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Comment by sdfjkl | Hacker News Reader

Different cultures have different unwritten behaviours on roads.

In the mountains of Italy, drivers give a short honk before entering a turn on a serpentine road, which usually can't be seen around. If there is no responding honk, they will take the full width of the road (making the very tight turn easier and faster). Tourist drivers have to pick up on this :)

In much of Europe oncoming cars flash their lights to warn others about dangers and (especially) speed traps or police checks, so they can slow down in time.

Here in Lithuania, flashing your warning lights (the four orange ones on the corners of the car) means thanks, for example if you let someone merge from one of the very short onramps. I've never seen this in Germany, where onramps are however much longer.

And amongst truck drivers it's pretty wide-spread to blink right to tell a following car you think it's safe for them to overtake you and blink left when you think it no longer is. At least on long roads where there are no obvious right turns. I flash them a grateful hand sign when passing their mirror.

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Flashing the high-beams to warn of police is a thing in the US also, although you can get ticketed for it.

(Apparently this has been successfully challenged in court as free speech though lol https://www.myimprov.com/flashing-headlights-in-florida-prot... )

I remember reading through some of the judicial rulings on this. IIRC, the logic is that not only is it speech, but the government case for regulating this kind of speech is unusually poor: the function of flashing the lights is to suggest that you obey the traffic laws. That can't reasonably be in the government's interest to prevent.

Now that is an interesting point I never considered. That the message being conveyed is simply "Obey the law".

Not that the contents of the message should be germane (in my opinion) when considering whether a specific act of speech should be considered legal or not.

IANAL, but my understanding is that there are different levels of "scrutiny" that can be applied to a statute when analyzing its First Amendment compatibility, and which one is appropriate depends on several factors. Typically a judicial opinion walks through the logic of which one it applies before applying it. And the level of scrutiny determines how strongly the law is constrained.

Under the strictest scrutiny--applied when the law is restricting the expression of a viewpoint or opinion--it doesn't matter why the law is there; free speech wins. Under lower scrutiny, as seems applicable here, the government must show it has a "rational basis". That's what allows them to, say, require you to communicate your intention to turn via a turn signal. I believe that rational basis test is what's failing here.

This comes from Footnote Number 4 [0], which was literally a footnote in a case where a Justice articulated what the Court was already doing in analyzing its cases. The Court generally applies one of three levels of scrutiny [1]:

* Strict scrutiny - The Government must prove there is a compelling state interest behind the challenged policy, and the law or regulation is narrowly tailored to achieve its result.

* Intermediate scrutiny - The law must serve an important government objective, and be substantially related to achieving the objective.

* Rational basis review - A challenger must prove the government has no legitimate interest in the law or policy; or there is no reasonable, rational link between that interest and the challenged law.

While I don't believe the Supreme Court has taken up a case of light signaling, it is likely that the Court would apply strict scrutiny due to the clear First Amendment considerations. If so, thus the government would need to prove that it's narrowly tailored solution to a compelling state interest. It would need to answer questions such as: is it okay to say flash your headlights for road hazard? Would the state prohibit the defendant from telling others at a gas station about the police officer? Etc. I'd suspect that it would be a hard case to win for the Government.

[0] https://en.wikipedia.org/wiki/United_States_v._Carolene_Prod....

[1] https://www.findlaw.com/legalblogs/law-and-life/challenging-...

This is why rural Arizonan drivers were my favorite during a cross-country roadtrip. Everyone drove fast, but competently, and gave you a heads up for speed traps. By the time I crossed into CO I was flashing my lights to warn of police, too.

I've seen flashing lights to warn of speed traps used all over the south east and mid west.

Oddly though, no one in Southern California holds Arizona drivers in high regard. Quite the opposite. Best I can tell they're the western equivalent of Florida drivers.

A few years ago in Sydney Australia there was a couple of cops catching jaywalkers at a traffic light. My friend warned passengers at the other side about them, and then the cops came up to her and told her to move along because she was "obstructing justice".

Most people these days drive with their LED high beams on all the time.

I see the opposite problem more often (Bay Area): cars with always-on daytime running lights that don’t turn on their headlights (and the corresponding taillights) at night. I flash my lights at them but this rarely seems to help.

Cars have too many features.

And I don't mean this in a, "I'm a luddite and wish cars were simple" type of way. I seriously think the number of controls on a vehicle (and burden of the owners manual) is so great that it is causing safety issues.

My car has more controls for the lights alone than my first vehicle had for everything. Literally.

"Automatic" features like headlights were supposed to make us safer, but I think that is backfiring as it is causing cognitive overload and making people complacent.

> My car has more controls for the lights alone than my first vehicle had for everything. Literally.

As someone driving a 2021 Subaru who grew up in a 99 Integra and an 01 Civic. I don't see this at all? The controls are extremely familiar for the lighting, except my new car has a no-friction option: I turn on the "Auto" setting and it automatically puts on DRLs or full lights for me given the lighting conditions. It even turns on my lights for me when I pull into my parking garage at midday.

How exactly could this be made less complex?

I'm not sure what the solution is, or whether it is even a design problem at all, rather than a societal/political/licensing problem.

My older vehicles had 3 controls for exterior lighting: parking lights, headlights, high beam. They were simple on-offs with feedback that indicated their current state. If people couldn't see your car, you couldn't see your gauges.

My 2021 Honda has SEVEN pages in the owners manual dedicated just to the headlight operation -- not counting the several other sections it calls out for related information. Some sections are called out as US specific and some called out as Canadian model specific.

Let's take just the high-beams for instance:

Flashing the high beams is a different physical control than turning them on. Activating the auto-high beam functionality is somehow not a separate control, but is done flashing your high beams, and there is a not-very-clear symbol in the instrument panel that indicates the current state. This means that when you flash your high beams, you are also changing the current state of the auto headlights. If you flash it an even number of times you will keep the same state, if you flash them an odd number of times, you change the state. Furthermore if you hold the stick in for 40 seconds, you disable the auto headlight feature entirely. If you hold it in for 30 seconds, you turn it back on. Yes, there are two independent levels of "on" and "off" respectively just for the auto-high beams.

It works perfectly fine when you know what it's doing, but it isn't something that a person would automatically know if they were someone who started driving when you turned on headlights by pulling a knob on the dash.

Besides that one specific gripe, there's 160+ pages dedicated to just to controls and the instrument panel alone.

Anyone who reads a modern 600+ page owners manual will learn something. The problem is that people don't, and sometimes the thing they didn't learn is important.

I'm late to the party so no one will read this comment, but it's important for posterity. I own an F150 for moving things literally too heavy to move in even a well spec'd SUV. As a result, I cared a lot about things like load tie down points and weight ratings. In many ways, I learned an awful lot about that from the owner's manual, though in many other ways, I wish that they had better information about load placement in the bed and weight ratings of the bed liner in small areas, etc. You really can learn an awful lot that people should know about the limits of their vehicle from reading the manual.

On the other hand, we have legally required boilerplate sections like "how to decode tire ratings" that take up 20 pages, so there's definitely useless bloat.

What you describe here is clearly insanity, although I am slightly unconvinced owner's manual page count is very relevant.

I read nothing and intuitively understood my car's controls, this is what I also agree should be the clear state, and it seems to me in some sense it should be legislated to prevent what you describe. It is an interesting point though, should each vehicle manufacturer be obligated to put a light stick with some exact set of controls for the headlights in?

I don't think it is insanity. It's part of the complexity inherent to managing state with auto high beams. My Toyota worked differently but had other complexities. I just looked up a 2021 Legacy manual and it sounds like Subaru High Beam Assist works about the same way as my Toyota did.

The annoying thing about that design is, if I want to turn my high beams on manually, and the car decides that a street light in the distance is a vehicle, it will ignore my request to turn on my high beams when I push the stick forward. I then also have to set my primary headlights to manual mode in order to override the car. This requires turning the knob at the end of the stalk which is not backlit and therefore not legible while driving at night. This is one area where I like the Honda design better: I can always turn my high beams with one operation.

I think the page count is relevant because it is indicative of complexity and is likely inversely related to the number of people who read it.

While I am sure you probably do understand the controls on your vehicle -- I think it is important to note that the people driving around with lights in an improper state at night are also under the impression that they understand their vehicle's controls. They're just mistaken.

I personally wish licensing and enforcement was more stringent. But this is not politically possible in the US.

> The annoying thing about that design is, if I want to turn my high beams on manually, and the car decides that a street light in the distance is a vehicle, it will ignore my request to turn on my high beams when I push the stick forward. I then also have to set my primary headlights to manual mode in order to override the car. This requires turning the knob at the end of the stalk which is not backlit and therefore not legible while driving at night. This is one area where I like the Honda design better: I can always turn my high beams with one operation.

It's an Outback for what it's worth, but... High beams work directly by pushing the stick forwards. I haven't experienced it denying such a request, only correctly toggling off when traffic is both oncoming and within a reasonable distance, but if it did behave incorrectly in this way, I would simply pull the stick back and push it forwards to re-activate high beams. I don't think there is any complexity in managing state with this implementation, it seems inherently obvious to me it would be this way. I am very surprised with everything else you've written here because it seems quite extraneous.

> if it did behave incorrectly in this way, I would simply pull the stick back and push it forwards to re-activate high beams

In the Toyota that I had, if it thought there was an oncoming car, asking it to do the same thing again wouldn't result in a different outcome. Maybe Subaru's system is tuned better, or maybe my driving conditions are an edge case.

Either way, this was just an anecdotal tangent to support my above point that vehicle controls are more complex than they used to be. What was once one single boolean value is now a logic tree containing four boolean values ([auto headlight system engaged][vehicle detected ahead][vehicle speed within operational parameters][highbeams commanded by driver]).

> In the Toyota that I had, if it thought there was an oncoming car, asking it to do the same thing again wouldn't result in a different outcome

Why wouldn't the result of the action the second time be based on exclusively the stick's position and the current state the vehicle is in? Then it is a pure function of time. If they truly mixed up previous states in there, and somehow it's aware that in the history of positions it was at this position and at that time it rejected your request so it will also reject it now, that's braindead and you should phone Toyota and scream at them

My car's headlight's current state is a pure function of time T and position P. That's my mental model and I haven't observed deviations. I will look at these manuals later perhaps to understand if they really argue there are more stateful factors than this

The Subaru auto headlights work great indeed. Other Subaru smart functionality is crap though. For example, the touchscreen and gauges auto-dimming: literally every time it auto-dims or auto-undims, I have to tweak the dimming level. It would be an objectively better car without the auto-dimming.

> For example, the touchscreen and gauges auto-dimming: literally every time it auto-dims or auto-undims, I have to tweak the dimming level

I have never noticed this, fingers crossed you didn't Baader-Meinhof me. The feature to aim the lights where you steer and auto-dim high beams when traffic is approaching and re-activate them works quite nicely for me as well, so I would consider the headlights to be a great strength of this vehicle. It is crazy to get into my partner's mid-2010s sedan and laugh at how bad the lights are at nighttime compared to the perfectly aimed and calibrated Subaru lights

>It is crazy to get into my partner's mid-2010s sedan and laugh at how bad the lights are at nighttime compared to the perfectly aimed and calibrated Subaru lights

On the other hand, that mid 2010s sedan's headlight system will age gracefully - there are no aiming servos to fail or autodim relay output to stop working or such thing. It's just lights with a switch to turn them on or off.

Increased complexity also implies increased maintenance and often more troublesome failure modes when something does fail.

I would find it hard to believe that the failure mode of these headlights wouldn't be "points straight and doesn't auto-dim ever", which reduces it to the previous implementation's graceful aging modes, but you are right a new possibility is introduced.

I would absolutely believe the failure mode will be that one headlight will stop moving when it's commanded to, which best case means straight headlight, worst case means aimed where it shouldn't be 99% of the time

And whatever those failure modes are, they better be good, because in 20 years those vehicles will be on the road in some state without regular inspections, driven by someone without the money to pay for OEM electrical repairs.

Yup, I discovered that I have an automatic headlight dimming feature. It works well most of the time, often surprisingly well.

BUT, and this is a BIG BUT, it sometimes fails, and at the worst times - like when it is drizzly & foggy at night, in a tight bit of road and a lot of wet pavement glare from the oncoming car — so the workload is already high with bad visibility & grip, and now I have to ALSO flick the lever and move my eyes to the dashboard display to check whether or not I got the lights to the correct state (it may unpredictably finally work and my action goes back to high beams a half second later).

I keep being lulled into giving it a few more chances, but I'm pretty sure it'll get turned off for good. I already reliably switch the hi/lo beams at a subconscious level with near-zero mental workload, so I'm better off just letting that instinct work by feel, rather than randomly having to engage another higher-level attention task at particularly high-workload moments.

This is a Ford and I read that they had this same feature about a decade ago and had to remove it because it just wasn't good enough. It seems that they're a lot closer, but not enough.

Something like the uncanny valley of tech features - almost good enough makes it really bad?

Apple Car's on the way, hang tight.

One feature I really like about my car that I'd never seen before (2020 Explorer) is that the headlights will always return to automatic mode every time you start the car. It doesn't matter what they were set to when you turned it off, and there's nothing you can do to disable that behavior. When you turn it on, the headlights will be on automatic mode no matter what. It's a small but helpful feature.

This is a huge problem here in Michigan, too. Many cars come with automatic headlights, but many do not, particularly of a certain age, and the LED DRLs seem to be bright enough that people do not realize that they don't have their full lights on. I find this particularly infuriating in ugly snowstorms and the part of the year where the sun sets before 5:00pm... sigh

My theory is that these cars have multiple drivers.

Driver A is used to vehicles with manual headlights and always turns their lights off when they get out.

Driver B is used to "everything is automatic" and touches nothing when they get in.

This is very possible -- I had this exact situation with my girlfriend until I managed to get her used to leaving it in automatic mode.

I've never understood why DRL are only in the front.

I don't understand how a car with detectors that dim mirrors can't also turn your high beams off when they detect another car in front of you.

Easily 5/8ths or more of every vehicle I pass at night has their high beams on, and in areas without fog lines it gets old in a hurry - and dangerous.

This technology exists in Europe, it's not allowed in the US due to very specific wording about headlight laws here, but very recently regulations were changed to allow for it. Not sure if it was in the infrastructure bill that already passed, or the follow-up one they're currently trying to pass. Most BMW (and probably Mercedes, Audi etc) with adaptive LED lights built after ~2017 have the hardware for this for use in international markets, and could probably be retrofitted with a firmware update unlocking it for use in the US market.

This technology is not great on a windy[1] european road though. I rented a car recently and noticed that it was auto-dipping but the problem is it dips once it has detected the oncoming vehicle. That is fractionally too late as the driver has already been dazzled. Manually, I would dip the headlights just before the car came into view because I could see the headlights looming.

[1] a road with lots of turns, not one where the wind is blowing

“Winding road” is a nice way to disambiguate from gusty.

Auto high-beams is absolutely allowed in the US and common on new cars. I've had a couple cars with this feature.

My current car has auto high beams. Beam shaping is different technology, rather than a boolean operation, it allows the computer to turn off specific LEDs that are pointed at oncoming traffic, leaving the road ahead of you fully illuminated without blinding oncomming traffic

The GP specifically referred to a vehicle that would "turn your high beams off"

> it's not allowed in the US

My MDX does it, and they have had that capability since at least 2017.

I believe the tech that is not allowed in the US is something that literally dims sections of the lights that would shine line into the eyes of an oncoming driver. This is different than the auto dimming lights feature in US cars that just shuts off the high beams when an oncoming car is detected. Most of the tech is made by a company called Gentex. If you have an auto dimming rear view mirror in your car they most likely made it.

Press release about the feature I am referring to: https://ir.gentex.com/news-releases/news-release-details/new...

This article has pictures; perhaps easier for a quick overview: https://www.manufacturer.lighting/info/162/

> I don't understand how a car with detectors that dim mirrors can't also turn your high beams off when they detect another car in front of you.

Some can, though I have no idea on how common it is. My 2013 Dodge can do this. Unfortunately, it's also pretty terrible at it, resulting in a lot of on, off, on again, not quite flashing. e.g., a slight bend in the road, it doesn't seen anyone if front, turns high beams on, only for the road to bend back and all of a sudden your brights are shining in someone's face as the road bends back again. Sometimes, I've seen even changing lanes be enough for it to turn brights back on again. It also doesn't seem to give as much consideration when following someone as leaves them on way too close for me.

I live in an urban enough area with plenty of street lighting anyway, so I tend to use the auto high beam feature almost never (it can be toggled with a position of the turn signal lever). I do, however, use the auto-on lights in general, though. Nice to just not have to worry about turning lights on (or off).

I've also been pulled over before for flashing my brights at a police officer. It was entirely unintentional, though. I was a relatively new and young driver (17 or 18 yrs old at the time) and I was driving an older vehicle that still had a foot operated switch for the high beams that tended to stick.

Where do y'all live? That doesn't seem to be the case here in the Seattle area. I've noticed modern cars' headlight look like high beams sometimes, even on the low beam setting.

BMW does "automatic high beams" in Europe, they turn on when there are no cars ahead or opposite and off when it detects a car through the cameras. I've had it since 2006, so it probably existed a few years before that.

Our 2020 GMC Acadia and the equivalent Ford Explorer both automatically turn high beams on and off depending on nearby traffic. It's presumably based on a forward looking camera in front of the rear view mirror.

This feature is present in at least a couple of Toyota’s newer models that I’ve had the chance to drive (specifically a Prius Prime and RAV4 Prime).

Ford Edge (US market) has this too when in 'automatic' mode for the lights. It seems to work reasonably well though it sometimes lags a bit so other drivers probably find it somewhat annoying.

A switch to low and back will still be seen as a flash.

Edit: I do actually see this on the road all the time where I live. Just saying.

I hate this. It's incredibly dangerous and annoying.

in zanzibar they all have their brights on at night. everyone is blinded

I can confirm all of it for Germany as well (except the Italian serpentine road synchronization hack).

I flash lights for oncoming traffics because of danger or police checks.

I flash warning lights (or raise right hand) for thank you. Others do as well (especially buses, when you let them out of the bus stop, since in Germany they don't have the right of passage leaving a bus stop)

I learned that truck drivers (and buses) flash left, when it's not safe to overtake.

There are also some official rules regarding bus flashing at a bus stop (right, warning). But most of drivers ignore that.

I'm pretty sure I learned that if a bus has the blinker on when leaving the bus stop you are supposed to let them into traffic. A quick check seems to confirm it (§20/5 StVO).

Here in Montreal the buses leave the right signal on while stopped at a stop, then activate the left signal as soon as the doors close, even if they're in a bus lane that they don't intend to leave. To complicate matters further, they use the hazard lights while stopped at a timing point, so you can't tell just by looking at the left side if the bus is about to merge or if it's going to be stationary for the next 10 minutes.

Parts of this make sense, and I appreciate the consistency, but the execution leaves something to be desired.

Somewhat tangentially related, but the french government did an interesting ad on this (very entrenched in France too) habit of flashing lights after police checks: https://www.youtube.com/watch?v=VNsVZu-2IaA

It's somewhat common among truck drivers in Germany to flash the turn signals left-right-left-right to say "thank you" after overtaking (another truck).

I think it's usually right-left-right-left.

Maybe it's the other way when driving on the left? :)

Is that saying thanks? I thought they were just fumbling with the blinker control.

It's saying thanks as a response to the slower truck flashing its high beams to let the faster truck know it's now safe to move back over to the slower lane.

yes, that's saying thanks. It's equivalent to the hazard lights, but in some vehicles the hazard lights button isn't very accessible.

> I flash lights for oncoming traffics because of danger or /police checks/.

Why? Do you want dangerous drivers on the roads?

Attitudes like yours are what embolden governments to engage in revenue enforcement the proliferation of which leads to people tipping each other off about said revenue enforcement (e.g. flashing their lights to warn of speed traps). People wouldn't be warning each other about the cops if "people the cops shake down" and "people who were doing dangerous things just prior to being shook down" had more overlap.

I'm not sure I understand your point, unless you're arguing that national speed limits are deliberately low so that police can fine people driving at the "correct" speed? Or that police lie about your speed and fine you anyway?

The former is definitely true. There are towns out there in the United States that are on an interstate and play games with their speed limits. You'll see a speed limit of 60-70 up until you hit city limits then it suddenly drops to 30-40, with enforcement lined up at the city limits waiting to nab people.

They're making good money off of these fines.

But why wouldn't you want lower speed inside the city?

You normally would, but this is just predation on through traffic. It's not like you're going through the middle of main street, these may be off to the side of town with several exits but close enough for the city to dictate speed limits.

Flashing lights is meant to communicate to others they need to slow down or otherwise obey the traffic laws. How does that have a negative effect on safety?

> In the mountains of Italy, drivers give a short honk before entering a turn on a serpentine road, which usually can't be seen around. If there is no responding honk, they will take the full width of the road (making the very tight turn easier and faster).

I do this in the UK for the narrow lanes where there is only room enough for one car, because my Grandad used to do it, and because it makes a lot of sense... although the "take up the whole road" part is kind of unavoidable, which is the whole reason to beep ur horn. There are just a huge number of country lanes here that are so narrow only one small vehicle will fit, and when you get to a blind corner you have to go slow enough to be able to quickly stop... a couple taps of the horn help to warn other drivers that something is coming regardless of your actions, and just reduce the chances of a collision.

To be fair I rarely hear other drivers do this any more, so it might be more of an old fashioned thing.

A friend from Syria once told me that in their country flashing warning lights means "f* you", and when he saw it for the first time when going abroad, he was really angry when someone thanked him. Like "I've just let him merge and that is how he acts to me?!"

But I personally haven't heard of any other cases when this isn't considered a thank you gesture

In Israel the most common meaning is "Get off my lane, RIGHT NOW!", so I wouldn't be surprised if it's not just Syria but a big chunk of the Middle East that follows that rule.

It could also be used to call another driver's attention (e.g. if you have a broken taillight and did not notice), or to warn against a police trap (in the pre-Waze era) and maybe a few other things, but it never means "thank you".

Its contextual.

Car coming the other way flashes and it means hazard ahead.

If it's at night and your DRLs are the only thing on it means "turn on your lights moron"

At an intersection it usually means "go" to whichever party should be yielding to the flashing party.

Of course if you're in the left land and flash your brights at someone who's clogging up the left lane there's a good chance they won't understand it because if they could understand the context they wouldn't be clogging up the left lane in the first place.

I'm surprised at the thank you gesture. The intended use of warning lights is to... warn people, right? I've always understood them to mean "something weird has happened, and so I may do something unpredictable." I can't see how that could have morphed to "thank you."

Pretty sure the intended use is when stationary, to warn that you have broken down and are positioned badly.

At least, that used to be the only time it was legal to use them here (Sweden). They recently added a rule that it’s legal to use warning lights while being towed, too. Either way, it’s certainly a traffic offense to use them while driving.

In Israel, flashing the warning lights or hazard lights or whatever they're called when driving, means "hey car behind me, you're on high beams and blinding me, please stop". Since moving to the US I haven't found an effective way to signal people about this, they certainly don't understand this signal.

Flashing high beams quickly is either a warning about police ahead, or "turn on your damn lights" (there is also a hand gesture for this, spreading and closing your fingers towards them to illustrate a light beam). If someone is blinding you coming in front of you, you just turn on high beams and blind them back.

> Since moving to the US I haven't found an effective way to signal people about this, they certainly don't understand this signal.

Between lifted pickup trucks and shoddy, poorly-aligned aftermarket HID lights, it's probably that a high percentage of them AREN'T using brights, even if it feels like it.

Or even poorly aligned OEM lights. Most US states don't have vehicle inspections, and the ones that do usually aren't checking headlight alignment.

You have to have your headlights alignment tested every year in Israel. And being caught with badly aligned lights can lead to a ticket if a police car is on the receiving end.

A number of US states have inspections that cover proper operation of lights, but often in practice it isn't anything more than checking to make sure they aren't burnt out. Having improperly aimed headlights is also ticketable in the US but it isn't often enforced.

You can flash the rear fog lights for that. It's annoying enough for those behind you to at some point start looking at their own dashboard.

> If someone is blinding you coming in front of you, you just turn on high beams and blind them back.

I do this too and would die a peaceful death if we crashed into each other with the feeling of fairness restored to the world.

Repositioning your review mirror to reflect their headlights directly back into the driver's eyes is not a solution (tested empirically).

>there is also a hand gesture for this, spreading and closing your fingers towards them to illustrate a light beam

I try to use this in the US, though my success rate is rather low. And I wonder if the distraction just makes things less safe every time I do it.

How about when someone leaves their rear fog light on and you are behind them…

I've seen people flashing their hazards to say thank you in London, but never in Scotland. I suppose non-verbal, everyday communication like this can still remain very localised since the usual vectors for cultural transmission (social media, television, film, etc.) don't include such mundane things.

When I lived in one part of South London, I never saw this, or at least so rarely that I never figured out what it was supposed to mean. After moving to another, more suburban, part of South London, I see it all the time. shrug

Interesting, I live in Glasgow and commonly see people do this (and do it myself)

Trucks and some cars use their hazards as thanks here in Australia too (two blinks).

Trucks travel far though. I wouldn't be surprised that they would be a significant vector of road etiquette.

> Here in Lithuania, flashing your warning lights (the four orange ones on the corners of the car) means thanks, for example if you let someone merge from one of the very short onramps. I've never seen this in Germany, where onramps are however much longer.

In Sweden it's common to do this by using your blinkers. You blink once in each direction. So first left, then right. Or the other way around.

In the USA, I at some point picked up flashing headlights as "thanks", I don't know how common it is, I don't see it that often (anymore?), but USA drivers may be unlikely to give thanks on the road. :|

(Flashing headlights is also "i see you trying to merge in front of me and i'll give you space." Which I also occasionally do but don't see that often).

>Flashing headlights is also "i see you trying to merge in front of me and i'll give you space."

I do this for the same reason - or more generalized - 'I see you are about to do _x_, and I acknowledge - go ahead'.

The only way I've seen flashing high-beams used is on the highway to signal from behind "you're going too slow for my liking" or from a distance away "watch out I'm serpentining through traffic 15-20mph faster than the next fastest car"

I think GP is talking about flashing the headlights by turning them off and back on quickly, rather than flashing the high-beams. This is what I've usually seen in the US when drivers want to say "thank you" or "you can merge in front of me" on the highway.

Ah, ok. Yeah, that's an important distinction. I've actually not come across that as of yet.

I usually see the flashing headlights for "go ahead in front of me" around entrance ramps in busy traffic.

Not common, but maybe I see it 3 or 4 times a year.

> You blink once in each direction. So first left, then right. Or the other way around.

I've had this a few times from truckers driving through Germany, too, when I let them merge. Truckers in Germany are from all over Europe so it's hard to tell how European this gesture is

> In Sweden it's common to do this by using your blinkers.

I wouldn’t say it’s common here in Sweden, at all. I’ve driven all over Europe and the US, and nowhere is as uncommunicative as Sweden on the roads. People barely use their blinkers even when turning or changing lanes on the motorway, let alone ‘thanking’ each other - which in the 25 years I’ve lived here, I’ve seen maybe two or three times.

I’ve seen it all over the place, starting with my parents.

I guess using the warning lights as a “thanks” would be uncommon though, since it’s actually illegal. ;-)

I think this is originally a trucker thing, and I've seen it many times from truckers in the US. I've used it myself when someone is courteous and lets me in.

> In the mountains of Italy, drivers give a short honk before entering a turn on a serpentine road, which usually can't be seen around.

Swiss busses even have a special horn playing a piece (three tones) of Rossini's, Wilhelm Tell Opera Overture https://youtu.be/wMWEQdxMhdA

>> In the mountains of Italy, drivers give a short honk before entering a turn on a serpentine road

At night i was on an airport transfer bus heading down the Amalfi coast and the driver was flashing his headlights before barrelling into a hairpin turn giving no room for oncoming traffic. I stopped stamping on the imaginary brake pedal quite so hard when i realised this signal must mean I’m coming through which is the opposite from here in the UK where it means I’m giving way to you.

I learned both and it depends on the context. If you can see the other car and they can see you, flashing the lights means giving them right of way or showing them that they can go. If you are coming towards a blind corner it is just a way of bringing attention to you coming. I also do this when cars with high beams come over a crest. Flash your own high beams a few times and they can turn off their lights before coming over the crest blinding you.

The highway code disagrees with you. Flashing your headlights or sounding the horn should only be used to draw someone's attention to the fact that you are there.

Oh please. That's like citing the dictionary definition of a word which has come to mean something else.

The actual uses of flashing headlights are much more varied than the official version. For example "you are driving with your headlights off and it's dark", "you are blinding me with your main beams" and "a tree has fallen in the road ahead". I would wager that the unofficial version outweighs the official 10 to 1.

The only danger with flashing someone to give way is when there is potential for it to cause a conflict with other vehicles, for example a cyclist on your left. For that reason I always check my mirrors and slow to allow someone to cross in front of me rather than flashing them. Most people figure it out but don't completely disengage their own perception.

>In the mountains of Italy, drivers give a short honk before entering a turn on a serpentine road, which usually can't be seen around. If there is no responding honk, they will take the full width of the road (making the very tight turn easier and faster). Tourist drivers have to pick up on this :)

It seems like it should be illegal (and also partly suicidal) to go into the opposing lane in a situation where you cannot see if there is an approaching car. You're relying on someone in an opposing lane hearing and understanding your horn, for relatively little gain, and potentially fatal results.

Any situation where you can do everything 'perfectly' and you have a significant chance of dying or killing someone because someone else doesn't notice is a good situation to avoid.

If you hit someone's car under these circumstances it would be criminally negligent in my opinion.

Visit Italy! Just don't drive there.

These roads don't really have "lanes", it's more of a squeeze past each other kind of thing if you hear a returned honk: https://www.youtube.com/watch?v=VjPZhLiozAg

Being Italy, of course they do race cars down these roads :)

Even on racetracks indicators and high-beams are used in their own way (that is: if the race car is equipped with such lights).

Hazard lights (both indicators): Used in yellow zone, both to confirm to the marshals that the driver has seen the yellow flag. For drivers behind it is extra indication that yellow zone is ahead.

Indicate to the right: Acknowledge the faster driver behind you, indicating it is safe to pass. Also to acknowledge to marshal that the blue flag was observed.

Indicate to the left: Indicate to car in front that you are faster, please let me pass (same as blue flag by marshal). Obviously not used in competitive racing, but very useful recreational for track driving.

High-beams are sometimes flashed to thank/acknowledge marshal on a flag signal.

> Obviously not used in competitive racing, but very useful recreational for track driving.

While actual race cars don't have turn indicators, actual headlights are common in some racing classes (especially for endurance racing), and multi-class races are common (where multiple different categories of cars are racing on the same track, often with _very_ different top speeds). Flashing headlights is a common way for a faster car behind to indicate to the slower class of car ahead that they're coming.

In France they seem to use the horn, frantic (and frankly very rude) hand gestures and occasionally screeching tires to let you know that you did NOT in fact have the right of way entering the traffic circle.

In France drivers will flash their lights to warn you of police speed traps or other checks. (It's quite common for French police to stop and breathalyse all drivers on some rural road, especially on Sunday afternoons.)

I have driven in France loads and have literally never reached a police roadblock or radar trap without being warned by a vehicle coming the other way.

And just about as often to mean that you did have the right of way but they don’t care. Not limited to roundabouts, though.

I always hear/read about the speed trap warning. In motorcycle circles, IIRC tapping the top of your helmet is that same warning. I haven't ever actually seen either of those in practice, though.

Motorcyclists do usually wave at each other, or sometimes point at the road with a foot or two fingers, just as a greeting.

The one I do see (in the USA anyway) is flashing your high beams to let a semi truck know they have space to merge in front of you (eg after passing). They usually tap their brake lights a couple times to signal thanks after merging.

I feel like Waze has killed the high beams flashing warning, although I miss it. It sounds crazy as a say it out loud, but the signals between drivers always gave me warm feelings of some kind of community with other drivers. Now everyone on the road seems much more internally absorbed or focused. Cars are quieter, podcasts instead of radio, etc. While they were never very common, CB radios were also less rare in cars (we always had one for road trips and both my grandparents had one in on all the time in their cars).

what's waze?

A navigation app owned by Google, which is popular largely for its police and hazard notification system. Apple has recently copied this feature in Maps, and you can use Siri to report hazards/etc. (which I believe cannot be done in Waze, at least on iOS).

Some app that a small minority of people use which includes warnings about traffic, hazards, speed traps, etc.

There's two common motorcyclist signals for police: Either tapping the top of the helmet, or pointing up at the sky while moving your arm in a circle (to mime spinning police lights).

Other motorcyclist signs are sticking the left leg out to say thanks, holding your hand out and rapidly opening/closing it to say "you've left your indicator on", and pointing at dangerous spots on the ground like potholes, gravel, or other unseen hazards.

Flapping your arm like a child pretending to be a bird is another I've seen warning of a speed trap (it's actually the hand signal for "I'm slowing down" back in the days that was relevant).

Friend from Canada (who cycled from Vilnius to Warsaw) would give short honks to cyclists as some sort of appreciation or something. I thought it’s kinda annoying for cyclists!

Here in NZ will honk (or even call police) if you drive middle of the road - visibility behind corners isn’t great and tourists often confuse where they should drive. Whereas it’s fairly common to drive in the middle in Lithuania - sometimes it has better road surface.

I've seen this sort of comment many times, implying that indicators, flashing lights, use of the horn is unique to certain countries or regions. Yet every time, there's replies saying "hey I'm from <region not mentioned> and we also do this".

It seems to me people haven't realised the behaviour displayed in their part of the world isn't as unique or quaint as they think it is!

I'm in Zanzibar, TZ at the moment. Honking is also used when overtaking or in general to make others aware of your presence on the road (especially for pedestrians and cyclists). The interesting part though is with indicators. They use the right indicator (driving in on the left) to signal incoming cars to the vehicles behind you, meaning it is unsafe to overtake.

haha! we have to add a note in this thread, for which countries drive on the left and right. So your warning for passing signals are the same using the same logic.

They must not have cyclists in Italy...

I drive on a twisty road like that often, and I'd collect a cyclist every month if I did that.

They do, but having tried it, I wouldn't recommend it. If the cars don't get you, the stray dogs probably will. But don't worry, your bike will probably get stolen before either becomes a problem :-P

Okay, that experience (dogs, theft and dead cyclists) was actually in Sicily, not north Italy, which is very different in many ways, except for the driving.

When riding in a car with a long trailer (glider transport trailer) from Poland to Spain and back in ~2002, we quickly found out that LTV truckers would use indicators to point out when we gained enough distance when overtaking to safely merge back into the lane.

Flashing warning lights for thanks is also common in Poland.

>In much of Europe oncoming cars flash their lights to warn others about dangers and (especially) speed traps or police checks, so they can slow down in time. >Here in Lithuania, flashing your warning lights (the four orange ones on the corners of the car) means thanks,

Those behaviours are common in Ireland too

>If there is no responding honk, they will take the full width of the road (making the very tight turn easier and faster). Tourist drivers have to pick up on this :)

And self driving cars too, if they wish to reach full autonomy everywhere. But since currently they can barely keep themselves from crashing into obvious obstacles on the highway without human intervention, I think their prime-time is further into the distant future than pioneers like Elon would like to admit as I can't imagine they'd be able to handle the roads in Italy/Paris by themselves without an accident any time soon.

>And amongst truck drivers it's pretty wide-spread to blink right to tell a following car you think it's safe for them to overtake you and blink left when you think it no longer is

In India, the truck drivers blink right to tell you its safe (or want you) to overtake from right and they blink left if it's safe (or they want you) to overtake from the left.

Makes highway driving very confusing since a blinking left truck on highway means the exact opposite of city driving (YOU can go left vs I am going left).

yeah, self driving car is not coming anytime soon to India.

In India if we are ahead, and road is not straight, means a driver behind me can't see far, I will blink the directional blinker one or twice to tell him that its safe to overtake me now, from this direction.

A headlight flashes to incoming driver is saying, I see you want to overtake, don't, let me pass first.

A honk at sharp turns on going uphill, telling opposite traffic that I am heavy, cant afford to stop & then start, you give me way if required. There, there is a text painted (officially or informally) "Honk" or "Horn Please"

I remember when I first moved to Japan that my friends and I got off of our bikes and moved to the side of the road to let a car pass (it was a very small road). The driver honked as they went by, and the other American and I thought they were being rude. Honking in the US usually means, "get outta the way!" Our Japanese friend corrected us, telling us that two quick honks meant "thank you." I was blown away that such a thing existed!

apparently there was a time where there was an indicator on mostly larger vehicles for indicating takeover safety [0] (make sure you view the linked section).

I remember seeing a few of these (though never in use) when traveling in a country that still had a lot of old ladas - so i'm not sure it was only on trucks.

[0]: https://en.wikipedia.org/wiki/Automotive_lighting#Rear_overt...

When I visited Iceland, it seemed commonplace to flash your highbeams at the person in front of you if you intend to pass. It becomes the person in front's burden to signal a clear, safe pass. Kind of strange, and I can't imagine this system ever working in the USA. People can't even handle motorcycles lane splitting out of a "they're cutting in line" mentality.

We've taken to ringing our bicycle bells if we're approaching a corner or intersection we can't quite see past.

> Here in Lithuania, flashing your warning lights (the four orange ones on the corners of the car) means thanks, for example if you let someone merge from one of the very short onramps.

There's a similar custom in South Korea, where the warning lights are often used as a "thank you" if somebody lets you cut in front of them.

The same applies in southeast Asia/China/Japan, for both. It isn't exactly ubiquitous just in Europe.

Not in USA though.

Other than trucks blinking left or right, all of these are pretty common in the US.

As someone who grew up in a rural area, honking before going around turns on small roads or crossing single-lane bridges you couldn’t see the other side of was something we did regularly to avoid being hit.

I don’t experience this as much in larger cities though.

In Sicily in narrow crossings where you don't have the right of way but cannot see you can slowly inch forward, and if someone is around the corner they will honk at you to let you know to wait.

> As someone who grew up in a rural area, honking before going around turns on small roads or crossing single-lane bridges you couldn’t see the other side of was something we did regularly to avoid being hit.

I've never found this in rural Indiana, but I wish it were common practice. I've found people often simply assume no one is coming because there are so few cars on the back roads; very nearly experienced a head-on collision approaching one curve a few years ago.

My father said honking is common going around corners on small roads in the mountains in Columbia.

I don't see those signage on cars in the USA, but there are a few places where cars are explicitly told to blow their horn, example: https://goo.gl/maps/WWC4ACVRdeyUQnZ57

Also in Lithuania: it is forbidden to use hong in urban areas unless it is to prevent an accident.

Signalling your presence for safety is pretty much the only legitimate use for a car horn, so that makes sense. Of course, the part where they take up the whole width of the road kind of then causes a bunch of added risk...

In Upstate New York where snow drifts can sometimes completely block visibility at intersections, honking is pretty common as if to say "ready or not, here I come!"

"Tourists have to pick up on it" seems like a strange thing to bet one's life on.

Does making the very tight turn faster get one home much quicker? Why not just slow down?

> "Tourists have to pick up on it" seems like a strange thing to bet one's life on.

Tourists are generally advised to pick up on local customs. I used to live in Amsterdam. Cyclists expect pedestrians to hear the bell ring once and get the hell out of the fietspad. If you don't, you will get hit.

> Does making the very tight turn faster get one home much quicker?

In Italian Alps where you spend half the time turning? You bet!

> Why not just slow down?

Have you met many Italians? :)

> I flash them a grateful hand sign when passing their mirror.

You'd probably use the warning lights for this in Germany. At least with truck drivers this is a common thing.

A person know that spent time in Japan (I think, back in the 70's) mentioned while stopped at a traffic light, everyone would turn off their headlights.

> In the mountains of Italy, drivers give a short honk before entering a turn on a serpentine road,

This was common in Puerto Rico when I visited.

Flashing the warning lights also means "thanks" in Ireland.

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