TagGateway Project(12)

This interlocal agreement between the Washington State Department of Transportation (WSDOT) and the City of SeaTac outlines a cooperative arrangement for road improvements on S. 204th Street between 32nd and 34th Avenues South, as part of the SR 509 Completion Project near Sea-Tac International Airport. WSDOT agreed to assign the construction work in that corridor to the City of SeaTac and reimburse the city up to $1,641,318 upon substantial completion. After construction, the City of SeaTac is responsible for maintaining all improvements, including sidewalks, lighting, and stormwater facilities.

A June 2024 WSDOT presentation to the Des Moines Historical Society outlines the SR 509 Completion Project, part of the broader Puget Sound Gateway Program alongside the SR 167 Completion Project in Pierce County. The project aims to improve freight and passenger connections between the Port of Seattle, Sea-Tac Airport, and key regional distribution centers in King County. The presentation covers the project's history and two construction stages, with WSDOT emphasizing efficiencies gained by managing both highway projects under a single program.

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.

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.

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.

The Puget Sound Gateway Program, presented at a Highline Forum in September 2018, outlines two highway completion projects—SR 509 in King County and SR 167 in Pierce County—designed to improve freight movement between the ports of Seattle and Tacoma and key distribution centers. Among its key benefits, the program includes a new south access point to Sea-Tac Airport and aims to reduce congestion on local roads surrounding the airport. Funding for the program combines state, local, federal, and toll revenue sources, with electronic tolling on all new lanes expected to begin as early as 2025.

The City of SeaTac entered into an interlocal agreement (Agreement No. 18-A144) with the Washington State Department of Transportation (WSDOT) to provide up to $4,000,000 in local matching funds for the construction of the Puget Sound Gateway Program, specifically the State Route 509 Extension Project. The funding is split into two stages: up to $2,000,000 in real estate and/or cash for the SeaTac Access Local Nexus Project, and up to $2,000,000 in cash toward the South 188th Street Interchange once construction sales tax is received. WSDOT is responsible for designing, constructing, and managing the project, which includes improvements such as interchange ramps and access roads largely within the City of SeaTac.