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Road salt vs. gravel

It has been mild and wet in Toronto over the last week, but normally at this time of the year, the entire city looks like as if it was just hit by some sort of apocalyptic chalk storm. Everything is white. And that’s because we rely on rock salt and liquid salt brine to keep our roads and sidewalks free of snow and ice. Each winter, the city uses upwards of 130,000 tones of salt to maintain its service levels.

This is the tool of choice because it is both reasonably effective and cheap. However, the trade-off is that it does horrible things to the environment. It also ruins perfectly good shoes, which should tell you something about what it’s doing to the environment. So it’s a balancing act: Yeah, it’s terrible for the environment, but we want usable roads and sidewalks. People slipping and falling is also a liability problem.

That said, when I was in Montreal over the weekend, I did notice a greater use of gravel:

This causes its own set of problems in the spring when it all needs to be tidied up. But in the interim, it did allow me to wear my neon Nike Air Max 90s without the fear of them disintegrating on my feet. Sometimes there’s also no choice. Road salts only work down to a certain temperature and then they become ineffective. So there are lots of examples of cities using sand and/or gravel to improve traction.

This is not the case in Toronto. We rely on rock salt. And part of the reason for this is that our winter service levels dictate “bare pavement” on highways and arterial roads. Gravel doesn’t get you bare pavement. Salt does. Also, Ontario doesn’t require snow tires, whereas Quebec does. So there is an argument that, because of this, we are all ill-equipped to deal with anything besides bare streets. (Though have you seen our sidewalks and bike lanes?)

I am not a salt management expert. I opted out of that fascinating elective in University. But in my opinion, the goal should be to use as little rock salt as possible. Maybe that means we need to rethink our service levels and our priorities. And maybe that means we need to do things like mandate winter tires.

9 Comments

  1. Tom

    Not to mention its super corrosive to concrete and rebar. Shorter lifespan for concrete; more repairs, more concrete poured, more embodied carbon, more environmental impact, etc.

    Also once saw an environmental report where the heavy metals in road salt actually led to exceedances in the soil and almost couldn’t get the Eng. to sign off on a clean Enviro report…..

    My understanding is it’s a great business though (few suppliers, huge demand). Cost of road salt is also crazy, it’s surprisingly big OpEx line item for properties with lots of landscaping.

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  2. Siobhan

    Appreciate you writing about this very important topic! Couldn’t agree more with your assessment of things. I am very pro mandating winter tires for a certain time period, and using more gravel/sand and far far less rock salt!

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  3. Ben Wedge

    Regardless of the debate between gravel and salt, we use too much salt. If you can see it on the ground, too much was applied. Vermont has been doing great work educating contractors and also shielding them from excessive liability claims related to slips & falls. In Canada there is also a “smart about salt” certification program https://smartaboutsalt.wildapricot.org/ We could do a lot better with the existing tools and materials.

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  4. AM

    Perhaps you need to rethink your expectations of wearing pristine sneakers in the winter and do the shoe equivalent of sports cars drivers driving a winter beater. I jest of course.

    When the road is bone dry and and almost white, it doesn’t take a genius to figure out that there is too much salt.

    As someone who grew up in the Alps and know the lifesaving potential of winter tires, I’m always baffled when friends tell me they don’t put on winters on their cars. That is insane to me.

    While I’m normally not a big fans of government telling us what to do, Quebec’s winter tire policy is sensible given our climate.

    Ergo, if all cars had winter tires on, we could live with a little snow on the ground and still be OK.

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  5. Rob Carthy

    Ontario may not have a mandatory snow tire law however our insurance companies require you to either commit to installing winter tires or pay a higher premium. Looking around my middle class neighbour hood there is not a car without winter tires. Have not observed winter tires on police, fire or EMS vehicles. Possibly this why we do not have winter tire legislation, just an insurance requirement which appears to work.

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