Optimization of special vehicle routing problem based on ant colony system

In emergent airdropping, there are some special requirements for the vehicle routing problem. The airdropping personnel and equipment, geographically scattered, should be delivered simultaneously to an assigned place by a fleet of vehicles as soon as possible. In this case the objective is not to minimize the total distance traveled or the number of vehicles as usual, but to minimize the time of all personnel and equipment delivered with a given vehicle number. Ant colony system with maximum-minimum limit is adopted to solve these problems. The distance of each route is computed and the route with maximum distance is chosen. The objective is to minimize the maximum distance. The algorithm is implemented and tested on some instances. The results demonstrate the effectiveness of the method.