A Two-Phase Approach to Routing a Mixed Fleet with Intermediate Depots

The adoption of all-electric vehicles (EVs) has grown rapidly in the transportation industry, particularly for urban parcel deliveries. However, the limited driving range of EVs and the high investment cost of establishing charging infrastructures are still the holdbacks to routing these EVs. In this paper, we present the vehicle routing problem of a mixed fleet of EVs and conventional vehicles (CVs) via intermediate depots as an alternative strategy to address the challenges, with CVs delivering parcels from the central depot to intermediate depots and EVs delivering parcels from intermediate depots to customers. In addition, we propose an intelligent dispatching scheme to allow EVs to be used for multiple routes. A two-phase approach is developed to first cluster the customers to the intermediate depots and then route the mixed fleet. The strategy is implemented for both small- and large-sized instances, and the results show that using an intelligent dispatching scheme can significantly reduce the number of EVs used. Furthermore, the use of smaller-range EVs is also investigated., and a discussion of potential implementation issues is provided.