HOV lanes

High occupancy vehicle (HOV) lanes, also known as carpool or diamond lanes, are special-use highway lanes reserved for carpools, vanpools, buses and motorcycles. Express toll lanes and High Occupancy Toll (HOT) lanes are used by those vehicles, and allow other traffic to pay a toll to use the lanes. In Washington these lanes connect major population and employment centers, forming a crucial part of the central Puget Sound area's highway system.

The 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. Enough demand exists for peak period freeway space that the HOV lane would quickly become just another clogged lane if HOV lanes were opened to all traffic all the time.

WSDOT has various types of HOV, HOT and express toll lanes on Interstate 5, Interstate 90, Interstate 405, State Route 16, State Route 520, and State Route 167.

HOV lanes

HOV lanes are identified by the diamond symbol on signs along the highway and painted on the pavement. They are typically separated from the other lanes on the highway by a solid white line. To travel in an HOV lane a vehicle must meet the occupancy requirements listed on the signs when HOV rules are in force. Motorcycles are also allowed to use HOV lanes.

Express toll lanes and High Occupancy Toll (HOT) lanes

The I-405 Express Toll Lanes and SR 167 HOT Lanes are a form of HOV lane that can also be used by non-HOV drivers who choose to pay a toll. Drivers who do not qualify as a carpool have the choice to pay a toll for a faster trip when they need it. Toll rates adjust every few minutes based on real-time traffic conditions to keep traffic in these lanes moving.

Carpool rules for SR 167 HOT Lanes

Carpools with two or more people can always use the SR 167 HOT Lanes for free. A Good To Go! pass or account is optional for carpools on SR 167, but if you do have a pass in your vehicle, make sure it is a Flex Pass set to HOV mode to travel toll-free.

Carpool rules for I-405 Express Toll Lanes

Carpools with enough passengers can use the express toll lanes for free with a Good To Go! Flex Pass. The carpool occupancy requirement depends on the time of day.

Monday through Friday

No carpool or pass is needed to drive for free on nights or weekends.

Motorcycles can also use the I-405 Express Toll Lanes for free with a Good To Go! motorcycle pass (optional in the SR 167 HOT lanes).