Drivers in the Seattle area should prepare for significant traffic delays this weekend as several major roadways will experience closures and lane reductions. The Washington State Department of Transportation (WSDOT) and Sound Transit are conducting critical maintenance and construction projects on I-90, I-405, I-5, and SR 16. These closures are expected to cause considerable congestion, particularly during peak travel times.
Key Takeaways
- Eastbound I-90 at Mercer Island will have three lanes closed for 16 days, impacting Lake Washington crossings.
- Westbound I-90 over Lake Washington will close overnight Friday for tunnel maintenance.
- Westbound I-90 in Issaquah faces lane reductions and ramp closures for bridge work through Sunday morning.
- The westbound I-90 off-ramp to SR 18 will close from Friday night to Monday morning for guardrail installation.
- Southbound I-405 in Bellevue will have lane reductions and ramp closures for widening project work.
- Northbound I-5 off-ramp to NE 130th Street will close for Pinehurst Station construction.
- East Roanoke Street on Capitol Hill will be closed Saturday and Sunday for utility work.
- Westbound SR 16 at the Tacoma Narrows Bridge will see two right lanes closed for expansion joint repair.
Extended Eastbound I-90 Lane Closures at Mercer Island
WSDOT is continuing work on the East Channel Bridge, a project initiated after an expansion joint failed in January 2024. This current phase involves repairing multiple expansion joints. The work will reduce a one-mile stretch of eastbound I-90 between East Mercer Way and Bellevue Way to three lanes.
This lane reduction began recently and is scheduled to continue through October 5. Traffic backups are common, often extending into Seattle during busy periods. Drivers traveling across Lake Washington may need to use SR 520 as an alternative route.
Traffic Impact
The I-90 East Channel Bridge project is expected to cause backups similar to those seen during the emergency closure in early 2024. During that period, traffic delays stretched for miles, highlighting the critical nature of this corridor.
Overnight Westbound I-90 Closure Over Lake Washington
Regular maintenance operations will take place inside the Mercer Island and Mount Baker tunnels. Following last week's eastbound closure, crews will now focus on westbound I-90.
All westbound lanes between Island Crest Way and Rainier Avenue South will close. The closure starts Friday, September 19, at 10 p.m. and is expected to end by 6 a.m. on Saturday, September 20. This overnight work aims to ensure the safety and structural integrity of the tunnels.
Westbound I-90 Lane Reductions in Issaquah
Bridge work on westbound I-90 in Issaquah will cause significant lane closures. Starting Friday, September 19, at 8 p.m., two left lanes will be closed for a one-mile stretch at Front Street. The Front Street on-ramp will also be inaccessible during this period.
This work is scheduled to conclude by 8 a.m. on Sunday, September 21. Further lane reductions for bridge repairs are planned for two additional weekends: tentatively September 26-28, and a second weekend after the October 4-5 Issaquah Salmon Days festival.
"Drivers should plan for extra travel time and consider alternative routes, especially during peak hours. These projects are essential for maintaining our infrastructure, but they will impact commutes," a WSDOT spokesperson stated.
Westbound I-90 Off-Ramp to SR 18 Closure
The westbound I-90 off-ramp to SR 18/Snoqualmie Parkway will close for guardrail and curb installation near Snoqualmie. This closure begins at 9 p.m. Friday, September 19, and will last until 5 a.m. Monday, September 22.
A detour will guide westbound I-90 drivers. They will need to loop around at Preston/Fall City (exit 22) and use the eastbound I-90 off-ramp to SR 18/Snoqualmie Parkway. This work is part of the I-90/SR 18 Interchange Improvements project, which also includes widening SR 18 to two lanes in each direction between I-90 and Deep Creek. The overall project is expected to finish later this fall.
Project Background
The I-90/SR 18 Interchange Improvements project aims to enhance traffic flow and safety in the area. It includes a new diverging diamond interchange, a modern traffic management solution designed to improve efficiency and reduce collision points at busy intersections.
Southbound I-405 Lane Reductions in Bellevue
The I-405/Renton to Bellevue Widening and Express Toll Lanes Project requires significant work this weekend. WSDOT crews will remove pavement, excavate, perform sewer repairs, and pave new sections.
From 11 p.m. Friday, September 19, to 4:30 a.m. Monday, September 22, southbound I-405 will have lane reductions from NE 70th Place to I-90. Additionally, the southbound I-405 on-ramps at NE 70th Place and SE Eighth Street will close. Signed detours will be in place to guide drivers around these closures.
Northbound I-5 Off-Ramp to NE 130th Street Closed
Sound Transit crews will close the northbound I-5 off-ramp to Northeast 130th Street. This closure starts at 10 p.m. Friday, September 19, and will last until 5 a.m. Monday, September 22. The work supports the construction of the Pinehurst Station, part of the Lynnwood Link Extension project.
The Lynnwood Link Extension project is a major expansion of the light rail system. The Pinehurst Station is scheduled to open in 2026, providing new transit options for the community.
- Friday, Sept. 19, 10 p.m. – Monday, Sept. 22, 5 a.m.: Northbound I-5 off-ramp to NE 130th Street closed.
- Purpose: Construction of Pinehurst Station for Lynnwood Link Extension.
- Impact: Drivers will need to use alternative exits and routes.
East Roanoke Street Closure on Capitol Hill
Drivers on the north side of Capitol Hill will not be able to access East Roanoke Street just east of the freeway on both Saturday and Sunday. Crews will close East Roanoke Street between Harvard Avenue and 10th Avenue East each day from 7 a.m. to 10 p.m.
Uniformed police officers will be present to manage vehicle and pedestrian traffic. Emergency services will maintain access to the area. Pedestrians and drivers should follow the marked detours. During the two-day closure, crews will trench and install an underground conduit system, preparing for future utility relocation.
Westbound SR 16 Lane Closures at Tacoma Narrows Bridge
The Tacoma Narrows Bridge requires another repair to address an expansion joint issue in the westbound direction. Beginning at 8 a.m. Friday, September 19, WSDOT crews will close the two right lanes approaching the bridge. The Jackson Avenue on-ramp to westbound SR 16 will also be closed.
During this closure, the HOV lane will be open to all drivers. All lanes are scheduled to reopen by 10 p.m. Saturday, September 20. After the expansion joint repair, new concrete will be poured. The concrete needs time to cure, which means lane closures might remain even when no active work is visible.
Drivers should anticipate congestion on westbound SR 16 as they approach the bridge, especially during Friday afternoon's commute. It is advisable to allow for extra travel time or consider postponing non-essential trips to avoid delays. These infrastructure repairs are crucial for the long-term safety and functionality of the bridge.
