Driving in winter offers a plethora of challenges for motorists. Driving in fog in particular represents one of the most dangerous conditions that any driver faces. Fog is simply a low-lying cloud comprising of water vapour that is sourced from a moist ground.
If the temperature is freezing, fog vapour can turn into ice particles. Fog often causes a significant reduction in visibility and is exacerbated whilst driving at night due to a vehicles lights reflecting back from the water vapour or ice particles onto the driver.
This guide offer advice for preparing to drive in fog, how to drive in fog safely and fog lights law.
When to turn on fog lights
Fog lights can be used for other weather conditions other than fog. Generally, anything that limits your visibility to 100 metres, or about the length of a football pitch, using your fog lights may provide you with better visibility, but more importantly, to allow other motorists to see you easier. Other conditions may include heavy rain and the spray caused by other vehicles.
Driving in fog preparation
If faced with fog, it is of course best to avoid driving at all. That’s not always possible however, so a little preparation before setting out into one of the most dangerous driving conditions should help to keep you as safe as possible.
General preparation for driving a vehicle in fog is to:
- Ensure all car lights are in working order and are clean (not forgetting to check fog light(s)
- Check all windows are clean both inside and out so to ensure visibility isn’t further reduced by other factors
- Check window washer reservoir and fill up with fluid if necessary. The use of windscreen wipers is frequent whilst driving in fog and if your vehicle is receiving dirt and spray from other vehicles, you will need plenty of windscreen washer fluid
- Ensure tyres have the correct pressure. Driving in fog can often require heavy braking and if tyres are either under inflated or over inflated, grip and stopping distances can be significantly affected – especially if conditions are icy
- Familiarise yourself with the operation of your fog lights to ensure you know how to turn them on and off
Driving in fog
Now comes the challenging part, driving in fog. Let’s take a look at some top tips for driving in fog.
We all take driving for granted and we all let our concentration slip from time-to-time. A lack of concentration or not paying attention is dangerous in the best of conditions. The trouble with fog, is it’s unpredictable. It can be reasonably clear one moment and as soon as you feel it is safe to increase a little in speed, you can immediately hit a dense patch of fog. Concentrate and be prepared for conditions to change almost instantly.
Use dipped headlights only. Unlike fog lights that attempt to illuminate the road underneath the fog, main beam headlights direct bright light into the fog itself, reflecting the light back to the driver and further reducing visibility. Light reflected back to the driver can be exacerbated in low temperatures if fog water particles turns to ice.
Following another motorist closely in fog provides a false sense of security. The necessity to dramatically reduce speed in fog when faced with dense fog patches and other hazards can be frequent. Tailgating a vehicle in front reduces your thinking and braking distance if they should need to slow down or stop abruptly. The 2 second rule is an easy to follow method for a safe following distance in good weather.
In adverse weather conditions, the 2 second rule should be extended to 3 seconds, or 4 seconds in icy and significantly reduced visibility conditions. If a driver is tailgating you, don’t be tempted to speed up. If you need to abruptly reduce speed, the driver behind may need more time to react to your actions.
If you are being tailgated, you may need to further increase the distance from you and the car in front, allowing you more time to slow down and in turn, providing the driver behind with more time to react. See tailgating for further information on the dangers, laws and penalties for tailgating.
4. Motorways and dual carriageways
It can be tempting to increase speed on motorways and dual carriageways as they are often wide and relatively straight. Be cautious of dense fog banks that you may enter as there could already be traffic inside traveling at a reduced speed.
Be highly cautious pulling out at junctions. It can be difficult to see oncoming traffic. If in doubt, opening your window and listening for vehicles may assist.
If pulling over to take a break or parking up at a destination, remember that motorists may struggle to see your vehicle. Ideally find a safe parking area off of the road or if this is not an option, keep sidelights or parking lights illuminated.
Fog lights law
It is a legal requirement to have at minimum a single tail end fog light fitted and in working condition, installed either at the centre tail-end or drivers side. All modern European cars have at least the minimum legal requirement fitted as standard, although some models have front fog lights fitted also.
Although to remain within the law a rear fog light must be fitted, you are under no obligation to actually use them – even if it’s foggy. In fact, you’re more likely to find yourself in trouble by using them inappropriately. If the weather clears up and you forget to turn off your fog lights, you may find yourself being ushered to the side of the road and being either issued with a warning, or even a Fixed Penalty Notice (FPN) which comes with a fine of £30.
This type of FPN is non-endorsable and does not issue penalty points to your licence. It is of course better to use them rather than being afraid that you may forget to turn them off. After all, safety is priority.