An improved ant colony optimization for green multi-depot vehicle routing problem with time windows

We investigate in this paper a new variant of multi-depot vehicle routing problem with time windows is studied (GMDVRPTW), an extension of the MDVRPTW. In the new variant, the proposed GMDVRPTW consists of determining the vehicle's speed in order to minimize a function comprising fuel consumption and resulting emission costs. An integer programming model is formulated with two objectives to find the minimum travel cost and total fuel consumption and CO2 emissions under the constrains of time window, capacity of the vehicle, the fleet size. As the problem is an NP-Hard problem, we develop an improved meta-heuristic, based on an ant colony optimization and local search to solve the problem. The results show that the proposed approach is competitive in terms of solution quality.