An integrated model for high-speed rolling-stock planning and maintenance scheduling

High-speed trains have to undergo special maintenance services. The maintenance service is highly specialized and can only run on specific platforms. Most of the optimization models proposed in the literature do not consider this problem integrated with the rolling-stock planning, although the two problems affect each other, and their separation leads to suboptimal solutions of the overall problem. This article presents an integrated approach based on a mixed integer mathematical formulation and computational results on a testbed of instances, derived from a real-world case study. This approach is compared with a two-stage one, commonly used in practice and in the literature. The results show that the rolling-stock planning problem can produce input parameters for the scheduling problem for which no feasible schedules exist. When a scheduling solution exists, the final percentage gap of the two-stage solution is much higher than the one provided by the integrated model.