The vehicle flow formulation and savings-based algorithm for the rollon-rolloff vehicle routing problem

The rollon-rolloff vehicle routing problem (RRVRP) has drawn much attention of researchers due to the increasing concerns on waste material logistics. In literatures the RRVRP is formulated as the node routing problem with asymmetric arc cost and a maximum route length. In this paper we adopt the trip decomposition method to transfer the trip to arc demand so as to propose a vehicle flow formulation for the RRVRP. A two-stage heuristic involving the modified Clarke and Wright savings heuristic algorithm (CW) followed by a local search phase is developed to solve the formulation. The effectiveness of the proposed formulation and heuristic is demonstrated by computational experiments on randomly-generated small-scale instances and benchmark instances.