Application of Variable Tolls on Congested Toll Road

Abstract

This paper examines how different price elasticities of travel demand would impact traffic on a toll road with a time-of-day variable toll rate. Price elasticities were derived from data collected on a pair of bridges that currently offer tolls that vary by time of day. Both aggregate traffic data and disaggregate driver data were used to determine a range of probable elasticities. The aggregate method applied the short run price elasticities observed at the operational bridges to a hypothetical toll road. To determine disaggregate elasticity rates, discrete choice models of a driver’s willingness to alter his or her time of travel due to the variable toll were estimated using survey data. Using these models, and varying the socioeconomic and commute characteristics of drivers on the hypothetical toll road, it was possible to determine the impact of different price elasticities on the flow of traffic. Elasticities from −0.076 to −0.15 caused travel times to improve by 8.8 to 13.3%, respectively.