If they are really helpful, why EU is still not passing laws to make them mandatory? They seem to favour lots of useless stuffs like DRL etc.
I personally don't find them much useful. In thick fog, lighting fog lamps never made situations any better for me.
Rear fog lamps are again dazzling - people seem to use them as rain lamps.
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Headlights (main or dipped) are useless in fick thog,
Fog lights enable the driver to ascertain their position on the road, at the very least,
I've driven through fog so thick that I was literally driving blind and am glad my car is fitted with sed lights.
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Front fog lamps provide a wide, bar-shaped beam of light with a sharp cutoff at the top, and are generally aimed and mounted low. They may be either white or selective yellow. They are intended for use at low speed to increase the illumination directed towards the road surface and verges in conditions of poor visibility due to rain, fog, dust or snow. As such, they are often most effectively used in place of dipped-beam headlamps, reducing the glareback from fog or falling snow, although the legality varies by jurisdiction of using front fog lamps without low beam headlamps.
Use of the front fog lamps when visibility is not seriously reduced is often prohibited (for example in the United Kingdom), as they can cause increased glare to other drivers, particularly in wet pavement conditions, as well as harming the driver's own vision due to excessive foreground illumination.
The respective purposes of front fog lamps and driving lamps are often confused, due in part to the misconception that fog lamps are necessarily selective yellow, while any auxiliary lamp that makes white light is a driving lamp. Automakers and aftermarket parts and accessories suppliers frequently refer interchangeably to "fog lamps" and "driving lamps" (or "fog/driving lamps"). In most countries, weather conditions rarely necessitate the use of fog lamps, and there is no legal requirement for them, so their primary purpose is frequently cosmetic. They are often available as optional extras or only on higher trim levels of many cars. Studies have shown that in North America more people inappropriately use their fog lamps in dry weather than use them properly in poor weather.
Wiki.
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In HK front fog lamps are used for ornamental effect - habitually, in fact many drivers use them with (or instead of) their dipped headlamps whatever the weather conditions. I'm sure the highway code is based on that from the UK but I've never seen the police enforce this, it's 'cool' after all.....
Rear fogs are used by some, often inappropriately, however many cars are Japanese imports and aren't fitted with them (doesn't Japan have fog then - or the US for that matter) ?
Anyhow, one thing I've noticed is that some cars which are fitted with 'active headlamps' (usually HID) no longer have front foglamps fitted or deploying the front fogs causes the beam pattern on the HIDs to alter. The examples I'd cite would be a 330d BMW I drove (in thick fog) and the latest facelifted C-Class and E-Class Mercedes which appear only to have LED URLs. In the BMW when you switched on the front foglamps the headlamp beam shortened, I found this irritating so didn't use the front fog lights (despite the thick fog)....
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>>Rear fog lamps are again dazzling - people seem to use them as rain lamps.
Quite right too. They are for use when visibility is less than 328 feet as it often can be on account of spray on a motorway.
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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). www.direct.gov.uk/en/TravelAndTransport/Highwaycode/DG_069859
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Dog seems to have said it all above. It seems to me that front foglamps, because of the nature of their beams, should only be used on their own, without headlamps, in the conditions for which they are intended. But it seems not many see it my way.
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Some relevant discussion within this thread from last year:
www.car4play.com/forum/post/index.htm?f=2&t=4306
Last edited by: Bromptonaut on Tue 8 Nov 11 at 14:41
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Bromptonaut, if we were to be banned from discussing anything that had ever been discussed before, this place would be very quiet... ;)
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Funny thing is i haven't driven in a real pea souper or dangerous freezing fog since the days of sealed beams and the first halogen headlamp bulbs, the only fog lights in those days were round ones you'd buy from an accessory shop (Halfords a bike shop then?) and mount under your chrome bumper.
I'd have givven me eye teeth for a light that could have illuminated further than the 10 to 15ft max visibility, 20 mph was too fast at times and often walking pace only.
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Isn't the point of foglamps that, being mounted low, they can illuminate the bottom few clear inches that usually lie under the fog? The beam can stretch ahead when headlights are up against the fog and thus give some help.
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In the old days, there were two types of lamp used in pairs, one as a "kerb-finder" and the other more of a general illumination...
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>> a "kerb-finder" and the other more of a general illumination...
>>
Presumably the former helps in areas of ill repute..;)
where's BBD when you need him.
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Used to point one at the kerb - the kerb finder, and one at the centre line - the cats eye spotter.
My old man had a pair of Lucas quartz Iodine ones, one was always loose and pointed in the air. He called that one the Owl Spotter.
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I suppose I'll get hammered again for this but those old-fashioned Notek 'Blue Spot' foglamps, used as above, were pretty good in my memory. But IIRC in those days you could use them legally without headlamps at the same time.
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i seem to recall they worked better than the silly little fog lights they fit now.
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>> i seem to recall they worked better than the silly little fog lights they fit
>> now.
>>
That's so true, those silly little things in the bumper of the C2 must be there for show or a bad joke by the designer, get more light from a powerful torch out the window...
and yes i've done that before too, and a wiper blade and arm by hand from the drivers window when the wipers packed up, oh and a squeezy bottle of water for windscreen washing.
Last edited by: gordonbennet on Tue 8 Nov 11 at 15:25
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>>Isn't the point of foglamps that, being mounted low, they can illuminate the bottom few clear inches that usually lie under the fog? The beam can stretch ahead when headlights are up against the fog and thus give some help<<
Precisely - headlights would just bounce back at you reducing your vision even more.
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It is impossible to have the front fog lights switched on in a VW without the headlights. You pull the light switch out one position for front fog lights and two position for both front and rear. You cannot pull the switch out with the switch in the auto, off or sidelights position.
I'm not convinced how useful the DRL are on my car. I can switch them off in a menu. When the main lights are on the DRLs are of course off.
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>> I'm not convinced how useful the DRL are on my car. I can switch them
>> off in a menu. When the main lights are on the DRLs are of course
>> off.
>>
Agreed; the DRLs in mine can be switched off, though I'm sure when the headlights lights are on the DRLs stay on too.
I don't think I've actually got any front foglights though. The car is fitted with what MB call Intelligent Lighting System (?) which adapts the shape and direction of the beam to the road / traffic conditions (there's a future MOT nightmare if ever I saw one!!), but I think the DRLs are where the fog lights would otherwise be. Also I can't picture a swich for them; there's only one fog light switch, which must be for the rear one since that's mandatory
Peter
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>>It is impossible to have the front fog lights switched on in a VW without the headlights<<
I would deem that to be a design fault.
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"Isn't the point of foglamps that, being mounted low, they can illuminate the bottom few clear inches that usually lie under the fog?"
Your point goes against the theories of fog formation - radiation fog is caused by cold ground cooling the air above to below its dew point temp so theoretically fog should be thicker closer to the ground and therefore thin as you rise higher because ground has less effect the higher you are in the fog. Advection fog is caused by warm moist air moving (slowly) over a cool surface again cooling it below dew point temp - should also be thicker nearer to the ground. Also, how do you see down to the " bottom few clear inches that usually lie under the fog?" from your position a few feet up?
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>> "Isn't the point of foglamps that, being mounted low, they can illuminate the bottom few
>> clear inches that usually lie under the fog?"
>>
>> Your point goes against the theories of fog formation
maybe, but there is always a small area near the tarmac that IS fog free due to the tarmac being warmer. , and you look down through the fog to the illuminated ground, with no light scatter or reflection back at you because there is no fog down there.
try it out, next time there is fog, lie down and look. Better still lie a torch on the ground and look at the light from your vantage point 6 feet higher.
Last edited by: Zero on Tue 8 Nov 11 at 19:29
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Good point Z - I guess the tarmac will absorb more of any heat available during the day and therefore be warmer at night when the cooling takes place and therefore have that lower layer of "clearness" that you ( and draiber) describe. Should have thought about it more!!
Mind you, I'm still not convinced that foglights are that effective - better than headlights but even using them you still can't see very far ahead.
Phil
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>>>>I'm still not convinced that foglights are that effective - better than headlights
>> but even using them you still can't see very far ahead.
>> Phil
I guess a bit better than headlights is the best you can expect.
I've used them in mist/fog as described in the earlier thread and occasionally in heavy snow. In both cases the lower more spread beam illuminates the road immediately ahead while avoiding the back dazzle that's present even on dipped heads. Doesn't change the safe speed for the circumstances, just improves the safety margin while keeping to it.
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I can 'see' what you're getting at Phil, but I can only speak from experience and say that using headlights in quite substantial fog is a no-no owing to light scatter and reflection (as Zed puts it)
The use of fog lights has enabled me to at least see the cats eyes to the RH side, and the kerb or whatever there was on the LH side but – I’m talking adverse conditions here, as in visibility down to just a few yards/mtrrs.
Regarding your “radiation fog is caused by cold ground cooling the air above to below its dew point temp” I must tell you this one ...
Chap on local radio today, a regular, and bit of a character BTW – reckons that when he had his old Morris 1000 van, he had a fish-tail type deflector on the exhaust pipe which directed the hot exhaust gasses down onto the road, so, he says ... if the fitment of these fish-tail deflectors became compulsory fitment on all cars, it would (wait for it, wait for it!)
Help to thaw the icy roads in winter :)
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Brilliant! - no need for winter tyres then
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Biggest problem with the usage of modern fog-lamps is that drivers seem to think that simply switching them on allows them to drive ar the same speed, and the same distance from the car in front, as they would if it were clear; some apparently think one can even drive faster from what I've seen.
With apologies to Bromptonaut, since I've posted this before; I believe it was Jeremy Clarkson who first suggested that fog light wiring should include a speed limiter which prevents the driver exceeding 40 miles per hour. The theory behind this is that if fog lights are indeed necessary, drivers should not be travelling any faster than this.
The principle idea behind this was not to curtail speed, but to deal with those annoying muppets who switch their fog lights on and then forget about them, to the intense annoyance of those drivers following, especially HGV drivers on a wet road since the glare reflects into your eyes.
As to whether or not they are actually necessary on modern cars, then the answer has to be no. Both front and rear lights have improved immeasurably since the mid-1970's when fog lamps were first introduced as standard fitment. Having said that, there seems to be a recent trend towards funkiness overtaking functionality, vis the recent thread regarding the difficulty in seeing rear indicators.
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>> With apologies to Bromptonaut, since I've posted this before;
My mention of the earlier thread was an atttempt to cross refernce subject matter rather than a just a minute style buzz for repetition.
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"using headlights in quite substantial fog is a no-no owing to light scatter and reflection (as Zed puts it)"
Quite agree Dog.
Trouble is, as Harleyman below says, people still don't drive within the "safety zone" ie, at a speed appropriate to how far ahead they can see/stop.
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>>Trouble is, as Harleyman below says, people still don't drive within the "safety zone" ie, at a speed appropriate to how far ahead they can see/stop<<
Ah, yes - the It will never happen to me mentality ... been there, done that and worn the t-shirt, fortunately I've come through unscathed, like most of us do,
Life is a game of chance really and we have to be 'out there' taking the chances, or we wouldn't progress beyond the cradle
Fortune favours the brave, mostly.
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>>Chap on local radio today, a regular, and bit of a character BTW – reckons that when he had his old Morris 1000 van, he had a fish-tail type deflector on the exhaust pipe which directed the hot exhaust gasses down onto the road, so, he says ... if the fitment of these fish-tail deflectors became compulsory fitment on all cars, it would (wait for it, wait for it!)
Help to thaw the icy roads in winter :)
Most modern cars seem to have their exhausts pointing down.
Can anyone explain a reason for this?
I would've thought the resultant stream of gasses would produce an amount of lift at the rear of the vehicle, not something you'd want.
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>>Most modern cars seem to have their exhausts pointing down.
Is this not due to emissions? My current VW has the exhaust pointing straight back. Twin exhausts on left of vehicle. But it is Euro V diesel.
Older cars (especially diesel) channeling emissions downwards?
Last edited by: rtj70 on Wed 9 Nov 11 at 00:48
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I also think it's to do with emissions, thought I think it preceeds Euro V because I had a diesel BMW in 2005 that had exhaust that pointed straight back and I think that only met Euro IV emisions. May well have had a DPF though, in which case perhaps that was the differentiator?
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>> I also think it's to do with emissions, thought I think it preceeds Euro V
>> because I had a diesel BMW in 2005 that had exhaust that pointed straight back
>> and I think that only met Euro IV emisions. May well have had a DPF
>> though, in which case perhaps that was the differentiator?
>>
I assume you are trying a wind up. If not I think the vehicle manufacturers will be delighted to discover that engine emissions can be varied by altering the the direction of the exhaust discharge.
I thought it was directed downwards to stop you getting your trousers or nylon stockings dirty while rummaging in the boot.
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>> I thought it was directed downwards to stop you getting your trousers or nylon stockings
>> dirty while rummaging in the boot.
Like I said it's emissions. The DPF cars are emitting less dirty exhaust particles and therefore don't need to point down. Exhaust emissions consist of more than just CO2 and NOx. There's the particles which are harmful and why we have DPFs - i.e. Diesel Particulate Filters.
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>> Like I said it's emissions.>>
>>
Stop digging, the direction of the exhaust output makes no difference to the emissions being produced by the engine. Shiny straight out the back exhausts are purely cosmetic, some factory fit ones are dummys (chrome tube welded to a downward bent pipe), you can still buy them in Halfords.
Last edited by: Old Navy on Wed 9 Nov 11 at 15:40
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I don't think we're suggesting that the direction makes a difference to the emissions; rather, a car that meets the more stringent emissions regs can have an exhaust that points straight out rather than down turned. We're further speculating that that's becuase of the lower particulate emissions, which might be DPF related.
Peter
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>> I don't think we're suggesting that the direction makes a difference to the emissions;
>>
OK I will give up on my pathetic fishing attempt. :-)
I still think the exhaust direction and bling is governed by aesthetics and cost more than anything else.
I don't think the locals would like exhaust up their kilts regardless of how clean it was. :-)
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I recall some exhausts having an upward turn in the '60s. Minis with Peco twin tailpipes exiting at the centre rear spring to mind.
Not unlike this: tinyurl.com/d96ljp3
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>> I recall some exhausts having an upward turn in the '60s. Minis with Peco twin
>> tailpipes exiting at the centre rear spring to mind.
>>
>> Not unlike this: tinyurl.com/d96ljp3
>>
Or this, DTM style?
tinyurl.com/cl7lf7d
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>>Chap on local radio today, a regular, and bit of a character BTW – reckons that when he had his old Morris 1000 van, he had a fish-tail type deflector on the exhaust pipe which directed the hot exhaust gasses down onto the road, so, he says ... if the fitment of these fish-tail deflectors became compulsory fitment on all cars, it would (wait for it, wait for it!)
Help to thaw the icy roads in winter :) <<
That's a perfect example of what I would call 'Morris Minor man thinking'.
There's loads of them out there and, in the face of all science and commonsense, they still believe the darn things are the best form of transport ever made.
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I've only had two cars with front foglights - a 406 estate that I did 150,000 miles in over two years and an Escort that I did 40,000 miles in over three years.
I reckon I used the front foglights in thick enough fog for them to actually help visibility, for a combined total of 10 minutes in both cars. I certainly don't miss them now.
The only reason I can think of why they *might* come in useful is because they are usually mounted substantially lower down than headlights, so the angle of incidence between the foglight's beam and the scattered light reflected back to the driver's eyes is greater - meaning the fog reflects less light back from the foglight beams than from the dipped headlight beams.
I can't figure out why some lorries, vans and cars have the front foglights mounted in virtually the same plane as the headlights (e.g. year 2000 Sprinter van, 2000 FIAT Punto, W202 C-Class, W124 E-Class) as they won't get the advantage of the lower position.
Last edited by: Dave_TDCi on Wed 9 Nov 11 at 20:55
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Do fog lights actually work? - Dog
