What are rules for using carpool lanes in Washington state? How to avoid fines
You’re stuck in traffic on a highway in a Washington state when your eyes drift over to the carpool lane.
Those vehicles are moving more freely, and likely getting to their destinations quicker.
You might be tempted to sneak over in
What are the requirements for using carpool lanes in Washington? And what happens if you break the rules?
Here’s what to know:
How do carpool lanes work in Washington state?
High occupancy vehicle lanes are “special-use highway lanes reserved for carpools, vanpools, buses and motorcycles,” the Washington Department of Transportation said on its website.
These lanes, also known as carpool lanes or diamond lanes are “designed to maximize the movement of people and encourage commuters to use transit or travel together to save time, reduce traffic volumes and congestion,” the state agency said.
They’re used to “move as many people through congested areas of traffic as quickly as possible,” according to Colburn Law, which has offices in Issaquah and Seattle.
“Enough demand exists for peak period freeway space” that carpool lanes would quickly become clogged if they were open to “all traffic all the time,” the state Transportation Department said.
You can identify a carpool lane by the diamond symbol printed on signs along the highway and painted on the pavement.
High-occupancy vehicle lanes usually separated from other lanes on the roadway by a solid white line.
You can find these lanes on Interstate 5, Interstate 90, Interstate 405, State Route 16, State Route 520 and State Route 167, along with express toll lanes.
What are express toll lanes?
Express toll lanes on I-405 and State Route 167 allow drivers to speed up their trips — for a fee.
“Toll rates change based on real-time traffic conditions, and range between $1 and $15,” the Washington State Department of Transportation said.
You can also get a Good To Go! pass for $5 to $12.
What are carpool lane requirements in Washington state?
Signs designating high-occupancy vehicle lanes typically indicate the number of occupants you need to have in your car, pickup truck or SUV.
That number includes the driver, plus any passengers.
“A passenger is any other human occupant inside of the vehicle aside from the driver,” including infants and children, Washington State Trooper Kameron Watts told McClatchy Media via email. “Dummies, pets and dolls do not count.”
Motorcycles can use carpool lanes regardless of the number of people they’re carrying.
There are exemptions for school buses and tour buses as well as emergency vehicles, tow trucks and public transportation.
How can I drive in express toll lanes for free?
Carpools with two or more people can use State Route 167 express toll lanes for free with a Good to Go! flex pass, state transportation officials said.
“No carpool or pass is needed to drive for free between 8 p.m. and 5 a.m.,” the state Transportation Department said.
Carpools with enough passengers can use I-405 express toll lanes for free with Good To Go! passes, with vehicle occupancy requirements depending on the time of day.
From 5 to 9 a.m. Monday through Friday, vehicles must have three or more occupants in order to use express toll lanes, according to the Washington State Department of Transportation.
You’ll need two or more people in your car to use I-405 express toll lanes from 9 a.m. to 3 p.m. weekdays.
Three or more occupants are required to use those lanes from 3 to 8 p.m. on weekdays.
You don’t need a carpool or pass to “drive for free on nights or weekends,” state transportation officials said.
Motorcyclists with Good To Go! passes can ride in express toll lanes for free.
Can I use the carpool lane in an emergency?
Washington state law doesn’t specify whether you can use carpool lanes without meeting vehicle occupancy requirements in the case of an emergency, Watts said.
“In the event you are pulled over, inform the officer or trooper of the emergency at hand so it can be handled accordingly,” said Watts, a public information officer for the Washington State Patrol.
Can I use the carpool lane to pass a car?
Now, you cannot use the carpool lane as a passing lane, according to Watts.
Instead, use the left lane closest to the carpool lane to overtake slower vehicles.
What are penalties for breaking carpool rules?
“Violating HOV rules can be expensive and becomes increasingly more expensive with repeated violations,” the Washington State Department of Transportation said.
The fine for a first-time offense is $186.
“All subsequent violations within a two-year period increase to $336,” the state Transportation Department said. “If a doll or dummy is placed in the car, an additional $200 will be added to the fine.”
This story was originally published April 27, 2026 at 5:00 AM with the headline "What are rules for using carpool lanes in Washington state? How to avoid fines."