King County
Travel Advisory from the Washington State Department of Transportation.
Lane and Ramp Closures Continue on I-5 and SR 509 in South King County, Oct. 20–25
SEATAC — Drivers in south King County should expect overnight lane and ramp closures on Interstate 5 and State Route 509 from Monday, Oct. 20 through the morning of Saturday, Oct. 25, as crews continue paving and drainage work for the SR 509 Completion Project.
The closures will affect areas in Burien, Des Moines, SeaTac, and Kent. Travelers should plan for extra travel time and follow signed detours.
I-5 Lane Closures
- Monday, Oct. 20 – Tuesday, Oct. 21:
8 p.m. to 4:30 a.m. — Up to two northbound lanes closed overnight between SR 516 (Exit 149) and South 200th Street/Military Road (Exit 151). - Monday, Oct. 20 – Wednesday, Oct. 22:
10 p.m. to 6 a.m. — Up to two southbound lanes closed nightly between South 200th Street/Military Road (Exit 151) and SR 516 (Exit 149).
SR 509 Lane Closures
- Monday, Oct. 20 – Tuesday, Oct. 21:
8 p.m. to 5 a.m. — One northbound lane closed overnight from South 188th Street to South 176th Street. - Wednesday, Oct. 22 – Saturday, Oct. 25:
8 p.m. to 5 a.m. — One lane in each direction closed nightly between South 188th Street and South 176th Street.
SR 509 Ramp Closures
- Monday, Oct. 20 – Tuesday, Oct. 21:
7 p.m. to 5 a.m. — Des Moines Memorial Drive South ramp to northbound SR 509 closed overnight. A detour will be posted. - Tuesday, Oct. 21 – Wednesday, Oct. 22:
10 p.m. to 5 a.m. — Southbound SR 509 exit to South 188th Street closed. A detour will be posted.
About the SR 509 Completion Project
The SR 509 Completion Project is extending SR 509 by three miles, connecting I-5 to South 188th Street near the south end of Seattle-Tacoma International Airport. The project will open in stages, with full completion expected in 2029.
- The section between I-5 and 24th Avenue South opened June 28, 2025.
- A new tunnel under I-5 at the SR 516 interchange opened July 16, 2025.
📸 View construction photos on Flickr
🎥 Watch a 3D video tour on YouTube
🔗 Learn more about the SR 509 Completion Project
About the Puget Sound Gateway Program
The Puget Sound Gateway Program combines the SR 509 and SR 167 Completion Projects to close critical freight and highway gaps in King and Pierce counties. Learn more at the Puget Sound Gateway Program website.
Contact:
Portia Holt, WSDOT Communications
📞 206-293-1699
Issued by:
Washington State Department of Transportation
Puget Sound Gateway Program
999 Third Ave., Suite 2300, Seattle, WA
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