A multi-hub Express Shipment Service Network Design model with flexible hub assignment

摘要

The Express Shipment Service Network Design problem consists in designing a network of flights that, at minimum cost, enables the overnight transportation of packages in vast regions. In this paper, we study its multi-hub version and develop a model in which the allocation of packages to hubs is a decision, unlike state-of-the-art approaches that suppose a predetermined allocation. Our formulation is strengthened with three families of valid inequalities and with improved forcing constraints. Extensive numerical experiments using instances provided by FedEx Express Europe show the efficiency of our flexible hub assignment model, particularly compared to fixed hub assignment approaches.