Nightly I-5 and daytime road closures in south King County continue next week

Overnight lane closures on I-5 in the SeaTac, Des Moines and Kent area will continue Monday, Sept. 30 through Friday, Oct. 4, 2024, the Washington Department of Transportation (WSDOT) announced.

The closures will allow contractor crews to perform electrical work. Crews will also close lanes on local roads in SeaTac for road improvements and soil testing.

This work is part of the State Route 509 Completion Project.

I-5 lane and ramp closure information

Monday, Sept. 30 through the morning of Wednesday, Oct. 2:

• 11:59 p.m. to 3:30 a.m. – Up to four lanes of northbound I-5 will close nightly between SR 516 (Exit 149) and South 200th Street/Military Road South (Exit 151).
• 11 p.m. to 3:30 a.m. – The SR 516 on-ramp to northbound I-5 will close.

Wednesday, Oct. 2 through the morning of Friday, Oct. 4:

• 11:59 p.m. to 6 a.m. – Up to four lanes of southbound I-5 will close nightly between South 200th Street/Military Road South (Exit 151) and SR 516 (Exit 149).

Local road closure information

Monday, Sept. 30 through Friday, Oct. 4:

• 7 a.m. to 3 p.m. – One lane of 33rd Avenue South in SeaTac will close daily. Flaggers will alternate traffic.

Thursday, Oct. 3 through the morning of Saturday, Oct. 5:

• 7 p.m. to 5 a.m. – One lane of South 208th Street in SeaTac will close overnight. Flaggers will alternate traffic.

An interactive project map that allows people to explore the new SR 509 Expressway, the SR 516 interchange and other elements of the completion project is also available online.

SR 509 Stage 2 Online Open House

People who live in, work in, or travel through Burien, Des Moines, SeaTac, or Kent can visit the SR 509 Stage 2 online open house to learn more about current and planned construction. The online open house runs through Oct. 25.

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 currently under construction between I-5 and 24th Avenue is scheduled to open in 2025. The final stage will build the remaining 2 miles of the expressway between 24th Avenue South and South 188th Street. The entire project is planned for completion in 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. Combined, the two completion projects finish critical missing links in Washington’s highway and freight network.

Know before you go

Before heading out the door, travelers can find the latest information on the WSDOT app, the real-time travel map, or by subscribing to WSDOT’s email and text alerts.