Drivers should expect nighttime lane closures on I-5 in South King County from Monday, Aug. 31 to the morning of Friday, Sept. 4, according to the Washington State Department of Transportation (WSDOT).
The lane closures on I-5 will allow contractor crews working for WSDOT to perform drainage work.
This work is part of the State Route 509 Completion Project.
I-5 lane closure information
Monday, Aug. 31 to the morning of Friday, Sept. 4:
- 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 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 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.
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.
