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  • 1.
    Abrahamsson, Lars
    et al.
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Östlund, Stefan
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Schütte, Thorsten
    Söder, Lennart
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    An electromechanical moving load fixed node position and fixed node number railway power supply systems optimization model2013In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 30, p. 23-40Article in journal (Refereed)
    Abstract [en]

    This paper presents an optimization model for simulations of railway power supply systems. It includes detailed power systems modeling, train movements in discretized time considering running resistance and other mechanical constraints, and the voltage-drop-induced reduction of possible train tractive forces. The model has a fixed number of stationary power system nodes, which alleviates optimized operation overtime. The proposed model uses SOS2 (Special Ordered Sets of type 2) variables to distribute the train loads to the two most adjacent power system nodes available. The impacts of the number of power system nodes along the contact line and the discretized time step length on model accuracy and computation times are investigated. The program is implemented in GAMS. Experiences from various solver choices are also discussed. The train traveling times are minimized in the example. Other studies could e.g. consider energy consumption minimization. The numerical example is representative for a Swedish decentralized, rotary-converter fed railway power supply system. The proposed concept is however generalizable and could be applied for all kinds of moving load power system studies.

  • 2.
    Ahlström, Christer
    et al.
    Swedish National Road and Transport Research Institute (VTI), Linköping, Sweden.
    Nystrom, Marcus
    Lund University, Sweden .
    Holmqvist, Kenneth
    Lund University, Sweden .
    Fors, Carina
    Swedish National Road and Transport Research Institute (VTI), Linköping, Sweden.
    Sandberg, David
    Swedish National Road and Transport Research Institute (VTI), Linköping, Sweden.
    Anund, Anna
    Swedish National Road and Transport Research Institute (VTI), Linköping, Sweden.
    Kecklund, Goran
    Stockholm University, Sweden .
    Akerstedt, Torbjorn
    Stockholm University, Sweden .
    Fit-for-duty test for estimation of drivers sleepiness level: Eye movements improve the sleep/wake predictor2013In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 26, p. 20-32Article in journal (Refereed)
    Abstract [en]

    Driver sleepiness contributes to a considerable proportion of road accidents, and a fit-for-duty test able to measure a drivers sleepiness level might improve traffic safety. The aim of this study was to develop a fit-for-duty test based on eye movement measurements and on the sleep/wake predictor model (SWP, which predicts the sleepiness level) and evaluate the ability to predict severe sleepiness during real road driving. Twenty-four drivers participated in an experimental study which took place partly in the laboratory, where the fit-for-duty data were acquired, and partly on the road, where the drivers sleepiness was assessed. A series of four measurements were conducted over a 24-h period during different stages of sleepiness. Two separate analyses were performed; a variance analysis and a feature selection followed by classification analysis. In the first analysis it was found that the SWP and several eye movement features involving anti-saccades, pro-saccades, smooth pursuit, pupillometry and fixation stability varied significantly with different stages of sleep deprivation. In the second analysis, a feature set was determined based on floating forward selection. The correlation coefficient between a linear combination of the acquired features and subjective sleepiness (Karolinska sleepiness scale, KSS) was found to be R = 0.73 and the correct classification rate of drivers who reached high levels of sleepiness (KSS andgt;= 8) in the subsequent driving session was 82.4% (sensitivity = 80.0%, specificity = 84.2% and AUC = 0.86). Future improvements of a fit-for-duty test should focus on how to account for individual differences and situational/contextual factors in the test, and whether it is possible to maintain high sensitive/specificity with a shorter test that can be used in a real-life environment, e.g. on professional drivers.

  • 3. Ahlström, Christer
    et al.
    Nyström, Marcus
    Holmqvist, Kenneth
    Fors, Carina
    Sandberg, David
    Anund, Anna
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Fit-for-duty test for estimation of drivers' sleepiness level: Eye movements improve the sleep/wake predictor2013In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 26, p. 20-32Article in journal (Refereed)
    Abstract [en]

    Driver sleepiness contributes to a considerable proportion of road accidents, and a fit-for-duty test able to measure a driver’s sleepiness level might improve traffic safety. The aim of this study was to develop a fit-for-duty test based on eye movement measurements and on the sleep/wake predictor model (SWP, which predicts the sleepiness level) and evaluate the ability to predict severe sleepiness during real road driving. Twenty-four drivers participated in an experimental study which took place partly in the laboratory, where the fit-for-duty data were acquired, and partly on the road, where the drivers sleepiness was assessed. A series of four measurements were conducted over a 24-h period during different stages of sleepiness. Two separate analyses were performed; a variance analysis and a feature selection followed by classification analysis. In the first analysis it was found that the SWP and several eye movement features involving anti-saccades, pro-saccades, smooth pursuit, pupillometry and fixation stability varied significantly with different stages of sleep deprivation. In the second analysis, a feature set was determined based on floating forward selection. The correlation coefficient between a linear combination of the acquired features and subjective sleepiness (Karolinska sleepiness scale, KSS) was found to be R = 0.73 and the correct classification rate of drivers who reached high levels of sleepiness (KSS ⩾ 8) in the subsequent driving session was 82.4% (sensitivity = 80.0%, specificity = 84.2% and AUC = 0.86). Future improvements of a fit-for-duty test should focus on how to account for individual differences and situational/contextual factors in the test, and whether it is possible to maintain high sensitive/specificity with a shorter test that can be used in a real-life environment, e.g. on professional drivers.

  • 4.
    Ahlström, Christer
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Nyström, Marcus
    Lunds Universitet.
    Holmqvist, Kenneth
    Lunds Universitet.
    Fors, Carina
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Sandberg, David
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Anund, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Kecklund, Göran
    Stockholms Universitet.
    Ņkerstedt, Torbjörn
    Stockholms Universitet.
    Fit-for-duty test for estimation of drivers’ sleepiness level: Eye movements improve the sleep/wake predictor2013In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 26, p. 20-32Article in journal (Refereed)
    Abstract [en]

    Driver sleepiness contributes to a considerable proportion of road accidents, and a fit-for-duty test able to measure a driver’s sleepiness level might improve traffic safety. The aim of this study was to develop a fit-for-duty test based on eye movement measurements and on the sleep/wake predictor model (SWP, which predicts the sleepiness level) and evaluate the ability to predict severe sleepiness during real road driving. Twenty-four drivers participated in an experimental study which took place partly in the laboratory, where the fit-for-duty data were acquired, and partly on the road, where the drivers sleepiness was assessed. A series of four measurements were conducted over a 24-h period during different stages of sleepiness. Two separate analyses were performed; a variance analysis and a feature selection followed by classification analysis. In the first analysis it was found that the SWP and several eye movement features involving anti-saccades, pro-saccades, smooth pursuit, pupillometry and fixation stability varied significantly with different stages of sleep deprivation. In the second analysis, a feature set was determined based on floating forward selection. The correlation coefficient between a linear combination of the acquired features and subjective sleepiness (Karolinska sleepiness scale, KSS) was found to be R=. 0.73 and the correct classification rate of drivers who reached high levels of sleepiness (KSS ≥ 8) in the subsequent driving session was 82.4% (sensitivity = 80.0%, specificity = 84.2% and AUC = 0.86). Future improvements of a fit-for-duty test should focus on how to account for individual differences and situational/contextual factors in the test, and whether it is possible to maintain high sensitive/specificity with a shorter test that can be used in a real-life environment, e.g. on professional drivers. © 2012 Elsevier Ltd.

  • 5. Anand, N.
    et al.
    Meijer, D.
    van Duin, J. H. R.
    Tavasszy, L.
    Meijer, Sebastiaan
    KTH, School of Technology and Health (STH), Health Systems Engineering, Health Care Logistics. Delft Univ Technol, Netherlands.
    Validation of an agent based model using a participatory simulation gaming approach: The case of city logistics2016In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 71, p. 489-499Article in journal (Refereed)
    Abstract [en]

    Agent-based modeling is used for simulating the actions and interactions of autonomous entities aiming to assessing their effects on the system as a whole. At an abstract level, an agent-based model (ABM) is a representation of the many simple agents and interactions among them. The decision making of the agents is based on the rules given to them. In an ABM, the model output is the result of internal decision-making and may differ with alteration in the decision path. On the contrary, with the set of rules embedded in agents, their behavior is modeled to take a ‘certain action’ in a ‘certain situation’. It suggests that the internal decision making behavior of agents is truly responsible for the model output and thus it cannot be ignored while validating ABMs. This research article focuses on the validating agents’ behavior by evaluating decision-making processes of agents. For this purpose, we propose a validation framework based on a participatory simulation game. Using this framework we engage a human player (i.e. a domain stakeholder) to allow us to collect information about choices and validate the behavior of an individual agent. A proof-of-concept game is developed for a city logistics ABM to test the framework.

  • 6. Antoniou, C.
    et al.
    Koutsopoulos, Harilaos N.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Yannis, G.
    Dynamic data-driven local traffic state estimation and prediction2013In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 34, p. 89-107Article in journal (Refereed)
    Abstract [en]

    Traffic state prediction is a key problem with considerable implications in modern traffic management. Traffic flow theory has provided significant resources, including models based on traffic flow fundamentals that reflect the underlying phenomena, as well as promote their understanding. They also provide the basis for many traffic simulation models. Speed-density relationships, for example, are routinely used in mesoscopic models. In this paper, an approach for local traffic state estimation and prediction is presented, which exploits available (traffic and other) information and uses data-driven computational approaches. An advantage of the method is its flexibility in incorporating additional explanatory variables. It is also believed that the method is more appropriate for use in the context of mesoscopic traffic simulation models, in place of the traditional speed-density relationships. While these general methods and tools are pre-existing, their application into the specific problem and their integration into the proposed framework for the prediction of traffic state is new. The methodology is illustrated using two freeway data sets from Irvine, CA, and Tel Aviv, Israel. As the proposed models are shown to outperform current state-of-the-art models, they could be valuable when integrated into existing traffic estimation and prediction models.

  • 7. Chen, C.
    et al.
    Ma, J.
    Susilo, Yusak
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Liu, Y.
    Wang, M.
    The promises of big data and small data for travel behavior (aka human mobility) analysis2016In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 68, p. 285-299Article in journal (Refereed)
    Abstract [en]

    The last decade has witnessed very active development in two broad, but separate fields, both involving understanding and modeling of how individuals move in time and space (hereafter called "travel behavior analysis" or "human mobility analysis"). One field comprises transportation researchers who have been working in the field for decades and the other involves new comers from a wide range of disciplines, but primarily computer scientists and physicists. Researchers in these two fields work with different datasets, apply different methodologies, and answer different but overlapping questions. It is our view that there is much, hidden synergy between the two fields that needs to be brought out. It is thus the purpose of this paper to introduce datasets, concepts, knowledge and methods used in these two fields, and most importantly raise cross-discipline ideas for conversations and collaborations between the two. It is our hope that this paper will stimulate many future cross-cutting studies that involve researchers from both fields.

  • 8.
    Corman, Francesco
    et al.
    Swiss Fed Inst Technol, Switzerland.
    Kecman, Pavle
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
    Stochastic prediction of train delays in real-time using Bayesian networks2018In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 95, p. 599-615Article in journal (Refereed)
    Abstract [en]

    In this paper we present a stochastic model for predicting the propagation of train delays based on Bayesian networks. This method can efficiently represent and compute the complex stochastic inference between random variables. Moreover, it allows updating the probability distributions and reducing the uncertainty of future train delays in real time under the assumption that more information continuously becomes available from the monitoring system. The dynamics of a train delay over time and space is presented as a stochastic process that describes the evolution of the time-dependent random variable. This approach is further extended by modelling the interdependence between trains that share the same infrastructure or have a scheduled passenger transfer. The model is applied on a set of historical traffic realisation data from the part of a busy corridor in Sweden. We present the results and analyse the accuracy of predictions as well as the evolution of probability distributions of event delays over time. The presented method is important for making better predictions for train traffic, that are not only based on static, offline collected data, but are able to positively include the dynamic characteristics of the continuously changing delays.

  • 9.
    Dixit, Vinayak V.
    et al.
    School of Civil and Environmental Engineering, University of New South Wales, Sydney, Australia.
    Ortmann, Andreas
    Australian School of Business, University of New South Wales, Sydney, Australia.
    Rutström, Elisabet
    Örebro University, Örebro University School of Business. Center for Economic Analysis, Georgia State University, Atlanta, United States; University of Cape Town, Cape Town, South Africa.
    Ukkusuri, Satish V.
    School of Civil and Environmental Engineering at Purdue University, West Lafayette, United States.
    Experimental Economics and choice in transportation: Incentives and context2017In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 77, p. 161-184Article in journal (Refereed)
    Abstract [en]

    This paper reviews the preconditions for successful applications of Experimental Economics methods to research on transportation problems, as new transportation and research technologies emerge. We argue that the application of properly designed incentives, the hallmark of Experimental Economics, provides a high degree of experimental control, leading to internal validity and incentive compatibility. Both of these are essential for ensuring that findings generalize to contexts outside the immediate application. New technologies, such as virtual reality simulators, can generate external validity for the experiments by providing realistic contexts. GPS and other tracking technologies, as well as smart phones, smart cards and connected vehicle technologies can allow detailed observations on actions and real-time interactions with drivers in field experiments. Proper application of these new technologies in research requires an understanding of how to maintain a high level of internal validity and incentive compatibility as external validity is increased. In this review of past applications of Experimental Economics to transportation we focus on their success in achieving external and internal validity.

  • 10.
    Engelson, Leonid
    KTH, Superseded Departments, Infrastructure.
    On dynamics of traffic queues in a road network with route choice based on real time traffic information2003In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 11, no 2, p. 161-183Article in journal (Refereed)
    Abstract [en]

    Introducing real time traffic information into transportation network makes it necessary to consider development of queues and traffic flows as a dynamic process. This paper initiates a theoretical study of conditions under which this process is stable. A model is presented that describes within-one-day development of queues when drivers affected by real-time traffic information choose their paths en route. The model is reduced to a system of differential equations with delay. Equilibrium points of the system correspond to constant queue lengths. Stability of the system is investigated using characteristic values of the linearised minimal face flow. A traffic network example illustrating the method is provided.

  • 11.
    Farah, Haneen
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Koutsopoulos, Haris N.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Do cooperative systems make drivers' car-following behavior safer?2014In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 41, p. 61-72Article in journal (Refereed)
    Abstract [en]

    The main goal of in-vehicle technologies and co-operative services is to reduce congestion and increase traffic safety. This is achieved by alerting drivers on risky traffic conditions ahead of them and by exchanging traffic and safety related information for the particular road segment with nearby vehicles. Road capacity, level of service, safety, and air pollution are impacted to a large extent by car-following behavior of drivers. Car-following behavior is an essential component of micro-simulation models. This paper investigates the impact of an infrastructure-to-vehicle (I2V) co-operative system on drivers' car-following behavior. Test drivers in this experiment drove an instrumented vehicle with and without the system. Collected trajectory data of the subject vehicle and the vehicle in front, as well as socio-demographic characteristics of the test drivers were used to estimate car-following models capturing their driving behavior with and without the I2V system. The results show that the co-operative system harmonized the behavior of drivers and reduced the range of acceleration and deceleration differences among them. The observed impact of the system was largest on the older group of drivers.

  • 12.
    Farah, Haneen
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Koutsopoulos, Haris
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Saifuzzaman, Mohammad
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Kölbl, Robert
    Fuchs, Susanne
    Bankosegger, Doris
    Evaluation of the effect of cooperative infrastructure-to-vehicle systems on driver behavior2012In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 21, no 1, p. 42-56Article in journal (Refereed)
    Abstract [en]

    In-vehicle technologies and co-operative services have potential to ease congestion problems and improve traffic safety. This paper investigates the impact of infrastructure-to-vehicle co-operative systems, case of CO-OPerative SystEms for Intelligent Road Safety (COOPERS), on driver behavior. Thirty-five test drivers drove an instrumented vehicle, twice, with and without the system. Data related to driving behavior, physiological measurements, and user acceptance was collected. A macro-level approach was used to evaluate the potential impact of such systems on driver behavior and traffic safety. The results in terms of speeds, following gaps, and physiological measurements indicate a positive impact. Furthermore, drivers' opinions show that the system is in general acceptable and useful.

  • 13.
    Fors, Carina
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Kircher, Katja
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Ahlström, Christer
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Interface design of eco-driving support systems: Truck drivers’ preferences and behavioural compliance2015In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 58, p. 706-720Article in journal (Refereed)
    Abstract [en]

    The aim of the study was to investigate the perceived usefulness of various types of in-vehicle feedback and advice on fuel efficient driving. Twenty-four professional truck drivers participated in a driving simulator study. Two eco-driving support systems were included in the experiment: one that provided continuous information and one that provided intermittent information. After the simulator session, the participants were interviewed about their experiences of the various constituents of the systems. In general, the participants had a positive attitude towards eco-driving support systems and behavioural data indicated that they tended to comply with the advice given. However, different drivers had very different preferences with respect to what type of information they found useful. The majority of the participants preferred simple and clear information. The eco-driving constituents that were rated as most useful were advice on gas pedal pressure, speed guidance, feedback on manoeuvres, fuel consumption information and simple statistics. It is concluded that customisable user interfaces are recommended for eco-driving support systems for trucks.

  • 14.
    Fosgerau, Mogens
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Transport Studies, CTS.
    Fukuda, D.
    Valuing travel time variability: Characteristics of the travel time distribution on an urban road2012In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 24, p. 83-101Article in journal (Refereed)
    Abstract [en]

    This paper provides a detailed empirical investigation of the distribution of travel times on an urban road for valuation of travel time variability. Our investigation is premised on the use of a theoretical model with a number of desirable properties. The definition of the value of travel time variability depends on certain properties of the distribution of random travel times that require empirical verification. Applying a range of nonparametric statistical techniques to data giving minute-by-minute travel times for a congested urban road over a period of five months, we show that the standardized travel time is roughly independent of the time of day as required by the theory. Except for the extreme right tail, a stable distribution seems to fit the data well. The travel time distributions on consecutive links seem to share a common stability parameter such that the travel time distribution for a sequence of links is also a stable distribution. The parameters of the travel time distribution for a sequence of links can then be derived analytically from the link level distributions.

  • 15.
    Frejinger, Emma
    et al.
    École Polytechnique Fédérale de Lausanne, Transport and Mobility Laboratory.
    Bierlaire, Michel
    École Polytechnique Fédérale de Lausanne, Transport and Mobility Laboratory.
    Route choice modeling with network-free data2008In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 16, no 2, p. 187-198Article in journal (Refereed)
    Abstract [en]

    Route Choice models arc difficult to design and to estimate for various reasons. In this paper we focus on issues related to data. Indeed, real data in its original format are not related to the network used by the modeler and do therefore not correspond to path definitions. Typical examples arc data collected with the Global Positioning System (GPS) or respondents describing chosen itineraries to interviewers. Data manipulation is then necessary in order to obtain network compliant paths. We argue that such manipulations introduce bias and errors and should be avoided. We propose a general modeling framework that reconcile network-free data with a network based model without data manipulations. The concept that bridges the gap between the data and the model is called Domain of Data Relevance and corresponds to a physical area in the network where a given piece of data is relevant.

    We illustrate the framework on simple examples for two different types of data (GPS data and reported trips). Moreover, we present estimation results of Path Size Logit and Subnetwork models based on a dataset of reported trips collected in Switzerland. The network is to our knowledge the largest one used in the literature for route choice analysis based on revealed preferences data.

  • 16. Gao, Song
    et al.
    Frejinger, Emma
    KTH, School of Architecture and the Built Environment (ABE), Transport and Economics (closed 20110301), Transport and Location Analysis (closed 20110301). KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Transport Studies, CTS.
    Ben-Akiva, Moshe
    Adaptive route choices in risky traffic networks: A prospect theory approach2010In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 18, no 5, p. 727-740Article in journal (Refereed)
    Abstract [en]

    This paper deals with route choice models capturing travelers' strategic behavior when adapting to revealed traffic conditions en route in a stochastic network. The strategic adaptive behavior is conceptualized as a routing policy, defined as a decision rule that maps from all possible revealed traffic conditions to the choices of next link out of decision nodes, given information access assumptions. In this paper, we use a specialized example where a variable message sign provides information about congestion status on outgoing links. We view the problem as choice under risk and present a routing policy choice model based on the cumulative prospect theory (CPT), where utility functions are nonlinear in probabilities and thus flexible attitudes toward risk can be captured. In order to illustrate the differences between routing policy and non-adaptive path choice models as well as differences between models based on expected utility (EU) theory and CPT, we estimate models based on synthetic data and compare them in terms of prediction results. There are large differences in path share predictions and the results demonstrate the flexibility of the CPT model to represent varying degrees of risk aversion and risk seeking depending on the outcome probabilities.

  • 17.
    Ghaviha, Nima
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Bohlin, M.
    RISE SICS, Västerås, Sweden.
    Holmberg, C.
    Bombardier Transportation, Västerås, Swede.
    Dahlquist, Erik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Skoglund, Robert
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Jonasson, Daniel
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    A driver advisory system with dynamic losses for passenger electric multiple units2017In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 85, p. 111-130Article in journal (Refereed)
    Abstract [en]

    Driver advisory systems, instructing the driver how to control the train in an energy efficient manner, is one the main tools for minimizing energy consumption in the railway sector. There are many driver advisory systems already available in the market, together with significant literature on the mathematical formulation of the problem. However, much less is published on the development of such mathematical formulations, their implementation in real systems, and on the empirical data from their deployment. Moreover, nearly all the designed driver advisory systems are designed as an additional hardware to be added in drivers’ cabin. This paper discusses the design of a mathematical formulation and optimization approach for such a system, together with its implementation into an Android-based prototype, the results from on-board practical experiments, and experiences from the implementation. The system is based on a more realistic train model where energy calculations take into account dynamic losses in different components of the propulsion system, contrary to previous approaches. The experimental evaluation shows a significant increase in accuracy, as compared to a previous approach. Tests on a double-track section of the Mälaren line in Sweden demonstrates a significant potential for energy saving.

  • 18.
    Ghaviha, Nima
    et al.
    Mälardalen University, Sweden.
    Bohlin, Markus
    RISE - Research Institutes of Sweden, ICT, SICS.
    Holmberg, Christer
    Bombardier Transportation, Sweden.
    Dahlquist, Erik
    Mälardalen University, Sweden.
    Skoglund, Robert
    Mälardalen University, Sweden.
    Jonasson, Daniel
    Mälardalen University, Sweden.
    A driver advisory system with dynamic losses for passenger electric multiple units2017In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 85, p. 111-130Article in journal (Refereed)
    Abstract [en]

    Driver advisory systems, instructing the driver how to control the train in an energy efficient manner, is one the main tools for minimizing energy consumption in the railway sector. There are many driver advisory systems already available in the market, together with significant literature on the mathematical formulation of the problem. However, much less is published on the development of such mathematical formulations, their implementation in real systems, and on the empirical data from their deployment. Moreover, nearly all the designed driver advisory systems are designed as an additional hardware to be added in drivers’ cabin. This paper discusses the design of a mathematical formulation and optimization approach for such a system, together with its implementation into an Android-based prototype, the results from on-board practical experiments, and experiences from the implementation. The system is based on a more realistic train model where energy calculations take into account dynamic losses in different components of the propulsion system, contrary to previous approaches. The experimental evaluation shows a significant increase in accuracy, as compared to a previous approach. Tests on a double-track section of the Mälaren line in Sweden demonstrates a significant potential for energy saving.

  • 19. Grumert, Ellen
    et al.
    Ma, Xiaoliang
    KTH, School of Architecture and the Built Environment (ABE), Transport Science.
    Tapani, Andreas
    Analysis of a cooperative variable speed limit system using microscopic traffic simulation2015In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 52, p. 173-186Article in journal (Refereed)
    Abstract [en]

    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.

  • 20.
    Grumert, Ellen
    et al.
    Swedish National Road and Transport Research Institute, Society, environment and transport, Traffic analysis and logistics. Linköpings universitet, Kommunikations- och transportsystem.
    Ma, Xiaoliang
    Kungliga tekniska högskolan (KTH).
    Tapani, Andreas
    Swedish National Road and Transport Research Institute, Society, environment and transport, Traffic analysis and logistics. Linköpings universitet.
    Analysis of a cooperative variable speed limit system using microscopic traffic simulation2015In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 52, p. 173-186Article in journal (Refereed)
    Abstract [en]

    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.

  • 21.
    Grumert, Ellen
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology. Swedish National Road and Transport Research Institute, Sweden.
    Ma, Xiaoliang
    Kungliga tekniska högskolan (KTH), Sweden.
    Tapani, Andreas
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology. Swedish National Road and Transport Research Institute, Sweden.
    Analysis of a cooperative variable speed limitsystem using microscopic traffic simulation2015In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 52, p. 173-186Article in journal (Refereed)
    Abstract [en]

    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.

  • 22.
    Hamilton, Carl
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Transport Studies, CTS.
    Eliasson, Jonas
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Transport Studies, CTS.
    Costs and benefits of the European directive on road tolling interoperability2013In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 30, p. 221-238Article in journal (Refereed)
    Abstract [en]

    Pricing of road use in the form of tolls, congestion charges, kilometre tax and other similar schemes, is becoming increasingly common. Each toll road operator has so far decided on its own how to design and implement systems for collecting road user charges, causing a plethora of system and scheme designs. As a measure to reduce the drawbacks of such differences, the European Union has passed legislation aiming at making available interoperable road charging services, valid across all charging systems a vehicle might pass during a European journey. This legislation is setting the bar high, requiring that virtually every charging system in the Union be covered. We analyse the costs and benefits caused by this regulation, and if an adjusted regulation can improve these results. We conclude that the new legislation yields a social loss ranging from 100 to just above 500 million Euros annually. Policy suggestions to improve this result are also provided.

  • 23.
    Hamilton, Carl J.
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Transport Studies, CTS.
    Eliasson, Jonas
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Transport Studies, CTS.
    Vertical separation as means to establish interoperability in road tolling in Europe2011In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 19, no 6, p. 1019-1032Article in journal (Refereed)
    Abstract [en]

    As more European roads become tolled by various means, an increasing share of road users become subject to more than one tolling scheme in their regular driving. This can be especially burdensome for long distance hauliers, who may pass several countries and tolled motorway systems during the course of 1 day. For this reason, a range of projects have been initiated attempting to increase the level of interoperability between tolling systems, many of which with only limited success. By analyzing current incentives, costs and benefits for toll operators and road users, we conclude firstly that the current level of interoperability is likely to be lower than socially optimal, and secondly that a direct regulation making the provision of interoperability mandatory is likely to be in excess of what is socially optimal. We argue that vertically separating the monopolistic toll operators could be a cost-efficient way to achieve a socially optimal level of interoperability as a equilibrium market outcome.

  • 24.
    Hegeman, Geertje
    et al.
    DHV BV Mobility Department.
    Tapani, Andreas
    Swedish National Road and Transport Research Institute, Society, environment and transport, Traffic analysis and logistics. Linköpings universitet, Kommunikations- och transportsystem.
    Hoogendoorn, Serge
    Delft University of Technology.
    Overtaking assistant assessment using traffic simulation2009In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 17, no 6, p. 617-630Article in journal (Refereed)
    Abstract [en]

    This contribution presents the results of a microscopic traffic simulation study of the potential effects of an overtaking assistant for two-lane rural roads. The overtaking assistant is developed to support drivers in judging whether or not an overtaking opportunity can be accepted based on the distance to the next oncoming vehicle. Drivers have been found to consider this to be a difficult part of an overtaking manoeuvre. The assistants effects on traffic efficiency, driver comfort and road safety have been investigated using traffic simulation. The results indicate that this type of overtaking assistant can provide safety benefits in terms of increased average time-to-collision to the next oncoming vehicle during overtaking manoeuvres. This safety benefit can be achieved without negative consequences for traffic efficiency and driver comfort. A driver assistance system that supports the distance judging part of overtaking manoeuvres can therefore contribute to improved traffic conditions on the two-lane rural roads of the future.

  • 25.
    Hegeman, Geertje
    et al.
    DHV BV Mobility Department, Zaandam, The Netherlands.
    Tapani, Andreas
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology. Swedish National Road and Transport Research Institute (VTI), Linköping, Sweden.
    Hoogendoorn, Serge
    Delft University of Technology, Delft, The Netherlands.
    Overtaking Assistant Assessment Using Traffic Simulation2009In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 17, no 6, p. 617-630Article in journal (Refereed)
    Abstract [en]

    This paper presents the results of a microscopic traffic simulationstudy of the potential effects of an overtaking assistant fortwo-lane rural roads. The overtaking assistant is developed to supportdrivers in judging whether or not an overtaking opportunitycan be accepted based on the distance to the next oncoming vehicle.Drivers have been found to consider this to be a difficultpart of an overtaking manoeuvre. The assistant’s effects on trafficefficiency, driver comfort and road safety have been investigatedusing traffic simulation. The results indicate that this type overtakingassistant can provide safety benefits in terms of increasedtime-to-collision to the next oncoming vehicle during overtakingmanoeuvres. This safety benefit can be achieved without negativeconsequences for traffic efficiency and driver comfort. A driverassistance system that supports the distance judging part of overtakingmanoeuvres can therefore contribute to improved trafficconditions on the two-lane rural roads of the future.

  • 26.
    Josyula, Sai Prashanth
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science and Engineering.
    Törnquist Krasemann, Johanna
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science and Engineering.
    Lundberg, Lars
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science and Engineering.
    A parallel algorithm for train rescheduling2018In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 95, p. 545-569Article in journal (Refereed)
    Abstract [en]

    One of the crucial factors in achieving a high punctuality in railway traffic systems, is the ability to effectively reschedule the trains when disturbances occur. The railway traffic rescheduling problem is a complex task to solve both from a practical and a computational perspective. Problems of practically relevant sizes have typically a very large search space, making them time-consuming to solve even for state-of-the-art optimization solvers. Though competitive algorithmic approaches are a widespread topic of research, not much research has been done to explore the opportunities and challenges in parallelizing them. This paper presents a parallel algorithm to efficiently solve the real-time railway rescheduling problem on a multi-core parallel architecture. We devised (1) an effective way to represent the solution space as a binary tree and (2) a novel sequential heuristic algorithm based on a depth-first search (DFS) strategy that quickly traverses the tree. Based on that, we designed a parallel algorithm for a multi-core architecture, which proved to be 10.5 times faster than the sequential algorithm even when run on a single processing core. When executed on a parallel machine with 8 cores, the speed further increased by a factor of 4.68 and every disturbance scenario in the considered case study was solved within 6 s. We conclude that for the problem under consideration, though a sequential DFS approach is fast in several disturbance scenarios, it is notably slower in many other disturbance scenarios. The parallel DFS approach that combines a DFS with simultaneous breadth-wise tree exploration, while being much faster on an average, is also consistently fast across all scenarios.

  • 27.
    Klügl, Franziska
    et al.
    Örebro University.
    Bazzan, Ana L. C.
    Univ Fed Rio Grande do Sul, Porto Alegre RS, Brazil.
    Ossowski, Sascha
    Univ Rey Juan Carlos, Madrid, Spain.
    Agents in traffic and transportation Preface2010In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 18, no 1, p. 69-70Article in journal (Refereed)
  • 28.
    Krasemann, Johanna Törnquist
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science and Engineering.
    Design of an effective algorithm for fast response to the re-scheduling of railway traffic during disturbances2012In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 20, no 1, p. 62-78Article in journal (Refereed)
    Abstract [en]

    An attractive and sustainable railway traffic system is characterized by having a high security, high accessibility, high energy performance and offering reliable services with sufficient punctuality. At the same time, the network is to be utilized to a large extent in a cost-effective way. This requires a continuous balance between maintaining a high utilization and sufficiently high robustness to minimize the sensitivity to disturbances. The occurrence of some disturbances can be prevented to some extent but the occurrence of unpredictable events are unavoidable and their consequences then need to be analyzed, minimized and communicated to the affected users. Valuable information necessary to perform a complete consequence analysis of a disturbance and the re-scheduling is however not always available for the traffic managers. With current conditions, it is also not always possible for the traffic managers to take this information into account since he or she needs to act fast without any decision-support assisting in computing an effective re-scheduling solution. In previous research we have designed an optimization-based approach for re-scheduling which seems promising. However, for certain scenarios it is difficult to find good solutions within seconds. Therefore, we have developed a greedy algorithm which effectively delivers good solutions within the permitted time as a complement to the previous approach. To quickly retrieve a feasible solution the algorithm performs a depth-first search using an evaluation function to prioritise when conflicts arise and then branches according to a set of criteria.

  • 29.
    Larsson, Erik
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Sennton, Gustav
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Larson, Jeffrey
    The vehicle platooning problem: Computational complexity and heuristics2015In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 60, p. 258-277Article in journal (Refereed)
    Abstract [en]

    We create a mathematical framework for modeling trucks traveling in road networks, and we define a routing problem called the platooning problem. We prove that this problem is NP-hard, even when the graph used to represent the road network is planar. We present integer linear programming formulations for instances of the platooning problem where deadlines are discarded, which we call the unlimited platooning problem. These allow us to calculate fuel-optimal solutions to the platooning problem for large-scale, real-world examples. The problems solved are orders of magnitude larger than problems previously solved exactly in the literature. We present several heuristics and compare their performance with the optimal solutions on the German Autobahn road network. The proposed heuristics find optimal or near-optimal solutions in most of the problem instances considered, especially when a final local search is applied. Assuming a fuel reduction factor of 10% from platooning, we find fuel savings from platooning of 1-2% for as few as 10 trucks in the road network; the percentage of savings increases with the number of trucks. If all trucks start at the same point, savings of up to 9% are obtained for only 200 trucks.

  • 30.
    Lidén, Tomas
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Joborn, Martin
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    An optimization model for integrated planning of railway traffic and network maintenance2017In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 74, p. 327-347Article in journal (Refereed)
    Abstract [en]

    Abstract Railway transportation systems are important for society and have many challenging and important planning problems. Train services as well as maintenance of a railway network need to be scheduled efficiently, but have mostly been treated as two separate planning problems. Since these activities are mutually exclusive they must be coordinated and should ideally be planned together. In this paper we present a mixed integer programming model for solving an integrated railway traffic and network maintenance problem. The aim is to find a long term tactical plan that optimally schedules train free windows sufficient for a given volume of regular maintenance together with the wanted train traffic. A spatial and temporal aggregation is used for controlling the available network capacity. The properties of the proposed model are analyzed and computational experiments on various synthetic problem instances are reported. Model extensions and possible modifications are discussed as well as future research directions.

  • 31.
    Ma, Xiaoliang
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport and Economics (closed 20110301). KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Jansson, Magnus
    KTH, School of Electrical Engineering (EES), Signal Processing.
    A general Kalman-filter based model estimation method for car-following dynamics in traffic simulation2006In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359Article in journal (Other academic)
  • 32.
    Marell, Agneta
    et al.
    Umeå University, Faculty of Social Sciences, Umeå School of Business.
    Westin, Kerstin
    Umeå University, Faculty of Social Sciences, Department of Social and Economic Geography.
    Intelligent transportation system and traffic safety: – drivers perception and acceptance of electronic speed checkers1999In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 7, no 2-3, p. 131-147Article in journal (Refereed)
    Abstract [en]

    Intelligent Transportation System (ITS) can play an important role in reducing risks and increasing traffic safety. Discussion as to whether a technological approach or a behavioral approach is the right way to achieve a safer traffic environment forms a point of departure for this paper. On the one hand, there are the technicians who emphasize technology as the way towards safer traffic. Behaviorists, on the other hand, view the drivers’ behavior as fundamental and argue that education and incentive-oriented policies are essential in order to influence the driver and therefore increase traffic safety. Independent of the approach advocated a successful outcome of either a technological improvement, or an information campaign, has to be based on a high level of acceptance among potential users. In order to increase traffic safety, it is therefore essential to recognize driver motivation and attitudes. In this paper we focus on drivers’ attitudes towards risk, traffic safety and safety measures. A study of drivers’ attitudes and acceptance of an electronic device for speed checking (which the drivers tested for nine months) indicated a high acceptance level. The drivers perceived that they had both become more aware of traffic regulations and behaved in accordance with safety regulations.

  • 33.
    Marell, Agneta
    et al.
    Umeå University, Faculty of Social Sciences, Umeå School of Business and Economics (USBE), Business Administration.
    Westin, Kerstin
    Umeå University, Faculty of Social Sciences, Department of Geography and Economic History.
    Intelligent transportation systems and traffic safety – Drivers perception and acceptance of electronic speed checkers.1999In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 7, no 2/3, p. 131-147Article in journal (Refereed)
  • 34. Midya, Surajit
    et al.
    Thottappillil, Rajeev
    An overview of electromagnetic compatibility challenges in European Rail Traffic Management System2008In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 16, no 5, p. 515-534Article in journal (Refereed)
    Abstract [en]

    In Europe, the railway industry is rapidly getting transformed from traditional mode of public transportation to a very fast, more reliable, long distance and cross country operation. A new concept, called European Rail Traffic Management System (ERTMS) is originated to make this transition smooth, reliable and compatible among different countries. Electromagnetic interference and compatibility (EMC) issues play a major role on the overall system design and performance of this. In this paper, an overview of the operational principles and major components of ERTMS and other modern railway systems are discussed in detail with an emphasis on possible EMC issues. Radiated and conducted interferences originated from different sources and their consequences on different subsystems and components are discussed and analyzed.

  • 35.
    Midya, Surajit
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Thottappillil, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    An overview of electromagnetic compatibility challenges in European Rail Traffic Management System2008In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 16, no 5, p. 515-534Article, review/survey (Refereed)
    Abstract [en]

    In Europe, the railway industry is rapidly getting transformed from traditional mode of public transportation to a very fast, more reliable, long distance and cross country operation. A new concept, called European Rail Traffic Management System (ERTMS) is originated to make this transition smooth, reliable and compatible among different countries. Electromagnetic interference and compatibility (EMC) issues play a major role on the overall system design and performance of this. In this paper, an overview of the operational principles and major components of ERTMS and other modern railway systems are discussed in detail with an emphasis on possible EMC issues. Radiated and conducted interferences originated from different sources and their consequences on different subsystems and components are discussed and analyzed.

  • 36.
    Olstam, Johan
    et al.
    Swedish National Road and Transport Research Institute, Society, environment and transport, Traffic analysis and logistics. Linköpings universitet, Kommunikations- och transportsystem.
    Espié, Stéphane
    INRETS, Institut National de REcherche sur les Transports et leur Sécurité, 58, Bd Lefebvre F-75732 Paris, France.
    Mårdh, Selina
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Jansson, Jonas
    Swedish National Road and Transport Research Institute, Traffic and road users, Vehicle technology and simulation.
    Lundgren, Jan
    Linköpings universitet, Institutionen för teknik och naturvetenskap.
    An algorithm for combining autonomous vehicles and controlled events in driving simulator experiments2011In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 19, no 6, p. 1185-1201Article in journal (Refereed)
    Abstract [en]

    Autonomous vehicles can be used to create realistic simulations of surrounding vehicles in driving simulators. However, the use of autonomous vehicles makes it difficult to ensure reproducibility between subjects. In this paper, an effort is made to solve the problem by combining autonomous vehicles and controlled events, denoted plays. The aim is to achieve the same initial play conditions for each subject, since the traffic situation around the subject will be dependant upon each subject's actions while driving in the autonomous traffic. This paper presents an algorithm that achieves the transition from autonomous traffic to a predefined start condition for a play. The algorithm has been tested in the VTI driving simulator III with promising results. In most of the cases the algorithm could reconstruct the specified start condition and conduct the transition from autonomous to controlled mode in a non-conspicuous way. Some problems were observed regarding moving unwanted vehicles away from the closest area around the simulator vehicle, and this part of the algorithm has to be enhanced. The experiment also showed that the controlled every-day life traffic normally used in the VTI driving simulator makes subjects drive faster than in autonomous traffic.

  • 37.
    Olstam, Johan
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Espié, Stéphane
    INRETS, Institut National de REcherche sur les Transports et leur Sécurité, 58, Bd Lefebvre F-75732 Paris, France.
    Mårdh, Selina
    Swedish National Road and Transport Research Institute (VTI), VTI, SE-581 95 Linköping, Sweden.
    Jansson, Jonas
    Swedish National Road and Transport Research Institute (VTI), VTI, SE-581 95 Linköping, Sweden .
    Lundgren, Jan
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    An algorithm for combining autonomous vehicles and controlled events in driving simulator experiments2011In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 19, no 6, p. 1185-1201Article in journal (Refereed)
    Abstract [en]

    Autonomous vehicles can be used to create realistic simulations of surrounding vehicles in driving simulators. However, the use of autonomous vehicles makes it difficult to ensure reproducibility between subjects. In this paper, an effort is made to solve the problem by combining autonomous vehicles and controlled events, denoted plays. The aim is to achieve the same initial play conditions for each subject, since the traffic situation around the subject will be dependant upon each subject's actions while driving in the autonomous traffic. This paper presents an algorithm that achieves the transition from autonomous traffic to a predefined start condition for a play. The algorithm has been tested in the VTI driving simulator III with promising results. In most of the cases the algorithm could reconstruct the specified start condition and conduct the transition from autonomous to controlled mode in a non-conspicuous way. Some problems were observed regarding moving unwanted vehicles away from the closest area around the simulator vehicle, and this part of the algorithm has to be enhanced. The experiment also showed that the controlled every-day life traffic normally used in the VTI driving simulator makes subjects drive faster than in autonomous traffic.

  • 38.
    Rahmani, Mahmood
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Jenelius, Erik
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Koutsopoulos, Haris
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering. Northeastern University, United States.
    Non-parametric estimation of route travel time distributions from low-frequency floating car data2015In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 58B, p. 343-362Article in journal (Refereed)
    Abstract [en]

    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.

  • 39.
    Rahmani, Mahmood
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Koutsopoulos, Hans N.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Path inference from sparse floating car data for urban networks2013In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 30, p. 41-54Article in journal (Refereed)
    Abstract [en]

    The use of probe vehicles in traffic management is growing rapidly. The reason is that the required data collection infrastructure is increasingly in place in urban areas with a significant number of mobile sensors constantly moving and covering expansive areas of the road network. In many cases, the data is sparse in time and location and includes only geo-location and timestamp. Extracting paths taken by the vehicles from such sparse data is an important step towards travel time estimation and is referred to as the map-matching and path inference problem. This paper introduces a path inference method for low-frequency floating car data, assesses its performance, and compares it to recent methods using a set of ground truth data.

  • 40.
    Rahmani, Mahmood
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Koutsopoulos, Haris N.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering. Northeastern University, United States.
    Jenelius, Erik
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Travel time estimation from sparse floating car data with consistent path inference: A fixed point approach2017In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 85, p. 628-643Article in journal (Refereed)
    Abstract [en]

    Estimation of urban network link travel times from sparse floating car data (FCD) usually needs pre-processing, mainly map-matching and path inference for finding the most likely vehicle paths that are consistent with reported locations. Path inference requires a priori assumptions about link travel times; using unrealistic initial link travel times can bias the travel time estimation and subsequent identification of shortest paths. Thus, the combination of path inference and travel time estimation is a joint problem. This paper investigates the sensitivity of estimated travel times, and proposes a fixed point formulation of the simultaneous path inference and travel time estimation problem. The methodology is applied in a case study to estimate travel times from taxi FCD in Stockholm, Sweden. The results show that standard fixed point iterations converge quickly to a solution where input and output travel times are consistent. The solution is robust under different initial travel times assumptions and data sizes. Validation against actual path travel time measurements from the Google API and an instrumented vehicle deployed for this purpose shows that the fixed point algorithm improves shortest path finding. The results highlight the importance of the joint solution of the path inference and travel time estimation problem, in particular for accurate path finding and route optimization.

  • 41. Toledo, Tomer
    et al.
    Cats, Oded
    Burghout, Wilco
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR. KTH, School of Architecture and the Built Environment (ABE), Transport and Economics.
    Koutsopoulos, Harilaos
    KTH, School of Architecture and the Built Environment (ABE), Transport and Economics, Traffic and Logistics.
    Mesoscopic simulation for transit operations2010In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 18, no 6, p. 896-908Article in journal (Refereed)
    Abstract [en]

    This paper presents a transit simulation model designed to support evaluation of operations, planning and control, especially in the context of Advanced Public Transportation Systems (APTS). Examples of potential applications include frequency determination, evaluation of real-time control strategies for schedule maintenance and assessing the effects of vehicle scheduling on the level of service. Unlike most previous efforts in this area, the simulation model is built on a platform of a mesoscopic traffic simulation model, which allows modeling of the operation dynamics of large-scale transit systems taking into account the stochasticity due to interactions with road traffic. The capabilities of Mezzo as an evaluation tool of transit operations are demonstrated with an application to a real-world high-demand bus line in the Tel-Aviv metropolitan area under various scenarios. The headway distributions at two stops are compared with field observations and show good consistency between simulated and observed data.

  • 42. Toledo, Tomer
    et al.
    Koutsopoulos, Haris
    KTH, School of Architecture and the Built Environment (ABE), Transport and Economics (closed 20110301), Traffic and Logistics (closed 20110301).
    Ben-Akiva, Moshe
    Estimation of an Integrated Driving Behavior Mode2009In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 17, no 4Article in journal (Refereed)
  • 43. Toledo, Tomer
    et al.
    Koutsopoulos, Haris N.
    KTH, School of Architecture and the Built Environment (ABE), Transport and Economics (closed 20110301), Traffic and Logistics (closed 20110301).
    Ben-Akiva, Moshe
    Estimation of an integrated driving behavior model2009In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 17, no 4, p. 365-380Article in journal (Refereed)
    Abstract [en]

    This paper presents the methodology and results of estimation of an integrated driving behavior model that attempts to integrate various driving decisions. The model explains lane changing and acceleration decisions jointly and so, captures inter-dependencies between these behaviors and represents drivers' planning capabilities. It introduces new models that capture drivers' choice of a target gap that they intend to use in order to change lanes, and acceleration models that capture drivers' behavior to facilitate the completion of a desired lane change using the target gap. The parameters of all components of the model are estimated simultaneously with the maximum likelihood method and using detailed vehicle trajectory data collected in a freeway section in Arlington, Virginia. The estimation results are presented and discussed in detail.

  • 44. Toledo, Tomer
    et al.
    Koutsopoulos, Haris N.
    Ben-Akiva, Moshe
    Integrated driving behavior modeling2007In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 15, no 2, p. 96-112Article in journal (Refereed)
    Abstract [en]

    This paper develops, implements and tests a framework for driving behavior modeling that integrates the various decisions, such as acceleration, lane changing and gap acceptance. Furthermore, the proposed framework is based on the concepts of short-term goal and short-term plan. Drivers are assumed to conceive and perform short-term plans in order to accomplish short-term goals. This behavioral framework supports a more realistic representation of the driving task, since it captures drivers’ planning capabilities and allows decisions to be based on anticipated future conditions.

    An integrated driving behavior model, which utilizes these concepts, is developed. The model captures both lane changing and acceleration behaviors. The driver’s short-term goal is defined by the target lane. Drivers who wish to change lanes but cannot change lanes immediately, select a short-term plan to perform the desired lane change. Short-term plans are defined by the various gaps in traffic in the target lane. Drivers adapt their acceleration behavior to facilitate the lane change using the target gap. Hence, inter-dependencies between lane changing and acceleration behaviors are captured.

  • 45.
    Tympakianaki, Athina
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport planning, economics and engineering.
    Koutsopoulos, Hans N.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport planning, economics and engineering. Department of Civil and Environmental Engineering, Northeastern University, Boston, MA, United States .
    Jenelius, Erik
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport planning, economics and engineering.
    c-SPSA: Cluster-wise simultaneous perturbation stochastic approximation algorithm and its application to dynamic origin-destination matrix estimation2015In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 55, p. 231-245Article in journal (Refereed)
    Abstract [en]

    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.

  • 46.
    Tympakianaki, Athina
    et al.
    Technical University of Crete, Greece .
    Spiliopoulou, A.
    Kouvelas, A.
    Papamichail, I.
    Papageorgiou, M.
    Wang, Y.
    Real-time merging traffic control for throughput maximization at motorway work zones2014In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 44, p. 242-252Article in journal (Refereed)
    Abstract [en]

    Work zones on motorways necessitate the drop of one or more lanes which may lead to significant reduction of traffic flow capacity and efficiency, traffic flow disruptions, congestion creation, and increased accident risk. Real-time traffic control by use of green-red traffic signals at the motorway mainstream is proposed in order to achieve safer merging of vehicles entering the work zone and, at the same time, maximize throughput and reduce travel delays. A significant issue that had been neglected in previous research is the investigation of the impact of distance between the merge area and the traffic lights so as to achieve, in combination with the employed real-time traffic control strategy, the most efficient merging of vehicles. The control strategy applied for real-time signal operation is based on an ALINEA-like proportional-integral (PI-type) feedback regulator. In order to achieve maximum performance of the control strategy, some calibration of the regulator's parameters may be necessary. The calibration is first conducted manually, via a typical trial-and-error procedure. In an additional investigation, the recently proposed learning/adaptive fine-tuning (AFT) algorithm is employed in order to automatically fine-tune the regulator parameters. Experiments conducted with a microscopic simulator for a hypothetical work zone infrastructure, demonstrate the potential high benefits of the control scheme.

  • 47. Vythoulkas, P. C.
    et al.
    Koutsopoulos, Harilaos
    Modeling discrete choice behavior using concepts from fuzzy set theory, approximate reasoning and neural networks2003In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 11, no 1, p. 51-73Article in journal (Refereed)
    Abstract [en]

    Models of discrete choice analysis are usually based on the random utility framework. They assume that decision makers make decisions that maximize their utility. Alternative formulations of the problem have also been proposed in the literature. These approaches model the decision makers' perceptions of the attributes of the various alternatives using fuzzy sets and linguistic variables, and the decision process itself, using concepts from approximate reasoning and fuzzy control. The underlying assumption is that decision makers use a few simple rules that relate their vague perceptions of the various attributes to their preferences towards the available alternatives. The paper extends this approach by incorporating rule weights, which capture the importance of a particular rule in the decision process. It also presents an approach for calibrating the weights using concepts from neural networks. A case study, involving mode choice, is used to demonstrate the potential of the approach and compare it to alternative formulations and methodologies.

  • 48.
    Xiong, Zhitao
    et al.
    University of New South Wales,.
    Olstam, Johan
    Swedish National Road and Transport Research Institute, Society, environment and transport, Traffic analysis and logistics.
    Orchestration of driving simulator scenarios based on dynamic actor preparation and automated action planning2015In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 56, p. 120-131Article in journal (Refereed)
    Abstract [en]

    In driving simulation, a scenario includes definitions of the road environment, the traffic situation, simulated vehicles’ interactions with the participant’s vehicle and measurements that need to be collected. The scenarios need to be designed in such a way that the research questions to be studied can be answered, which commonly imply exposing the participant for a couple of predefined specific situations that has to be both realistic and repeatable. This article presents an integrated algorithm based on Dynamic Actor Preparation and Automated Action Planning to control autonomous simulated vehicles in the simulation in order to generate predefined situations. This algorithm is thus able to plan driving actions for autonomous vehicles based on specific tasks with relevant contextual information as well as handling longitudinal transportation of simulated vehicles based on the contextual information in an automated manner. The conducted experiment shows that the algorithm is able to guarantee repeatability under autonomous traffic flow. The presented algorithm can benefit not only the driving simulation community, but also relevant areas, such as autonomous vehicle and in-vehicle device design by providing them with an algorithm for target pursue and driving task accomplishment, which can be used to design a human-vehicle cooperation system in the coming era of autonomous driving.

  • 49.
    Xiong, Zhitao
    et al.
    The University of New South Wales.
    Olstam, Johan
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Orchestration of driving simulator scenarios based on dynamic actor preparation and automated action planning2015In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 56, p. 120-131Article in journal (Refereed)
    Abstract [en]

    In driving simulation, a scenario includes definitions of the road environment, the traffic situation, simulated vehicles’ interactions with the participant’s vehicle and measurements that need to be collected. The scenarios need to be designed in such a way that the research questions to be studied can be answered, which commonly imply exposing the participant for a couple of predefined specific situations that has to be both realistic and repeatable. This article presents an integrated algorithm based on Dynamic Actor Preparation and Automated Action Planning to control autonomous simulated vehicles in the simulation in order to generate predefined situations. This algorithm is thus able to plan driving actions for autonomous vehicles based on specific tasks with relevant contextual information as well as handling longitudinal transportation of simulated vehicles based on the contextual information in an automated manner. The conducted experiment shows that the algorithm is able to guarantee repeatability under autonomous traffic flow. The presented algorithm can benefit not only the driving simulation community, but also relevant areas, such as autonomous vehicle and in-vehicle device design by providing them with an algorithm for target pursue and driving task accomplishment, which can be used to design a human-vehicle cooperation system in the coming era of autonomous driving.

  • 50.
    Xylia, Maria
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy and Climate Studies, ECS.
    Leduc, Sylvain
    International Institute for Applied Systems Analysis (IIASA).
    Patrizio, Piera
    International Institute for Applied Systems Analysis (IIASA).
    Kraxner, Florian
    International Institute for Applied Systems Analysis (IIASA).
    Silveira, Semida
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy and Climate Studies, ECS.
    Locating charging infrastructure for electric buses in Stockholm2017In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 78, no 2017, p. 183-200Article in journal (Refereed)
    Abstract [en]

    Charging infrastructure requirements are being largely debated in the context of urban energy planning for transport electrification. As electric vehicles are gaining momentum, the issue of locating and securing the availability, efficiency and effectiveness of charging infrastructure becomes a complex question that needs to be addressed. This paper presents the structure and application of a model developed for optimizing the distribution of charging infrastructure for electric buses in the urban context, and tests the model for the bus network of Stockholm. The major public bus transport hubs connecting to the train and subway system show the highest concentration of locations chosen by the model for charging station installation. The costs estimated are within an expected range when comparing to the annual bus public transport costs in Stockholm. The model could be adapted for various urban contexts to promptly assist in the transition to fossil-free bus transport. The total costs for the operation of a partially electrified bus system in both optimization cases considered (cost and energy) differ only marginally from the costs for a 100% biodiesel system. This indicates that lower fuel costs for electric buses can balance the high investment costs incurred in building charging infrastructure, while achieving a reduction of up to 51% in emissions and up to 34% in energy use in the bus fleet.  

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