A new solution approach to the truck scheduling problem in distribution centres

A distribution centre in the logistic chain acts as an interface between suppliers and retailers. Goods entering the centre by inbound trucks are unloaded, consolidated with respect to the retailer's orders, and then loaded into the outbound trucks, ready to be distributed. We consider the problem of scheduling unloading and loading operations of full-load trucks at a cross-docking distribution centre, where goods either are directly transshipped, or eventually warehoused for a very short time . Here we model the problem as a mixed integer linear program and propose a Lagrangian Relaxation approach. We show that the relaxed problem decomposes in two combinatorial subproblems. We study the mathematical properties of the relaxed problem from which we derive an attractive Lagrangian heuristic algorithm. Finally we present and discuss some numerical results.