Puget Sound freeway HOV lanes have proven to be highly efficient. They move about one third of the people on the freeways in only 18 percent of the vehicles, and carry approximately 52 percent more people per lane than other freeway lanes during the main commuting hours and directions (2006 data). For this reason, WSDOT has invested heavily in the development, maintenance and expansion of HOV freeway lanes.
Despite the system’s success and high level of public support, HOV lanes have always been surrounded with a certain degree of controversy. Do HOV lanes actually encourage people to take the bus, carpool, or vanpool? How many people would switch to solo driving if the HOV lanes were removed? Why do people choose shared-ride options? Who do people carpool with and why? This study begins to answer some of these questions.
To perform the survey, approximately 30,000 questionnaires were distributed through the mail and in-person to carpoolers, bus riders, and vanpoolers during December 2005 and January 2006. (Although motorcycles and trucks are also important users of the HOV system, this study focused on the three main user groups.) Additional phone surveys of carpoolers were also performed. The study achieved an overall response rate of 19.3 percent, with a margin of error of ±1.3 percent.
This study showed that:
- HOV lanes do provide an incentive to use shared-rides. Fifteen to 18 percent (depending of type of travel) of HOV lane users during the peak commuting periods, and 18 to 23 percent of HOV lane users during the mid-day, reported they would switch to solo driving if the HOV lanes were not available. Due to survey methodology this finding is considered conservative and probably represents the minimum number of users likely to switch to solo driving with long-term or permanent closure of the HOV lanes.
- HOV lane closure would impact both freeways and side streets, and lengthen peak commuting hours. Approximately 26 percent of carpoolers said they would continue carpooling, but switch to driving either on a different route (19%) or on the same route during different hours (7%) if HOV lanes were no longer available.
- People choose shared rides for reasons other than time savings and reliability. Users cited saving time and money, reduced stress, and convenience as the main reasons they use the HOV system.
- Most carpools are composed of household members, and these “family pools” behave very similarly to standard carpools. Without HOV lanes, both family-pools and standard carpools would be expected to switch to single-occupant driving at approximately the same rate. Less than half of both types of carpools reported they would continue carpooling without HOV lanes.
- Ride-sharing is a choice. Almost 99% of HOV lane users have at least one working vehicle in their household, and 80% have two or more. Driving alone to work is common one day a week or more for a large percentage of HOV lane users.
- Employer incentives play a large role in the decision to take shared-rides. 87% of bus riders and vanpoolers, and 24% of carpoolers, use employer rideshare incentives such as free bus passes, discounted parking, flextime, etc. Without those incentives, between 40–60% (depending on type of travel) would either stop ride-sharing, or are not sure how they would travel.
- 70% of mid-day carpooling is for work, shopping, or appointments/meetings. That is, carpoolers are in the HOV lanes during the mid-day for purposes other than transporting children from school or to recreational activities.
Read a downloadable version of the final report (pdf 1.5 mb).
Updated September 2009.