Comparison of Vertical Alignments for Rail Transit

Abstract

In this paper two vertical alignment profiles (labeled dipped and undipped) connecting rail transit stations with different elevations are compared. A deterministic simulation model is developed and used to analyze train motion and energy use for three different vertical alignments. To minimize the cost of rail transit operation for both directions, cruising speed is optimized as a decision variable while train operations are simulated on the proposed vertical alignments. The numerical analysis and sensitivity studies show that the developed deterministic simulation model is useful for comparing vertical alignments, and that the proposed alignment concepts can significantly reduce travel time, energy use, brake wear, operating cost, and total cost compared with the baseline alignment profile.