Flashing traffic lights--yellow/yellow?

[Geobabe]

In a discussion on another board about how to proceed at an intersection where the traffic light is flashing yellow, a couple of people claimed to have seen lights flashing yellow in all directions. I have only ever seen yellow/red (i.e. traffic for one direction-- e-w or n-s --has yellow and cross traffic has red) or all red, and it's always been my assumption that that is built in to their design, since the usual driver's ed instruction is to proceed with caution on a flashing yellow and stop on flashing red. Google isn't helping me much here, so I'm hoping we have somebody here who actually knows something about this. I don't know enough about how traffic signals work to really argue this point, so is it possible for a malfunctioning light to flash yellow/yellow rather than yellow/red or red/red? I'm sure there could be some massive malfunction that could cause pretty much anything to happen, but I mean in the most likely malfunction conditions, is it possible?

[Harmonious Discord]

There is no reason lights in all directions couldn't flash yellow all at the same time. I can't see a city setting them up to do that, because as you noted only one road should have flashing yellow. Different light models will have their specific abilities. There is no standard controller that all lights must use. The mayor in Portage had complained this summer that three of the lights couldn't be set up a certain way because of their hardware. They are being replaced with ones that can do what is wanted.

[Polycarp]

Originally Posted by Harmonious Discord

There is no reason lights in all directions couldn't flash yellow all at the same time. I can't see a city setting them up to do that, because as you noted only one road should have flashing yellow. Different light models will have their specific abilities. There is no standard controller that all lights must use. The mayor in Portage had complained this summer that three of the lights couldn't be set up a certain way because of their hardware. They are being replaced with ones that can do what is wanted.

I can think of an outstanding reason why one should not have four-way-flashing-yellow, given most states' traffic laws: Flashing yellow normally indicates that you have the right of way but are entering a situation of above-normal danger, so proceed cautiously. Hence, flashing yellow all four ways would tell motorists entering an intersection from all directions that they had the right of way over crossing traffic but that caution was indicated.

[Q.E.D.]

He means a physical reason, Poly.

[butler1850]

Originally Posted by Q.E.D.

He means a physical reason, Poly.

I'd say that in many cases, there would be a physical reason built into the controlling software. It wouldn't be a good idea, so they program the controller to not allow it. (Idiot proofing, though a good idiot can always find a way around things.) With the right controlling hardware/software, there would be no physical reason that it can't be done, but with the default, it's likely impossible.

If a site needs a permanent 4x flashing yellow, it would generally have only that yellow light, and have stop signs on at least 2 of the streets entering the intersection. In my neck of the woods, there are many intersections with a 4-way light to let you know that there is reason for caution, but not enough need for a full signal.

[DSYoungEsq]

Originally Posted by Polycarp

I can think of an outstanding reason why one should not have four-way-flashing-yellow, given most states' traffic laws: Flashing yellow normally indicates that you have the right of way but are entering a situation of above-normal danger, so proceed cautiously. Hence, flashing yellow all four ways would tell motorists entering an intersection from all directions that they had the right of way over crossing traffic but that caution was indicated.

Well, true, BUT:

If you are approaching an intersection with a flashing yellow, you are not supposed to simply drive through it as if it was a green light, despite the fact this is what most people do. It means you slow down, look as you approach, and make certain that the way through is uncontested. If someone from the side is approaching and not stopping, prudence dictates not entering the intersection.

I've seen residential intersections where there is no stop sign in either direction, only yield signs. The effect is the same.

From a practical standpoint, I seriously doubt that any city would purposefully set up an intersection with flashing yellows in both directions. The potential liability would be significant.

[SCSimmons]

Originally Posted by DSYoungEsq

I've seen residential intersections where there is no stop sign in either direction, only yield signs. The effect is the same.

But again--have you seen such an intersection with yield signs for both streets? IME, one crossing street has a yield sign and the other has nothing, because the second street has right-of-way. Yield signs on all corners would indicate to each driver that the other driver has right-of-way, which doesn't make sense ...

[engineer_comp_geek]

I've seen four way flashing yellows many times. They used to have quite a few of them in the town where I grew up. They would function as normal traffic lights during the day, then would switch over to flashing yellow at night. Keep in mind this is a small town where at 1 am you are lucky to have 1 or 2 cars out in the entire town, and the chances of you even seeing another car at an intersection late at night are pretty small.

The other case where I've seen it is when mutliple lights are all controlled from a single location, such as synchronized lights in large cities. If the main controller goes down (like there's a power outage or some speeding moron takes down a utility pole), the individual intersections still have controllers, but since they can't talk to the main controller, they go into a flashing yellow pattern. These are usually programmable, so they might do yellow in all four directions, or, more likely, they'll do yellow in two directions and red in the other two, with the yellows used on the directions that gets more traffic. They may even go into an unsynchronized mode where they still do the green-yellow-red thing. It all depends on how the traffic engineer decided they should be programmed.

[DSYoungEsq]

Originally Posted by SCSimmons

But again--have you seen such an intersection with yield signs for both streets? IME, one crossing street has a yield sign and the other has nothing, because the second street has right-of-way. Yield signs on all corners would indicate to each driver that the other driver has right-of-way, which doesn't make sense ...

Yes, I have seen such an intersection. I said so in my last post.

[Q.E.D.]

Originally Posted by DSYoungEsq

I said so in my last post.

No, you didn't. Not in a way which was clearly understood.

[DSYoungEsq]

Originally Posted by Q.E.D.

No, you didn't. Not in a way which was clearly understood.

Ah, I see what you mean.

Makes me think of Horton: "I meant what I said, and I said what I meant."





Riiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiight...

[Geobabe]

Originally Posted by engineer_comp_geek

I've seen four way flashing yellows many times. They used to have quite a few of them in the town where I grew up. They would function as normal traffic lights during the day, then would switch over to flashing yellow at night. Keep in mind this is a small town where at 1 am you are lucky to have 1 or 2 cars out in the entire town, and the chances of you even seeing another car at an intersection late at night are pretty small.

Interesting; I've always lived in fairly busy suburban/urban locales and had never encountered a yellow/yellow that I could recall. The discussion this question sprang from takes place in the Atlanta area, so I would not expect to see many of those around here--a flashing light at all is usually a malfunctioning one.

A lot of drivers around here tend to try to be a little too courteous or cautious, and everybody friggin' stops at the flashing yellow and traffic backs up forever. Some of the posters in the thread are asserting, "But the light might also be yellow in the other direction! You have to treat it as a four-way stop!" so I figured I'd spoil their gabfest with a few facts if I could (including pointing out the the official GA state driver's manual says to proceed with caution on a flashing yellow, not stop).

[A.R. Cane]

The only place I can imagine 4 way yellow, or yield signs all round, is on a roundabout/traffic circle. I've seen, in older residential neighborhoods, where there were no traffic contols, at all, of some interesections. The speed limits are usually very low, visibility is unobstructed and the "thoroughfair", is often obvious, meaning that side streets must stop even though there are no signs, or signals.

[Shagnasty]

Like engineer_comp_geek I have seen it many times as well. All three of the red lights in my home town switched over to flashing yellows in all directions at 9 pm every night. That is pretty common in very small towns at least in the South. Of course, the reason that was a workable plan was that there just weren't many cars out then.

[NinetyWt]

New signals also flash yellow/yellow for a period of time before they are put on-line. This is to alert drivers in the area that "hey, there's a new signal going up here! Be prepared to stop when we turn them on next week!". Perhaps this was seen in a part of Atlanta which is seeing some growth, thus new signal?

[A.R. Cane]

I'm not from Missouri, but since this is GQ you're going to have to show me anyway. No local govt. entity is going to permit such a negligent situation to exist. I don't care how small and isolated a community is, sooner or later there's going to be an accident caused by such a circumstance and the local taxpayers are going to be holding the bag for any findings of liability. I've got more miles behind a steering wheel than most Dopers and I've driven through thousands of burgs, I've seen some pretty screwy traffic patterns, but I've never seen an straight intersection w/ a 4 way yellow flasher.
I think you folks are either color blind, gettin' a bit forgetful, or just talkin' through your hats.

[Chronos]

How is a traffic signal flashing yellow in all directions any more negligent than an intersection with no traffic signal at all? You might be surprised to hear that those still exist in some places, too, despite not requiring anyone to stop.

[A.R. Cane]

Originally Posted by Chronos

How is a traffic signal flashing yellow in all directions any more negligent than an intersection with no traffic signal at all? You might be surprised to hear that those still exist in some places, too, despite not requiring anyone to stop.

As I stated in an earlier post, I've seen intersections w/ no control, but that leaves it up to the driver to exercise caution and yield right of way. Placing a misleading traffic control device is a positive act that directly misleads drivers into believing that the have the right of way.

[DSYoungEsq]

Originally Posted by A.R. Cane

As I stated in an earlier post, I've seen intersections w/ no control, but that leaves it up to the driver to exercise caution and yield right of way. Placing a misleading traffic control device is a positive act that directly misleads drivers into believing that the have the right of way.

As I stated previously, a flashing yellow does NOT tell you you have the unimpeded right of way. It tells you to approach the intersection with caution, and not to enter it unless certain you are able to drive through without problems.

I know people don't treat them that way, but that's what they mean.

[Bagistan]

If anyone cares, flashing yellow in all directions is normal error/fallback/disabled traffic light behaviour in Europe (at least in my parts). The message is (freely put) "Proceed as if there were no lights at all, but with caution, as something is definitely up".

Not that this has much to do with the discussion here (as the OP is about U.S. lights), but beware of this when googleing or collecting anecdotes.

[A.R. Cane]

Originally Posted by DSYoungEsq

As I stated previously, a flashing yellow does NOT tell you you have the unimpeded right of way. It tells you to approach the intersection with caution, and not to enter it unless certain you are able to drive through without problems.

I know people don't treat them that way, but that's what they mean.

The flashing yellow indicates a need for caution, but it also implies right of way. You're the lawyerman, you should know I'm not going to be cowed by your throwing that "unimpeded" in there. Show me a definitive cite and I'll back down. No cite? Then your trying to reinforce your weak point w/ obfuscation.
My practical experience trumps your legal expertise for now.

[Geobabe]

Originally Posted by NinetyWt

New signals also flash yellow/yellow for a period of time before they are put on-line. This is to alert drivers in the area that "hey, there's a new signal going up here! Be prepared to stop when we turn them on next week!". Perhaps this was seen in a part of Atlanta which is seeing some growth, thus new signal?

True, I have seen new signals flashing yellow. I think what people are mostly talking about in the other board's thread, though, is lights that have been knocked out of sync by a storm and go into flash mode, as noted above. This article was cited as evidence that you should treat some flashing yellows as a four-way stop, but I think that's just a misreading of a poorly-written article.

[DSYoungEsq]

Originally Posted by A.R. Cane

The flashing yellow indicates a need for caution, but it also implies right of way. You're the lawyerman, you should know I'm not going to be cowed by your throwing that "unimpeded" in there. Show me a definitive cite and I'll back down. No cite? Then your trying to reinforce your weak point w/ obfuscation.
My practical experience trumps your legal expertise for now.

From the California Driver Handbook, 2007[pdf]:

Flashing Yellow. A
flashing yellow signal
light warns you to be
careful. You do not
need to stop for a flashing yellow
light but you must slow down and
be especially alert before entering
the intersection.

Which, you will note, is exactly what I said.

[A.R. Cane]

I think we have different interpretations on then definition of "exactly". So answer me this: You're driving on a highway and approaching an intersection w/ a flashing yellow light. Do you not expect that cross traffic has a flashing red?
I certainly do and I expect that any experienced driver would also.

[OldGuy]

Originally Posted by DSYoungEsq

I've seen residential intersections where there is no stop sign in either direction, only yield signs. The effect is the same.

no completely different. Yield signs in both directions tell each driver the other has the right of way. Flashing yellow in both directions tells each driver s/he has the right of way.

[Genaro]

Originally Posted by Geobabe

In a discussion on another board about how to proceed at an intersection where the traffic light is flashing yellow, a couple of people claimed to have seen lights flashing yellow in all directions. I have only ever seen yellow/red (i.e. traffic for one direction-- e-w or n-s --has yellow and cross traffic has red) or all red, and it's always been my assumption that that is built in to their design, since the usual driver's ed instruction is to proceed with caution on a flashing yellow and stop on flashing red. Google isn't helping me much here, so I'm hoping we have somebody here who actually knows something about this. I don't know enough about how traffic signals work to really argue this point, so is it possible for a malfunctioning light to flash yellow/yellow rather than yellow/red or red/red? I'm sure there could be some massive malfunction that could cause pretty much anything to happen, but I mean in the most likely malfunction conditions, is it possible?

In California, some cities are now flashing green. The local newpaper has a trafic Q&A, which stated it was get people's attention (stop and wondering what it meant)and serve the same purpose as flashing red.

[A.R. Cane]

Originally Posted by Genaro

In California, some cities are now flashing green. The local newpaper has a trafic Q&A, which stated it was get people's attention (stop and wondering what it meant)and serve the same purpose as flashing red.

C'mon folks, this is GQ, not "Can You Top This". Cite, cite, cite!!

[DSYoungEsq]

Originally Posted by A.R. Cane

I think we have different interpretations on then definition of "exactly". So answer me this: You're driving on a highway and approaching an intersection w/ a flashing yellow light. Do you not expect that cross traffic has a flashing red?
I certainly do and I expect that any experienced driver would also.

NO!!! And that's the whole point!!!!!! YOU may think that, but it's not the law, it's not the truth, and you've been shown that:

California doesn't tell you to accept that;

Real locations actually do this (flash yellow both ways).

If you wish to hold to your misguided notion of what flashing yellow lights means, by all means, go ahead. I hope you don't have to drive through any of the intersections we've had under discussion!!

Old guy: If you read what I posted before, flashing yellow does NOT tell you you have the right of way. It tells you that you do not need to stop, but, as with all intersections at which there is no stop sign in the other direction, you must "respect" (the term California uses) the right of way of other drivers with a better right to proceed (usually, they got there first).

[A.R. Cane]

Originally Posted by DSYoungEsq

NO!!! And that's the whole point!!!!!! YOU may think that, but it's not the law, it's not the truth, and you've been shown that:

California doesn't tell you to accept that;

Real locations actually do this (flash yellow both ways).

If you wish to hold to your misguided notion of what flashing yellow lights means, by all means, go ahead. I hope you don't have to drive through any of the intersections we've had under discussion!!

Old guy: If you read what I posted before, flashing yellow does NOT tell you you have the right of way. It tells you that you do not need to stop, but, as with all intersections at which there is no stop sign in the other direction, you must "respect" (the term California uses) the right of way of other drivers with a better right to proceed (usually, they got there first).

I can only say that you couldn't be more wrong and you have yet to provide any proof of an intersection w/ 4 way yellow flashers. That's because it's tota;;y illogical, goes against the standard meaning of traffic signals and does not exist in the U.S., unless by some exremely unusual accident, which I still doubt.
Frankly I'm amazed that a person trained in the law would accept the premiss to begin with.

[TheLoadedDog]

More international traffic weirdness...

Australian traffic lights ONLY have flashing yellow for ALL directions. You can see it on a keyhole at the electronics box on one of the poles: "NORMAL - FLASHING YELLOW - OFF"

Local traffic law is that when approaching a flashing yellow light, you stop at the stop line and, in the absence of a police officer on point duty, you give way as per an uncontrolled intersection.

Flashing yellow here is rare and it screams out at you "SOMETHING WEIRD IS GOING ON" so you go through that intersection on bloody eggshells. I can't imagine anything worse than having some drivers facing a "hey, it's a nice day, everything's fine" common or garden variety green light. Flashing yellow is a big deal. It's reassuring to know everybody is seeing the same thing.

[TheLoadedDog]

Sorry. To answer the OP: Australian traffic lights are programmed to flash yellow four ways. I don't have a cite handy, but I've no reason to lie about it either. So such lights DO exist.

[NinetyWt]

Geobabe allow me to add that I've only seen it a few times. The rest of the times the new signal flashes red on the secondary street ways and yellow on the main street ways. It seems to be dependent upon the individual intersection (traffic counts, alignment, etc. ).

[DSYoungEsq]

1. engineer_comp_geek says, "I've seen four way flashing yellows many times. They used to have quite a few of them in the town where I grew up." He lives in Pennsylvania, and I have no reason to believe he grew up outside the US. Oh, but of course he must be wrong, because A. R. Cane says so.

2. The law provides no indication that it can't happen, nor is it totally illogical. I concede it would be rare, for many of the reasons you've indicated (which, as you might recall, I said in my first post). But that doesn't make it impossible. Oh, wait, except that A. R. Cane says it can't be so.

Unlike you, who argue from a total lack of knowledge, only your intuition, there does appear to be evidence of four-way yellow flashers presented in this thread, from America. I frankly don't care anymore if you want to accept that or not; play the three monkeys if you prefer.

[A.R. Cane]

Originally Posted by DSYoungEsq

1. engineer_comp_geek says, "I've seen four way flashing yellows many times. They used to have quite a few of them in the town where I grew up." He lives in Pennsylvania, and I have no reason to believe he grew up outside the US. Oh, but of course he must be wrong, because A. R. Cane says so.

2. The law provides no indication that it can't happen, nor is it totally illogical. I concede it would be rare, for many of the reasons you've indicated (which, as you might recall, I said in my first post). But that doesn't make it impossible. Oh, wait, except that A. R. Cane says it can't be so.

Unlike you, who argue from a total lack of knowledge, only your intuition, there does appear to be evidence of four-way yellow flashers presented in this thread, from America. I frankly don't care anymore if you want to accept that or not; play the three monkeys if you prefer.

In GQ, no difinitive cites provided and even your ambiguous cite states, "You do not need to stop for a flashing yellow light", what other conclusion could be drawn except that right of way is implied? I too am at an end.

[Genaro]

Originally Posted by A.R. Cane

C'mon folks, this is GQ, not "Can You Top This". Cite, cite, cite!!

Ok, here's your cite. Michelle Groh-Gordy, Drive Time, Inland Valley Daily Bulletin

http://www.dailybulletin.com/search/...lybulletin.com

[A.R. Cane]

Originally Posted by Genaro

Ok, here's your cite. Michelle Groh-Gordy, Drive Time, Inland Valley Daily Bulletin

http://www.dailybulletin.com/search/...lybulletin.com

Here's the bit from your cite:
"Question: A few Monday mornings ago, as I passed Ontario High School and approached an intersection, I realized that the green signal light was flashing. I looked again, thinking I was seeing things (as I think other drivers were doing, since all the traffic came to a halt). In the 20-plus years I have been driving, I have never seen flashing green lights.
I crossed the intersection, then heard and saw an approaching police car with lights and sirens in full force. I looked in my rear-view mirror and saw the green light still flashing, then I watched as the police car moved through the intersection and the lights became solid green.

I am assuming the police car was able to control the intersection signal light. Am I correct?

- Louise Shane, Ontario


Answer: Made you look, didn't it, Louise? Well, that is exactly what the officer in the police car that activated the light wanted you to do.

Many emergency agencies, including the fire and police departments, have the ability to remotely interrupt traffic signals from inside their vehicles. It may be hard to believe, but the authorities have found that many people think that a yellow light means "go faster." The flashing green light is turned on to elicit the exact response you gave - it lets you know that you can go, but heightens your level of awareness and caution for the emergency vehicle that is forthcoming."

I admit it's a new one on me. I'm aware that there are devices used in emergency vehicles to control traffic signals, but I'm not sure of the specifics of how it works. I know we had a collision here recently, between a fire rig and a light rail train. It seems that both can control traffic lights upon their approach and someone hadn't taken this into consideration, whoops!
I'll concede the exception, but it doesn't directly answer the 4 way yellow flasher question.

[ENugent]

In Cars (which my three-year-old requests to watch nightly, so I've probably seen it twenty times), there is a flashing yellow both ways at night in Radiator Springs. I've never seen it in real life, but my experience is that Pixar doesn't screw up details like that.

[NinetyWt]

A. R., that device is the Opticon. I remember it because our city traffic engineer was always frustrated after one of our fire trucks came thru a signal and disrupted the normal programmed regime of the signals. Often he (or a tech) would have to go to the intersection and manually re-set the thing.