America's bridges are falling apart faster than expected

Roughly a third of the nation's 620,000 bridges — 36% — need major repair work or replacement, a new report finds.

Why it matters: Deferred maintenance, climate change and heavier-than-anticipated traffic are causing bridges to wear out earlier than expected, and engineers say not enough is being done to keep drivers safe.

Driving the news: More than 43,500 U.S. bridges are in poor enough condition to be deemed "structurally deficient," according to the report by the American Road & Transportation Builders Association (ARTBA).

• Those bridges are crossed 167.5 million times a day.
• Chunks of concrete fall from bridges with some regularity, and routine inspections often reveal problems that prompt authorities to shut down lanes of traffic or close off a bridge to heavy vehicles, to reduce the weight burden.
• A bridge collapse last week in Pittsburgh — on the same day President Biden visited the city to talk about infrastructure — highlighted the problem, but engineers say it's a bigger issue than many Americans may realize.

At the current rate, it would take 30 years to fix all of America's structurally deficient bridges.

• "There’s progress being made — it’s just at a very slow pace," says Alison Premo Black, senior vice president and chief economist at ARTBA.
• "It's just very disturbing that [accidents like Pittsburgh] can still happen despite all the steps being taken to keep the traveling public safe," Black tells Axios.

What's happening: Historic sums are about to be spent on bridge repair — more than $26.5 billion over five years — under Biden's infrastructure law, the Department of Transportation announced in January.

• Transportation Secretary Pete Buttigieg called it "the single largest dedicated bridge investment since the construction of the Interstate highway system."

The intrigue: Many bridges were built after World War II and meant to last 100 years. But they're falling apart ahead of schedule, due to combinations of extreme weather, the enormous growth of vehicle traffic, deferred maintenance and a lack of coordinated oversight.

• "You just have these cities which are growing to an unprecedented extent, and the infrastructure was never designed to handle the amount of traffic that these structures are expected to deal with every day," Kevan Stone, executive director of the National Association of County Engineers, said.

What's next: It's time to deploy new technology to the old-world practices of bridge inspection and maintenance, says Matti Kuivalainen the CEO of Dywidag, one of the world's leading bridge engineering firms.

• That means the widespread installation of sensors that can help predict problems — which is happening in Europe but not the U.S., Kuivalainen said.
• "We need to monitor the actual behavior of a bridge versus how it's supposed to behave," Kuivalainen tells Axios. "That, together with physical inspections, will help DOT to identify bridges at risk and prioritize repairs and replacement projects."

The bottom line: "Absolutely, there is regulation needed" to require the sophisticated monitoring programs that are absent from U.S. bridges today, Kuivalainen says.

Editor's Note: This story was originally published on Feb. 4.