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  • 1.
    Andreasson, Ingmar J.
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Extending PRT capabilities2009In: Automated People Movers 2009: Connecting People, Connecting Places, Connecting Modes: Proceedings of the twelfth international conference, May 31-June 3, 2009 : Atlanta, Georgia, American Society of Civil Engineers (ASCE), 2009, p. 343-349Conference paper (Refereed)
    Abstract [en]

    Personal Rapid Transit (PRT) offers direct, on-demand travel in automated vehicles seating 3-6 passengers on exclusive right-of-way. Commercially available systems now offer speeds up to 45 kph at headways from 3 seconds. With 3-second headways, a typical load of 1.5 passengers and 30 empty vehicles, the link capacity will be 1200 passengers per hour (one direction). This paper explores ways to extend the capabilities of PRT with respect to capacity and speed. Strategies have been developed and verified with the generic simulation software PRTsim.

  • 2.
    Andreasson, Ingmar J.
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Personal Rapid Transit as Feeder-Distributor to Rail2012In: Transportation Research Record, ISSN 0361-1981, E-ISSN 2169-4052, no 2275, p. 88-93Article in journal (Refereed)
    Abstract [en]

    Efficient feeder distributor systems around train stations are important in attracting train passengers. Such systems would be a suitable application for personal rapid transit (PRT). This paper suggests layouts and operations strategies for transfer stations between PRT and heavy rail. Ticket handling can be avoided by having the train fare include PRT trips. Ridesharing can be encouraged by destination signs. The catchment area that can be efficiently served is related to the interval between trains. The capacity of the station and guideway can be improved by coupling PRT vehicles in the station and decoupling them as necessary en route. Applications in Sweden are illustrated with the PRTsim software. In one case, outgoing PRT vehicles were loaded to 78%.

  • 3.
    Archer, Jeffery
    KTH, School of Architecture and the Built Environment (ABE), Transport and Economics, Traffic and Logistics. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Indicators for traffic safety assessment and prediction and their application in micro-simulation modelling: a study of urban and suburban intersections2005Doctoral thesis, monograph (Other scientific)
    Abstract [en]

    In order to achieve sustainable long-term transport infrastructure development, there is a growing need for fast, reliable and effective methods to evaluate and predict the impact of traffic safety measures. Recognising this need, and the need for an active traffic safety approach, this thesis focuses on traffic safety assessment and prediction based on the use of safety indicators that measure the spatial and/or temporal proximity of safety critical events. The main advantage of such measures is that they occur more frequently than accidents, and therefore require relatively short periods of study to establish values that can later be used for comparison, or for accident prediction purposes. There are a number of more generally accepted safety indicators including: Time-to-Accident, Time-to-Collision, and Post-Encroachment Time. These are based on different underlying principles and measurement techniques, including both on-site subjective estimation, and objective photometric measures.

    A major part of the work presented in this thesis, concerns identifying the potential and limitations of the different safety indicators with regard to their validity and reliability, and practical use for safety assessment and prediction purposes. This is done in conjunction with field studies in the urban and suburban environment, at both signalised and unsignalised intersections. Results from these studies indicate that on-site observation methods provide useful quantitative and qualitative information relatively quickly and efficiently, provided that they are used correctly. On the other hand, the methods based on photometric measurement (video-analysis) proved arduous and time-consuming. Furthermore, there are questions regarding the abilities of the Time-to-Collision and Post-Encroachment Time safety indicators to adequately represent interaction severity, suggesting possible flaws in fundamental concepts related to construct validity. Importantly, results showed that the relationship between safety indicators and traffic accidents is complex and equivocal, where many different factors and processes can impose a significant influence on safety. This makes generalised predictive modelling a particularly difficult task for safety analysts.

    The potential of micro-simulation for traffic safety and performance estimation based on the use of safety indicators was investigated in the second part of this thesis. Microscopic traffic simulation has become increasingly popular among transport planners, due to the fact that it serves as a safe and flexible off-line test environment for the estimation of dynamic and complex traffic system effects. It is useful and cost-effective in relation to the evaluation of issues concerning roadway design, and technological systems that influence road-user behaviour and vehicle performance. For reasons related to modelling fidelity and data quality, simulation has seldom been used for traffic safety estimation. Simulation model development is however, undergoing rapid development and the area of ‘safety-simulation’ and is recognised as having a high potential in the field of transport planning and traffic engineering.

    As part of the work in this thesis, practical simulation experiments were carried out to investigate this potential, and identify limitations. Based on the data from one of the earlier studies, and knowledge regarding important safety-influencing factors and behavioural processes, one of the simulation experiments showed evidence to suggest that realistic safety critical events could be generated and measured using safety indicators in a simulation environment, without making unnecessary and unrealistic behavioural assumptions. Furthermore, a second application of this methodology revealed the safety potential of a rear-end incident-reduction function used in standard vehicle actuated signalling. While both of these simulation studies highlighted the potential of this type of approach, the need for more flexible and realistic models of interactive behavioural processes could be identified in addition to the general need for greater active research into the field of safety simulation.

  • 4.
    Avery, Ryan
    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.
    Burghout, Wilco
    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.
    Andréasson, Ingmar
    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.
    An Interactive Tool for Collecting Traveler Behavior Information2008Conference paper (Refereed)
  • 5.
    Burghout, Wilco
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Viewpoint: The growing role of dynamic modelling2011In: Impact, ISSN 2045-0141, Vol. May/June, no 37, p. 17-19Article in journal (Other academic)
  • 6.
    Burghout, Wilco
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport and Economics (closed 20110301), Traffic and Logistics (closed 20110301). KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Cats, Oded
    KTH, School of Architecture and the Built Environment (ABE), Transport and Economics (closed 20110301), Traffic and Logistics (closed 20110301).
    Toledo, Tomer
    Koutsopoulos, Haris
    KTH, School of Architecture and the Built Environment (ABE), Transport and Economics (closed 20110301), Traffic and Logistics (closed 20110301).
    DYMOBUS: dynamic mesoscopic modelling of bus public transport2009In: Conference proceedings to ITS 2009 conference, 2009Conference paper (Refereed)
    Abstract [en]

    In today’s public bus transport punctuality is one of the main problems to deal with for traffic planners and operators, especially in large cities such as Stockholm. The current static models do not handle congestion delays and the interaction between bus and car traffic, leading to overly optimistic timetables and hard to manage delays. In the DYMOBUS project (Funded by VINNOVA and City of Stockholm) a dynamic modelling tool was developed in order to study these interactions. This paper discusses a mesoscopic, mixed-traffic, 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 applications include frequency determination, evaluation of real time control strategies for schedule maintenance and restoration from major disruptions. The transit simulation component is designed to represent realistically the uncertainty in operations, in order to assess service reliability. The simulation models all sources of uncertainty: chaining of trips, travel time variability, behavior at stops and a detailed representation of passenger demand at the various stops. Unlike most previous efforts in this area, the simulation model is built on the platform of a mesoscopic traffic simulation model, which allows modeling of the operations of large-scale transit systems. A Tel-Aviv case study demonstrates the transit simulation capabilities of the model.

  • 7.
    Burghout, Wilco
    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.
    Koutsopoulos, Haris
    Northeastern University.
    Vehicle loading in traffic simulation models2007In: Proceedings of the 86th Transportation Research Board Annual Meeting, 2007Conference paper (Refereed)
    Abstract [en]

    Microscopic traffic simulation models are becoming increasingly popular and used to address a wide range of problems, from planning to operations. Furthermore, hybrid models that combine mesoscopic and microscopic models to simulate large scale networks are emerging. Despite the significant progress though, a potentially important process, the loading of vehicles onto the network, has not received much attention. If vehicles are assigned their initial speeds improperly, especially in congested networks, unnecessary turbulence may be created that will result in artificially reduced capacity of the loading link. The paper reviews existing loading methods (employed by the state of the art models MITSIMLab and VISSIM) and demonstrates the sensitivity of the simulation results to the initial speed. The results show that loading has a significant effect on the initial acceleration behavior of the loaded vehicles, and the (implied) capacity of the first segment of the entry link. The paper proposes four alternative loading approaches and identifies one as theoretically sound and consistent. A case study demonstrates that the new method is robust, and performs well even under congested conditions. The proposed method is useful not only for loading vehicles in microscopic models but also in the context of hybrid models for transferring vehicles from the meso to the micro network.

  • 8.
    Burghout, Wilco
    et al.
    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 Science, Traffic and Logistics.
    Koutsopoulos, Haris
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Andreasson, Ingmar
    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 Science, Traffic and Logistics.
    A Discrete-Event Mesoscopic Traffic Simulation Model for Hybrid Traffic Simulation2006In: IEEE Intelligent Transportation Systems Conference, 2006. ITSC'06, IEEE , 2006, p. 1102-1107Conference paper (Refereed)
    Abstract [en]

    The paper presents a mesoscopic traffic simulation model, particularly suited for the development of integrated meso-micro traffic simulation models. The model combines a number of the recent advances in simulation modeling, such as discrete-event time resolution and combined queue-server and speed-density modeling, with a number of new features such as the ability to integrate with microscopic models to create hybrid traffic simulation. The ability to integrate with microscopic models extends the area of use to include evaluation of ITS systems, which often require the detailed modeling of vehicles in areas of interest, combined with a more general modeling of large surrounding areas to capture network effects of local phenomena. The paper discusses the structure of the model, presents a framework for integration with micro models, and illustrates its validity through a case study with a congested network north of Stockholm. It also compares its performance with a hybrid model applied to the same network.

  • 9.
    Burghout, Wilco
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Koutsopoulos, Haris
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Andreasson, Ingmar
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Incident Management and Traffic Information: Tools and Methods for Simulation-Based Traffic Prediction2010In: TRB 89th Annual Meeting Compendium of Papers,, 2010Conference paper (Refereed)
  • 10.
    Burghout, Wilco
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Rigole, Pierre Jean
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Andreasson, Ingmar
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Impacts of Shared Autonomous Taxis in a Metropolitan Area2015In: Proceedings of the 94th annual meeting of the Transportation Research Board, Washington DC, 2015Conference paper (Refereed)
    Abstract [en]

    The purpose of this paper is to provide an analysis of potential benefits of a fleet of shared autonomous taxis “aTaxis”, in this paper referred to as Shared Autonomous Vehicles  (SAV)) when replacing private car commuter trips in a metropolitan area. We develop a framework for dynamic allocation of SAVs to passenger trips, empty-vehicle routing and multi-criteria evaluation with regard to passenger waiting time, trip times and fleet size. Using a dynamic representation of current private vehicle demand for the Stockholm metropolitan area and a detailed network representation, different scenarios (varying levels of accepted passenger waiting time at origin and accepted % increase in travel time) are compared with respect to passenger travel time, number of vehicles needed and vehicle mileage. The results indicate that an SAV-based personal transport system has the potential to provide an on-demand door-to-door transport with a high level of service, using 5 % of today's private cars and parking places. In order to provide an environmental benefit and to reduce total mileage, an SAV-based personal transport system requires users to accept ride-sharing, allowing a maximum 30% increase of their travel time (13% on average) and a start time window of 10 minutes.

  • 11. Börjesson, M.
    et al.
    Dillén, J.
    Lind, G.
    Avery, Ryan P.
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Burghout, Wilco
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Trut - information search cost and benefits of traffic information (sweden)2008In: World Congr. Intell. Transp. Syst. ITS Am. Annu. Meet., 2008, p. 6685-6688Conference paper (Refereed)
    Abstract [en]

    Benefits from traffic information examined using three methods; focus groups, stated preference-studies (SP) as well as simulated work-trips on the internet. The SP-results show that that there is a clear relationship between message content and the valuation. They also show that the value of decreasing uncertainty, when informed about a travel time delay with ± 10 minutes, corresponds to SEK 3.80 (EUR 0.4). The travel simulation shows that radio messages in general have a larger effect than VMS messages on route choice. Repeated information has however an impact, since a large share of the respondents who did not switch route at the first decision point, switched at the next decision point where updated information was given.

  • 12.
    Börjesson, Maria
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Transport Studies, CTS.
    Harry, Flam
    Mörth, Ulrika
    Jan-Eric, Nilsson
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR. VTI.
    Infrastrukturbeslut måste grundas på samhällsekonomiska kalkyler: DN Debatt2016In: Dagens nyheter, ISSN 1101-2447, no 2016-02-17Article, book review (Other (popular science, discussion, etc.))
  • 13.
    Cats, Oded
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Dynamic Modelling of Transit Operations and Passenger Decisions2011Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Efficient and reliable public transport systems are fundamental in promoting green growth developments in metropolitan areas. A large range of Advanced Public Transport Systems (APTS) facilitates the design of real-time operations and demand management. The analysis of transit performance requires a dynamic tool that will enable to emulate the dynamic loading of travelers and their interaction with the transit system.

    BusMezzo, a dynamic transit operations and assignment model was developed to enable the analysis and evaluation of transit performance and level of service under various system conditions and APTS. The model represents the interactions between traffic dynamics, transit operations and traveler decisions. The model was implemented within a mesoscopic traffic simulation model. The different sources of transit operations uncertainty including traffic conditions, vehicle capacities, dwell times, vehicle schedules and service disruptions are modeled explicitly.

    The dynamic path choice model in BusMezzo considers each traveler as an adaptive decision maker. Travelers’ progress in the transit system consists of successive decisions that are defined by the need to choose the next path element. The evaluations are based on the respective path alternatives and their anticipated downstream attributes. Travel decisions are modeled within the framework of discrete random utility models. A non-compensatory choice-set generation model and the path utility function were estimated based on a web-based survey.

    BusMezzo enables the analysis and evaluation of proactive control strategies and the impacts of real-time information provision. Several experiments were conducted to analyze transit performance from travelers, operator and drivers perspectives under various holding strategies. This analysis has facilitated the design of a field trial of the most promising strategy. Furthermore, a case study on real-time traveler information systems regarding the next vehicle arrival time investigated the impacts of various levels of coverage and comprehensiveness. As passengers are more informed, passenger loads are subject to more fluctuation due to the traveler adaptations.

  • 14.
    Cats, Oded
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Effektivisering av busstrafik genom BuzMezzo2012Conference paper (Refereed)
  • 15.
    Cats, Oded
    et al.
    Faculty of Civil and Environmental Engineering, Technion-Israel Institute of Technology, Haifa.
    Burghout, Wilco
    KTH, School of Architecture and the Built Environment (ABE), Transport and Economics (closed 20110301), Traffic and Logistics (closed 20110301). KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Toledo, Tomer
    Koutsopoulos, Harilaos
    KTH, School of Architecture and the Built Environment (ABE), Transport and Economics (closed 20110301), Traffic and Logistics (closed 20110301).
    Mesoscopic Modeling of Bus Public Transportation2010In: Transportation Research Record, ISSN 0361-1981, E-ISSN 2169-4052, no 2188, p. 9-18Article in journal (Refereed)
    Abstract [en]

    Analysis of public transport system performance and level of service in urban areas is essential. Dynamic modeling of traffic conditions, passenger demand, and transit operations is important to represent adequately the complexity of and the interactions between these components in modern public transportation systems. 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. Unlike most previous efforts in this area, the simulation model is built on a platform of a mesoscopic traffic simulation model, which allows modeling or the operation dynamics of large-scale transit systems, taking into account the main sources of service uncertainty and stochasticity. 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 metropolitan Tel Aviv, Israel, under various scenarios. The application shows that important phenomena such as bus bunching are reproduced realistically. A comparison of simulated running times and headway distributions with field data shows the model is capable of replicating observed data.

  • 16.
    Cats, Oded
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    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 Science, Traffic and Logistics.
    Toledo, Tomer
    Koutsopoulos, Haris
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Effect of real-time transit information on dynamic passenger path choice.2011In: Transportation Research Record, ISSN 0361-1981, Vol. 2217, p. 46-54Article in journal (Refereed)
    Abstract [en]

    Real-time information is increasingly being implemented in transit networks worldwide. The evaluation of the effect of real-time information requires dynamic modeling of transit operations and of passenger path choices. This paper presents a dynamic transit analysis and evaluation tool that represents time-tables, operation strategies, real-time information, adaptive passenger choices, and traffic dynamics at the network level. Transit path choices are modeled as a sequence of boarding, walking and alighting decisions that passengers undertake when carrying out their journey. The model is applied to the Metro network of Stockholm, Sweden area under various operating conditions and information provision scenarios, as a proof of concept. An analysis of the results indicates substantial path choice shifts and potential time savings associated with more comprehensive real-time information provision and transfer coordination improvements.

  • 17.
    Cats, Oded
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    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 Science, Traffic and Logistics.
    Toledo, Tomer
    Koutsopoulos, Haris
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Evaluation of real-time holding strategies for improved bus service reliability2010In: IEEE Conference on Intelligent Transportation Systems, Proceedings, ITSC, Madeira, Portugal, 2010, p. 718-723Conference paper (Refereed)
    Abstract [en]

    Service reliability is one of the main measures of performance determining transit system level of service. Holding control strategies are a common transit operations practice aimed to reduce transit service unreliability by setting criteria for departure fromtime point stops. In order to adequately analyze the sources of uncertainty involved with transit performance, it is essential to model dynamically the interactions between traffic conditions, passenger demand and transit operations. BusMezzo, a transit simulation model has been developed on a platform of a mesoscopic traffic simulation model, which enables the representation of large-scale transit systems. The model implements severalreal-time holding strategies. It is used to evaluate the application of these strategies in areal-world high-demand bus line in the Tel Aviv metropolitan area, under various scenarios. An analysis of the results suggests that a holding strategy based on the mean headway from the preceding bus and the next bus, restricted by a maximum allowableholding time, is especially efficient. 

  • 18.
    Cats, Oded
    et al.
    Faculty of Civil and Environmental Engineering, Technion-Israel Institute of Technology, Haifa.
    Burghout, Wilco
    KTH, School of Architecture and the Built Environment (ABE), Transport and Economics (closed 20110301), Traffic and Logistics (closed 20110301). KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Toledo, Tomer
    Koutsopoulos, Haris
    KTH, School of Architecture and the Built Environment (ABE), Transport and Economics (closed 20110301), Traffic and Logistics (closed 20110301).
    Mesoscopic modeling of bus public transportation2010Conference paper (Refereed)
  • 19.
    Cats, Oded
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Burghout, Wilco
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Toledo, Tomer
    Technion - Israel Institute of Technology.
    Koutsopoulos, Haris N.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport and Location Analysis.
    Modeling real-time transit information and its impacts on travelers’ decisions2012In: Proceedings of the Transportation Research Board 91st Annual Meeting., 2012Conference paper (Refereed)
  • 20.
    Cats, Oded
    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.
    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 Science, Traffic and Logistics.
    Toledo, Tomer
    Evaluating the role of real-time transit information provision on dynamic passenger path choice2012In: Transportation Research Record, ISSN 0361-1981, E-ISSN 2169-4052Article in journal (Refereed)
  • 21.
    Cats, Oded
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Larijani, Anahid
    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.
    Burghout, Wilco
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Impacts of holding control strategies on transit performance: A bus simulation model analysis2011In: Transportation Research Record, ISSN 0361-1981, E-ISSN 2169-4052, no 2216, p. 51-58Article in journal (Refereed)
    Abstract [en]

    Transit operators are interested in strategies to improve service reliability as it is an important measure of performance and level of service. One of the common practices aimed at reducing service unreliability is holding control strategies. The design of these strategies involves the selection of a set of time point stops and the holding criteria for regulating the departure time. The interactions between passenger activity, transit operations, and traffic dynamics must be dynamically modeled to analyze the impacts of holding strategies on transit performance. An evaluation of different holding criteria and the number and location of time point stops was conducted with Bus Mezzo, a dynamic transit simulation model. The holding strategies were implemented in the model and applied to a high-frequency trunk bus line in Stockholm, Sweden. The analysis of the results considers the implications of holding strategies from both passenger and operator perspectives. The analysis suggests substantial gains are possible by implementing a holding strategy on the basis of the mean headway from the preceding and the succeeding buses. This strategy is the most efficient for passenger time savings as well as fleet costs and crew management.

  • 22.
    Cats, Oded
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Larijani, Anahid Nabavi
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Ólafsdóttir, Ásdís
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Burghout, Wilco
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Andréasson, Ingmar J.
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Koutsopoulos, Harilaos N.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Bus-Holding Control Strategies Simulation-Based Evaluation and Guidelines for Implementation2012In: Transportation Research Record, ISSN 0361-1981, E-ISSN 2169-4052, no 2274, p. 100-108Article in journal (Refereed)
    Abstract [en]

    Transit operations involve several inherent sources of uncertainty, including dispatch time from the origin terminal, travel time between stops, and dwell time at stops. Bus-holding control strategies are a prominent method applied by transit operators to improve transit performance and level of service. The common practice is to regulate departures from a limited number of stops by holding buses until their scheduled departure time. An analysis of the performance of a high-frequency bus line in Stockholm, Sweden, based on automatic vehicle location data showed that this control strategy was not effective in improving service regularity along the line. The analysis also indicated that drivers adjusted their speed according to performance objectives. Implications of a control strategy that regulates departures from all stops on the basis of the headways of the preceding bus and the following bus were evaluated with Bus Mezzo, a transit operations simulation model. The results suggest that this strategy can improve service performance considerably from both passengers' and operator's perspectives. In addition, the strategy implies cooperative operations, as the decisions of each driver are interdependent with other drivers' decisions, and mutual corrections can be made. Difficulties in realizing the benefits of the proposed strategy in practice, such as dispatching from the origin terminal, driver scheduling, and compliance, are discussed. The implications of several practical considerations are assessed by conducting a sensitivity analysis as part of the preparations for a field experiment designed to test the proposed control strategy.

  • 23.
    Cats, Oded
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Reimal, Triin
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Susilo, Yusak
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport and Location Analysis. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Public Transport Pricing Policy Empirical Evidence from a Fare-Free Scheme in Tallinn, Estonia2014In: Transportation Research Record, ISSN 0361-1981, E-ISSN 2169-4052, no 2415, p. 89-96Article in journal (Refereed)
    Abstract [en]

    Cities worldwide are looking for new policies to attract travelers to shift from cars to public transport. Policies focused on reducing public transport fares are aimed at improving social inclusion and leading to a modal shift. The City of Tallinn, the capital of Estonia, has recently introduced a fare-free public transport (FFPT) service in an effort to improve accessibility and mobility for its residents. The case of Tallinn is a full-scale, real-world experiment that provides a unique opportunity for investigating the impacts of FFPT policy. A macrolevel empirical evaluation of FFPT impacts on service performance, passenger demand, and accessibility for various groups of travelers is presented. In contrast to previous studies, the influence of FFPT on passenger demand was estimated while changes in supply were controlled. The results indicate that the FFPT measure accounts for an increase of 1.2% in passenger demand, with the remaining increase attributed to an extended network of public transport priority lanes and increased service frequency. The relatively small effect could be attributed to the previous price level and public transport share as well as analysis of the short-term impact. The evidence-based policy evaluation in this paper is instrumental in supporting policy making and facilitating the design of public transport pricing strategies.

  • 24.
    Cats, Oded
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Transport Studies, CTS. Delft Univ Technol, Dept Transport & Planning, 5048, NL-2600 GA Delft, Netherlands.;KTH Royal Inst Technol, Dept Transport Sci, Teknikringen 10, S-11428 Stockholm, Sweden..
    Susilo, Yusak O.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, System Analysis and Economics.
    Reimal, Triin
    Ramboll AB, Krukmakargatan 21, S-10462 Stockholm, Sweden..
    The prospects of fare-free public transport: evidence from Tallinn (vol 44, pg 1083, 2017)2018In: Transportation, ISSN 0049-4488, E-ISSN 1572-9435, Vol. 45, no 5, p. 1601-1602Article in journal (Refereed)
  • 25. Ekström, J.
    et al.
    Engelson, Leonid
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Rydergren, C.
    Heuristic algorithms for a second-best congestion pricing problem2009In: Netnomics, ISSN 1385-9587, E-ISSN 1573-7071, Vol. 10, no 1, p. 85-102Article in journal (Refereed)
    Abstract [en]

    Designing a congestion pricing scheme involves a number of complex decisions. Focusing on the quantitative parts of a congestion pricing system with link tolls, the problem involves finding the number of toll links, the link toll locations and their corresponding toll level and schedule. In this paper, we develop and evaluate methods for finding the most efficient design for a congestion pricing scheme in a road network model with elastic demand. The design efficiency is measured by the net social surplus, which is computed as the difference between the social surplus and the collection costs (i.e. setup and operational costs) of the congestion pricing system. The problem of finding such a scheme is stated as a combinatorial bi-level optimization problem. At the upper level, we maximize the net social surplus and at the lower level we solve a user equilibrium problem with elastic demand, given the toll locations and toll levels, to simulate the user response. We modify a known heuristic procedure for finding the optimal locations and toll levels given a fixed number of tolls to locate, to find the optimal number of toll facilities as well. A new heuristic procedure, based on repeated solutions of a continuous approximation of the combinatorial problem is also presented. Numerical results for two small test networks are presented. Both methods perform satisfactorily on the two networks. Comparing the two methods, we find that the continuous approximation procedure is the one which shows the best results.

  • 26. Ekström, J.
    et al.
    Rydergren, C.
    Engelson, Leonid
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    A heuristic method for finding congestion pricing schemes in traffic networks with modal choice2008In: Proceedings of the 13th International Conference of Hong Kong Society for Transportation Studies: Transportation and Management Science, 2008, p. 773-782Conference paper (Refereed)
    Abstract [en]

    In this paper we extend a previously developed heuristic procedure, with a modal choice model, to solve the congestion pricing problem of simultaneously finding the optimal number of toll facilities, their corresponding location and toll levels. When considering a congestion pricing scheme the cost of collecting the tolls can not be disregarded. The objective is wherefore to maximize the net social surplus, which is the social surplus minus the cost of collecting the tolls. The heuristic method is an iterative solution procedure, in which the integer part of the objective function is approximated by a continuous function. A version of the Sioux Falls network (76 links) is used to demonstrate the solution procedure. The solution is a congestion pricing scheme which divide the network into four zones, by locating tolls on 27 links. This solution yields a social surplus which is only 13.5% lower than the marginal social cost pricing solution.

  • 27. Ekström, Joakim
    et al.
    Engelson, Leonid
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport and Location Analysis. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Rydergren, Clas
    Optimal toll locations and toll levels in congestion pricing schemes: a case study of Stockholm2014In: Transportation planning and technology (Print), ISSN 0308-1060, E-ISSN 1029-0354, Vol. 37, no 4, p. 333-353Article in journal (Refereed)
    Abstract [en]

    As congestion pricing has moved from theoretical ideas in the literature to real-world implementation, the need for decision support when designing pricing schemes has become evident. This paper deals with the problem of finding optimal toll levels and locations in a road traffic network and presents a case study of Stockholm. The optimisation problem of finding optimal toll levels, given a predetermined cordon, and the problem of finding both optimal toll locations and levels are presented, and previously developed heuristics are used for solving these problems. For the Stockholm case study, the possible welfare gains of optimising toll levels in the current cordon and optimising both toll locations and their corresponding toll levels are evaluated. It is shown that by tuning the toll levels in the current congestion pricing cordon used in Stockholm, the welfare gain can be increased significantly, and furthermore improved by allowing a toll on a major bypass highway. It is also shown that, by optimising both toll locations and levels, a congestion pricing scheme with welfare gain close to what can be achieved by marginal social cost pricing can be designed with tolls being located on only a quarter of the tollable links.

  • 28.
    Engelson, Leonid
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport and Location Analysis. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Transport Studies, CTS.
    Burghout, Wilco
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Jonsson, Daniel
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport and Location Analysis. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Transport Studies, CTS.
    Integration of travel demand model with dynamic traffic assignment2012Conference paper (Refereed)
  • 29.
    Eriksson, B.
    et al.
    Karolinska Inst, Dept Neurobiol Care Sci & Soc NVS, Div Family Med, Huddinge, Sweden..
    Wandell, P.
    Karolinska Inst, Div Family Med, NVS, Solna, Sweden..
    Dahlstrom, U.
    Linkoping Univ, Dept Cardiol, Linkoping, Sweden.;Linkoping Univ, Dept Med & Hlth Sci, Linkoping, Sweden..
    Näsman, Per
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Transport Studies, CTS. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Lund, L. H.
    Karolinska Univ Hosp, Karolinska Inst, Dept Med, Unit Cardiol, Stockholm, Sweden..
    Edner, M.
    Karolinska Inst, Dept Med, Cardiol Unit, N3 06, Stockholm, Sweden.;Univ Hosp, Stockholm, Sweden..
    Comorbidities, risk factors and outcomes in patients with heart failure and an ejection fraction of more than or equal to 40% in primary care- and hospital care-based outpatient clinics2018In: Scandinavian Journal of Primary Health Care, ISSN 0281-3432, E-ISSN 1502-7724, Vol. 36, no 2, p. 207-215Article in journal (Refereed)
    Abstract [en]

    Objective: The aim of this study is to describe patients with heart failure and an ejection fraction (EF) of more than or equal to 40%, managed in both Primary- and Hospital based outpatient clinks separately with their prognosis, comorbidities and risk factors. Further to compare the heart failure medication in the two groups. Design: We used the prospective Swedish Heart Failure Registry to include 9654 out-patients who had HF and EF >= 40%, 1802 patients were registered in primary care and 7852 in hospital care. Descriptive statistical tests were used to analyze base line characteristics in the two groups and multivariate logistic regression analysis to assess mortality rate in the groups separately. Setting: The prospective Swedish Heart Failure Registry. Setting: The prospective Swedish Heart Failure Registry. Subjects: Patients with heart failure and an ejection fraction (EF) of more than or equal to 40%. Main outcome measures: Comorbidities, risk factors and mortality. Results: Mean-age was 77.5 (primary care) and 70.3 years (hospital care) p < 0.0001, 46.7 vs. 36.3% women respectively (p < 0.0001) and EF >= 50% 26.1 vs. 13.4% (p < 0.0001). Co-morbidities were common in both groups (97.2% vs. 92.3%), the primary care group having more atrial fibrillation, hypertension, ischemic heart disease and COPD. According to the multivariate logistic regression analysis smoking, COPD and diabetes were the most important independent risk factors in the primary care group and valvular disease in the hospital care group. All-cause mortality during mean follow-up of almost 4 years was 315% in primary care and 27.8% in hospital care. One year-mortality rates were 7.8%, and 7.0% respectively. Conclusion: Any co-morbidity was noted in 97% of the HF-patients with an EF of more than or equal to 40% managed at primary care based out-patient clinics and these patients had partly other independent risk factors than those patients managed in hospital care based outpatients clinics. Our results indicate that more attention should be payed to manage COPD in the primary care group.

  • 30. Fosgerau, Mogens
    et al.
    Engelson, Leonid
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    The value of travel time variance2011In: Transportation Research Part B: Methodological, ISSN 0191-2615, E-ISSN 1879-2367, Vol. 45, no 1, p. 1-8Article in journal (Refereed)
    Abstract [en]

    This paper considers the value of travel time variability under scheduling preferences that are defined in terms of linearly time varying utility rates associated with being at the origin and at the destination. The main result is a simple expression for the value of travel time variability that does not depend on the shape of the travel time distribution. The related measure of travel time variability is the variance of travel time. These conclusions apply equally to travellers who can freely choose departure time and to travellers who use a scheduled service with fixed headway. Depending on parameters, travellers may be risk averse or risk seeking and the value of travel time may increase or decrease in the mean travel time.

  • 31. Grumert, Ellen
    et al.
    Ma, Xiaoliang
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Tapani, Andreas
    Effects of a Cooperative Variable Speed Limit System on Traffic Performance and Exhaust Emissions2013In: TRB 92nd Annual Meeting Compendium of Papers, 2013Conference paper (Refereed)
    Abstract [en]

    Variable Speed Limit Systems (VSLS) where variable message signs show speed limits based on traffic or road conditions exist on motorways in many countries. The purpose of the VSLS is to decrease the number of accidents while increasing efficiency of traffic system. Cooperative systems are a type of intelligent transport system that has received increasing interest lately. The central part of a cooperative system is communication between vehicles and/or vehicles and the infrastructure. In this paper, a cooperative systems extension of a VSLS is proposed and evaluated by means of microscopic traffic simulation. In the proposed cooperative VSLS, communication between the vehicles and the infrastructure is made available via a roadside unit communicating the speed limits to vehicles upstream on the road. Both aggregate and micro-scale emission models are used to estimate emission from vehicle states in traffic flow. The results of the study show that the cooperative VSLS has a potential to contribute to flow harmonization and to reduce environmental impacts. The emission estimates in the study are dependent on the emission models being applied.

  • 32. Guan, Wei
    et al.
    Yan, Xuedong
    Radwan, Essam
    Wong, Sze Chun
    Ma, Xiaoliang
    KTH, School of Architecture and the Built Environment (ABE), Transport Science. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Advanced Dynamic Simulations in Transportation2015In: Discrete dynamics in nature and society, ISSN 1026-0226, E-ISSN 1607-887X, Vol. 2015, article id 675263Article in journal (Refereed)
  • 33. Gunay, B.
    et al.
    Akgol, K.
    Andreasson, Ingmar
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Terzi, S.
    Estimation of modal shift potential for a new form of dial-a-ride service2016In: Journal of Public Transportation, ISSN 1077-291X, Vol. 19, no 2, p. 75-88Article in journal (Refereed)
    Abstract [en]

    The concept of a dynamic and flexible Intelligent Subscription Bus Service (I-Service) was developed, and two integrated questionnaires were conducted among the commuters of a large university campus. To determine travel times to the campus by I-Service, a digital urban road network map with travel time databases was produced, and software was developed to calculate optimum routes using these databases. Travel times for each participant were determined by the shortest travel time principle. The proposed hypothetical service was introduced to participants, and anticipated advantages for each participant were reported back to them by means of a second questionnaire to determine if they would prefer using I-Service. As a result, a 49% modal shift potential from all other modes in general and a 52% modal shift potential from private car to I-Service were found.

  • 34.
    Huang, Zhen
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport and Economics (closed 20110301), Traffic and Logistics (closed 20110301).
    Ma, Xiaoliang
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Integration of Emission and Fuel Consumption Computing with Traffic Simulation using a Distributed Framework2009In: 2009 12TH INTERNATIONAL IEEE CONFERENCE ON INTELLIGENT TRANSPORTATION SYSTEMS (ITSC 2009), NEW YORK: IEEE , 2009, p. 154-159Conference paper (Refereed)
    Abstract [en]

    Air quality and fuel efficiency has become important factors in decision-makings on urban traffic planning and management. To support the process simulation models have potential to play essential roles in evaluation of planning alternatives and control strategies. However, traffic and its environmental impacts are different processes and often require various levels of models. With concerns on high computing performance and rich functionalities, it may be not appropriate to model emission inventory within traffic simulation. In this paper, we present a distributed simulation approach, and an independent emission/energy computing platform is built to simulate, visualize and analyze online emission outputs, given a microscopic traffic simulation tool, KTH-TPMA. Two distributed computing frameworks, common objects request broker architecture (CORBA) and service oriented architecture (SOA), are adopted in the distributed software design and implementation. Several emission models are implemented and generally evaluated in microsimulation runs of two road networks.

  • 35.
    Huang, Zhen
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Ma, Xiaoliang
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Koutsopoulos, Haris
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    A numerical optimization approach for calibration of dynamic emission models based on aggregate estimation of ARTEMIS2010In: IEEE Conference on Intelligent Transportation Systems, Proceedings, ITSC, 2010, p. 1221-1226Conference paper (Refereed)
    Abstract [en]

    In this paper, we propose a numerical approach to calibrate dynamic emission models when on-road or in-lab instantaneous emission measurements are not fully available. Microscopic traffic simulation is applied to generate dynamic vehicle states in the second-by-second level. Using aggregate estimation of ARTEMIS as a standard reference, a numerical optimization scheme on the basis of a stochastic gradient approximation algorithm is applied to find optimal parameters for the dynamic emission model. The calibrated model has been validated on several road networks with traffic states generated by the same simulation model. The results show that with proper formulation of the optimization objective function the estimated dynamic emission model can reasonably capture the trends of online emissions of traffic fleets.

  • 36. Jie, L.
    et al.
    Sen, C. Y.
    Hao, L.
    Andreasson, Ingmar
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Van Zuylen, H. J.
    Optimizing the fleet size of a personal rapid transit system: A case study in port of Rotterdam2010In: 2010 13th International IEEE Conference on Intelligent Transportation Systems (ITSC), IEEE , 2010, p. 301-305Conference paper (Refereed)
    Abstract [en]

    Cost issues have been an important concern in the development of Personal Rapid Transit (PRT) since the concept was developed several decades ago. The lightweight, computer-guided electric vehicles operating the PRT system are generally a major part of the capital cost of the system, especially in larger network with high demand. A sufficient number of empty vehicles are needed to be moved to the stations where passengers are waiting or demand is expected. Generally a larger fleet size leads to a reduction in waiting time of passengers and thus a higher level of service given a specific demand, but an increased investment cost including capital cost per vehicle and additional operation and maintenance. So it requires a compromise between user cost (in terms of passenger waiting times) and operator cost (in terms of fleet sizedependent capital cost and operating/maintenance costs). There should be an optimal fleet size so that the sum of these two costs can be minimized while an expected level of service is achieved. This paper presents first the way to obtain the PRT demand, and then a prescription to determine the optimal fleet size using a cost-effectiveness analysis with traffic simulation. This prescription identifies the set of activities that are necessary to perform the optimization task. Each activity is regarded as a component in our general framework and this framework is illustrated by a case study in the Waal/ Eemshaven harbor area in the Port of Rotterdam, The Netherlands.

  • 37. Johansson, I.
    et al.
    Edner, M.
    Ryden, L.
    Näsman, Per
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Dahlstrom, U.
    Norhammar, A.
    Impact of diabetes mellitus on long-term prognosis in patients with preserved heart failure: a report from the Swedish Heart Failure Registry (S-HFR)2014In: Diabetologia, ISSN 0012-186X, E-ISSN 1432-0428, Vol. 57, p. S25-S25Article in journal (Other academic)
  • 38. Kosonen, Iisakki
    et al.
    Ma, Xiaoliang
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    An Agent-base Traffic Signal Control System: Autonomous Features2013Conference paper (Refereed)
  • 39.
    Kristoffersson, Ida
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Congestion Charging in Urban Networks: Modelling Issues and Simulated Effects2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    One of the major challenges cities face today, in their development towards sustainable urban areas, is the need for an efficient and environmentally friendly transport system. This transport system should manage to tie together the city without strong adverse impact on urban environment, air-quality and climate change. The specialized labour (and leisure) market, typical of a large urban area, exaggerates the need for efficient travel, as it is increasingly difficult to live and work within short distances.   

    The use of demand management tools has become more frequent in transport planning with this development towards more sustainable cities. Whereas investing in new capacity was previously the main response to increased demand for travel, there is a much broader range of policies in use today. One of these demand management tools is congestion charging. Singapore was first to implement congestion charging and during the last decade it was followed by London and Stockholm, with increasing support from the citizens as a consequence. Many other cities have performed feasibility studies for introduction of congestion charging. 

    The development of transport models for prediction of demand management tools, such as congestion charging, has however not been able to keep up with this change in kind of policy. Transport models that were developed for prediction and evaluation of infrastructure investments, such as new motorways, are often used to forecast effects of policies aimed at managing demand, which too often results in poor prediction.

    This thesis focuses on the needs for modelling of congestion charging. The state-of-practice models used before implementation in Singapore, London and Stockholm are reviewed, as well as more advanced dynamic models developed for prediction of congestion charging and other demand management tools. A number of gaps in the modelling of congestion charging are described and a new model called SILVESTER is developed, which closes some of these gaps. In particular, SILVESTER involves dynamic mesoscopic modelling of traffic flows, flexible departure times and users with heterogeneous preferences.

    The thesis describes the implementation of SILVESTER and considers and compares different methods of demand aggregation in order to reduce run-time of the large-scale dynamic model (Paper I). It also describes how preferred departure times of road users can be determined in calibration such that consistency exists between the departure time choice model and dynamic traffic flows which are input to assignment (Paper II). The unique implementation of congestion charging in Stockholm gives the possibility to validate SILVESTER on real-world measurement of reductions in traffic flow and behavioural adjustments to the charges (Paper III). SILVESTER is then used to analyse several modified versions of the Stockholm congestion charging scheme and to compare welfare and equity effects of the different schemes. It is shown that the welfare of the current scheme could be improved if charges were allowed to differ by location and driving direction (Paper IV). It is shown that the benefits of congestion charges calculated using SILVESTER are greater than the benefits calculated with a static model. Finally, the reasons for the greater benefits are investigated (Paper V).

  • 40.
    Kristoffersson, Ida
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Impacts of time-varying cordon pricing: Validation and application of mesoscopic model for Stockholm2013In: Transport Policy, ISSN 0967-070X, E-ISSN 1879-310X, Vol. 28, no SI, p. 51-60Article in journal (Refereed)
    Abstract [en]

    This paper uses a simulation model to compare traffic and welfare effects of changes to the charging schedule currently in use in Stockholm. In particular, a step toll is compared to its flat counterpart at two charging levels. The increments between steps are also increased in a peaked step toll scenario. Furthermore, results from simulation of the current toll ring are compared to real-world measurements in a first attempt to validate model predictions regarding impacts of a time-varying congestion charging scheme. In the model, car users have the possibility to respond to congestion charging by changing departure time, route or switch to public transport and travel times are calculated using mesoscopic traffic simulation. Validation shows that departure time choice adjustments because of congestion charging are overestimated by the model that is based on stated preference data. This warrants further research on discrepancies between stated and revealed adjustments to congestion charging. The current step toll reaches the highest social benefit estimate in model predictions, but differences in traffic effects between the current step toll and its flat counterpart are rather small. Furthermore, results show that demand changes occur in the model to a considerably greater extent for trips with low value of time. The differences in welfare effects is for that reason large for different trip purposes, indicating the importance of accounting for heterogeneous trips when modelling effects of congestion charges.

  • 41.
    Kristoffersson, Ida
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Engelson, Leonid
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Alternative road pricing schemes and their equity effects: Results of simulations for Stockholm2011In: Proceedings of the TRB 90th Annual Meeting, Washington, D.C., 2011Conference paper (Refereed)
    Abstract [en]

    This paper uses a newly developed transport model to analyze effects of alternative road pricing schemes. The responses to road pricing included in the model are departure time, mode and route choice. Traffic analysis is performed on a large urban network of Stockholm using mesoscopic simulation. The compared pricing schemes differ in toll location and charged amount. Through calculation of consumer surplus per geographical zone, effects of the road pricing schemes are analyzed per income group and geographical area in order to study equity effects. Simulation results suggest that road pricing can be both regressive and progressive depending on the design of the pricing scheme, this even before the use of revenues to compensate users. Results also indicate that there can be a disagreement between which pricing scheme is preferable from a congestion mitigating point of view and which is preferable when looking at equity effects.

  • 42.
    Kristoffersson, Ida
    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.
    Engelson, Leonid
    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.
    Revealing Preferred Departure Times for Large-Scale Transport Modelling2008In: Proceedings of the 2008 International Symposium on Travel Demand Management, Vienna-Semmering, Austria, 2008Conference paper (Refereed)
  • 43.
    Langbroek, Joram Hendrik Maarten
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Franklin, Joel P.
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Transport Studies, CTS. KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, System Analysis and Economics.
    Susilo, Yusak
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Transport Studies, CTS. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR. KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, System Analysis and Economics.
    A stated adaptation instrument for studying travel patterns after electric vehicle adoption2018In: Transportation Research Procedia, ISSN 2324-9935, E-ISSN 2352-1465, Vol. 32, p. 464-473Article in journal (Refereed)
    Abstract [en]

    This paper describes and evaluates a stated adaptation instrument to investigate the effects of a transition towards electric vehicles on travel behaviour. The respondents were equipped with an “imaginary” electric vehicle with a specific range and were asked whether they wanted to make changes in an activity-travel schedule they had previously registered. It has been found that electric vehicle use may increase car use, and that activities are likely to be cancelled in case of problems with range limitations. In this paper, the validity, reliability and practical implementation of this stated adaptation experiment are discussed.

  • 44.
    Lei, Wei
    et al.
    Wuhan University of Technology.
    Ma, Xiaoliang
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Chen, Hui
    Wuhan University of Technology.
    Assessment of Traffic Environment using Fine-tuned Dynamic Vehicle Emission Models2010In: IEEE Conference on Intelligent Transportation Systems, Proceedings, ITSC, 2010, p. 1237-1242Conference paper (Refereed)
    Abstract [en]

    In order to assess environmental impacts of local traffic flow, a two-stage parameter tuning approach is proposed for recalibration of the Comprehensive Modal Emission Model (CMEM) using on-road emission measurements collected in Chinese cities. Based on the procedure comprising of grid search and nonlinear simplex optimization, the fuel- and emission-related parameters in the model are estimated to minimize the Mean Square Error (MSE) between model outputs and real measurements. In addition, a regression-based emission model is calibrated using the same data samples to compare performance. It is shown from the numerical results that the tuning process is able of improving the model prediction accuracy, especially concerning the CO emission, when comparing with the original CMEM model and the regression-based model. In addition, the emission models are, after the tuning process, applied together with a traffic simulation model to evaluate dynamic environmental effects of traffic in a case study.

  • 45. Liu, Chengxi
    et al.
    Susilo, Yusak
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Transport Studies, CTS. 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 Science.
    Karlström, Anders
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Transport Studies, CTS. KTH, School of Architecture and the Built Environment (ABE), Transport Science.
    Weather variability and travel behaviour - what we know and what we do not know2017In: Transport reviews, ISSN 0144-1647, E-ISSN 1464-5327, Vol. 37, no 6, p. 715-741Article in journal (Refereed)
    Abstract [en]

    Given that severe weather conditions are becoming more frequent, it is important to understand the influence of weather on an individual's daily activity-travel pattern. While some previously rare events are becoming more common, such as heavy rain, unpredicted snow, higher temperatures, it is still largely unknown how individuals will change and adapt their travel patterns in future climate conditions. Because of this concern, the number of research studies on weather and travel behaviour has increased in recent decades. Most of these empirical studies, however, have not used a cost-benefit analysis (CBA) framework, which serves as the the main tool for policy evaluation and project selection by stakeholders. This study summarises the existing findings regarding relationships between weather variability and travel behaviour, and critically assesses the methodological issues in these studies. Several further research directions are suggested to bridge the gap between empirical evidence and current practices in CBA.

  • 46.
    Ma, Xiaoliang
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    A computational model for driver-following behavior based on a neural-fuzzy system2007Report (Other academic)
  • 47.
    Ma, Xiaoliang
    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.
    A neural-fuzzy framework for modeling car-following behavior2006In: 2006 IEEE International Conference on Systems, Man and Cybernetics, Proceedings, IEEE , 2006, p. 1178-1183Conference paper (Refereed)
    Abstract [en]

    A general framework is introduced to model driver behavior from real car-following data acquired on Swedish roads using an advanced instrumented vehicle. In early research, the data was classified into different car-following regimes based on fuzzy clustering methods and knowledge obtained from video analysis. In this paper, we propose a multi-regime framework based on the statistical property in each regime and mathematical models adopted in those regimes. This framework is an extension of TSK fuzzy inference system and can be expressed by a Neural-Fuzzy system. Genetic Algorithm (GA) is designed as the main learning method for this system. In practice, this model structure illustrates human knowledge of car-following in a more understandable manner and can be rather flexible as the regime parameters and model forms may vary according to the application context.

  • 48.
    Ma, Xiaoliang
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Optimal Controls of Fleet Trajectories for Fuel and Emissions2013In: Proceedings of the IEEE Intelligent Vehicle Symposium (IEEE IV13), IEEE , 2013, p. 1059-1064Conference paper (Refereed)
    Abstract [en]

    Increased demand for transport, coupled with energy, climate and environmental concerns, has put more and more pressure for improved performance on traffic systems. The recent development in vehicle-to-infrastructure (V2I) communication provides an effective means for continuous management of vehicle driving. This study presents an essential step of the work towards a dynamic fleet management system that takes advantages of real-time traffic information and communication. Based on the optimal control theory, a methodological approach is developed to control the environmental impacts of live vehicle fleets. In particular, vehicle trajectories that minimize local environmental objectives are derived by applying a discrete dynamic programming method. Numerical examples show that the method is promising for local V2I based traffic management applications and can be further extended for more complex optimal control problems in dynamic fleet management.

  • 49.
    Ma, Xiaoliang
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Towards Intelligent Fleet Management: Local Optimal Speeds for Fuel and Emissions2013In: Proceedings of the 16th IEEE International Conference on Intelligent Transportation Systems (IEEE ITSC 2013), Den Haag, Netherland: IEEE conference proceedings, 2013Conference paper (Refereed)
    Abstract [en]

    In order to fulfill the policy requirements on increased transport energy efficiency and reduced emission impacts, smart control and management of vehicles and fleets have become important for the evolution of green intelligent transportation systems (ITS). The emergence of new information and communication technologies (ICT) and their applications, especially vehicle-to-vehicle and vehicle-to-infrastructure (V2I) communication, serves as an effective means for continuous management of real traffic fleet by providing vehicle driving support and guidance, and therefore affecting driver behavior. This study presents a recent Swedish R&D project for developing a dynamic fleet management system that incorporates real-time traffic information, eco-driving guidance and automated vehicle control in real-time heavy vehicle platooning. In addition to a general illustration of the main objectives of the project, the paper presents a methodological approach to developed local fleet control strategies so that the fuel and emissions of the managed vehicle fleet can be reduced. Speed trajectories minimizing predefined objectives are derived by applying a discrete dynamic programming method, and an instantaneous emission estimator is used for predicting fuel and emissions. Numerical examples show that the method is promising for real-time fleet management applications with support of V2I communication while the computational efficiency of the method needs to be enhanced. The adaptive speed control approach is implemented in a microscopic traffic simulation environment for further evaluation.

  • 50.
    Ma, Xiaoliang
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Andreasson, Ingmar
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Behavior measurement, analysis and regime classification in car following2007In: IEEE transactions on intelligent transportation systems (Print), ISSN 1524-9050, E-ISSN 1558-0016, Vol. 8, no 1, p. 144-156Article in journal (Refereed)
    Abstract [en]

    This paper first reports a data acquisition method that the authors used in a project on modeling driver behavior for microscopic traffic simulations. An advanced instrumented vehicle was employed to collect driver-behavior data, mainly car-following and lane-changing patterns, on Swedish roads. To eliminate the measurement noise in acquired car-following patterns, the Kalman smoothing algorithm was applied to the state-space model of the physical states (acceleration, speed, and position) of both instrumented and tracked vehicles. The denoised driving patterns were used in the analysis of driver properties in the car-following stage. For further modeling of car-following behavior, we developed and implemented a consolidated fuzzy clustering algorithm to classify different car-following regimes from the preprocessed data. The algorithm considers time continuity of collected driver-behavior patterns and can be more reliably applied in the classification of continuous car-following regimes when the classical fuzzy C-means algorithm gives unclear results.

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