Winter weather hazards for drivers: GEM explains what makes them dangerous

We are encouraging motorists to ensure they – and their vehicles – are ready for the potential challenges of driving in winter. 

GEM Chief Executive Neil Worth has compiled a comprehensive line-up of common questions and answers relating to driving in heavy rain, snow, fog and ice: 

RAIN 

What are some simple tips for staying out of trouble when the roads are wet? 

Reduce your speed and leave bigger gaps between your car and the vehicle in front. Stopping distances increase on wet roads, so give yourself time and space to stop safely. Use your dipped headlights to ensure other drivers can see you. Avoid using rear fog lights as their strength can dazzle drivers following you – and if your fog lights are on, it can make it harder for others to see your brake lights. 

What’s the maximum depth of water I can drive through safely? 

Driving through any depth of water can be dangerous. Even just six inches – or 15cm of water – will reach the bottom of most passenger cars. Above this depth you can lose control or stall the engine because water can be sucked into the exhaust or washed into the air intake. 

SNOW 

What is a safe speed for driving in snow? 

Experience shows that it is not your speed that’s the problem, it’s how you lose the speed in order to stop in an emergency, or to negotiate a sharp bend, or pull up safely at a junction. If there is snow on the road, your braking distance will be vastly increased compared to what you’re used to on a dry road. Be sure to maintain a risk assessment. If it’s actually snowing and settling, then you must slow right down. Try to maintain momentum by anticipating when you’ll need to slow down and speed up. 

What are the best roads to use when it’s snowing? 

It may sound unhelpful, but the best advice is not to drive at all if you don’t need to. Gentle hills can become impassable, and even busy motorways can quickly turn into car parks during a snowfall. 

 What emergency equipment should I take if I have to drive in snow? 

Take a hot drink flask, snacks, a blanket, rug or sleeping bag to ensure you can stay warm if you get stuck. If you need to leave your vehicle, then it’s a good idea to ensure you have boots, a warm coat and reflective jacket with you. 

BLACK ICE 

What is ‘black’ ice? 

Black ice is actually clear and colourless ice, but it is invisble to drivers above the dark tarmac of the road. 

 How will I know if I’m driving on black ice? 

Your steering will feel light, you won’t see tyre tracks on the road ahead, and there will be next to no noise from your tyres. Stay calm and let your car pass over the black ice. Gently lift your foot off the accelerator. Don’t hit the brakes and be very gentle with your steering. 

If I can’t see it, how can I look out for black ice?

Pay attention to your car thermometer. Black ice forms when the road surface temperature falls to 0 degrees Celsius or below. But road surface temperature is usually three to four degrees lower than air temperature. That’s why you may get an audible cold weather warning when your car thermometer shows 3 or 4 degrees. 

When and in what locations is black ice most likely to form?

The most likely times for the forming of black ice are around dawn and in the late evening, when temperatures are usually at their lowest. The most common locations for black ice are shaded or tree-covered parts of roads, due to the lack of sunlight. Bridges freeze quickly so be particularly careful. 

FOG 

What is fog? 

Fog is a thick wet mist that either rolls in from the sea or radiates up from the ground. Fog forms when the temperature drops to the point at which air is saturated, and invisible water vapour in the air condenses to form suspended water droplets. It’s dangerous for drivers because we can see so little. So you need to go slowly, and use dipped headlights and fog lights. 

Is there anything I can do to continue driving safely when the fog is really thick? 

Possibly not. You can wind down the window, in an attempt to hear what you may not be able to see, but there’s no magic way for gaining visibility. 

Should I use the rear lights of the vehicle in front or the centre white line of the road as reference points? 

No. It’s dangerous to follow the lights of the vehicle in front as you may well allow yourself to get too close, meaning you might not have enough space to stop suddenly. You can follow the edge of the road as a reference point, rather than the centre, to avoid running into oncoming traffic or becoming distracted by their headlights. 

Read our related blogs:

Top 5 tips to avoid a winter breakdown

Planning for safer winter journeys

Storing petrol over winter

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