Shunting scheduling method in a railway depot for dealing with changes in operational conditions

A shunting schedule in a railroad depot consists of instructions to allocate or move train-units in the field. In this paper, we propose a scheduling method which can reconstruct solution in response to various changes in operational conditions. Under classification of train-units to be re-scheduled into two sets; one is a group of having invalid schedule (ISU) and another is a group of having valid schedule (VSU), the method is escalating the re-scheduling target by adding ISUs to a set of VSU and repeatedly solving a partial problem of the target until all the unit is processed. Based on the mathematical model which formalizes the problem as a kind of Flexible Job Shop Scheduling Problems (FJSSP), the partial solution can be derived by an algorithm which uses Constraint Programming (CP) with domain-oriented heuristics. Being evaluated on some test cases, it is showed that the proposed method can find a reasonable solution in a practical time while suppressing the differences from the original schedule.