We’ve begun using the term “Fourth Runway” to describe two large projects (SR-509 and the Sustainable Airport Master Plan) as one system, which they are. The two projects have always been part of a regional plan begun over fifty years ago to meet the strategic goals of the Port Of Seattle and regional planners. The construction of SR-509 will affect the communities are great deal. But starting in 2027 the projects will also increase flight operations at least 33% and cargo operations by 300%.
This map depicts the Washington State SR-509 extension project, showing three construction stages: Stage 1a (at Toll Point near S 208th St), Stage 1b (along I-5 through Kent), and Stage 2 (connecting Burien via Des Moines Memorial Drive to the existing Lake to Sound Trail). The map also identifies future Sound Transit stations, Barnes Creek Wetland mitigation, the Des Moines Creek Trail, and the Lake to Sound Trail under construction near Sea-Tac Airport.
2022-03-24
This is a Washington State Joint Aquatic Resources Permit Application (JARPA) submitted by the Washington State Department of Transportation (WSDOT) for the SR 509 Stage 2 Project, which involves constructing a new expressway between 24th Avenue South and South 188th Street in the cities of Burien, Des Moines, and SeaTac, King County. The project corridor runs through publicly owned land and spans multiple sections of townships near Sea-Tac Airport. The application was received on March 24, 2022, and covers permits related to aquatic resources affected by the highway construction.
A WSDOT aerial planning map dated 11/6/2021 showing the proposed SR 509 New Expressway alignment (red lines) relative to Des Moines Creek Trail Park, with project boundaries (dashed black lines), wetland areas, contour elevations, and adjacent features including an Amazon Warehouse and the City of SeaTac boundary. The document is labeled 'For Discussion Purposes Only' and is part of the Puget Sound Gateway Program involving SR 509, I-5, and SR 167.
A WSDOT engineering plan sheet dated 11/06/2021 showing the proposed SR 509/24th Ave S to S 188th St new expressway alignment through the Blueberry Lane neighborhood, straddling the City of Des Moines and City of SeaTac boundary. The map identifies right-of-way limits (red hatching), stormwater treatment ponds, wetlands, the Lake-to-Sound Trail, and nearby landmarks including The Hub Shopping Center and Sonic Collision Center, produced under the Puget Sound Gateway Program.
A project staging map shows the SR 509 extension and I-5 connector route divided into Stage 1a (toll point near Des Moines Memorial Drive), Stage 1b (along Military Road S toward Kent), and Stage 2 (extending northwest toward Burien and southeast toward Kent via SR 99). The map covers the Des Moines, SeaTac, Burien, and Kent areas of Washington State, with route numbers 99, 509, 316, and 5 visible.
2021-12-20
This WSDOT Puget Sound Gateway Program document presents preliminary design plans for a new SR 509 expressway segment running from 24th Ave S to S 188th St through the Blueberry Lane neighborhood, spanning the cities of Des Moines and SeaTac. The plans show proposed roadway construction, stormwater treatment ponds, wetland areas, and several buildings and roads slated for demolition to accommodate the new highway alignment. Cross-sectional diagrams illustrate the elevation changes and right-of-way boundaries relative to existing neighborhoods, trails, and local streets.
2021-11-17
A November 2021 WSDOT presentation outlines the SR 509 Completion Project, part of the broader Puget Sound Gateway Program, which aims to build new highway connections linking the region's ports and distribution centers between 2020 and 2028. The project includes several construction stages covering new expressway segments, interchange improvements at I-5/SR 516, and a Lake to Sound Trail component in the area south of Seattle near Sea-Tac Airport.
2021-11-17
The Highline Forum held a virtual meeting on November 17, 2021, hosted by the City of SeaTac, covering transportation updates including WSDOT's SR 509 project, Sound Transit developments, and a StART (Sea-Tac Airport Roundtable) update from the Port of Seattle's Aviation Director. The meeting was conducted via Microsoft Teams with no physical location, and public comments were accepted by email or through the online platform. The agenda also included planning for six bimonthly Highline Forum meetings scheduled throughout 2022, running from January through November.
2021-11-04
This WSDOT discussion document from November 2021 shows a planning map for the SR 509 Puget Sound Gateway Program's new expressway project, spanning from 24th Ave S to S 188th St near Des Moines Creek Park in the City of SeaTac. The map highlights the proposed highway alignment (shown in red) running adjacent to Des Moines Creek Trail Park, identifying wetland areas, contour elevations, and nearby features such as an Amazon warehouse and the Lake to Sound Trail. The project represents a major infrastructure expansion in the SeaTac area that would affect the Des Moines Creek Park corridor and surrounding natural resources.
2022-03-24
2021-12-20
2021-11-17
2021-11-17
2021-11-04