[kbuck]

In California (and most places I've lived), this is actually legal. To complete the turn, you first enter the intersection while the light is green, then wait for traffic to clear. If it only clears after the light turns red, you're still in the right - because only when you fully entered the intersection (on the green light) is considered. See here: https://patch.com/california/sanbruno/ask-a-cop-should-i-pul...

Of course, this only allows one car (or maybe two, if the intersection is particularly large) per light cycle, which isn't much. People who enter the intersection on the yellow or red light (tailing the person who was in the intersection waiting to turn left) are turning illegally.

[friendzis]

In my country there is very specific provision along the lines "it is illegal to enter intersection if an obstacle would force a stop in intersection and block traffic" which means that in a "turn left or go straight" lane you enter intersection and cannot turn left due to traffic and block traffic for cars going straight making that technically illegal. Human drivers, of course, do this all the time.

[usrusr]

Are you sure that moving, oncoming traffic is seen as an obstacle under that definition?

The real trick against gridlock is to equate the switch to green not as "go", but as "go, once the previous wave has cleared the intersection". The "don't enter before there is room for your car on the far side" is only an optimization on top of that.

[friendzis]

I am not a lawyer so I may not be 100% correct. As far as I remember my driving classes and other resources (cannot quickly find exact provision), anything that is not part of road infrastructure (there are intentional obstacles to guide traffic) and causes vehicle to change speed/direction is an obstacle, so moving traffic kind of is. I understand that this particular provision is specifically there to prevent gridlocks and is never enforced in this particular situation.

The way traffic works is somewhat dependent on region. I can go to another city an hour away and already feel a bit alien traffic wise there. This is relevant in discussion on autonomous vehicles: in any foreseeable future we need them to coexist with human drivers and abide by unwritten "everyone drives like that here" rules.

[xeromal]

If you come to LA, you'll see there's no way to avoid it. The majority of lights are unprotected left turn lanes. The cops here even break the laws and no one judges. Sure, everyone could make 3 right turns instead, but I'd imagine if everyone did that the damage from wasted fuel, smog, and extra traffic would outweigh the few accidents that happen due to cheating the left turns.

[ghusbands]

In situations in which my country has that same provision, it does not treat moving traffic that crosses your path as an "obstacle", so if you're turning across traffic, you're allowed to enter the intersection and wait there. It might be worth double-checking whether your country has a similar subtlety.

[WillPostForFood]

You are allowed to enter the intersection on yellow in California.

21452. (a) A driver facing a steady circular yellow or yellow arrow signal is, by that signal, warned that the related green movement is ending or that a red indication will be shown immediately thereafter.

[DrScump]

But CA law also says you can't enter an intersection without having clearance to vacate it. In other words, if the cross street itself is backed up such that its traffic backs up or into that intersection and prevents you clearing the intersection as you complete the turn, you violate the "anti gridlock" law.

[WillPostForFood]

That's not relevant to this situation. Waiting for oncoming to traffic to clear, then turning while the light is red is legal, and orthogonal to whether "there is sufficient space on the other side of the intersection". If there isn't sufficient space to turn, whether the light is green, red, or yellow, then you can't turn and are violating the anti gridlock law. If you entered the intersection before it turn red, and there is space to turn, you can turn on green, yellow, or after it turns red.

[joecool1029]

Most jurisdictions do not consider it blocking the box if you enter the intersection to turn and it turns red after. They consider it blocking the box if you enter with the intention of going straight while it is not clear to do so.

This is the case for NY state, see VTL 1175: http://www.safeny.ny.gov/rowa-vt.htm

[DrScump]

CA Vehicle Code 22526(a): "Notwithstanding any official traffic control signal indication to proceed, a driver of a vehicle shall not enter an intersection or marked crosswalk unless there is sufficient space on the other side of the intersection or marked crosswalk to accommodate the vehicle driven without obstructing the through passage of vehicles from either side."

https://leginfo.legislature.ca.gov/faces/codes_displaySectio...

[romwell]

This does not seem to be relevant to the situation here (waiting for the oncoming traffic to clear): usually, there's plenty of space to turn into, but one has to yield to oncoming traffic before occupying that space.