The Idaho Department of Transportation (!DT) is interested in the development of a computer model that can calculate an estimate of user costs of travel time delays due to work zones. The IDT hopes that such a computer model could generate a benefit/cost ratio that wilt aid in the decision making process regarding future highway construction projects. The project is similar to a computer program previously developed for the IDT by the University of ldaho (U of I) that calculated the economic impact oftime delays induced by winter road conditions. The U of I has been conducting some research into various methods of calculating the costs associated with travel time delays and the idea of adapting the existing computer model. The preliminary results are encouraging and point towards the development of a working model. However, the model used by the U of I to predict user delays due to winter conditions and the type of maintenance used is much less compHcatedthen the prevailing models for work zones delays. This paper will discuss the methods that have been used by researchers to:
(1) Calculate the time delay to road users induced by a given construction or road maintenance project
(2) Translate that time delay into a dollar amount (user costs).
The conversion into a dollar amount represents the amount of money that the State of Idaho’s public will lose as a result of any vehicle time delay. In order for the U of I to derive the necessary background infonnation needed for these calculations, an extensjve literature review was conducted.