A robust enhancement to the Clarke–Wright savings algorithm

Abstract

We address the Clarke and Wright (CW) savings algorithm proposed for the Capacitated Vehicle Routing Problem. We first consider a recent enhancement that uses the put first larger items idea originally proposed for the bin packing problem and show that the conflicting idea of putting smaller items first has a comparable performance. Next, we propose a robust enhancement to the CW savings formulation. The proposed formulation is normalized to efficiently solve different problems, independent from the measurement units and parameter intervals. To test the performance of the proposed savings function, we conduct an extensive computational study on a large set of well-known instances from the literature. Our results show that the proposed savings function provides shorter distances in the majority of the instances and the average performance is significantly better than previously presented enhancements.

Keywords:

• vehicle routing
• Clarke–Wright savings algorithm
• heuristics