The Short-Run Impact of Gas Prices on Toll Road Use

One of the primary functions of transportation planning is to predict future travel behavior. Using estimated travel patterns, planners can then help decision makers select the array of projects that will best suit the needs of their community. Travel behavior is a function of many variables, with cost being among the most important. Recent fluctuations in the price of gas provide an excellent opportunity to observe the impact of the price of gas on travel behavior. This project goes a step beyond looking at the elasticity of travel with respect to gas price by examining how recent changes in gas prices have impacted travel on specific facilities: toll facilities. Data from around the US was used to examine how traffic levels on toll roads have been affected by fluctuations in gas prices over the last several years. This study developed models that account for the many other exogenous factors influencing toll road use (such as local economy, population, and toll rates), and provide an elasticity of toll road demand with respect to gas price independent of those other factors. This study will provide planners and toll road authorities with valuable information on how travelers react to increasing cost of travel when already selecting a mode with an added cost (the toll). The research findings indicated that travel demand elasticity estimates with respect to gas price were inelastic and mostly negative. Elasticities found here for the period from 2000 to 2010 ranged from -0.36 to +0.14, similar to those found in the literature for non-toll facilities. However, the average value of the elasticities found here were much smaller (closer to -0.06) than those found for non-toll facilities.