Special issue on Rich Vehicle Routing Problems

Editorial The Vehicle Routing Problem (VRP) is a key to efficient transportation management and supply-chain coordination. In broad terms, it deals with the optimal assignment of a set of transportation orders to a fleet of vehicles, and the sequencing of stops for each vehicle. The VRP has a large number of real-life applications and comes in many guises, depending on the type of operation, the time frame for decision making, the objective, and the types of constraint that must be adhered to. Outside of transportation logistics, the VRP has less intuitive but still important applications, e.g. in robotics and VLSI design. The VRP is a computationally hard, discrete optimization problem. It has been a main subject for thousands of researchers since it was introduced by Dantzig and Ramser in 1959. A large variety of optimization and approximation methods have been proposed and studied. Depending on variant and response requirements, exact VRP methods of today have a size limit of 50-100 orders. Hence, there has been much research on algorithms that are able to find high quality solutions in limited time. Our ability to find good solutions to practical variants of the VRP in a reasonable response time has increased tremendously since this problem was introduced. Improvements are not only due to a general increase in computing power, but also to substantial advances, both in exact methods and heuristics. VRP research is regarded as one of the great successes of Operations Research. The results have lead to a tool industry in route design and fleet management, through which research results have yielded huge economical and environmental savings. VRP research has often been criticized for being too focused on idealized models with non-realistic assumptions for practical applications. The methodological evolution has lead to a situation where the classical problems are now more or less regarded as being solved from a pragmatic point of view. As a result, the research community has turned to variants of the VRP which before were considered too difficult to handle. The variants include aspects of the VRP that are essential to the routing of vehicles in real-life. The family of those extended problems are often called Rich Vehicle Routing Problems. In addition to the internal motivation in the research community alluded to above, the growing tool industry and their end users provide external forces in the direction of richer VRP models. This is the backdrop for our …