Spring is slowly but surely making its way across the northern U.S. In New England and parts of the Midwest and Plains, this is a time of year when temperatures frequently bounce above and below freezing.
As the climate changes, those freeze-thaw cycles are also happening earlier in the winter, and more often. Mix in increasing amounts of precipitation, and you’ve got a recipe for a lot of potholes on the roads. That means more costs, and complications, for municipal public works departments and their limited road repair budgets.
On an overcast April day, Jason Benjamin and a crew of four from Winooski, Vermont Public Works descended on East Spring Street, which was riddled with potholes, cracks and ruts. So the crew got to work.
One used a leaf blower to clear debris and water from potholes, while others shoveled heated asphalt from the back of a truck into the trouble spots, then tamped it down.
Normally, they’d use a machine to flatten the asphalt, Benjamin said. But it was having some trouble, so they tamped by hand.
“Doesn’t do as good of a job, but it still lasts quite a while,” Benjamin said. “Just not as efficient … I am sweating.”
This was just a temporary fix, Benjamin said, to keep the roads safe for drivers in the short term. The crew will come back in the summer to make a more permanent repair.
After a relatively warm, wet winter, they’re doing a lot of this kind of work this year.
“It didn’t freeze as good this year, and we’ve had a lot of wet snows and the roads have opened up quite a bit,” Benjamin said. “So we’ve got a lot of potholes we’ve been dealing with.”
All that moisture causes problems for pavement, according to Jo Sias, a professor of civil and environmental engineering at the University of New Hampshire.
“Pavements are designed to be dry,” she said. “That’s the whole reason why we have payments is to protect that soft, underlying natural material.”
That underlying natural material gets wet when pavement starts to crack. Then, when the temperature drops and that water freezes, it expands and causes the pavement to crack even more.
“It’s kind of a downward spiral,” Sias said.
The cracks get bigger, the underlying material gets softer, and cars and trucks run over it.
“And then you start getting those chunks that fall out,” she said.
Now, you’ve got a pothole. The short-term solution is to do what Jason Benjamin and his crew do: Fill it in. Recently, that’s been happening more often, said Winooski’s Public Works director, Jon Rauscher.
“The amount of potholes has gone up. Our budget necessarily hasn’t gone up to address those, unfortunately,” he explained.
Rauscher said his department has had to do temporary pothole repairs earlier in the winter too, because those freeze/thaw cycles are happening earlier in the season, like in January and February. And, Vermont is getting wetter. Annual precipitation has increased 21% since 1900, and more of it is falling as rain rather than snow in the winter.
Meanwhile, Rauscher said, the price of asphalt shot up in the last few years.
“So that obviously limits how much paving we can do for the season,” he said.
He’s competing for the same property tax money as other parts of city government, like the police and fire departments. So, Winooski’s backlog of road repairs is growing.
The city is not alone. According to a 2021 report from the American Society of Civil Engineers, the country as a whole has a $435 billion dollar road repair backlog.
So what’s a municipal public works department to do? For one, Jo Sias said they should start using future climate projections, rather than past data, when planning paving projects.
“Current practice is typically, to just say, ‘Oh, yeah, this is what the climate was [the] last 20 years, this is what we should design for,’” Sias said, “Rather than, ‘okay, [the] next 20 years could be different in some respects.’”
Another tip: Don’t just fix the pothole when one forms, Sias said. Pay attention to the root causes, such as drainage issues or cracks in the asphalt.
“It’s like changing the oil in your car, right? If you don’t change the oil in your car, you’re gonna have bigger issues down the road,” Sias said. “But if you do that maintenance, you’re expecting that to last longer. Pavements are exactly the same.”
They’re not perfect fixes, but they could help cut down on the time crews spend tamping asphalt into potholes.
