Driven by new laws and regulations concerning the emission of greenhouse gases, carriers are starting to use battery electric vehicles (BEVs) for last-mile deliveries. The limited battery capacities of BEVs necessitate visits to recharging stations during delivery tours of industry-typical length, which have to be considered in the route planning in order to avoid inefficient vehicle routes with long detours. We introduce the Electric Vehicle Routing Problem with Time Windows and Recharging Stations (E-VRPTW), which incorporates the possibility of recharging at any of the available stations using an appropriate recharging scheme. Furthermore, we consider limited vehicle freight capacities as well as customer time windows, which are the most important constraints in real-world logistics applications. As solution method, we present a hybrid heuristic, that combines a Variable Neighborhood Search algorithm with a Tabu Search heuristic. Tests performed on newly designed instances for the E-VRPTW as well as on benchmark instances of related problems demonstrate the high performance of the heuristic proposed as well as the positive effect of the hybridization.

In this paper, we investigate a routing problem arising in the last-mile delivery of small packages. The problem, called Multi-Depot Vehicle Routing Problem with Private fleet and Common carriers (MDVRPPC), is an extension of the Multi-Depot Vehicle Routing Problem (MDVRP) where customers can either be served by the private fleet based at self-owned depots or by common carriers, i.e., subcontractors. We develop an effective Variable Neighborhood Search algorithm based on the use of cyclic-exchange neighborhoods that incorporates an adaptive mechanism to bias the random shaking step. The approach is successfully used to solve MDVRPPC as well as closely related problems, such as the MDVRP and the single-depot VRP with Private fleet and Common carriers (VRPPC), obtaining high quality solutions within short computing time. Our extensive testing on these problems shows the positive impact of the adaptive mechanism with respect to a standard VNS algorithm.

No abstract

Territory-based routing approaches (TBRAs) are commonly used to achieve high service consistency, e.g., in the small package shipping industry, but their drawback is a decline in routing flexibility. Consequently, a high percentage of time-definite deliveries, as common in the small package shipping sector, should have a significant negative effect on the solution quality of TBRAs. To the best of our knowledge, no study exists on the magnitude of this effect and the factors that influence it. Therefore, we develop a two-phase TBRA and use it i) to investigate the design requirements of a TBRA for successfully handling time windows, and ii) to study the influence of time window constraints on the performance of such an approach. We find that the consideration of geographical aspects in the districting is paramount for generating high-quality territories, while explicitly incorporating time window characteristics and historical demand data does not lead to a perceptible improvement of the solution quality. Moreover, the efficiency and feasibility forfeits of our TBRA in comparison to daily route reoptimization (RR) are larger if time windows are present. However, significantly higher consistency improvements compared to RR are achieved for time-constrained problems. This is due to the fact that RR solutions to time-definite problems exhibit lower consistency and thus a higher potential for improvement by using a TBRA, which constitutes an important insight for practitioners.

No abstract