Schedule Optimization in Interlined Metro Systems

Abstract

Interlining is a routing practice that aims to reduce the amount of transfers necessary to make journeys within a metro system through the use of routes that traverse multiple core sections called trunks. However, this practice also introduces merge points that make scheduling interlined systems more complex, and may reduce capacity and train arrival frequencies. We develop a graph model, graphical user interface, network simulator, and scheduling algorithm to analyze and quantify the impacts of interlining. We evaluate the effects of removing interlining on perceived and actual ride times within the New York City subway system, which heavily utilizes interlining. We find that even when penalizing transfers, our proposed scheduling algorithm generates higher-quality timetables for deinterlined metro systems as compared to interlined ones.