I-405 Express Toll Lanes - Why Express Toll Lanes

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Watch a short video about why rates change.

Why express toll lanes?
The previous I-405 HOV lanes were often as congested as the regular lanes and failed to reduce traffic or provide shorter travel times to carpools and transit. The express toll lanes offer faster, more predictable trips. 

How do tolls keep traffic moving?
Toll rates are based on real-time traffic conditions. Every five minutes, the traffic management computer system updates toll rates based on how many cars are in the lanes and how fast they are going. The goal is to use the laws of supply and demand to keep traffic moving.

When traffic is flowing smoothly and there is plenty of room in the express toll lanes, the price is low to encourage cars to get in. When the lanes start to fill up and slow down, the price goes up in order to discourage too many cars from getting in so that the lanes can keep flowing efficiently. 

How do express toll lanes reduce congestion?
Before the express toll lanes were built congestion in every lane was getting steadily worse every year, but the express toll lanes reversed that trend in most parts of I-405. Now, the regular lanes are moving as fast or faster than they did two years ago. 

Chart showing average speeds in I-405 regular lanes increased by up to 7 miles per hour faster after express toll lanes opened.

When traffic is at its worst, express toll lanes are the most efficient lanes on I-405. At the height of the peak commute, each express toll lane moves up to 30 percent more cars than a regular lane in some locations. When drivers choose to leave the regular lanes to use the express toll lanes instead, they free up space for the other drivers around them.

Where does the money go?
About two-thirds of toll revenue is used to fund improvements to I-405 like the northbound peak use shoulder lane between SR 527 and I-5 which opened to the public in April 2017. Read more about where toll rate money goes.

History of I-405 express toll lanes
The I-405 express toll lanes are the result of more than nearly two decades of planning and coordination between the state and local communities along the I-405 corridor. In 1999, WSDOT began work with the public, employers, cities, counties, and regional planning agencies to develop the I-405 Master Plan. In 2002, the I-405 Executive Advisory Group which included representatives from cities along the corridor adopted this master plan. In 2011, the state Legislature authorized express toll lanes on this stretch of I-405. The express toll lanes opened on Sept. 27, 2015. Read a detailed project history.