November 2011
- Construction began in July 2010 and will continue through winter 2011.
If you drive on State Route 520 through Bellevue, one of the things you may not notice is that a good portion of the ride is on bridges that cross a maze of surface streets.
The Washington State Department of Transportation will retrofit 8 of the bridges between Interstate 405 and 148th Avenue NE, and one bridge on I-90 at Richards Road, to better withstand earthquakes.
Why is WSDOT
retrofitting bridges on SR 520 and I-90?
The Puget Sound region is prone to earthquakes. Most of the SR 520 bridges were built in the 1960s and early 1970s when engineers didn’t know as much about how earthquakes affect these structures.
Lessons learned after the severe California earthquakes of the 1970s and 1980s led to a change in how engineers design bridges to withstand earthquakes. But most of Washington’s 3000 vehicular bridges were built before these new design standards were incorporated.
WSDOT developed its Seismic Retrofit Program in 1990 in response to the new design standards and to gain a greater understanding of the earthquake risk in the Puget Sound area. In this program WSDOT is strengthening more than 900 bridges and structures across the state.
The End Result
When work is complete in 2011 the following bridges will be better equipped to withstand severe earthquakes.
• SR 520 bridges (2) over 116th Avenue NE (built in 1966)
• SR 520 bridges (1) over BNSF railroad (built in 1966 and 1969)
• SR 520 bridges (1) over Northup Way (built in 1971)
• SR 520 bridges (1) over the NE 124th Street on-ramps (built in 1971)
• SR 520 bridges (2) over 130th Avenue NE (built in 1970)
• SR 520 bridge (1) over NE 24th Street (built in 1970)
• I-90 at Richards Road
Crews will strengthen the bridges by:
• Installing steel jackets over the vertical columns on eight of the nine bridges
• Installing reinforced concrete bolsters on the horizontal crossbeams of seven of the 8 bridges.
Project Benefits
- Safety: Strengthening bridge columns and crossbeams will reduce the risk of catastrophic failure during an earthquake.
- Environment: Crews will filter storm water runoff during construction.
What is the project timeline?
- May 5, 2010: Contract awarded to Atkinson Construction.
- Summer 2010: Construction begins
- Fall 2011: Expected completion
Financial Information
This project is funded through the following sources:
2005 Gas Tax (Partnership Funding) - $5,353,000
Total Funding Available From All Sources - $5,353,000
How can I get more information?
Contact:
John Chi
WSDOT Project Engineer
ChiJ@wsdot.wa.gov
425-489-5402
Mike Murphy
WSDOT Communications
MurphyM@wsdot.wa.gov
206-440-4699
back to top