Dozens of states across the eastern U.S are experiencing dangerous levels of heat and humidity due to a heat dome. According to the National Weather Service, nearly 150 million people are affected.
Roads in multiple states have been buckling because of the extreme heat. The Wisconsin Department of Transportation reported more than 50 pavement buckles across Wisconsin. In Missouri, a car launched into the air after driving over a large bump in a buckled road. The Delaware Department of Transportation said it is repairing seven roads that have buckled in recent days.
“This is not very common, because if you’ve designed and built the road correctly, this shouldn’t happen. But it does happen once in a while,” said Amit Bhasin, director of the Center for Transportation Research at The University of Texas at Austin.
Bhasin explains there are two main types of roads: asphalt and concrete. The vast majority of roads are made of asphalt, which can soften and start rutting in extreme heat due to its flexibility. But the majority of the road buckling incidents reported in the news are on concrete roads.
How road buckling happens
When solid materials, like concrete, are heated, they expand. As Bhasin explains, concrete roads tend to expand under high temperatures.
Roads and materials are designed to handle temperature fluctuations, with the help of concrete joints — lines in between panels of concrete that allow for expansion in hot weather and contraction in cold weather. The joints open and close with these temperature changes.
“If your concrete is not designed to handle a certain temperature or… suddenly you have this extraordinary heat wave and it expands more than what the joint allows it to, then it’s got no place to go,” said Bhasin. “Then what it’s going to do is start pushing against the concrete panel from the other side of the joint and start moving into each other and cause breaking.”
And this problem isn’t likely to disappear. Scientists know that human-caused climate change is making heat waves more intense. In fact, heat waves are lasting longer and peaking at higher temperatures than in the past.
Every state designs its roads slightly differently depending on the typical weather of the state. And states not used to seeing extreme heat may have fewer roads prepared for it.
“If I were in Texas and I was seeing 110-degree temperatures and my roads are designed to handle that, it would be perfectly fine.”
Safety tips
Bhasin says that we can accept that there’s going to be a little bit of failure on our roads, because it’s not as concerning as damage to a building.
“It’s not like a building where… if a building starts to crack a little bit, you’re not going to feel safe,” he said.
But if there is too much cracking on the roads, Bhasin said, let your local agency know, because early intervention and repair are important.
Bhasin also noted that buckling on concrete roads usually happens gradually, and drivers should be cautious if they notice chipping or pieces of concrete falling loose, because they could cause debris to hit windshields.
Olivia Hampton edited the radio version of the story. Majd Al-Waheidi edited the digital version of the story.
Transcript:
A MARTÍNEZ, HOST:
It’s very hot and humid in dozens of states. The roads in some places are actually buckling. Wisconsin has more than 50 road closures. The state of Delaware has seven buckled roads, and a driver’s car in Missouri even launched in the air because the road suddenly popped up before it went by.
STEVE INSKEEP, HOST:
Ow. Amit Bhasin heads the Center for Transportation Research at the University of Texas at Austin.
AMIT BHASIN: This is not very common because if you’ve designed and built a road correctly, this shouldn’t happen, but it does happen once in a while.
INSKEEP: Asphalt roads get soft in extreme heat, but road buckling is mainly a problem for concrete roads.
BHASIN: If the temperatures exceed what the road was designed for, you might have a situation where the road is not able to handle that movement. So you’ll see little bits of rock start breaking apart and chipping away from the surface.
MARTÍNEZ: Bhasin says there’s usually a joint in concrete roads where lines separate concrete slabs.
BHASIN: And like with any other solid, when the temperature goes up, concrete tends to expand. And that joint between these panels is actually intended for the concrete to expand and fill that space.
MARTÍNEZ: And when the temperatures drop, the concrete shrinks and opens up the joint. The joint is constantly opening and closing, and that’s exactly where the buckling happens.
BHASIN: If your concrete is not designed to handle a certain temperature and/or the temperature suddenly, you have this extraordinary heat wave and it expands more than what the joint allows it to, then it’s got no place to go.
INSKEEP: Turns out that every state builds its roads differently based on local weather, and as human-caused global warming changes the weather, states have to deal with it.
BHASIN: If I were in Texas and I was seeing 110 degrees temperature and my roads are designed to handle that, it would be perfectly fine.
MARTÍNEZ: Bhasin says it’s rare for road buckling to happen suddenly, but if you are driving on a concrete road that shows signs of it…
BHASIN: Just be careful. If there’s a vehicle in front of you, you might have some of these rocks that are flying onto your windshield.
MARTÍNEZ: Oof. He says when you notice too much cracking on the roads, let local agencies know so they can prevent a bigger and more expensive problem, like your car flying in the air.
INSKEEP: Ah.
(SOUNDBITE OF AC/DC SONG, “HIGHWAY TO HELL”)
