SR 509 & SR 518 - S 192nd St to Normandy Pk & SR 509 to SR 99 Paving & ADA & Deck & Seismic - Complete August 2020


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 was cracked and in need of repair. 

WSDOT contractor crews repaved both directions of SR 509/1st Avenue South in Normandy Park and SR 518 in SeaTac. They also upgraded sidewalk ramps on SR 509 and seismically retrofited 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.
  • Summer 2020: Construction complete.


Final cost for this project is still being assessed. Once compiled, the information will be posted here.

  • Pre-Existing Funds (PEF) $12,843


Jordan Longacre
WSDOT Communications