State Route 518
SR 518 is a key limited-access state highway and freight corridor between SR 509 in Burien and I-5/I-405 in Tukwila. SR 518 provides the primary access to Seattle-Tacoma International Airport, carrying more than 70 percent of all passenger and air cargo trips. The route also serves thousands of commuters in South King County.
WSDOT, the Port, and the City of Burien, in cooperation with other cities and Sound Transit, are working together to improve SR 518. In the spring 2009, WSDOT completed Phase 1, which added a third eastbound lane from the airport to I-5/I-405, adding capacity and improving safety. Phase 2 of the project would improve the southbound to eastbound connection from SR 509 to SR 518, and is not yet funded.
