Project news

• Preliminary engineering is currently underway, funded in part with express toll lane revenue.

Overview

I-405 is one of the most congested corridors in the state, serving an area that is exceeding regional population growth estimates.

The express toll lanes between Bellevue and Lynnwood have helped improve traffic and provided new transportation options for the north end of the I-405 corridor. There are currently two express toll lanes in each direction between NE Sixth Street in Bellevue and just south of the SR 522 interchange in Bothell, and a single lane between SR 522 and I-5. This single-lane section continues to experience congestion, particularly southbound in the morning commute, because there is not enough roadway capacity to keep up with demand. 

Consistent with the long-term Master Plan for the corridor, WSDOT is moving forward with additional improvements to address increasing traffic congestion and improve transit reliability in Bothell and south Snohomish County.

Scope

The I-405, SR 522 Vicinity to SR 527 Express Toll Lanes Improvement Project would:

• Widen I-405 through the SR 522 interchange and build direct access ramps to the express toll lanes at SR 522
• Extend the dual I-405 express toll lane system between SR 522 and SR 527 (build one new lane in each direction)
• Build a partial direct access ramp at SR 527 (to east, north and south) to provide connections to the Canyon Park Park and Ride

The images below show the proposed design concepts for the I-405/SR 522 interchange and the I-405/SR 527 interchange.

Overall, these improvements will help support a reliable trip for travelers in all lanes, including riders of Sound Transit’s new I-405 Bus Rapid Transit system, planned to open in 2024.

Funding & timeline

In 2019, the Legislature fully funded this project through their direction to use toll revenue and bonding.

• 2016: Legislature allocated $200,000 for a study of potential improvements to the area between SR 522 and I-5. WSDOT coordinated with stakeholders, including local cities and transit agencies, to identify a phased approach to addressing congestion in this area.
• 2017: $5 million allocated from I-405 program savings to continue preliminary engineering for the first phase of improvements between SR 522 and SR 527.
• 2018:  Additional $15 million in express toll lane revenue approved in Supplemental Transportation Budget “for activities related to adding capacity on Interstate 405 between state route number 522 and Interstate 5, with the goals of increasing vehicle throughput and aligning project completion with the implementation of bus rapid transit in the vicinity of the project.”
• 2019: Legislature authorized up to $600 million to design and construct the capacity improvements between SR 522 and SR 527.
• 2021: Start of construction; anticipated three to four year construction period.