One or two rear fog lights - any research on which is bette?
Discussion
I've been involved in a discussion on another forum about the optimum number of rear fog lights.
I'm aware that EU legislation allows for either one or two rear fogs lights (and that our American cousins don't require any), and of the arguments on both sides, but my question is whether there has been any actual scientific research looking at whether - used correctly - cars are safer with one, or with two, rear fog lights.
Also, do the IAM/RoSPA/etc have any views on the matter?
I'm aware that EU legislation allows for either one or two rear fogs lights (and that our American cousins don't require any), and of the arguments on both sides, but my question is whether there has been any actual scientific research looking at whether - used correctly - cars are safer with one, or with two, rear fog lights.
Also, do the IAM/RoSPA/etc have any views on the matter?
I may be wrong but I wouldn't expect much if any research has been done into the subject.
They started off in the 70's if my memory serves me correctly , as a bolt on option, usually suspended from the rear bumper.
They were much better, in my opinion, when they were well away from the rear light clusters.
They started off in the 70's if my memory serves me correctly , as a bolt on option, usually suspended from the rear bumper.
They were much better, in my opinion, when they were well away from the rear light clusters.
Ramona said:
Thanks. What I'm trying to find out is what actual research or evidence supports (or refutes) this view?
None. It's an excuse cooked up to justify penny-pinching...Every new car for nearly 20 years has had three brake lights, and many for longer. Rear fog lights were compulsory here for less time than that before they were introduced.
TooMany2cvs said:
JonV8V said:
Colour blind people can get confused
What with?No more than they can get confused with other red lights, surely?
[quote]Don't some lorries/trailers only have 2 brake lights?
I have mild colour blindness (if you don't understand this you don't understand colour blindness) and find as much info in the intensity of the light as the absolute colour. It's hard to explain - it's easier to establish the light you're looking at in contrast to another light. Side and fog could look very much like side and brake.
JonV8V said:
Side and fog could look very much like side and brake.
Umm, yes, a 5w red and a 21w red light could quite easily look very much like a 5w red and a 21w red light. That's not particularly colour-blindness dependent.But a bright red light each side doesn't look very much like a bright red light each side PLUS a bright red light in the middle.
Anyway, if you've got a single bright red light visible, is it a single rear fog or something with one or even two brake lights out?
Would it be possible to move the discussion, interesting as it is, to its own topic?
My question was about what hard, scientific evidence or research (if any) exists to show whether one or two rear fog lights is safer.
If there is none, would it not behove a road safety body (IAM? RoSPA? ABD?) to commission that research, rather than allow vehicle manufacturers to decide for themselves?
My question was about what hard, scientific evidence or research (if any) exists to show whether one or two rear fog lights is safer.
If there is none, would it not behove a road safety body (IAM? RoSPA? ABD?) to commission that research, rather than allow vehicle manufacturers to decide for themselves?
Ramona said:
I've been involved in a discussion on another forum about the optimum number of rear fog lights.
I'm aware that EU legislation allows for either one or two rear fogs lights (and that our American cousins don't require any), and of the arguments on both sides, but my question is whether there has been any actual scientific research looking at whether - used correctly - cars are safer with one, or with two, rear fog lights.
Also, do the IAM/RoSPA/etc have any views on the matter?
Yes , Mercedes-Benz did some research into this before the lights were first implemented into the 1973 revision of the W114/5 'New Generation' series .I'm aware that EU legislation allows for either one or two rear fogs lights (and that our American cousins don't require any), and of the arguments on both sides, but my question is whether there has been any actual scientific research looking at whether - used correctly - cars are safer with one, or with two, rear fog lights.
Also, do the IAM/RoSPA/etc have any views on the matter?
It was determined that a single 'high intensity rearguard lamp' was better positioned away from the existing clusters since this would not be mistaken for brake lights , and would not distract from other lights such as signals .
Some prefer two lights , which arguably give an impression of distance , but since they don't have to be as far apart as other lights , this impression can be distorted .
TooMany2cvs said:
Umm, yes, a 5w red and a 21w red light could quite easily look very much like a 5w red and a 21w red light. That's not particularly colour-blindness dependent.
But a bright red light each side doesn't look very much like a bright red light each side PLUS a bright red light in the middle.
Anyway, if you've got a single bright red light visible, is it a single rear fog or something with one or even two brake lights out?
Mercedes-Benz use 10W tail lamps on many models .But a bright red light each side doesn't look very much like a bright red light each side PLUS a bright red light in the middle.
Anyway, if you've got a single bright red light visible, is it a single rear fog or something with one or even two brake lights out?
I heard that the view of some vehicle manufacturer's is that there is no need for rear fog lights at all, as modern lights are sufficient in almost all circumstances.
Certainly, I'm minded to agree with that view. It is extremely rare in my experience to be in a situation where I am unable to see a vehicle's rear lights but can see the fog light (in fact, I would say it has never happened). On the other hand, fog lights being used inappropriately is a common problem which undoubtedly creates distraction.
Certainly, I'm minded to agree with that view. It is extremely rare in my experience to be in a situation where I am unable to see a vehicle's rear lights but can see the fog light (in fact, I would say it has never happened). On the other hand, fog lights being used inappropriately is a common problem which undoubtedly creates distraction.
Pontoneer said:
I'd have to disagree : in properly foggy conditions , rear fog lamps are visible long before tail lamps can be seen ; there is a difference in intensity which penetrates further .
I agree with this. One one occasion I've been in fog so thick that I could barely see anything outside at all. Regular rear lights were invisible even with a care directly in front, and only the presence of the fog lights made cars visible. As you can imagine, we were crawling at perhaps 5 MPH and this was on the M4 at 2am.I'd much prefer to have see two fog lights in as part of the normal light clusters as it enables me to judge distances. I don't care if I can't tell whether I'm seeing fog lights or brake lights - at least I can see that a vehicle is there!
My own BMW E46 came with only a single bulb holder despite having a fog light lens and reflector in each light cluster. I bought the missing bulb holder as a spare part for about £5 and wired it up from the other side. Now I have two working rear fog lights...
Sushifiend said:
My own BMW E46 came with only a single bulb holder despite having a fog light lens and reflector in each light cluster. I bought the missing bulb holder as a spare part for about £5 and wired it up from the other side. Now I have two working rear fog lights...
Sigh! Despite repeated requests, it appears impossible for people to either stay on topic, or to start their own thread about the merits of one or two rear fog lights! What's so difficult to understand, people?!@Sushifiend - what hard, scientific, peer-reviewed, quantitative evidence led you to modify your car in this way? Or did you just do so on a whim because you thought that it might be better, despite the possibility that it might actually compromise your safety?
I recently commissioned the university of Royston Vasey to conduct some scientific research to quantify the most effective number of rear fog lights.
They came to the conclusion that the optimum number of rear fog lights is 26.
There are downsides to 26 rear fog lights - they tend to mask the brake lights a bit, but most following drivers tend to become instantly blind anyway, so they usually drive off at the first corner long before running up your rear end.
They came to the conclusion that the optimum number of rear fog lights is 26.
There are downsides to 26 rear fog lights - they tend to mask the brake lights a bit, but most following drivers tend to become instantly blind anyway, so they usually drive off at the first corner long before running up your rear end.
Ramona said:
Sigh! Despite repeated requests, it appears impossible for people to either stay on topic, or to start their own thread about the merits of one or two rear fog lights! What's so difficult to understand, people?!
@Sushifiend - what hard, scientific, peer-reviewed, quantitative evidence led you to modify your car in this way? Or did you just do so on a whim because you thought that it might be better, despite the possibility that it might actually compromise your safety?
None. Most of the things I do in daily life are not because of peer-reviewed, scientific evidence; instead I usually use my own experience and intuition. Just so with the foglight modification. @Sushifiend - what hard, scientific, peer-reviewed, quantitative evidence led you to modify your car in this way? Or did you just do so on a whim because you thought that it might be better, despite the possibility that it might actually compromise your safety?
I made the decision that since *I* find it easier to judge distances in fog with two rear foglights, I feel safer if drivers behind me have the same opportunity to judge my distance when they are behind me. In other markets, the same car is sold with both rear fog lights installed from the factory, and having both installed in the UK is perfectly legal. Since I had the power to make a choice, I availed myself of it. My previous car - also a BMW 3-series but of the previous generation (E36) - had both fog lights installed from the factory.
As for your exasperation that people are straying off-topic, I suggest that is down to you defining your topic too narrowly. If you only want answers that pertain directly to your question in a yes/no format with no further discussion allowed, then really you should have posted a survey with only two possible responses. You might have asked specifically about scientific evidence, but it's perfectly valid netiquette for people to discuss the subject in general. Starting a new thread to discuss the same issue but without the scientific evidence component seems not only redundant but just a little overzealous.
So if you felt that the best way to get to your destination was by driving at 120mph all the way, while simultaneously texting your friends and undertaking any cars that got in your way, that's what you would do, despite the evidence to the contrary?
You don't need to lecture me in netiquette - I've been using Usenet since 1986 - and my original posting was very deliberately framed to say that I was already aware of the arguments on both sides of the divide.
What does surprise me is that people dissect and debate Roadcraft and the "system" in microscopic detail (some even write whole books on the subject), giving the rationale behind every tiny item therein, yet something which could potentially have a major effect on road safety appears to have no evidential basis behind it. It's left to the car manufacturers, and well-meaning amateurs who have read something on an internet forum about how they can just stick another bulb in their car, to decide whether to use one light or two.
I would have expected that a forum such as this - where most of the discussions centre on why we should do certain things - to have been interested in finding out what is the optimal number of rear fog lights.
You don't need to lecture me in netiquette - I've been using Usenet since 1986 - and my original posting was very deliberately framed to say that I was already aware of the arguments on both sides of the divide.
What does surprise me is that people dissect and debate Roadcraft and the "system" in microscopic detail (some even write whole books on the subject), giving the rationale behind every tiny item therein, yet something which could potentially have a major effect on road safety appears to have no evidential basis behind it. It's left to the car manufacturers, and well-meaning amateurs who have read something on an internet forum about how they can just stick another bulb in their car, to decide whether to use one light or two.
I would have expected that a forum such as this - where most of the discussions centre on why we should do certain things - to have been interested in finding out what is the optimal number of rear fog lights.
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