Drivers should expect nighttime lane and ramp closures on I-5, SR 509 and local roads in Burien, SeaTac and Kent from Tuesday, Sept. 8 to the morning of Friday, Sept. 11, according to the Washington State Department of Transportation (WSDOT).
The lane closures on I-5 will allow WSDOT contractor crews working for the to perform drainage work.
The lane and ramp closures on SR 509 will allow crews to perform landscape work and build structures for highway signs.
The local road closures will allow crews to haul in soil needed to build the new SR 509 Expressway.
This work is part of the SR 509 Completion Project.
I-5 lane closure information
Tuesday, Sept. 8 to the morning of Friday, Sept. 11:
- 10 p.m. to 6 a.m.: Up to two lanes of southbound I-5 will close nightly from SR 516 (Exit 149) to South 272nd Street (Exit 147).
SR 509 lane closure information
Thursday, Sept. 10 to the morning of Friday, Sept. 11:
- 8 p.m. to 5 a.m.: One lane of southbound SR 509 will close overnight from South 168th Street to South 176th Street.
SR 509 ramp closure information
Tuesday, Sept. 8 to the morning of Friday, Sept. 11
- 9 p.m. to 5 a.m.: The South 188th Street on-ramp to northbound SR 509 will close nightly. A signed detour will be in place.
Thursday, Sept. 10 to the morning of Friday, Sept. 11:
- 9 p.m. to 5 a.m.: The South 160th Street on-ramp to southbound SR 509 will close overnight. A signed detour will be in place.
Local road closure information
Tuesday, Sept. 8 to the morning of Thursday, Sept. 10:
- 8 p.m. to 5 a.m.: South 200th Street will close nightly in both directions from 18th Avenue South to just east of the Des Moines Creek Trail. Signed detours will be in place.
SR 509 Completion Project information
South 188th Street near the south end of Seattle-Tacoma International Airport. The new highway will be completed in stages. The first mile between I-5 and 24th Avenue South opened in June 2025. Construction of the final 2 miles between 24th Avenue South and South 188th Street is underway and currently scheduled to open to traffic in July 2028.
Photos of construction work and a 3D video tour are available online.
Puget Sound Gateway Program overview
The SR 509 Completion Project is part of WSDOT’s Puget Sound Gateway Program, which also includes the SR 167 Completion Project in Pierce County. Together, the two completion projects finish critical missing links in Washington’s highway and freight network.
