In an ideal world, all railway tracks would be available to trains at all times. In reality, track sections need to be closed every now and again for track maintenance and upgrades in order to ensure a satisfactory level of safety and comfort. In this paper, we present a MIP model that optimizes a production plan with regard to both trains and preventive maintenance. The planned maintenance activities may not be canceled, but may be moved in time within pre-defined time windows. Trains may be moved in time, redirected to other parts of the geography, or even canceled. The goal for the optimization is to find the best possible traffic flow given a fixed set of planned maintenance activities. In addition to presenting the model, we discuss the current maintenance planning process in Sweden, and exemplify the usefulness of our model in practice by applying it to two typical scenarios.
Funding text 1: The project has been funded by Trafikverket (the Swedish Transport Administration) , Grant TRV 2010/25229 . We would like to take the opportunity to thank Hans Dahlberg, Per Edholm and Jakob Fritzell at Trafikverket for contributing with their expert knowledge, and the anonymous reviewers for their valuable comments that helped to improve this paper.