The collapse of the Francis Scott Key Bridge in Baltimore is the latest example of a challenge to U.S. infrastructure amid a lack of funds and motivation to maintain aging bridges, experts say.
The Baltimore bridge “is an old and reliable piece of infrastructure, that under almost any reasonable circumstances would be standing in another 20 or 30 years,” says Joseph L. Schofer, professor emeritus of civil and environmental engineering at Northwestern University’s McCormick School of Engineering. “If you come along and pull out the primary support, there’s no way to save the bridge.”
Though he has no reason to believe negligence was involved in the Baltimore collapse, Schofer says some infrastructure catastrophes are. He points to the Fern Hollow Bridge failure in Pittsburgh as an example: The National Transportation Safety Board concluded reports and recommendations to fix corroded steel supports went ignored, ultimately leading to the collapse of the 447-foot-long bridge, which dropped a bus and four cars to the park below.
It’s a disturbing trend as train derailments, highway and bridge collapses, and dam failures are being seen across the U.S, experts say. But which areas are civil engineers most concerned could cause imminent catastrophe, and what can we do about it?
Physical collapse is happening now
Federal funding will rebuild the Francis Scott Key Bridge, which more than 30,000 cars use daily.
“In terms of where you go from here, you’ve got a bridge that’s failed, and probably more likely, you want to rebuild it. So what are your options?” Schofer says.
“Going forward, you’ve got some really interesting design options that could either make the likelihood of this kind of event very small or eliminated entirely, and I think probably that’s what they’ll do with a new design.”
But many other key structures across the country aren’t getting the same attention.
“There are cautionary tales all over,” says Maria Lehman, president of the American Society of Civil Engineeers (ASCE) and vice chair of the Biden administration’s National Infrastructure Advisory Council. “Every county in the country has a list of bridges that, if they had money, they would replace tomorrow.”
The 617,000 bridges in the U.S. include not just those spanning mighty rivers but also every highway overpass and minor link across a stream—and close to one tenth of them are significantly compromised. “If you have to think in terms of catastrophe, we’re already there,” says Amlan Mukherjee, the director of sustainability focusing on infrastructure at WAP Sustainability Consulting.
In 2007, the collapse of an I-35W bridge in Minnesota killed 13 people and injured 145. More recently, a six-lane bridge over the Mississippi was closed for three months in 2021, disrupting interstate travel and shipping because an inspector missed a significant crack. Americans drive 178 million trips on structurally deficient bridges each day, according to the 2021 report from the ASCE.
Yet the U.S. spends only 1.5 to 2.5 percent of its GDP on infrastructure, proportionately less than half of what the European Union spends, Lehman says. This long-term lack of funding has run out the clock on many solutions. Many U.S. bridges were built to last 30 to 50 years, but nearly half are at least half a century old. The average age of U.S. levees is also 50; dams average 57.
The future of U.S. infrastructure
Mukherjee is optimistic about the use of new technology to solve some of the country’s infrastructure issues, though adoption has been slow. Drones can provide human inspectors with up-close views of areas they can’t reach themselves and reduce chance of human error; a drone on an unrelated project captured footage of the Mississippi bridge crack two years before its discovery.
Bilal Ayyub, a professor of civil and environmental engineering at the University of Maryland, College Park, has also worked with North American freight railroads to find weak links using computer modeling. This can comb through thousands of stations to “identify exactly which point if it fails will have the biggest impact,” he says.
One piece of good news, experts say: in 2021, Congress passed the Bipartisan Infrastructure Law, which provides $1.2 trillion over five years for the ailing systems that help American society run—the largest federal investment in U.S. history.
“Every president for the last eight presidents said we should spend a lot of money—like a trillion dollars—on infrastructure, and none of them delivered,” Lehman says.
Unless it is renewed regularly, though, this funding will barely stop the bleeding. It’s time for the U.S. to begin maintaining the systems that make so much of American life possible while they’re still in working condition, Lehman says.
“If you have a leak in your roof, you go up there, find it, replace the shingles, put on a little tar,” she says. “If you let it go, it’s not going to be a little fix: It’s going to be a replacement.”
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