Avalanche control at Three Valley Gap
© Ministry of Transportation
Avalanche control at Three Valley Gap
Three Valley Gap received record breaking snowfalls for January

It's been a record year for snow levels at Three Valley Gap, roughly 20 km west of Revelstoke on Highway 1.

Although the season started below average in November, the Ministry of Transportation noted record breaking snowfalls for both December and January.

Three Valley Gap received 287 cm of snow in December, which is 171 per cent above average and record breaking. It also got 233 cm last month, which is 145 per cent above average and a new record for January.

Day after day, the snow has kept falling.

"It's been relentless," said Robb Andersen, senior manager of avalanche and weather programs for the Ministry of Transportation.
Andersen has been an avalanche technician for 25 years.

Andersen said that while the snowpack is different each winter, a defining characteristic for the 2019/2020 season is depth.

The terrain surrounding Three Valley Gap is steep, which creates snow instability. The snow doesn't have the strength to hold itself up before it starts to avalanche.

"It's a very challenging area," said Andersen.

If it wasn't for the remote avalanche system installed at Three Valley Gap, Andersen said Highway 1 would have been closed far more often this winter.

In 2016, the B.C. Ministry of Transport spent $6 million constructing four permanent towers at known avalanche paths in the Three Valley Gap.

The system triggers slides remotely, meaning avalanche control can be done overnight, which disrupts traffic flows less.

In the past, avalanche control was more dependent on daylight and good weather. It was more common for avalanche technicians to drop bombs on slopes via helicopters.

With the remote system, the installed towers fire explosives on nearby slopes. The explosives hang on ropes above the slopes, roughly a meter or two above the snow. When detonated the explosives gives the snow an air blast, which destabilizes the snowpack and creates an avalanche.

Currently, there are 11 remote avalanche control systems in Three Valley Gap and a total of 46 province-wide.

While the amount of closures has not decreased since 2013, the length of each closures has. For example, in 2014 and 2018 the road was closed 20 times. However, total closure time in 2014 was more than 106 hours, compared to less than 30 hours in 2018.

In some cases, the ministry said the length of highway closures have decreased up to 70 per cent.

However, the amount of closures have not decreased as the remote system allows the ministry to preform avalanche control more frequently, thereby preventing the snowpack to build too high, so the avalanches are smaller and easier to clean up.

With the remote system, Andersen said it usually takes five to 10 minutes to trigger avalanches. The part that takes the longest is the clean up. Typically, the larger the avalanches, the longer it takes to clear the road.

According to the ministry, Highway 1 closures can cost $500,000 per hour.

"The real cost savings of the remote system is reducing the closure times," said Andersen.

"Which has a huge impact on communities like Revelstoke."

Regardless, for a highway avalanche technician, the work never ends.

"With highways, you're constantly thinking about it," Andersen said.

Unlike ski hills, which conduct avalanche control during the day and closes at night, the aim is to keep Highway 1 always open. Thus, Andersen said there is always staff monitoring weather and snowpack stability.

Since this year is one of the snowiest on record, Andersen said his crews are getting worn down.

"We'll be happy for two weeks of sunny weather," he said with a chuckle.

According to Environment Canada, another 30 cm of snow is expected within the next week for Revelstoke.