Monday, March 13, 2017

How to ACTUALLY drive in the snow

After the last couple of weeks of how not to drive in the snow, this week a short primer on what you should be doing. This is true for snow, ice and wet weather, but also holds true for dry roads.
It's simple: let your tyres do one thing at once and you'll be fine.
Brake in a straight line, then let off the brakes and corner, then as you're leaving the corner, begin to accelerate.
This doesn't seem too complicated but I'd wager 95% of drivers don't understand this. You see if you brake and turn at the same time, you're asking the tyres to do two things instead of one. The forces on the contact patch become divided between the braking force and the cornering force, and both become compromised. You can't brake as efficiently and you can't turn as efficiently.
The same is true for accelerating out of a corner - if you plant the right pedal half way through the corner, again you've compromised the tyre's ability to do its job.
This is why ABS anti-lock brakes exist. In the good old days, people would lock up the brakes and try to steer. Once the wheels have locked, the tyres are compromised and they're not even gripping properly for braking. Turning the wheel does nothing at this point. ABS prevents that by allowing the wheels to keep turning meaning more of a chance of the braking force being able to slow you down and more of a chance of a cornering force allowing you to turn. It's compromised because you're braking and turning at the same time, but it's better than nothing.
This whole principle is why - if you start to get out of control in a corner - any corner in any condition - the last thing you should do is touch the brakes. Once a car starts to skid, the contact patch has been compromised and if you hit the brakes, you're going to destroy any last chance of the tyre gripping. Take your foot off the throttle gently and steer into the skid until you feel grip again. ONLY once you have grip should you be using the brakes.
So to snow, ice and wet weather : when you come to a corner, brake in a straight line. If it's snowing or icy you should have snow tyres on which means you'll be able to control your car slowing down in a straight line. Once you're down to a decent speed, let off the brakes and turn into the corner smoothly. If you've done it right, there will be no side-slip and no drama.
Driving in snow is not inherently dangerous - it's drivers who don't know what they're doing that make it dangerous. Drivers with summer tyres, bald tyres, drivers who are texting, reading, eating, screaming at their kids. If driving in snow was somehow dangerous and accident-ridden, then countries like Sweden, Norway and Greenland would have the highest accident rates in the world. But because they train their drivers to drive in the snow, they actually have some of the lowest accident rates in the world - much lower than the US for example. Using road fatalities per 100,000 head of population, the average annual rate for those countries is Sweden (2.8), Norway (3.8), Greenland (3.5) and America (10.6). Driving in snow is NOT dangerous if you know what you're doing.


Markus Dahmann said...

Well - the low accident rate may be linked to a significantly lower traffic density (especially in Greenland ...) than in continental US. Sweden and Norway have strictly enforced speed limits (Norway normally 80 km/h (50 mph) with rare exceptions of 100 km/h (62 mph). Fines are ridiculously high and may reach several thousands of dollars for going more than 20 km/h faster than allowed.

I cannot verify the logical connection to the ability to drive in the snow.

Paul said...

Another thing to add, and it's something I'm surprised you didn't mention Chris, is to drive to the conditions. If it's snowing/icy/wet slow down.