How to drive safely through heavy fog

Drivers need to take additional care in thick fog or any other situation when visibility is reduced.

Sometimes fog comes very unexpectedly – the most important thing then is to keep more distance from the car in front, adjust your speed and turn on your lights, says Germany’s ADAC automotive club.

The minimum distance in metres should then correspond to your speed in kilometres per hour. So if you are driving at a speed of 50, a good distance is at least 50 metres from the car in front. And only drive at a speed that allows you to stop within a visible distance.

If visibility is less than 50 metres, the law only allows a maximum speed of 50 km/h in Germany – it makes sense to check the regulations where you are. Only then is the use of rear fog lights permitted – more about this below.

Do not rely on automatic lights

However, you should always switch on your lights in poor visibility. This is also mandatory when visibility is significantly impaired by fog, snowfall or rain. Check your local laws as this may be legally required once visibility on motorways is less than around 150 metres, or on rural roads when it is less than around 100 metres. The limit in built-up areas is around 60 metres.

But even before that, it may be advisable to make yourself more visible by actively switching on your dipped headlights. Modern cars often have daytime running lights that switch on automatically when the ignition is turned on. But sometimes that is not enough. In autumn, visibility is poor even during the day – and then only the lights at the front of the car would be switched on.

Your automatic light system often does not respond to fog, rain or snowfall and does not automatically switch to low beam. So it is better to switch them on yourself if necessary, the ADAC says.

Use fog lights and rear fog lights correctly

However, it is better to avoid using high beam in fog, as this actually worsens visibility. Turn on your normal dipped headlights or fog lights, if your car has them, the ADAC says. These scatter the light very flat across the road and illuminate it better. You can always do this when fog, snowfall or rain significantly impairs visibility. However, you should switch them off again immediately or switch to dipped headlights when visibility improves.

But the situation is completely different with rear fog lights, which every car must have on board. These may only be switched on in foggy conditions and only when visibility is less than 50 metres. They must also be switched off immediately as soon as visibility improves so as not to dazzle drivers behind you.

Depending on where you are, misusing your rear fog lights can involve a fine.