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

Abstract

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.

A multiperiod drayage problem with customer-dependent service periods

“…Although drayage operations represent a small fraction of the total distance of an intermodal shipment, they account for a substantial share of the overall shipping costs. As a result they have been subject to a significant amount of research [1]. Yet, of that little has focused on improving their efficiency over different time periods.…”

“…According to the current carrier policy, all importers are served before all exports in any route. Although it may possible for two-container trucks to service an importer after an exporter, these routes are quite unlikely to be part of the optimal solution and result in negligible savings, if any [1].…”

A Price-and-Branch algorithm for a drayage problem with heterogeneous trucks

“…These papers proposed node-arc formulations, which have very poor linear relaxations. A set-covering formulation for this problem was proposed by (1), where all feasible routes were enumerated and an off-theshelf optimization solver was run to optimally solve realistic-sized instances. However, it runs out-of-memory in the case of large-scale problems.…”

“…Then, from the set of columns generated so far, an integer solution is sought by Cplex. The computational results are compared to those in (1). The paper is organized as follows.…”

“…Comparison on realistic-sized instances between the Price-and-Branch algorithm and the set-covering formulation enumerating all feasible routes(1) …”