I-405 - SR 522 to SR 527 Capacity Improvements Project

Project news

  • Preliminary engineering is currently underway, funded in part with express toll lane revenue.
  • This project is not currently funded for right of way or construction.

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 to SR 527 Capacity Improvements 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.

Proposed design concept for the I-405/SR 522 interchange Proposed design concept for 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 and Timeline

This project is fully funded for engineering and environmental review stages, with a total of $20 million in funding during the 2017-19 and 2019-21 biennia.

  • 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.”

An additional $20 million is needed for right-of-way acquisition, and an estimated $450 million is needed for construction.

WSDOT is evaluating potential funding and phasing approaches and continuing to work with stakeholders to prioritize project elements with the most benefits for I-405 travelers.

Katie Kuciemba Halse
I-405/SR 167 Corridor Communications
425-456-8663
halsek@consultant.wsdot.wa.gov

I-405, SR 522 to SR 527 Capacity Improvements Project map