SEATTLE - Travelers throughout the Puget Sound region should prepare for another busy weekend of construction as work on all three major north-south corridors takes place Aug. 14-17.

Closures and lane reductions are scheduled on Interstate 405 in Tukwila and Kirkland, and State Route 99 and I-5 in Seattle. The most notable impacts include:

• Lane reductions on southbound I-405 approaching I-5 in Tukwila.
• Full closure of the I-405/Northeast 85th Street interchange in Kirkland.
• Closures on portions of SR 99.
• Continued two-lane configuration on northbound I-5 across the Ship Canal Bridge.

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 and check conditions for their entire trip before leaving.

Southbound I-405 lane closures in Tukwila

Up to two lanes of southbound I-405 will close between SR 181 and I-5 from 11:30 p.m. Friday, Aug. 14 to 4 a.m. Monday, Aug. 17. The southbound I-405 HOV ramp to northbound I-5 will also close.

Travelers should expect delays at the ramp to northbound I-5 and for travelers heading to Seattle-Tacoma International Airport. Crews will work on paving the HOV lane as part of the I-405/Renton to Bellevue Widening and Express Toll Lanes Project.

I-405/Northeast 85th Street interchange closures in Kirkland

The northbound and southbound I-405 on- and off-ramps at Northeast 85th Street (Exit 18) in Kirkland will close from 10 p.m. Friday, Aug 14 to 5 a.m. Monday, Aug. 17. Northeast 85th Street between Sixth Street to 120th Avenue Northeast will also close.

Detours will be in place. Crews will grade pavement on Northeast 85th Street and install curbs as part of the I-405/Northeast 85th Street Interchange and Inline BRT Station Project.

SR 99 closures in Seattle, Aug. 14-17

The SR 99 tunnel will close in both directions overnight from 10 p.m. Friday, Aug. 14 to 6 a.m. Saturday, Aug. 15 for routine tunnel maintenance.

Northbound SR 99 will close at the First Avenue South Bridge from 5 a.m. Saturday, Aug. 15 to 11:59 p.m. Sunday, Aug. 16 for bridge and structure preservation. Travelers will not be able to access East Marginal Way or Michigan Street from the First Avenue South Bridge or continue northbound on SR 99 during the closure.

Additional closures include:

• Occidental Avenue South/South Kenyon Street connection to northbound SR 99.
• West Marginal Way South/South Holden Street connection to northbound SR 99.
• First Avenue South connection to northbound SR 509.

Revive I-5: Ship Canal Bridge Preservation project

Northbound I-5 in Seattle is reduced to two lanes across the Ship Canal Bridge until the end of 2026. 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.

Plan ahead

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 work moves around the region.

People should 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 King County email updates.