An avalanche spills down onto the Trans-Canada Highway in Three Valley Gap following avalanche control work by the MInistry of Transportation last Wednesday

An avalanche spills down onto the Trans-Canada Highway in Three Valley Gap following avalanche control work by the MInistry of Transportation last Wednesday

Keeping the highways open: Avalanche control with the Ministry of Transportation

The wind through Three Valley Gap was bitterly cold. I was standing outside, just behind the hotel, with Scott Mitchell from the Ministry of Transportation.

Around us, the highway was closed and the only sound was the wind gusting through and helicopters buzzing overhead. First, was a Ministry of Transport A-Star helicopter coming to the area to do avalanche control, followed by two helicopters from Eagle Pass heli-skiing, which uses the hotel as it’s base of operations.

My focus is on the ministry chopper. Inside were Val Visotzky and Ross Campbell, two ministry avalanche technicians, ready to do some avalanche control work on the slopes above the Trans-Canada Highway.

The helicopter moved into place and hovered above the avalanche start zone. Up to three explosive charges were dropped onto the slope below and the helicopter backs off.

An explosion boomed across the canyon and snow tumbled down the mountain side, sliding onto the empty road, while a third avalanche technician, Greg Paltinger, watches from below.

This process was repeated along several slide paths through Three Valley Gap. Once the debris settled, a huge front-loader made its way along the road, clearing the way through the snow.

The highway was closed at 3 p.m. and re-opened at 5 p.m. It was a short, fast and easy compared to what came over the following days as several storm systems moved through the region and dumped copious amounts of snow and rain on the mountains around Revelstoke.

“It’s easy to close the highway, that’s real easy, but you can’t be doing that,” said Bruce Allen back at the ministry office following the control work. “The hard part is keeping the highway open and that’s the line we walk.

“We try really hard not to inconvenience people.”

Allen, who’s official title is district snow avalanche technician, is the man in charge of keeping commuters safe from avalanches along the highways around Revelstoke.

A highly quotable man, he has more than 30 years experience in the snow business, including 28 doing avalanche control with the Ministry of Transportation.

He works with three others – one assistant and two technicians – to monitor avalanche conditions and keep the highways open as best as possible.

Allen’s crew had a busy week. Following the work on Wednesday, there were further highway closures daily, on the Trans-Canada, on Highway 23 North and in Galena Pass.

A mixture of heavy precipitation, high winds and rising temperatures created an avalanche hazard that was rated high in most of the region and extreme in Glacier National Park. They witnessed numerous natural and controlled slides big enough to bury cars and in one bit of control work on the Laurie slide path just west of Glacier National Park, they triggered a class four avalanche that Allen said was “big enough to destroy a train, probably.”

“It was 3-400 metres across and an entire winter snow pack went to ground,” he added.

Explosive control work is the final step in the process of avalanche control. Before that, the crew members go out and dig snow pits and study the snow pack at 20 different sites around Revelstoke.

They also watch the weather and have 11 remote weather stations set up that monitor temperature, wind speed, wind direction and precipitation, said Allen.

“I don’t really care about snow. The amount of snow is irrelevant to me,” he said. “What’s relevant to me is precipitation amounts and precipitation rates.”

They then take all that information and try to figure out the risks of an avalanche. It’s no easy task – no computer programs exist that can predict when they will occur – so they have to rely on intuition.

“Experience has taught us what trends of weather will cause what kinds of avalanche and then we make a decision – do we do control?” said Allen.

On Wednesday, the day I was out, the decision was made to do control work a day early after the precipitation rate increased.

“What you saw today were not very big avalanches,” said Allen. “What we did was very effective because now we know we can get through the night without closing the highway.”

As he puts it, they’re not in the business of avalanche control but in traffic management.

“Avalanches, yeah, they can hit vehicles but it’s rare,” he said. “It’s usually the vehicles that hit the avalanches so we’re trying to manage the traffic in relation to the avalanches.”

Allen will allow small natural avalanches to hit the road if he thinks they won’t impact traffic. He said the Ministry employs a five point scale similar to what the Canadian Avalanche Centre uses to assess danger – low, moderate, considerable, high and extreme.

“At high the highway has to be closed because we expect large avalanches on the highway,” said Allen. “At considerable we can have small avalanches affect the highway and we find that is acceptable because they won’t adversely affect the traffic. It’s a fine line.

“If things get out of our comfort range we’ll shut the highway.”

After a chaotic week that saw much of the Trans-Canada closed between Lake Louise and Craigellachie for large periods of time (as of press time the highway was still closed east of Golden), the highway was fully open in and out of Revelstoke Sunday night.

The storm cycle that hit the area was a once-a-winter occurrence, said Allen.

“We’ll see if this is the only one for the winter or if we get more, then it will be a little more than normal.”