Puget Sound freeway HOV lanes have proven to be highly efficient. They move approximately 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 prime commuting hours. For this reason, the WSDOT has invested heavily in the development, maintenance and expansion of HOV freeway lanes.
HOV lanes support the use of carpools, buses, and vanpools, and are therefore a crucial component of offering more sustainable transportation alternatives to solo driving under the current freeway system. Because HOV lanes result in fewer vehicle trips being made on the area’s overall transportation system, they help to reduce greenhouse gas emissions, the primary culprit behind climate change.
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? Are most carpools made up of people from the same household who would be driving together anyway? Do people mostly use the HOV lanes to commute back and forth to work, or do other trip purposes form a significant amount of their use? Who is using the HOV lanes during the mid-day and why? This study begins to answer these questions.
To perform this survey, approximately 30,000 written 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 these three user groups.) Respondents mailed the questionnaires back. 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 take 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 very conservative and should be considered the minimum number of users likely to switch to solo driving with long-term or permanent closure of the HOV lanes; the actual number would most likely be higher.
- HOV lane closure would also impact side streets and increase 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. Convenience, saving money and stress reduction are of equal or more importance than time savings for many users.
- Most carpools are composed of household members, and these “family pools” behave very similarly to standard carpools. 62% of am peak, 71% of mid-day, and 71% of pm peak period carpools are family-pools. Less than half of both family-pools and standard carpools reported they would continue carpooling without HOV lanes. Family-pools represent approximately 42% of overall HOV system users (carpools, bus riders, and vanpoolers) during the peak periods.
- 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 all modes.
- 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. 40–60% (depending on type of travel) would either discontinue their mode without incentives, or are not sure.
- 70% of mid-day carpooling is for work, shopping, or appointment/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).