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NPR had a story about how self-driving cars in Pittsburgh wouldn't be adhering to the "Pittsburgh-left": "Even harder for autonomous cars to master are local q
by uptown 9y ago
NPR had a story about how self-driving cars in Pittsburgh wouldn't be adhering to the "Pittsburgh-left":
"Even harder for autonomous cars to master are local quirks; things like "the Pittsburgh left." That's a custom unique to the city that allows the first driver trying to make a left turn to do so before oncoming cars pass through an intersection. It's one thing that Emily Duff Bartel says Uber's fleet of self-driving cars won't be programmed to practice. "We're following the rules on this one," she says."
https://www.npr.org/sections/alltechconsidered/2017/04/03/522099560/pittsburgh-offers-driving-lessons-for-ubers-autonomous-cars https://www.npr.org/sections/alltechconsidered/2017/04/03/52...
- forgotmypw 9y agoThis custom is prevalent in places other than Pittsburgh. It can also get you a citation if a cop sees it.
- bsder 9y agoIt depends. Most cities whose road network predates cars have "local customs" which are essential to keep traffic flowing. These "local customs" may not be strictly legal, but you rarely will wind up with a ticket for it.
- megablast 9y agoAs it should, what a ridiculous thing to do.
- chcknsammich 9y agoSays the person who has never seen the ridiculous thing that is single lane road deadlock.
- lttlrck 9y agoIndeed. When I first came to the US I lived in Boston and this happens quite frequently inside the I95. It used to drive me crazy, I hated it, I though it was dangerous and uncivilized :-) it didn’t take long for me to understand why it was necessary and to start doing it myself.
- forgotmypw 9y agoFor a responsible driver, it is a test to see if you are paying attention. A careful driver will see this about to happen, anticipate it, and allow the turning driver to make his impatient left safely.
- dabbledash 9y agoPull into the intersection and go when it’s clear (on yellow or red). Gunning it so you can cut off oncoming traffic is ridiculous.
- Izkata 9y agoThat doesn't solve it at all, you're thinking of a different problem. I got clued in from another comment that only mentioned it offhand, but this is the problem the "Pittsburgh left" tries to solve: The traffic is a single lane, and you want to turn left. Light turns green, and you wait for the oncoming traffic to clear. All traffic behind you is stopped on a green because they can't get around you.
- c22 9y agoEven with multiple lanes this can be an issue as people behind you try to merge right to pass you which in busy traffic increases the chance of accidents and causes slowdowns.
- dabbledash 9y agoThanks, that’s a great point. That really is a terrible situation. And I’m sure the risks associated with the “Pittsburg left” are significantly mitigated when everyone expects it.
- yosito 9y agoIf single lane road deadlock is a problem, the city's urban planners should (and probably will) install a left turn signal to solve it. A better solution than reckless driving is to report the deadlock to the city.
- jhauris 9y agoMany of the roads in the city of Pittsburgh are carved into the mountain, sometimes with shops or houses on either side between the road and cliff face. The terrain there is not a trivial thing to engineer around.
- deleted 9y ago[deleted]
- ericpauley 9y agoYou clearly have never been to Pittsburgh. There is simply no room at some intersections for a left turn lane, and a left turn signal would needlessly block traffic going the other way even when nobody wants to turn left.
- intrasight 9y agoAs a long-time but not native Pittsburgher, I have to agree. The "Pittsburgh Left" is dangerous . There are arguments here that it eases traffic flow by "crowd-sourcing" a left-turn light or that without it there'd be a backup of traffic. What rubbish. A left turn light allows several (dozens at some intersections) make a left. A "Pittsburgh Left" only allows one reckless, impatient driver make this left. And I see it more often on four lane roads than on two lane roads so I discount the eases traffic flow argument. It's a moving violation with a heavy fine and points on your license - as it should be.
- hnrodey 9y agoI'm from near Pittsburgh and I'd hardly call this a custom. It's just what you do when you're in a hurry and have pole-position in the turning lane...
- sparky_z 9y agoNot sure what you mean. "Just what you do" when you're from a specific area is pretty much the textbook definition of a "custom".
- hn_throwaway_99 9y agoI think the parent's argument is that it's not a custom to think of this as really accepted behavior. That is, an agressive driver turning left in a hurry may gun it, and the driver going straight may let him through to avoid an accident, but it's not "custom" to the point that that word implies it's accepted.
- ianamartin 9y agoIt's a dick move. But people do it a lot anyway.
- jve 9y agoWell, in Latvia we ofcourse have a law, but in real life I was tought that I and the driver in front of me should decide how we turn left. Kind of look at what the other driver does and react accordingly or make initiative myself. Edit: oh sorry misunderstood what pittsburg left meant. I was describing situation when both cars turn left. There are 2 options: cube path, that is paths cross, cars pass one by one, or 2 arc paths not intersecting.
- setr 9y agoI've seen this often in southern california and chicago, the only two cities I've driven heavily; and despite having no interaction with Pittsburgh, I do it myself all the time... I can't imagine how this is a Pittsburgh quirk; its the obvious thing to do when the option is available
- kevin_thibedeau 9y agoObvious to not respect the right of way? Or fall prey to insurance fraud if you misinterpret the "benevolent" driver who you thought was letting you jump the turn.
- deleted 9y ago[deleted]
- matte_black 9y agoIs this the same as pulling straight into the middle of the intersection with live traffic swirling around you on both sides then making the left after the lights have reddened and traffic has cleared?
- _greim_ 9y agoIt sounds similar. I stopped doing it years ago after seeing too many close calls. But I live in an area where other people don't exactly accommodate the behavior.
- maxsilver 9y agoIt sounds like the opposite of that -- letting the left turn car go before both sides move, rather than after both sides finish. The behaviour you just described is what everyone does in Michigan. The Pittsburgh left sounds friendlier, but more risk prone to people who don't expect it or respect it.
- thereisnospork 9y agoCorrect, although the creep and go after the light is also practiced. Main reason for the Pittsburgh left's popularity is that there are a number of roads in and around the city where during rush hour it's otherwise impossible to ever make a left and have no turn lane.
- Izkata 9y ago> and have no turn lane. Urgh, that's something missing from the other comments. Now it makes sense to me.
- userbinator 9y agoIn other words, despite the traffic lights not having an official "left turn only" phase, the traffic has naturally created one. I've seen this in China too.
- c22 9y agoThis happens to me sometimes, my solution is to overshoot by a block, then hook 3 right turns, rather than slow up everyone behind me or pull a daredevil left. I would hope self driving cars would be programmed to follow a strategy like mine while still accommodating daredevils by using cautious acceleration and effective collision avoidance.
- blahedo 9y agoNot unique to Pittsburgh (also prevalent in Rhode Island, among other places), but more importantly, letting the first car turn left first is useful to keeping traffic flowing on narrow roads—which, in the areas that use this tactic, rely on it. So, not following local customs is a good way to snarl traffic (since the oncoming traffic will be waiting for the car to take its turn).
- fjsolwmv 9y agoObviously if the law is wrong it should be changed. Then the question becomes, can a car be programmed to follow the more complex law.
- sharonzhou 9y agoI think it's less about complexity and more about precision. A simple law can be extremely difficult to encode if it lacks specification.
- systoll 9y agoNot that I'd recommend doing it in an area not used to it... but that sounds like a riskier alternative to a hook turn. With hook turns, If you want to turn right, you start in the leftmost lane. When your light goes green, you 'hook' around to put yourself in front of the cars to your [initial] left. From there, the road you want to enter is straight ahead. This way, no-one cuts across lanes where traffic has a green light.
- Noumenon72 9y agoThis makes no sense to me even after assuming you are from a country that drives on the left and reading the Wikipedia page.
- melkiaur 9y agoOk, let's use normal right-sided driving method. Imagine you're vulnerable (on a bike, or worse: on an electric scooter), and you want to turn left. You were going northbound and want to go westbound. In "normal" fashion, you'd have to stay on the left of your lane, and wait for the traffic coming in front of you to die down before you can cross. That puts you straight in the middle of the intersection for some time, which is dangerous. With a hook turn, you go and wait along with the traffic coming from the east to the west. They are stopped, so they are not a danger to you. When the east-west traffic light finally turns green, you won't be crossing anyone's traffic, and you'll be already standing on the rightmost part of your new road.
- seattle_spring 9y agoPretty sure that's just an asshole thing, not a "local quirk." It's like saying not using your turn signal is a funny quirk of BMW drivers, or going 55 in a 70 in the left lane in a Prius.
- ubernostrum 9y agoThis type of left turn is less an "asshole thing" and more a "drivers compensating for poor design" thing. Typically, the "Pittsburgh left" is used in places where there should be a protected left turn as part of the signal cycle, but there isn't, and at times of high traffic flow it's the only way for any traffic to complete the turn (since waiting for oncoming traffic to clear on a green essentially means waiting until the multi-hour-long period of high traffic is over).
- Ajedi32 9y agoWon't the oncoming traffic clear once the light turns red? That's usually enough for the 2-3 cars waiting in the intersection to complete their turn.
- ubernostrum 9y agoThe usual case for this is a light where left-turning traffic must wait for oncoming traffic to clear, but at certain times of day oncoming traffic never clears. The only gap in oncoming traffic occurs when the oncoming traffic has a red light. But the left-turning traffic also has a red at that point.
- Ajedi32 9y agoI thought we were talking about the Pittsburgh-left. That's not what you're describing. The Pittsburgh-left occurs immediately after the light turns green, when both the oncoming traffic and the person making the turn have a green light. My point was, why do you need to do that when you can just enter the intersection during the green light and complete your turn once the light turns red?
- Shivetya 9y agoSo I am curious if companies have popped up who will try to provide localization for traffic laws similar to how we have companies that provide data on zip codes to regulated materials. an example would be to know when a right turn on red is permitted even without signage. which while not a quirk there are many small towns with special rules that tend to catch people off guard.
- sulam 9y agoPittsburgh needs to do what we do in (some intersections in) California — ban left turns during rush hour on intersections with no left turn lane. Everyone still gets where they need to go and traffic moves much more smoothly.