Attitudinal, behavioral, and institutional findings are summarized from the evaluation of the Interstate 15 (I-15) congestion pricing project, a 3-year demonstration that allowed single-occupant vehicles to use the existing I-15 high-occupancy-vehicle lanes, known as the I-15 express lanes, for a fee. The project was part of the FHWA Congestion Pricing Pilot Program and was managed by the San Diego Association of Governments. San Diego State University conducted an independent, multielement evaluation of the project. FasTrak offered all travelers on I-15 a choice of whether to pay for the use of the lanes. FasTrak users saved time by using the express lanes. The most-cited reason to join FasTrak was the need for on-time arrival. FasTrak users and I-15 carpoolers continuously perceived traffic conditions in the I-15 express lanes as satisfactory. A majority of FasTrak customers and an increasing fraction of I-15 carpoolers considered the project successful. Equity issues did not emerge despite the fact that FasTrak users came from the highestincome groups. Potential business interest in a program like FasTrak primarily hinges on the company’s perceived dependency on a corridor in which the program is installed. Homeowners surveyed considered the I-15 pricing program as a secondary factor in their decision to relocate along the I-15 corridor. Many involved in implementing the project perceived that the project matched or exceeded their expectations. They stated that it proved that pricing was a technically and politically viable strategy. The media satisfactorily informed the public about the project.

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Traffic-related findings from the evaluation of the Interstate 15 (I-15) congestion pricing project are summarized. The project was a 3-year demonstration that allowed single-occupant vehicles (SOVs) to use the existing I-15 high-occupancy-vehicle (HOV) lanes, known as the I-15 express lanes, for a fee. San Diego State University conducted an independent, multielement evaluation of the I-15 pricing project to assess its impacts for both the ExpressPass and FasTrak phases of this demonstration. The primary project goals were ( a) to maximize use of the existing I-15 express lanes, ( b) to test whether allowing solo drivers to use the express lanes’ excess capacity could help relieve congestion on the I-15 main lanes, ( c) to fund new transit and HOV improvements in the I-15 corridor, and ( d) to use a market-based approach to set tolls. At the end of 1999, the I-15 pricing project was meeting its primary objectives. There was substantially better utilization of the express lanes. Both ExpressPass and FasTrak were feasible solutions for generating sufficient revenue to fund the new express bus service, called Inland Breeze. Neither ExpressPass nor FasTrak negatively affected carpool volumes on the express lanes; FasTrak was able to redistribute volumes from the middle of the peak to the peak shoulders. Free-flow conditions were maintained at virtually all times. The project’s primary benefit was the reliability of ontime arrival for users. The project was also able to slightly alleviate congestion on the I-15 main lanes. SOV violation rates in the I-15 express lanes remained substantially below the preproject level. Also discussed are the air quality, delay, and park-and-ride impacts of the project.

In spite of the recent progress made in household activity analysis and travel budget studies, urban transportation modeling still remains a "not,too-well developed" research field. There are conflicting theories, analysis units are not uniform, terms are not precisely defined, basic studies of sub-systems involved are not yet completed, and many models lack behavioral background as well as basic attributes such as simplicity, sensitivity, compatibility, transferability and forecasting ability.Gaps in methodology may be partially responsible for this situation. There is an urgent need for simple, yet not primitive, easily applicable urban transportation models which can respond to the technical needs of planners and engineers. Lessons from the past, as well as experiences from other disciplines, suggest that future research should concentrate on: (1) new, "unconventional" approaches based on systematic, basic studies of all sub-systems involved; (2) proper definition and stratification of an analysis unit; (3) revision and unification of definitions, classifications, etc., in order to improve the behavioral background of the models; (4) dynamic rather than static approaches, able to describe feedbacks between transportation and land-use as well as between transportation demand and supply; (5) interrelations between subsequent sub-models, particularly between car availability, trip generation and modal split; (6) developing models which are not only sensitive to transportation policies but also to other local policies (e.g. land use, city development, social, etc.).

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.