SR 522 traffic shifts at I-405 as crews make progress reshaping the interchange

By Lauren Penning

In the last year, crews have made rapid progress reshaping the interchange at SR 522 and I-405. Now we are ready to move to the next phase of construction on the I-405 Brickyard to SR 527 Improvement Project. This means traffic needs to shift on SR 522 at the I-405 interchange.

Map showing where crews will shift traffic on SR 522 at I-405.

What to expect while we do the shift

Starting at 11:59 p.m., Friday, April 18 to 6 a.m., Saturday, April 19:

• SR 522 will be a single lane each direction at I-405
• Westbound SR 522 ramp to northbound I-405 closed with signed detour in effect

Drivers should slow down as they approach the work zone. Watch for changing traffic control as crews shift eastbound and westbound traffic to the newly paved section of SR 522 further north.

Progress on Par Creek fish passage
This shift means traffic will move over the newly completed section of the Par Creek fish passage. This fish passage will run under SR 522 at I-405. We completed the first section of the fish passage in late 2024. Since then, westbound SR 522 ramp traffic has been traveling over that new section. Now we’ve completed the second portion of the passage and are ready to shift traffic again. This will free up space to begin construction on the south portion.

Opening of the second phase of the Par Creek fish passage in February 2025. The blue line shows where the fish passage will connect. Traffic will now be shifted on top of the fish passage, opening up a new area to continue work.

The Par Creek fish passage will connect the Sammamish River with Par Creek, allowing for natural stream processes that help protect and restore salmon runs. In total, this project will remove six fish barriers and create new habitat area.

Reminder to slow down to 35 MPH

A year ago, we reduced the speed limit on SR 522 near the I-405 interchange from 60 to 35 MPH. We made this permanent change for the safety of our crews. This speed limit also reflects how drivers will navigate this road in the future.

Despite this change, our crews still regularly see traffic speeding through the area. They often see drivers far exceeding the posted speed limit. We are asking drivers to slow down on SR 522 near the I-405 interchange for the safety of our crews and all travelers.

New route to SR 522 from northbound I-405 coming in late 2025
This project adds direct access to the I-405 express toll lanes (ETLs) at the SR 522 interchange. These ramps will be available for HOV and ETL users and Sound Transit Bus Rapid Transit (BRT). It also provides infrastructure to support BRT service along I-405. These new connections mean changes to the I-405/SR 522 interchange.

Key Changes:

• New traffic signal in late 2025 will control two movements :
• Eastbound SR 522 to northbound I-405: New left turn at signal, no more loop ramp.
• Northbound I-405 to west SR 522: Use new signal, no more flyover ramp.
• More signals: Two more added by 2028.

Important Dates:

• First signal: November 2025
• Project completion: 2028

Expect ongoing updates before each major change.

A map of the final configuration of the SR 522 interchange. You can see three new traffic signals marked. These allow for access to the new direct access ramps to the express toll lanes and Stride station. Please note, this is a conceptual design, and details are subject to change.

Thank you for your patience as we continue this work. Improvements to this 4.5 mile stretch of I-405 through Bothell will benefit drivers, riders, and many other travelers. Check out the WSDOT real-time travel map for up-to-date information. If you have any questions and/or you would like to sign up for project updates, please email I405SR167Program@wsdot.wa.gov. Stay informed by subscribing to WSDOT updates for King County.