A path relinking algorithm for a multi-depot periodic vehicle routing problem

In this paper, we consider a multi-depot periodic vehicle routing problem which is characterized by the presence of a homogeneous fleet of vehicles, multiple depots, multiple periods, and two types of constraints that are often found in reality, i.e., vehicle capacity and route duration constraints. The objective is to minimize total travel costs. To tackle the problem, we propose an efficient Path Relinking Algorithm whose exploration and exploitation strategies enable the algorithm to address the problem in two different settings: 1) As a stand-alone algorithm, and 2) As a part of a cooperative search algorithm called Integrative Cooperative Search (ICS). The performance of the proposed Path Relinking Algorithm is evaluated, in each of the above ways, based on standard benchmark instances. The computational results show that the developed PRA performs well, in both solution quality and computational efficiency.