Pothole season in Winnipeg this year could be taste of what's to come with climate change

Water-filled craters have partially swallowed vehicles.

A midwife on her way to a delivery blew two tires on her vehicle after hitting an unavoidably large hole.

Streetcar tracks from a bygone era have become exposed, revealing the extent to which Winnipeg's approach to street maintenance has often simply patched over the past.

These are just some of the images and stories Winnipeggers have seen as potholes have appeared at an alarming rate this spring, and it could be a taste of what's to come as climate change wreaks havoc on our city roads.

This season's pothole situation has been exacerbated by an enormous amount of precipitation and an extended freeze-thaw cycle.

And Manitobans can expect more periods of intense rain and snow, more extreme temperatures and longer freeze-thaw cycles, says an engineer who specializes in pavement design and highway materials.

"We have roads that were built 40, 50 years ago facing new temperature extremes that they were not designed for and never experienced before," said Ahmed Shalaby, a professor of civil engineering at the University of Manitoba.

That increases the stress on our roads and shortens the lifespan of infrastructure that in many cases is already approaching its replacement point.

Newer road designs account for climate change, but roads that are decades old were built when less was known about its effects and how to address the problem, Shalaby said.

And as bad as this spring has been, the worst effects might not appear until this summer, he said.

Periods of extreme heat, like those Winnipeg experienced last summer, cause pavement roads and sidewalks to expand.

"When these roads are trying to expand during a heat wave … there is not room for them to expand, and then they end up buckling and creating abrupt failures," he said.

"The understanding is that with this continuing climate change, we may see even an epidemic of those types of failures in the future."

Climate impacts

A 2016 report by Natural Resources Canada and Transport Canada examined the expected impacts of climate change on the country's roads and other infrastructure.

Its recommendations include mandating the use of more permeable materials to reduce runoff, such as porous asphalt or concrete. These materials are made using regular asphalt or concrete, with the finer aggregates removed, resulting in pavement with a matrix of pores that allows water to permeate through the surface.

The report also calls for new rules limiting construction and elevating roadways in areas prone to flooding. It also recommends widening culverts and designing drainage systems to divert water away from roadways to reduce erosion.

A well-designed, built and maintained road should last up to 50 years, and longer if it's made with concrete, said Chris Lorenc, president of the Manitoba Heavy Construction Association. 

Using more durable materials comes with added costs, however. Winnipeg streets are typically paved with asphalt instead of concrete, which can be two to three times as expensive.

The problem Winnipeg is experiencing now has been years in the making, Lorenc says.

"We've had at least two extended, hot summers with not a lot of moisture, followed by an incredible winter with incredible volumes of snow and a wet spring with the freeze cycle."

Limited resources to fix problem

In 2018, the City of Winnipeg released its State of the Infrastructure Report, which gave the city's streets a C+ rating overall. The report pegged the average age of Winnipeg's streets at 48 years, and estimated the average lifespan at 73 years in total.

And the problem extends across Canada. The most recent Canadian Infrastructure Report Card released in 2019 assessed nearly 40 per cent of the country's roads and bridges as being in fair or worse condition.

A spokesperson says the City of Winnipeg has made updates to its design methods, including using "expected climate data to simulate pavement performance and deterioration over time" to produce long-lasting pavement.

The spokesperson says the city has made material improvements to the granular base used under the pavement and for the concrete pavement. Updates to asphalt materials and methods will be released in the future, the spokesperson said.

The city has said it will spend a record $165 million on road repairs this year, but municipalities struggle to keep up with the needs posed by crumbling streets and sidewalks with the budgets they have, said the U of M's Shalaby.

"They are limited in terms of the sources of funding that they have. That will continue to be our problem," he said.

A new fiscal arrangement needs to be reached between the city and other levels of government, Shalaby said.

Lorenc says the taxation system in Canada, which limits the abilities of municipalities to impose their own taxes, was created at a time when local governments owned a fraction of the infrastructure they do today.

"The problem has taken us 20 to 30 years to create. It's going to take probably 20 to 25 years to try to repair. But if you don't have a plan, then you're planning to fail."