November 2009
- Road construction costs have risen steeply over the past two years, so WSDOT has changed its plan for building the I-5/SR 509 project. The new plan is to complete the work in phases. WSDOT would construct key parts of the project and deliver many benefits to citizens in the initial phase. Construction of other parts of the project would be delayed until funding is available. Read the latest newsletter (pdf 1.1 mb).
- The 2005 Transportation Partnership Program budget included $30 million in new funding for the project. This was used for property acquisition, further advancing the design, acquiring environmental permits and early establishment construction of the project wetland mitigation site.
- Limited property acquisition and relocations were made utilizing $15 million provided through the nickel funding package.
Why is WSDOT
extending SR 509?
Extending SR 509 will ease congestion on I-5, improve service between industrial districts by allowing general-purpose traffic and up to 9,000 trucks per day to bypass I-5, SR 99 and local streets, and provide for southern access to Sea-Tac International Airport.
What does the Initial Phase include?
The Initial Phase includes constructing a four-lane road between South 210th Street and South 188th Street in SeaTac and Burien, providing a new I-5/SR 509 interchange, and adding collector/distributor lanes to I-5 from South 210th Street to SR 516.
The I-5/SR 516 interchange would be rebuilt, including a new connection to South S. 231st Way. New south-bound Collector Distributor lanes would be added from the new I-5/SR509 interchange to S. 320th street interchange. A new direct access to Sea–Tac Airport from SR 509 would be provided at South 200th Street along with a new connection to the SeaTac business district at 24th/28th Avenue South.
The End Result
When finished, SR 509, the South Airport Access roadway, and new I-5 lanes and improvements will become a key component within 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.
View a map of the project area.
Project Benefits
- Congestion. Reduces congestion on I-5 in South King County by providing an alternate north-south route to I-5 while increasing I-5 capacity.
- Safety. Increasing capacity and improving traffic flow reduces the risk and frequency of accidents.
- Freight. Provides 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 direct connection between I-5 and Sea-Tac Airport from the south.
- Public Value. By reducing travel times between Seattle and Tacoma by up to 12 minutes, the traveling public saves more than $100 million per year in travel time.
What is the project timeline?
2005 - 2009
- Obtain state and federal permits required for construction.
- Completed design work on the Initial Phase.
- Completed property acquisition and related relocations and structure demolition with available funding.
- Continue utility coordination efforts and relocation planning.
For more detailed project schedule information, please visit the schedule page, or contact the project office with schedule-related questions.
Financial Information
The 2008 cost estimate for the SR 509 Initial Phase is $1.177 billion to $1.337 billion dollars. This latter estimate includes funds spent to date, the $35 million in new funding received as part of the 2003 Nickel" funding package and the $30 million in new funding received as part of the 2005 "TPA" funding package. The cost estimate range depends on when funding becomes available and inflation.
This project received funding through the following sources:
- 2005 Gas Tax -$30 Million
- 2003 Gas Tax - $35 Million
- Other Funds - $21 Million
Pre-existing State, Federal, and other
Partnership Funds.
- Total Funding Available from all sources - $86 Million
- Total amount not funded - $1.091 to $1.251 billion
Voters in King, Pierce and Snohomish counties did not approve Proposition 1, which included some funding for this project as part of the 2007 Regional Transportation Investment District Blueprint for Progress. Other sources of money for this project have not been identified.
How can I get more information?
Contact:
Jason Biggs, Acting Project Engineer
WSDOT Corson Ave. Project Office
6431 Corson Ave. S., MS-61
Seattle, WA 98108
Phone: 206-768-5680
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