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Comment by jondwillis | Hacker News Reader

LA has an unwritten law where 2-3 cars make unprotected lefts after oncoming traffic has cleared on yellow/red lights. Letting FSD drive, it can’t honor this “cultural” (technically illegal) behavior. If I am operating it, off goes FSD in that moment.

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Tesla has been specifically reprimanded by NHSTA for allowing FSD to drive like human rather than to the letter of the law. The rolling stops is one I remember, but basically it'll apply to anything.

Dude it's totally following the law. You're allowed to enter the intersection for an unprotected left even if it's not clear to turn (possibly not if the end of the intersection you're going to is full of cars). If you are in the intersection, you're allowed to clear when possible regardless of the color of your light.

Most intersections with unprotected left turns let you fit at least a whole car, sometimes two in the intersection to wait, and the third car has its front wheels on the paint, so it's totally in the intersection.

While you are allowed to enter the intersection during a yellow, you are also considered legally to have been warned and would be consider liable if doing so causes an accident.

This extra liability would seem like making self driving cars error on the side of stopping to be in the interests of auto makers who would be exposed to that liability.

Incorrect. As long as your front wheels pass the stop line prior to the light turning red, you are legally driving through the intersection and should continue and clear the intersection on the other side (not stop in the middle).

Imagine how crazy the law would be if this were the case: - Light changes from green to yellow 1ms before your front wheels pass the stop line - Other direction traffic runs a red light and hits you from the side - You're now somehow liable because your wheels entered the intersection with zero ability to react quickly enough (no human can react in 1ms and no car can stop that fast) and the other driver that clearly blew a red is not?

That would be pants on head crazy, tbh...

Mostly the cars will have entered during the green, not the yellow, and were waiting for a chance to turn. When there was no opportunity to turn while the light was green, they must turn while the light is yellow or red, because they are already in the intersection and must clear the intersection.

How would entering on yellow cause an accident?

Correct. The law states that as long as your front wheels are in the intersection prior to the light turning red, you should proceed through the intersection. Inexperienced drivers that either stay in the intersection or try to reverse into traffic behind them are breaking the law and create a huge hazard for others.

Even if the light for opposing traffic turns green while the turning car is still clearing the intersection, opposing traffic is legally required to wait and not enter the intersection until opposing traffic has cleared the intersection.

It’s legal to turn left in such a case as long as you entered the intersection already. So at least the first 1-2 cars are not doing anything illegal

You can't legally enter an intersection (advance past the stopping line if present) until you are clear to perform your transit of the intersection. Left on red is never legal and marginal on yellow.

> Left on red is never legal and marginal on yellow.

Not parituclarly relevant to the gridlock violation at issue here, but left on red from a one-way street to a one-way street is legal in the same conditions as right-on-red generally in a large majority of US states, a few of which also allow left-on-red from a two-way street to a one-way street. Left-on-red is only completely illegal in a few states.

The law here is clear. There has to be "sufficient space on the other side" before you enter the intersection. There is no need to make the entire maneuver at once.

> You can't legally enter an intersection (advance past the stopping line if present) until you are clear to perform your transit of the intersection.

Yeah, I've seen tickets written for this in Emeryville, CA for cars that entered on green and weren't going to clear the intersection in the next ten minutes. (I don't know if the intersection is still that bad.) Bicycle cop, because there was no way they'd get a car in there.

> Left on red is never legal

I recall that this was legal in Michigan, where I grew up, but it either had to be onto or off of a one way street. I could never remember which, so I didn't try it.

But I did see someone make a left on red on market street in SF from the rightmost lane, which is very illegal.

> I recall that this was legal in Michigan, where I grew up, but it either had to be onto or off of a one way street. I could never remember which, so I didn't try it.

I believe it requires two one-way streets.

Yeah, this covers the case when turning left doesn't cross any oncoming lanes of traffic - so it's basically the same as turning right on red at a normal light.

Although searching for this now, it does appear to also be allowed from a two-way,[0] which sounds vaguely familiar but isn't really the same as turning right on red.

[0] https://www.michigan.gov/msp/services/traffic-safety/traffic...

Yeah, but sometimes the second and usually the third (and fourth - I have seen it!) are not in the intersection.

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