Delivery routing problem with multiple vehicles and multiple depots

This paper deals with multiple routing problem, which is one kind of combinatorial optimization problems. Given a certain number of deliverers make routes so as to pass the specified transit points. This problem is to find a routing plan which have the shortest total routing length. The routing plan is to determine a set of transit points and its transit order for each deliverer. From this,plan, all transit points are devided into some clusters as the deliverer's territory. The basic idea of proposed procedure is that the initial clusters are not determined strictly, but defined roughly. Final routing plan is formed step by step in consideration of the balance of length of all local routes. This paper uses the fuzzy c-means method for rough clustering. Outstanding point of the proposed method is to be able to cope with multiple depots. Comparisons with conventional methods are presented.