Associated Press
Nearly one-third of Missouri’s bridges are either structurally deficient or functionally obsolete, according to an inventory of the nation’s bridges that takes on new relevance as Missouri and other states move to ensure their bridges are safe after the collapse of a span in Minneapolis.
Of Missouri’s 24,024 bridges, nearly 20 percent, or 4,595, were structurally deficient, meaning they are deteriorating, according to a 2006 Federal Highway Administration report.
Only three states have more bridges in poor condition – Oklahoma (6,299), Pennsylvania (5,582) and Iowa (5,152).
An additional 3,141, or 13.1 percent, are functionally obsolete, meaning they’re not constructed to modern standards for loading and traffic volume.
The report says 12.4 percent of the nation’s bridges are structurally deficient and 13.4 percent are functionally obsolete.
“All the states face this problem. It’s not particular to Missouri,” said University of Missouri-Columbia civil engineer Glenn Washer. “There’s a huge national need for additional funding to bring bridges to satisfactory condition. There’s only so much funding available.”
One possible solution is bringing the state’s 800 worst bridges back to satisfactory condition through replacement and repair by an outside contractor, who would maintain them for 25 years, Washer said. The work is out to bid. “The state will decide if it can afford to execute it,” he said.
The initiative stalled in the last legislative session over a technicality relating to bonding requirements. A spokeswoman for Gov. Matt Blunt said he has been considering a possible legislative fix in a special session, but no decision has been made.
Blunt on Thursday asked the Missouri Department of Transportation to look into bridge safety. It responded by immediately beginning inspections of the 11 state highway bridges that have a similar design as the one that collapsed Wednesday in Minnesota. That does not include bridges under the watch of cities and counties.
St. Louis County Executive Charlie Dooley on Thursday ordered a nearly 90-year-old span closed as a safety precaution. St. Louis Mayor Francis Slay ordered inspections of several bridges, including the historic Eads Bridge, which opened in 1874.
“We are beginning a very close-up examination of the bridges today,” MoDOT spokesman Jeff Briggs said. “We’re looking for possible problems and we will fix them.
“What we don’t know is what caused the bridge in Minnesota to collapse. Once we do, that will give us more guidance what to look for.”
Of the 10,240 bridges in Missouri’s state highway system, one has been identified as a deck arch truss bridge, the type that collapsed in Minnesota, Briggs said.
The Hurricane Deck Bridge carries traffic on Route 5 that spans the Osage Arm at Lake of the Ozarks, and was built in the 1930s. A spokeswoman for Blunt said transportation officials have no reason to believe it is unsafe, but will inspect the bridge to confirm its safety. The inspection is scheduled for Friday.
Missouri has 10 more that are deck truss bridges with no arch at the bottom, Briggs said.
Regulations call for every bridge in the nation to be inspected every two years. Inspectors rate from 1 (deficient) to 10 (perfect) the bridge deck, superstructure and substructure, said John Myers, associate professor of civil, architectural and environmental engineering at the University of Missouri-Rolla.
Any bridge assigned 4 or lower is deemed structurally deficient.
“It doesn’t necessarily mean the bridge is going to collapse,” Myers said. “They’re overdesigned, designed for 40 or 50 percent more load than structures should see.”
He said it is reassuring that the bridges are designed with a safety factor in mind and have rigorous inspection and maintenance program. “The ones with problems are well known, and they are prioritized,” he said. “I wouldn’t be alarmed.”
It wasn’t until 1970 that design codes were improved to accommodate earthquakes. Myers recommends retrofitting anything built before 1970.
Most bridges are built to serve 25 to 40 years.