Hate those pesky potholes? You won't like what's coming with climate change

Whether you're drivinga car, ridinga bikeor just enjoying a sidewalk stroll, potholes are annoying, dangerous and expensive. So be prepared as the spring thaw begins in much of Ontario, so too doespothole season.

Over the years, CBC stations have told hundreds of stories about problems with potholes in areas of Ontario and across Canada. Rapidly deteriorating roads alreadycostCanadians an extra $3 billion in vehicle upkeep every year, according to the Canadian Automobile Association.

So we should all be concerned about the havoc climate changecouldwreak on our streets, with cities already preparing for more potholes, bumps, cracksand ruts.

Fortunately, engineers have been working to develop better, longer-lastingand more sustainable materials,with innovations like self-healing asphalt androads connected to artificial intelligence (AI) technologythat can help predict where cracks and potholes will develop.

Canadian climates perfect for potholes

Canada encompasses many different climates, but it just so happens that many of them already provide perfect conditions for potholes in the spring.

"Any time [temperatures] start fluctuating back and forth between above zeroand below zero, especially if those shifts are large, that's basically pothole season,"said Scott Berry, operations manager of roads and traffic for theCity ofKitchener.

"Whether that's happening in January as a short little week instead of being cold, or whether it's happening in the traditional pothole season of March andApril and May that's what is contributing significantly to potholes on roadways."

WATCH| Learn more about how potholes are formed:

How potholes are created

5 years ago

Duration 1:28

Pothole season is well under way. This is how potholes are created, and why they feel worse some years than others.

This is known as a freeze-thaw cycle, and such cycles are common across Canada, saidAli Nazemi, an associate professor of building, civiland environmental engineering at Concordia University in Montreal.

The problem for roads comes when water infiltratesthe subbasebeneath the top layer of asphalt and undergoes freeze-thaw cycles.Water is the only known non-metallic substance that expands when frozen,and it exerts a lot of power when it does.

"When [water]expands, it starts putting pressure on the soil and infrastructure ...it cracks the infrastructure," said Nazemi. "Then when it's getting thawed, the water droplets startto move toward those cracks that it previously made, and then another cycle of freezing happens and the pore expands."

The more freeze-thaw cycles occur, the more of these expanding, ice-filledvoids form beneath the top layer of asphaltand the larger they grow.

"If this cycle carries on, that basically increases the speed of deterioration of the infrastructure quite significantly," Nazemi said.

When it warms andthe ice melts, the top layer of asphalt is unsupported. Asa truck or other heavy vehicle drives over that spot,the asphalt can giveway, revealing the voidunderneath.

And so a pothole is born.

Could potholes become year-round issue?

Using novel modelling techniques and data from remote-sensing satellites, Nazemiwas senior author on a 2021 Journal of Hydrology paper and a 2022 Nature Scientific Reports paperthat highlight somepreviously overlooked key impacts of climate change in Quebec. He is currently applying those techniques to a pan-Canadian model.

His research suggests the transitional seasons before and after winter will grow longer, meaning more temperatures around zero and more freeze-thaw cycles, threatening infrastructure across the country.

That'san issue for cities and those using the roads, said Scott Berry, the city operations manager in Kitchener, Ont.

"If that happens, then we will have a longer pothole season. It won't be just contained to March, April and May. You might see pothole season creeping its way into all of February at some point."

There are many other waysclimate change will affect our roads, said HassanBaaj, a professor of civil engineering at the University of Waterloo anddirector of its Centre for Pavement and Transportation Technology.

Extreme heat in the summers means an increase in rutting, where depressions in the asphalt are worn by the tire tracks of heavy vehicles. Increased precipitation can result in flooding and damage roads, and more sun exposure degrades the asphalt and forms more cracks that water can infiltrate.

Of course, the best way to prevent additional damage to our roads is to reduce emissions.But since we have already committed to several decades of warming, researchers are looking atways to mitigate the damage.

There's actually 'self-healing' asphalt

Researchers have long found ways to produce "better" asphalt, said Baaj, includingchangingthe mixto make the asphaltmore resilient, easier to produce, require less maintenanceor even be self-salting.

"We're working on developing high-performance asphalt mixes that have high resistance to the different modes of deterioration of pavements."

In recent years, sustainable engineering has been the name of the game. That means theinnovationsthat engineers are exploring are expected to be long lasting and environmentally friendly.

As one example, Baaj cited"self-healing" asphalt,which is inspired by the biology of the human body.

There are numerous ways to do this.One involves injecting bacteria into the asphalt. When exposed to water, the bacteria produce calcium carbonate, sealing up any cracks with limestone.

There's also smart asphalt roads powered by artificial intelligencethat helps predict and detect cracks well before they canbe detected at the surface, making repairs cheaper, easier, quickerand more effective.

"We have different instruments that are embedded within the different layers of the pavement [and] transmitters that will collect the data and send it to our team at the University of Waterloo to be analyzed, using algorithms that we will be creating using artificial intelligence," said Baaj.

"When we see patterns, when we see like things happening like high stresses, etcetera, we would be able to connect those events that are happening in the pavement and future events that will happen later, like cracks that will appear."

Research is also underway to find more environmentallyand climate-friendly alternatives to traditional asphalt, which uses the crude oil product bitumen as a binder and is known to release harmful air pollutants for years after being laid down.

In Thunder Bayin northwestern Ontario and a couple of other Canadian cities, a pilot project is underway toinvestigate partially substituting an alternative binder called lignin, a plant polymer and abundant waste product from paper mills.

Baajis also working onrecyclingold pavement to create new, more resilient asphalt while keeping the old materials from going to waste. He saidit's more complex than you maythink, but well worth it.

"If we use recycled materialsin a good way, we will buildresilient roads that will be as good or better than the ones that are not using the recycled material. So I'm not creating a problem for future generations to deal with ... my successors will have to deal with that. My kids will have to deal with that."