Saving based algorithm for multi-depot version of vehicle routing problem with simultaneous pickup and delivery

The paper presents saving based algorithm for the multi-depot version of VRPSPD. We developed four saving based algorithms for the problem. These algorithms are: 1) partition based algorithm; 2) nearest depot algorithm; 3) saving algorithm; 4) Tillman's saving algorithm. In the saving heuristics, a new route is created by merging two routes. Checking the feasibility of new route obtained after merging two routes is difficult because of the fluctuating load on the route. We use cumulative-net pick approach for checking the feasibility when two existing routes are merged. Numerical experiment is performed on benchmark problem instances available in literature. The numerical results show that the performance of the proposed heuristics is qualitatively better than the existing insertion based heuristics.