The latest Federal Highway Administration National Bridge Inventory (NBI) data show a total of 25 percent of the nation’s bridges 20 ft. or longer are either structurally deficient or functionally obsolete. Eleven percent of the 600,000-plus NBI crossings are structurally deficient, indicating significant deterioration of the deck, supports or other major components. Structurally deficient crossings may be posted for lower weight limits or closed if their condition warrants.
An additional 14 percent of NBI structures are functionally obsolete, indicating they no longer meet current highway design standards, often due to narrow lanes, inadequate clearances or poor alignment with approaching roadway. Structurally deficient and functionally obsolete bridges are safe for travel and monitored regularly.
Pennsylvania leads the nation in the share of structurally deficient bridges with 24 percent, followed by Oklahoma (23 percent), Iowa (21 percent), Rhode Island (21 percent) and South Dakota (21 percent). The U.S. currently spends approximately $14 billion annually in maintaining its more than 600,000 bridges. But based on the findings of a 2010 U.S. Department of Transportation report to Congress, the nation should be spending approximately 60 percent more, or $22 billion, to achieve significant improvements in NBI structures.
“Improving bridge conditions—and the overall condition of the nation’s surface transportation infrastructure—will require a significant increase in transportation investment at federal and state levels,” says Will Wilkins, executive director of The Road Information Program, Washington, D.C. With the current federal surface transportation program (MAP-21) expiring Sept. 30, 2014, he adds, Congress has the opportunity with successor legislation to increase bridge investments.