Modelling and Solving a Train Path Assignment Model with Traffic Day Restriction

The German Railway Company (DB Netz) schedules freight trains by connecting pre-constructed slots to a full train path. We consider this problem with special attention to traffic day restrictions and model it by a binary linear decision model. For each train request a train path has to be constructed from a set of pre-defined path parts within a time-space network. Those train requests should be realized only at certain days of the week. Each customer request has a specific traffic day pattern, which is a difficult challenge for the allocation process. Infrastructure capacity managers intend to achieve an efficient utilization of the capacity, whereas customers are interested in homogeneous train paths, i.e. they want the same traffic path connection for all requested traffic days. We discuss those partly contradictory requirements within the context of our binary linear decision model. The problem is solved by using column generation within a branch and price approach. We give some modeling and implementation details and present computational results from real world instances.