Fog represents a major challenge for French motorists, particularly during the winter period. Although rain and snow often attract the attention of drivers, fog remains an underestimated danger which nevertheless requires increased vigilance and specific driving techniques. Indeed, this air mass saturated with water considerably reduces visibility and modifies our perception of the environment. A dangerous cocktail that requires immediate adaptation of our driving behavior.
The misleading effects of fog on our perception
Fog doesn’t just reduce our field of vision. It causes several optical effects that significantly disrupt our ability to judge distances and spot obstacles. The halo effect turns light sources into blurry spheres that are difficult to interpret. Road signs and traffic lights are becoming less distinct, making it more difficult to read information essential to our safety.
Even more insidious, the phenomenon of extinction literally causes certain elements of our environment to disappear. A black vehicle without lighting can thus become completely invisible, even at short distances. This alteration of perception considerably increases the time required to identify and react to a potential danger.
Fog also changes our sense of speed. Usual visual cues fade, creating a deceptive impression of slowing down. This illusion naturally pushes drivers to speed up to regain their usual sensations. A dangerous reflex which explains many accidents.
Lighting, an essential element of driving in fog
The appropriate use of different lighting systems becomes essential in foggy weather. Low beam headlights constitute the essential basis for signaling your presence to other users, even in broad daylight.. Contrary to popular belief, high beams (or full headlights) prove counterproductive : their powerful beam reflects off suspended droplets, creating a white wall that further reduces visibility.
The front fog lights provide valuable additional lighting. Placed low on the vehicle, they pass through the fog more effectively and improve the visibility of road markings. Their simultaneous use with the low beam optimizes the detection of nearby obstacles.
The rear fog lights deserve special attention. Their high intensity certainly allows them to be spotted from afar, but can also dazzle the drivers behind them. They should only be activated when visibility falls below 50 meters, and deactivated as soon as conditions improve or a vehicle approaches.
How to adapt your driving in fog?
Reducing speed is the first and most important safety measure. Regulations impose a limit of 50 km/h when visibility falls below 50 meters. This restriction applies to the entire road network, including on highways. Beyond the legal aspect, this speed reduction makes it possible to maintain a stopping distance compatible with our reduced field of vision.
Maintaining safe distances becomes crucial in fog. The temptation to follow the taillights of the vehicle in front creates a dangerous vacuum effect. The drivers gradually move closer to each other, forming a train of vehicles that is particularly vulnerable to the slightest slowdown. It then becomes vital to resist this natural attraction by maintaining a sufficient distance otherwise it will create a multiple collision chain.
Positioning on the roadway also requires special attention. Systematic use of the right lane allows you to maintain a stable reference point with the side markings. Overtaking, which is particularly risky in reduced visibility, must be avoided. Prudence also requires increased vigilance when approaching areas prone to fog and ideally avoiding them, like fields, valleys, watercourses and other wooded areas. Of course, the ideal is to postpone your non-essential journeys until a more suitable time, when the fog has lessened in intensity.
- Systematically reduce your speed and maintain increased safety distances
- Use your low beam and fog lights appropriately depending on the conditions
- Postpone your unnecessary journeys while waiting for better weather conditions
