The Vehicle Routing Problem (VRP) is an important management problem in the field of physical distribution and logistics. In practice, the logistics system usually includes more than one depot, and the start of the service at each customer must be within a given time window. Hence, the Multi-Depot Vehicle Routing Problem with Time Windows (MDVRPTW) is an important variant of VRP. The MDVRPTW is a very difficult combinational optimization problem, due to many complex constraints are involved. This research aims to propose a Multiple Ant Colony System (MACS) to solve the problem. Moreover, two hybrid algorithms, which combine the strengths of the MACS and the Simulated Annealing (SA), are developed to improve the solution quality. The performance of the proposed algorithms are tested on several benchmark instances and compared with other algorithms in the literature. The computational results show that our proposed algorithms are effective to solve the MDVRPTW and 6 new best solutions are found.
Samenvatting