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    Posts tagged modelling

    Operations of zero-emission buses: impacts of charging methods and mechanisms on costs and the level of service

    To limit global warming and strive for more liveable and sustainable cities, innovative zero-emission buses are on the rise all around the world. For now, only trolley, battery and fuel-cell electric vehicles can be classified as (on the pipe) zero-emission vehicles. Different charging methods, including different charging systems and power, are available to charge battery electric vehicles. However, scientific literature focused on the operation and charging scheduling of electric vehicles is scarce.
    In this study, a comparison of different applied charging methods for electric buses is obtained. A new ZE-bus station simulation method is developed to assess charging methods and charging regulations with regard to their impacts on costs and level of service.
    The shift to zero emission bus transport is meant for achieving more sustainable and liveable cities. However, this research concludes that this is involved with higher costs and passenger disturbances. The investment costs increase substantially. Benefits of electric operations, including vehicle propulsion cost savings up to 70 percent, are not able to compensate these high investments. (Slow) depot charging offers opportunities for operations on short distance lines. The depot location should be close to a bus station and additional fleet is required. In order to prevent fleet overcapacity, vehicles should be recharged with high charging power along the line, preferably at combined bus stations and terminals in order to prevent charging related delays. Dynamic/In-motion charging – still in its infancy stage yet – offers opportunities to prevent these delays due to combined charging and operation time.

    Find the TRB paper and poster of Max Wiercx HERE and HERE

    Robust Control for Regulating Frequent Bus Services: Supporting the Implementation of Headway-based Holding Strategies

    Reliability is a key determinant of the quality of a transit service. Control is needed in order to deal with the stochastic nature of high-frequency bus services and to improve service reliability. In this study, we focus on holding control, both schedule- and headway-based strategies. An assessment framework is developed to systematically assess the effect of different strategies on passengers, the operator and transport authority. This framework can be applied by operators and authorities in order to determine what holding strategy is most beneficial to regulate headways, and thus solve related problems. In this research knowledge is gained about what service characteristics affect the performance of holding strategies and the robustness of these strategies in disrupted situations, by using scenarios. The framework is applied to a case study of a high-frequency regional bus line in the Netherlands. Based on the simulation results, we identified the line characteristics that are important for the performance of schedule- and headway-based strategies and determined how robust different strategies are in case of disruptions. Headway-based control strategies better mitigate irregularity along the line, especially when there are disruptions. However, schedule-based control strategies are currently easier to implement, because it does not require large changes in practice, and the performance of both strategies is generally equal in regular, undisrupted situations. In this paper, insights into what the concerns are for operators with respect to technical adaptations, logistical changes and behavioral aspects when using a headway-based strategy are given.

    Find the TRB paper and presentation of Ellen van der Werff HERE and HERE

    E-bussen laden zorgt voor nieuw spanningsveld op busstations

    Om de bijdrage van transport aan de opwarming van de aarde te minimaliseren en de leefbaarheid in onze woonomgeving te verbeteren groeit de wereldwijde vloot zero-emissiebussen snel. Zero emissiebussen dragen bij aan een duurzame en leefbare woonomgeving. Uit dit onderzoek blijkt echter dat inzet van zero emissiebussen ook gepaard gaat met hogere kosten en meer onbetrouwbaarheid van de dienstregeling voor de reiziger. De investeringskosten zijn hoger dan bij ‘oude vertrouwde dieselbussen’. Exploitatie met elektrische bussen is tot 70% goedkoper dan dieselbussen, maar deze winst is niet genoeg om de toename in investeringskosten te neutraliseren. Tot op heden is de capaciteit van batterijen onvoldoende om bussen van begin tot einde dienst zonder tussentijds laden in te zetten. Tussentijds laden in de garage kost echter tijd en extra voertuigbewegingen en is daarom onwenselijk. Om die reden is het aan te raden batterijen te laden op busstations.

    Lees meer in het CVS paper met Max Wiercx en Raymond Huisman: Paper en Presentatie

    Driver schedule efficiency vs. public transport robustness: A framework to quantify this trade-off based on passive data

    More complex, efficient driver schedules reduce operator costs during undisrupted operations, but increase the disruption impact for passengers and operator once a disruption occurs. We develop an integrated framework to quantify the passenger and operator costs of disruptions explicitly as function of different driver schedule schemes. Since the trade-off between driver schedule efficiency and robustness can be quantified, this supports operators in their decision-making.

    Read the CASPT paper by Menno Yap HERE and find the presentation HERE

    Assessing disruption management strategies in rail-bound urban public transport from a passenger perspective

    This paper provides a framework for generating and assessing alternatives
    in case of disruptions in rail-bound urban public transport systems,. The proposed
    framework considers the passenger perspective as well as the operator perspective,
    for the often-used measures of detouring and short-turning. An application of the
    framework demonstrates that currently used disruption management protocols often
    do not lead to the optimal solution from the passenger perspective. Furthermore, the
    optimal choice between alternatives from passenger perspective shows to be
    dependent on the passenger flows.

    Read the CASPT paper HERE and find the presentation HERE

    Passenger Route Choice and Assignment Model for Combined Fixed and Flexible Public Transport Systems

    The recent technological innovations have given rise to innovative mobility solutions. Public transport systems combining such services need novel models for the design of services. We develop a multimodal route choice and assignment model for combined use of line/schedule based public transport systems (fixed public transport) and demand responsive services (flexible public transport). The model takes into account the dynamic demand-supply interaction using an iterative learning model framework. Flexible public transport can be used to perform any part of the trip, ranging from a first/last mile service to an exclusive direct door-to-door connection. The developed model is implemented in an agent based simulation framework. The model is applied to the test network of Sioux Falls. Results, in terms of modal split, fleet utilization, and passenger waiting times are analysed for scenarios in which fixed and flexible public transport are offered as competing modes as well as potential complementing modes.

    Find the CASPT presentation HERE

    Assessing and improving operational strategies for the benefit of passengers in rail-bound urban transport systems

    Unplanned disruptions in transit can have consequent impacts on passengers. The more inconvenienced passengers are, the more likely operators will be negatively impacted. Yet so far, operators and researchers have addressed the rescheduling problem during disruptions mainly with a supply-side focus – timetable, crews and vehicles – and not with a passenger perspective. Urban rail transit particularly lacks insights in terms of passenger- focused rescheduling. Being able to assess the inconvenience experienced by passengers during disruptions compared with what they normally experience, and being able to compare how different rescheduling strategies affect them are therefore two major challenges.

    The framework developed in this study precisely aims at tackling 8 these challenges. A case study of the metro of Rotterdam is used to test the framework developed in this paper. Alternative strategies are developed focusing on the incident phase (from the beginning of the incident until its cause is resolved). The application of the framework reveals that a regularity-focused rescheduling strategy would be beneficial for high-frequency service users. Realistically, yearly savings could amount to around €900,000 in terms of societal passenger costs for the operator in the Rotterdam area alone. However, the omnipresence of the punctuality paradigm, through which most operators plan and analyze operations, makes the implementation of passenger-focused strategies a challenging task for traffic controllers. The results of the study are valuable for transit operators worldwide and the framework can provide insights to decision-makers on the performance of different strategies, bringing to light trade-offs between supply and passenger sides during disruptions.

    Read more of this research by Anne Durand: Paper TRB and Poster TRB

    Performance assessment of fixed and flexible public transport in a multi agent simulation framework

    The emergence of innovative mobility solutions that offer flexible transport services, is changing the way urban public transport systems will be designed. Such mobility solutions offer on demand transport services and hence can solve the problems inherent with traditional line based and schedule based public transport systems. It is essential to understand the dynamics of this new demand-supply market with co-existing and competing fixed and flexible public transport. However, the performance of the system comprising of users and transit services and the factors influencing them, have received limited attention in literature. In this paper a model is developed to analyse the system performance when the modes of fixed public transport and flexible public transport operate in competition. The model is implemented in the multi-agent simulation framework MATSim with dynamic assignment in which the users optimize their travel plan through iterative learning from the service experienced and altering their travel plan. The scenarios in which the flexible public transport offer private and shared services are considered. The system performance is analysed for varying fleet size of flexible public transport and ratio of cost of flexible to fixed public transport.

    Find the paper HERE

    Modelling Multimodal Transit Networks: Integration of bus networks with walking and cycling

    Demand for (public) transportation is subject to dynamics affected by technological, spatial, societal and demographic aspects. The political environment, together with financial and spatial constraints limit the possibilities to address transit issues arising from growing demand through the construction of new infrastructure. Upgrading of existing services and improving integration over the entire trip chain (including cycling) are two options that can address these transport issues. However, transport planners and transport service operators often fail to include the entire trip when improving services, as improvement is normally achieved through the adaptations of characteristics (e.g. speeds, stop distances) of the services.
    Our developed framework consists of two parts: one to assess the characteristics of the different bus services and their access and egress modes, and one to assess the effects of integration of these services, which includes the modelling and analysis in a regional transit model. The framework has successfully been applied to a case study showing that bus systems with higher frequencies and speeds can attract twice the amount of cyclists on the access and egress sides. It also shows that passengers accept longer access and egress distances with more positive characteristics of the bus service (higher speeds, higher frequencies).

    Find the presentation of Judith Brand at MT-ITS in Napoli HERE

    Find our paper HERE

    Optimization of a passenger railway transportation plan considering mobility flows and service quality

    This research focuses on designing transportation plan for SNCF Transilien (French railway
    operator for the Parisian suburban mass transit). The objective is to develop methods
    and decision support tools to propose a timetable adapted to the passenger demand in the
    Parisian mass transit system, including comfort and reliability criterias.
    This paper aims to present the first step of this research. We propose a graph theoretic
    ILP formulation for the Line Planning Problem, minimizing both travelers travel time and
    operating cost. We furthermore develop a multi-objective method to solve this problem.
    This method offers a pool of solutions in order to let the final designer choose the solution.
    We report computational results on real world instances provided from SNCF Transilien.

    Check the RAIL Lille paper of Lucile Brethome et al. HERE

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