Abstract
In this paper, a data model is proposed which takes the form of a string which represents the vehicle routing problems (VRP) with various conditions including time windows, the pickup and delivery, the repeated delivery and the multiple depots. The simulated annealing is adopted as an optimization technique to solve VRP. The objective of the proposed model is to minimize the total cost that consists of the vehicle operation cost, the depot operation cost and the working cost of drivers. The scheme deals with the VRP with complicated constraints by an extremely simple procedure compared to other methods, but also generates good quality solutions. (A*)