Overnight lane and ramp closures on I-5 and SR 509 in the SeaTac, Des Moines and Kent area will continue next week, from Monday, Sept. 9 through Saturday, Sept. 14, 2024.
The closures will allow contractor crews to remove temporary scaffolding from the new northbound I-5 flyover ramp to the future SR 509 expressway.
Crews will also close lanes on local roads in the area for utility work and soil testing.
This work is part of the SR 509 Completion Project.
I-5 lane closure information
Monday, Sept. 9 through the morning of Wednesday, Sept. 11:
- 9:30 p.m. to 4 a.m. – Up to three lanes of northbound I-5 will close nightly between SR 516 (Exit 149) and South 200th Street/Military Road South (Exit 151). Drivers may encounter a rolling slowdown.
- 11 p.m. to 6 a.m. – Up to three lanes of southbound I-5 will close nightly between South 200th Street/Military Road South (Exit 151) and South 272nd Street (Exit 147).
Wednesday, Sept. 11 through the morning of Friday, Sept. 13:
- 9:30 p.m. to 4 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).
I-5 ramp closure information
Monday, Sept. 9 through the morning of Tuesday, Sept. 10:
- 9:30 p.m. to 3:30 a.m. – The northbound I-5 off-ramp to SR 516 will close. A signed detour will be in place.
Wednesday, Sept. 11 through the morning of Friday, Sept. 13:
- 11:30 p.m. to 4 a.m. – The southbound I-5 off-ramp to SR 516 will close. A signed detour will be in place.
SR 509 lane closure information
Friday, Sept. 13 through the morning of Saturday, Sept. 14:
- 8 p.m. to 5 a.m. – One lane in each direction of SR 509 will close between South 160th Street and Des Moines Memorial Drive.
Local road closure information
Monday, Sept. 9 through Friday, Sept. 13:
- 7 a.m. to 3 p.m. – One lane of South 208th Street in SeaTac will close daily. Flaggers will alternate traffic.
Tuesday, Sept. 10 through Friday, Sept. 13:
- 8 a.m. to 4 p.m. – One lane of Kent-Des Moines Road between 16th Avenue South and South 230th Street close daily. Flaggers will alternate traffic.
- 8 a.m. to 4 p.m. – One lane of South 223rd Street between 13th Avenue South and 16th Avenue South will close daily. Flaggers will alternate traffic.
An interactive project map is also available that allows people to explore the new SR 509 expressway, the SR 516 interchange and other elements of the completion project.
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.