Impact of Rail Terminal Design on Transit Service Reliability

Ensuring reliable rail transit services is an important task for transit agencies. The effects of various terminal configurations on reliability of services were studied. The results could also be used for short-turning infrastructure. Short turning is a widespread measure to restore service after major disturbances; in many rail networks, additional switches are constructed to enable short turning. Calculations of the average delay per vehicle, regarding three main types of terminals, show the effect of frequency and occupancy time [determined by the distance from the switches to the platform (i.e., length of the terminal), technical turning time, and scheduled layover time]. The substantial effect of arrival variability and the number of lines using the terminal are also illustrated. With stochastic variables, delays will occur, although they are not to be expected in the static case. The best performance regarding reliability is achieved when double crossovers are situated after the platforms. Single tail tracks facilitating the turning process are acceptable only if frequencies are low, although they are often used in practice as short-tuning facilities for high frequency services. Occupancy time has a large impact on expected delays. This time can be minimized by designing short distances between switches and platform and tail tracks. Capacity management is not common in transit. However, increasing frequencies and large deviations force the consideration of limited capacity when planning infrastructure. If not, delays will occur, and additional measures will be necessary to solve them, which could be more expensive in the long term