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SR 509 Corridor Completion


June 2016

Thank you to all that attended the SR 509 Open House on December 17, 2015. Materials are now available in the project library.

Over the next few months, project staff will  re-engage project stakeholders, perform a practical solutions review process, and do a re-evaluation of our previously completed environmental document.

Why is WSDOT extending SR 509?

Extending SR 509 will ease congestion on I-5, add a southern access point to Sea-Tac International Airport and improve service between industrial districts by allowing general-purpose traffic and trucks to bypass I-5, SR 99 and local streets.

The End Result
When finished, SR 509 will become a key component of the Seattle and south King County transportation network. When considered in conjunction with the planned Alaskan Way Viaduct improvements, the project provides a critical north-south corridor alternative to I-5 through Seattle and South King County.

Project Benefits

Reduced Congestion. Fewer vehicles and less traffic on I-5 in South King County by providing an alternate north-south route to I-5.
Advanced wetland mitigation. Environmental improvements completed in advance of the project improve water quality and wildlife habitats for the Des Moines Creek basin.
Intermodal freight mobility. Creating a direct route for freight and general traffic movements to and from the Puget Sound marine ports and the industrial areas of Seattle and South King County.
Airport Access. Provides for a new connection between I-5 and Sea-Tac Airport from the south.
Public value. Reduces travel times between Seattle and Tacoma and between the Port of Seattle and the Kent Valley.
Intelligent transportation. In addition to adding revenue, creating a toll road will help manage travel demand to improve system performance.

What is the project timeline?
Funding through the Connecting Washington Account will be distributed over a 16 year period. WSDOT anticipates construction will be complete in 2031.

Financial Information

This project received funding through the following sources:

2005 Gas Tax -$30 million
2003 Gas Tax - $35 million
Other funds - $21 million
(from pre-existing state, federal and other partnerships)
2015 Connecting Washington - $1.9 billion (shared between SR 509 and SR 167)

How can I get more information?
Emily Mannetti, Public Information

Omar Jepperson, P.E.

The Washington State Department of Transportation is a public agency and is subject to the State of Washington’s Public Records Act (RCW 42.56). Therefore, public comments and questions may be made available to anyone requesting them for non-commercial purposes.

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