a set-covering formulation for a drayage problem with single and double container loads

This paper addresses a drayage problem, which is motivated by the case study of a real carrier. its trucks carry one or two containers from a port to importers and from exporters to the port. since up to four customers can be served in each route, we propose a set-covering formulation for this problem where all possible routes are enumerated. this model can be efficiently solved to optimality by a commercial solver, significantly outperforming a previously proposed node-arc formulation. moreover, the model can be effectively used to evaluate a new distribution policy, which results in an enlarged set of feasible routes and can increase savings w.r.t. the policy currently employed by the carrier.