AN EXACT MODEL FOR A VEHICLE ROUTING PROBLEM WITH LOCKERS

The Vehicle Routing Problems with Lockers (VRPL) involve strategically located storage structures to receive demands from different customers. Customers assigned to lockers must travel to the designated location, incurring an assignment cost. The objective is to define routes and assignments so that every customer is either directly served or assigned to a visited locker, aiming to minimize the total traversal and assignment costs. This study examines a variant that includes time windows, vehicle and locker capacities, and the limitation of a single visit to each locker. To solve the problem exactly, a Branch-and-Cut-and-Price algorithm is proposed using the VRPSolver framework. Computational experiments demonstrate the robustness of the procedure, which outperforms the best exact method in the literature and achieves the optimal solution for several instances with up to 60 customers for the first time.