A review on railway delay management

Public Transport https://doi.org/10.1007/s12469-020-00233-1 ORIGINAL PAPER A review on railway delay management Eva König1 Accepted: 20 February 2020 © The Author(s) 2020 Abstract Passengers traveling by train may need to change trains on their route. If the focal train of a passenger is late, the passenger might miss his connection and has to decide how to continue his trip. Delay management addresses the question whether the connecting train should wait (or not) for the delayed passengers. If the connecting train waits, delays would get transferred through the network. In literature, several works consider delays and their impact on railways and how to reschedule disturbed plans. We focus on works, aiming to minimize passenger inconvenience as it is done in delay management. In the last two decades, dozens of works considering the delay management problem have emerged, tackling the problem in different ways. In this paper, an overview on the existing literature is given, and a new classification is introduced. We provide a taxonomy scheme for railway problems at an operational level and show how the field of delay management fits to other parts of the planning process. Moreover, limitations of the delay management approaches are discussed and future research opportunities are suggested. Keywords Delay management · Railways · Operational problems · Review 1 Introduction The focus of this review is on delay management (DM) for railways. DM, which was introduced by Schöbel (2001) and Suhl et al. (2001), searches for the answer of the so-called wait-depart decision. Should a connecting train wait for a delayed feeder and propagate the delay in the network or depart on time so that transferring passengers will miss their connection? In the last two decades, dozens of works considering this problem have been published. Figure 1 illustrates the growth of new publications since 2001 (the numbers arise from the reviewed literature in this paper). The proposed models for DM range from simple rules of thumb to complete network optimizations. To the best of our knowledge, a survey on these models * Eva König ‑mannheim.de 1 University of Mannheim, Schloss, 68131 Mannheim, Germany 13 Vol.:(0123456789) E. König Fig. 1  Number of new publications per five year interval (with a shortened last interval) has been neglected so far. Furthermore, a distinction between DM and other related areas is missing. The operational problems are often summarized under the term real-time management (Lusby et al. 2011). DM can be seen as a strong tool to reduce delays for passengers. In several studies, the results under dispatching are compared with results where no dispatching at all was done. Usually mentioned as never wait strategy in literature, trains do not wait at all for each other. The never wait strategy performs weaker than applied dispatching, as can be seen in, e.g., Kliewer and Suhl (2011), Dollevoet et al. (2012, 2015), showing that there exists a considerable impact on delay reduction. In practice, such as, e.g., in Germany, statistics on the punctuality only refer to trains. While the punctuality level for long-distance trains amounts to around 80%, this indicator only accounts for non-canceled trains that suffer a delay smaller than 6 min (Die Welt 2018). The delay of passengers is not reported but passengers on a canceled train might be facing transfer problems and probably also delays. The same holds for the tolerance of small delays. They are not part of the statistic but in reality they may cause connection conflicts for passengers (Die Welt 2017). For railways, as service providers, a passenger-friendly dispatching might be worth further investigation. In 2017 a simulation tool, called PANDA (Rückert et al. 2017, see Sect. 3.2), was applied in a real-world project with Deutsche Bahn (DB), the German railway provider. The tool detects connection conflicts and simulates the consequences on the arrival delays of passengers to support dispatchers in their decision-making process (Deutsche Bahn 2017). Planning problems for railways are manifold, beginning with long-term problems, such as building new infrastructure, to very short-termed problems, e.g., making dispatching decisions (Lusby et al. 2011). We concentrate on the operational level where railway providers have to cope with daily disturbances. Thereby, the literature often distinguishes between small disturbances leading to delays of several minutes (maybe even hours) and large disruptions that will cause a temporary break-down of the system (see, e.g., Ghaemi et al. 2017). When coping with small delays, dispatchers can 13 A review on railway delay management set different goals. One goal is to return as fast as possible to the original schedule and avoid further delay propagation in the network. We call it the train perspective with the objective to minimize train delays. Another goal is to minimize delays for passengers, i.e., the passenger perspective, on which we concentrate. In this review, we give a comprehensive overview on DM literature but we do not claim completeness. Therefore, we explain the characteristics of DM and distinguish it from other research areas on the short-term level and show how the planning process of Lusby et al. (2011) can be adjusted to the new categories that have arisen. Then we review the literature in the field of DM by developing a taxonomy scheme for operational problems containing five different attributes. The train perspective is usually the goal in real-time rescheduling (RTR) where train delays are minimized. As we will see in Sect. 2.1, DM and RTR differ in several aspects. There exist numerous reviews on RTR, but most of them contain only a part of the DM literature or neglect it totally. The term RTR has a broad scope, sometimes covering all operational problems after any type of disturbance has occurred. This paper understands RTR as timetable rescheduling in case of small disturbances. In the following, we give a short overview on existing literature reviews in related areas. – The above-mentioned review of Lusby et al. (2011) tackles all planning problems over all levels in general and gives an overall view on the railway industry. DM or RTR are not mentioned as seperate classes. – Cacchiani et al. (2014) give a comprehensive overview on problems in railway real-time management. Some works in DM are mentioned, but they are described briefly and not the complete existing literature is considered. – The same holds for Fang et al. (2015) where all problems in rescheduling are addressed and compared with each other; its focus lies on solution methods. – In Lusby et al. (2018) a review on robustness in railway planning is presented, but DM is addressed only briefly. The major part is dedicated to robust timetabling. – Ghaemi et al. (2017) report about large disruptions and how to recover from them with rescheduling models. DM models are not considered. The paper is st (...truncated)