Research Collection Journal Article Dynamic train unit coupling and decoupling at cruising speed Systematic classification, operational potentials, and research agenda Author(s): Nold, Michael; Corman, Francesco Publication Date: 2021-06 Permanent Link: https://doi.org/10.3929/ethz-b-000473438 Originally published in: Journal of Rail Transport Planning & Management 18, http://doi.org/10.1016/j.jrtpm.2021.100241 Rights / License: Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International This page was generated automatically upon download from the ETH Zurich Research Collection. For more information please consult the Terms of use. ETH Library Journal of Rail Transport Planning & Management 18 (2021) 100241 Contents lists available at ScienceDirect Journal of Rail Transport Planning & Management journal homepage: http://www.elsevier.com/locate/jrtpm Dynamic train unit coupling and decoupling at cruising speed: Systematic classification, operational potentials, and research agenda Michael Nold, Francesco Corman * Institute for Transport Planning and Systems, ETH Zürich, Switzerland ARTICLE INFO ABSTRACT Keywords: The possibility to couple train units into consists, which can be vehicles or platoons, has been Virtual coupling proposed to improve, among other, average passenger speed, energy efficiency, and railway Continuous railway system infrastructure capacity utilization. We systematically review and categorize the technologies and Dynamic coupling application of coupling train units into vehicles or platoons, identifying different generations of (Train) Unit coupling in operation train coupling, which are used for railway operations. The requirements, compatibility in terms of Dynamic mechanical coupling Portion working infrastructure and vehicle equipment as well as backward compatibility are analyzed. The po­ tential of a dynamic train unit coupling and decoupling at cruising speed is proposed, and identified as the 4th generation of train coupling. The possibility of current technology to implement a mechanical dynamic coupling and decoupling at cruising speed is reviewed, with functional requirements and steps of such a process. Based on dynamic coupling at cruising speed, various operating concepts are presented, with focus on commuter-networks between polycentric agglomerations. The potential of dynamic coupling and decoupling at cruising speed might reach travel time reductions in the order of 1/3 and no transfers, for a typical test case in Switzerland between Bern and Zurich. 1. Introduction Public transport networks, and railway in particular, provide mobility to everybody over a large set of origins and destinations interconnected into a network. A key limitation of public transport, and railway in specific, is its practical impossibility to econom­ ically and efficientlyconnect every starting point with every destination. The essence of a public transport system is the concentration of passenger flowsonto specificlines of movement (Nielsen and Lange, 2007). For this reason, railway transport is usually structured and bundled in lines along high quality routes, which are interconnected at stations or hubs. The lines might have different transport goals, for instance people usually have to transfer between a system with a high accessibility in space (and low speed) and a system with higher speed (but low accessibility in space). A network of lines interlinked and connected with each other enables a considerably larger number of connections between larger amount of origins and destinations, increases frequency of operations, and improves overall travel time (Van Nes, 1999). The amount of services running over each line is related to a maximum infrastructure capacity. In general it is well known that transferring between vehicles reduces the attractiveness for the passenger. In contrast, more direct connections increase the attractiveness of the transport system for passengers. The design of public transport networks strives to * Corresponding author. E-mail address: [email protected] (F. Corman). https://doi.org/10.1016/j.jrtpm.2021.100241 Received 9 June 2020; Received in revised form 12 February 2021; Accepted 19 February 2021 Available online 7 March 2021 2210-9706/© 2021 Published by Elsevier Ltd. M. Nold and F. Corman Journal of Rail Transport Planning & Management 18 (2021) 100241 provide high quality transfers, when possible (Nielsen and Lange, 2007). Given that railway frequencies are often lower than for urban public transport, the waiting time related to a transfer is typically larger. The elasticity of passenger demand to transfers has been identifiedempirically as very high. Empirical evidences include the case of Karlsruhe, where an urban railway system with transferless direct connection (tram-train) increased passenger demand by a factor of 4, and in the long term by a factor 9 (AVG, 2015). The Bayrische Oberlandbahn (south of Munich, Germany), increased passenger numbers by a factor of 3.3 through direct connections with portion working (we call portion working when two or more train units drive coupled together for a portion of a line; at a stop they split and continue independently on other lines) and usage of automatic couplers (Allianz pro Schiene, 2010). Similar portion working is used in a range of conventional and high speed services throughout the world. To improve railway services, more services can run on a section, larger volumes of demand can be transported. This reduces the fixed costs per service, and enables cheaper and more efficient operations. The bottleneck is the infrastructure capacity, i.e. the maximum amount of trains that can run in a unit of time. Due to the safety and signaling system standard in railway operations, vehicles are running in absolute braking distance (Hansen and Pachl, 2014), which identifiesa blocking time which is reserved for each vehicle running, depending on its speed, length, and signaling system characteristics. The blocking time limits the amount of vehicles that can run in a unit of time. Most railway mainlines are already saturated at bottlenecks, i.e. they cannot run more services per hour, unless technological (e.g., new signaling system, new signaling technology, improved dynamic characteristic) or infrastructure im- provements (e.g., more tracks) are made. Infrastructure capacity is related to the maximum passenger flow,i.e. amount of vehicles that can be moved per hour, multiplied by the amount of passenger space available within a vehicle (seating or standing). Having longer units travel through the bottleneck obviously improves the amount of passenger space available within each vehicle, at the expense of a slightly longer blocking time. In reality, the maximum allowed length of vehicles can be limited also by the signaling system, the available platform length at stations, length of the sidings, and some other operational and infrastructure factors. Demand of public transport systems is typically heterogeneous in space. In other terms, there are agglomerations, where most people live, which are separated by longer distances. Demand from the agglomeration can be both directed to another place within the agglomeration, typically a city center; or to other places in other agglomerations. Due to the generalized growth of cities, agglom- erations tend to develop into polycentric structures. This results in non-uniform utilization of vehicle and infrastructure capacity, when public transport services have to connect them. The resulting increases in costs for operators, and ultimately for users effectively obliges that not all possible origin destination can be served by direct services. Interconnection of services into networks enables a more balanced capacity utilization by means of hierarchical services, which are able to more flexiblyadjust to the different levels of demand. On the other hand, interconnection of services increases the inconvenience for passengers in terms of transfer and time lost when such an interconnection is effectively exploited. The key idea of coupling is to flexiblyadapt the vehicle capacity to various spatial requirements, by running longer vehicles, which have a higher passenger capacity per vehicle. By means of coupling, even small amount of demand can fitsmall units running from a large set of origins to a large set of destinations. When coupling takes place at stand still, there is an obvious increase in travel time, as stops and related braking and acceleration consume (relatively) large amount of time. We therefore investigate the concept of dynamic coupling, where coupling and decoupling might take place at non-zero speed (thus saving the extra stop to change composition). We investigate under which conditions this is beneficial, in order to balance various key performance indicators from operators and passenger side. With a goal of a general perspective, we discuss here the overarching terminology used in the paper throughout multiple gener- ations of coupling. When specificterms are accepted in the literature for a specificapplication, we might refer to those specificterms, as far as no ambiguity is present. We consider coupling in general as the usage of vehicle, infrastructure and communication technology by which wagons, locomotives, trains, Electric multiple units (EMUs) can be combined with each other. We call transport units or simply units, those wagons, locomotives, trains, EMUs (Vuchic, 2007). Each transport unit has the possibility to provide services to people