The physics of snow clearing

Clearing snow is no fun, so over the years, I’ve come up with a few science-based improvements to my process. Well, even if my science is a bit rusty, surely any efficiency injected into this task is better than none, and what else am I supposed to think about when I’m moving snow?

Some principles:

  • Deep snow is heavier than light snow, so clear it early
  • Wet snow is heavier than fluffy snow, so clear before it gets wet
  • Pushing snow is practically frictionless, but gravity still applies, so lift as little as possible
  • Snow, water and ice all need  to go somewhere else, so think ahead to where you want them
  • Ice is a lot harder to remove than snow or water, so move it before it changes


Pushing is easier than lifting

Pushing snow around is much easier than carrying or throwing it. Ideally, one could push the snow to its final location, but more usually, the push ends with a lift, but at least it’s not being carried or thrown from the centre of the driveway. Typically I’ll use a wide pusher at an angle, just like the ploughs on the street, and run from the centre of the driveway down the length, gradually moving the windrow out to the side with each pass until it’s easier to do short pushes to reach the edge.

For heavy snow or ice, a snow scoop tool can be filled and then tilted back so that just a small surface is touching the ground. It’s then very easy to move giant loads as there is practically no friction. Of course, it’s best to leave enough snow on the track to keep it slippery, only clearing it up when the majority of snow is gone.

Timing your snow clearing efforts for best effect

If you have the flexibility to do so, several light passes are easier than one concerted effort. Unless you have a snowplough mounted on a vehicle, there is a physical limit to how much and how far you can push before the weight becomes too much. Clearing an inch of snow, it’s probably possible to clear a track from side to side or even top to bottom in one pass.

Depending on the weather, you may want to clear early when it’s light and fluffy, or clear it while it’s still slushy (it’s been semi-melting on the driveway) before it freezes or becomes a heavy layer of half-ice, half-snow which is impossible to push.

First thing in the morning, getting the dark driveway uncovered lets the sun do your work for you. (You did get a house with a South-facing driveway, didn’t you?)

Finally, you definitely don’t want to be trying to clear snow after it’s been compressed by the passage of many tiny feet or even one car, because ice doesn’t want to let go.

Don’t clear the same patch twice

Pull the snow away from the eaves trough

Think about the order you’re going to clear things. In general, go from high to low, centre to the outside, and enclosed areas before open spaces. If there is enough snow to warrant pulling it off the eaves trough, do that first, then decks and steps – top down, before doing the paths and driveway. (Clearing a foot or so of the roof will mostly prevent blocked troughs and icicles.)

If there are two of you clearing snow (what a luxury that would be!) coordinate things so that one person is not pushing snow through an area the other one has cleared.

In general, I like to clear a large area like a driveway starting with a long pass from top to bottom, and then work out to each side in turn. However, there is a spot by our garage where one side is not a good place to pile snow – my wife objected when I piled it outside the front door – so that area gets pushed down the driveway to where it can be moved off to the side. So I do this before the lower part is cleared.

When I’m using a snow thrower, some of the driveway snow tends to end up on the sidewalk however careful I am, so I try to remember not to do the sidewalks when I first reach them, but wait until I’m finished throwing snow over them.

Saving your back

So far, I’ve talked about getting the snow closer to its final location with the minimum effort, that is, by pushing it there. Sometimes, especially when I’m doing a final clean-up just before bed, that’s where it stays for the night, and the next day any further snow gets added to the pile before final disposition. If it’s a small pile of relatively light snow, I’ll just work my way along the row taking small bites and lifting it on to the lawn, taking care not to twist as I lift.

For heavier accumulations, for the last few years I’ve fired up the snow thrower just to run it through the snow I’ve pushed to the side. This saves the heavy lifting, and has the added benefit of not creating a wall at the edge of the driveway which can quickly turn into a four-foot impassible cliff, because the thrower spreads snow over a larger area.

Snow, water and ice

I always try to get my surfaces completely clear of snow. This is not just because it looks better, but also because any blobs of snow can semi-melt and then freeze into a rock hard protuberance which will stop a snow pusher dead in its tracks. (Gentlemen, never push a snow shovel with the handle directly in front of your body!)

Single pass in a car makes clearing harder
When footprints freeze, the uneven surface is dangerous
Clear a path to catch basins

Snow that has been compressed into ice is extremely hard to remove (typically it takes extensive chipping, or ice melting chemicals.) It can be very slippery, especially when hidden under fresh snow, or it can be so uneven it’s impossible to walk on. Either is the bane of dog walkers during a Canadian winter. As they say in Toronto, “Be nice, clear your ice!”

One of the things that I try to consider is what will happen to meltwater when a warmer spell comes along. If there is a snow bank stopping water from flowing away it will become a puddle and then ice. Our section of road, because it’s on a bend, typically doesn’t get cleared of snow right up to the curb, and so any water that comes down our driveway would puddle on the road because there is nowhere for it to go. So now, while the snow is still soft, I dig a channel along the curb on the downhill side of our driveway, so the water doesn’t form a skating rink. I also ensure the catch basin on the uphill side is open, so water running downhill doesn’t reach our driveway.  

So that’s the measure of my 46 years of snow clearing experience. Clear before the snow gets trampled by people or cars, and clear often. Think where you want the snow to go and then push it there – once. Lift the snow as little as possible, or use a thrower. Never assume the snow is going to melt before it gets to be a bother, but do plan for where the water will go when it does melt.

Because so far, it always has melted – eventually.

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