Dynamic Value Pricing as Instrument for Better Utilization of High-Occupancy Toll Lanes: San Diego I-15 Case

Abstract

Selected results are presented of the Traffic Study, one of 12 studies conducted by San Diego State University for the I-15 Congestion (Value) Pricing Project in San Diego, California, a 3-year federal demonstration that converted underutilized high-occupancy-vehicle (HOV) lanes into a high-occupancy toll (HOT) facility. The studies addressed traffic and traveler-related aspects, as well as economic, equity, and public relations issues. The Traffic Study constituted the core of the evaluation effort. One of the project's main objectives was better utilization of the express lanes to carry more traffic during peak commuting periods. This study examines the possibility that dynamic, traffic-sensitive value pricing, represented by the FasTrak phase of the project, is uniquely suited to improve both utilization and volume distribution during peak periods while effectively controlling level of service on the facility. Measures of utilization and volume distribution were defined and studied in spring and fall waves of the study. The study confirms statistically significant improvements in both peak-period utilization and volume distribution across the study waves. The results strongly suggest that the FasTrak program's dynamic fee structure was able to create desirable redistribution of a portion of express lane traffic from the middle of the peak to the shoulders. The fixed-fee structure of ExpressPass, the preceding program, was not able to create such redistribution. Despite the steady increase of express lane volume during the entire 3-year demonstration, the comfortable level of service C required by law was maintained at virtually all times.