SR 509: Completion Project

Phase 1 Improvements

Online Environmental Re-Evaluation Open House


The Puget Sound Gateway Program is comprised of two projects, SR 167 Completion Project and SR 509 Completion Project, which together will make major improvements to freight mobility and relieve traffic congestion throughout the Puget Sound Region. The Gateway Program is key to enhancing the state’s economic competitiveness, both nationally and globally, by connecting the state’s largest ports to key distribution centers in King and Pierce counties, and to Eastern Washington.



Alaska Airlines plane take off Seatac

Completing the Gateway Program provides more direct links from the state’s largest ports to the distribution centers in the region and to Eastern Washington. The program provides direct access to Seattle-Tacoma International Airport from the south for both passenger and air cargo.

The SR 509 Completion Project is a critical missing link in the state’s highway network. SR 509 improves transportation connections between urban and manufacturing centers in south King County for people and goods. Extending SR 509 will ease congestion on I-5, create another access point to Sea-Tac International Airport, and improve service between industrial districts by allowing freight and traffic to bypass I-5, SR 99 and local streets.

Explore the Project