Network Models for Fleet Management*

This paper presents network models to determine the optimal replacement policy for a fleet of vehicles over a finite planning horizon. First, a minimum cost‐flow model is developed to determine the optimal replacement schedule for a fleet of fixed size consisting of a single type of vehicle of various ages. The model is then extended to allow for restrictions on capital expenditures that limit the purchase of new vehicles in any time period and to allow for fluctuations in the fleet size due to planned expansion or retrenchment. Finally, a multi‐commodity network model is developed for a fleet consisting of multiple vehicle types and ages.