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Open Access Publications from the University of California

San Diego's I-15 Congestion Pricing Project: Preliminary Findings


This paper presents the preliminary findings from the Phase I evaluation of the Interstate 15 (I-15) Congestion Pricing Project in San Diego. It is a three-year demonstration that allows single occupant vehicles (SOVs) to use the existing 1-15 high occupancy vehicle (HOV) lanes for a fee. In Phase I, program participants were charged a monthly fee for unlimited use of the I-15 HOV lanes. The primary objectives of the project are: (1) to maximize use of the HOV lanes; (2) to test whether allowing solo drivers to use the HOV lanes' excess capacity can help relieve congestion on the main lanes; (3) to improve air quality; and (4) to fund new transit and HOV improvements in the I-15 corridor. 

San Diego State University (SDSU) is conducting an independent, multi-element evaluation of the project to assess its impacts. The study will consider the project's progress in meeting its primary objectives and provide detailed insight into the affect of congestion pricing on the I-15 corridor. The project has the potential to contribute to the broader understanding of many practical aspects associated with the implementation of congestion pricing in metropolitan areas. It also supplies data for the evaluation of benefits, which is central to the discussion of equity in the context of congestion pricing. 

This paper provides an overview of the project status and preliminary findings presented in detail in 22 Phase I technical reports that address a range of topics such as traffic, travel behavior, and institutional issues. 

The results from the first year of operations are limited, but indicate the project's relative success. The project appears to be meeting its main objectives. In particular, the total number of vehicles using the HOV lanes increased substantially. The increase is attributed to increased number of carpools as well as project participants. The level of service (LOS) in the HOV lanes has not been adversely affected; LOS C was maintained throughout Phase I. In addition, there was a slight reduction of overall traffic volumes on the main lanes. 

Public acceptance of the project was evident in Phase I. The program participants viewed it as a success. However, understanding of the project's overall objectives was low among both the program participants and the public. The majority of 1-15 users thought the ExpressPass program was fair to I-15 main lane and HOV lane users. Finally, there was evidence of sensitivity to price increases, although price levels during Phase I were not high enough to deter demand for the program. 

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