Project Facts
- Completes the SR 509 corridor by building over 3 miles of new freeway.
- Includes new SR 509 interchange access at S. 200th St., the proposed Sea-Tac Airport South Access roadway, and SeaTac's new 24th/28th Ave. S. corridor.
- Builds new lanes on I-5 between S. 210th and S. 272nd Street vicinity, including new connections and interchange reconstruction at SR 516.
August 2008
- 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 will be used towards continued property acquisition, further advancing the design, acquiring environmental permits and early establishment construction of the project wetland mitigation site.
- Limited property acquisition and relocations continue 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 Will the Initial Phase include?
The Initial Phase will construct a four-lane road between South 210th Street and South 188th Street in SeaTac and Burien, provide a new I-5/SR 509 interchange, and add collector/distributor lanes to I-5 from South 210th Street to SR 516.
The I-5/SR 516 interchange will be rebuilt, including a new connection to South S. 231st Way. New General Purpose lanes will be added to I-5 from the SR 516 interchange to S. 320th street interchange. A new direct access to Sea–Tac Airport from SR 509 will 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. This results in a public benefit of approximately $5 for every dollar spent in delivering this project.
What is the project timeline?
2005 - 2007
- Obtain state and federal permits required for construction.
- Continue design work on the Initial Phase.
- Continue property acquisition and related relocations and structure demolition.
- 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.
Public Involvement
Your thoughts and opinions are important to us. Thank you for providing input during the planning and design phases of this project. We appreciate your patience during construction and so do the private contractors who do the construction work. For further information, contact the project office.
Environmental Protection
WSDOT has fulfilled its commitment by completing the project Final Environmental Impact Statement (FEIS). The FEIS was issued to the public on January 22nd, 2003, and the Record of Decision (ROD) was signed by the Federal Highway Administration (FHWA) on March 20th, 2003. Design work is underway in an effort to be ready for construction upon receipt of additional funding.
The project design team (consisting of WSDOT project office and environmental staff along with consultant staff) has been exploring every opportunity to avoid and minimize impacts to the environment. The project design will preserve the existing environment, as well as make improvements over current conditions. These efforts included:
- Working with environmental agencies to make changes to the proposed SR 509 extension alignment to reduce impacts to wetlands, streams, and neighboring homes and businesses.
- Making contributions to water quality and basin improvements in the Des Moines Creek Basin Plan.
- Meeting the most current stormwater treatment standards.
Please visit the
WSDOT Environmental
Services Web site for more information.
Increasing safety is one of our priorities
Increasing capacity and improving traffic flow reduces the risk of accidents. During construction, WSDOT will implement all necessary traffic management and safety measures.
Will this project impact tribal resources?
At WSDOT we seek to address the concerns of the tribal nations using the process outlined in Section 106 of The National Historic Preservation Act and the WSDOT Tribal Consultation Policy adopted in 2003 by the Transportation Commission as part of the WSDOT Centennial Accord Plan.
Tribal consultation with the Muckleshoot, Duwamish, Puyallup and Suquamish Tribes and Lummi and Yakama Nations has resulted in a finding of non-significant impact to tribal resources.
Financial Information
The 2007 cost estimate for the SR 509 Initial Phase is $1,078 million dollars. This is part of the estimated total project cost, which is $1.35 billion. 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.
This project is funded 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
• 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:
Paul Johnson, Project Engineer
WSDOT Corson Ave. Project Office
6431 Corson Ave. S., MS-61
Seattle, WA 98108
Phone: 206-768-5680
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