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Budget Information

I-5 - SB S 320th St to Duwamish River Bridge - Concrete Pavement Rehab

The southbound Interstate 5 concrete pavement rehab project is located along 12.86 miles of freeway from Duwamish River Bridge in Tukwila to South 320th Street in Federal Way. View larger map

A small photo showing the condition of I-5, along with asphalt patches, between Federal Way and the Duwamish River Bridge.
There are more than 200 cracked and patched concrete panels on southbound I-5 from Tukwila to Federal Way.


November 2017

  • Work was completed July 20, 2017.
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Contractor crews have rehabilitated nearly 13 miles of southbound Interstate 5 between the Duwamish River Bridge in Tukwila and South 320th Street in Federal Way. Crews have:

  • Replaced 238 broken concrete panels and grind out cracks and bumps.
  • Repaved 2.7 miles of concrete roadway across five lanes with new asphalt.
  • Repaved five on-and off-ramps.
  • Replaced aging and worn expansion joints on the Duwamish River Bridge.

Why is WSDOT rehabilitating this section of southbound I-5?
These lanes of the interstate carry approximately 200,000 vehicles each day. The interstate was built in 1965. The concrete roadway was only intended to last 25 years, but has now doubled its lifespan.

In addition to its age, the increasing number of cars and heavy trucks on the road, along with freeze/thaw cycles, have contributed to the deterioration of the highway. Drivers can notice this in the tell-tale "thump, thump, thump" of their vehicle's wheels. That's the sign of a broken concrete panel that is rocking back and forth, and beyond its lifespan.

Other problems in the southbound lanes that were addressed include potholes, wheel ruts and worn expansion joints.  

Concrete panel replacement
Crews have replaced 238 concrete panels throughout the length of the project. These panels were cracked beyond repair.

Throughout the project, crews have repaved multiple lanes in various locations. 
Crack and seat
Crews have resurfaced a 2.7-mile section of southbound I-5 between South 188th Street and South 219th Street. The concrete was replaced with asphalt using a process called "crack and seat."

This process allows crews pave over existing concrete roadway. To do this, crews use heavy machinery to break up (crack) the concrete panels that make up the roadway. Next, more heavy machinery is used to compact (seat) the broken concrete into the existing roadbed. Finally, an 8-inch thick layer of asphalt is then placed to create a new driving surface.

Roadway grinding
Roadway grinding is one of the most cost-efficient and effective ways to improve the driving surface of aging concrete.

Grinding removes a very thin layer of the concrete to reveal a new surface. This new surface improves traction for drivers and removes wheel ruts where water can pool.

Grinding work was performed throughout the length of the project in areas that were not repaved. 
Expansion joint replacement
Four deteriorating 20-year-old expansion joints on the southbound Duwamish River Bridge were replaced.

Expansion joints are critical to the safe operation of bridges. They allow a bridge to bend and flex as the concrete on the bridge expands and contracts with changing traffic and freeze/thaw cycles. An expansion joint that fails can pop up into traffic.

Groundwater repair
Crews repaired an area just north of the I-405/SR 518 interchange where groundwater was not draining properly.

The End Result
This preservation and improvement work will extend the useful life of the interstate for years to come, creating safer and improved driving conditions for the thousands of travelers who use it each day.

Project Benefits

  • Preservation
    • Replacing broken concrete panels, repaving, and grinding the roadway improves the driving surface and extends the life of I-5.
    • Replacing bridge expansion joints on the Duwamish River Bridge ensures the bridge will remain open and operational.
  • Safety
    • Improving the highway surface eliminates and helps prevent future potholes, cracks and wheel ruts, making for a smoother, safer ride for drivers.
    • Replacing the Duwamish River Bridge expansion joints creates safer driving conditions by reducing the chances that an aging expansion joint could become dislodged or fail, creating a hazard to drivers and forcing an emergency closure of the bridge.
  • Economic
    • Replacing broken concrete panels, repaving and replacing bridge expansion joints reduces the need for emergency repairs, which are costly to taxpayers and can cause additional congestion during peak commute hours. In addition, removing all the concrete at between South 219th and South 188th Street and placing new asphalt is less expensive than placing all new concrete.

What is the project timeline?

  • October 2015 - The project was advertised for competitive bidding.
  • December 2015 - Project was awarded to Midmountain Contractors, Inc.
  • March 2016 - Construction started.
  • July 2017 - Work was completed.

Financial Information

Financial Data for PIN 100504B
Funding Source Amount ($ in thousands)
2003 Gas Tax (Nickel Funding) $0
2005 Gas Tax (TPA) $0
Pre-Existing Funds (PEF) $27,275
CWA $0
Total $27,275

How can I get more information?
Tom Pearce
WSDOT Communications
Phone: 206-440-4696

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