Improving railway maintenance schedules by considering hindrance and capacity constraints

The availability of railway networks is important for society and the economy. To keep the infrastructure in good condition, regular maintenance is needed. Regular maintenance is achieved by devising maintenance schedules that assign safe work zones to crews executing preventive maintenance activities. This study aims to optimize the maintenance schedules for both train operators and maintenance contractors, by considering (a) hindrance for parked passenger trains and planned freight trains, and (b) the workload for track workers. Further, maintenance operations are distinguished into different engineering fields (switches, straight tracks, and overhead wiring) since this influences the amount of hindrance. The method presented for designing maintenance schedules is a novel mixed-integer linear programming (MILP) model that considers these aspects. In our Dutch case study, we assess our new scheduling model and show that large improvements can be made in terms of mean workload for work crews and total hindrance for train operators. We also assess the computational costs when using exact (branch-and-bound) or metaheuristic solution methods for solving networks with up to 25 work zones.