Fog Lights? Are you talking about the add ons to the front of the car to throw more light lower on the road? Or are you talking about rear fog lamps as found on European cars? My opinion is that the front lamps are a hazard. Forget about adding more lights to the front of a car. Rear fog lamps, on the other hand are effective in preventing rear end crashes, in my experience. Why do I feel front "fog lamps" are a hazard? They distract other drivers, even to the point of momentarily blinding them. They give the drivers a false sense of visibility. They really don't enhance forward visibility in foggy conditions. Instead, they reflect more light to spoil the driver's night vision. Where do you drive? Califonia's central valley? Ohio? West Virginia? Maryland? Wisconsin? Are you trying to get enough light to drive at regular visibility speeds, even in fog? What happens when you come up on the mere mortal that has slowed down for foggy conditions? Fog crashes may be as related to sun angle as to visibility. Reference the White Marsh, Maryland crash. Road treatment may be more effective for driving in fog than adding lights to the car. Check out Skyline Drive in Oakland, California.

Hello Dick, I was talking about Fog lights in the front, but good point about having them in back, never heard of that. I will be driving in a Southern California mountain community. Good point about the mere mortal. I worry more about the "engulfed in fear" mortal doing 1 MPH or stopped dead in the middle of the road. Any pointers for driving in fog such as follow the white line in the slow lane where someone may be parked or the yellow line on the left. Any pointers at all are appreciated. Thanks for the help.

Jerry, Southern California? Sounds like you will be driving through clouds on the hillside. More like the fogs of West Virginia, Pennsylvania and Maryland. Hillside clouds usually burn off in the sun. If you are on the side of the hill, you get orographic lifting, which squeezes the water out of the air. Especially on the side toward water (Pacific Ocean or Lake). Check your local weather reports. Scheduling driving times to avoid fog is the best tactic. Valley fog is a different story. Usually a nighttime and early morning event. Valley fog can begin as early as sunset and last as long as noon. Low spots in the road seem to have heavier fogs. Onset of fog can be very sudden. October to March is usually the peak of fog season in California, but onshore movement of air masses from the ocean and sudden mountain showers can produce fog any time. If you are driving above 4,000 feet elevation, CALTRANS has usually marked the roadside with snow markers. Poles with several reflectors to guide the snow plows. In fog it looks like a three dimensional video game. The reflections give the appearance of a highway in the sky. People tend to speed up in the fog. They lose the peripheral clues of speed. Fog also seems to quiet things down. Look at your speedometer more often. You will suprise yourself when you find you are travelling faster than you thought. Don't brake too quickly, lest the car behind you doesn't see your brake lights. Learn to cover your brakes. That is, learn to apply just enough brake pedal movement to actuate the brake lights but not to slow the car. When a car is approaching from the rear, you will most likely see his headlights before he sees your tail lights. Don't use flashers. They induce vertigo and suggest to other drivers that you are stopped. When you fisrt notice headlights in the rear view mirror, cover your brakes to give the following car an indication you are there. Expect similar action from lead cars, but don't be surprised when tail lights appear out of nowhere. If you do have to stop off the road, turn off the lights and get out of the car. In some conditions you might leave the inside lights on. When following a truck with a lot of reflectors, leave enough room to not be blinded by the reflections. Make sure the INSIDE of your windows are clean. In foggy weather, the inside of the windows can fog very quickly, especially if they are the least bit dirty. Trurning on defrost also actuates the air conditioning and can lead to condensation inside the car. Be aware of the sun angle. Driving into a sunrise or sunset in the presence of fog can be a blinding experience. There was a chain reaction crash in White Marsh Maryland when a weather front passed. If the road curves into and out of driving into or away from a low lying sun, anticipate your eyes reaction to the varying amount of light. The eye reaction to light is a trick used by magicians to temporarily blind people so they don't notice the elephant being moved. Look away from the light. If you drive the same route, look for low lying areas. If there are water releases in the streams near the road, the water will possibly be cold enough to induce a flow of cold air and the formation of fog. When approaching traffic signals with precursor flashers, slow down. The signals and the fashers will make the fog "bloom". All you will see is light reflected from the fog. No high beams. In parking lots and at walking speed, parking lights may be more effective than headlights, but don't try this in California. I think driving with parking lights only is illegal. California's valleys have a more or less permanent inversion layer. Somewhere around 3,000 feet. Expect different visibility as you change altitude through inversion layers. Especially the inside of your windshield effect.

Good.

Jerry, I don't know of a specific study, but logically it maybe a matter of safety rather than increased vision on your part. Fog lights may not help you see the roadway out in front of you, but if a vehicle coming towards you can see your fog lights at a much further distance this will reduce the chance of a crash. Add the fact that you have REDUCED your speed because of the reduction in visibility the roadway has been made safer. Driving safely in foggy conditions is a drive modification issue and not and equipment issue. There can be a vehicle and roadway with the latest technology installed, but if the driver does not slow down to take advantage of these improvements all is lost.

There are obviously many misconceptions out there regarding a good set of fog lights I don't see them being much use in early detection by other drivers however the Red rears seem like a great idea in case someone is coming up too fast in fog etc. After 33 years of driving my opinion is this . Yes it is extremely rude to not be dimming them for oncoming traffic , however a good set with a flat beam patter when properly aimed should cause minimal glare to others as the beam should not be aimed at their eye level or lane. The color yellow seems to be deemed uneccessary however I've found it less fatiguing on the eyes against large (WHITE of course) snow flakes which can cause quite a glare, the yellow does minimize this glare. The main advantage I can see to have a set (regardless of color) is to have them mounted as low as practical therefore providing good illumination of the road surface but minimal glare or reflection back to your eyes due to the difference between the lighting and viewing angles. Again the biggest advantage is in snow as opposed to foggy conditions. I have driven a greyhound and switching them on and off to test the difference proved them invaluable.

Hi Everyone... I drive here in the Central Valley of California in Tulare
County where fog is most prevalent from November through February. (Today we
had a 108 car pile up on California 99, November 3, 2007, 2 people were
killed.) The best thing I can tell you if you are driving in the fog is to
SLOW THE HECK DOWN! Highway speed limits are posted for IDEAL CONDITIONS and
fog is about as far as you can get from ideal. Another trick is use going back
and forth to work each day in the fog is to turn on my GPS unit and have it
display the map of the area in which I am driving. You can easily become
disoriented in the fog and lose track of how far you've travelled along your
route, even if you know the road very well. With the GPS (zoom out the view)
you can have more than enough advance warning of roads that intersect your
route so you can be more cautious of traffic that might be crossing the
roadway. Many people drive with their driver's side window down to hear
traffic noises of oncoming traffic, but that can lead to other problems such as
your own car becoming full of fog. Best advice: SLOW THE HECK DOWN!

We manufacture a linear, solid plastic, embedded LED in-pavement lighting
system, called LEDline®, which we believe could help provide guidance to
drivers in fog and if properly applied keep driver speed down. However, to date
no one will do the research to prove our concept.

All the research I have seen indicates drivers tend speed in low visibility
conditions anyway, for a variety of reasons.

One of their main reasons for speeding is to keep up with and in close
proximity to the vehicle ahead of them, so that they do not lose the road
guidance that that vehicle provides. As in so many other situations, it is far
easier to follow a lead vehicle, to let the lead vehicle pick out and determine
the way forward and just follow it, than having to be the lead vehicle. (This
is in large part due to the fact that painted markings are not good in low
visibility conditions. Indeed at night, in heavy rains, snow whiteouts, dust
storms and fog, painted markings often completely disappear.) This leads
following drivers not to want to be the lead vehicle and to drive far closer to
the vehicle ahead than they normally would, so the stopping distances are much
smaller and drivers have to be much quicker to stop in time, or accidents
occur.

Having much less time to react also means that there is constant acceleration
and deceleration happening with vehicles speeding us so as not to lose site of
the vehicle ahead, then slowing down as they get too close. There is,
therefore, much less time to react, when a stoppage occurs, and which almost
guarantees that mistakes will happen. And, the constant speeding up and slowing
down creates a broken uneven traffic flow, with no rhythm in the traffic, so
there is an accordion effect and with the closer following traffic, with much
less stopping distances, again there is a tendency for accidents to happen.

The other main reason drivers site; when asked why they were speeding in the
low visibility conditions, was a fear of being rear ended. This feeds directly
into the previous argument as drivers tend to drive much closer together and in
bunches rather than spreading apart. Therefore the lead vehicle has the double
anxiety of having to pick his way along the road and is worried about being
rear ended, by the vehicle behind which are tailgating and following far too
close.

Whilst there are many other factors such as lack of visible signs of speeding,
here is a completely explainable feedback mechanism, as to why drivers speed in
fog; They speed because to its easier to follow rather than lead; ------- and
so as not to lose touch in fog with the vehicle ahead, drivers follow the
vehicle ahead far more closely than they normally would in good visibility
conditions; --------- which leads the driver ahead worrying about being
tailgated and rear ended, so they speed up to get away from the tailgating
vehicle behind; ----------- which leads the vehicle behind speeding up to keep
in touch of the vehicle ahead; ----------- which feeds back into the lead
drivers anxiety; leading to speeding, the constant adjusting of vehicle speeds
and distances, the uneven way vehicles proceed in fog and when the breaking and
acceleration reaches a certain pitch, (accordion effect) with the increased
probability of an accident, as someone miscalculates.

Providing no markings at all would of course, tend to slow everyone down, and
one would have more run-off the road accidents and this would be unacceptable.
By installing painted markings, in low visibility, the directional guidance is
slightly improved, reducing the run-off the road accidents, however, in bad fog
and other low visibility conditions, this guidance is not great and the
markings are hard to see. Indeed, in snow whiteouts and even heavy rains, at
night, painted markings often disappear completely.

We believe we have the answer to providing the necessary guidance in fog, and
yet also to prevent drivers from using the better guidance to further speed,
unfortunately we can not get funded to demonstrate our system.

If anyone or State has a low visibility area that they are concerned about and
is interested, please call 905 849-6134.

Fog Lights? The kind on the car? The kind on the road?

The kind on the car come in front and in back. I do not know why there are not
more cars equiped with the rear fog lamp. This is a red light with wattage
similar to a brake light rther than a parking lamp or turn signal. The driver
has a switch to turn it on and off. Most often seen in northern Europe where
black ice is common. Does that rear fog light work to prevent rear end crashes
in the fog? In my opinion, yes. Look in your owners manual if you have a Volvo
or BMW or ask your dealer. VW may have them, but I don't know if rear fog lamps
are legal in the United States.

Is it annoying to following drivers if the driver forgets to turn off the rear
fog lamp? As Governor Palin says: youbetcha.

Could the rear fog light have better design features? Youbetcha. The police
cars that I have seen in the central valley of California which lead platoons
of cars in fog are very effective. They could be more effective if they had
rear fog lights arranged in a pattern that not only alerted the following
driver, but had a pattern which gave an indication of the distance. Perhpaps a
distinctive CHMSL for police cars used as goats to herd the sheep in the fog.

From a distance, the rear red lamp causses the fog to bloom. As you get closer,
the bloom becomes a blur of red. Closer still and the blur becomes the car. If
you can see the car, you are too close. If there were two lamps, following
drivers would get an earlier indication of when they are closing and a better
indicatio of their following distance. I have never seen front fog lamps
illuminated on the goat car.

Front fog lamps on a car? Not very useful for the diver of the car with the
lamps. A huge distraction for oncomong drivers.

Fog lamps on the road? The best I have seen are the in road small lamps similar
to active Bott's buttons. The spacing gives an indication of speed. People
sometimes speed up in the fog because they lose peripheral cues and it is
quieter.

Hello all;
I wrote the text below in response to another thread, but it is appropriate to
do so here, and I've added a couple of bits.

SEEMS to me, once again, that the US needs a compulsory *rear fog lamp*
requirement for its new-market; car, van, SUV and truck/trailer fleet.

That this did not happen very many years ago, considering the lamp is also
useful for road safety - when used in wildfire smoke, dust-storms, torrential
rain (particularly in daylight rain storms) etc, is "serious negligence".

A change then to FMVSS108 to effectively adopt SAEJ1319 - the US recommended
practice! (SAE J1319 was created well over a decade ago).

A rear fog lamp offers up to 20 times the luminous intensity over a vehicles
standard-regular taillight performance. This equates to many seconds of
advanced warning!

The state driver manuals, would of course THEN need to highlight the correct
use of the rear fog lamp. ONLY one US state has this text, and has had a
number of years, and that New York State. Highway patrol to then enforce.

Readers will note increasing numbers of cars with rear fog lights, merely
'optionally' fitted. NHTSA need to change it to mandatory!

Companies like Hella USA have aftermarket rear fog lamps, compliant with
SAE-J1319.

You will of course need say a 3-pole switch that has an orange or yellow LED et
al. (Legally required; shows when the rear fog lamp is 'on').

Find a rear fog lamp with a dimensionally suitable size for your application.
You need only a single unit, you then mount this at the rear (duh),- LEFT of
the vehicles center-line (The US being an LHD country), a minimum 100mm (10cm)
away from any brake-lamp function. (To prevent masking of stop lamps).

IF two are used, for say heavy vehicles - the rear fog lamps must be
spaced_equally_apart, and a minimum 100mm (10cm) away from any stop lamp.

Mounting height; International rules vis; for cars, vans, SUV's - not higher
than 1000mm (1.0 meter) above ground level. 1.5m for trucks!

The lamp is earthed, a wire is then run from the lamp to the switch on the dash
for its power, the switch is also earthed (for the yellow/orange tell-tale
function), the remaining switch pole is connected to the cars low-beam
headlights OR the front fog lamp positive feed.

A rear fog lamp is cheap life and property insurance.

ONLY operate your rear fog lamp in "hazardous weather conditions causing
seriously reduced visibility", not simply because it is 'misty'.

A rule of thumb to help guide; in GB the lamp may only operate IF visibility is
reduced to less than 100 meters. (50 meters applies in Germany, and that is
very, very bad visibility).

Don't own a car without a rear fog lamp if your in a poor visibility prone
area, insist on one.

(Think also of carrying a safety vest or two, and a high-performance
hazard-warning triangle, US DOT type are 'okay', but the World/Global standard
type referenced "UNECE 27R" - in land transport regulation is even better).

Weblink One, 3M UK safety vests:-

solutions.3m.co.uk/wps/portal/3M/en_GB/Scotch-Lite/Home/HiVis_Lbl/HiVis_Importan
ce/

Weblink Two; French Government requirement for triangle and safety vests in
cars (EU Continent mandates triangle and vest):-
www.securiteroutiere.gouv.fr/article.php3?id_article=184

Regards.

dear sir, you're full of it. fog lamps penetrate fog due to the frequency of
the light emitted from them, penetrating past the fog. i've driven the highways
of b.c. for fourty years, and have seen some of the worst fog conditions know
to man. without fog lites i would have been forced to a dead stop. if they are
blinding oncoming traffic, they are misproperly alinged. ever tried driving
through white-out conditions without them? guys like you are the reason not to
believe everything you read on the internet. go ahead, put this on your
website. get your facts strait

Colin, Thanks for the response about fog lights. Someone with your driving
experience can probably adjust to low visibility conditions based on what you
learned from driving in many different condtitions. Not many drivers have that
experience, but like to think they have.

Can you share some of your earliest experiences of driving in fog, or heavy
rain or snow? The trips that you remember because they are over and done with.
The trips where you got out of the cab and kissed the ground?

By frequency of the light do you mean color? There are orange and blue tints on
some fog lamps and I've even heard of some polarized fog lamps. There may be
some halogen lamps with a hotter color. I don't know of any Xenon or gas
discharge dedicated fog lamps. Blue is scattered and reds don't reflect that
well.

How do you estimate distance in fog? In heavy fog, there is little peripheral
vision. In lighter fogs, its like inside a football. Look foward into the murk
and sideways into less murky. But still murky. Are there multiple forward
facing fog lights? Where do the lights converge? Does the convergence point
provide an estimate of distance? HOw many lane marker stripes can you see?

I saw a fog/smoke condition this morning on CA 20 near Hallwood at about ten
AM. Someone was burning agriculure debris near the Yuba River. There was an
inversion and a wind from the WSW below the inversion. Coming out of the
foothills dumped drivers into a short stretch of almost zero visibility from
combined smoke and fog. Confounding the fog/smoke was a change in direction
which added to a change in shadows. Very disorienting. Vertigo inducing. I've
seen layered fog on streches of that road where it was like driving in soup two
feet deep. You could see straight ahead above the fog, but could not see the
road. In low areas where the road dipped into the fog, you couldn't see
anything but what appeared to be the inside of a milk bottle.

CA 20 is similar to CA 65 and CA 99 in the aspects of Tule fog. What is
different is the amount of traffic and the mix of drivers. 65 and 99 have more
people that have never driven the route, let alone in fog.

There were some roads in South Africa fitted with the center line LEDs. Does
anyone have a link to the before and after crash statistics and return on
investment?