The growing interest in recent years in the use of operational research methods in fleet management probably stems from the realization that the cost of distribution of goods and services constitutes in some cases a significant proportion of the sales value of items. It is not surprising, therefore, to find many studies concerned with the problems of fleet management: What size should the fleet be? What replacement policy for the purchase of new vehicles should be adopted? What maintenance policy is best? How should the fleet be used to deliver goods in response to customer demand?