The study was designed to check the validity of the vehicle operating cost relationships derived from an earlier study in Kenya and extend these relationships to include the effects of road geometry and poor bituminous surfaces. Data were collected over a two year period by means of a user survey and the effect of various road and vehicle parameters on the components of vehicle operating cost was examined. The results of the analysis are presented and are compared with the results obtained from the Kenya study to show the different effects of poor quality paved and unpaved roads on the cost of operating vehicles. The results of both studies are combined to produce a set of relationships for both paved and unpaved surfaces