Method for establishing locomotive working diagram based on sequential connection of locomotive routing

This paper presents an optimized locomotive working diagram model based on its practical scheduling process which is to achieve minimized turn-around time as the objective whose requirements are constrained by the relationships defined by the total number of the locomotives at arrival and departure stations, the total turn-back time cost at turn-around stations as well as the locomotives can only be allowed to be allocated at the same station. By proving the sequential characteristic that the locomotive working diagram formulating problem under constant turn-back time can be always transformed into a feasible solution respecting the principle of sequential routing connection, this paper establishes the algorithms for both scenarios including paired and unpaired locomotives. This is shown by the Guangyuan-Chengdu section of Baoji-Chengdu Railway as the example solved by the proposed model and algorithms. Better application effect of the model is demonstrated in this paper through the comparison between practical locomotive working diagram with its optimized one which saved the turn-around time about 72 hours (3.8%) and reduced the number of locomotives by 3 units (3.8%) in total.