UPDATE: Sept. 17, 2026 - Please note the I-405/Northeast 85th Street interchange closure scheduled for Sept. 18-21 and the eastbound I-90 lane and ramp closures in Bellevue scheduled for Sept. 18-20 are cancelled until further notice. Advance notice will be provided when the work is rescheduled. The news release is updated below.
Expect congestion and delays on I-405, I-5 and SR 520
SEATTLE – Travelers should plan for longer travel times getting around the Puget Sound region during the Sept. 18-21 weekend. The Washington State Department of Transportation will have highway construction closures on Interstate 405, I-5 and State Route 520.
Travelers should be prepared for:
- A full closure of northbound I-405 from Renton to Bellevue.
- Continued two-lane configuration on northbound I-5 across the Ship Canal Bridge in Seattle.
- Lane closures on eastbound SR 520 over Lake Sammamish Parkway in Redmond.
The work is spread across the region, but the effects overlap as travelers adjust routes and traffic shifts between highways and local streets. People should expect congestion, allow more time to travel and check conditions for their entire trip before heading out.
Northbound I-405 closure from Renton to Bellevue
All lanes of northbound I-405 will close from North Southport Drive in Renton to Coal Creek Parkway Southeast in Bellevue from 11:30 p.m. Friday, Sept. 18, to 4 a.m. Monday, Sept. 21.
Crews will work on drainage, paving and a traffic switch as part of the I-405/Renton to Bellevue Widening and Express Toll Lanes Project. A northbound detour will be in place with signs directing travelers along the way.
Travelers should also be alert and aware of northbound lane reductions along the state detour route on Coal Creek Parkway Southeast as part of King County’s Coal Creek Sewer Upgrade Project work.
Northbound I-5 lane closures across Ship Canal Bridge in Seattle continue
Northbound I-5 in Seattle is reduced to two lanes across the Ship Canal Bridge until the end of 2026 as part of the Revive I-5 Ship Canal Bridge Preservation project. The express lanes will remain open northbound-only 24 hours a day. The Harvard Avenue on-ramp to northbound I-5 is closed until mid-October.
Eastbound SR 520 closures over Lake Sammamish Parkway in Redmond
Bridge maintenance crews will close the two right lanes of eastbound SR 520 over Lake Sammamish Parkway in Redmond from 5 a.m. to 1 p.m. Saturday, Sept. 19, and Sunday, Sept. 20, for repair work.
Plan ahead for widespread delays
Travelers should expect longer and less predictable trips. Delays may occur in new places and at new times, and conditions may change week to week as construction work moves around the region during the good weather window needed for much of this work.
To help ease congestion and delays, people can use transit and park-and-ride options, be flexible about travel times and access real-time traffic information. Drivers should slow down, stay alert and follow posted signs when approaching and traveling through work zones. These choices can make a meaningful difference during major closures and help keep both travelers and highway crews safe.
Much of this work requires good weather and may be rescheduled due to rain. Schedule updates will be available on WSDOT’s online Travel Center map, the WSDOT mobile app and by signing up for WSDOT’s King County email updates.