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Road safety: How to drive in snow

How far north you are (in the northern hemisphere) tends to influence how severe your winters will be and, therefore, what precautions you need to take when driving. Remember, good drivers anticipate what could happen and adjust accordingly; average drivers only react to what is happening. As we’re coming into winter, now’s the time to start thinking about driving on snow.

If you are new to driving, it’s best to practice driving in snow during the day before you drive at night. There will be less chance of ice and frost on the road, and it’s easier to spot potential hazards.

Vehicle condition

In extreme temperatures your engine and the fuel in it can freeze. Keep your fuel reasonably well topped up in case you get stranded and need to keep the engine running to stay warm.

Ensure your fluids are topped up and you are using antifreeze. You can try some vehicle maintenance and safety questions from the Highway Code here.

If you notice your brakes pull to one side, this will be dangerous when it’s slippery because it could cause you to spin.

Tyres

Special snow tyres are available if you regularly experience prolonged snowfall, as well as snow chains for more extreme conditions. Check the tyre pressures regularly. Cold weather will reduce the pressure by about 1psi (pound per square inch) for every 5 degrees Celsius or 9 degrees Fahrenheit. While this technically means that more of the tyre is in contact with the road (which theoretically means more grip), if it’s too low, it will negatively affect the vehicle’s handling.

If your vehicle pulls to one direction under normal driving, or if you get a vibration at certain speeds, you need your wheels balancing and aligning.

Windscreen, windows and mirrors

If your windscreen is frozen, don’t pour hot water on it as the sudden temperature change can cause it to crack. Instead, pour cold water on as this will still be enough to melt the ice, which you can then scrape off. If possible, cover your windscreen overnight to make clearing it quicker and easier.

Ensure that your rear demister and front windscreen heaters are in good working order as the temperature differential from inside to outside can cause your windows to fog up extremely quickly. Use your air conditioning to speed up the process.

Your windscreen should also be kept clean otherwise sun dazzle (sun strike) will be much worse.

Your external mirrors and lights may also ice over. Some vehicles have heated external mirrors.

It’s best to warm up the vehicle before you drive away so that you can keep the windscreens clear.

What to carry

At minimum you should carry a shovel for digging yourself out, a windscreen de-icer/scraper, snow chains for extra grip, some warm clothes (including gloves), some drinking water (because melting snow isn’t convenient) and muesli bars in case you get stranded, sunglasses to combat the glare from snow and sun strike, and a tool kit.

Ideally, you will also want to carry the following:

  • Bag of sand or salt to help with grip and defrosting ice
  • Brush
  • Booster cables
  • Blanket
  • Extra windscreen fluids
  • Torch
  • Traction mats
  • Fuel line de-icer (methanol, methyl hydrate or methyl alcohol)
  • Something bright to attract attention
  • Maps.

Winter driving hazards

The low position of the sun makes sun strike more of a problem in winter. This is where the sun is in your eyes and it hampers your vision. Sun strike is far worse with a dirty windscreen, and you will be temporarily blinded if you use your windscreen washers to clear the windscreen, until it’s cleared.

When the sun isn’t blinding you, it can often not provide enough light. Headlights are essential, often even during the middle of the day.

Ice and compacted snow make it treacherous as the coefficient of friction is significantly less, therefore you are more likely to slide off the road. It’s recommended that you stay 10 seconds behind the vehicle in front in icy conditions. Most new cars have traction control and various electronics such as Electronic Stability Programme, VSC, anti-lock brakes (ABS) and more. These electronics monitor how your car is performing on the surface and will intervene with braking, power delivery and even steering assistance if they detect the car is travelling sideways rather than forwards. Newer heavy vehicles and passenger vehicles also come with some of these electronics.

However, electronics can sometimes be confused by very slippery conditions, and traction control is sometimes ineffective where there is very little traction at all, therefore there’s always a button to turn it off. Similarly, ABS can be a disadvantage in really icy conditions. If you are in a large vehicle such as a bus, if you are on a downhill slope and there is not enough friction to stop you sliding, regardless of ABS or not, you will start to slide (you can see this in the video at the end of this story).

Snow banks and drifts can make it difficult to see the edge of the road. Snow may even drift across a road before there’s a chance for it to be cleared.

Fog and freezing fog cause visibility problems as they reflect the light back from your headlights.

Check out vehicle handling questions in the Highway Code by clicking here.

Driving

Using a higher gear will reduce your chances of wheelspin as the revs won’t climb as quickly, and therefore the effect of torque overpowering the grip will be much reduced.

When you brake be much more gentle and try to use engine braking as much as you can. This means slowing down for corners and junctions early.

When you are following another vehicle, double your distance to at least four seconds to account for the increased slipperiness of the road.

Dip your lights. You’ll see better with dipped lights than full beam if it’s foggy or snowing.

If you are driving a front-wheel drive vehicle you are more likely to experience understeer (where the vehicle wants to continue straight ahead) on a slippery road when accelerating. If you are driving a rear-wheel drive vehicle, you might initially experience understeer when accelerating, but if the rear wheels break traction, it can turn into oversteer where the rear of the vehicle snaps sideways. If you are driving a four-wheel drive vehicle, you might get understeer or mild oversteer, but you are probably more likely to experience what’s called four-wheel drift where the vehicle slides sideways fairly uniformly.

Different road surfaces will react differently in cold weather. Smooth concrete bridges will become icier and more slippery quicker than rough roads that have the insulating factor of the ground underneath them.

Busier roads are more likely to have been gritted, and will have greater traffic flow to help if you strike trouble.

Safety

If the weather is particularly nasty, let someone know where you are going and have them check in with you. Allow more time than usually to get to your destination as there may be detours. Check weather forecasts before you travel and only go if you absolutely must.

If you do get stuck, keep a window slightly open and keep the engine running with the heater going to keep warm. If you can, tie something visible to the aerial so that rescue services know you are in the car and will be more likely to see it even if the snow drifts are high. Remove it if you leave the car. However, unless your vehicle is in danger of being hit by another vehicle, it’s often best not to leave it as it provides shelter, especially if you are in blizzard conditions. If you can see help within 50-100m, then leave the vehicle, but keep well away from the flow of traffic (if there is any) because other vehicles might lose control, too.

If there are two of you in the vehicle, share the blanket and huddle together for warmth. Monitor each other for signs of hypothermia and frostbite. One person should stay awake at all times. Don’t stay in the same position for too long – move around, clap your hands, use body resistance to create weight you can pull or lift against to keep your blood flowing.

Don’t keep the radio on as you might miss rescuers’ calls. If your cellphone works, let people know where you are and that you are staying there until the blizzard clears.

If you want to see just how slippery snow and ice can be, have a look at this video filmed on a hill somewhere in Utah. Start from about one minute in, and watch for the totally out of control car at 2:15.

Darren has owned several companies in the automotive, advertising and education industries. He has run driving theory educational websites since 2010.

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Posted in Advice, Car, Heavy Vehicle, Passenger Vehicle

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