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Research Reports

HOV Lane Enforcement Evaluation


This study evaluated various high occupancy vehicle (HOV) lane enforcement techniques on a recently constructed section of HOV lanes along I-405 in the Seattle, Washington, area. The research included a related public opinion survey concerning HOV lanes. The enforcement techniques that were evaluated included intensive (or continuous saturation) enforcement, once a week saturation enforcement, and once a week stationary enforcement.

This study concluded that each type of enforcement effort helped in lowering the number of HOV lane violations; however, it was not possible to determine which method was most effective. Violations decreased considerably during the first weeks of enforcement, regardless of the type of enforcement.

The public opinion survey indicated that, in general, the public supports the concept of HOV lanes. Eighty-six percent of the respondents felt that HOV lanes were a good idea. At the same time, 55 percent indicated that existing HOV lanes were not being used enough. Almost 60 percent of the respondents believed HOV lane violations were common during the commute hours. Almost the same percentage (58 percent) believed that HOV lane violators were seldom caught by enforcement agencies. A higher percentage of the respondents (71 percent) believed HOV violations increased when the Washington State Patrol was not visible along the HOV lane.

The research team recommends intensive enforcement only for the first three months (or less) of the operation of a new HOV facility. After that point, the level of effort should revert to routine enforcement.

This study also makes recommendations concerning the design of HOV lanes related to enforcement issues. Specifically, enforcement areas alongside HOV lanes must be designed in cooperation with the appropriate enforcement agency. Two types of enforcement areas along freeways are suggested.


  • Date Published: January, 1993
  • Publication Number: WA-RD 281.1
  • Last Modified: October 12, 2007
  • Authors: Cy Ulberg, Eldon L. Jacobson.
  • Originator: Washington State Transportation Center (TRAC)
  • # of Pages: 65 p., 1,340 KB (PDF)
  • Subject: Data collection, Evaluation, High occupancy vehicle lanes, High occupancy vehicles, Public opinion, Recommendations, Surveys, Traffic law enforcement, Traffic violations.
  • Keywords: HOV, high occupancy vehicle, enforcement, public opinion, HOV enforcement, HOV lane design, I-405, Seattle (Wash.)
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This abstract was last modified April 29, 2008