…In King County, SR 509, which currently ends at South 188th Street, will be extended to I-5. The extension will have two lanes in each direction. A new interchange will be built at S. 188th St.
The Washington State Department of Transportation said extending 509 will serve as an alternative to I-5, SR 99 and local streets. It will also create a new southern access point to Sea-Tac Airport.
“By completing SR 167 and SR 509, we are closing two of the state’s major transportation gaps. But these aren’t just WSDOT projects,” said Secretary of Transportation Roger Millar. “Eighteen local jurisdictions want to see these projects completed and have shown their support by contributing $130 million towards their construction.”
Both projects are expected to be completed in 2028.
Watch WSDOT videos about the projects below and find more information about the Puget Sound Gateway Program here.