Recent storm reveals need to prepare Atlantic Canada’s roads for repeated downpours, experts say


Damage to Oregon Road after a bridge was washed away in Tarbotvale, Nova ScotiaNova Scotia Department of Public Works

Atlantic Canadians living along highways cut off by torrential rains this week say it’s high time governments focused on upgrading highways to ensure they can survive expected downpours. become more frequent.

“It was a wake-up call, and we’ll probably need a few revivals before we start preparing for it,” Peter MacGillivray said Wednesday after two culverts on Highway 245 near his home in northern Nova Scotia. were washed away by the last storm.

The 59-year-old said he was using his four-wheeler and a forest road to get from his home to an undamaged part of the highway after the culverts could not withstand around 116mm of rain in two days.

In southwestern Newfoundland, which was hit by the same storm, Joe Murphy said winding rural roads along the coast were already in poor condition and residents have been saying for years improvements were being made. required.

“If we’re going to have monstrous storms and we have poor infrastructure, it’s obviously going to cause a lot more damage,” the resident of Codroy, Newfoundland and Labrador said Thursday.

Nova Scotia reported on Wednesday that 25 roads had been washed away in three counties, with northern Cape Breton the hardest hit. Meanwhile, in southwestern Newfoundland, the storm closed portions of the Trans-Canada Highway and isolated some communities.

While provincial officials say new road construction takes climate change into account, Canadian experts argue that engineers must do more to assess the risks – and Ottawa and the provinces must spend more to avoid repeated incidents.

A federal climate change report released in April 2019 indicates that the consensus of Canadian researchers is that the number of extreme precipitation events lasting several days is expected to increase on the east coast. The report says that if current global carbon emissions continue, Atlantic Canada will experience a 12% increase in annual precipitation over the next century and a 30% increase in storms in ten that produce heavy rain showers.

Slobodan Simonovic, director of engineering studies for the Institute for Catastrophic Loss Reduction, said a fundamental overhaul is needed on how to design roads to accommodate these predictions. “Everything that happens in Canada, we keep repeating the same mistakes, and I’m puzzled the message is not reaching anyone,” said Simonovic, professor of engineering emeritus at Western University in London, Ont.

Instead of relying on standards that use historical information to size culverts or specify platform materials, he said civil engineers should make “performance-based” calculations of how a given section of the road can survive storms. “We have to simulate a given structure under various conditions… and I generally recommend then choosing an option that can maximize the resilience of the structure,” he said.

Blair Feltmate, director of the University of Waterloo’s Intact Center for Climate Adaptation, noted that there are well-established ways to adapt existing roads to heavy rainfall.

These include protective berms, canals to divert stormwater from highways, and retention ponds to keep water in safe places. There may also be methods of placing natural features near roads to absorb water before it spills onto the roadway, he said, and systems can be put in place to remove debris in the road. culverts and avoid blockages.

“We know what to do. The problem is that we are not taking actions to mitigate the risk of flooding, ”he said in an interview on Wednesday. “We live in illusion.”

Tim Webster, head of the applied geomatics research group at Nova Scotia Community College, says improved computer modeling is needed to predict the risk of heavy rain for roads. It should cover the whole province, he said, rather than “the fragmented patchwork that exists today.”

However, Peter Hackett, the Deputy Minister of Public Works for Nova Scotia, said in an interview Thursday that his engineers are dimensioning ditches and culverts to withstand the most severe storms of the past 100 to 200 years, and are also holding account of the slope of the land. is near the roads.

“On our new constructions, we try to take these elements into account with localized calculations… on how we can capture the water without it destroying the infrastructure,” he said. It is more difficult to renovate the old roads that bypass the mountains and along the coasts to fully protect them from runoff, he added.

As for improving the modeling, Hackett said the department has yet to map the entire network for climate risks, but he supports the concept.

“We are doing the job that we can. I think we do a good job, and when things do happen, we have to go out and fix them. But we are trying to move forward, ”he said.

With files from Danielle Edwards.

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