Jan 20 – British Columbia is rolling out the artillery and bombs for avalanche bombing. There have been closures on some major roads for the first time in decades as the province grapples with record snowfall and rain.
The province, third-largest by population, uses helicopter avalanche bombing, remote-triggered explosives, and howitzers to keep roads open. But nonetheless critical routes to Vancouver are being disrupted by avalanche control.
Extreme weather, including November’s torrential precipitation, a deep freeze in late December and an early January thaw, has weakened the snowpack. Mountain slopes are more prone to avalanches that can release without warning.
Avalanche bombing requires closing sections of roads while teams use explosives to pre-emptively trigger slides, which prevents the snowpack from becoming deep and unstable.
Record amounts of control actions
A section of Highway 1 through Fraser Canyon northeast of Vancouver needed avalanche control for the first time in 25 years.
On Highway 99 north of Vancouver avalanche control actions are three times the seasonal average. Some paths have produced avalanches big enough to hit the highway for the first time in over a decade.
Avalanche bombing in Allison Pass further south on Highway 3 has also been above average.
These highways were all damaged in November by floods. A busy avalanche control season is putting further strain on resources. The Coquihalla Highway near Hope just reopened on Wednesday. And record snow along with avalanche risk delayed repairs to Highway 1 through the Fraser Canyon.
Further east avalanche teams in Rogers Pass, which runs below 135 slide paths in Glacier National Park, are dealing with more snow than usual. Control missions are also above average.
Approximately 3,000 vehicles traverse Rogers Pass every day in winter. A major Canadian Pacific rail line runs along the highway although it has a long tunnel under the top of the pass.
Rogers Pass avalanche bombing involves artillery soldiers who are stationed in Rogers Pass in winter. They use a howitzer to fire shells into loaded avalanche paths along the highway.
“Our goal is to bring down as much snow as we can and bring the hazard down to a point where it’s safe to open the highway,” said Jim Phillips, acting avalanche operations coordinator for Parks Canada.
The Rogers Pass program has been running since the highway opened in 1961. Before that, and before they built their tunnel, CP trains ran a high risk of deadly snow slides. One killed 62 railway workers in 1910.
So far this winter the team has fired 333 howitzer rounds, produced 197 controlled avalanches and closed the highway for 43 hours over seven separate days.
Helicopter Avalanche Bombing
Phillips said his team also uses heli-bombing and remote-trigger systems to set off detonations, and spends C$600,000 ($480,346) a year on explosives alone.
“It’s a balancing act. You want to keep traffic moving and minimize closures, but also minimize risk to people using the transportation corridor,” he added.
Avalanche control is typically needed until late April or early May.