November 2009
- Final landscpe work is under way.
- WSDOT crews opened all lanes to traffic in early June 2009. Air travelers are now enjoying faster trips from the airport with fewer backups.
- WSDOT thanks the Port of Seattle for contributing $10 million in funding to the project.
- Minor work left to complete includes landscaping and placement of traffic monitoring technology, such as traffic data sensors and video cameras.
- WSDOT awarded the contracts for the SR 518 – Sea-Tac Airport to I-5 / I-405 Interchange and the SR 509/518 Interchange Improvement projects to Tri-State Construction, Inc.
- The federal government has contributed $5.6 million to the project.
Why is WSDOT
undertaking the SR 518 Sea-Tac Airport to I-5/I-405 Interchange Project?
SR 518 is becoming a progressively more popular connection between SR 509 and I-5/I-405. This increase in traffic, combined with forecasts calling for significant air travel growth over the coming years, will dramatically impact SR 518. If improvements aren't made to eastbound SR 518, drivers traveling the corridor will encounter difficult merge conditions, and drivers leaving Sea-Tac Airport can experience more than 30-minute delays, with lines of cars projected to back up nearly to the airport garage.
The End Result
The SR 518 Sea-Tac Airport to I-5/I-405 Interchange Project improves existing mobility and safety and accommodates projected airport traffic by adding a third eastbound lane on SR 518 between the North Airport Expressway and the I-5/I-405 Interchange.
The project also provides for further regional improvements, including Sound Transit's Link light rail line extension to the airport and the Airport traffic and parking enhancements slated for completion in 2006, which are both dependent on the SR 518 improvements.
Project Benefits
• Congestion Relief
The project will reduce airport congestion and delays. Adding a third lane on SR 518 will allow better traffic flow during airport and freeway rush hours and will yield travel time savings at the airport ramps that currently experience backups.
• Safety
Adding a third eastbound lane on SR 518 will improve and simplify the merging from the North Airport Expressway on the west end of the project as well as access to the entrances to I-5 and I-405 on the east end of the project.
• Environmental Benefits
The proposed project will make beneficial improvements to existing conditions. Noise walls will be installed to reduce traffic noise for neighborhoods. Runoff from the highway will be treated to enhance overall water quality conditions. Detention facilities and stormwater treatment will be provided to protect Gilliam Creek.
What is the project timeline?
Spring 2006
The Environmental Assessment (EA) was published on May 30, 2006.
Summer 2006
The Environmental Assessment (EA) and Finding of No Significant Impact (FONSI) were approved by the Federal Highway Administration (FHWA).
Spring 2007
Project design completed.
The EA and FONSI were issued under the National Environmental Policy Act (NEPA) and adopted under the State Environmental Policy Act (SEPA) rules.
Summer 2007
Construction begins.
WSDOT has awarded the contracts for the SR 518 – SeaTac Airport to I-5 / I-405 Interchange and the SR 509/518 Interchange Improvement projects to Tri-State Construction, Inc.
Construction has begun at the SR 509/518 interchange including preliminary environmental work, erosion control and traffic control.
Summer 2009
Project opens to traffic.
Financial Information
The project is funded through the following sources:
- 2005 Gas Tax - $20 Million
- The Port of Seattle - $10 Million
- The Federal Government - $5.6 Million
Total Funding Available from all sources - $35.6 Million
\
How can I get more information?
Contact:
Mark Sawyer, P.E.
Construction Project Engineer
WSDOT Urban Corridors Office
Phone: 425-649-4429
Paul E. Johnson, P.E.
Design Project Engineer
WSDOT Urban Corridors Office
Phone: 206-768-5680
Noel S. Brady
Public Information Officer
401 2nd Ave. S, Suite 200
Seattle, WA 98104
Phone: 206-464-1183
back to top