Approximately one in four of the country’s major, heavily traveled bridges is deficient and in need of repair or replacement -- and heavy truck travel is partly to blame, according to a national nonprofit transportation research group based in Washington, D.C.

The study, released Tuesday by The Road Information Program, found that 14 percent of the country’s bridges are structurally deficient, showing significant deterioration to decks and other major components. In addition, 14 percent are functionally obsolete. These bridges no longer meet modern design standards for safety features such as lane widths or alignment with connecting roads or no longer are adequate for the volume of traffic being carried.
According to the report, “Showing Their Age: The Nation’s Bridges at 40,” nearly half of the nation’s bridges – 48 percent – were built from 1950 to 1980, with the 1960s being the greatest bridge-building era, when 19 percent of the bridges open to traffic were built, according to TRIP.
Oklahoma led the nation with the largest percentage of bridges that have structural defects: 33 percent.
Several heavily traveled bridges in larger cities, especially older cities, have significant deficiencies. These cities include New York, Boston, Detroit and St. Louis.
TRIP officials say that while progress has been made, growth in car and truck travel combined with a possible cut in federal and state highway funding may reverse recent gains.
According to TRIP, a U.S Department of Transportation report to Congress concluded that investment in the nation’s bridges should be increased by 44 percent, from $8.1 billion annually to $11.7 billion, an increase of $3.6 billion a year.
Vehicle travel nationally increased by 28 percent between 1990 and 2000. Travel by large commercial trucks increased by 40 percent between 1990 and 2000, significantly increasing the load being carried by bridges.
“Vehicle travel by all vehicles is expected to increase by another 50 percent by the year 2020 and travel by large commercial trucks is expected to increase by 90 percent by the year 2020, according to FHWA forecasts,” said Wilkins, accelerating bridge deterioration.
For more information, including a complete list of the 100 worst bridges, visit www.tripnet.org.