I-5 - NB S 260th St to Duwamish River Br - Concrete Pavement Rehab and ADA

Project news

  • Travelers should plan ahead for lane reductions on the northbound I-5 Duwamish River Bridge the weekend of Feb. 23-24, weather-dependent.
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Why is WSDOT rehabilitating this section of northbound I-5?

This section of I-5 was built in 1965 and designed to last about 25 years. It has now lasted more than 51 years. It carries about 100,000 vehicles each day. Much of the roadway is worn out, and drivers often notice bumps where concrete panels are broken. Decades of heavy traffic has worn ruts into the roadway. In addition, worn out expansion joints must be replaced.

Project details
This two-year project presents numerous challenges as crews are:

  • Replacing about 440 broken concrete panels, mostly during nighttime lane closures. 
  • Repaving about 4 miles of all lanes with asphalt between SR 516 and South 178th Street. 
  • Grinding off ruts and bumps. 
  • Replacing eight expansion joints on the Interurban Avenue and Duwamish River bridges. 
  • Rehabilitating the Interurban Avenue and Duwamish River bridge decks.
  • Creating better sidewalk connections for people of all abilities at several intersections. 

Work progress
Contractor crews made substantial progress working on 12 weekends between June and November 2017 on northbound I-5:

  • Finished the crack and seat portion of the work on four miles between SR 516 and Southcenter.
  • Finished paving all lanes between SR 516 and Southcenter.
  • Replaced more than 300 broken concrete panels.
  • Replaced the four expansion joints at Interurban Avenue.
  • Replaced four expansion joints on the Duwamish River Bridge.
  • Repaved the both sides of the Interurban Avenue overpass and Duwamish River Bridge.

Needs & Benefits


  • Replacing broken concrete panels, repaving and grinding the interstate improves the driving surface and will extend the life of I-5. 
  • Replacing expansion joints on the Interurban Avenue and Duwamish River bridges ensures those structures will remain open and operational.


  • Improving the interstate surface eliminates potholes and will help prevent future potholes and cracks. Eliminating the wheel ruts improves traction and will create a smoother, safer ride for drivers. 
  • Replacing the expansion joints on the Interurban Avenue and Duwamish River bridges reduces the chances that an aging expansion joint could fail, which would create a hazard for drivers and cause an emergency closure on I-5.


  • Replacing broken concrete panels, repaving and replacing expansion joints during a scheduled project reduces the need for emergency repairs, which are more expensive than scheduled repairs and cause additional congestion, particularly during peak commute hours. 
  • Repaving a 4-mile section of the interstate with asphalt instead of concrete is less expensive and less disruptive than replacing all of the concrete panels.

The End Result

This preservation and improvement project will create safer and improved driving conditions for the tens of thousands of travelers who rely on the interstate daily. It also will extend the useful life of I-5 for decades to come. This project is part of a years-long effort to preserve I-5 through King County.


  • November 2016: Project was advertised for competitive bidding.
  • January 2017: Project was awarded to Gary Merlino Construction Co. Inc.
  • April 2017: Construction began.
  • Spring 2019: Construction is scheduled to be complete. 


Financial Data for PIN 100506G, 100506H
Funding Source Amount ($ in thousands)
2003 Gas Tax (Nickel Funding) $39,764
2005 Gas Tax (TPA) $0
Pre-Existing Funds (PEF) $102
CWA $0
Total $39,866


Nicole Daniels
WSDOT Communications