Combined location–routing problems: A synthesis and future research directions

Over the past few decades, the concept of integrated logistics systems has emerged as a new management philosophy which aims to increase distribution efficiency. Such a concept recognizes the interdependence among the location of facilities, the allocation of suppliers and customers to the facilities, and the vehicle route structure around depots. As such, it coordinates a broader spectrum of location and routing options available to logistics managers and consequently avoids the suboptimization of distribution solutions. Reflecting the increasing importance of integrated logistics systems, an extensive body of combined location–routing literature has developed in less than 30 years. In this paper, we synthesize the past evolution of location–routing literature and then explore promising research opportunities in incorporation of more realistic aspects, algorithmic design, and model complexity.