Lane and ramp closures on SR 509 in SeaTac and Burien continue Wednesday, Feb. 18 to the morning of Thursday, Feb. 19, according to the Washington State Department of Transportation (WSDOT).
These closures will allow WSDOT crews to perform drainage and electrical work.
This work is part of the SR 509 Completion Project.
SR 509 lane closure information
Wednesday, Feb. 18 to the morning of Thursday, Feb. 19:
- 8 p.m. to 5 a.m. – One lane in each direction of SR 509 will close overnight between South 176th and South 188th streets.
SR 509 ramp closure information
Wednesday, Feb. 18 to the morning of Thursday, Feb. 19:
- 9 p.m. to 5 a.m. – The northbound SR 509 off-ramp to South 160th Street will close overnight. A signed detour will be in place.
SR 509 Completion Project information
The SR 509 Completion Project builds 3 miles of new tolled highway between I-5 and South 188th Street near the south end of Seattle-Tacoma International Airport. The new highway will be completed in stages. The portion between I-5 and 24th Avenue South opened on June 28, 2025 and a new tunnel under I-5 at the SR 516 interchange opened on July 16, 2025. The final stage builds the remaining 2 miles of the expressway between 24th Avenue South and South 188th Street. The entire project is planned for completion by 2029.
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.
