Rear fog lights are bad for safety
Discussion
Due to the fact that we should "Drive at a speed that will allow you to stop well within the distance you can see to be clear", surely rear fog lights artificially lengthen that distance.
In heavy fog you're driving and get used to seeing rear fog lights and drive at a speed which will allow you to stop well within the distance that is between you and the car with fog lights on in front of you. But then something is on the road without rear fogs [another vehicle or a junction or a deer or a kid or a tree] and you haven't time to react because you are not driving within the distance you can see to be clear.
Would it not be safer if we got rid of rear fogs?
In heavy fog you're driving and get used to seeing rear fog lights and drive at a speed which will allow you to stop well within the distance that is between you and the car with fog lights on in front of you. But then something is on the road without rear fogs [another vehicle or a junction or a deer or a kid or a tree] and you haven't time to react because you are not driving within the distance you can see to be clear.
Would it not be safer if we got rid of rear fogs?
You are leaning on an open door with me on this, Artie. Unless and until all vehicles (including motorcycles and bicycles) have them, and we can definitely say that they will always be used in fog, then they confer no advantage. I will not even bother to explore the area of road users, such as pedestrians, who are always going to be unlit.
Rear fog lights are a nuisance. Some drivers switch them on at the first sign of fog and then think they need do nothing else to be safe. It does not occur to them to slow down when the fog thickens so that they can still stop well within the distance they can see to be clear. Many will then go on to leave them on for a period of many days after the fog has passed, leading to the rest of us being blinded in rain.
Rear fog lights are a nuisance. Some drivers switch them on at the first sign of fog and then think they need do nothing else to be safe. It does not occur to them to slow down when the fog thickens so that they can still stop well within the distance they can see to be clear. Many will then go on to leave them on for a period of many days after the fog has passed, leading to the rest of us being blinded in rain.
Artie Fufkin said:
Due to the fact that we should "Drive at a speed that will allow you to stop well within the distance you can see to be clear", surely rear fog lights artificially lengthen that distance.
In heavy fog you're driving and get used to seeing rear fog lights and drive at a speed which will allow you to stop well within the distance that is between you and the car with fog lights on in front of you. But then something is on the road without rear fogs [another vehicle or a junction or a deer or a kid or a tree] and you haven't time to react because you are not driving within the distance you can see to be clear.
Would it not be safer if we got rid of rear fogs?
I agree with this and it broadly reflects the views I expressed on a thread in this forum recently (further down the page). It is also the view of several motor manufacturers, so I have been told by those in the industry. Have a look at the thread (sorry I don't know how to post the link but you should find it easily enough). In heavy fog you're driving and get used to seeing rear fog lights and drive at a speed which will allow you to stop well within the distance that is between you and the car with fog lights on in front of you. But then something is on the road without rear fogs [another vehicle or a junction or a deer or a kid or a tree] and you haven't time to react because you are not driving within the distance you can see to be clear.
Would it not be safer if we got rid of rear fogs?
Inappropriate use of fog lights, on the other hand, is a much more common problem and wouldn't happen if the damn things weren't there!
Steve
I would disagree 
as you say, the driver has an obligation to drive within their capacity to stop - so every car / no cars / some cars with rear fog lights makes no difference as there could be pedestrians / wildlife / etc. as mentioned...
but that is not their big advantage - that lies in the ability to add information into the picture you build and while you have to drive to the lowest level of knowledge (something not illuminated), it is only helpful to have a wider picture / more knowledge, so knowing awareness of other vehicles helps - it doesn't mean that you then drive at a speed based on those vehicles - that is simply bad driving, but the answer is the driver driving according to what might also be there, not making assumptions - and rear fog lights doesn't change that ability / inability...
I would also want to maximise the picture / information I have as a driver, so in this instance it helps a lot...
And there are some roads (e.g. motorways) which it really does maximise the picture... and others (local country roads) where it doesn't present a full picture, but still better than not showing them
the issue is driver attitude, not the lights
as you say, the driver has an obligation to drive within their capacity to stop - so every car / no cars / some cars with rear fog lights makes no difference as there could be pedestrians / wildlife / etc. as mentioned...
but that is not their big advantage - that lies in the ability to add information into the picture you build and while you have to drive to the lowest level of knowledge (something not illuminated), it is only helpful to have a wider picture / more knowledge, so knowing awareness of other vehicles helps - it doesn't mean that you then drive at a speed based on those vehicles - that is simply bad driving, but the answer is the driver driving according to what might also be there, not making assumptions - and rear fog lights doesn't change that ability / inability...
I would also want to maximise the picture / information I have as a driver, so in this instance it helps a lot...
And there are some roads (e.g. motorways) which it really does maximise the picture... and others (local country roads) where it doesn't present a full picture, but still better than not showing them
the issue is driver attitude, not the lights
I always put them on in bad visibility. On the motorway it's a big boon - if I'm toddling along at in heavy spray, keeping up with the traffic, and some idiot decides that they have x-ray vision and hoons along at 100mph, I want them to be able to see me from as far away as possible.
I can see your point regarding stopping distances, but consider the reverse - enough fools drive along in fog with no lights at all, and any change to the rules to limit their use would make that more likely.
I can see your point regarding stopping distances, but consider the reverse - enough fools drive along in fog with no lights at all, and any change to the rules to limit their use would make that more likely.
davepoth said:
I always put them on in bad visibility. On the motorway it's a big boon - if I'm toddling along at in heavy spray, keeping up with the traffic, and some idiot decides that they have x-ray vision and hoons along at 100mph, I want them to be able to see me from as far away as possible.
I can see your point regarding stopping distances, but consider the reverse - enough fools drive along in fog with no lights at all, and any change to the rules to limit their use would make that more likely.
You sound like someone who uses them inappropriately unless you mean that you use them in heavy spray when there is also enough fog to restrict visibility sufficiently to warrant using them - which is rare. In heavy spray fog lights do not usually add anything to the "picture" and either get misinterpreted as brake lights, mask the activation of brake lights on your or another's vehicle and create dazzling red glare further restricting visibility for following motorists. I can see your point regarding stopping distances, but consider the reverse - enough fools drive along in fog with no lights at all, and any change to the rules to limit their use would make that more likely.
Of course, one could argue that one shouldn't use rear lights in the dark at all on the same logic that I am applying to the use of fog lights in fog. However, the reality is that almost all drivers do use their rear lights in the dark and know how to use them properly. This, combined with the facts that most drivers don't know when to use fog lights appropriately and that modern rear lights penetrate well enough through most fog conditions to make driving to the conditions perfectly safe (i.e. not providing a false sense of security) lead me to the conclusion that fog lights are mostly an unnecessary nuisance.
If I was driving in conditions where I thought that I might actually hit or be surprised enough by another vehicle to have to take evasive action because they were not using rear fog lights then I would question the ability to proceed at all; certainly the speed would have to be very low. Where conditions make driving essentially impossible e.g. during a dust storm in certain parts of the world the correct procedure is to get off the road and turn all of your lights off, so that anyone stupid enough to drive in such conditions does not think that you are on a road and drive into you in a state of spacial disorientation.
The few times I have used fog lights in my driving career have been in very heavy fog (which rarely lasts long in most parts of the UK) where I was certain there was no following traffic, especially on smaller country roads where there is a good chance someone might round a corner too quickly not appreciating another vehicle may be driving at a much reduced, appropriate speed. In these cases as soon as following vehicle(s) have come into view and slowed I would then switch off the rear fog lights.
I also think rear fog lights are redundant these days. Normal tail lights are as good as fog lights used to be and the weather is rarely bad enough to warrant the use of front or rear fog lights in England. Because of this; people who don't drive often seem to think that they need to use them in light fog.
In over 10 years and probably 250,000 miles there have been two occasions (at night in very heavy fog) where I've concluded that front fog lights would improve my forward visibility and probably 5 instances where rear fog lights would have improved my rear visibility.
For this to be the case; visibility has to be less than 15 feet IMO.
Whenever I think about using them I look at the other traffic on the road. If I can see it; there is no need to use fog lights.
In over 10 years and probably 250,000 miles there have been two occasions (at night in very heavy fog) where I've concluded that front fog lights would improve my forward visibility and probably 5 instances where rear fog lights would have improved my rear visibility.
For this to be the case; visibility has to be less than 15 feet IMO.
Whenever I think about using them I look at the other traffic on the road. If I can see it; there is no need to use fog lights.
I'm the same. Probably about the same number of times I've ever actually felt they would have been of use.
I had anarguementdiscussion with my wife a few weeks ago that turning on the fog lights should automatically restrict you to say about 30mph, on the basis that if you need fog lights then that's already way too fast a speed to be going and if you can see far enough to drive faster you don't need them.
She disagreed but mostly on the basis of (not) being able to accelerate out of trouble and the idea that with speed limiters in place on all cars they'd then be activated for other reasons...
I had an
She disagreed but mostly on the basis of (not) being able to accelerate out of trouble and the idea that with speed limiters in place on all cars they'd then be activated for other reasons...
If visibility were to be as low as 15 feet, I'd say it's virtually impossible to go anywhere in the car.
As for the idea of front fog light usage being related to road speed, I'd do it the other way round from what was proposed above: I would suggest that front fog lights should be arranged so that they only work at speeds lower than about 20 mph, as I don't think they are much help to the driver at higher speeds, though they would help to make the car more visible to others.
As for the idea of front fog light usage being related to road speed, I'd do it the other way round from what was proposed above: I would suggest that front fog lights should be arranged so that they only work at speeds lower than about 20 mph, as I don't think they are much help to the driver at higher speeds, though they would help to make the car more visible to others.
davepoth said:
I always put them on in bad visibility. On the motorway it's a big boon - if I'm toddling along at in heavy spray, keeping up with the traffic, and some idiot decides that they have x-ray vision and hoons along at 100mph, I want them to be able to see me from as far away as possible.
I can see your point regarding stopping distances, but consider the reverse - enough fools drive along in fog with no lights at all, and any change to the rules to limit their use would make that more likely.
Having them on in fog or heavy spray when there are other cars directly behind you is going to be annoying to the traffic immediately around you and possibly mask your brake lights.I can see your point regarding stopping distances, but consider the reverse - enough fools drive along in fog with no lights at all, and any change to the rules to limit their use would make that more likely.
Surely the correct use is to use them in fog, not rain, when there is no visible traffic behind you. As soon as you see headlights behind at a normal distance then your rear fogs should be switched off, as the car behind will have seen you.
The other morning I was behind a car, and as we went into a misty patch, on came their rear fogs, even though I was immediately behind them. All it did was dazzle me and showed the other driver had not really thought about what they were doing.
I would be in favour of doing away with rear foglights altogether. Tail lights on cars are bigger and brighter than they were 20 years ago. If we must have foglights maybe we should only be allowed one on the rear below bumper level to minimise dazzling drivers behind, and to avoid masking the brake lights.
DocSteve said:
You sound like someone who uses them inappropriately unless you mean that you use them in heavy spray when there is also enough fog to restrict visibility sufficiently to warrant using them - which is rare. In heavy spray fog lights do not usually add anything to the "picture" and either get misinterpreted as brake lights, mask the activation of brake lights on your or another's vehicle and create dazzling red glare further restricting visibility for following motorists.
Highway Code rule 226:226
You MUST use headlights when visibility is seriously reduced, generally when you cannot see for more than 100 metres (328 feet). You may also use front or rear fog lights but you MUST switch them off when visibility improves (see Rule 236). Law RVLR regs 25 & 27
Stopping distances:
Stopping distance at 70mph is one car length short of 100m.
A handy rule of thumb is that if you are on the motorway and have moderated your speed due to poor visibility, fog lights are probably appropriate.
davepoth said:
DocSteve said:
You sound like someone who uses them inappropriately unless you mean that you use them in heavy spray when there is also enough fog to restrict visibility sufficiently to warrant using them - which is rare. In heavy spray fog lights do not usually add anything to the "picture" and either get misinterpreted as brake lights, mask the activation of brake lights on your or another's vehicle and create dazzling red glare further restricting visibility for following motorists.
Highway Code rule 226:226
You MUST use headlights when visibility is seriously reduced, generally when you cannot see for more than 100 metres (328 feet). You may also use front or rear fog lights but you MUST switch them off when visibility improves (see Rule 236). Law RVLR regs 25 & 27
Stopping distances:
Stopping distance at 70mph is one car length short of 100m.
A handy rule of thumb is that if you are on the motorway and have moderated your speed due to poor visibility, fog lights are probably appropriate.
Steve
DocSteve said:
The HWC link doesn't add anything in my opinion and the handy rule of thumb you quote would mean one should switch on fog lights at night as a matter of routine. Poor visibility due to spray and fog are different entities - penetration of light and clarity of vision do not go hand in hand, for a start. I agree with several of the posters above.
Steve
How would that mean switching on fog lights at night? Visibility isn't restricted just because it's dark. The rules of the road in the UK state that it's OK to turn on fog lights when visibility becomes restricted, and in my experience it's easier to see a car that has fog lights switched on in those conditions. Steve
titian said:
My simple rule for driving in fog is, can I see anything in my mirrors, no, then switch on my rear fogs. As soon as headlights apppear in my mirrors, switch them off. I'd much rather following traffic can see and react to my brake lights than be blinded by my fog lights.
this100% sadly they were invented by Eurocrats just as vehicle lights were getting better if they were still a dim,feeble and tiny as say morris minor rear lights then extra lights would have been a good idea my main objection is why have two?? all that does is masks brake lights and dazzles!!
I wonder how many rear shunts are caused by fog lights crying wolf?? ie people driving in poor visability and mistaking brake lights for for foglights?
Artie Fufkin said:
Due to the fact that we should "Drive at a speed that will allow you to stop well within the distance you can see to be clear", surely rear fog lights artificially lengthen that distance.
Based on the same logic I surely should not be driving at night either given that neither pedestrians nor trees have any lights at all (unless its Christmas I guess).In Germany there is a very clear law: If the visibility is more then 50 metres, you must switch them off. If visibility is below that, you must switch them on. If I can see your headlights through the fog that doesn´t mean you can see me and for my part I will keep using my rear fog lights whenever foggy conditions make them usable.
djcatshow said:
Based on the same logic I surely should not be driving at night either given that neither pedestrians nor trees have any lights at all (unless its Christmas I guess).
But headlights illuminate unlit things at night, so I don't see how your point is valid to what I was saying regarding rear fog lights?There are two issues with measuring visibility.
Can you see the outline of the vehicle behind? If so then there is absolutely no need for high intensity rear lights as you see position lights before the vehicle outline.
If you can see the vehicle lights but not the outline then high intensity lights may be appropriate, but it's a judgement call based around distance and fog density. If they're a 100m or so behind then definitely not necessary.
If you can't see anything behind, it a grey wall, and visibility in front of you is 100m or less then it's probably a good idea to put them on.
Those are my rules.
Agree with the general objections to folks who bang them on and then drive as if they've now got x-ray vision.
Can you see the outline of the vehicle behind? If so then there is absolutely no need for high intensity rear lights as you see position lights before the vehicle outline.
If you can see the vehicle lights but not the outline then high intensity lights may be appropriate, but it's a judgement call based around distance and fog density. If they're a 100m or so behind then definitely not necessary.
If you can't see anything behind, it a grey wall, and visibility in front of you is 100m or less then it's probably a good idea to put them on.
Those are my rules.
Agree with the general objections to folks who bang them on and then drive as if they've now got x-ray vision.
IMHO rear fog lights should be used in the same way as high beam headlights are used.
If you're on high beam and you see a car approaching you dip your beam so as not to dazzle them.
If you can see the head lights of the car behind you the chances are they can see your rear lights, so why continue dazzling them with your fog lights?
If you're on high beam and you see a car approaching you dip your beam so as not to dazzle them.
If you can see the head lights of the car behind you the chances are they can see your rear lights, so why continue dazzling them with your fog lights?
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