Road or highway · United States
How much does Washington State Route 509 cost?
Washington State Route 509 is being completed by the Puget Sound Gateway Program, which builds three new miles of tolled expressway between I-5 and the airport end of SR 509 in King County, with Stage 1a finished in 2022, the first mile opening in June 2025 and the final two miles scheduled to open in 2028–2029. WSDOT funds the Gateway Program at $2.83 billion for the SR 509 and SR 167 Completion Projects together, up from $1.96 billion at launch in 2019, and the SR 509 Stage 2 design-build contract with Atkinson and Jacobs is worth $478.8 million.
Published project estimate
$2.83 billion
Cost basis: 2025
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Cost evidence
Basis of the published figure
Published project estimate2025
Project metrics
Key dimensions
- Total lengthWSDOT
- 4,828 m
Project record