Optimization of internal transports in a Deutsche Post World Net's parcel sorting centre

Efficient distribution of goods is of essential importance in today's markets. For a logistics service provider it is of special importance in competition not only to plan its external transports but also to handle internal transports efficiently. This contribution considers the internal transports in a Deutsche Post World Net's main parcel sorting centre. Parcels are transported from end points at a conveyor of a sorting and distribution unit to loading gates where the vehicles for further transportation arrive. This internal transport is carried out with roll containers manually or via electro cars. Various special features have to be considered as there are different types of loading gates, additional requirements with respect to delivery and a balanced utilization of the sorting and distribution unit. The structure of the problem is analysed and a modified 3-dimensional assignment model is developed to represent the problem adequately. To solve the problem, the large model is decomposed heuristically and then standard mixed integer linear optimization software is applied. The obtained results permit to reduce the transportation effort by more than 40%.