Mountain Safety
January 11th, 2017

The Effects of Compaction on Avalanche Terrain


Boulder Mountain, Quartz Creek, Eagle Pass and Clemina are all names of popular riding areas that are likely known throughout the majority of the snowmobile community. We call these “managed” areas, as they are under an agreement between a snowmobile club and the province and are your typical “go to” spots for the average mountain sledder. These areas receive a lot of compaction.

The word “managed” may be a bit misleading. The typical agreement has local clubs or organizations maintaining a groomed trail only that may or may not lead to an alpine shelter as its final destination. Many of these access trails are mechanically groomed and are the access points for a variety of areas including treeline and alpine terrain.

Naturally some of these areas are quite busier than others and some can see hundreds of users over any given weekend. Regular winter season use of these areas can begin as early as November and continue well on into May.





Why is this important to us? 

Have you ever skied or snowboarded a super steep run at a large ski hill? Was it between 30-45 degrees or even steeper? Did it have convexities? concavities? Was it in sparsely treed and generally open terrain? If you answered ‘yes’ to most of these questions, then it sounds like it was potential avalanche terrain to me.

But why would a commercial ski hill allow you on avalanche terrain? They must be quite confident that the snow is not going to move. Maybe they manipulated the snowpack to aid stability? Sure they could have been using explosives a time or two to clear out tough-to-reach areas, but explosives are very costly.  There are a few other common forms of manipulating a snowpack often used by these operations: having skiers consistently track up the layers, ski-cutting and boot-packing. But what does any of this have to do with sledding?

You may or may not be familiar with the term “compaction”. We use this term to address numerous methods of manipulating a snowpack from its natural state.

I feel this topic is important to the snowmobile community due to the fact that compaction can drastically affect slope stability, and if we look at the amount of use our popular snowmobile areas receive, we cannot rule out some sort of effect on the snowpack from compaction.

And I wonder…  is consistent and widespread use of more popular managed snowmobile areas creating a growing and dangerous sense of overconfidence in mountain terrain? 


Compaction at Allen Creek

One of the areas in the province I am most experienced with is Allen Creek, near Valemount, BC. It is a very large area that is bound on all sides by legislated wildlife closures, leaving boundaries that are quite clear. Allen Creek has the same features as any high alpine mountain environment. The area offers a large mix of accessible terrain with ATES classifications ranging from non-avalanche terrain to simple, challenging, and complex areas.

At times, during periods of extended drought, fresh lines can be difficult to find at Allen Creek as it is one of the most heavily trafficked managed snowmobile areas in Western Canada. It is not uncommon after a busy week to see 80% of the terrain within the area’s relatively large boundaries resemble a parking lot—with every morsel of recently fallen snow having been absolutely steamrolled. This phenomenon continues from the start of the snowy season (mid-November) to the last round of rides for the average recreationalist, typically in late April or early May depending on the year.

Compaction of the annual snowpack within the area’s boundaries is extensive. Often at times of infrequent snowfall there is little terrain left untouched. This includes slopes of 45-50 degrees or greater, as well as features such as concavities, convexities and creek beds gullies at all aspects and elevations including treeline and above. 

As riders are becoming more skilled and pushing the technical limits of their sleds, it is becoming more difficult to find a location within Allen Creek (and many other managed snowmobile areas for that matter) that hasn’t seen a season’s worth of sled traffic.


It is not uncommon after a busy week to see 80% of the terrain within the area’s relatively large boundaries resemble a parking lot—with every morsel of recently fallen snow being absolutely steamrolled.

It is not uncommon after a busy week to see 80% of the terrain within the area’s relatively large boundaries resemble a parking lot—with every morsel of recently fallen snow being absolutely steamrolled.



Human Factors and Decision-Making

Over the last eight seasons of frequenting these areas (multiple times a week) and having to regularly search for that elusive unaffected location for stability tests and a quick profile, I have started to spend a significant amount of time thinking about the effects of compaction in these popular public snowmobiling areas. 

Extensive compaction from snowmobiles not only has relevance to stability and avalanche hazard but it also exerts a strong influence on the riders in the form of what we commonly refer to as “Human Factors” such as familiarity and consistency. These two human factors—things that influence our decision-making—are known to be the root of many incidents in the backcountry. 

How many times have you heard, “I have never seen that never slide before” or “I have ridden here for years and never seen an avalanche”?

Managed areas in BC encompass extensive avalanche terrain ranging from simple to complex. On a daily basis I witness some crazy decision-making in these areas with regards to terrain choices in relation to current avalanche conditions. Yet we rarely see large avalanche activity within these areas. 


This is big!

Could one’s level of familiarity with a certain busy riding area be causing them to consistently make poor terrain decisions? 

Is it possible that due to the heavy mechanical compaction within these riding areas that users develop a sense of overconfidence in their own decision-making skills?

What happens when these areas do not receive their typical compaction levels that one may be used to? Or when someone who is used to a compacted area decides to venture into less travelled terrain?



Remote trigger slide in virgin terrain.



The Effects of Compaction and Overconfidence

I often think about the effects of compaction within these popular areas.

Managed snowmobile areas throughout British Columbia receive hundreds if not thousands of user days per weekend, and many thousands per season. This has a profound effect on the snowpack and the avalanche hazard within these regions, and is likely a contributing factor as to why we don’t see more incidents involving snowmobilers given the nature of the terrain they travel in. The majority of the snowpack within managed areas is simply compacted to such an extent that it behaves more like a modified snowpack than that of the less frequented backcountry.

Much of the public’s riding takes place in, or travels through complex terrain. On any given winter day in BC, there are recreational snowmobilers with unknown levels of training moving through large expanses of alpine terrain. We all have the freedom to choose where we go, and the vast majority of riders come home safe at the end of each day.

However, I believe the presence of extensive compaction in these heavily used managed areas is resulting in non-event feedback that is developing an inflated and dangerous sense of overconfidence amongst some riders in avalanche terrain.


How to Deal with it?

How do we address this growing and likely unfounded sense of self-confidence and complacency in mountain terrain?

Some people have warned me that bringing compaction up in public discussions would cause too much confusion. It needs to be stated that terrain use decisions SHOULD ABSOLUTELY NOT be based on the potential for compaction alone. However, if we do not openly discuss the idea of compaction within these areas and its potential benefits and dangers, are we withholding potentially life-saving information?


Here’s the kicker…

If we look at this season, we have an unconsolidated snowpack in most areas of the province below 1800m.  We had trucks driving up many access roads well into December and I know that in my area, we could not get to many of our “hot spots” due to the lack and quality of the snowpack below 1800m. 

In reality we are just beginning to get to some of these areas and this delay in access has allowed the snowpack to develop unmolested in many treeline and alpine areas.  And by unmolested, I mean that we are dealing with layers in the snowpack in their natural state. This is happening in many areas where riders are used to sledding on a snowpack in which its layers have been mixed up by traffic under normal circumstances (whether they were aware of it or not).  What’s scary is that our current snowpack in its natural state in most areas of BC likely consists of deep basal weaknesses, mid-pack surface hoar/faceting and now some serious windslab development.

This is where familiarity, complacency (human factors) and unknown mistakes made over the last many years could now come into play and lead riders to make bad decisions on a current snowpack that is not as modified as they may have become accustomed to.



What did we miss? We better figure it out. Do we have the skills and experience to know?


I believe the recreational snowmobile community needs to be made more aware of the impacts of compaction in these heavily frequented areas. Even if the message is simply that on a high hazard day, a managed area may provide you with a safer experience than an untouched and raw backcountry destination. Although this is not always the case, and I believe we are experiencing this now with the unusual season we are faced with.

My intent is to effectively convey this message without causing more harm than good.  After all, compaction is by no means a guarantee (especially in a year such as this one). It could simply be one additional piece of the decision-making puzzle and if we do not discuss it, we are withholding valuable information.


Thank you for reading.  If you feel strongly about this idea one way or another, I encourage constructive feedback and information sharing and would happily engage in further discussion. 



Ride safe.





Curtis Pawliuk is the owner/operator of Frozen Pirate Snow Services and can be reached for discussion at