Dispatching and Rescheduling Tasks and Their Interactions with Travel Demand and the Energy Domain: Models and Algorithms

Abstract The paper aims to provide an overview of the key factors to consider when performing reliable modelling of rail services. Given our underlying belief that to build a robust simulation environment a rail service cannot be considered an isolated system, also the connected systems, which influence and, in turn, are influenced by such services, must be properly modelled. For this purpose, an extensive overview of the rail simulation and optimisation models proposed in the literature is first provided. Rail simulation models are classified according to the level of detail implemented (microscopic, mesoscopic and macroscopic), the variables involved (deterministic and stochastic) and the processing techniques adopted (synchronous and asynchronous). By contrast, within rail optimisation models, both planning (timetabling) and management (rescheduling) phases are discussed. The main issues concerning the interaction of rail services with travel demand flows and the energy domain are also described. Finally, in an attempt to provide a comprehensive framework an overview of the main metaheuristic resolution techniques used in the planning and management phases is shown

Smooth and controlled recovery planning of disruptions in rapid transit networks

This paper studies the disruption management problem of rapid transit rail networks. We consider an integrated model for the recovery of the timetable and the rolling stock schedules. We propose a new approach to deal with large-scale disruptions: we limit the number of simultaneous schedule changes as much as possible, and we control the length of the recovery period, in addition to the traditional objective criteria such as service quality and operational costs. Our new criteria express two goals: the recovery schedules can easily be implemented in practice, and the operations quickly return to the originally planned schedules after the recovery period. We report our computational tests on realistic problem instances of the Spanish rail operator RENFE and demonstrate the potential of this approach by solving different variants of the proposed model

Delays and Timetabling for Passenger Trains

Travel by train has increased steadily in Sweden the last 30 years. The pace has been about two to three percent per year, and we now have twice as many passengers. With growing awareness of the changing climate, the pace is increasing further. A problem that affects both passengers and businesses in Sweden is train delays. One way to describe these is as the share of trains that arrive less than six minutes delayed. About 90% of trains in Sweden meet this standard and have done so for many years. In a way this is impressive, since there are now many more trains. Unfortunately, this also means that more and more passengers are affected by delays. This leads to irritation, threatens the shift of traffic to railways, and costs a lot for society. More trains must arrive on time. This thesis shows that delays are mostly caused by small disturbances – up to a minute or two. Over long journeys, these small disturbances accumulate and sometimes cause quite big delays. These delays mostly occur at stations, where the trains stop, but are then unable to continue on time. It is difficult to say exactly what causes these small disturbances, but the time that the trains are supposed to be at stations – the dwell times – are often too short. Another pattern is seen between delays and weather: if it is either warm or cold, delays increase rapidly. And while winter and snow return every year, they still cause major disruptions. The thesis holds a few suggestions to reduce delays. One is platform markings that show where the trains will stop, where the doors will be, and where the passengers should wait. This is an easy and affordable way to speed up the stops, so that the trains depart on time. Another measure is to remove switches. Then there are fewer parts that can fail, and those that remain can be maintained to a higher standard. A third way is to adapt the railway, so that it better withstands the weather variations of today, and the climate changes of tomorrow. Something that has been done in other countries is to shade and air-condition electronics and signals along the railway. Then the components to not overheat, and more trains run on time. Many things can also be done with timetables, so that more trains run on time, without a rise in costs. More of the planning can be automated. Then more time can be spent on giving trains appropriate dwell times. Infrastructure managers should also do more to evaluate and improve the rules and guidelines that govern timetabling. In this way we can improve timetables gradually from year to year, with fewer and fewer delays as a consequence. These suggestions do not solve all of the railway’s issues, but they would lead to many more trains arriving on time

Shuttle Planning for Link Closures in Urban Public Transport Networks

Urban public transport systems must periodically close certain links for maintenance, which can have significant effects on the service provided to passengers. In practice, the effects of closures are mitigated by replacing the closed links with a simple shuttle service. However, alternative shuttle services could reduce inconvenience at a lower operating cost. This paper proposes a model to select shuttle lines and frequencies under budget constraints. We propose a new formulation that allows a minimal frequency restriction on any line that is operated and minimizes passenger inconvenience cost, which includes transfers and frequency-dependent waiting time costs. This model is applied to a shuttle design problem based on a real-world case study of the Massachusetts Bay Transportation Authority network of Boston, Massachusetts. The results show that additional shuttle routes can reduce passenger delay compared to the standard industry practice, while also distributing delay more equally over passengers, at the same operating budget. The results are robust under different assumptions about passenger route choice behavior. Computational experiments show that the proposed formulation, coupled with a preprocessing step, can be solved faster than prior formulations

User perspectives in public transport timetable optimisation

The present paper deals with timetable optimisation from the perspective of minimising the waiting time experienced by passengers when transferring either to or from a bus. Due to its inherent complexity, this bi-level minimisation problem is extremely difficult to solve mathematically, since timetable optimisation is a non-linear non-convex mixed integer problem, with passenger flows defined by the route choice model, whereas the route choice model is a non-linear non-continuous mapping of the timetable. Therefore, a heuristic solution approach is developed in this paper, based on the idea of varying and optimising the offset of the bus lines. Varying the offset for a bus line impacts the waiting time passengers experience at any transfer stop on the bus line.In the bi-level timetable optimisation problem, the lower level is a transit assignment calculation yielding passengers' route choice. This is used as weight when minimising waiting time by applying a Tabu Search algorithm to adapt the offset values for bus lines. The updated timetable then serves as input in the following transit assignment calculation. The process continues until convergence.The heuristic solution approach was applied on the large-scale public transport network in Denmark. The timetable optimisation approach yielded a yearly reduction in weighted waiting time equivalent to approximately 45 million Danish kroner (9 million USD)

The philosophy and practice of Taktfahrplan: a case-study of the East Coast Main Line.

Executive Summary This Working Paper has three purposes, represented by three Parts: - to explain the principles of the Taktfahrplan approach to railway timetabling; - to summarise the implications of the background research on the structure of the network; and - to describe the exercise of constructing a Taktfahrplan for the East Coast Main Line that formed the case-study of the potential benefits of such a scheme compared with the existing timetable. In Part I the broad principles and objectives are first outlined, and the advantages and disadvantages discussed [§ 1.1,1.2]. A Taktfahrplan is based on standard hours and the careful, network-wide coordination of sewices. It is recognised that ultimately the choice between this and conventional timetabling methods must depend on an evaluation of the loss of present flexibility to adjust to time-specific market demands against the gains from enhanced connectivity and from the fact of regularity. Issues concerning resources and the management of peak periods are also explained. Terminology is then dealt with because words and phrases are being used with imprecise and various meanings [§1.3]. There follows a detailed account of the arithmetic rules through which the ideal relationships between train (and bus) sewices can be attained, together with an explanation of the measures that can be taken to make the best compromises in the face of the characteristics of the real network - or to adjust it over time [§ 1.4]. In Part 2 the research to highlight features of the underlying demand for travel is described. This is not a necessary component of strategic timetable planning, but it is argued that it is desirable in order both to break free from the historical baggage and to seize the business, environmental and social-policy opportunities that a 'clean- sheet' timetable would present [§2.1]. The provisional findings from this work (it was left incomplete for reasons that are explained) are then deployed to form the skeleton of a national network connecting 100 important centres with 158 links. This is followed by an analysis of the very variable standards of the rail timetable on those links and of the road competition and by an account of some first thoughts as to how a full-scale Taktfahrplan might start to be developed on this network [§2.2]. This emphasises the inter-relationships between sewices and the inescapable consequences for pathing trains, once it is accepted that sensible spacing of services and striving for good connectivity are more important than optimising routes on a self-contained basis. It was thought appropriate to include a summary of the findings regarding the low-density end of the current rail system in order to indicate the issues that Taktfahrplan might raise in this respect [§2.3]. The East Coast case-study is presented in Part 3. Some technical matters are explained first, including the key point that the exercise used the Viriato timetabling software employed by the Swiss Federal Railways (and many other systems) to construct Taktfahrpliine [§3.1]. Successive sub-parts then describe groups of services: long-distance [§3.2], services within Scotland [§3.3], services in North East England [§3.4], the trans-Pennine network [§3.5] and some of the Yorkshire services [§3.6]