A Constraint Programming Model for the Open Vehicle Routing Problem with Heterogeneous Vehicle Fleet

Abstract

AbstractIn this study, the open vehicle routing problem with heterogeneous vehicle fleet (HFOVRP) is addressed. Unlike the standard vehicle routing problems, vehicles do not return to the depot after their customer visits in the open vehicle routing problems. In the HFOVRP, demands of customers must be served by a heterogeneous vehicle fleet, where the tour length of each vehicle is limited by a maximum allowed tour length. The aim of the studied HFOVRP is to minimize the total fixed cost of used vehicles. In this study, a constraint programming (CP) model is developed for the HFOVRP. A mixed-integer linear programming (MILP) formulation of the HFOVRP is also provided to make a comparison with the CP model. Then, the performances of the CP and MILP models are assessed on a set of small-sized instances with varying number of customers. The computational results show that the CP model is effective for providing good-quality solutions for small-sized instances of the HFOVRP in short computational times. KeywordsVehicle routingOpen vehicle routing problemHeterogeneous vehicle fleetConstraint programmingMathematical modelling