A Freight Service Design Problem for a Railway Corridor

We study the problem of designing a set of highly-profitable freight routes in a railway corridor, taking into account the level of service requested by different goods; in particular the profit achieved by transporting a good is a nonlinear function of the associated travel time. We propose an ILP model which is solved heuristically by column generation and fixing techniques. Computational results on a real corridor crossing eleven European countries are reported, showing that we can find solutions that are provably close to optimal. Given the large size of our instances, a key issue of our approach is to avoid finding an optimal solution of the continuous relaxation of our model, stopping as soon as near-optimal primal and dual solutions are available.