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Comment by ozgune | Hacker News Reader

I've been driving in the US for 16 years. The "left turn on green" is still the most non-intuitive part about driving here.

As a driver, when you have a green light, you need to pay attention to giving priority to incoming traffic and pedestrians crossing the street, while also maintaining your calm with cars lining up behind you. It's way more intuitive that when you have a green, you can go.

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In a few US cities they have what is called a 'lag left' where the left turn lane gets a green left arrow for several seconds after the straight lanes turn red. This has the benefit of having left turns occur when pedestrians should not be crossing the side street at the cost of some spectacular head on collisions when drivers run the red light.

NYC and a few pedestrian heavy areas have actually started doing the reverse; delayed lefts.

The idea is that pedestrians, cars, etc. get a headstart so that by the time the left is legal, any people or vehicles crossing will squarely be in the middle instead of to the side where they could be blocked by a pillar.

Not even just lefts; in SF now most[0] lights will show a pedestrian walk sign around 5 seconds before any light in that direction switches from red to green. So pedestrians will have a chance to make themselves seen before cars do anything.

It's also useful if you're a pedestrian going in the perpendicular direction. If your light turns yellow, you still have another 10 seconds to get across (5 seconds for the yellow->red transition, and then another 5 seconds before the opposing light turns green). Granted, this isn't universal (see below), so you still need to pay attention and sometimes hustle across.

[0] Weird that it's not all, but I still see many that turn simultaneously still.

Lefts in drive_on_right jurisdictions are privileged because they cross lanes of traffic. Privileged means they have to have priority on signal change - start and stop. In driver's Ed, it is taught that the first queued vehicle making a left turn can take it even though a light may have just turned to red when the opposing traffic has stopped. Similarly, a left turn signal is activated before the through signal to allow any queued left to turn and provide a gap to the traffic behind it to turn to any right lane if additional cars become queued in front unable to make the left turn. Further, drivers cannot be expected to keep track of and attempt to predict the movements of a crowd of people, only avoid hitting obstacles in their direction of motion. If any pedestrian cannot get across in 5 seconds, then a change to green on the parallel vehicle traffic lane could be mistaken as absolution from liability. The point is to reduce confusion. At crosswalks, pedestrians really only have one rule: Don't run out in front of a car, making it impossible for the driver to stop in time. Any start "delay" along with accelerated stop should occur on the pedestrian signal as people do not move in single file "lanes", but rather as a group that is able to handle a decreased queue elimination time with the expectation that the duration of the parallel through green is long enough for all queued pedestrians to cross.

> Privileged means they have to have priority on signal change - start and stop

Citation needed. Traffic laws vary widely based on the jurisdiction.

> If any pedestrian cannot get across in 5 seconds, then a change to green on the parallel vehicle traffic lane could be mistaken as absolution from liability.

No, if you hit a pedestrian in the crosswalk and they have the green, the driver would be at fault in a jurisdiction like NYC.

In Norway, you Are never allowed to enter the intersection on a red light. If you want to turn left, you move into the intersection when the light turns green, then stop if needed. At that point the light doesn’t matter to you anymore, and you proceed once the way is clear. With heavy traffic in the opposite direction, that often means after the light turns red.

Thats pretty much the same situation as over here, in Austria. Police is perfectly fine if you drive out of an intersection when it is red. But driving into it when it is red, can incur a HEFTY fine.

Also: A arrow on the signal means you can just go, a full blob means you have to be careful about other traffic.

So we have a few intersections where left turns are on a different timer, where ONLY the left turning traffic goes. Usually before the head on traffic gets green. Or where the arrow extends it for the left turning traffic, so they still are allowed to drive into the intersection when straight on wouldn't.

I think you and the person above you are talking about the same thing.

They're different things.

the parent comment is describing a scenario in which

straight (including pedestrians have green) -> straight gets red -> left gets green.

in NYC's LPIs, this is

all directions have red -> pedestrians get green -> straight + left get green with pedestrians

I have seen that quite often (green arrow after red for straight lanes) and had assumed that was pretty common, but I don't really know for sure.

Regarding collisions due to people running red lights: at least when waiting to turn left chances are very good that you will see the oncoming vehicle since you're already pointed towards them.

That seems much better than being first in line at an intersection when the light turns green; in that case anyone running the light may well be coming from the side. I lived in Dallas for a few years and after a few near misses I learned to always look before proceeding after the light turns green.

You can fail a driving test in Australia if you don't look whilst being first at the lights on a green light cycle.

Of course most drivers might do this for a week after getting their license then ignore it. Like a lot of good rules.

> at least when waiting to turn left chances are very good that you will see the oncoming vehicle since you're already pointed towards them.

That's only true if there are no oncoming cars lined up to turn left in front of you. Even just one car waiting can obscure an oncoming car coming around them to run the light and crash into you as you turn.

There are some intersections like this in my city, but I've seen some drivers blow straight through the red light in the straight lanes because, presumably, they are barely paying attention but see a green light in their peripheral.

Arizona is like that.

This is for California, not sure about other states:

Note that whether you have a solid green or a green arrow matters. A solid green means you can turn left, but you might have cross traffic. A green arrow means you're protected and as long as other people are obeying traffic signals, you shouldn't run into other people.

Lots of drivers don't understand this.

Lots of drivers also don't understand a red right arrow (as opposed to a red solid circle) means you cannot turn right on red. Most "no right on red" intersections have both the arrow and a sign (and many drivers ignore both).

I've always thought the differences between the solid light and arrow was too minor for the average driver. I mean, look at the skills of the average driver.

In Washington state unprotected lefts weren't legal maneuvers for quite a while. They were introduced gradually starting at intersections where it would be a traffic benefit, for signaling the state adopted a blinking yellow arrow that then goes solid to signify the 'almost over' meaning of a typical yellow light.

One thing common in Texas is red light + green arrow to indicate a protected left/right turn. I suspect it's a lot easier to parse quickly for most people than green circle vs green arrow.

Is it? I see people sitting stopped at green arrows all the time because the red stop light takes priority in their mind. Presenting clearly contradictory signals at the same time can't be the best option.

Yeah honestly I'm not sure how would I take that. Maybe expect it to be a malfunctioning light? When presented with both 'stop' and 'go' you can bet I'm not going unless I explicitly verify that nothing is coming.

Really? The grandparent says it's common in Texas, but in my experience it's pretty common in all of the US (at least in urban and suburban areas), and shouldn't be surprising or odd to anyone who's learned to drive in the US or has been driving here more than a few months.

But I agree with you that you should verify that no one is coming in that case; that's sound advice for most all situations, really.

It may be a kneejerk reaction combined with me being very rurally located for work for these past 4 years, I think there are 3 traffic lights within a 45 minute drive and none of them will show red and green at the same time except in separate lanes when straight is red and left has a green.

The protected left should be the middle yellow with an associated cutout for the left arrow inside the light, with the normal through yellow turning on both the green and yellow left turn arrow, but likely way too many years of convention to make the change.

Are you referring to the traffic signals that have five options? That is, going clockwise starting at bottom left: green arrow, yellow arrow, standard red light, standard yellow light, standard green light

https://i.ytimg.com/vi/8MXdKQHddMk/maxresdefault.jpg

> a red right arrow ... means you cannot turn right on red

This varies a lot by state. Several allow turning (after a stop) on a red arrow. Some even allow turning left on a red arrow, if it's onto a one-way street.

https://driversprep.com/red-arrows-permit-practice-test/

That's seems unnecessarily confusing. Why even bother with the red arrow at all then? I guess it could be useful in cases where the straight-through traffic is green, but you want right-turning traffic to stop before turning, but is that common? Or even a useful thing? Like, I feel like if you've set things up that way, maybe the intersection is just designed poorly.

It is definitely confusing. In Washington state, right red arrow does not prohibit turning on red. I learned this after people started beeping at me to go at such an intersection. And yes, that intersection (Queen Anne and Mercer in Seattle) is confusing and poorly designed.

I don't think I've seen many intersections with red arrows unless there is a dedicated turn lane, where green yellow and red are all arrows. If it's a right turn in a right on red jurisdiction, without a sign expressing no right on red, why would red arrow be different than red circle?

MA allows right on red arrow after stop (absent a sign to the contrary). There are intersections where right on red is prohibited to protect a pedestrian walk phase that’s aligned with the green for straight ahead traffic.

> A green arrow means you're protected and as long as other people are obeying traffic signals, you shouldn't run into other people.

> Lots of drivers don't understand this.

This is logical. But, I've seen firsthand in Quebec (the city of Sherbrooke) where that's not the case. A driver may have a green arrow at the SAME TIME that a pedestrian has a walk signal. And in St. Thomas USVI I've seen opposing traffic have conflicting signals too (green arrow at same time oncoming traffic has green to go straight!)

I've lived in multiple states including California, and this is the first I've heard of red right turn arrows meaning no right on red. Good to know.

I believe I've also seen red right turn arrows in Pennsylvania, but they don't have any special meaning there. But I couldn't say for sure.

Huh, interesting. I've also lived in multiple states including California, and I've always understood a right turn arrow to mean no turn on red.

I wonder where the driver education here is breaking down.

Learned to drive (a long time ago) in PA and now live in CO. You’re right it’s all weird.

In PA, red arrow is just a regular red light that happens to be in a turn-only lane. All laws are the same as normal red light, the lane marking restrict your movement.

In CO, red arrow means stop and no turn on red regardless of lane markings.

Just about all traffic control laws are standardized federally except lights. That feels like the most important one to reduce confusion.

> Lots of drivers don't understand this.

Not sure I believe this. Obviously it's a fuzzy statement but I don't think I've ever once in my life seen someone blatantly ignore oncoming traffic due to having an unprotected left signal.

Any one driver's experience is necessarily extremely limited, a tiny fraction of a fraction of a fraction of all miles driven or traffic lights stopped at. You not having seen that happen should not be expected to be representative at all.

I have seen that happen, though fortunately there was enough time for both drivers to avoid a crash.

> Note that whether you have a solid green or a green arrow matters. A solid green means you can turn left, but you might have cross traffic. A green arrow means you're protected and as long as other people are obeying traffic signals, you shouldn't run into other people.

This is the same in the southeast, and I assume the rest of the US.

Recently "flashing yellow" [1,2,3] has been introduced to mean left turns must yield to right of way traffic. These are gradually replacing solid green signals.

[1] https://www.txdot.gov/driver/signs-and-signals/flashing-yell...

[2] https://durhamnc.gov/1140/Flashing-Left-Turn-Arrow-Informati...

[3] https://www.penndot.gov/TravelInPA/TrafficSignalsManagement/... (PDF)

This is confusing, generally a blinking yellow when going straight means slow down but you have right of way. A blinking left yellow would be different from a normal blinking yellow.

Yeah, it should probably be a blinking red arrow in order to be consistent. I'm sure some committee decided that wasn't different enough from normal red arrow

isn't flashing red a fail-safe triggered when the light controls fail that should be treated as a stop sign?

In practice that might work, but it's also a conflicting signal.

Blinking red would be a stop and proceed when safe sign. There’s no reason for each car to stop for a lot of these unprotected left turns.

This varies somewhat based on locality. In Oregon, for example, there is no special significance to a red right turn arrow. If a right turn on red is not permitted, there will be a sign.

I agree. Left turns on green are an invention that works great in rural American small towns where traffic volume is low. Most of the places I've lived transition to protected signals as the density of the area goes up, but sometimes it can take years for the funds to be allocated, and in that time it can become a pretty confusing intersection. In a proper city I think they make no sense at all.

Disagree. Left turns on green are a compromise that prevents people from going through the green 50yd past the intersection and banging a u-turn, which is exactly what they'll start doing if you don't let them turn left at the intersection but do let them legally turn left into businesses and whatnot across the street.

Divided roads mostly don't need left on green since they mostly have dedicated turn lanes.

Not everyone would call Los Angeles a proper city, but it's dense and there are very few protected left turns. As thrilling as passing against oncoming traffic on a two lane road.

Stop lights will never be smart enough to tell you when you can "just go" until they're good enough to drive the cars for you, and then that choice will be taken from you anyhow.

Drivers must always pay attention to what's going on around them. Trying to simplify their decisions will just end up with more people getting hurt as drivers claim they had the right because the light said so.

Other countries have a green arrow and here we also have a system where the green arrow goes blank when pedestrians are allowed to cross aka ‘give way’.

Not that it stops pedestrians crossing whenever they like or people running reds, but it does take some of the stress out of driving.

Here's a link to some traffic light systems that you can trust most of the time. But nothing is perfect, so you're still required to pay attention yourself too, of course.

https://www.youtube.com/watch?v=knbVWXzL4-4

simplifying decisions can also lead to extremely inefficient traffic patterns.

Adding a blinking yellow left arrow could help.

That's a little confusing, though, isn't it? A blinking regular yellow light means "you have the right of way, but proceed with caution". But this blinking left arrow would mean "you don't have the right of way, so proceed with caution". The distinction may sound subtle, but is quite large.

"blinking yellow left arrow" is the same thing as not having a protected turn at all.

But it cues your brain that it might not be safe to turn left.

Not quite. Yellow blinking left arrows are always for a protected left turn lane. So when blinking, it does become more like an unprotected 'turn left on green' type of light, but you don't have the straight-through traffic coming up behind you, since you're on a dedicated turn lane. And the yellow flashing arrow is usually timed so that it happens at the safest time to make an unprotected left.

this is a change that's already rolling out nation-wide

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