Lái xe trong mưa mù - Những lời khuyên an toàn

s we enter the new year, our winter weather becomes less of a novelty and more of a constant low-level hazard. Black ice forms, snow settles, and fog comes rolling in.

Even if you’re a confident driver, fog can make driving difficult and dangerous. And if you’re not, driving in such reduced visibility can be a deeply unnerving prospect. The Met Office has issued warnings following a fatal crash on the A40 and motorists are being advised to take extra care – fog is a dangerous weather condition that is a contributing factor in accidents every year.

Fortunately, if you follow a few simple rules, and are patient, sensible and cautious, you can minimise the chances of having an accident. Of course, you can’t mitigate for the other drivers out there – but the more of us that make allowances for the conditions, the safer the roads will be.  

So even if you’re pretty happy that you can handle the risks involved in driving in fog, it’s worth reading through for a refresher. And if you aren't, hopefully these tips will help you to better understand how to stay safe in mist and murk.

Drive only if it’s necessary

Yes, you’ve heard it on the weather forecast plenty of times, but people say it for a reason. Put simply, if you don’t go out, you can’t come to any harm on the road. Is your journey really that urgent or important?

If not, it might be better to stay in, have a cup of tea, and wait until the visibility improves. We’ll wager you’d rather that, than get stuck in a queue or, worse, at the side of the road in freezing fog.

Check your headlights – and then use them correctly

If you do decide to venture out, then before you leave, you should try and make a quick check of your lights. Turn on your dipped beams and check the lights are working on both sides, at the front and at the back.

When conditions do start to get foggier, you should turn your headlights on. Don’t just assume they already are – many cars’ dials light up even when the headlights are turned off these days, which can be misleading.

Rather than relying on these lights, you should check the position of your headlamp switch and make sure it is set to the dipped beam setting. This will improve your vision, and enable other drivers to see you in good time.

If you have automatic headlamps, make sure these have activated – or better still, override them manually by turning the headlamp switch to the dipped beam setting.

Many drivers assume that foggy conditions mean you have to use the brightest lights you can. That, though, is entirely the wrong thing to do. You should always avoid using full beam (also known as main beam) headlamps in fog, even when there’s nobody else around, because the fog actually reflects the light back at you, and that has the effect of reducing, rather than improving, your visibility. If the little blue headlamp light is glowing on your dashboard, you need to turn your full beams off. 

Use your fog lights – but only if the fog is thick enough

All cars come with rear fog lamps – it’s a legal requirement – so yours does have them fitted. Do you know how to turn them on and off? If not, make sure you find out at the earliest possible opportunity. You don’t want to be scrabbling around trying to find a switch just as the fog thickens up.

Remember that they will only work with the headlights turned on, so make sure you do that first.

Don’t turn your rear fog lights on any earlier than you need to, either, or you could be dazzling the drivers behind you. The Highway Code says that you should only use your fog lamps when the visibility drops below 100m.

If you’re not sure when that is, a good rule of thumb is to work out whether you can see the tail lights of the car in front of you. If you can’t, you (and they) should probably be using rear fog lamps. However, if you can, you probably don’t need them.

Some cars also come with front fog lamps, which throw out a low, wide beam which cuts below the fog to help you see where the edges of the road are. They are not actually necessary to use unless the fog is extremely thick, as the advantage they provide in terms of visibility is marginal, but if you do want to use them, the same rules apply as to rear fog lamps.  

You can tell when your rear fog lamps are on because an orange lamp-shaped symbol, with horizontal straight lines intersected by one wavy line, will light up somewhere on the dashboard. Likewise, front fog lamps are indicated by a green lamp-shaped symbol with sloping straight lines and a wavy line.

Don’t forget that when the fog clears, you’ll need to turn your fog lights off again as soon as possible, otherwise you’ll dazzle the people behind and in front of you. And remember that in patchy fog, you should turn your fog lights off in the clearer patches, and on again when the fog gets thicker.

If you’re in any doubt about which lights to use, put yourself in the position of other drivers around you. Ask yourself what your car looks like to them, whether they can see you, and whether they might be blinded by any of your lights.  

Turn on your heater

Fog outside will often cause condensation inside – and in foggy conditions, that condensation can form without you noticing. We’ve even heard reports of drivers reaching their destination, and being surprised upon leaving the car that it’s sunny outside.

Most modern cars have good heaters, but a good heater is only as effective as the person operating it, so make sure you understand how your heater works – particularly the windscreen de-misting function.

This is normally a button, switch or setting on a dial that shows a screen with a curved top and bottom with wavy arrows pointing up at it.

You should also turn on your heated rear window – this is normally symobolised by a rectangle with wavy arrows pointing up at it.

Some modern cars have heated front windscreens, which can demist the screen very rapidly and should be used whenever there is condensation in the car. These are normally indicated by a curved screen symbol, but this time with a zig-zag line drawn across it.

Use your ears

This might sound daft, but it’s a sensible technique few people think of when it’s foggy. Turn your music off and wind your windows down at junctions – that way, you can listen for oncoming cars when you can’t see them.

Keep your music turned off on the motorway, too – it’ll help with your concentration, and you might hear the hiss of tyres of a car overtaking you that you haven’t seen.

Keep your distance

Keeping a sensible amount of space between your car and the car in front should be obvious when visibility drops, but fog has been a key factor in some of the largest and most infamous pile-ups on Britain’s roads, and it didn’t cause them. What caused them was drivers following each other too closely to be able to react when things went wrong.

You might think you’ve left enough room to stop if the car in front of you brakes. But what if the car in front of you is also following too closely? If they smash into the car in front of them, it’ll bring them to a sudden stop, far more rapidly than you’re expecting. In that case, you’ll have far less time to react.

That’s why it’s advisable to leave enough of a gap to the car in front that you can come to a halt safely if they stop suddenly. If that means backing off to a point where you can no longer see that car’s lights, it’s safer to do so than to creep ever closer in order to stay in contact.And if another driver is following you too closely, don’t be tempted to react. It’s easier and more sensible to concentrate on your own driving, perhaps pulling over to let them go on their merry way if you’re able to, than to do something provocative that might cause them to crash into you. 

Slow down

Again, this might sound obvious – but many people lose perception of their road speed when their surroundings are blotted out. As a result, people who aren’t paying attention sometimes end up driving even faster in the fog than they would with clear visibility.

People often drive too fast in the fog if they think there isn’t a car in front of them. However, the very problem with this logic is that the fog can hide a multitude of things – including a car that’s just beyond the limit of visibility.

That car could be driving much more slowly, or even stopped. It might not even have its lights on. And it goes without saying that parked cars stopped at the side of the road can loom out of the murk frighteningly quickly.

The only way to guard against all of these factors is to drop your speed. Use the objects you can see, such as signs at the side of the road, to get an idea of how close or far away the limit of visibility is. Then drive slowly enough that you’ll be able to stop if a stationary car appears in front of you at that distance.

Remember the road conditions

One thing people often forget about fog is that it coats everything with a damp, moist layer, in much the same way as light rain does. That includes the road surface, so it makes sense to take that into account when you’re driving.

It doesn’t help that fog blanks out people’s vision of the road surface up ahead, so the fact that the road is wet isn’t as obvious. This effect is even worse at night time, dusk or sunset.

What’s more, if it’s cold enough, the moist layer will turn to ice, which can make driving conditions even more hazardous.

So if it’s foggy, remember the effect that will have on the road surface, and drive accordingly.
Theo Alex Robins