How local governments are protecting roadways from climate change

As climate change alters weather patterns, local governments in Winnipeg, Saskatoon, and Regina, along with provincial authorities in Saskatchewan and Manitoba, are taking steps to protect Prairie roads from more intense weather.

Cities brace for more frequent freeze-thaw cycles

The biggest concern for Prairie cities is that climate change will lead to frequent freeze-thaw cycles, which can cause cracking and potholes, requiring more frequent resurfacing and increased road repair costs.

To mitigate this problem, Regina began installing geotextiles made from polymers, like polypropylene, into its roads when rebuilding them.

As a separator, geotextiles prevent the intermixing of the different layers that make up the road, such as between the soil and asphalt aggregate. This minimizes erosion that leads to frost heave, as the geotextiles allow water to pass through the road while keeping the dirt in place. 

“Geotextiles do not require any additional maintenance and have contributed to overall cost savings because this practice increases a road’s lifecycle,” a City of Regina spokesperson wrote in an email to The Flatlander.

In Saskatoon, a crack sealing program was implemented to combat the damage caused by freezing and thawing, said Todd Grabowski, Saskatoon’s engineering manager of asset preservation.

Saskatoon uses the rubberized asphalt sealing compound called Crafco Roadsaver 522, applied hot to cracks no larger than 4 cm. 

In Winnipeg, the city is updating its asphalt mix to include polymers. These chains of repeated small molecules have been shown to make roads more resilient to temperature fluctuations and to make the asphalt more resistant to rutting and cracking.

“Traditional materials may not withstand new climate conditions, requiring more durable materials and construction techniques to reduce maintenance needs,” a spokesperson in Winnipeg’s public works department wrote in an email to The Flatlander.

Preparing for more rain and snow

Another concern for local governments is increased precipitation. 

“More frequent and intense rainfall can cause erosion and water infiltration, weakening road foundations and necessitating improvements in drainage systems and road repairs,” wrote the Winnipeg public works spokesperson.

In 2020, Winnipeg began using open-grade materials in its road construction, specifically in the base and subbase–the two layers underneath the top part of the road that people drive on.

Open-grade materials mean there are tiny spaces in the roads that allow water to drain instead of leaving it to sit in the layers of the road, where it can weaken the asphalt and cause potholes. 

Across the province, Manitoba Transportation and Infrastructure (MTI) also use open-graded drainage layers underneath the highways to minimize the risk of erosion or washout in flood-prone areas.

Installing larger culverts to prevent road washouts

Manitoba has also raised the elevation on some provincial highways, such as Provincial Trunk Highway 75, to withstand flooding and replaced existing culverts with larger ones to accommodate heavier water flow associated with wetter conditions resulting from climate change.

Saskatchewan also started increasing the capacity of its culverts on the national highway system in 2014. Each year, the province replaces more culverts to meet the new standard.

Culverts are critical in moving water from one side of highways to the other, which helps protect the road surface by preventing flooding.

“The new standard helps ensure the province’s transportation network is more resilient to extreme weather and climate change,” wrote a spokesperson from Saskatchewan Highways in an email to The Flatlander. “For the larger culverts, there may be an increase in installation cost, but there is no change in the cost of long-term maintenance.”

‘Gutters’ for the roads

Saskatoon plans to incorporate edge drainage into its new road structures.

Edge drainage involves creating gutters along the sides of the road, which helps the water under the asphalt flow out and away. 

Without mitigation, wet weather or high-water tables “can potentially saturate roadway structures and compromise their strength,” said Grabowski.

Anticipating frequent temperature extremes

More frequent temperature extremes caused by climate change are also expected in the future, the City of Winnipeg spokesperson said. 

Higher temperatures can cause asphalt to soften and rut, while extreme cold can lead to cracking. 

MTI uses performance-graded asphalt binders, which are formulated to resist cracking and rutting in Manitoba’s extreme temperatures. 

When selecting asphalt binders for a project, MTI considers seasonal high and low temperatures and future climate trends. 

Over in Saskatchewan, Saskatoon’s asphalt mixes are already made to withstand temperature fluctuations ranging from -40 C to 40 C. 

Regina is developing a Climate Adaptation Strategy that will examine the impacts of climate change on municipal infrastructure, assets, services, and operations.

Meanwhile, the City of Winnipeg conducts internal assessments on how climate change may affect its roads and what improvements should be made to mitigate this impact.

However, Saskatoon has not conducted a comprehensive long-term climate change assessment, but its ongoing asset management plans include an infrastructure resilience and climate change adaptation strategy.

“Future assessments and studies will be considered, as needed, based on condition data and the performance of roadway assets to further assess the long-term impacts of climate change on our infrastructure,” said Grabowski.

For its part, MTI said its staff are up-to-date with academic and industry research that focuses on the effects of climate change on pavements and adopts best practices related to design and materials use.

“In the long term, these solutions will make the infrastructure more resilient and will save money on repairs stemming from extreme weather events or flooding,” the spokesperson from MTI wrote. “The department remains open to exploring options which will address challenges related to climate change in a financially responsible way.”

MTI is updating its spring road restrictions and winter seasonal weights programs and policies based on historical and future climate trends.