The next time you drive over a bridge in Bonneville County, you might want to cross your fingers.
An analysis of the recently-released 2014 U.S. Department of Transportation National Bridge Inventory database shows there are more than 61,000 structurally deficient bridges in need of significant repair all across America. Idaho is home to 406 of them.
The analysis, conducted by American Road & Transportation Builders Association Chief Economist Dr. Alison Premo Black, shows cars, trucks and school buses cross Idaho's 406 structurally compromised bridges 533,126 times every day.
Not surprisingly, the most heavily traveled bridges tend to be on the Interstate Highway System, which carries the bulk of truck traffic and passenger vehicles.
In Idaho Falls, the northbound and southbound lanes of I-15 at Broadway and John’s Hole, all built in 1962, have been classified as functionally obsolete. Another heavily traveled bridge past its prime is the U.S. 20 overpass at Lewisville Highway. But the most heavily traveled is SM 7406 on 17th Street between South Boulevard and Calkins Avenue, over the Butte Arm Canal.
The bridge problem could get a whole lot worse soon, Black said. The federal Highway Trust Fund, the source of 52 percent of highway and bridge capital investments made annually by state governments, has suffered five revenue shortfalls between 2008 and 2014. Over that period, it has been bailed out with nearly $65 billion in revenues from the General Fund just to preserve existing investment levels. Without action from Congress, the latest extension expires on May 31. Nearly a dozen states so far have canceled or delayed road and bridge projects because of the continued uncertainty over the trust fund situation. ARTBA expects that number to increase as the deadline nears.
"State and local governments are doing the best they can to address these significant challenges, given limited resources," Black said. Bridge investments have been growing in recent years, but it has come at the expense of highway and pavement spending, which has dropped over 20 percent in the last five years.
"Without additional investment from all levels of government, our infrastructure spending will be a zero-sum game," she said, noting that there is a current backlog of over $115 billion in bridge work and $755 billion in highway projects. “Many of the most heavily traveled bridges are nearly 50 years old. Elected officials can't just sprinkle fairy dust on America's bridge problem and wish it away," Black said. "It will take committed investment by legislators at all levels of government."
Bridge decks and support structures are regularly inspected by the state transportation departments for deterioration and are rated on a scale of zero to nine—nine being "excellent" condition. A bridge is classified as structurally deficient and in need of repair if its overall rating is four or below.
While these bridges may not be imminently unsafe, ARTBA believes that signs should be posted so the public understands they have structural deficiencies that need repair.
The ARTBA analysis of the bridge data supplied by the states to the Transportation Department also found:
• Idaho ranks 35th place nationally in the number of structurally deficient bridges— 406.
• Idaho ranks 24th place in the percentage of its bridges that are classified as structurally deficient — 9 percent.
State specific bridge information from the analysis—including rankings and location lists of the 250 most heavily travelled structurally deficient bridges in the nation and top five most heavily travelled in each state—is available at www.artba.org/bridges.