Railway operations management must cope with failures of the railway system and with external disturbances that may cause initial delays, the so-called primary delays. In heavy traffic areas of railway networks, primary delays can quickly lead to many further delays, called secondary delays or knock-on delays. This paper describes the results of an experimental analysis which aims to evaluate the ability of railway traffic optimization tools to decrease secondary delays, by selecting appropriate route settings and sequences of train movements. We have previously proposed a mixed-integer linear programming (MILP) formulation to tackle this problem (Pellegrini, P., Marliere, G. and Rodriguez, J. 2013. Optimal train routing and scheduling for managing traffic perturbations in complex junctions, Transportation Research Part B: Methodological, to appear). This formulation considers a fine granularity of the infrastructure and it takes into account a large number of commercial and technical aspects characterizing real situations, e.g., passenger and rolling stock connections between trains, signal watching times, different numbers of signaling aspects, sectional route release of the interlocking systems. The experiments reported in this paper have been carried out in the context of the ON-TIME European project (http://www.ontime-project.eu/). This project aims to develop a prototype for a new generation of railway traffic management systems which will increase capacity and decrease delays, for augmenting customers' satisfaction. The results of the project will be validated through system simulation and real-life case studies proposed by different railway undertakings partners of the project.
At peak hours, railway timetables extensively exploit the infrastructure for accommodating traffic. Hence, the occurrence of unexpected events, even of apparently negligible entity, may cause a relevant deviation with respect to the scheduled timetable. If a train is delayed due to an unexpected event, conflicts may emerge, multiple trains may claim the same track section concurrently : in this case trains may have to stop or slow-down for ensuring safety and delay propagation may emerge. The selection of the train routing and scheduling for minimizing delay propagation has been formalized as the real-time Railway Traffic Management Problem (rtRTMP). In this study, we propose a fixed-speed mixed-integer linear programming formulation for optimally solving the rtRTMP. We model the infrastructure in terms of track-circuits, which are the basic components for train detection. In a thorough experimental analysis we quantify the improvement, in terms of reduction of delay propagation, that can be achieved by allowing the platform assignment to be different from the one defined in the timetable.
Railway operations management must cope with system failures and external disturbances that may cause delays. In heavy traffic areas, these delays can quickly propagate. This study details the results of a railway traffic optimization tool based on a MILP formulation. The case studies tackled represent different European locations. These experiments are part of a task the European FP7 project ON-TIME. The project aims to develop a prototype for a new generation of railway traffic management systems which will increase capacity and decrease delays for railway customers’ satisfaction.
Measuring capacity of railway infrastructures is an open problem even in its definition. In this paper, we propose RECIFE-SAT, a MILP-based algorithm to quantify capacity by solving the saturation problem. This problem consists in saturating an infrastructure by adding as many trains as possible to an existing (possibly empty) timetable. In an experimental analysis performed in collaboration with the French infrastructure manager, we show the promising performance of RECIFE-SAT. To the best of our knowledge, RECIFE-SAT is the first algorithm which is shown to be capable of saturating rather large railway networks considering a microscopic infrastructure representation. This representation allows RECIFE-SAT to really quantify the actual capacity of the infrastructure considered.
