How (NOT) to Drive on Ice
This article is not intended to be a tutorial on how to drive – I just felt the need to point out some things that some people may not know. I am not a professional driver. I am not a driving instructor. But I do know a thing or two about racing. Vehicle dynamics is based on physics and therefore can be felt if one is listening and not frozen in fear. I have seen too much dangerous driving leading me to believe that people are not intentionally driving wrecklessly — this simply don’t know because they can’t feel what is going on! These tips are based on tried & true racing principles wrapped in common sense. When foul weather rolls in, do you tense up in fear rather than grinning ear to ear in anticipation? If so, this article is for you…
Get equipped
Do you drive a car with front-wheel drive (FWD), rear-wheel drive (RWD), four-wheel drive (4WD) or all-wheel drive (AWD)? If you drive an SUV with 4WD, do you know how to engage the other axle, how to disable the traction control or lock the differential? Do you know if your car distributes power primarily to the front wheels (until slippage is detected), or evenly split between axles? Dig out that owner’s manual! You need to understand in order to predict what will happen when you apply the gas. There is even a difference in how your car will react if it is AWD rather than 4WD but if you are coasting, it doesn’t really matter! RWD pickup trucks – beware!
Where the rubber hits the road
Your choice in tires (and their pressures) is perhaps the biggest factor in whether you can control your vehicle in snow, ice, rain or mud. Do you have summer tires, all-season, mud & snow or winter tires? Are they studded? The amount of traction available is directly linked to the type of tires you have mounted and tire compound in addition to the tread pattern is very important in freezing conditions. Every 10° Fahrenheit change in ambient temperature leads to a 1psi change in tire pressure so checking pressures is critical. Why does tire pressure matter? Well, have someone squash a balloon against your windscreen as you sit in the driver’s seat and you will start to understand contact patch.
What causes a slide?
You slide when you exceed the limits of adhesion between your tires and the road. Grip or adhesion is a consequence of friction:
Fmax= coefficient of friction × weight on wheel
Once you break the coefficient of friction, you will be sliding. Not all slides are bad – racers often induce a slide to “finish the corner”…but don’t worry about this until you’ve won some trophies. You can break the coefficient of friction through any abrupt change – acceleration (stomping on the gas), deceleration (braking or letting up on the throttle suddenly), change in direction (turning quickly). A good rule of thumb to follow is never do anything abruptly — smooth is fast! Practice being smooth with all your controls. When you move your foot from the gas pedal to the brake pedal, try not to lift your entire foot but instead flex your ankle. The reason why F1 drivers use their left foot for braking and their right foot for the throttle (in addition to limited space in the footwell) is because transitions between acceleration and deceleration are much smoother. Brake application should start with light pressure in order to transfer the weight and plant the front tires before heavy braking. The same goes for throttle application (think 1–5% initial pressure before exponentially rising). For steering, it pays to be proactive with the eyes by looking through the vanishing point and connecting the dots from entrance to exit choosing the best line through each corner. What is the ideal line? The one that requires less turning! It also depends on many other things such as corner radius (how tight it is), whether the road goes uphill or downhill (creating weight bias) and if there is any camber (banked or positive camber is safer than negative camber). A long sweeping turn may actually be more dangerous than a sharp turn where you have to slow down a lot before turning because you are turning for less time.
Be aware!
Awareness is your safety net. I’m not just talking about texting while driving. I’m talking about how your eyes see both foreground and background along with your peripheral vision. In addition, your ears and seat-of-the-pants feel also provide information. Is the car behaving the way you expect? If not, figure out why! You should be scanning with your eyes the entire time to avoid target fixation – you WILL hit what you are staring at! Look for differences in traction on the road – bare pavement or crunchy snow may have more grip than translucent packed snow while tire tracks are often more slippery due to freeze/thaw forming black ice.
What is the worst thing you can do?
Grip the wheel tightly with rigid arms and stabbing at the brakes! That is a recipe for disaster on ice, in the rain, or on gravel. Sometimes you may even want to MORE gas to counteract a spin! The key thing is to pay attention to Direction – where the car is pointed regardless of the wheels. If you are slowed & pointed in the proper direction (not off the road or into oncoming traffic), you can safely apply the gas, but not before you are done turning. Maximum braking can only be achieved when pointed straight ahead because grip is shared between driving and turning. If you begin to slide after applying the brakes, simply ease off the pedal slightly so that the wheels begin to roll again which will help regain traction. Also note that ABS does not work very well at very slow speeds!
If even one person avoids an accident this winter, this article would have served its purpose.
