WSDOT is planning the set of biggest closures of the year to make progress on key transportation projects in the metro area.

Drivers traveling across Lake Washington on State Route 520, through the Interstate 405/SR 167 corridors and on I-5 in Seattle and between Federal Way and Fife should prepare for major closures beginning late Friday, Sept. 27 to early Monday, Sept. 30.

Together these closures form a “monster” traveler challenge – the biggest weekend of Washington State Department of Transportation construction closures for the region this year. Knowing the location of each closure is important for drivers to prepare in advance and make alternate plans to get around the region.

SR 520 closure

The SR 520 closure stretches from I-5 in Seattle to 92nd Avenue Northeast in Clyde Hill on the Eastside and includes all of the associated on- and off-ramps. The SR 520 Trail will also close for bicyclists and pedestrians across the lake. The highway and trail will close at 11 p.m. Friday and reopen at 5 a.m. Monday. Part of the SR 520 Montlake Project, crews will work on lighting and the fire suppression system under the new Montlake lid over SR 520.

Northbound I-405 closure

Northbound I-405 in Renton will be closed from Sunset Boulevard Northeast/Southport Drive (Exit 5) to Coal Creek Parkway Southeast from 11 p.m. Friday to 4 a.m. Monday. The following ramps will also be closed:

Sunset Boulevard Northeast on-ramp (Exit 5).

Northeast 30th Street on- and off-ramps (Exit 6).

Northeast 44th Street on- and off-ramps (Exit 7).

Lake Washington Boulevard Southeast on- and off-ramps (Exit 8).

Coal Creek Parkway off-ramp (Exit 10).

During the closure, contractor crews working for WSDOT will shift northbound traffic onto a new bridge as part of the I-405/Renton to Bellevue Widening and Express Toll Lanes Project. A signed detour will be available. This work requires mostly dry weather and could be rescheduled if it rains.

Southbound SR 167 closure

Southbound SR 167 will be closed in Kent from SR 516 to South 277th Street beginning 11:59 p.m. Friday to 4 a.m. Monday. The following ramps will also be closed:

SR 516 on-ramp to southbound SR 167.

Southbound SR 167 off-ramp to South 277th Street.

Crews will be paving and striping sections of southbound SR 167. A signed SR 167 detour will be in place for this SR 167 Corridor Improvements Project closure. This work requires mostly dry weather and could be rescheduled if it rains.

I-5 overnight closures

Both directions of I-5 between SR 18 in Federal Way and 54th Avenue East in Fife will be closed overnight on Friday, Sept. 27 and Saturday, Sept. 28. Northbound lanes are closed by 10:30 p.m. and southbound lanes by 11 p.m. Lanes begin reopening at 7 a.m. on Saturday with all lanes open by 11 a.m. On Sunday, lanes begin reopening at 8 a.m. with all lanes open by noon.

Travelers headed to the Fife area should use the signed SR 99 detour route. People with destinations other than Fife should consider using regional routes including SR 18, SR 161, SR 167 and SR 512.

During this closure, WSDOT contractor crews will set girders for a new overpass crossing I-5. This work is part of WSDOT’s Puget Sound Gateway Program to complete SR 167.

Mercer Street on-ramps to I-5

The Mercer Street on-ramps to both north and southbound I-5 in Seattle will close beginning at 10 p.m. on Friday and reopen at 5 a.m. Monday. This work is part of the SR 520 I-5 Express Lanes Connection Project. Crews will use the shutdown to pave the ramp and adjacent shoulders.

Know before you go

Detour routes cannot accommodate normal traffic volumes, so people are advised to “know before you go,” travel during off-peak hours or, if possible, delay discretionary travel to help minimize backups. Traffic flow information is available using WSDOT’s real-time travel map.

Resources to stay informed about the project:

SR 520 24-hour construction hotline: 206-775-8885

I-405/Renton to Bellevue Widening and Express Toll Lanes Project 24/7 construction hotline: 425-818-0161

SR 167 Corridor Improvements Project hotline: 425-456-8585

SR 167 Completion Project: 253-220-5009

SR 520 I-5 Express Lanes Connection Project: 206-316-2559