Av control a major operation

A closer look at what goes into avalanche control on the Trans Canada Highway.

We all know what it’s like to sit in our vehicles on the highway, waiting for the authorities to tell us that it is OK to pass, just as soon as avalanche control is done. But what is actually involved in shutting down a major highway?

For the roughly four or five times a season that the Ministry of Transportation and Infrastructure closes the highway east of Golden for avalanche control, highway crews have to scramble to make sure that everyone is out of the zone before any operations can start.

“First thing is we have to make sure we have flaggers at both ends of the canyon, and also at strategic locations like downtown. We don’t want traffic to get too backed up on the highway, it’s better to have people diverted in town. At least that way there’s facilities if it ends up being a significant closure,” said Blair Piggot, Quality Assurance Supervisor with HMC Services.

Once HMC has got everyone out of the zone, and does a sweep to be absolutely sure, then the Ministry commences operations. When the highway was closed last week that task was particularly difficult because four semis were spun out on a hill, one of which needed to be towed out.

The avalanche control itself consisted of a helicopter flying over with a “DaisyBell,” which is a device that explodes a hydrogen/oxygen mixture above the snowpack. The deposits of snow then fall, either into the ditches or across the highway.

“The first objective once they’re done with the control is go in and do whatever we have to do to get the highway open. Then we’ll come back in, usually within the next night or two, and start cleaning out the ditches from avalanche debris,” said Piggot.

The debris usually isn’t excessive, but can often spread across the entire highway. As HMC was clearing the zone just prior to avalanche control last week, there were small, naturally occurring avalanches starting to fall on the highway. The debris was not enough to cause damage on its own, but would certainly be enough to distract drivers, potentially causing accidents.

“You can tell the avalanche techs made the right call because snow is already starting to come down,” said Greg Ehman, division manager with HMC.

Avalanche control often comes at inopportune times, such as last week when crews were already dealing with heavy snow fall and spun out vehicles.

“Sometimes it’s a little bit short notice, but that’s just the nature of it,” said Piggot.

Communication has also become a major part of operations, as websites like DriveBC like to keep travellers as up to date as possible.

Predicting opening times can often be difficult, with most cleanups taking  HMC crews roughly two hours.