Enhanced Branch-Cut-and-Price Algorithm for Heterogeneous Fleet Vehicle Routing Problems
Résumé
This paper considers a family of Vehicle Routing Problem (VRP) variants that generalize the classical Capacitated VRP by taking into account the possibility that vehicles di↵er by capacity, costs, depot allocation, or even by the subset of customers that they can visit. This work proposes a branch- cut-and-price algorithm that adapts advanced features found in the best performing exact algorithms for homogeneous fleet VRPs. The original con- tributions include: (i) the use of Extended Capacity Cuts, defined over a pseudo-polynomially large extended formulation, together with Rank-1 Cuts, defined over the Set Partitioning Formulation; (ii) the concept of vehicle-type dependent memory for Rank-1 Cuts; and (iii) a new family of lifted Extended Capacity Cuts that takes advantage of the vehicle-type dependent route enumeration. The algorithm was extensively tested in in- stances of the literature and was shown to be significantly better than pre- vious exact algorithms, finding optimal solutions for many instances with up to 200 customers and also for some larger instances. A new set of set of benchmark instances is also proposed.