Dept. of Transportation
Metro Transit Division

King Street Center
201 S Jackson St
Seattle, WA 98104
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Your Guide to Diamond Lanes

Carpools, vanpools, buses and motorcycles are the only vehicles allowed to use the diamond lanes. Generally, these HOV lanes require two-person carpools, but there are some roadways that require a minimum of three. Diamond lane requirements are in effect 24 hours a day, unless posted otherwise.

In some areas, where the diamond lane is the far right lane, commuters exiting from the freeway will need to travel a short distance in that lane to reach the exit ramp. However, general traffic may only cross into the diamond lane where there is dashed lane striping. It may not cross where there is a solid line, otherwise a ticket may be issued.

Some of the Puget Sound freeway on-ramps are metered with traffic lights that control the flow of traffic entering the freeway. A few of the ramp meters in the region have HOV bypass lanes. These are diamond lanes on the ramp that allow carpools, vanpools, and buses to bypass the ramp meter and the traffic waiting to enter the freeway. Generally, ramps are metered from 6:00 to 9:00 a.m. and from 2:30 to 7:00 p.m.

Check out the Washington State Department of Transportation's HOV lane site [external link] for more information on HOV lanes.

The WSDOT HERO Program [external link] operates a 24-hour telephone hotline (764-HERO), which accepts and processes reports of observed violations of the HOV lanes and ramps.