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October 29, 2009

26% of US Bridges are Structurally Deficient or Functionally Obsolete

The recent problems with the San Francisco Bay Bridge highlights the need to address the larger problems with the bridges in the United States

Abolhassan Astaneh-Asl, a structural engineering professor at the University of California, Berkeley, says he's concerned that authorities took a "Band-Aid" approach in September [to fixing the Bay Bridge]. "It failed," he said. He's worried about what he calls "fracture-critical" bridges: roughly 460 bridges across the country that are in dire need of repairs.



9 page pdf with the 2009 US Bridge Infrastructure report card

26%, or one in four, of the nation’s bridges are either structurally deficient or functionally obsolete. While some progress has been made in recent years to reduce the number of deficient and obsolete bridges in rural areas, the number in urban areas is rising. A $17 billion annual investment is needed to substantially improve current bridge conditions. Currently, only $10.5 billion is spent annually on the construction and maintenance of bridges.




The complete list of 2009 American Society of Civil Engineers Infrastructure report cards



Accelerated Bridge Construction

The Utah Department of Transportation (UDOT) has used some form of the accelerated bridge construction (ABC) method on 19 projects that have included 77 bridges. The majority of these projects entailed the use of precast decks cast off-site and lifted into place over a short period of time—often overnight. The benefits of the ABC method include not only reduced road closure time and a compressed schedule, but enhanced quality and increased safety for drivers and construction workers as well. The concept of fabricating entire bridge spans off-site and moving them into place with self-propelled modular transports (SPMTs) was used in four projects that replaced a total of 13 bridges. The use of off-site fabrication and SPMTs usually allows for the replacement of bridge spans over a weekend.



Report Card Conclusion
While some progress has been made recently in improving the condition of the nation’s rural bridges, there has been an increase in the number of deficient
urban bridges. At the same time, truck traffic over the nation’s bridges is on the rise—a matter of great concern as trucks carry significantly heavier loads than automobiles and exact more wear and tear on bridges. The investment gap is accelerating and the failure to invest adequately in the nation’s bridges will lead to increased congestion and delays for motorists, wasted fuel, the further deterioration of bridge conditions, and increased safety concerns. Once Congress works to address these problems in the 2009 authorization of the Surface Transportation Program, it should establish a goal that less than 15% of the nation’s bridges be classified as structurally deficient or functionally obsolete by 2013 and should provide the funding needed to accomplish that.


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