Offering a Mathematical Model and Heuristic Method for Solving Multi-Depot and Multi-Product Vehicle Routing Problem with Heterogeneous Vehicle

A mathematical model and heuristic method for solving multi-depot and multi-product vehicle routing problem with heterogeneous vehicle have been proposed in this paper. Customers can order several products and depots must deliver customer's orders before due date with different vehicle. Hence mathematical model of multi-depot vehicle routing problem has been developed to represent these conditions. Aim of this model is to minimize total delivery distance or time spent in servicing all customers. As this problem is very complex, we have offered a heuristic method that includes four steps. Grouping, routing and vehicle selection, scheduling and packing of products and improvement are the aforementioned steps. Efficiency of heuristic has been tested by a case study and several numerical examples. Comparing the results of heuristic and optimal solving has revealed that the deviation of heuristic results from optimal answer is lower than eight perce.