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I-5 - SR 18 to S. 288th Street Seismic Retrofit

Project map of the work area.
Click to view larger version of map.

Girders, columns, and cross-beams will be retrofitted to help strengthen I-5 bridges. Girders, columns, and cross-beams will be retrofitted to strenghten I-5 bridges.

Bridge columns at S. 288th St. to be retrofitted.
Columns under I-5 support the bridge deck as  it passes over S. 288th Street in Federal Way.

Bridge columns at S. 336th St. to be retrofitted.
Columns will be fitted with steel jackets to help strengthen them against earthquakes.


July 2015

  • This project was declared operationally complete on Feb. 2, 2015. Operationally complete means the majority of the work is finish and the roadway is open to traffic.
  • Learn more about WSDOT's seismic retrofit program.
  • Sign up to receive email updates about this project and other South King County topics.


Crews seismically retrofitted four bridged sections of Interstate 5 from State Route 18 to South 288th Street in Federal Way. This project helped reduce potential damage to I-5 bridges in the event of an earthquake by strengthening the columns and crossbeams that support the bridged sections. 

Work occurred under northbound and southbound I-5 at:

• SR 18/I-5 interchange in Federal Way.
• South 336th Street in Federal Way.
• Military Road South in Federal Way.
• South 288th Street in Federal Way.

What can drivers expect at the SR 18 interchange?

Drivers can expect minimal ramp and single lane closures in both directions of SR 18 approaching I-5.

What can drivers expect at South 336th Street, Military Road South, and South 288th Street?

• Drivers at South 336th Street and Military Road South can expect day and night work. Drivers will be flagged through the work zone at night.
• Drivers at South 288th street can expect work during the day and night. The right lane of South 288th Street will close from construction start to finish. Traffic will be shifted over, with one lane traveling in either direction.

Why is WSDOT seismically retrofitting four sections of I-5 from SR 18 to S. 288th Street?

I-5 was built more than 50 years ago to seismic standards that are now out of date. As a result, sections of I-5 in the Puget Sound area are vulnerable to earthquake damage. This project is part of our seismic retrofit program established in 1991 to help make bridges safer by bringing them up to current seismic standards.

As of March 2013, WSDOT has 913 bridges in the program, of which 284 have been completely retrofitted.

The End Result

WSDOT will make several types of improvements under the bridges to lessen the risk of earthquake damage and help keep drivers safe.

• Crews will install large steel sheets, called column jackets, around the existing columns that hold up the bridges. This will help prevent columns from crumbling during a quake.
• Crews will add supports to the crossbeams which hold up the bridges. The added supports are called bolsters, which create a wider base for the bridge girders to lie on.
• Finally, crews will add girder stops. Girder stops are similar to bolsters. They add strength to the bridges and prevent the girders from sliding around on the crossbeams.

Project Benefits

– Strengthening bridge columns, crossbeams, and girders will help keep drivers safer by reducing the risk of damage during an earthquake. Concrete columns are less likely to crumble and bridge girders are less likely to slide off trusses and beams.

What is the project timeline?

  • Nov. 25, 2013 - Project advertised for competitive bidding.
  • Dec. 26, 2013 - Project awarded to Ceccanti, Inc. 
  • Monday, March 24, 2014 - Construction began.
  • February 2, 2015 - This project was declared operationally complete. Operationally complete means the majority of the work is finish and the roadway is open to traffic.

Financial Information

Financial Data for PIN 100502N
Funding Source Amount ($ in thousands)
2003 Gas Tax (Nickel Funding) $0
2005 Gas Tax (TPA) $0
Pre-Existing Funds (PEF) $6,821
Total $6,821

Project signage will reflect the cost of construction engineering, project bid award and sales tax.

How can I get more information?
Mike Askarian
WSDOT Project Engineer
Phone: (206) 768-5861

Kris Olsen
WSDOT Communications
Phone: (206) 440-4704

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