SR 509 & SR 518 - S 192nd St to Normandy Pk & SR 509 to SR 99 Paving & ADA & Deck & Seismic

Project news

  • As of May 13, 2020, this project has resumed as part of the governor's "Safe Start Washington" (pdf 502 kb) recovery plan. Contractor crews will adhere to a list of 30 safety protocols (pdf 138 kb) and will be required to have site specific safety plans and regular pre-activity meetings to ensure compliance with these standards. 
  • For updated closure information, check the construction webpage
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The pavement on these stretches of state routes 509 and 518 are about 20 years old. With approximately 50,000 vehicles using these major corridors each week, the aging asphalt is cracked and in need of repair. 

Beginning in spring 2019, WSDOT contractor crews will grind and repave both directions of SR 509/1st Avenue South in Normandy Park and SR 518 in SeaTac. They will also upgrade sidewalk ramps on SR 509 and seismically retrofit two bridges on SR 518 and one bridge at the I-405/I-5 interchange.

Needs & Benefits

  • Safety
    • Improving the highway surface eliminates and helps prevent future potholes, cracks and wheel ruts where water can collect. This gives drivers a safer, smoother ride.
    • Reconstructed sidewalk ramps at intersections create better connections for people of all abilities. 
    • Ensuring that the bridges are seismically retrofitted reduces the risk of the overpasses cracking or collapsing during an earthquake. 
  • Preservation
    • Grinding and repaving improves the driving surface and extends the life of the highways. 
    • Retrofitting helps reduce potential damage to the bridges in the event of an earthquake by strengthening the columns and crossbeams that support the bridged sections.
  • Economic
    • Repaving reduces the need for emergency repairs, which are costly and cause additional congestion, particularly during peak commute hours. 
    • Seismically retrofitting the bridges helps reduce the risk that travelers and commerce will be disrupted after an earthquake. 


  • November 2018: Project was advertised for competitive bidding.
  • January 2019: Project was awarded to Massana Construction Inc.
  • March 2019: Construction began.
  • Spring 2020: Construction is scheduled to be complete.


Financial Data for PIN 150915F, 150915G, 151801E, 151801F, 151801G
Funding Source Amount ($ in thousands)
2003 Gas Tax (Nickel Funding) $0
2005 Gas Tax (TPA) $0
Pre-Existing Funds (PEF) $12,843
CWA $0
Total $12,843


Jordan Longacre
WSDOT Communications