In the Bay Area we have mostly left turn lanes, and they frequently have left turn arrows to allow both directions to turn left while the thru lanes in both directions are stopped. A green arrow means it is okay to turn, clearly the opposite of that is a red arrow. These turn only lanes don’t have ball signals, since you don’t want to imply that is okay to go straight in one. The intersection I mentioned has right arrows for right turn only lanes. These aren’t nearly as common.
What did Rumor_Watkins post that brought you to believe he was saying it’s sometimes okay to blow through a red light?
The best I understand is that they want the arrow in the turning lane to emphasize that it is a turning lane, cannot proceed straight. Why the red has to be an arrow, too, is, I guess, to tell you it’s turn only even while red so you can preclude getting in the wrong lane. Even though there are signs and paint that do that job.
In Arkansas, Oklahoma, and Texas, I do recall encountering a left red arrow. That would signal you are in a turn lane and must stop. If you are in a lane that has a protected turn time period, then an unprotected turn if traffic allows period, they have a green arrow, a yellow arrow, then a green ball, yellow ball, red ball.
Someone might assume the ball means it is no longer a turn only lane. Against the signs and paint on the lane designating otherwise.
I am familiar with left turn arrows and how they work, but a red left turn arrow is never needed. The left side of this diagram is how I see is the best way.
Red means stop (obviously), a green ball says you must yield to traffic to turn left (just like if you were at a 1 lane intersection), and a green arrow means you have a protected left. Apparently, the driving public is too stupid to get it, they think the green ball means protected left just because you are in a left turn lane.:smack:
Not really, there is a very good use for red left arrows, and it’s mostly the same reasoning for red right arrows.
The intersection may be designed in such a way that it is dangerous enough to make an unprotected left, so they want to prevent those turns while the rest of the intersection can go straight or right. This is particularly true when you’re turning left onto a very wide street, and your street has only a few lanes, so you have a lot more distance to cover when turning left.
If you live in a city that isn’t on a grid, intersections are not neat and tidy - they’re sometimes very gangly, the road will turn as you are going through the intersection, etc that can make it a dangerous turn.
It could also be done where there is such heavy traffic that there aren’t enough breaks in the opposite straight-through traffic that people will routinely get stuck in the middle of the intersection, waiting for a hole in which to turn left, which will only enhance gridlock as they will still be stuck as the light changes over.
And while you must watch for pedestrians in all cases, a circle-green is exactly when pedestrians are given the go-ahead to cross. If you couple that with 2+1 (or more) lanes to cross and with the left-turner focusing hard on the on-coming traffic with which he/she is about to play Frogger, then you have a dangerous situation. (“Wait… wait… okay, I can squeeze though… Floor it! vroom Oh crap, a person!”)
In my area, there is a mix of red arrows and not, and it’s always the wide, busy, ped-heavy intersections where the red arrows are found. (There’s one important and busy intersection where one of the left turn lanes has four states: green arrow, red arrow, yellow arrow, and flashing yellow arrow, the last of which serves as a solid green circle but still with the visual clarification that you can’t go straight.)
Yes, the big intersection near me has two left turn lanes and three through lanes. The left turn lanes have green and red arrows. I assume that there is data showing that inevitably people will misjudge the time they have for the left - especially if multiple people try to make a left turn on a green ball.
This intersection also had a ton of red-light runners before they put up a red light camera. Now they are very rare.
The left side of that diagram is screwed up. Is it for one lane or two?
There are plenty of places where there is one lane of traffic (sometimes with an additional right turn lane) where left on green if safe is the rule. These don’t have left turn arrows. I’m talking about left turn only lanes.
We make legal turns on red all the time here in Michigan; but only because we “invented” the Michigan Left concept for making intelligent and safe left hand turns. 
Not like those people in Pittsburgh who scared the hell out of me when I saw what they did for making left hand turns. :eek:
I’m sure you know this, but for the sake of accuracy, it’s illegal to turn right on red on theentire Island of Montreal, not just the city. You generally know when you’ve left the Island due either crossing a bridge or driving through a tunnel. When you come back onto the Island, there are helpful signs on the bridges and tunnel reminding you that you cannot turn right on red. Despite it’s name, the West Island is not it’s own island, but is rather the western end of the island.
Besides, it’s all one-way streets that go left when you need to go right anyways. You can’t get there from here. Go back, park and take the metro. 
Or, “I might not be able to turn right on a red light, but tabarnak I can go right through it!”
I have to correct myself. I have seen left turn red arrows - spotted one just the other day at an intersection I use frequently. That shows my attention span. So they have been making progress into the area.
Yes, the intent is to apply them to left turn only lanes to emphasize the lane is stop for the left turn while whatever else is going on occurs. I could see a double stack like that left picture where there’s a red left arrow and a green straight arrow on a lane that is not left only, but has left or straight.
Screwed up how? Because it has two short stacks instead of one long stack to apply to one lane? I’ve seen that arrangement. The progression starts green arrow, then yellow arrow above, then down to green ball on the green line and a yellow ball on the yellow line, then a single red ball at top. Signals the driver when left is protected vs when left is yield to oncoming traffic. It is fairly efficient.
Placement of the light over the single lane usually clarifies where it applies and where it doesn’t (the other lanes, that have their own lights).