The key detail is that, like with rear brake lights, they extinguish when the foot is removed from the brake pedal. So it's not so much the presence of the brake light, but the presence of an inactive brake light that would, serve as a warning that a car is about to start moving. This would be very helpful to drivers on a road when other drivers are pulling out too early from a side road or driveway. That little bit of extra warning is, in many situations, enough for you to pump the brakes, hit the horn, or both.

Risk Compension predicts that drivers would simply use this new information to drive more aggressively, negating any possible safety benefits.

i don't think that was ever required in the US. it is elsewhere though.

okay, pick a different color then. it's a solvable problem.

I have, and that's my point.

I'm a lowly drone pilot that isn't really made to understand what those lights mean but did out of my sheer curiosity.

But the average pedestrian is going to take some, teaching?

and honestly i have the same problem with that intended use. it often looks like a stopped car is attempting to turn out into traffic. IMO emergency lights should have a faster blink pattern or something to differentiate from turn signals.

for example, say you are waiting to make a left turn, it would be nice to know if oncoming cars are braking or not. if they are stopped and you see their brake lights turning off, you can judge if you should hurry up or not turn at all.

Can't speak to "required." But I know it used to be done.

And never forget about the I-D ten T error.

But isn't that exactly the situation we're in now? If there's a car in the opposing left turn lane, they might start to turn in front of you.

The only thing the light does is say "right now, they're braking". It doesn't say whether they're moving or stationary any more than the headlights, and it doesn't say anything about their intentions or whether it's safe to enter the intersection.

Struggled with this for a second, then I figured it out...

The brake light coming ON isn't the important part, like the rear brake lights... it's the brake lights turning OFF that's important in the front.

So maybe, now hear me out, MAYBE we need to invert that. Have front brake lights that are on ALL the time, and pressing the brake turns them off to indicate safety?

Yeah, and then you have the distraction of people looking in the mirror because of lights behind them. Especially seeing lights behind you at night thinking it’s a police car

ID10T for those who didn't get it.

First of all, this would be illegal in many countries.

Second of all: we can differentiate cars by: has red lights, back.

If we lose this option we can no longer differentiate easily if there is a car coming towards us or driving away from us.

Say you're a pedestrian and a car is coming toward you as you're entering a crosswalk. Being able to see if they are braking or not could save your life.

Isn't that the case for pretty much everything? Newer cars alternate blinking their headlights and the signal indicator, and even cars w/ the turn signal on the side will have some light bleed through since it's all one assembly. In the majority of cars, I can see their turn signals when they're perpendicular to me. The larger issue is that most people in my area don't bother to use their signals in the first place.

I've seen newer cars turn the headlight off while the turn indicator is on, so you get a sort of double-blink effect.

I don't see any reason why we can't just have the whole headlight blink yellow as well with the turn indicator. LEDs are everywhere and can handle changing colors really easily, so it's not hard to require that for all new cars.

I still think rear signaling could be improved dramatically by using a wide third-brake light to show the intensity of braking.

For example -- I have seen some aftermarket turn signals which are bars the width of the vehicle, and show a "moving" signal starting in the center and then progressing towards the outer edge of the vehicle.

So now take that idea for brake. When you barely have your foot on the brake pedal, it would light a couple lights in the center of your brake signal. Press a little harder and now it's lighting up 1/4 of the lights from the center towards the outside edge of the vehicle. And when you're pressing the brake pedal to the floor, all of the lights are lit up from the center to the outside edges of the vehicle. The harder you press on the pedal, the more lights are illuminated.

Now you have an immediate indication of just how hard the person in front of you is braking. With the normal on/off brake signals, you don't know what's happening until moments later as you determine how fast you are approaching that car. They could be casually slowing, or they could be locking up their wheels for an accident in front of them.

Yea, that's part of why I don't know for sure if they make cars the way the guy at the top of this thread is describing.

Same. I don't think I've ever seen a car that can show me the signal on the opposite side of the car, but I have seen a lot of cars where I can see the indicator while stopped at an intersection and the car is perpendicular to me, since I have a little bit of angle to see the edge w/ the indicator.

99% of the time, it's not an issue, and the other 1% of the time it doesn't really matter if I can see the indicator (I.e. they're already halfway turning, so they're angled away from me).