Seeing and being seen are crucial for safety
Do not rely on automatic light control in fog
The automatic light control in modern cars takes a lot of work off the hands of drivers: It automatically switches on the low-beam headlights when it gets dark or when you drive into an underground car park or through a tunnel. However, in fog and other diffuse light conditions, the automatic system often does not work perfectly: DEKRA experts advise drivers to think for themselves and switch on the low beam manually.
- Some situations require switching on the low beam manually
- When the daytime running lights are on, the rear lights remain off
- In poor visibility, adjust your speed and keep your distance
“Automatic headlights have significantly improved safety. However, you should not rely on the technology blindly”, says Denis Preissner, accident researcher at DEKRA. ”The light sensors in many vehicles only distinguish between light and dark and, in fog, drizzle or spray, usually only switch on the daytime running lights, but not the low beam. The sensors in the latest vehicles are becoming increasingly sensitive, but it is still important to stay alert and pay attention to the lighting settings.”
Daytime running lights are not enough in poor visibility
In daytime running light mode, the headlights are dimmer and the rear lights are switched off completely. This makes the vehicle much more difficult to see from the front and rear, and critical situations can arise more easily.
In such situations, when there is poor visibility, drivers must therefore reach for the light switch themselves and activate the low-beam headlights. “The earlier, the better”, says Preissner.
Visibility in diffuse light usually improves when the fog lights are switched on. These emit light more broadly than normal dipped headlights and illuminate the road better at close range.
“When driving in fog in the dark, we recommend switching on fog lights, if available, in addition to the low beam to get optimal visibility and illumination of the road”, says Preissner. ”High beam, on the other hand, makes little sense in fog or snow. It is strongly reflected by the fog droplets or snowflakes and thus worsens visibility due to glare.”
When visibility is below 50 meters (~165 ft), it is recommended to switch on the rear fog light to ensure greater safety. Even in dense fog, your own vehicle can be recognized earlier by the following traffic thanks to the bright rear light. However, you should also drive slowly; some countries limit speeds at 50 km/h (~31 mph) when the rear fog light is switched on. When the fog lifts, the bright light must be switched off again so as not to blind following road users.
“Don't forget the most important rules for driving in fog”, emphasizes accident researcher Preissner. ”They are: adapt your speed, keep your distance and never closely follow vehicles driving fast in front of you. Otherwise, there is a risk of the typical mass accidents in fog.” Those can only be avoided if you can stop at any time within the visible distance. On lanes that are so narrow that oncoming vehicles could be endangered, you should be able to stop within half the visible distance.