The various meanings of flashing your high beams

[1995hoo]

If a vehicle is coming the other way and the driver flashes the high-beams, I check to see if I forgot to dim mine. (When I first got my current Acura, sometimes jerks flashed their brights at me because they didn't like the HID headlights that come standard on the car. That hasn't happened in several years, so I guess people are accustomed to improved headlights.)

If it's daytime and I see a driver coming the other way flashing his high-beams, I interpret it as warning of a speedtrap. (Some people flash the low-beams on and off instead.)

I've heard some people say you should flash your high-beams to tell someone he forgot to turn on his headlights, but I've always understood that flashing your lights on and off is the correct way to send that message.

I do not understand the current fad of shining your high-beams at someone when you don't like his driving.

But it's OK to blind other motorists with your Acura.

Nobody's "blinding" anybody. HIDs are standard equipment on many cars. People who don't like them need to get over it. I believe most have. I'm sure there were people who complained when the halogen lights started replacing the horrid old sealed-beam lamps too. Why should we all drive around with obsolete crappy old headlights just because some people don't like modern lighting?

[bugo]

No.  Those hideous blue headlights hurt my eyes and cause more damage than an incandescent bulb on bright.  Not to mention, the jacked up pickup truck or SUV with the headlights mounted 2-4 feet above where they are supposed to be causing light pollution and blinding oncoming drivers.  It could be a single screw that needs to be adjusted that would fix the problem.  The bottom line is that new car does not always equal car with correctly aimed or designed headlights, and many old cars, especially cars that have been in accidents need to have their headlights aimed.  One person with a bright light shouldn't be able to use it if it is blinding drivers.

[1995hoo]

Well, put it this way: If someone high-beams me because he doesn't like my low-beams, I'll high-beam him right back and show him what REAL high-beams look like.

Sort of reminiscent of Crocodile Dundee.

Haven't had that happen in several years, though. I think most people are used to HID headlights, especially people living in major metropolitan areas (simply because there are so many more cars than there are in rural areas).

[J N Winkler]

I have found HIDs objectionable in the past and suspect the main reason they don't bother me much anymore is that I now rarely drive at night.  I have wondered, however, if Euro-style full-cutoff beam patterns and automatic headlamp levelling mechanisms are becoming more prevalent, since HIDs seem less annoying on newer models.

I am personally not inclined to see any change in headlamp light source necessarily as a technical improvement, because headlight design is actually a complex optimization problem that has to take account of multiple factors:

*  Enough light to see pavement markings for tracking purposes

*  Not so much light that sign messages "burn out" against bright high-performance sheeting backgrounds

*  Light hued away from most drivers' chromatic ranges of higher sensitivity (this is the reason the French for many years required headlamps tinted "automotive yellow," though I believe EU directives now make this unenforceable; HIDs move in the opposite direction since they output blue-tinted light and in some models actually make it impossible to see white retroreflective sheeting as a true white)

*  Not so much light that it compromises the night-time accommodation of other drivers, thus increasing the chances that they will make tracking errors that result in a crash (in which you personally might be involved)

In the last 110 years or so, we have seen headlamp designs progress from acetylene to ordinary incandescent to sealed-beam incandescent to sealed-beam halogen to semi-sealed-beam halogen to HID.  It may be stretching it to say that acetylene with optimized beam pattern is equal to or better than HID with bad beam pattern, but for any electrically operated light source I believe it is true to say that beam pattern is far more important for usable nighttime illumination than the type of source used.

[agentsteel53]

the jacked up pickup truck or SUV with the headlights mounted 2-4 feet above where they are supposed to be causing light pollution and blinding oncoming drivers.

I'm astonished that this is legal. 

[vdeane]

Nobody's "blinding" anybody. HIDs are standard equipment on many cars. People who don't like them need to get over it. I believe most have. I'm sure there were people who complained when the halogen lights started replacing the horrid old sealed-beam lamps too. Why should we all drive around with obsolete crappy old headlights just because some people don't like modern lighting?

I get blinded EVERY SINGLE TIME a vehicle with HIDs is behind me or passing on the freeway.  It doesn't help that since I drive a smaller car rather than an SUV or truck that the headlights shine directly into my mirrors.

[US81]

Well, put it this way: If someone high-beams me because he doesn't like my low-beams, I'll high-beam him right back and show him what REAL high-beams look like.

Sort of reminiscent of Crocodile Dundee.

Haven't had that happen in several years, though. I think most people are used to HID headlights, especially people living in major metropolitan areas (simply because there are so many more cars than there are in rural areas).

Respectively: I've been in the situation (when HIDs were new) of drivers turning on and leaving them on for several seconds just in the way you describe - "I'll show you what high beams really are" - which left me so blinded I had to stop in the lane of traffic and wait to regain enough vision to be able to drive again. Terrifying.

The difference between rural and urban drivers probably has much more to do with dark adaptation than the idea that urban dwellers are more modern and up-to-date. It's not so much that I'm "used to it" but that I'm prepared for it now; we other drivers have had to develop coping behaviors to prevent being incapacitated by the oncoming fireball.

[vdeane]

Maybe that's why I have problems with them.  Almost all of my night driving is rural, and driving at night for me usually only happens when coming home from a roadmeet or trips to visit family.

[1995hoo]

Respectively: I've been in the situation (when HIDs were new) of drivers turning on and leaving them on for several seconds just in the way you describe - "I'll show you what high beams really are" - which left me so blinded I had to stop in the lane of traffic and wait to regain enough vision to be able to drive again. Terrifying.

....

I don't mean this to sound nasty and I apologize if it does. But frankly, I don't have a lot of sympathy for someone who flashes his high-beams because he doesn't like HIDs and then finds himself "blinded" when the HID user turns on his own high-beams. I feel that he brought it on himself. (With that said, I don't believe in the "turn them on and keep them on" thing, either; a quick flash back is plenty.)

[US81]

Respectively: I've been in the situation (when HIDs were new) of drivers turning on and leaving them on for several seconds just in the way you describe - "I'll show you what high beams really are" - which left me so blinded I had to stop in the lane of traffic and wait to regain enough vision to be able to drive again. Terrifying.

....

I don't mean this to sound nasty and I apologize if it does. But frankly, I don't have a lot of sympathy for someone who flashes his high-beams because he doesn't like HIDs and then finds himself "blinded" when the HID user turns on his own high-beams. I feel that he brought it on himself. (With that said, I don't believe in the "turn them on and keep them on" thing, either; a quick flash back is plenty.)

It's not that people "don't like" HIDs, it's that (especially when they were still new), people mistook the dim setting for the bright one. Not everyone, not even all road geeks, keep up with changes in headlamp technology, so not everyone was immediately attuned to the idea that there was a whole new magnitude to be encountered in cars. Some drivers - not necessarily you, just an occasional jerk - would not just flash, but leave them on for several seconds. Going from rural dark to that kind of bright can be a true hazard.  A quick flash is all that was needed to provide the information that, no, this is in fact the dim setting.

[kphoger]

I've taken to flash-dimming my lights rather than flashing my brights in many situations.  I do it when someone needs to turn their lights on (dimming them to show the difference).  I do it when I'm giving way at an intersection/crosswalk/whatever, assuming it's dark enough to have my lights on (sort of like a headlight version of nodding my head to the other driver).  I really only flash my brights anymore to warn of a danger, and then I do it multiple times to stress the point that there's something to watch out for.

HIDs

[Alps]

How do you communicate to someone behind you that their brights are on? I've tried pointing/waving, flashing brake lights or taillights... It's easy to do for oncoming traffic, but I can't just swing my car around 180 and flash them.

[1995hoo]

How do you communicate to someone behind you that their brights are on? I've tried pointing/waving, flashing brake lights or taillights... It's easy to do for oncoming traffic, but I can't just swing my car around 180 and flash them.

Once upon a time you held up your hand, turned it sideways, and made a gesture similar to the one you might make when you surreptitiously want to indicate to someone that someone else is talking too much–you know, kind of opening and closing your hand as though it were a mouth. It meant "check your lights." I used that gesture successfully during the 1990s, but I think its meaning has been lost. Makes me thankful for an auto-dimming rearview mirror.

[Truvelo]

Over here flashing your lights can have opposite meanings to elsewhere. Instead of letting other traffic know you're coming through it's often used to let vehicles out of side roads or to let oncoming vehicles proceed if there's an obstruction in the road narrowing it down to a single lane.

On freeways truckers will flash their lights to let a truck passing them know it's safe to pull back in.

Of course, flashing lights (usually several times in quick succession) is used to inform oncoming traffic of a speedtrap or if animals are in the road.

If by "over here" you mean the U.K., it's certainly not opposite from U.S. usage, at least in my experience. But more broadly, that's an important point; evidently in my example I ran across a driver who comes from a place where flashing lights is used prohibitively rather than permissively, and it's that unspecificity of meaning in this kind of signal that got me interested in the question.

I've never encountered a situation when driving in the US or Canada where I've had someone flash their lights to let me through. I therefore assumed the US is much like mainland Europe where flashing is used prohibitively.

[1995hoo]

Funny, I just flashed my high-beams (driving my wife's car, not HIDs) yesterday in heavy traffic near Harpers Ferry, West Virginia, to signal a guy on a side road to go–and he immediately understood the gesture and went. (Aside from being friendly, I wanted to piss off the guy behind me who was being a dick and not letting anyone merge or enter from side roads.)

[empirestate]

I've never encountered a situation when driving in the US or Canada where I've had someone flash their lights to let me through. I therefore assumed the US is much like mainland Europe where flashing is used prohibitively.

How interesting; did you instead see the signal used prohibitively in your time in the U.S., or just not at all? And were you driving in areas where there might be a high percentage of drivers who picked up their habits overseas? Could there, indeed, be pockets of the U.S. where even native drivers use their high beams prohibitively?

[corco]

How interesting; did you instead see the signal used prohibitively in your time in the U.S., or just not at all? And were you driving in areas where there might be a high percentage of drivers who picked up their habits overseas? Could there, indeed, be pockets of the U.S. where even native drivers use their high beams prohibitively?

I've never had somebody flash their lights at me to either let me through or prohibit me, but I suspect if somebody did I'd just be confused (keeping in mind that a good 95% percent of my driving has been in Rocky Mountains/Plains/Pacific Northwest/Southwest States (excluding California)  I'm not sure that light flashing is a common practice in even the whole of America.

[Pete from Boston]

How do you communicate to someone behind you that their brights are on? I've tried pointing/waving, flashing brake lights or taillights... It's easy to do for oncoming traffic, but I can't just swing my car around 180 and flash them.

You don't have one of those scrolling LED signs in your rear window like they use in the store window of dry-cleaners and the like?

If possible, I slow down so they'll pass and stop being my problem (sucks to pass it on, but if I can't see ahead of me because I'm seeing spots from high beams, I'm in danger and need to correct it).

Sometimes I'll then give them some few-second bursts to get them to figure it out.  I find that in general, this works less and less.  Motorist attention to oneself and others is not what it used to be.

[Truvelo]

If someone behind you has left their turn signal running the usual thing to do is alternate left-right-left-right your own turn signal in quick succession. That usually gets them to cancel it. Again, as per my last comment, this may only be a British thing and I'm not sure how you would go about it in North America.

[jeffandnicole]

If someone behind you has left their turn signal running the usual thing to do is alternate left-right-left-right your own turn signal in quick succession. That usually gets them to cancel it. Again, as per my last comment, this may only be a British thing and I'm not sure how you would go about it in North America.

It all depends on the mentality of the person behind you.  Some people will understand what you are trying to do and will turn off their turn signal.  Others will think that you have no clue where the hell you're trying to go.  "Really? Left turn, right turn?  There are no turns on the street. What an idiot!", says the guy with only their DRLs on at 10pm with the left turn signal on for 13 miles.

Speaking of - that's another reason to flash your lights - to try to get the person to understand that only their DRLs are on.  About a month ago I did see someone get pulled over for this - a woman in a minivan with only her DRLs on late in the evening.  She was doing about the speed limit on the highway, and was probably freaking out wonder why she got pulled over while others were passing her!

[kphoger]

If someone behind you has left their turn signal running the usual thing to do is alternate left-right-left-right your own turn signal in quick succession. That usually gets them to cancel it. Again, as per my last comment, this may only be a British thing and I'm not sure how you would go about it in North America.

I've done that quite a bit, even throwing in some brake lights into the mix.  Only about one driver in four (or fewer) gets the message.  I've given up.

[agentsteel53]

Speaking of - that's another reason to flash your lights - to try to get the person to understand that only their DRLs are on.

that, or their headlight switch is on that intermediate setting that every damn car seems to come with between "lights off" and "lights on".  not once in my life have I intentionally used it, but there have been times (including once getting pulled over) where I thought I had turned the dial two full clicks, but it was only one.  I fail to see what the purpose of it is other than inviting mistakes.

[triplemultiplex]

"Flashing the high beams" means to me, "Wooooo!! Spring break!!!"

[Alps]

If someone behind you has left their turn signal running the usual thing to do is alternate left-right-left-right your own turn signal in quick succession. That usually gets them to cancel it. Again, as per my last comment, this may only be a British thing and I'm not sure how you would go about it in North America.

I tried waving my arm out the window in the direction of the blinker. Nothing. The car was also going quite slowly in front of me in the left lane and notquiteleavingenoughroom on the right for passing.

[paleocon121171]

I've seen other drivers flash their high beams to inform drivers on the opposite side of the road that there is a police car logging speeds up ahead.

While I hear this reason many times for flashing your high beams during the day, there has only been ONE person who has been kind enough to warn me of such a speedtrap. When I was a kid driving with my parents, it was much more common for people to flicker their hi-beam lights to signal a police car. I don't see it much anymore though. However, if possible, I try my best to advise fellow motorists of law enforcement looking for speeders, especially if they're hidden.