Drivers in the Seattle metropolitan area face multiple lane closures and traffic disruptions across major highways this week and into early October. The Washington State Department of Transportation (WSDOT) and Sound Transit are conducting critical maintenance and construction projects on I-90, I-405, I-5, SR 16, and local streets. These projects are expected to cause significant delays, especially during peak travel times.
Motorists should plan for extra travel time and consider alternative routes or transportation methods. Key areas affected include Mercer Island, Bellevue, Issaquah, Snoqualmie, and Tacoma, with work extending from bridge repairs to tunnel maintenance and express toll lane construction.
Key Takeaways
- Eastbound I-90 at Mercer Island will have reduced lanes until October 5 for expansion joint repairs.
- Westbound I-90 will close overnight over Lake Washington on September 19 for tunnel maintenance.
- Additional weekend lane reductions are scheduled for westbound I-90 in Issaquah and the SR 18 off-ramp.
- Southbound I-405 will see lane reductions in Bellevue from September 19-22 for widening and express toll lane work.
- The northbound I-5 off-ramp to NE 130th Street will close for Sound Transit's Lynnwood Link Extension project.
- Westbound SR 16 at the Tacoma Narrows Bridge will experience lane closures for expansion joint repairs.
Eastbound I-90 Lane Reductions Near Mercer Island
WSDOT crews are continuing work on the East Channel Bridge on I-90 near Mercer Island. This project addresses a failed expansion joint first identified in January 2024. The repairs require a one-mile stretch of eastbound I-90, between East Mercer Way and Bellevue Way, to be reduced to three lanes.
This reduction is scheduled to last for 16 days, with an estimated completion date of October 5. Drivers should expect substantial traffic backups, similar to those experienced during the emergency closure earlier this year. Congestion is likely to begin in Seattle during peak commute hours. State Route 520 will serve as the primary alternative route across Lake Washington during this period.
Traffic Impact Fact
The eastbound I-90 lane reduction at Mercer Island is expected to cause backups starting in Seattle, making SR 520 the main alternative for crossing Lake Washington.
Overnight Westbound I-90 Closure Over Lake Washington
WSDOT will close all westbound lanes of I-90 between Island Crest Way and Rainier Avenue South for essential maintenance. This work includes operations inside the Mercer Island tunnel and the Mount Baker tunnel. The closure begins at 10 p.m. on Friday, September 19, and lanes are expected to reopen by 6 a.m. on Saturday, September 20.
This follows a similar eastbound closure conducted last Friday. Drivers should plan for this overnight disruption and seek alternative routes if traveling westbound across Lake Washington during these hours.
Westbound I-90 Bridge Work in Issaquah
Drivers heading west through Issaquah on I-90 will encounter lane closures for bridge repairs. Starting at 8 p.m. on Friday, September 19, two left lanes will close for a one-mile stretch at Front Street. The Front Street on-ramp will also be closed during this time.
This initial phase of work is scheduled to conclude by 8 a.m. on Sunday, September 21. WSDOT plans two additional weekends of single-lane reductions for westbound I-90 in Issaquah to continue these bridge repairs. The first of these additional weekends is tentatively set for September 26-28. The second will occur after the Issaquah Salmon Days festival, which takes place on October 4-5.
"Drivers should expect to see congestion on westbound SR 16 approaching the bridge during the lane closures, and significant congestion approaching the bridge during the afternoon commute Friday, Sept. 19. Drivers should add extra travel time to help prevent delays or consider combining or postponing discretionary trips."
Westbound I-90 Off-Ramp to SR 18 Closed
The westbound I-90 off-ramp to State Route 18 (SR 18)/Snoqualmie Parkway will be closed from 9 p.m. on Friday, September 19, until 5 a.m. on Monday, September 22. This closure is necessary for guardrail installation and curb work near Snoqualmie.
During the ramp closure, westbound I-90 drivers needing to access SR 18 will follow a detour. This detour involves looping around at Preston/Fall City (Exit 22) and then using the eastbound I-90 off-ramp to SR 18/Snoqualmie Parkway. This work is part of the larger 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 Context
The I-90/SR 18 Interchange Improvements project aims to enhance traffic flow and safety. It includes a new diverging diamond interchange and widening SR 18, with completion anticipated this fall.
Southbound I-405 Lane Reductions in Bellevue
Southbound I-405 will experience lane reductions in Bellevue for work related to the I-405/Renton to Bellevue Widening and Express Toll Lanes Project. These reductions will be in effect from 11 p.m. on Friday, September 19, to 4:30 a.m. on Monday, September 22, specifically from NE 70th Place to I-90.
During this period, several southbound I-405 on-ramps will also close. These include the on-ramps at NE 70th Place and SE Eighth Street. Drivers will be directed by a signed detour route around these closures. Crews will perform pavement removal, excavation, sewer repairs, and paving to support the project.
- Closed On-Ramps:
- Southbound I-405 at NE 70th Place
- Southbound I-405 at SE Eighth Street
Northbound I-5 Off-Ramp Closure at NE 130th Street
Sound Transit crews will close the northbound I-5 off-ramp to Northeast 130th Street. This closure begins at 10 p.m. on Friday, September 19, and ends at 5 a.m. on Monday, September 22. The work supports the construction of the Pinehurst Station, which is part of the Lynnwood Link Extension project.
The Lynnwood Link Extension project is a significant infrastructure development aimed at expanding light rail service. The Pinehurst Station is scheduled to open in 2026. Drivers should plan for detours and potential delays when accessing NE 130th Street from northbound I-5 during this weekend.
East Roanoke Street Closure on Capitol Hill
East Roanoke Street on the north end of Capitol Hill will be closed just east of the freeway on both Saturday, September 20, and Sunday, September 21. Crews will close the 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 guide vehicle and pedestrian traffic around the closure. Access for emergency services will be maintained. Drivers and pedestrians must follow the signed detours. During the two-day closure, crews will trench and install an underground conduit system for future utility relocation, an essential step for infrastructure upgrades in the area.
Westbound SR 16 Lane Closures at Tacoma Narrows Bridge
The Tacoma Narrows Bridge requires additional repairs to address an expansion joint issue on the westbound side. Starting at 8 a.m. on Friday, September 19, WSDOT crews will close the two right lanes approaching the bridge, along with the Jackson Avenue on-ramp to westbound SR 16.
During this closure, the High Occupancy Vehicle (HOV) lane will be open to all drivers. All lanes are scheduled to reopen by 10 p.m. on Saturday, September 20. After the expansion joint repair, crews will pour new concrete. The concrete needs time to cure, meaning lane closures may remain in place even if no active work is visible.
Drivers should anticipate congestion on westbound SR 16 approaching the bridge, particularly during the Friday afternoon commute. It is advisable to allow extra travel time or consider postponing non-essential trips to avoid delays.
