Nightly I-5 lane and SR 509 ramp closures in south King County will continue this Thursday through Saturday, July 27

Multiple lanes and ramps will continue closing overnight on I-5 and SR 509 in the SeaTac, Des Moines and Kent area from July 18-27, as crews working for the Washington State Department of Transportation (WSDOT) perform utility work.

Crews will also close lanes on local roads in the area to perform soil testing and build road improvements.

This work is part of the SR 509 Completion Project.

In addition, beginning Sunday, July 21 Sound Transit crews will close the right lane of southbound I-5 for approximately two weeks to install drainage along I-5, as part of the Federal Way Link Extension project.

I-5 lane closure information

Thursday, July 18 through Friday, July 19:

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

Sunday, July 21 through Monday, August 5:

• 10 p.m. – The right lane on southbound I-5 will close around the clock between South 259th Street and South 272nd streets.

Monday, July 22 through the morning of Thursday, July 25:

• 11:30 p.m. to 6 a.m. – Up to two lanes of southbound I-5 will close overnight between South 200th Street/Military Road South (Exit 151) and SR 516 (Exit 149).

Wednesday, July 24 through the morning of Thursday, July 25:

• 9:30 p.m. to 4 a.m. – Up to three lanes of northbound I-5 will close overnight between SR 516 (Exit 149) and South 200th Street/Military Road South (Exit 151).

SR 509 ramp closures

Wednesday, July 24 through the morning of Friday, July 26:

• 9 p.m. to 8 a.m. – The southbound SR 509 on-ramp from South 160th Street will be closed. A signed detour will be in place.

Friday, July 26 through the morning of Saturday, July 27:

• 9 p.m. to 5 a.m. – The southbound SR 509 on-ramp from South 160th Street will be closed. A signed detour will be in place.

Daytime local road closures

Monday, July 22 through the morning of Saturday, August 2:

• 7 a.m. to 3 p.m. – One lane of South 208th Street and one lane of 34th Avenue South will close. Flaggers will alternate traffic.

Nighttime local road closures

Monday, July 22 through the morning of Wednesday, July 24:

• 8 p.m. to 5 a.m. – One lane of South 192nd Street will close between Des Moines Memorial Drive South and First Avenue South. Flaggers will alternate traffic.
• 9 p.m. to 4 a.m. – One lane of South 188th Street will close between Eighth Avenue South and Des Moines Memorial Drive South.

Wednesday, July 24 through the morning of Thursday, July 25:

• 9 p.m. to 4 a.m. – One lane of South 188th Street will close between Eighth Avenue South and Des Moines Memorial Drive South.

Thursday, July 25 through the morning of Friday, July 26:

• 8 p.m. to 5 a.m. – One lane of Des Moines Memorial Drive South will close between South 194th and South 196th streets. Flaggers will alternate traffic.

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 by 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.