Mechanistic-Probabilistic Vehicle Operating Cost Model

Abstract

In the face of an aging road infrastructure and shrinking highway maintenance budgets, optimizing the allocation of limited highway resources is paramount to the Saskatchewan Department of Highways and Transportation (SHT). In order to make informed infrastructure management decisions, SHT has identified the need to accurately quantify vehicle operating costs on different roads in diverse operating conditions. SHT had previous experience with the HDM III model, but found they could not support HDM III because of the extensive data requirements. As a result, in 1991 SHT initiated a review of available road user cost models in the hope of identifying a model that would meet the specific needs of SHT. No such model was found primarily because accurately predicting vehicle operating costs on most Saskatchewan roads is difficult because of the inherent uncertainty associated with the parameters that influence vehicle operating costs. Therefore, a mechanistic-probabilistic vehicle operating cost (PVOC) model was developed to estimate vehicle operating costs of different vehicles operating on different roads in Saskatchewan conditions. The PVOC model computes a probabilistic estimate of vehicle operating costs, including the expected value and the associated uncertainty of the estimate. The PVOC model was validated for several vehicle types operating on Saskatchewan roads and was found to be within 20% of published industry averages and within 9% of historic Saskatchewan truck fleet data.