Leistungskenngrößen für Gesamtfahrstraßenknoten

Basically a railway network consists of the infrastructure elements lines, station track groups and route nodes. Route nodes contain the switch zones in the front end of stations, linking the adjacent lines and the station tracks. Thereby train runs can be operated simultaneously, if they do not exclude each other. Analytical methods for capacity assessment are available for lines and station track groups, but for route nodes only some rudimental approaches exist. In this paper different methods will be deduced to compute the capacity characteristics theoretical capacity, loss probability, waiting probability, scheduled waiting time and unscheduled waiting time for a route node. The new approach uses a multiresource queue from queuing theory to model a route node. Because of the multi-channel feature of a route node two or even more train runs can be operated simultaneously. To achieve the theoretical capacity of the system, train runs have to be arranged optimally. To maximise the capacity it is necessary to bundle parallel train runs instead of operating them sequentially. In this publication a mathematical approach will be presented to calculate the theoretical capacity by means of linear optimisation. To determine the loss probability two different formulas are presented. Generally the complexity of the computation increases rapidly with the size of the route node. To cope with this problem an algorithm is described, which divides the system in several subsystems. These subsystems can be handled separately. Merging the results finally provides an exact result for the overall system. To estimate the waiting probability the loss probability is used in first instance. This is the same approximation Potthoff used to determine the loss probabilities of station track groups. In railway operation research scheduled and unscheduled waiting times are differentiated. Scheduled waiting times occur during the process of timetable construction, whenever a train run has to leave his designated slot to avoid a conflict with another train run. Unscheduled waiting times result from knock-on delays during operation. If there is a completely undisturbed operation, unscheduled waiting times will not arise. In these publication the unscheduled waiting times occurring in a route node are deduced by application of a modified loss- / waiting system. Furthermore an enhancement of the Strele formula by Schwanhäußer allows the calculation of scheduled waiting times of route nodes. Additionally this paper contains various sample calculations to illustrate the principles of the described methods