Variations in Motorists' Valuations of Travel Time with Traffic Conditions

The value of travel time savings in part depends upon the disutility of the travel time that is saved and partly on the use to which the time saved is put. It has long been recognized that the disutility of the time spent traveling also depend upon a wide range of factors such as the journey length or the effort, comfort and safety associated with traveling. Hence one might expect the value of motorists' travel time to vary with the traffic conditions as represented by the degree of congestion, in part to reflect the more difficult driving environment when there are more vehicles, but also a higher sense of frustration, similar to that associated with waiting time and contributing to its premium valuation. In this context, and despite the predominance of car travel in developed countries, the empirical evidence specifically relating to car values of travel time tends generally to fail to distinguish between different types of time according to the degree of congestion. Thus the authors are commonly left unclear as to precisely what type of time has been valued. Moreover, when this distinction is made, it tends to be into a simple dichotomy of congested and uncongested traffic. This paper provides new evidence on the variation in the valuation of motorists' travel time savings across a finer gradation of time types than has been hitherto attempted and by means of analyzing stated preference data collected from different tolled road contexts in the United Kingdom and the United States.