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Transportation Final 10-15-09 -   2.2 - State Bridge Conditions

 
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Transportation Final 10-15-09
1. Safety
2. Preservation
3. Mobility
4. Environment
5. Stewardship
Current Conditions
6. Economic Recovery
  
 
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 Action Plan

Expand/Collapse ForumDate‎(4)
Clean and paint steel bridges to preserve structural integrity.Use SHIFT+ENTER to open the menu (new window).
WSDOT Bridge Office6/30/2011In Progress9/30/2009
Replace bridges as programmed.Use SHIFT+ENTER to open the menu (new window).
WSDOT Bridge OfficeIn Progress9/30/2009
Repair and overlay bridges as fundedUse SHIFT+ENTER to open the menu (new window).
WSDOT Bridge Office6/30/2011In Progress9/30/2009
Retrofit bridges as programmedUse SHIFT+ENTER to open the menu (new window).
WSDOT Bridge OfficeIn Progress9/30/2009

 Extended Analysis

Safety Issues

Bridge Painting:

  • Protective paint coatings on steel bridge elements are essential to prevent corrosion that reduce the steel’s capacity to carry truck loads.
  • Paint condition on many bridges is now too old for an overcoat; instead these bridges will require full paint removal down to bare metal and then repainting at a cost typically 20-30% of a bridge’s replacement cost.
  • There are 99 WSDOT steel bridges that are either due or past due for painting. The cost to repaint these bridges, plus the Astoria Bridge, is estimated to be $388 million. The funding needed to address these bridges over the next 10 years will be $78 million per biennia. WSDOT repainted four bridges between 2005 and 2009 compared to 37 bridges between 2000 and 2004.

Seismic retrofit:

  • Retrofit Designs are based on designing for a 1,000 year earthquake due to criteria adopted in January 2008 by FHWA and AASHTO, which has caused project costs to escalate from initial estimates. WSDOT has collaborated with Federal, State and Local Agencies to determine how the remaining seismic retrofits should be prioritized.
  • The conclusion was to focus on the bridges on I-5 from the McCord Air Force Base to the I-5 and I-90 interchange in Seattle. Retrofitting these bridges along I-5 will provide a systematic plan that will begin to provide an earthquake resilient route that could be used to speed a recovery following a major seismic event.

Scour mitigation:

  • “Scour” is the eroding of stream bed material from under bridge foundations. Scour generally happens when a river experiences high water flows.
  • Nationally, as in Washington, more bridges have collapsed from the scour of bridge foundations than from any other cause.
  • WSDOT develops a list of bridges requiring scour mitigation each biennium, and is currently prioritizing the top 50 scour critical bridges.
  • While these 50 should be retrofitted in the next six years, WSDOT will only be able to retrofit six bridges per biennium, due to the costs and timelines associated with developing solutions to the scour problems that are not only protective of the bridge structure but that also protect or mitigate for impacts to fish and the environment.