research Part C: Emerging Technologies, Volume 52
      Author(s): Xiubin Bruce Wang , Kai Yin , Xuedong Yan
      This paper studies vehicle multihop connectivity of vehicular ad hoc networks (VANETs) on two parallel roads. It complements our earlier studies by considering a road separation distance larger than 3 2 L and considering signal blockage between roads, where L represents the transmission range. Assuming vehicles follow Poisson processes, we specifically derive exact formulas for the expectation, variance, and probability distribution of the information propagation distance. We further develop a closed form approximation for the expected distance. The analytical results are verified and compared with those from other headway distributions of varying coefficient of variation through Monte Carlo simulation.


      PubDate: 2015-03-15T07:13:36Z
       
  • Use of magnetic monitoring of vehicles for proactive strategy development
    • Abstract: Publication date: March 2015
      Source:Transportation Research Part C: Emerging Technologies, Volume 52
      Author(s): Szymon Gontarz , Przemysław Szulim , Jarosław Seńko , Jacek Dybała
      The proactive operational strategy in the transport system which is a parallel concept associated with the Intelligent Transportation System (ITS) seems to be modern and right direction of development. However, the basis for its operation is the “information” in the broad sense of the term, on the functioning of the transport system itself. As new technologies develop, there emerge new opportunities of putting to use a wide array of sensors which can deliver more complete traffic data but using complex matrix of sensors is often unjustified economically and confusing. The paper proposes use of magnetometers as an interesting alternative to pass the requirements of simplicity of application, minimum costs and maximum of acquired information. The process of obtaining the information requires analysis of the quantitative and qualitative changes of the magnetic field. The conducted analyses demonstrate the possibility of using the passive magnetic methods for the purpose of monitoring of vehicles. Placement of the magnetic sensor bear out an important issue and was also discussed. During the experimental research it has been proven that passive magnetic methods enable obtaining the information on the movement of a vehicle as well as on the vehicle itself. Estimations of such values as: vehicle’s moving direction, velocity, dimensions, clearance or mass having ferromagnetic properties and even the state of strain in a vehicle’s structure were confirmed in practice. In addition thanks to magneto-mechanical effects the theoretical possibility of assessing the stress occurring in the components of vehicles, which could be indicative of the volume of cargo carried. Moreover, the crash experiment showed the possibility of a collision detection using magnetic signal. The need for obtaining information increases from year to year, with information becoming the biggest asset which enables both development and effective use of the transport system. Included researches, proofs emerging opportunity of more extensive use of magnetic sensors and the passive magnetic methods which could be applied in the modern transportation system.


      PubDate: 2015-03-15T07:13:36Z
       
  • An integrated Bayesian approach for passenger flow assignment in metro
           networks
    • Abstract: Publication date: March 2015
      Source:Transportation Research Part C: Emerging Technologies, Volume 52
      Author(s): Lijun Sun , Yang Lu , Jian Gang Jin , Der-Horng Lee , Kay W. Axhausen
      This paper proposes an integrated Bayesian statistical inference framework to characterize passenger flow assignment model in a complex metro network. In doing so, we combine network cost attribute estimation and passenger route choice modeling using Bayesian inference. We build the posterior density by taking the likelihood of observing passenger travel times provided by smart card data and our prior knowledge about the studied metro network. Given the high-dimensional nature of parameters in this framework, we apply the variable-at-a-time Metropolis sampling algorithm to estimate the mean and Bayesian confidence interval for each parameter in turn. As a numerical example, this integrated approach is applied on the metro network in Singapore. Our result shows that link travel time exhibits a considerable coefficient of variation about 0.17, suggesting that travel time reliability is of high importance to metro operation. The estimation of route choice parameters conforms with previous survey-based studies, showing that the disutility of transfer time is about twice of that of in-vehicle travel time in Singapore metro system.


      PubDate: 2015-03-15T07:13:36Z
       
  • The container retrieval problem with respect to relocation
    • Abstract: Publication date: March 2015
      Source:Transportation Research Part C: Emerging Technologies, Volume 52
      Author(s): Dung-Ying Lin , Yen-Ju Lee , Yusin Lee
      The demand for container terminal yards is growing significantly faster than the supply of available land; therefore, containers are typically stacked high to better utilize the land space in container yards. However, in the process of container retrieval, non-productive reshuffling may be required to relocate the containers that are stacked on top of the target container. Container retrieval is directly related to the operational efficiency of terminals. Because the industry has become increasingly competitive, it has become critical to introduce a systematic approach to retrieving containers. In this study, we develop a heuristic that can generate feasible working plans for rail-mounted gantry cranes (RMGC) in container yards to minimize the number of container movements while taking the RMGC working time into consideration. The methodology takes into consideration the case that containers are grouped in terms of their retrieval order. Multi-lift RMGC models also are studied. Comprehensive numerical experiments reveal that the method runs faster than other methods published in the literature by several orders of magnitude; additionally, our method is able to solve instances larger than practical use. The number of movements approaches a theoretical lower bound, and the numerical results clearly demonstrate the tradeoff between the number of movements and the working time, and provide useful insights for yard planning.


      PubDate: 2015-03-15T07:13:36Z
       
  • An optimization framework for workplace charging strategies
    • Abstract: Publication date: March 2015
      Source:Transportation Research Part C: Emerging Technologies, Volume 52
      Author(s): Yongxi Huang , Yan Zhou
      The workplace charging (WPC) has been recently recognized as the most important secondary charging point next to residential charging for plug-in electric vehicles (PEVs). The current WPC practice is spontaneous and grants every PEV a designated charger, which may not be practical or economic when there are a large number of PEVs present at workplace. This study is the first research undertaken that develops an optimization framework for WPC strategies to satisfy all charging demand while explicitly addressing different eligible levels of charging technology and employees’ demographic distributions. The optimization model is to minimize the lifetime cost of equipment, installations, and operations, and is formulated as an integer program. We demonstrate the applicability of the model using numerical examples based on national average data. The results indicate that the proposed optimization model can reduce the total cost of running a WPC system by up to 70% compared to the current practice. The WPC strategies are sensitive to the time windows and installation costs, and dominated by the PEV population size. The WPC has also been identified as an alternative sustainable transportation program to the public transit subsidy programs for both economic and environmental advantages.


      PubDate: 2015-03-15T07:13:36Z
       
  • Development of a new microscopic passing maneuver model for two-lane rural
           roads
    • Abstract: Publication date: March 2015
      Source:Transportation Research Part C: Emerging Technologies, Volume 52
      Author(s): Carlos Llorca , Ana Tsui Moreno , Annique Lenorzer , Jordi Casas , Alfredo Garcia
      Microsimulation is a useful tool to analyze traffic operation. On two-lane highways, the complexity of passing and the interaction with oncoming traffic requires specific models. This study focused on the development of a passing desire, decision and execution model. Results of the observation of 1752 maneuvers on 10 rural roads in Spain were used for this development. The model incorporated the effect of new factors such as available sight distance, delay and remaining travel time until the end of the highway segment. Outputs of the model were compared to observed data: firstly, individual passing maneuvers; secondly, traffic flow, percent followers and number of passing maneuvers in four single passing zones with two different traffic levels. The model was validated in four alternative passing zones.


      PubDate: 2015-03-15T07:13:36Z
       
  • Analysis of a cooperative variable speed limit system using microscopic
           traffic simulation
    • Abstract: Publication date: March 2015
      Source:Transportation Research Part C: Emerging Technologies, Volume 52
      Author(s): Ellen Grumert , Xiaoliang Ma , Andreas Tapani
      Variable speed limit systems where variable message signs are used to show speed limits adjusted to the prevailing road or traffic conditions are installed on motorways in many countries. The objectives of variable speed limit system installations are often to decrease the number of accidents and to increase traffic efficiency. Currently, there is an interest in exploring the potential of cooperative intelligent transport systems including communication between vehicles and/or vehicles and the infrastructure. In this paper, we study the potential benefits of introducing infrastructure to vehicle communication, autonomous vehicle control and individualized speed limits in variable speed limit systems. We do this by proposing a cooperative variable speed limit system as an extension of an existing variable speed limit system. In the proposed system, communication between the infrastructure and the vehicles is used to transmit variable speed limits to upstream vehicles before the variable message signs become visible to the drivers. The system is evaluated by the means of microscopic traffic simulation. Traffic efficiency and environmental effects are considered in the analysis. The results of the study show benefits of the infrastructure to vehicle communication, autonomous vehicle control and individualized speed limits for variable speed limit systems in the form of lower acceleration rates and thereby harmonized traffic flow and reduced exhaust emissions.


      PubDate: 2015-03-15T07:13:36Z
       
  • How I reduce fuel consumption: An experimental study on mental models of
           eco-driving
    • Abstract: Publication date: Available online 28 February 2015
      Source:Transportation Research Part C: Emerging Technologies
      Author(s): Sanna M. Pampel , Samantha L. Jamson , Daryl L. Hibberd , Yvonne Barnard
      Eco-driving has the potential to reduce fuel consumption and therefore emissions considerably. Previous research suggests that drivers have a certain level of eco-driving knowledge and skills, which they refrain from practising in their everyday lives. At the same time misconceptions and ambiguous messages from eco-driving support systems can confuse and demotivate. This research aimed to identify the mental models of eco-driving that regular drivers have. A driving simulator experiment with a varied road layout comprising urban and motorway sections was designed. The study used simple driving task instructions to investigate changes in the participants’ behaviour and thoughts in three conditions. Sixteen drivers were asked to ‘Drive normally’, ‘Drive safely’ or ‘Drive fuel-efficiently’. Behavioural measures, think aloud protocols and interviews were compared and analysed. The emphasis of this study was on eco-driving relevant indicators such as accelerating, braking, coasting and car-following. The results show that the participants do have mental models of eco-driving, which they did not use in the Baseline drive, when they were instructed to ‘Drive normally’. Misconceptions about speed and travel time provide the potential for more effective communication with the driver about the momentary efficient speed as well as resulting time losses and fuel savings. In addition, in-vehicle guidance can increase driving safety compared to practicing eco-driving without them.


      PubDate: 2015-03-15T07:13:36Z
       
  • Drivers’ ability to learn eco-driving skills; effects on fuel
           efficient and safe driving behaviour
    • Abstract: Publication date: Available online 26 February 2015
      Source:Transportation Research Part C: Emerging Technologies
      Author(s): Samantha L. Jamson , Daryl L. Hibberd , A. Hamish Jamson
      Whilst driving is inherently a safety–critical task, awareness of fuel-efficient driving techniques has gained popularity in both the public and commercial domains. Green driving, whether motivated by financial or environmental savings, has the potential to reduce the production of greenhouse gases by a significant amount. This paper focusses on the interaction between the driver and their vehicle – what type of eco-driving information is easy to use and learn whilst not compromising safety. A simulator study evaluated both visual and haptic eco-driving feedback systems in the context of hill driving. The ability of drivers to accurately follow the advice, as well as their propensity to prioritise it over safe driving was investigated. We found that any type of eco-driving advice improved performance and whilst continuous real-time visual feedback proved to be the most effective, this modality obviously reduces attention to the forward view and increases subjective workload. On the other hand, the haptic force system had little effect on reported workload, but was less effective that the visual system. A compromise may be a hybrid system that adapts to drivers’ performance on an on-going basis.


      PubDate: 2015-03-15T07:13:36Z
       
  • Exploring bikesharing travel time and trip chain by gender and day of the
           week
    • Abstract: Publication date: Available online 25 February 2015
      Source:Transportation Research Part C: Emerging Technologies
      Author(s): Jinbao Zhao , Jian Wang , Wei Deng
      As a pinnacle of green transportation with transit attributes, bikesharing has become particularly popular since the mid-2000s. Taking the opportunity of accessing to a large-scale and smart-card-based dataset from Nanjing, China, this paper explores bikesharing travel time and trip chain patterns by gender and day of the week. Bikesharing trip chain is defined and classified into four types according to the complexity of chain. Z-score analysis and visual analytic techniques, as well as chi-statistic, are adopted to explore the variation of bikesharing travel time and trip chain. The results suggest that the residential areas are the primary fountainhead where bikesharing demands generate, whilst the rail stations are the most attractive hubs that the bikesharing trips terminate at. The travel time between the same bikesharing station can be two times longer than it is from one station to another. Bikesharing travel time also differs significantly in terms of gender and day of the week. With respect to bikesharing trip chain patterns, significant variation is observed between men and women, as well as between weekdays and weekends. Findings indicate that women are more likely to make multiple-circle bikesharing trip chains than men, especially on weekdays. Moreover, the visual analytic gives bikesharing operators direct sense of the variation of bikesharing trip chain patterns with respect to gender and day of the week. Last but not least, this paper finds that there is big gap between bikesharing demand and supply in the adjacent area of rail stations in Nanjing, in particular, during afternoon peak hours.


      PubDate: 2015-03-15T07:13:36Z
       
  • Non-parametric estimation of route travel time distributions from
           low-frequency floating car data
    • Abstract: Publication date: Available online 24 February 2015
      Source:Transportation Research Part C: Emerging Technologies
      Author(s): Mahmood Rahmani , Erik Jenelius , Haris N. Koutsopoulos
      The paper develops a non-parametric method for route travel time distribution estimation using low-frequency floating car data (FCD). While most previous work has focused on link travel time estimation, the method uses FCD observations for estimating the travel time distribution on a route. Potential biases associated with the use of sparse FCD are identified. The method involves a number of steps to reduce the impact of these biases. For evaluation purposes, a case study is used to estimate route travel times from taxi FCD in Stockholm, Sweden. Estimates are compared to observed travel times for routes equipped with Automatic Number Plate Recognition (ANPR) cameras with promising results. As vehicles collecting FCD (in this case, taxis) may not be a representative sample of the overall vehicle fleet and driver population, the ANPR data along several routes are also used to assess and correct for this bias. The method is computationally efficient, scalable, and supports real time applications with large data sets through a proposed distributed implementation.


      PubDate: 2015-03-15T07:13:36Z
       
  • Event-triggered model predictive schemes for freeway traffic control
    • Abstract: Publication date: Available online 21 February 2015
      Source:Transportation Research Part C: Emerging Technologies
      Author(s): Antonella Ferrara , Simona Sacone , Silvia Siri
      Objective of the paper is to define a new freeway traffic control approach based on the Model Predictive Control methodology. The control strategy adopted is ramp metering, which is able to reduce the flow entering the mainstream from the on-ramps so as to enforce traffic regularity. To determine the ramp metering actions, an innovative MPC scheme is proposed and is characterized by two major novel aspects. First of all, the finite horizon problem to be solved has a mixed-integer linear form, so that efficient solvers can be used to find the optimal solution. Secondly, in order to reduce the number of computations, the proposed MPC scheme is of event-triggered type, i.e. the control law is not updated at each time step but only when a given set of conditions is verified. The proposed scheme is assessed in the paper via simulation showing its effectiveness in different traffic scenarios.


      PubDate: 2015-03-15T07:13:36Z
       
  • c-SPSA: Cluster-wise simultaneous perturbation stochastic approximation
           algorithm and its application to dynamic origin–destination matrix
           estimation
    • Abstract: Publication date: Available online 21 February 2015
      Source:Transportation Research Part C: Emerging Technologies
      Author(s): Athina Tympakianaki , Haris N. Koutsopoulos , Erik Jenelius
      The simultaneous perturbation stochastic approximation (SPSA) algorithm has been used in the literature for the solution of the dynamic origin–destination (OD) estimation problem. Its main advantage is that it allows quite general formulations of the problem that can include a wide range of sensor measurements. While SPSA is relatively simple to implement, its performance depends on a set of parameters that need to be properly determined. As a result, especially in cases where the gradient of the objective function changes quickly, SPSA may not be as stable and even diverge. A modification of the SPSA algorithm, referred to as c-SPSA, is proposed which applies the simultaneous perturbation approximation of the gradient within a small number of carefully constructed “homogeneous” clusters one at a time, as opposed to all elements at once. The paper establishes the theoretical properties of the new algorithm with an upper bound for the bias of the gradient estimate and shows that it is lower than the corresponding SPSA bias. It also proposes a systematic approach, based on the k-means algorithm, to identify appropriate clusters. The performance of c-SPSA, with alternative implementation strategies, is evaluated in the context of estimating OD flows in an actual urban network. The results demonstrate the efficiency of the proposed c-SPSA algorithm in finding better OD estimates and achieve faster convergence and more robust performance compared to SPSA with fewer overall number of function evaluations.


      PubDate: 2015-03-15T07:13:36Z
       
  • The role of alternative fuel vehicles: Using behavioral and sensor data to
           model hierarchies in travel
    • Abstract: Publication date: Available online 18 February 2015
      Source:Transportation Research Part C: Emerging Technologies
      Author(s): Jun Liu , Asad Khattak , Xin Wang
      Greater adoption and use of alternative fuel vehicles (AFVs) can be environmentally beneficial and reduce dependence on gasoline. The use of AFVs vis-à-vis conventional gasoline vehicles is not well understood, especially when it comes to travel choices and short-term driving decisions. Using data that contains a sufficiently large number of early AFV adopters (who have overcome obstacles to adoption), this study explores differences in use of AFVs and conventional gasoline vehicles (and hybrid vehicles). The study analyzes large-scale behavioral data integrated with sensor data from global positioning system devices, representing advances in large-scale data analytics. Specifically, it makes sense of data containing 54,043,889s of speed observations, and 65,652 trips made by 2908 drivers in 5 regions of California. The study answers important research questions about AFV use patterns (e.g., trip frequency and daily vehicle miles traveled) and driving practices. Driving volatility, as one measure of driving practice, is used as a key metric in this study to capture acceleration, and vehicular jerk decisions that exceed certain thresholds during a trip. The results show that AFVs cannot be viewed as monolithic; there are important differences within AFV use, i.e., between plug-in hybrids, battery electric, or compressed natural gas vehicles. Multi-level models are particularly appropriate for analysis, given that the data are nested, i.e., multiple trips are made by different drivers who reside in various regions. Using such models, the study also found that driving volatility varies significantly between trips, driver groups, and regions in California. Some alternative fuel vehicles are associated with calmer driving compared with conventional vehicles. The implications of the results for safety, informed consumer choices and large-scale data analytics are discussed.


      PubDate: 2015-03-15T07:13:36Z
       
  • Stochastic programming model for oversaturated intersection signal timing
    • Abstract: Publication date: Available online 18 February 2015
      Source:Transportation Research Part C: Emerging Technologies
      Author(s): Yue Tong , Lei Zhao , Li Li , Yi Zhang
      In large cities, signalized intersections often become oversaturated in rush hours due to growing traffic demand. If not controlled properly, they may collectively result in serious congestion. How to schedule traffic signals for oversaturated intersections has thus received increasing interests in recent years. Among various factors that may influence control performance, uncertainty in traffic demand remains as an important one that needs to be further studied. In some recent works, e.g., Yin (2008) and Li (2011), robust optimization models have been utilized to address uncertainty in traffic demand and to design fixed-timed signal control for oversaturated intersections. In this paper, we propose a stochastic programming (SP) model to schedule adaptive signal timing plans that minimize the expected vehicle delay. Our numerical experiments show that the proposed SP model better describes the fluctuations of traffic flows and outperforms the deterministic linear programming (LP) model in total vehicle delay, total throughput, and vehicle queue lengths. Moreover, we compare the proposed SP model with the adaptive signal control model proposed in Lin et al. (2011) to provide insights on such improvements from green time utilization and queue balancing perspectives. Furthermore, we study the feasibility of the proposed SP model in practice, with an emphasis on the required sample sizes.


      PubDate: 2015-03-15T07:13:36Z
       
  • Generalized Maximum Benefit Multiple Chinese Postman Problem
    • Abstract: Publication date: Available online 16 February 2015
      Source:Transportation Research Part C: Emerging Technologies
      Author(s): Ali Shafahi , Ali Haghani
      This research is focused on a generalization on the Max Benefit Chinese Postman Problem and the multiple vehicle variant of the Chinese Postman Problem. We call this generalization, the Generalized Maximum Benefit k-Chinese Postman Problem (GB k-CPP). We present a novel Mixed Integer Programming (MIP) formulation for the GB k-CPP. Four different cases of the model are discussed. The first case, performs arc-routing with profits and assumes that the origin and destination for each vehicle is the same for each cycle and is given by the user. The next case relaxes the assumption that the origin and destination for each vehicle should be the same and allows the users to select possible origins/destinations for vehicles. Case three gets the origin for each vehicle as input and produces a solution based on finding the best destination for each vehicle. The last case, that is very general, allows the optimization model to select possibly different locations for vehicle origin and destination, during each cycle. The different cases are applied to a security patrolling case conducted on the network of University of Maryland at College Park campus and the results are compared.


      PubDate: 2015-03-15T07:13:36Z
       
  • Optimization-based assisted calibration of traffic simulation models
    • Abstract: Publication date: Available online 14 February 2015
      Source:Transportation Research Part C: Emerging Technologies
      Author(s): David K. Hale , Constantinos Antoniou , Mark Brackstone , Dimitra Michalaka , Ana T. Moreno , Kavita Parikh
      Use of traffic simulation has increased in recent decades; and this high-fidelity modelling, along with moving vehicle animation, has allowed transportation decisions to be made with better confidence. During this time, traffic engineers have been encouraged to embrace the process of calibration, in which steps are taken to reconcile simulated and field-observed performance. According to international surveys, experts, and conventional wisdom, existing (non-automated) methods of calibration have been difficult or inadequate. There has been extensive research on improved calibration methods, but many of these efforts have not produced the flexibility and practicality required by real-world engineers. With this in mind, a patent-pending (US 61/859,819) architecture for software-assisted calibration was developed to maximize practicality, flexibility, and ease-of-use. This architecture is called SASCO (i.e. Sensitivity Analysis, Self-Calibration, and Optimization). The original optimization method within SASCO was based on “directed brute force” (DBF) searching; performing exhaustive evaluation of alternatives in a discrete, user-defined search space. Simultaneous Perturbation Stochastic Approximation (SPSA) has also gained favor as an efficient method for optimizing computationally expensive, “black-box” traffic simulations, and was also implemented within SASCO. This paper uses synthetic and real-world case studies to assess the qualities of DBF and SPSA, so they can be applied in the right situations. SPSA was found to be the fastest method, which is important when calibrating numerous inputs, but DBF was more reliable. Additionally DBF was better than SPSA for sensitivity analysis, and for calibrating complex inputs. Regardless of which optimization method is selected, the SASCO architecture appears to offer a new and practice-ready level of calibration efficiency.


      PubDate: 2015-03-15T07:13:36Z
       
  • A dynamic closed-loop vehicle routing problem with uncertainty and
           incompatible goods
    • Abstract: Publication date: Available online 13 February 2015
      Source:Transportation Research Part C: Emerging Technologies
      Author(s): Zhi-Hua Hu , Jiuh-Biing Sheu , Lei Zhao , Chung-Cheng Lu
      This study investigates a dynamic closed-loop vehicle routing problem (VRP) with uncertain pickup and deterministic delivery of incompatible goods, which is an extension of the VRP with simultaneous pickup and delivery (VRPSPD) in closed-loop logistics, where the incompatibility between goods of pickup and delivery is considered. The problem involves minimizing transportation cost, incompatibility and number of customers visited twice. A solution method based on variable neighborhood search (VNS) is developed for solving the VRPSPD. The pickup uncertainty is handled in two stages: first, a priori routes are generated by solving a VRPSPD whose pickup demands are estimated; second, the a priori routes are simulated by dynamically satisfying the pickup demand under incompatibility, and the second-round routes are generated to meet the unmet demands. The effects of considering the incompatibility are examined by experiments. A case of centralized tableware disinfection and logistics services in China’s catering industry is used for demonstration. Disinfected tableware for delivery and used tableware for pickup are incompatible because of potential cross-contamination. The experimental results quantitatively provide insights for managers who must solve the dynamic closed-loop VRP with uncertain pickup and incompatible goods. The proposed method also proves competitive for the VRPSPD.


      PubDate: 2015-03-15T07:13:36Z
       
  • Sensor location problems in path-differentiated congestion pricing
    • Abstract: Publication date: Available online 10 February 2015
      Source:Transportation Research Part C: Emerging Technologies
      Author(s): Mahmood Zangui , Yafeng Yin , Siriphong Lawphongpanich
      Path-differentiated congestion pricing is a tolling scheme that imposes tolls on paths instead of individual links. One way to implement this scheme is to deploy automated vehicle identification sensors, such as toll tag readers or license plate scanners, on roads in a network. These sensors collect vehicles’ location information to identify their paths and charge them accordingly. In this paper, we investigate how to optimally locate these sensors for the purpose of implementing path-differentiated pricing. We consider three relevant problems. The first is to locate a minimum number of sensors to implement a given path-differentiated scheme. The second is to design an optimal path-differentiated pricing scheme for a given set of sensors. The last problem is to find a path differentiated scheme to induce a given target link-flow distribution while requiring a minimum number of sensors.


      PubDate: 2015-03-15T07:13:36Z
       
  • Interface design considerations for an in-vehicle eco-driving assistance
           system
    • Abstract: Publication date: Available online 10 February 2015
      Source:Transportation Research Part C: Emerging Technologies
      Author(s): A. Hamish Jamson , Daryl L. Hibberd , Natasha Merat
      This high-fidelity driving simulator study used a paired comparison design to investigate the effectiveness of 12 potential eco-driving interfaces. Previous work has demonstrated fuel economy improvements through the provision of in-vehicle eco-driving guidance using a visual or haptic interface. This study uses an eco-driving assistance system that advises the driver of the most fuel efficient accelerator pedal angle, in real time. Assistance was provided to drivers through a visual dashboard display, a multimodal visual dashboard and auditory tone combination, or a haptic accelerator pedal. The style of advice delivery was varied within each modality. The effectiveness of the eco-driving guidance was assessed via subjective feedback, and objectively through the pedal angle error between system-requested and participant-selected accelerator pedal angle. Comparisons amongst the six haptic systems suggest that drivers are guided best by a force feedback system, where a driver experiences a step change in force applied against their foot when they accelerate inefficiently. Subjective impressions also identified this system as more effective than a stiffness feedback system involving a more gradual change in pedal feedback. For interfaces with a visual component, drivers produced smaller pedal errors with an in-vehicle visual display containing second order information on the required rate of change of pedal angle, in addition to current fuel economy information. This was supported by subjective feedback. The presence of complementary audio alerts improved eco-driving performance and reduced visual distraction from the roadway. The results of this study can inform the further development of an in-vehicle assistance system that supports ‘green’ driving.


      PubDate: 2015-03-15T07:13:36Z
       
  • Optimisation of dynamic motorway traffic via a parsimonious and
           decentralised approach
    • Abstract: Publication date: Available online 9 February 2015
      Source:Transportation Research Part C: Emerging Technologies
      Author(s): Andy H.F. Chow
      This paper presents an optimisation framework for motorway management via ramp metering and variable speed limit. We start with presenting a centralised global optimal control problem aiming to minimise the total travel delay in a motorway system. Given the centralised global optimal control solutions, we propose a set of decentralised ramp metering and speed control strategies which operate on a novel parsimonious dynamic platform without needing an underlying traffic model. The control strategies are applied to a case on UK M25 motorway. The results show that the proposed set of decentralised control is able to deliver a performance that is close to the global optimal ones with significantly less computational and implementation effort. This study provides new insights to motorway management.


      PubDate: 2015-03-15T07:13:36Z
       
  • What is the level of volatility in instantaneous driving decisions?
    • Abstract: Publication date: Available online 9 February 2015
      Source:Transportation Research Part C: Emerging Technologies
      Author(s): Xin Wang , Asad J. Khattak , Jun Liu , Golnush Masghati-Amoli , Sanghoon Son
      Driving styles can be broadly characterized as calm or volatile, with significant implications for traffic safety, energy consumption and emissions. How to quantify the extent of calm or volatile driving and explore its correlates is a key research question investigated in the study. This study contributes by leveraging a large-scale behavioral database to analyze short-term driving decisions and develop a new driver volatility index to measure the extent of variations in driving. The index captures variation in driving behavior constrained by the performance of the vehicle from a decision-making perspective. Specifically, instantaneous driving decisions include maintaining speed, accelerating, decelerating, maintaining acceleration/deceleration, or jerks to vehicle, i.e., the decision to change marginal rate of acceleration or deceleration. A fundamental understanding of instantaneous driving behavior is developed by categorizing vehicular jerk reversals (acceleration followed by deceleration), jerk enhancements (increasing accelerations or decelerations), and jerk mitigations (decreasing accelerations or decelerations). Volatility in driving decisions, captured by jerky movements, is quantified using data collected in Atlanta, GA during 2011. The database contains 51,370 trips and their associated second-by-second speed data, totaling 36 million seconds. Rigorous statistical models explore correlates of volatility that include socioeconomic variables, travel context variables, and vehicle types. The study contributes by proposing a framework that is based on defining instantaneous driving decisions in a quantifiable way using big data generated by in-vehicle GPS devices and behavioral surveys.


      PubDate: 2015-03-15T07:13:36Z
       
  • Simulation and optimization: A short review
    • Abstract: Publication date: Available online 7 February 2015
      Source:Transportation Research Part C: Emerging Technologies
      Author(s): Michel Bierlaire
      This review discusses some issues related to the use of simulation in transportation analysis. Potential pitfalls are identified and discussed. An overview of some methods relevant to the use of an advanced simulation tool in an optimization context is also provided.


      PubDate: 2015-03-15T07:13:36Z
       
  • Two-class freeway traffic regulation to reduce congestion and emissions
           via nonlinear optimal control
    • Abstract: Publication date: Available online 2 February 2015
      Source:Transportation Research Part C: Emerging Technologies
      Author(s): Cecilia Pasquale , Ioannis Papamichail , Claudio Roncoli , Simona Sacone , Silvia Siri , Markos Papageorgiou
      The objective of this paper is the regulation of freeway traffic by means of optimal control techniques. A first innovative aspect of the proposed approach is the adopted objective function in which, besides the reduction of traffic congestion (which is typically considered in traffic control schemes), the minimization of traffic emissions is also included. Moreover, a multi-class framework is defined in which two classes of vehicles (cars and trucks) are explicitly modelled, and specific control actions for each vehicle class are sought. This results in the formulation of a multi-objective optimal control problem which is described in the paper and for which a specific solution algorithm is developed and used. The algorithm exploits a specific version of the feasible direction algorithm whose effectiveness is demonstrated in the paper by means of simulation results.


      PubDate: 2015-03-15T07:13:36Z
       
  • Personalised assistance for fuel-efficient driving
    • Abstract: Publication date: Available online 9 March 2015
      Source:Transportation Research Part C: Emerging Technologies
      Author(s): Ekaterina Gilman , Anja Keskinarkaus , Satu Tamminen , Susanna Pirttikangas , Juha Röning , Jukka Riekki
      Recent advances in technology are changing the way how everyday activities are performed. Technologies in the traffic domain provide diverse instruments of gathering and analysing data for more fuel-efficient, safe, and convenient travelling for both drivers and passengers. In this article, we propose a reference architecture for a context-aware driving assistant system. Moreover, we exemplify this architecture with a real prototype of a driving assistance system called Driving coach. This prototype collects, fuses and analyses diverse information, like digital map, weather, traffic situation, as well as vehicle information to provide drivers in-depth information regarding their previous trip along with personalised hints to improve their fuel-efficient driving in the future. The Driving coach system monitors its own performance, as well as driver feedback to correct itself to serve the driver more appropriately.


      PubDate: 2015-03-10T16:43:00Z
       
 
 
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