Extreme heat broke a New York City bridge. Expect more infrastructure mishaps like this

When the temperature in New York City hit 95 degrees Fahrenheit earlier this week, it marked the hottest day of the year in the city so far. And that heat had an unexpected side effect: It caused the steel on the Third Avenue Bridge in the Bronx to swell, forcing the bridge to remain stuck in its open position and impeding road traffic during rush hour. It’s just one more way that extreme heat is affecting our daily lives, and another example of the impacts of climate change on infrastructure.

That bridge, which connects Manhattan to the Bronx, sometimes opens in order to let ships sailing along the Harlem River through. After it got stuck in that position, officials had to spray the bridge with water in an attempt to cool it down. The bridge got stuck around 4 p.m. and did not reopen to traffic until around 6:30 p.m.

Third Avenue Bridge Stuck 🌉📍#NYC The 3rd Ave Bridge stuck is stuck in the "open" position due to overheating machinery. FDNY Marine Units are en route to assist in cooling down the machinery to expedite the closure of the Third Avenue Bridge. Avoid the area and expect traffic… pic.twitter.com/zlEHGSC0eE— Citizen NYC (@CitizenAppNYC) July 8, 2024

Third Avenue Bridge Stuck 🌉📍#NYC The 3rd Ave Bridge stuck is stuck in the "open" position due to overheating machinery. FDNY Marine Units are en route to assist in cooling down the machinery to expedite the closure of the Third Avenue Bridge. Avoid the area and expect traffic… pic.twitter.com/zlEHGSC0eE

That steel expands during high temperatures isn’t surprising information. Engineers take this into consideration when building bridges and other infrastructure. Expansion joints accommodate the possibility of a bridge’s length changing due to temperature—longer from heat and shorter when contracting in the cold—says Masoud Ghandehari, a civil and urban engineering professor at New York University.

But temperatures are getting hotter and hotter, and human-caused climate change is making extreme heat and heat waves more frequent and intense. That reality may conflict with building standards that have been in place for decades. “Design guidelines tell you how much [movement] you should expect,” Ghandehari says. “And that design guideline is now going to have to change because of that extreme heat that we are experiencing.”

Extreme heat and infrastructure

It’s not only bridges: Heat also affects rails, which have steel tracks that can, during extreme scenarios, become 50 degrees hotter than the ambient air temperature. Extreme heat can make rail tracks buckle—called “sun kinks“—and also pull apart, making derailments more likely. Switch and control systems also face performance issues, and when temperatures are high, trains are forced to travel at slower speeds.

Roads aren’t spared either. In the sunlight on a hot day, asphalt can reach temperatures as high as 180 degrees. When asphalt gets that hot, it softens and can warp. “You drive over that, it results in extreme damage—big dips, trenches—because the asphalt is soft and deforms,” Ghandehari says. “And it doesn’t come back.”

There’s also the issue of wires, whether for train travel or power lines. Wires are designed for heat, because the electricity that travels through them is hot; when they get hot, they sag. But add a heat wave with extreme ambient air temperatures on top, and they sag even further. That’s another reason trains often have to travel more slowly—because the overhead wires are drooping.

“That additional sagging can be problematic from a point of view of adjacent trees and so on,” Ghandehari adds, “particularly when you add wind to it.” (Power lines are also most vulnerable to wind, he notes, which can often start wildfires.)

Heat also affects how rescue helicopters and even regular airplanes can take off. And then, of course, there are a whole host of health effects from heat, which scientists are still learning about. As heat waves become more common and more extreme, we’ll likely see even more impacts, on everything from cars to computers.

U.S. infrastructure is already in trouble—and climate change isn’t helping

Across the country, infrastructure of all kinds is aging—and failing. More than 42,000 U.S highway bridges are in “poor” condition, as are 43% of public roadways. Of the country’s more than 617,000 total bridges, 42% are at least 50 years old, and the backlog of bridge repair needs is $125 billion, according to the latest infrastructure report card from the American Society of Civil Engineers, for which the U.S. received a C-.

“We have just not spent enough money maintaining the aging infrastructure,” Ghandehari says. “Now, above and beyond the things getting old, we have to be concerned with the climate impact.”

The 2021 Bipartisan Infrastructure Bill is paying for the modernization of some long-neglected infrastructure. But climate change’s impacts will keep growing. And it’s not only heat: It’s also flooding, wildfires, wind, and all the other extreme weather that can be worsened by climate change and higher levels of greenhouse gas emissions.

The temperature tolerances that our infrastructure has been designed for may have been fine in the past, but our climate isn’t the same as it was when those bridges, roads, or other structures were built. 2023 marked the hottest year on record, and 2024 is shaping up to be even hotter. June 2024 was the planet’s warmest ever June, and also the 13th straight record-hot month.

When it comes to adapting to more intense summers, cities can look to places that have long had higher temperatures, says Clint Andrews, director of the Center for Urban Policy Research at Rutgers University. “Cities all over the world that lie closer to the equator than [New York] build infrastructure to a more heat-resistant standard,” he says. “We have to adapt ours in that direction, over time.”

Though the New York City bridge that got stuck because of the heat was ultimately functioning within hours, these sorts of climate change disruptions can have significant impacts—on traffic, which already costs the U.S economy more than $120 billion annually, or on train delays, which also cost commuters millions. “The collateral damage is high,” Ghandehari says. And of course, there’s the price of repairs. Already, climate change is costing the U.S. $150 billion a year in direct impacts like infrastructure damage, along with things like worker injuries and agricultural losses.