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  • 1.
    Ait Ali, Abderrahman
    et al.
    The Swedish National Road and Transport Research Institute (VTI), Stockholm, Sweden.
    Eliasson, Jonas
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    The value of additional data for public transport origin–destination matrix estimation2022In: Public Transport, ISSN 1866-749X, E-ISSN 1613-7159, Vol. 14, no 2, p. 419-439Article in journal (Refereed)
    Abstract [en]

    Passenger origin–destination data is an important input for public transport planning. In recent years, new data sources have become increasingly common through the use of the automatic collection of entry counts, exit counts and link flows. However, collecting such data can be sometimes costly. The value of additional data collection hence has to be weighed against its costs. We study the value of additional data for estimating time-dependent origin–destination matrices, using a case study from the London Piccadilly underground line. Our focus is on how the precision of the estimated matrix increases when additional data on link flow, destination count and/or average travel distance is added, starting from origin counts only. We concentrate on the precision of the most policy-relevant estimation outputs, namely, link flows and station exit flows. Our results suggest that link flows are harder to estimate than exit flows, and only using entry and exit data is far from enough to estimate link flows with any precision. Information about the average trip distance adds greatly to the estimation precision. The marginal value of additional destination counts decreases only slowly, so a relatively large number of exit station measurement points seem warranted. Link flow data for a subset of links hardly add to the precision, especially if other data have already been added.

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  • 2.
    Häll, Carl Henrik
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Andersson, Henrik
    Department of Industrial Economics and Technology Management, Norwegian University of Science and Technology.
    Lundgren, Jan T.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Värbrand, Peter
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    The Integrated Dial-a-Ride Problem2009In: Public Transport, ISSN 1866-749X, E-ISSN 1613-7159, Vol. 1, no 1, p. 39-54Article in journal (Refereed)
    Abstract [en]

    In this paper we present a formulation of the Integrated Dial-a-Ride (IDARP). This problem is to schedule dial-a-ride requests, where some part of each journey may be carried out by a fixed route service. The IDARP is a generalization of the Dial-a-Ride Problem. An arc-based formulation is proposed, and it is shown how the model can be made easier to solve by arc elimination, variable substitution and the introduction of subtour elimination constraints. Small instances of the IDARP can be solved using an exact solution method, and one such instance is studied. We also describe how input and output data can be created and visualized in a geographic information system.

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  • 3.
    Häll, Carl Henrik
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Högberg, Magdalena
    Astando AB, Stockholm, Sweden.
    Lundgren, Jan T.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    A modeling system for simulation of dial-a-ride services2012In: Public Transport, ISSN 1866-749X, E-ISSN 1613-7159, Vol. 4, no 1, p. 17-37Article in journal (Refereed)
    Abstract [en]

    We present a modeling system for simulation of dial-a-ride services. It can be used as a tool for understanding and study how different designs, and different ways to operate a dial-a-ride service, affect the performance and efficiency of the service. The system simulates the operation of a dynamic dial-a-ride service that operates with multiple fleets of vehicles with different capacities, schedules and depots. It can be used to investigate how the setting of service and cost parameters and the design of the service affect the total cost for the operator and level of service for the customer. We describe the different modules in the system and the possible uses of the system. A short simulation study is performed to exemplify how it can be used. In this study the effects of including costs for customer discomfort are evaluated.

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  • 4.
    Häll, Carl Henrik
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Lundgren, Jan T.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Voß, Stefan
    Institute of Information Systems, University of Hamburg, Hamburg, Germany.
    Evaluating the performance of a dial-a-ride service using simulation2015In: Public Transport, ISSN 1866-749X, E-ISSN 1613-7159, Vol. 7, no 2, p. 139-157Article in journal (Refereed)
    Abstract [en]

    In this paper we study the effects of changes to a paratransit system operated as a dynamic dial-a-ride service. The scheduling of requests is limited by time window constraints and maximum ride time constraints; costs for customer discomfort in form of waiting time and excess ride time are considered in the planning of the service. The parameters defining these constraints and costs are evaluated based on simulations of a real-world scenario. Several different criteria, both regarding customer level of service and operational costs, are used to evaluate the simulation results. By showing which parameters have a large impact on the different evaluation criteria, we can give guidelines to operators of public transport of how to design their dial-a-ride services. Numerical results are presented and from these results conclusions are drawn regarding which parameters are most important in dynamic dial-a-ride services.

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  • 5.
    Johansson, Fredrik
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Peterson, Anders
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Tapani, Andreas
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Local performance measures of pedestrian traffic2014In: Public Transport, ISSN 1866-749X, E-ISSN 1613-7159, Vol. 6, no 1-2, p. 159-183Article in journal (Refereed)
    Abstract [en]

    Efficient interchange stations, where travelers are changing lines and/or travel modes, are essential for the functionality of the whole public transport system. By studying pedestrian movements, the level of service and effectiveness imposed by the design of the interchange station can be evaluated. We address the problem by microsimulation, where a social force model is used for the phenomenological description of pedestrian interactions. The contribution of this paper is the proposal of measures describing the density, delay, acceleration and discomfort for pedestrian flows. Simulation experiments are performed for the movements in two canonical pedestrian areas, a corridor and a corridor intersection. Clearly, each of the four measures gives a description for how pedestrians impede each other, and hence for the efficiency at the facility. There is, however, different information provided by each measure, and we conclude that they all are well-motivated for quantifying the level of service in a pedestrian flow. We also illustrate the outcome for a railway platform, with two trains arriving in parallel.

  • 6.
    Kecman, Pavle
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Goverde, R.M.P.
    Delft University of Technology, Delft, The Netherlands .
    Predictive modelling of running and dwell times in railway traffic2015In: Public Transport, ISSN 1866-749X, E-ISSN 1613-7159, Vol. 7, no 3, p. 295-319Article in journal (Refereed)
    Abstract [en]

    Accurate estimation of running and dwell times is important for all levels of planning and control of railway traffic. The availability of historical track occupation data with a high degree of granularity inspired a data-driven approach for estimating these process times. In this paper we present and compare the accuracy of several approaches to model running and dwell times in railway traffic. Three global predictive model approaches are presented based on advanced statistical learning techniques: LTS robust linear regression, regression trees and random forests. Also local models are presented for a particular train line, station or block section, based on LTS robust linear regression with some refinements. The models are validated and compared using a test set independent from the training set. The applicability of the proposed data-driven approach for real-time applications is proved by the accuracy of the obtained estimates and the low computation times. Overall, the local models perform best both in accuracy and computation time.

  • 7.
    Lidén, Tomas
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering. Swedish National Road and Transport Resarch Institute, Stockholm, Sweden.
    Coordinating maintenance windows and train traffic: a case study2020In: Public Transport, ISSN 1866-749X, E-ISSN 1613-7159, Vol. 12, no 2, p. 261-298Article in journal (Refereed)
    Abstract [en]

    This paper concerns a case study for optimal planning and coordination of railway maintenance windows and train traffic. The purpose is to validate a previously presented optimization model on a demanding real-life problem instance and to obtain results that apply in similar planning situations. A mixed integer linear programming model is used for a 913 km long, single-track railway line through the northern part of Sweden, with traffic consisting of 82 trains per day, most of which are freight trains. Cyclic 1-day schedules are produced, which show that 2 h long maintenance windows can be scheduled with small adjustments of the train traffic. The sensitivity for cost changes is studied, which shows that the train costs must increase by more than 30% in order to change the structure of the window solutions. Resource efficient window schedules are obtained by assigning maintenance teams to all windows while respecting crew work and rest time restrictions. A comparison with manually constructed plans from the Swedish Transport Administration indicates that larger window volumes can be scheduled at a lower cost and with solution structures which are deemed reasonable and useful as guidance for constructing the real window patterns. Finally, we estimate that using an integrated planning approach (where maintenance and trains are jointly planned) instead of a sequential approach (where a train timetable has precedence over the maintenance windows), will give maintenance cost savings of 11–17%, without incurring any large cost increases for the train traffic. The paper also presents a method for achieving cyclic schedules without any period-deciding variables, and discusses the consequences of the aggregated capacity usage model that has been adopted.

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  • 8.
    Ljunggren, Fredrik
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Persson, Kristian
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Peterson, Anders
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Schmidt, Christiane
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Railway timetabling: a maximum bottleneck path algorithm for finding an additional train path2021In: Public Transport, ISSN 1866-749X, E-ISSN 1613-7159, Vol. 13, p. 597-623Article in journal (Refereed)
    Abstract [en]

    We present an algorithm to insert a train path in an existing railway timetable close to operation, when we want to affect the existing (passenger) traffic as little as possible. Thus, we consider all other trains as fixed, and aim for a resulting train path that maximizes the bottleneck robustness, that is, a train path that maximizes the temporal distance to neighboring trains in the timetable. Our algorithm is based on a graph formulation of the problem and uses a variant of Dijkstra’s algorithm. We present an extensive experimental evaluation of our algorithm for the Swedish railway stretch from Malmö to Hallsberg. Moreover, we analyze the size of our constructed graph.

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  • 9.
    Posada, Marcus
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Andersson, Henrik
    Department of Industrial Economics and Technology Management, Norwegian University of Science and Technology, Trondheim, Norway.
    Häll, Carl Henrik
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    The integrated dial-a-ride problem with timetabled fixed route service2017In: Public Transport, ISSN 1866-749X, E-ISSN 1613-7159, Vol. 9, no 1-2, p. 217-241Article in journal (Refereed)
    Abstract [en]

    This paper concerns operational planning of door-to-door transportation systems for the elderly and/or disabled, who often need a more flexible transportation system than the rest of the population. Highly flexible, but very costly direct transportation is often offered as a complement to standard fixed route public transport service. In the integrated dial-a-ride problem (IDARP), these modes of transport are combined and certain legs of the passengers journeys may be performed with the fixed route public transport system. We extend the IDARP and include timetables for the fixed route services, forcing the fleet of vehicles to schedule the arrival at transfer locations with care. Two mixed integer linear programming formulations of the integrated dial-a-ride problem with timetables are presented and analyzed. The key modeling challenge is that of the transfers between the fleet of vehicles and the fixed route public transport system. The formulations differ in how the transfers are modeled and the differences are thoroughly discussed. The computational study compares the formulations in terms of network size, computational time and memory usage and conclusions about their performances are drawn.

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  • 10.
    Rydergren, Clas
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Comparison of headway-based public transport models: Numerical experiments for Stockholm2013In: Public Transport, ISSN 1866-749X, E-ISSN 1613-7159, Vol. 5, no 3, p. 177-191Article in journal (Refereed)
    Abstract [en]

    In this paper we evaluate the output from four headway-based public transport model variants for modeling the public transports in Stockholm, Sweden. The results from the four models are analyzed and compared to trip observations. The comparisons are based on model instances where the parameters in the generalized travel time function are calibrated. The best possible parameter values have been found using the calibration procedures SPSA and Compass search. Two different objective functions have been evaluated for the calibration.

    Numerical experiments have been performed using a public transport model implemented in Visum by Storstockholms lokaltrafik. For the calibration and analysis, trip observations from the Swedish national travel survey and data generated from a public transport trip planner are used.

    From the numerical results, it is concluded that it is of less importance to find the best possible parameter values in the generalized cost function than selecting the best model variant. For the Stockholm public transport model, the numerical results indicate that the models in the class of Random departure time models result in a better fit to the observed trips than the models in the class of Optimal strategies.

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