Simulation of different railway signalling systems

During multiple vehicle motion, the motion of each train depends on the position of the train ahead. A safety signalling system can be defined in terms of the behaviour of two adjacent trains. Although the rules of safety signalling are well established, there are a number of different approaches for its implementation. This paper presents the results of simulated train operation, controlled by different signalling systems. The difference between the signalling systems is based on how the safe distance separating the trains from each other is defined and calculated. The results of our study are obtained by application of the software package "Order Offer Headway Availability Analysis, version 1.36" (OOHAA), developed for Adtranz Sweden and aimed at simulations of mass transit systems. This paper describes an attempt to adapt the simulation tool to Study the capacity of a 139 km long section of a single railway main line in China. The benefit of OOHAA is to investigate and show how closely the trains can be run without restrictive messages from the signalling system. The differences between the two traffic environments of a mass transit system versus a railway main line are pointed out. The positions and situations at which the type of signalling system influences the line capacity are identified. The benefits of continuous signalling systems in comparison to traditional fixed block signalling systems are quantified. The basic requirements of a simulation tool suitable for studying realistic scenarios and capacity-related problems on a railway main line are discussed.