By Canadian Press

Wood pulp, steel cables: Scientists study how to make ice roads last longer

Oct 13, 2019 | 7:03 AM

The road should have been frozen solid, but it was anything but.

When drivers tried to travel the Mackenzie Valley winter road in the Northwest Territories last March, it was an unpassable highway of muck well before its usual closure date. Four communities were left without vehicle access.

That’s what Paul Barrette — using everything from steel cables to wood pulp — is working to prevent.

“It’s the only time of the year, those two or three months, when northern communities can resupply their needs in fuel, construction material and other bulk goods,” said Barrette, who leads a National Research Council team that is developing ways to keep winter and ice roads passable in a warming climate.

“What we’re looking at is to ensure those roads remain operational throughout these warm winters.”

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Across Canada, there are at least 10,000 kilometres of roads that depend on freezing temperatures. Most are in Ontario, but they exist in four provinces and two territories.

For dozens of isolated communities, they are the only way in and out that doesn’t depend on a boat or plane. They are a lifeline for many resource projects.

Improved construction methods have slightly lengthened openings for most winter and ice roads.

But the number of days with freezing temperatures is shrinking across the North. Yukon and the Northwest Territories have already warmed 1.5 degrees Celsius, nearly three times the global average.

A study of the winter road that leads from Yellowknife to the diamond mines of the Central Arctic predicts it will be unable to carry any heavy loads by the end of the century.

“If such a projection were to become reality, the (Tibbett-Contwoyto Road) and other winter roads in the region would no longer be viable to support the natural resource industry in northern Canada,” the study says.

Barrette said the problem is often the few hundred metres it takes to cross a river or a lake.

“The weakest link often happens to be over ice. When that happens, the road remains closed a whole winter so the community remains stranded a full year.”

Ice is tricky. It’s not as rigid as it seems and slowly deforms under a load.

“It creeps,” said Barrette. “Say you park your vehicle on the ice. If you leave it there two or three hours, the vehicle may break through.”

Barrette and his colleagues are looking for ways to stiffen the ice and stop the creep.

In the past, operators have dropped logs onto the road and frozen them into the ice. But felling trees over the same spot year after year creates environmental issues. Besides, there are no trees further north in the tundra.

Barrette is looking to other materials. “Wood pulp is a possibility.”

Mixing wood pulp into ice hardens it. The blend was used during the Second World War to create an experimental aircraft carrier.

Laying steel cables into the ice is another possibility.

Most recently, Barrette has experimented with what are called “geotextiles” — in this case, a sheet of polypropylene mesh frozen into the road.

“They’ve got to be light enough, they have to be cheap enough, to be brought over on site,” said Barrette.

They also have to be environmentally sound. And they have to work. Barrette said none of the methods have yet been tested in the field.

“We’re actually studying this now,” he said. “We’re trying to make this work.”

Barrette expects to have something he can field-test within a year, and says there is some urgency to help ice resist a warmer climate.

“Those on-ice segments are more sensitive to warm temperatures,” Barrette said.

“There is a risk of breakthroughs. Sometimes, the water’s deep.”

This report by The Canadian Press was first published Oct. 13, 2019.

— Follow Bob Weber on Twitter on @row1960 

Bob Weber, The Canadian Press