Empty Wagon Repositioning

This thesis considers an empty wagon repositioning problem with a perfect hub-and-spoke network. Within this problem, empty wagons are repositioned while the overall costs are minimized. Based on supply and demand, the wagons are repositioned under the assumption that they depart somewhere during the day and arrive before the end of the day. Small problems are solved with an integer programming (IP) problem which is based on a multi-commodity flow formulation. However, the introduced IP formulation is new, as it also takes reclassification costs explicitly into account. Wagons that travel a part of their route together, can be seen as one block during that part. This lowers the reclassification costs on that part of the route. For larger problems three heuristics are proposed, which are all based on the principle of splitting the complete problem into smaller sub problems which are then solved with the IP. Computational tests indicate that two heuristics can be used for practical purposes.