Fuzzy optimization model based tolerance approach to timetable rescheduling for high speed railway in China

A fuzzy optimization model based tolerance approach is proposed to handle timetable rescheduling in high speed railway during speed restriction period. As the limited speed and headway time are not crisp figures in practice especially when some natural hazards happen or some equipment failure, tolerance approach is introduced with the fuzzy membership functions of the original objective and soft constraints to find an new optimal objective with little slack of constraints. The original objective is treated in the same manner as the soft constraints, so the model is symmetric. The proposed fuzzy rescheduling model is simulated on the busiest part of a high speed railway line in China. The entire case study shows the significance of fuzzy optimization in case of speed restriction. The results shed light on how we could choose a better limited speed and headway time, so that the number of seriously impacted trains can be reduce greatly with little cost and risk.