A decision support system for a real vehicle routing problem

The vehicle routing problem has been widely studied in the literature, mainly because of the real world logistics and transportation problems related to it. In the present paper, a new two-stage exact approach for solving a real problem is shown, along with decision making software. In the first stage, all the feasible routes are generated by means of an implicit enumeration algorithm; afterwards, an integer programming model is designed to select in the second stage the optimum routes from the set of feasible routes. The integer model uses a number of 0-1 variables ranging from 2000 to 15,000 and gives optimum solutions in an average time of 60 seconds (for instances up to 60 clients). An interactive decision support system was also developed. The system was tested with a set of real instances and, in a worst-case scenario (up to 60 clients), the routes obtained ranged from a 7% to 12% reduction in the distance travelled and from a 9% to 11% reduction in operational costs. (C) 2003 Elsevier B.V. All rights reserved.