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Washington State Freeway HOV System

HOV lanes are high-occupancy vehicle lanes that are reserved for carpools, vanpools, buses, motorcycles or any vehicle carrying two or more people. They are also known as carpool or diamond lanes. The HOV system consists of a network of special-use highway lanes which connect major population and employment centers. It forms a crucial part of the central Puget Sound area's highway system.

HOV lanes are designed to maximize the movement of people rather than vehicles. They usually move more people than a general purpose lane, even when they don't look full. For example, you may only see one bus per minute, but buses can carry the equivalent of 45 or more cars.

Studies show that HOV lanes encourage commuters to travel together. Many people who do not usually drive alone on the freeway during rush hours would switch to solo freeway driving if the HOV lanes were opened to all traffic – including many of the people who are currently riding the bus, carpooling, and vanpooling. Enough demand exists for peak period freeway space to quickly result in just another clogged lane if HOV lanes were opened to all traffic all the time.

WSDOT has various types of HOV lanes on Interstate 5, Interstate 90, Interstate 405, State Route 16, State Route 167 and State Route 520:

Standard HOV Lanes
Standard HOV lanes are generally inside (left) lanes and are identified by signs along the highway and diamond symbols painted on the pavement. They are typically separated from the other lanes on the highway by a solid white line. The HOV lane requirement is either 2+ or 3+ persons per vehicle, depending on the highway and/or time of day. Motorcycles are allowed to use all standard HOV lanes.

Express Toll and High-Occupancy Toll Lanes
Express toll and high-occupancy toll (HOT) lanes are HOV lanes open to vehicles that do not meet HOV lane requirements if drivers pay a toll. Vehicles that meet the HOV lane requirement (2+ or 3+ depending on the highway and/or time of day), can use these lanes for free with a proper Good To Go! pass. HOT and express toll lanes let drivers choose a more reliable trip by paying a toll. Toll rates adjust depending on real-time conditions to ensure traffic in the HOV lanes are free flowing. Motorcycles are allowed to use express toll lanes with a proper Good To Go! pass, but do not need one to use HOT lanes.