A critical analysis of the “improved Clarke and Wright savings algorithm”

Abstract

In their paper “An improved Clarke and Wright savings algorithm for the capacitated vehicle routing problem,” published in ScienceAsia (38, 3, 307–318, 2012), Pichpibul and Kawtummachai developed a simple stochastic extension of the well-known Clarke and Wright savings heuristic for the capacitated vehicle routing problem. Notwithstanding the simplicity of the heuristic, which they call the “improved Clarke and Wright savings algorithm” (ICW), the reported results are among the best heuristics ever developed for this problem. Through a careful reimplementation, we demonstrate that the results published in the paper could not have been produced by the ICW heuristic. Studying the reasons how this paper could have passed the peer review process to be published in an ISI-ranked journal, we have to conclude that the necessary conditions for a thorough examination of a typical paper in the field of optimization are generally lacking. We investigate how this can be improved and come to the conclusion that disclosing source code to reviewers should become a prerequisite for publication.