High occupancy vehicle (HOV) lanes, also known as carpool lanes and diamond lanes, are designated for use by carpoolers, transit riders, ridesharers, and motorcycles that meet the occupancy requirement. By restricting access, the HOV lanes benefit users by allowing them to travel the freeway system at a faster speed, thus saving time and experiencing greater travel time reliability in comparison to motorists on general purpose (GP) lanes. To accurately evaluate the system's effectiveness, a state policy requires an annual HOV system report to document system performance, examining the HOV lanes' person-carrying capability, travel time savings, and trip reliability benefits in comparison to adjacent GP lanes, as well as the lanes' violation rates.
This report describes the results of an extensive monitoring effort of HOV lane use and performance in the Puget Sound area in 1998. It presents an analysis of data collected to describe the number of people and vehicles that use those lanes, the reliability of the HOV lanes, travel time savings in comparison to GP lanes, violation rates, and public perceptions. This information is intended to serve as reliable input for transportation decision makers and planners in evaluating the impact and adequacy of the existing HOV lane system in the Puget Sound area and in planning for other HOV facilities.
Descriptions of the tool set and methodology for analyzing HOV facility usage and performance in terms of vehicle and person throughput, travel time, and speed and reliability measures are provided in a separate report titled Evaluation Tools for HOV Lanes Performance Monitoring.