A new ILP-based refinement heuristic for Vehicle Routing Problems

In the paper we address the Distance-Constrained Capacitated Vehicle Routing Problem (DCVRP), where k minimum-cost routes through a central depot have to be constructed so as to cover all customers while satisfying, for each route, both a capacity and a total-distance-travelled limit. Our starting point is the following refinement procedure proposed in 1981 by Sarvanov and Doroshko for the pure Travelling Salesman Problem (TSP): given a starting tour, (a) remove all the nodes in even position, thus leaving an equal number of "empty holes" in the tour; (b) optimally re-assign the removed nodes to the empty holes through the efficient solution of a min-sum assignment (weighted bipartite matching) problem. We first extend the SarvanovDoroshko method to DCVRP, and then generalize it. Our generalization involves a procedure to generate a large number of new sequences through the extracted nodes, as well as a more sophisticated ILP model for the reallocation of some of these sequen...

• Type: Journal
• Year: 2006
• Where: MP
• Authors: Roberto De Franceschi, Matteo Fischetti, Paolo Toth
• Keywords: Distance-Constrained Capacitated Vehicle, Empty Holes, MP 2006, Travelling Salesman Problem