Estimating the Vehicle operating cost used for economic feasibility analysis of highway construction projects

Vehicle operating cost (VOC) is an integral part of the economic benefit estimation in the economic evaluation in feasibility studies of highway projects. It is expected that improved road conditions or reduction in congestion due to construction of a new road or upgrading of an existing road will reduce the vehicle operating cost of the affected road users. Operating cost of a vehicle type is a function of several variables including road condition, travel speed, road geometry and many other parameters. Current practice is to update VOCs in literature based on price indexes, which does not accurately represent the variation in the main factors affecting operating cost of a vehicle. Therefore, there is no reliable estimate for VOCs to be used in feasibility studies in Sri Lanka. The study evaluates VOCs of two vehicle types, namely Car and Medium truck, for varying roadway conditions to be used as representative values, for economic evaluations of highway projects in Sri Lanka, for two vehicle models. The effect of Roughness on Vehicle operating cost can be seen prominently in the obtained VOC values. It can be observed that higher speeds have a higher effect on the cost due to increasing roughness. Since HDM-4 can model continuous roughness values, combining it with a road deterioration prediction can produce accurate VOC values to be used on a cost benefit analysis of a major highway project. Further, This approach can be used to publish recommended values of VOC for various road conditions to be used in economic evaluation of feasibility studies.