Study: 1 in 4 U.S. bridges deficient or obsolete

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Twenty-six percent of U.S. bridges are structurally deficient or functionally obsolete, according to a national nonprofit that advocates road construction. TRIP, The Road Information Program, analyzed federal and state data to come up with its numbers.

In engineering circles, a structurally deficient bridge is one in serious need of repair, while a functionally obsolete bridge is one with a design or capacity no longer adequate for traffic demands. The percentage of substandard bridges nationwide is about evenly divided between the deficient and the obsolete at 13 percent each, TRIP says.

Jurisdictions earning bad grades from TRIP for their high percentage of deficient or obsolete bridges include the Michigan cities of Detroit (41 percent) and Lansing (33 percent) and the states of New Hampshire (32 percent) and Mississippi (20 percent).

Thirty-six percent of Maine’s bridges are structurally deficient or functionally obsolete, TRIP says. Most bridges are designed to last only 50 to 80 years, and half of Maine’s bridges are at least 50 years old, TRIP says. Of the 10 most heavily traveled Maine bridges, the most structurally deficient is the two-lane U.S. 1 bridge over the Piscataqua River in York County, built in 1923, TRIP says.

The group also says 35 percent of major roads in the United States are in poor or mediocre condition. Between 1990 and 2004, TRIP points out, the U.S. population grew 13 percent, and vehicle travel on the nation’s highways increased 38 percent. For more information, go to www.tripnet.org.