Optimal Location of Submain Tracks on an Urban Railway Line

AbstractDetermining the location of submain tracks (SMTs) or sidings to accommodate flexible operation is a critical issue in supporting construction investments and meeting passenger preferences. This project considered the problem of calculating the optimal location of SMTs. The objective was to minimize the sum of the construction costs for the SMTs and the total delay cost for passengers. We introduced properties for two train types. Additionally, we developed a mixed-integer model for multiple train types. We propose a procedure for using our model to determine the locations of SMTs for various headways and traffic mixes, and conducted numerical experiments to verify its performance. The results confirmed that our procedure is practical for an urban railway because the average total delay does not increase by more than about 55% compared with the optimal solution for any operational scheme.