Research on the model and algorithm of the flexible operation sequence of the first-level maintenance in the EMU depot

Abstract

Abstract Most of the first-level maintenance of Electric Multiple Unit (EMU) adopts the form of fixed sequence operation, known as “washing-maintenance”. Because of the limitation of the line capacity and the inconsistent arrival time of EMUs, a fixed sequence operation may give rise to such problems as longer waiting time, idle lines and waste of maintenance capacity. To solve these problems, a non-linear integer model with a flexible operational sequence of the first-level maintenance of the EMU depot is proposed in this paper. The proposed model aims at minimizing the latest completion time, taking into account the constraints such as the operation sequence of the same EMU, the limitation of simultaneous operation on the same line and the time requirement for EMU to enter and leave the yard. In the proposed model, genetic algorithm is employed. To a further level, in this paper, an application of the proposed model used in Taiyuan EMU depot is presented. With a comparison of two modes, namely, the fixed sequence mode and the fixed sequence plus manual washing mode, the case of the application by Taiyuan EMU depot provides the verification for the feasibility and validity of the model proposed. The result of the application suggests that the flexible operation sequence mode bring about improvement with regard to reducing waiting time, optimizing line utilization, shortening the latest completion time, and enhancing both working efficiency and ability of the first-level maintenance.