Optimizing the Cargo Express Service of Swiss Federal Railways

The Cargo Express service of Swiss Federal Railways (SBB Cargo) offers fast overnight transportation of goods between selected train stations in Switzerland and is currently operated as a two-hub and spoke system. We present three different models for planning the operation of this service as a whole. All models capture the underlying optimization problem with a high level of detail: Traffic routing, train routing, make-up, scheduling, and locomotive assignment are all addressed. At the same time we respect hard constraints like tight service time windows, and train and yard capacities. To the best of our knowledge, such an integration of planning steps into one exact approach has not been successfully attempted before. We describe our approaches for obtaining provably good quality solutions. Our algorithmic techniques involve branch-and-cut, branch-and-price as well as problem specific exact and heuristic acceleration methods. We conclude our study with computational results on realistic data.