I-405/Brickyard to SR 527 Improvement Project

Project overview

The I-405/Brickyard to SR 527 Improvement Project enhances four and a half miles of the corridor, primarily in Bothell, from just south of the State Route 522 interchange and ending at the SR 527 interchange. WSDOT, Sound Transit and design-build contractor Skanska USA Inc., will deliver improvements that benefit all users, while addressing aging infrastructure, opening upstream fish habitat, and connecting communities, freight and Regional Growth Centers throughout the corridor.

Since implemented in 2015, express toll lanes (ETL) have helped improve reliability of trips on the north end of the I-405 corridor, however the single-lane section still experiences heavy congestion, especially for people traveling south during the morning commute. The project will extend the dual-express toll lane system on the north end of I-405 and improve access to the voter-approved Stride bus rapid transit service to address congestion and help keep all vehicles moving efficiently.

This project includes three new Stride stations and will build direct access ramps to the ETL system at SR 522, along with a partial direct access interchange at SR 527 to and from the south connecting to the Canyon Park Park & Ride. These enhancements will allow Stride vehicles to travel in the new ETLs between Lynnwood and Bellevue while stopping briefly to pick-up and drop-off passengers without having to leave the highway system. Having dedicated ETL access in the center of the freeway will make travel more efficient supporting the new Stride service with buses arriving every 10 minutes for most of the day.

Additionally, the project will address aging infrastructure, correct multiple fish barrier corrections, add noise walls and add new stormwater facilities.

What to expect

Spring 2024, we broke ground on this project and kicked off construction. Watch video highlights from the event. 

Reminder to slow down to 35 MPH

WSDOT has started a pilot Work Zone Speed Limit Camera program. This program will be coming to the project as early as April 28, with a camera placed first on eastbound SR 522, before the I-405 interchange. The location of the speed camera may be adjusted throughout the project. Please slow down on SR 522 near the I-405 interchange for the safety of constructions crews and the traveling public.

Overnight lane reductions and rolling slowdowns on southbound I-405 near SR 527 for sign removal, May 21-22

Overnight lane reductions on southbound I-405 between State Route 527 and Northeast 195th Street will start as early as 10 p.m. Wednesday, May 21, through 4 a.m. Thursday, May 22. Rolling slowdowns will occur during these closures, after 11:59 p.m. During a rolling slowdown, crews temporarily stop traffic for up to 15 minutes to create a gap in the traffic flow which will allow short term access to the roadway to remove a sign bridge over I-405 between SR 527 and Northeast 195th Street.

Crews may close the following ramps during this work:

• Southbound I-405 to SR 527
• Northbound SR 527 on-ramp to southbound I-405
• Southbound SR 527 on-ramp to southbound I-405

Detours will be in place during the ramp closures to direct drivers around the active work on southbound I-405. Drivers should expect additional traffic on southbound I-405 approaching Bothell during overnight work and plan for delays.

Sammamish River Trail Reroute and brief closures

In order to complete work safely next to the Sammamish River Trail and move equipment, crews will need to continue to close it temporarily. Trail users can expect brief closures for the duration of the project which is scheduled to be complete in Spring 2028. 

What to expect 

There will be a short reroute around the active work zone underneath the I-405/SR 522 interchange. Brief weekday, daytime closures of the trail will occur no longer than 15 minutes per closure and no more than 45 minutes total per day. 

• Closures will occur intermittently between the hours of 9 a.m. and 3 p.m., and overnight between 7 p.m. and 5 a.m.
• Signage along the trail ahead of the reroute will direct you where to go. Flaggers will be present during closures to direct traffic. 

Overnight closures will not take place during the weekends, except on select weekends with prior notice. Please take caution when travelling along the trail outside of daytime hours. Construction activities are ongoing in the area to build the foundation for the new northbound I-405 ramp bridge to eastbound SR 522. Crews will conduct this work during daytime hours.  Trail users can expect nighttime closures in mid-June when crews set girders for the new I-405 ramp bridge.