# Traffic Conundrum **URL:** \ **Category:** In My Humble Opinion\ **Created:** [January 30, 2010, 6:06pm UTC](https://boards.straightdope.com/t/traffic-conundrum/527037 "2010-01-30T18:06:52Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![amarinth](https://avatars.discourse-cdn.com/v4/letter/a/3be4f8/32.png) [@amarinth](https://boards.straightdope.com/u/amarinth)\ **Post date:** [January 31, 2010, 6:47am UTC](https://boards.straightdope.com/t/traffic-conundrum/527037/21 "2010-01-31T06:47:35Z")
> [@Cat\_Whisperer](#): > > I’ve spent my 43 years in various areas of western Canada, and I’ve never seen a flashing green except for an advance green arrow. Canada is a big, varied place. 🙂 True it is a big place. They’re really common in Vancouver and the surrounding area and I’m pretty sure I remember them around the Okanagan and Vancouver Island. So it could just be various parts of BC. ---
**Author:** ![Foldup\_Rabbit](https://avatars.discourse-cdn.com/v4/letter/f/df788c/32.png) [@Foldup\_Rabbit](https://boards.straightdope.com/u/Foldup_Rabbit)\ **Post date:** [January 31, 2010, 8:15am UTC](https://boards.straightdope.com/t/traffic-conundrum/527037/22 "2010-01-31T08:15:44Z")
From BC, where a flashing green indicates a pedestrian-controlled intersection. So it’s a light that will stay green until a pedestrian pushes a button in order to cross. Since I grew up here, I’m finding it kind of fascinating that flashing greens don’t exist in other places. ---
**Author:** ![Noone\_Special](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/noone_special/32/2863_2.png) [@Noone\_Special](https://boards.straightdope.com/u/Noone_Special)\ **Post date:** [January 31, 2010, 8:25am UTC](https://boards.straightdope.com/t/traffic-conundrum/527037/23 "2010-01-31T08:25:05Z")
Without looking at other answers: In Israel, many or even most traffic light have the green light flash 3 times before turning yellow. This is in order to give advanced warning. So, if I’m near the intersection, I’ll go through; if I’m far enough that I won’t reach the intersection before the light turns yellow (which is fairly easy to gauge, as the flashing rate is fixed across all lights,) I’ll start slowing down. So – “Other.” Specifically, “it depends.” ---
**Author:** ![Alessan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/alessan/32/465_2.png) [@Alessan](https://boards.straightdope.com/u/Alessan)\ **Post date:** [January 31, 2010, 10:00am UTC](https://boards.straightdope.com/t/traffic-conundrum/527037/24 "2010-01-31T10:00:28Z")
Speed up. (See preceding post). ---
**Author:** ![mnemosyne](https://avatars.discourse-cdn.com/v4/letter/m/c4cdca/32.png) [@mnemosyne](https://boards.straightdope.com/u/mnemosyne)\ **Post date:** [January 31, 2010, 6:09pm UTC](https://boards.straightdope.com/t/traffic-conundrum/527037/25 "2010-01-31T18:09:48Z")
In Québec, and I’m pretty sure Ontario, a flashing green light is just a priority left turn. So traffic going straight through can treat it as a regular green light, and traffic turning left at that intersection can proceed with the knowledge that the through traffic in the opposite direction has a red light, and so there is no risk of an accident (barring people running red lights, etc). Typically, crosswalks on such intersections have a STOP for pedestrians during this phase of the light cycle, but there is always a chance of a pedestrian crossing the street, especially here in Montreal! So since this is a normal occurrence here - and one desperately hoped for whenever I plan to turn left in this city - I would just continue on my way as I would through a normal green light. ---
**Author:** ![HongKongFooey](https://avatars.discourse-cdn.com/v4/letter/h/c4cdca/32.png) [@HongKongFooey](https://boards.straightdope.com/u/HongKongFooey)\ **Post date:** [January 31, 2010, 6:14pm UTC](https://boards.straightdope.com/t/traffic-conundrum/527037/26 "2010-01-31T18:14:26Z")
Flashing green here means you have the right to go but the opposite direction hasn’t changed green yet. You just go through like you normally would. ---
**Author:** ![Tapioca\_Dextrin](https://avatars.discourse-cdn.com/v4/letter/t/3d9bf3/32.png) [@Tapioca\_Dextrin](https://boards.straightdope.com/u/Tapioca_Dextrin)\ **Post date:** [January 31, 2010, 6:14pm UTC](https://boards.straightdope.com/t/traffic-conundrum/527037/27 "2010-01-31T18:14:31Z")
> [@Noone\_Special](#): > > In Israel, many or even most traffic light have the green light flash 3 times before turning yellow. Same in Mexico. ---
**Author:** ![running\_coach](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/running_coach/32/15836_2.png) [@running\_coach](https://boards.straightdope.com/u/running_coach)\ **Post date:** [January 31, 2010, 6:14pm UTC](https://boards.straightdope.com/t/traffic-conundrum/527037/28 "2010-01-31T18:14:47Z")
> [@mnemosyne](#): > > In Québec, and I’m pretty sure Ontario, a flashing green light is just a priority left turn. So traffic going straight through can treat it as a regular green light, and traffic turning left at that intersection can proceed with the knowledge that the through traffic in the opposite direction has a red light, and so there is no risk of an accident (barring people running red lights, etc). Here in the States, it’s a green arrow pointing left. ---
**Author:** ![Lobsang](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lobsang/32/4067_2.png) [@Lobsang](https://boards.straightdope.com/u/Lobsang)\ **Post date:** [January 31, 2010, 6:28pm UTC](https://boards.straightdope.com/t/traffic-conundrum/527037/29 "2010-01-31T18:28:25Z")
I don’t think I’ve ever seen a green flashing traffic light. Where I live the flashing amber means you can go if it is clear to do so, and they only have them at filters (where you’re turning right but oncoming traffic has right of way) ---
**Author:** ![HongKongFooey](https://avatars.discourse-cdn.com/v4/letter/h/c4cdca/32.png) [@HongKongFooey](https://boards.straightdope.com/u/HongKongFooey)\ **Post date:** [January 31, 2010, 6:32pm UTC](https://boards.straightdope.com/t/traffic-conundrum/527037/30 "2010-01-31T18:32:45Z")
I’m surprised they’re so uncommon elsewhere. Flashing green is used all the time here and they’re very useful for getting traffic through an intersection quickly at certain parts of the day when the flow is heavier to or from a specific direction. ---
**Author:** ![Spoons](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/spoons/32/3141_2.png) [@Spoons](https://boards.straightdope.com/u/Spoons)\ **Post date:** [January 31, 2010, 8:15pm UTC](https://boards.straightdope.com/t/traffic-conundrum/527037/31 "2010-01-31T20:15:57Z")
> [@Cat\_Whisperer](#): > > A flashing green arrow means a dedicated turn arrow here - is this what you mean by flashing green light? In Ontario, to cite one example, a flashing green light functions the same way as a flashing green arrow does in Alberta–it means that you are the only “group” of traffic allowed to go. Cars going through the intersection can proceed through, cars turning left can make their turn, and so on. Some Ontario intersections do have steady (i.e. not flashing) arrows indicating turns, but I’ve never seen a flashing green arrow in Ontario–only flashing green lights. Coming from that background, I admit that I found the OP’s question curious. What do you do at a flashing green light? You go, of course! But the other responses tell me that that might not be a universal reaction. ---
**Author:** ![Cat\_Whisperer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cat_whisperer/32/4839_2.png) [@Cat\_Whisperer](https://boards.straightdope.com/u/Cat_Whisperer)\ **Post date:** [January 31, 2010, 8:28pm UTC](https://boards.straightdope.com/t/traffic-conundrum/527037/32 "2010-01-31T20:28:21Z")
> [@HongKongFooey](#): > > I’m surprised they’re so uncommon elsewhere. Flashing green is used all the time here and they’re very useful for getting traffic through an intersection quickly at certain parts of the day when the flow is heavier to or from a specific direction. I’m not surprised - if the traffic-decision-making people in Calgary knew that flashing green lights would make traffic flow better, they’d not use them on purpose. ---
**Author:** ![mnemosyne](https://avatars.discourse-cdn.com/v4/letter/m/c4cdca/32.png) [@mnemosyne](https://boards.straightdope.com/u/mnemosyne)\ **Post date:** [January 31, 2010, 8:56pm UTC](https://boards.straightdope.com/t/traffic-conundrum/527037/33 "2010-01-31T20:56:17Z")
> [@runner pat](#): > > Here in the States, it’s a green arrow pointing left. We get arrows as well, but usually only when the turn is permitted, but not straight-through traffic. This allows both opposing directions to have priority lefts at the same time, since they don’t interfere with one another while turning. There will also be “forward” and “right” arrows when priority goes to vehicles over pedestrians, or in sequence while pedestrians can cross parallel to through traffic, and then the right arrow appears to allow cars to turn (and pedestrians shouldn’t be in the crosswalk any more). Once in a while, though, they screw it up. The intersection near my house has a priority-straight arrow, then a right-turn allowed arrow is added, and then they both are replaced with a solid circle, _but at no time is a left turn permitted_. ---
**Author:** ![Sunspace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sunspace/32/1250_2.png) [@Sunspace](https://boards.straightdope.com/u/Sunspace)\ **Post date:** [January 31, 2010, 9:28pm UTC](https://boards.straightdope.com/t/traffic-conundrum/527037/34 "2010-01-31T21:28:10Z")
To me a flashing green means I can turn across traffic and go “HA-ha” at the poor oppositely-headed suckers waiting for their direction to turn green. Why yes, I am in Ontario. If there is ONLY a flashing green, it means that you can go straight or make other turns as well. I view this as a cheap way to add a priority turn phase to a three-lamp fixture without adding more lamps. It’s usually called ‘advanced green’ here. I have the impression that flashing green signals are gradually being phased out in favour of sepaprate green/yellow arrows on separate lamps. But the full installation of these, where arterial roads cross, often involves doubling the number of lamp installation locations to give a completely-separate set of signals for turning across traffic. So maybe in smaller areas, such as the left turn off Bloor into the Old Mill subway station bus loop, the flashing green will remain. ---
**Author:** ![Rysto](https://avatars.discourse-cdn.com/v4/letter/r/ecccb3/32.png) [@Rysto](https://boards.straightdope.com/u/Rysto)\ **Post date:** [February 1, 2010, 1:09am UTC](https://boards.straightdope.com/t/traffic-conundrum/527037/35 "2010-02-01T01:09:46Z")
> [@Sunspace](#): > > I have the impression that flashing green signals are gradually being phased out in favour of sepaprate green/yellow arrows on separate lamps. But the full installation of these, where arterial roads cross, often involves doubling the number of lamp installation locations to give a completely-separate set of signals for turning across traffic. So maybe in smaller areas, such as the left turn off Bloor into the Old Mill subway station bus loop, the flashing green will remain. You don’t always need a full set of signals. Plenty of intersections just have the green arrow bolted below the regular green. The full set of signals is only necessary when traffic engineers, in their infinite wisdom, decide that they need to disallow left turns on a normal green light. ---
**Author:** ![elfkin477](https://avatars.discourse-cdn.com/v4/letter/e/a9a28c/32.png) [@elfkin477](https://boards.straightdope.com/u/elfkin477)\ **Post date:** [February 1, 2010, 7:28am UTC](https://boards.straightdope.com/t/traffic-conundrum/527037/36 "2010-02-01T07:28:54Z")
> [@Spoons](#): > > it means that you are the only “group” of traffic allowed to go. Cars going through the intersection can proceed through, cars turning left can make their turn, and so on. I’m sure this is going to sound stupid to someone who actually deals with flashing green lights, but to what advantage it is to you to know if you’re the only one who can go or not? There are a few intersections in Dover, NH that were designed by a crazy person (they allow people facing each other to turn into the same lane at the same time - having been on both sides of the intersection, I know neither direction is told by lights or signage to yield, either) but generally speaking in the US the other cars can only legally proceed at the same time as you when it’s safe to do so, so I’m failing to see how being told that I’m the only one who can go helps at all. ---
**Author:** ![Wheeljack](https://avatars.discourse-cdn.com/v4/letter/w/838e76/32.png) [@Wheeljack](https://boards.straightdope.com/u/Wheeljack)\ **Post date:** [February 1, 2010, 8:58am UTC](https://boards.straightdope.com/t/traffic-conundrum/527037/37 "2010-02-01T08:58:40Z")
> [@troub](#): > > I did see a light once that had a solid green light illuminated, but was _also_ flashing red. In all directions. The reality in that situation is simply that it is a harrowing experience, and you just do what you can to avoid an accident. Some people saw the green and just blew through, some saw the flashing red and treated it as a four-way stop, others slowly went through like a yellow. Definitely one of the scariest situations I’ve ever dealt with in a car (and I’ve been in several other near-misses and witness to shenanigans, but nothing quite like this). Ooo, I want to play. A few years ago, at the intersection of a six lane+turns highway and a two lanes+turns crossroad, I saw all the lights switch to flashing red at once. Everybody stopped, and then everybody went. It was an absolute mess. I was waiting at the back of the line in a thru-lane on the crossroad, and after watching for a little while I just backed up and crossed the highway elsewhere. As the intersection moved out of sight in my rear-view mirror I saw that the cross traffic had changed to solid red, but I decided not to take my chances. A flashing green, though? I’d slow down to see what was going on, and proceed with caution. ---
**Author:** ![Noone\_Special](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/noone_special/32/2863_2.png) [@Noone\_Special](https://boards.straightdope.com/u/Noone_Special)\ **Post date:** [February 1, 2010, 9:09am UTC](https://boards.straightdope.com/t/traffic-conundrum/527037/38 "2010-02-01T09:09:01Z")
Just to expand on my previous response (Flashing green means “about to turn yellow”) – Israeli traffic lights **do not** allow turning left across traffic. If a left turn is allowed, either you have a separate left turn arrow (and when it is green you are assured that the other direction has a red light) or if it’s just a plain old green circle, then the two directions are not getting green lights at once at all – and you’re still assured of not having to cross throuigh traffic. Essentially, a green light is **always** a “priority green,” regardless of whether you’re going straight or turning. There is also no right turn on red (although special right-turn lanes, governed by a flashing yellow light and generally physically separated from the striaght ahead lanes, are pretty much ubiquitous on main roads. In this case, you will be turning into / merging with through traffic [or with traffic completing a left turn on green, which under these conditions should still be considered as through traffic!] and the through traffic **will** have right of way.) So, there is no reason for a flashing green light to mean anything **other** than “be prepared for the light to turn yellow.” ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [February 1, 2010, 11:58am UTC](https://boards.straightdope.com/t/traffic-conundrum/527037/39 "2010-02-01T11:58:14Z")
I answered ‘slow down’ - my actual answer would be ‘slow down and proceed with extreme caution’ I’ve never seen a flashing green traffic light, but I can’t think of any kind of hazardous or othwerwise unfamiliar road traffic situation that is: [ul] [li]Observable as happening in the direction of travel[/li][li]Improved by speeding up[/li][/ul] ---
**Author:** ![racer72](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/racer72/32/3075_2.png) [@racer72](https://boards.straightdope.com/u/racer72)\ **Post date:** [February 1, 2010, 1:55pm UTC](https://boards.straightdope.com/t/traffic-conundrum/527037/40 "2010-02-01T13:55:47Z")
I saw flashing green lights while in Oregon last year, I had never seen them before. Apparently at intersections that have had problems with folks running red lights it is an additional notice that the light is about to change. I sat through a light cycle and watched the light go from solid green, flashing green, yellow, red then solid green. The clerk at the hotel where I was staying told me she gets asked about the flashing green lights quite often. [Previous page](https://boards.straightdope.com/t/traffic-conundrum/527037.md?page=1) [Next page](https://boards.straightdope.com/t/traffic-conundrum/527037.md?page=3)