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Comment by UseofWeapons1 | Hacker News Reader

I had to look this up. In California in particular, this is true, which surprised me.

Per a random law firm: California’s yellow light law permits drivers to enter an intersection during a yellow light. No violation exists unless any part of the car is over the stopping line when the light turns red. However, the law encourages drivers to slow down before reaching the intersection.

Whereas in, for example, Massachusetts, this would be considered running a red light.

https://www.wccbc.com/red-and-yellow-light-accidents/#:~:tex....

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If this surprises you, consider the alternative: Driving through a yellow being illegal or unexpected doesn't make sense, given the finite stopping distance of cars, and reaction time of humans. This is because the yellow light is the first explicit indicator you must stop.

If this doesn't make sense still, picture this scenario: You are driving at the speed limit. You are 500ms from crossing the stop line threshold. The light turns yellow.

Your interpretation would make sense only if there were a (paler yellow?) light warning of the yellow light!

Yep, something something Chesterton's fence. If you couldn't drive through a yellow then you effectively have two lights go/stop which makes drivers choose between the safe but illegal thing of running the light or the dangerous but legal thing of slamming on their brakes.

You can't have an instant switch between go/stop which yellow— effectively meaning unsafe stopping distance go, safe stopping distance stop— solves very neatly.

> effectively meaning unsafe stopping distance go, safe stopping distance stop— solves very neatly.

That's how it works in Poland and it works reasonably well.

On the other hand when light is about to turn green, yellow lights up. So red and yellow at the same time means prepare to go.

In France, it is illegal to drive through a yellow light unless it would be dangerous to stop, for example if it required you to break hard. That part is up to the officer judgment.

In practice, I have never seen it applied, and it is only a small fine anyways, much less serious than running a red light. I guess it can be used as an excuse if the police really wants to pull you over.

Austria does that: 4 seconds of the green light flashing in order to announce the yellow light.

So a pre-yellow light? This seems like you just changed what we call a yellow light to the 4 flashing greens, and made the yellow the new red. If yellow means “don’t enter the intersection”, how is that different than a red?

With this change to the scenario, being required to stop before yellow makes sense. And blowing through red means you extra screwed up! (?)

On this note: In the UK, there is a yellow light prior to green; love it.

The US sometimes has something similar: visibile countdown timers for the pedestrian crossing turning form stop to go, which coincides with the car light turning from red/stop to green/go.

This encourages people to run the light by trying to turn exactly as the countdown timer hits 0, trying to race against pedestrians trying to cross crossing pedestrians.

You could always do that before in most instances just by watching for the yellow on the cross street too. Though I think the green is often slightly delayed relative to the pedestrian light, precisely to ensure the car cannot win that race legally

How long until we can get a proper countdown like some pedestrian signals have?

On the contrary, I think it could make perfect sense: What's written in the law is one thing, and how it's enforced is another; I would argue that the former should be done with consideration to the latter.

Based on my own experience, I'd estimate that well over 99% of traffic infractions go entirely ignored by the law: minor speed violations, unsignaled lane changes, rolling stops at stop signs, expired tags, cell phone usage, and yes, running red lights.

When the letter of the law is broader in scope or errs on the side of caution, that enables the police to exercise their judgment in enforcing it (with the obvious caveat that some police will abuse any power you give them). You could imagine a scenario where someone technically runs a red light but it's totally justifiable and safe (heavy load + moderate speed + short yellow + no other traffic) and another where someone technically makes it into the intersection on a yellow light but senselessly severely endangers public safety (busy intersection + rapid acceleration + traffic backed up on the other side of the light).

I would be okay with someone evading a ticket in the first case and getting one in the latter.

In the UK, if you're at all over the line when the lights change, you're considered "in the junction" and are expected to leave the junction -- the next phase should give you priority to do so. The only way to run a red light is to start crossing the line while the light is red -- although plenty of drivers will start to inch across while they're supposed to be waiting :P.

The most annoying scenario is where a driver has either stopped or inched forwards far enough that they can't actually see the lights any more and don't know when they've changed.

This is the law in Illinois, too. It, in combination with the way the lights are timed, makes some intersections particularly challenging for pedestrians.

The basic way the timing goes is: traffic light changes, pedestrian crossing signal illuminates, traffic going straight that squeezed in on the yellow finally clears the intersection, cars turning left finally get a chance to go, pedestrian can finally safely enter the intersection with approximately 10 seconds left to cross a four lane street, lights change again, cars start honking at the older person with mobility issues who could only get halfway across the intersection in the time they had available to safely do it, impatient driver from further back in the line who doesn't care to figure out why the person in front hasn't started moving even though the light has been green for five full seconds swerves into the right turn lane and guns it, narrowly missing the aforementioned older person with mobility issues as they blast through the intersection.

I'm wondering how you would know when the yellow light was going to come on.

Do you have some sort of countdown, or innate knowledge?

Because, otherwise do you just randomly stop at green lights guessing that a yellow light might come on? Or do you drive so slowly that you can stop in the width of the white line before a pedestrian crossing? Really, I'm trying to figure out how you don't ever enter just as a light turns yellow. Once you do, do you stop in the intersection or try to clear it before it turns red? I hope the latter.

For me yellow lights are a warning that a red light is coming. It should be long enough for cars to clear the intersection (in many states without gridlock rules even this is not the case for left hand turns).

My experience in Boston is that drivers try to beat the green light change and accelerate while it's still red.

> For me yellow lights are a warning that a red light is coming

Correct, yellow means "start slowing and stop before the intersection if you can do so safely, otherwise proceed". Red means "do not proceed if you aren't already in the intersection".

This is why the opposing traffic signal and walk signal will wait for a second or two after red: to allow people who entered on yellow to finish their transit across the intersection.

Indeed, in the author's own video where they incorrectly claim someone ran a red light, the author had no legal right to cross anyways, so there was no chance of the author getting injured unless they ran a red light at the crosswalk.

In short, the author seems most frustrated that the situation changed from everyone waiting on him, to him waiting a few seconds for others.

> Do you have some sort of countdown, or innate knowledge?

often, in the form of the pedestrian signal.

> try to clear it before it turns red?

This is the rule in much of the world, yes.

I assume you mean the perpendicular direction crossing lights? Most pedestrian lights have delays longer than that in California for safety so you might stop at a green light.

Also, if nobody presses a button ped-lights don't even turn on, just like left turn signals don't turn on without a vehicle triggering it.

> Also, if nobody presses a button ped-lights don't even turn on

This is no longer true in many cities. Most SF crosswalks don’t require a press anymore, many don’t in LA, and all don’t in New York. AFAIK it was a Covid thing, back when people thought surfaces spread the virus, but it stuck.

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