Value of Highway Information Systems

Abstract

After the generalized deployment of advanced traveler information systems, there exists an increasing concern about their profitability. The costs of such systems are clear, but the quantification of the benefits still generates debate. This chapter analyzes the value of highway travel time information systems. This is achieved by using notions of expected utility theory to develop a departure time selection and route choice model. The model assumes that every driver has a level of accepted lateness for his trip and some perceived knowledge of the travel times on the route. Only these two inputs support his decisions. The decision making process does not require the consideration of a complex cost function and does not involve any optimization. The results of the model are used to compute the unreliability costs of the trip (i.e. scheduling costs and stress) and to obtain the benefits of real-time information systems. Results show that travel time information only has a significant value when there is an important scheduled activity at the destination (e.g. morning commute trips), in case of total uncertainty about the conditions of the trip (e.g. sporadic trips), or when more than one route is possible. Systems with very high accuracy do not produce better results. The chapter also highlights the difference between the actual value that information provides to the drivers and the value they perceive, which is much smaller. For instance, massive dissemination of travel time information contributes to the reduction of day-to-day travel time variance. This favors all drivers, even those without information, although they do not realize it. This misperception suggests limited willingness to pay for travel time information.