Headlight vocabulary?

November 13, 2006 8:11 PM

What are common courtesy signals for driving at night on highways?

It seems like every time I go on a long drive I see at least one person flash their brights, turn their lights on and off, etc. I'm not referring to the obvious circumstances, like warning the other driver they have their lights on, etc., but situations where one person is letting the other person know it's okay to pass, thanks for letting me pass, OMG DUDE DEER, or the like.

So is there some secret headlight vocabulary that I'm missing out on? An accepted system of one blink, two blink, lights on then off type dealio, or am I just imagining this phenomenon.

posted by ztdavis to travel & transportation (27 comments total)

The reasons I flash my high beams:

• It's your turn to go, at a 4-way stop, so go already
• I'm letting you out in front of me
• There is a cop up ahead, slow down
• There is a dangerous situation up ahead, slow down
• Turn off your damn high beams when you're coming at me
• Get out of my way, the left lane is for passing

There is no specific system of sequences of flashes, as far as I'm aware. And I'm sure everyone has their own systems which are vastly different from mine, ensuring a neverending rage-inducing situation.
posted by knave at 8:15 PM on November 13, 2006

for trucks, you are past me, you can pull in
posted by caddis at 8:19 PM on November 13, 2006

So is there some secret headlight vocabulary that I'm missing out on? An accepted system of one blink, two blink, lights on then off type dealio, or am I just imagining this phenomenon.

No, there is no vocabulary. Every flashing of the headlights means the same thing: Pay attention. Sometimes it means "Pay attention because there's a cop up ahead" and sometimes it means "Pay attention because it's your damn turn to go," but no matter how many times they flash their lights, it always means pay attention.
posted by BackwardsCity at 8:38 PM on November 13, 2006

I've also often seen the truck pulling in "thank" the truck behind them by turning on and off their hazards a couple of times.

I'll second everything knave said, too.
posted by one_bean at 8:41 PM on November 13, 2006

I rarely flash my lights except for safety reasons (the get-out-of-my-way flash is a pet peeve of mine). In the last year I've done a lot of high-speed night driving on rural interstates, and often I'll give a little flash-flash as I'm coming up fast to pass a a trailer truck just to make sure they know I'm there.
posted by hippugeek at 8:42 PM on November 13, 2006

Also, pay close attention to the four-way flashers (hazards). It's used to signal that highway or other fast-moving traffic has come to a standstill.

When signaling to trucks that they may come over, they often thank me by blinking their rear running lights.

But yeah, 99% of the time, brights flashing means "Hey!" and It's up to you and context to figure out why.
posted by Skorgu at 8:42 PM on November 13, 2006

In the US, there doesn't seem to be a consistent system, but if you drive in Mexico at night (which is dangerous) there actually is a simple system. A lot of the roads there are narrow and wind around hills, and many of the trucks are very slow.

When you would like to pass, blinking your lights indicates your intention to pull around. If it is unsafe to do so, they answer with a right turn signal. If the coast is clear, you'll be offered a left turn signal. Occasionally you'll see this "code" printed on mudflaps our painted on the back of the truck, but almost every trucker will respond in this way.
posted by ernie at 8:45 PM on November 13, 2006

Semi's will give you the lights off, lights on as a "thanks for letting me in"
posted by Pollomacho at 8:56 PM on November 13, 2006

I used to work for a promotions company that required that I drive across the US in a large 24 foot truck for months on end. From that experience, I know what many drivers (including myself) do to help fellow truckers and other drivers at night.

At night it's almost always better to signal to another driver by briefly turning your lights off and then back on again -- ONLY if it is safe to do so. This is done to avoid temporarily blinding a driver by flashing your high beams - either in their mirrors or directly into their windshield.

The following example assumes that you're following the basic keep right, pass left rules of the road.

If you're driving in the right hand lane and a truck or car that was behind you has entered the left lane in order to pass you:

• Once the passing vehicle is clear of your car and it is safe for them to re-enter the righthand lane in front of you, you should briefly turn your headlights off and back on to let them know it is safe to re-enter the left lane.


• If this courtesy is extended to you, it's good form to signal a thanks by briefly turning on your hazard lights.


• You'll probably find that when you extend this courtesy to truckers at night, they'll flash their hazards so that they only blink twice so it looks like: THANK -- YOU

Driving a 30 ton truck and doing the speed limit in the right hand lane at night can be extremely dangerous when there are cars zipping by at upwards of 90 mph. Even seasoned truck drivers find it hard to judge their distance from a car behind them at night. All they see are your headlights. Your signal lets the driver know it's safe to pass and lets them get back into the right hand lane as soon as possible without temporarily blinding them with your brights.

In every situation that the original poster lists above, briefly turning your lights off and on again is almost always the safest way to signal.
posted by plasticbugs at 9:02 PM on November 13, 2006

I flash my high beams for a few reasons: The main reason is to let you know you have your high beams on...TURN THEM OFF! Here in NJ I find myself doing this way more than I should have to. WTF people?

I also will flash my lights at a stop sign/intersection to signal the other drive to go first.

hippugeek said he was not a fan of the "get-out-of-my-way flash", but I have to admit that I use this when necessary. Here in NJ the left lane is technically pass only and if you are camped out doing 65mph I'm going to give you a quick flash to get you out of my way.

Like a few others said, another reason I would flash my high beams is to possibly alert traffic of a cop/danger ahead. I don't usually do this unless it's something pretty major because I don't think most people get the idea other than to check if their high beams are on and then proclaim me a dickhead once they find that their high beams are in fact not on.

Another signal I use is to turn my headlights on/off a few times to let somebody know their lights are not on at all. This seems to be more effective than flashing high beams.

Also, if you are ever driving behind me at night and you see me tap my brake lights a few times, check your high beams!! There is no good strategy for getting somebody behind you to turn their high beams off so I want people to start using this! Spread it around!
posted by jahmoon at 9:03 PM on November 13, 2006

Oops...

Once the passing vehicle is clear of your car and it is safe for them to re-enter the righthand lane in front of you, you should briefly turn your headlights off and back on to let them know it is safe to re-enter the RIGHT lane.
posted by plasticbugs at 9:04 PM on November 13, 2006

Also In some states like Georgia and Texas, you can actually get a ticket for flashing your headlights. They call it "impersonating an emergency vehicle".
posted by ernie at 9:11 PM on November 13, 2006

I also have noticed that something about the newer makes of headlight makes it -look- as though they are flashing hi-lo, when in fact they're just going over a slight bump or dip in the road. Rather like many SUVs always look as though they have their brights on; they don't, it's just the angle of the headlights makes them seem blindingly bright if you're in a smaller vehicle. I used to think people were flashing me constantly, until I really paid attention and figured this out.
posted by Rubber Soul at 9:46 PM on November 13, 2006

(the get-out-of-my-way flash is a pet peeve of mine)

What alternate means would you suggest to tell someone that they should move over because they're slower traffic that's not keeping right?
posted by ROU_Xenophobe at 9:54 PM on November 13, 2006

jahmoon writes "Also, if you are ever driving behind me at night and you see me tap my brake lights a few times, check your high beams!! There is no good strategy for getting somebody behind you to turn their high beams off so I want people to start using this! Spread it around!"

I find a couple flashes from 220Ws of backup lights to be wildly effective.
posted by Mitheral at 10:20 PM on November 13, 2006

I should clarify, I suppose: it bugs the hell out of me when drivers come up close behind me and flash their brights when there's no where else for me to go. If I'm in the left lane while a car is trying to pass me, it's because I'm already going as fast as I'm comfortable--usually significantly above the speed limit--and the right lane is too crowded for me to move over just then. There certainly are clueless drivers who will just park themselves in the left lane, and for them I support the judicious use of flashing as long as it's not accompanied by tailgating and other boorish behavior.

Thanks for the tip about impersonating an emergency vehicle, ernie--you may have just saved me a ticket in Georgia.

Love the tips for back-up lights and brake-tapping, Mitheral and jahmoon (friendly sidenote, though: this driver is a She). A friend's Volvo 850T (the car I've been driving fast through Georgia) has dual rear fog lights. Apparently these are illegal in some states because the pair of them looks too much like brake lights, but a previous owner installed them anyway. If anyone's tailgating, my friend flips the switch on the dash, the driver behind him thinks he's slammed on the brakes and follows suit while my friend mashes the gas pedal. Obnoxious, sure, and not safe in heavy traffic, but god it's satisfying to see that yawning chasm open up between you and the bewildered aggressive driver behind you.
posted by hippugeek at 10:34 PM on November 13, 2006

What alternate means would you suggest to tell someone that they should move over because they're slower traffic that's not keeping right?

The anxious driver could flash their brake lights by hitting their brake pedal, slowing down, not tailgating and being patient until the car in front moves over. Now, if it's just a slow-poke in the fast lane, flash away.
posted by Pollomacho at 10:58 PM on November 13, 2006

"(friendly sidenote, though: this driver is a She)"

How did I know that was going to get me into trouble. :P I didn't think about that until until after I posted. My apologies.
posted by jahmoon at 11:15 PM on November 13, 2006

No worries at all, jahmoon.

Does anyone else still turn on their lights during the day to warn oncoming drivers about cops ahead? I remember people doing this regularly when I was learning to drive (just 7 or 8 years ago), but the recent prevalence of daytime running lights seems to have rendered that courtesy ineffective.
posted by hippugeek at 11:32 PM on November 13, 2006

Flashing your lights to warn oncoming drivers about speed traps can get you in trouble if one of the oncoming drivers is also a cop. They may not actually ticket you, but they don't like you doing it, and will let you know it.

Many of the techniques mentioned here are degraded by the advent of daytime running lights. I can't turn my lights fully off to warn someone theirs aren't on; mine just get slightly dimmer, and my parking lights go off. I don't think that's really noticeable for someone who's probably averting their eyes from my lights anyway.
posted by Kirth Gerson at 4:09 AM on November 14, 2006

For urban driving, I frequently have to flash highbeams with the intent of saying "Hey, your lights are off." It almost never works.
posted by peeedro at 6:39 AM on November 14, 2006

Plasticbugs, the last several vehicles I've driven have lights that cannot be turned off at night without cutting the engine, so flashing the lights by turning them off doesn't work--I'd imagine that a lot of newer vehicles have that problem.

Hippugeek, I've had people flash me within the last year about police, but only where daytime running lights aren't required. I don't think I'd notice another driver flashing me in the daytime here (Fairbanks, Alaska), where most of the cars have lights on all the time.
posted by Cricket at 7:55 AM on November 14, 2006

can I piggyback on this question with another related question? On occasion, while driving on the highway, I've passed a semi and had him flash lights at me NOT to signal me to come back into the right lane (I was already there, and had by no stretch of the imagination cut him off), but after I was then in front of him. And again. And, sometimes, again. So, two to three full sets of flashing lights after passing - my brake lights were fine, my tail lights were on, etc, so he wasn't alerting me to a problem - what gives??

I also had one of these guys tailgate & cat & mouse with me for a while, which scared the bejeezus out of me. He wasn't the only one to do the multiple-flash thing, though, and the other drivers were courteous otherwise.
posted by AthenaPolias at 10:53 AM on November 14, 2006

AP, did you pass either of those trucks going uphill, then have them start the objectionable behavior after you'd reached the crest? Because they can't maintain speed going uphill with a load, and they like to be able to make up for it on the flat or downhill. If you passed them when they were slow, then prevented them from going as fast as they wanted, they might get frustrated.
posted by Kirth Gerson at 11:34 AM on November 14, 2006

When I want to get the attention of someone behind me, usually tailgaters...I pull my emergency brake up just enough for the lights to go on (test this in your driveway while the rear of your car is facing a wall so you can see how much it takes for the light to go on.) In my car and my parents car you don't have to pull it far, only about an inch, which isn't enough to engage the brake, but turns on the lights.

If it's a tailgater you can just leave it like that till they back off, or make it flash really fast..they'll have second thoughts no matter what car it is about you being a cop or not.
posted by Sonic_Molson at 11:49 AM on November 14, 2006

On occasion, while driving on the highway, I've passed a semi and had him flash lights at me NOT to signal me to come back into the right lane (I was already there, and had by no stretch of the imagination cut him off), but after I was then in front of him. And again. And, sometimes, again. So, two to three full sets of flashing lights after passing - my brake lights were fine, my tail lights were on, etc, so he wasn't alerting me to a problem - what gives??

Sounds like you passed him, moved back over, and just sat there at the same rate of speed. In other words, passed for no good reason. If so, that's a flashworthy offense.
posted by Tubes at 3:45 PM on November 14, 2006

I didn't - he sped up! hm.

Thanks, Tubes.
posted by AthenaPolias at 2:18 PM on November 15, 2006