the multi-depot vehicle routing problem of heterogeneous fleet of vehicles with time windows for perishable commodities

this paper discusses the multi-depot vehicle routing problem of heterogeneous fleet of vehicles with time windows for perishable commodities. the objective of the problem is to minimize the total time required for servicing all customers that is equivalent to the total cost. commodities are delivered to the customers with defined time windows by a fleet of heterogeneous vehicles, which have limited capacities. the mentioned problem is a more general version of vehicle routing problem (vrp), hence it belongs to np-complete complexity class and we present a max-min ant colony algorithm to solve the model approximately in practical dimensions. finally, the experimental results have shown that the presented algorithm has appropriate performance in comparison with well-known instances in a reasonable time.