The hidden impact of extreme heat on infrastructure
The heatwaves are putting added strain on already struggling infrastructure systems in many parts of the US, and people don’t even realize it yet.
Infrastructure across the US is struggling with the climate crisis, with dramatic examples including torrential rains turning New York City subway entrances into waterfalls, record cold snaps shutting down the Texas power grid, and rising Pacific sea levels eroding coastal highways.
Extreme heat has left its own, more subtle mark on the built environment: roads, power lines, transportation systems, and hospitals have been affected, and for some infrastructure, researchers are only just beginning to understand the heat’s effects.
“Heat itself is kind of an invisible hazard,” says Sarah Meelow, an urban planner at Arizona State University. “You don’t see its effects as quickly as you would with a flood or a hurricane or a wildfire, but it’s there.”
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Heat-induced infrastructure problems can occur not only in places with extreme temperatures like Arizona, but also in traditionally cool places like the Pacific Northwest, where temperatures are rising faster than ever before. This is because local infrastructure was not designed to withstand a changing climate. It’s not the absolute temperature that matters, but how far off it is from what engineers predicted when they built the infrastructure.
For example, roads across the United States are made with several different asphalt mixes depending on the weather conditions. Regardless of the mix, if the asphalt is exposed to temperatures higher than it can withstand, it will soften. Heavy vehicles can then trample the asphalt like mud, leaving ruts. Overheated asphalt can also crack.
Much of the heat-induced chaos comes from brute physical realities, like the fact that most materials expand when heated. “You don’t have to be an engineer to know that materials will deform when exposed to temperature changes,” says Alessandro Lotta Loria, an architectural engineer at Northwestern University.
The Third Avenue Bridge in New York City was locked down due to high temperatures on July 8, 2024, and workers sprayed the bridge with water to cool it down.
Selcuk Akar/Anadolu via Getty Images
Overheated train tracks can twist and bridges can buckle or become unable to function as they should — like when a drawbridge in New York City got stuck open last month. Airlines struggle because thinner air makes it harder for planes to generate lift, requiring additional runways, and makes planes more likely to experience turbulence.
Some infrastructure suffers from compounding problems. Fully operational power lines can sag at high temperatures, posing a fire hazard if they touch trees or other obstructions. To mitigate the risks, grid managers reduce the amount of energy flowing through the wires. Coal-fired and nuclear plants rely on safety mechanisms that use water to cool their systems. But in hot weather, this water is already very warm and can’t absorb as much heat, forcing managers to slow energy production to keep the systems safe.
“The heat is actually making it harder for power plants to deliver the electricity they normally deliver,” says Christina Dahl, a climate scientist at the Union of Concerned Scientists. “The way power plants and grids work makes it harder for them to meet average loads during times of extreme heat.” At the same time, energy demand is soaring as people turn to power-hungry air conditioners to protect themselves from the heat.
Although hospitals are relatively physically protected, they can be overwhelmed during extreme heat: Hot weather brings more people to hospitals for problems such as heat stroke, asthma, and cardiovascular disease, and interpersonal violence also increases with temperature — all on top of the normal incidence of bone fractures and other emergencies.
As drinking water flows through extremely hot underground pipes, it can warm up to temperatures far above the maximum of 77 degrees Fahrenheit (25 degrees Celsius) recommended by the World Health Organization to limit opportunities for microorganisms to grow, says Kyrin Emrett First, an environmental engineer at George Mason University. Researchers are trying to understand what risks the heat poses to water infrastructure and whether it increases the leaching of metals, plastics, or both into tap water.
Lotta Loria’s research focuses on underground urban heat islands – masses of heat underground that are generated by waste heat and energy from buildings, underground infrastructure and other built structures. This heat makes subways so hot in summer. In addition, trains that enter the tunnels from above-ground tracks push hot air forward, further heating the system. Buildings and other infrastructure exposed to underground heat are prone to low-level damage that requires costly repairs.
Heat can cause problems in all kinds of infrastructure that researchers haven’t yet fully recognized, because they’re less noticeable than grounded planes or crowded emergency rooms. Heat generally accelerates wear and tear, which in turn increases repair costs. “When we have these heat waves in the summer, we tend to see breakdowns much more frequently than when temperatures are more moderate,” says Mikhail Chester, a civil engineer at Arizona State University. Administrators may have to take systems offline to avoid serious problems. “The mere threat of a breakdown is enough to disrupt service,” Chester says.
Even without the climate crisis, the country’s aging infrastructure is struggling under poor maintenance and high demand, says Janey Camp, a civil engineer at the University of Memphis. “We built them because we thought we needed wading pools, but what we really need are Olympic pools,” Camp says. “And we’re not investing in expanding wading pools.”
As the climate crisis unfolds and infrastructure continues to age, cities across the US need to invest in maintaining and upgrading the systems that underpin our daily lives. “This hidden infrastructure is the heartbeat of our communities,” says Dev Niyogi, an urban climatologist at the University of Texas at Austin. “You only realize how valuable it is when you can’t access it.”
