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Research Projects (2004-05)

Identifying Number


Project Title

High Occupancy Vehicle Lanes Evaluation III


University of Utah

Project Investigator

Dr. Peter T. Martin
Dept of Civil and Environmental Engineering
University of Utah

External Project Contact

Stan Burns
Utah Department of Transportation

Project Objective

After the urban section of I-15 had been reconstructed plans were made to extend this reconstruction beyond Salt Lake County. Currently, the freeway reconstruction in Utah County adds two lanes to the existing freeway capacity. One lane will be used by general purpose vehicles while the other will be reserved for HOV vehicles. The goal of HOV Lanes Evaluation III is to evaluate the effectiveness of the newly constructed HOV lane in the Utah County. The study's research objectives are as follows: (1) determine efficiency of the HOV lanes; (2) Assess safety; (3) Identify public's perception of the HOV lanes; and (4) Recommend changes to the existing HOV operations.

Project Abstract

High Occupancy Vehicle (HOV) lanes opened on May 14, 2001 on the reconstructed Interstate 15 (I-15) in the Salt Lake Valley. The University of Utah Traffic Laboratory did two evaluation projects on HOV Lanes in Salt Lake County. The research objectives for both projects were to evaluate the impact of the HOV lanes on I-15 and alternate routes and quantify the effectiveness by comparing before/after HOV lane statistics. The first project (Final Report UTL-1001-48) evaluated initial benefits of the HOV lane right after the lane was opened in 2001. Many benefits were recorded by this project. Travel time was found to be 13 percent lower in AM peak period and 30 percent lower in PM peak period. Average Vehicle Occupancy (AVO) increased from 1.1 to 1.3. Moveover it was found that during PM peak period the speed in the HOV lanes is 63.6 mph and in the General Purpose (GP) lanes 51.5 mph. Violation rates were 5-13 percent along the corridor and 20 percent at the ramp at 400 South. The second evaluation was conducted during 2003/2004 (Final Report UTL-1003-70) to assess the changes that might have happened in terms of user acceptance, throughout, violation, and safety. The findings have shown that almost all of the NCHRP HOV standards were met with respect to vehicle volume, person throughput, and travel time. Meeting these standards means justification of the HOV deployment. Based on the accident data analysis, HOV lanes did not appear to be inherently unsafe. A public opinion survey was conducted and the results indicate that there is strong support for the HOV lanes from both users and non-users. It was concluded from this study that the HOV lanes are performing more effectively than they did during their first year of operation. The findings indicate that the HOV lanes prove their value during more congested periods. As congestion in the Salt Lake Valley increases, the benefits of the HOV lanes are also expected to increase.

Task Descriptions

  1. Meet with technical advisory committee (TAC) and define MOE's to assess efficiency, safety and public acceptance criteria
  2. Design an HOV evaluation. Specify: What type of traffic data to collect (vehicle volume, vehicle occupancy, modal split, person throughput, travel time, speed, accident rates, violation rates); Data collection procedures and technologies (manual, video, GPS, etc.); Data collection time periods (am and pm peaks, off-peak, weekend); Data collection sample sizes; Data reduction and analysis (formulas, statistical tests, etc.); Questionnaires for interviews with drivers
  3. Draft, submit, and acquire approval of a detailed evaluation design
  4. Collect data
  5. Analyze data and produce results
  6. Meet with UDOT's TAC and present findings
  7. Deliver report

Milestones, Dates

Starting Date: July 1, 2004
Ending Date: June 30, 2005

Yearly and Total Budget


Student Involvement


Relationship to Other Research Projects

Continuation of HOV II

Technology Transfer Activities

The findings will be discussed and evaluated by both the Wasatch Front Metropolitan Regional Council, but also the Moutainlands Regional Council of Governments. The Utah Department of Transportation will, as project sponsor, chair the discussions.

Potential Benefits of the Project

The project will inform decision makers of the effectiveness of HOV lanes. This in turn will lead to better policy making for future deployment of these innovative car-pool lanes.

TRB Keywords

Driver behavior, traffic control

NDSU Dept 2880P.O. Box 6050Fargo, ND 58108-6050