Research on the Optimizing Model and Solving Algorithm of Assignment Plan of CRH-Emu Depot's Repair Tracks

China Railway High-speed is expanding into a large network that covers most of the middle scale cities. To manipulate the China Railway High-speed Electric Multiple Unit (CRH-Emu) train's daily inspection and repair, 45 CRH-Emu depots were established in China. Depots are equipped with several special tracks to carry out the inspection and repair. With the repair workload's rising, the number of repair-function tracks is becoming bottleneck of depots' repair capacity. In order to improve the efficiency of CRH-Emu depot's repair tracks, this paper established an integer model, with the minimal unnecessary idle time of repair tracks as the objective function, and with back-departure depot time, and the repair demand of CRH-Emu as both operational and repair constraints, the matching relationship between CRH-Emu and tracks as the track occupation constraint. To reduce the model scale, a track occupation topological graph was constructed. Based on the graph, MAX-MIN ant system was applied to obtain optimal result. By the example of solving a typical depot's tracks utilization scheme, the model and optimization method were proved to be effective. Finally, a further discussion of software for scheduling the plan was given.