Use of Fog Lights

Do you know the Highway Code guidance around the use of fog lights?

If, upon seeing the first signs of mist in the air, you reach for the button on the dashboard then you may want to dust off your copy of the Highway Code.  According to Rule 226 you "must use headlights when visibility is seriously reduced, generally when you cannot see for more than 100m (328 ft). You may also use front and rear fog lights."  There is no hard and fast rule that states when it is misty/foggy, you should use fog lights - this is left to the driver and is a subjective decision.

These two images, taken at the same location clearly shows the reduced visibility the fog has. Although not thick fog, you can clearly see the cream building ahead in the right hand picture, but not in the left. 

However, having assessed the conditions and decided that fog lights are necessary, there are some definite things which you should do.  Firstly, increase the gap between yourself and the car in front.  Whilst this may seem counter-intuitive - after all, given that visibility has been reduced doesn't it make sense to close in other cars so that you can see them - by increasing the gap between you and the car in front you are giving yourself a safety cushion.  You do not know how observant the other driver is and, if they do not see something and have to react at the last minute, you want time to bring your vehicle to a stop safely whilst also managing the car following you so a multiple pile up is avoided.

Secondly, be aware that driving long distances with limited visibility can be tiring.  You will therefore need to plan more breaks than you might have initially anticipated and allow time for your eyes to recover from the strain you're placing on them.

Remember the Sheppey Crossing incident
last year? 130 vehicle pileup happened
in the fog. But was it solely the fault of
the weather?

Thirdly, do not assume that just because you can see no lights that there is nothing there.  Whilst you have been conscientious and used your fog lights (or dipped headlights if visibility is impaired but not less than 100m), not all road users are as good as you are!  As an ex-driving instructor of mine used to say "treat everyone else as a fool and you'll seldom be disappointed".  Therefore, before proceeding at any junction or hazard, take time to double-check and consider winding down your window to listen for engine noise.  Sound can often carry better in fog and this will give you some early indications that you're not alone!

Finally, once the fog has cleared, remember to turn off your fog lights.

Some top tips:

• When in traffic consider turning off rear fog lights.  They are designed to improve your visibility to other road users and continual exposure at close range may dazzle the driver behind and mask your brake lights (thereby potentially causing a rear end shunt).
• Do not keep turning them on and off when going through patchy fog - make a decision and stick to it.  Flickering lights will be more of a distraction to following cars than the potential dazzle.
• Only use fog lights if visibility is below the recommended 100m and, when they are used, slow down as well.

Post written by Neil Lakeland, Observer with the Kent Group of Advanced Motorists. Originally posted on the Mid-Kent Group of Advanced Motorists blog on 2nd October 2014

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