Ex-ante robustness measures for single track train timetables

Abstract

The goal of the paper is to propose a measurement to quantify and improve the robustness of the train timetables at the design stage. The paper presents the modeling and application of an ex-ante robustness measure for single track railways, known as the Critical Robustness Measure (CRM). Efficiency of the CRM is demonstrated by comparing the technique with the available ex-ante robustness measures, e.g., the number of trains per hour per section, the total amount of runtime margin for each individual train, sum of shortest headway reciprocals, weighted average distance, marginal runtime difference, robustness at the critical points, and margins along the longest path. Numerical experiment sare conducted on a hypothetical example and a selected single track segment of the Pakistan Railways. Computational results reveal that it is not useful to add the time margins to all activites (e.g., running times, headways) in the timetable because not all components of margins are effective for the robustness of a timetable. Furthermore, the robustness is not statically quantifiable, since it may change with time and be associated with the way of the train’s interactions.

Keywords

• critical points
• ex-ante measures
• robustness measurement
• train timetable