Officially, “A Merging of Theory and Practice.” But when you combine jetlag with a location two blocks away from the famed Innsbruck Golden Roof, caffeine and crowds are themes. The event was held last month at Congress Innsbruck, a beautiful convention center near the main tramway station, next to the Inn River. A wall of mountains rises above the complex. With a chill in the air and autumn leaves skittering in the breeze, despite the population of about 130,000 you get the distinct feeling you’re in a mountain village rather than a metroplex. Just fractions of a kilometer away from here, you can practice the alpine sports that snow avalanches are such an influence on.
In reporting the conference, I’ll do a three-part narrative touching on the presentations I found most interesting or useful from a ski touring and mountain living perspective: “blogger’s take.”
“Protection measures” such as defense structures and stability structures are out of my usual gamut. Nonetheless, due to our backcountry development projects, I find these things to be interesting and enjoyed related presentations. Apparently, it is not uncommon for rockslide defense structures (nets and such) to be exposed to snow avalanches. As well as the opposite. Thus, there was a discussion about building these things in such a way as to serve both purposes.
The takeaway I got was that while rockfall impacts can be strong, upwards of 500 kilo-joules, the pressure of snow pressing against the nets can be immense as well — and loads broadly instead of producing point impacts. More, some of the rock nets have brake systems that lack a repeating function. The brakes are perhaps triggered by the snow weight, with subsequent maintenance issues (resetting or otherwise renewing the brakes). When they build the rock and snow nets, constructors sometimes set up elaborate systems using temporary walkways and cranes. Crews tasked with upkeep don’t have those benefits, so nets need to persist in performance. Overall, I now have a new appreciation of the nets and fences one sees while riding the trams and driving the roads of the world.
Next up, “rock mechanics researcher” Thomas Boone, also a backcountry skier, gave a fascinating presentation that spoke to where the energy comes from that pulls the avalanche slab from the snowpack: the so-called “fracture energy.” He derived his take from the fracture mechanics of rock. As most of us know, the “collapse” of the snowpack on a weak layer, along with the snowpack weight, are where the energy comes from. It was cool to see this viewed from a more scientific aspect. Boone closed his talk by wrapping back to how this relates to the hand compression tests we use in avalanche hazard evaluation. His take was overall favorable to compression tests, but noted his work indicated the Propagation Saw Test (PST) might not be so great. I’ve never used the PST in real life situations, so no worries on my part. But those of you who spend extra time in your pit work due to the PST might want to consider your options.
You ever driven Rogers Pass on the Trans-Canada Highway? A presentation by Chris Argue gave up a few factoids that could add interest when you’re driving up there for a ski tour: You are rolling under more than 150 avalanche paths. Control work is done with a combination of helicopter bombing, 17 gun platforms for their artillery, snow nets at Cougar Corner (said to be the largest net install in the western hemisphere) and RACS (remote avalanche control systems) towers. The latter are interesting devices that drop an explosive charge on a rope, when requested remotely. They’re re-loaded via helicopter.
The gist of Argues’s talk was that an enormous avalanche safety project was initiated in 2015: The “Trans-Canada-Highway Avalanche Mitigation Project for GNP” addresses everything from detection to control. The commonality in this, found throughout the world, is an ever-increasing use of RACS towers. For example, in another presentation about avy risk management at Ischgl, they mentioned that 134 RACS towers had already been installed, with more on the way. It seems the things are so effective the powers can’t get enough of them. The trick in the U.S. will be RACS in legal wilderness, or not. They’re rather civilized. In any case, 134 towers on the Ischgl slopes? That’s industrialization, nothing less.
On the same subject of major highway improvements, Bill Nali of the Utah Department of Transportation did a short talk about Utah’s Little Cottonwood Canyon and what they’re doing to fix it. We’re talking a 23-kilometer road with 64 avalanche paths and bumper-to-bumper travel of about 12,000 cars daily.
Apparently, calculating the Little Cottonwood avy risk levels burned up a computer CPU or two, but not until they’d convinced Utah to build 1,000 meters of snowsheds at a cost of 65 million dollars. Along with that, they plan on adding plenty of Gasex and RACS remote trigger devices. While the end result won’t be complete for a while, I’m sure it’ll be appreciated by the people living in houses underneath the artillery target trajectories. You know, things like human error… In my case, once the snow sheds are in I’ll miss the window views up the throat of the beast, but then, I won’t be sweating fear as I sit there in the stop-and-go traffic.
Overall a good day, with a bit too much structural engineering for my interests. The “softer” content comes over the next few days.
Thanks to one of our commenters reminding me, you can access conference abstracts and articles here.