Railway line capacity consumption of different railway signalling systems under scheduled and disturbed conditions

Abstract

This paper evaluates the capacity consumption on a Dutch railway line both under scheduled and disturbed traffic conditions. For the scheduled condition the standard UIC compression method is used, while the computation of capacity consumption under disturbed conditions requires multiple simulation runs via a Monte Carlo simulation set up. For the analysis we use the optimization-based train dispatching system ROMA that combines the alternative graph formulation of train rescheduling with blocking time modelling of the signalling constraints. For this study ROMA is extended to various signalling/ATP systems so that the braking behaviour of hindered trains is accurately simulated in the different configurations. In addition, ROMA computes the compressed timetable with conflict-free train paths without rescheduling. For the disturbed scenarios, we consider a case study of the Utrecht-Den Bosch line equipped with different signalling/ATP systems. Two traffic control scenarios are considered for the disturbed scenarios: a first come first served rule and an advanced branch-and-bound algorithm. The results show that the scheduled capacity consumption improves from the Dutch NS’54/ATB to ETCS Level 2 with short blocks. In presence of delayed operations, the capacity consumption declines for NS’54/ATB, since trains have to brake and run at lower speeds. With ETCS, there is a considerable gain in terms of capacity consumption and punctuality compared to NS’54/ATB, since the braking distances decrease when delayed trains run at lower speeds, having a stabilizing effect on headway times, delay propagation and throughput.