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 operated as a hub-and-spoke system with two hubs. 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, makeup, scheduling, and locomotive assignment are all addressed. At the same time we respect hard constraints like tight service time windows and train capacities, and we avoid hub overloading. We describe our approaches for obtaining provably good quality solutions. Our algorithmic techniques involve branch-and-cut, branch-and-price, and problem-specific exact and heuristic acceleration methods. We conclude our study with computational results on realistic data.