Traffic signal

[myosh_tino]

The way I learned it in Drivers' Ed in Mass a couple decades (plus a couple years) back is that flashing green means "subject to change"

Heh, that statement brought back a funny high school memory.  When I took Drivers Ed in California a couple of decades ago, we were discussing traffic lights and one of the comments the teacher made was if we see a flashing green light, that means we were smoking crack.  He goes on to say we should *never* see a flashing green light... EVER! (except in Massachusetts)

[roadman65]

I have seen lights in Fort Lauderdale and in the State of Delaware where flashing red appears at left turn signals meaning that if the way is clear you can go.  Otherwise, if not the signal timer will expire on the opposing side and turn a steady red (as the signal is always green on the other side when flashing red on yours). 

Glens Falls, NY used to use them at one intersection north of NY 254 on US 9 for the side road there.   It was a regular intersection that never had a steady red on the side road, and was always flashing as this really just was a typical stop street. It was just with a traffic light that kicked in if there was too much traffic on US 9 after a motorist waited to cross it indefinetley here.  I did not see it last week when I was there, so it must be one of the many added working signals along US 9 as traffic counts increased over the decades ( we are talking about back in the 70s when I saw this) and a full signal is now needed there.

[kphoger]

I still think that when they were coming up with the meanings of flashing lights, the flashing green would have been more suitable than flashing yellow for some purposes.  As it is, flashing green is basically wasted, and flashing yellow winds up having different meanings when found as a signal at an intersection vs. as a standalone flashing yellow accompanying a sign (prepare to stop when flashing, urgent message when flashing, etc.).

Agreed.  The flashing yellow light is very ambiguous.  Does it mean "It's a good idea to slow down", "You are required to slow down", "Cross traffic has a flashing red light so you're good to go", "Yield", ......

Yet the flashing green light isn't used, nor are combinations (e.g. steady green ball with flashing yellow ball).

[roadfro]

The flashing yellow light is very ambiguous.  Does it mean "It's a good idea to slow down", "You are required to slow down", "Cross traffic has a flashing red light so you're good to go", "Yield", ......

Try "proceed with caution". Works for any instance of flashing yellow at a signal, whether FYA or red/yellow flash mode.

[PHLBOS]

While many flashing green signals are quite old equipment, there are many out there that are newer signals that were carbon-copy replacements of old ones (like the Margin St. Peabody ones at the Salem line).  I am surprised that they are allowed to stay as flashing green like that, but maybe there isn't any specific language about it that prohibits them being replaced in-kind like that.

That's probably because only the signal-heads were replaced but not the control box.  My guess is that if the control box is replaced, then the signals have to be updated to modern operating standards.

Also common at intersections where there is a flashing green for the main road is that the side street usually has a flashing red in the bottom of the signal (that is, the signal is red, yellow, red from top to bottom).

Red with yellow both in the middle and bottom is also a common sight for pedestrian-activated signals at intersections for the major roadway (the minor intersecting road had red-yellow-red).  The bottom signals, regardless of lens color would be the flashing signal.

Several of Marblehead's traffic signals featured the above (including the Pleasant/School Street signal) until a decade or two ago.  Two of them changed to a more conventional red-yellow-green operations.  To my knowledge, Marblehead never had the steady red & yellow operations for pedestrian crossings (en lieu of a WALK signal).

[kphoger]

The flashing yellow light is very ambiguous.  Does it mean "It's a good idea to slow down", "You are required to slow down", "Cross traffic has a flashing red light so you're good to go", "Yield", ......

Try "proceed with caution". Works for any instance of flashing yellow at a signal, whether FYA or red/yellow flash mode.

I was taught in driver's ed that a green light means 'proceed with caution'.  Case in point.

[Scott5114]

Perhaps someone reacted violently to being confused by a flashing green light?

[PurdueBill]

While many flashing green signals are quite old equipment, there are many out there that are newer signals that were carbon-copy replacements of old ones (like the Margin St. Peabody ones at the Salem line).  I am surprised that they are allowed to stay as flashing green like that, but maybe there isn't any specific language about it that prohibits them being replaced in-kind like that.

That's probably because only the signal-heads were replaced but not the control box.  My guess is that if the control box is replaced, then the signals have to be updated to modern operating standards.

Also common at intersections where there is a flashing green for the main road is that the side street usually has a flashing red in the bottom of the signal (that is, the signal is red, yellow, red from top to bottom).

Red with yellow both in the middle and bottom is also a common sight for pedestrian-activated signals at intersections for the major roadway (the minor intersecting road had red-yellow-red).  The bottom signals, regardless of lens color would be the flashing signal.

Several of Marblehead's traffic signals featured the above (including the Pleasant/School Street signal) until a decade or two ago.  Two of them changed to a more conventional red-yellow-green operations.  To my knowledge, Marblehead never had the steady red & yellow operations for pedestrian crossings (en lieu of a WALK signal).

Yep, the red-yellow-yellow is also common at fire stations as well as some pedestrian ones.  Near my old home in Peabody at the Y-intersection of Lowell St. and Johnson St. was a fun combination of flashers and regular R-Y-G lights.  Westbound, bottom yellow flashers.  On the opposite sides of those, for eastbound Johnson St. ending at Lowell St, red bottom flashers.  West of there on Lowell St. for both directions, R-Y-G signals with Walk signals, one newer (a replacement for an old one) and one original and old, with an additional signal for the exit from the fire station; the fire station can change the signals at the intersection to go all red and the eastbound Lowell St. signal to also go red while westbound Lowell St. stays green to clear traffic.  Finally, on Johnson St. (no street view), regular R-Y-G for a crosswalk, pedestrian-actuated with Walk signals--both old like the other older signals, and painted green for some years now for whatever reason.  All of this is because of the nearby elementary school on Johnson St., the convenience store in the middle of the Y, the fire station across Lowell St. from the store, and the public library branch next door to the fire station.  It's a busy area for pedestrians and vehicles alike.  The variety of signal change possibilities is quite interesting, as is the variety of arrangements (R-Y-Y, R-Y-R, and R-Y-G all together).

I would agree that for sure the controller box on Margin St. is old and thus the new signal heads are just doing the same as the older ones and like you say, if that is updated, flashing green is gone.  Interesting thing about the flashing greens and bottom reds there--check out this street view, making sure to turn 180 degrees to face the other way across the street.  Yes, those are bottom red flashers for a crosswalk!  Push the button to get red and yellow all ways to cross.  (The next time I'm in that area, I'm going to have to get good video of those in action.  They can't live forever and need to be documented.)

I remember back when the area around Peabody Square was redone in the late 80s/early 90s that for a period of time, the side street across from the main Peabody fire station and next to City Hall had two signal heads facing it at its intersection with Lowell St. that were tied into the fire station signals and were first installed Red-Red-Yellow, with the middle red flashing in normal operation.  Fortunately that was eventually fixed.

I must say, being a born-there and trained-there Boston Driver, I was ready to see almost anything!  Woe to the tourists who encounter these crazy things and have never seen anything even close before!

[jwags]

Here in Wisconsin our horizontally mounted signals have the arrows between the solid yellow and the green.  It typically goes from left to right R-Y-YA-GA-G

Here's a pic: http://goo.gl/maps/Xn44

[Scott5114]

The only fire station stoplight I have seen is in Del City. It's a two section light, red 16" and yellow 12". The yellow flashes. It looks ancient...anyone want to guess the vintage?

https://maps.google.com/maps?q=SE+15th+and+Sunnylane+Del+City+OK&hl=en&ll=35.449711,-97.437422&spn=0.007202,0.016469&sll=37.0625,-95.677068&sspn=56.59387,134.912109&hnear=SE+15th+St+%26+S+Sunnylane+Rd,+Del+City,+Oklahoma,+73115&t=m&z=17&layer=c&cbll=35.449706,-97.437294&panoid=aPvSkU32wz2gF5nxHKgl2Q&cbp=12,102.68,,0,2.76

[DaBigE]

Here in Wisconsin our horizontally mounted signals have the arrows between the solid yellow and the green.  It typically goes from left to right R-Y-YA-GA-G

Here's a pic: http://goo.gl/maps/Xn44

Except if the arrows are for a right turn, then it's R-Y-G-YA-GA, just as Figure 4D-18 of the MUTCD depicts.

[jwags]

Here in Wisconsin our horizontally mounted signals have the arrows between the solid yellow and the green.  It typically goes from left to right R-Y-YA-GA-G

Here's a pic: http://goo.gl/maps/Xn44

Except if the arrows are for a right turn, then it's R-Y-G-YA-GA, just as Figure 4D-18 of the MUTCD depicts.

That configuration is at the next signal southbound.

[PHLBOS]

PurdueBill, next time you're in the North Shore; you might want to check out the signals at the Abbott Public Library in Marblehead (along Pleasant St., after the MA 114/129 jct.) for some odd signalhead arrangements.  The signal's a combination of a pedestrain signal w/supplemental heads likely used for when fire trucks from the nearby station depart.

[Mr_Northside]

The flashing yellow light is very ambiguous.  Does it mean "It's a good idea to slow down", "You are required to slow down", "Cross traffic has a flashing red light so you're good to go", "Yield", ......

Try "proceed with caution". Works for any instance of flashing yellow at a signal, whether FYA or red/yellow flash mode.

Here in PA, it's taught that flashing yellow means treat like green, except proceed with more caution.
An arrow means your turn movement is protected (you don't have to yield)

Logically, a Flashing Yellow should then be treated just like a solid green arrow... except you proceed with more caution.
* "proceed with more caution" should not mean automatically expecting to yield.  You expect oncoming traffic to still yield / stop for you

However, it is my understanding that if you turn left at a FYA without yielding to approaching oncoming traffic, bad things might happen... even though you had an arrow.

[roadfro]

The flashing yellow light is very ambiguous.  Does it mean "It's a good idea to slow down", "You are required to slow down", "Cross traffic has a flashing red light so you're good to go", "Yield", ......

Try "proceed with caution". Works for any instance of flashing yellow at a signal, whether FYA or red/yellow flash mode.

I was taught in driver's ed that a green light means 'proceed with caution'.  Case in point.

The distinction is made between "permitted to enter the intersection" (on steady green) versus "permitted to cautiously enter the intersection" (on flashing yellow) in the MUTCD.

Here in PA, it's taught that flashing yellow means treat like green, except proceed with more caution.
An arrow means your turn movement is protected (you don't have to yield)

Logically, a Flashing Yellow should then be treated just like a solid green arrow... except you proceed with more caution.
* "proceed with more caution" should not mean automatically expecting to yield.  You expect oncoming traffic to still yield / stop for you

However, it is my understanding that if you turn left at a FYA without yielding to approaching oncoming traffic, bad things might happen... even though you had an arrow.

A green arrow means your turn movement is protected and you do not have to yield, but this doesn't extend to other arrow colors.

Flashing yellow does not mean that you should expect oncoming traffic to yield to you. Similarly, making a permissive left turn on a circular green does not automatically mean the opposing traffic will yield to your left turn maneuver.

[SignBridge]

Scott, that fire station signal in Del City might be from the 1970's. It's almost identical to the one in front of my neighborhood fire station , erected in 1976. BTW, those lens sizes are 12-inch and 8-inch. Similar signals built today are usually 3-section with (from top-to-bottom) a 12-inch red, 12-inch yellow for the change interval, and 8-inch yellow for the normal flashing mode.

[Scott5114]

Ah, 12/8. I dunno why I thought it was 16/12...

[SignBridge]

(Chuckle!) Maybe you thinking of letter sizes on the BGS's?! 

[kphoger]

The flashing yellow light is very ambiguous.  Does it mean "It's a good idea to slow down", "You are required to slow down", "Cross traffic has a flashing red light so you're good to go", "Yield", ......

Try "proceed with caution". Works for any instance of flashing yellow at a signal, whether FYA or red/yellow flash mode.

I was taught in driver's ed that a green light means 'proceed with caution'.  Case in point.

The distinction is made between "permitted to enter the intersection" (on steady green) versus "permitted to cautiously enter the intersection" (on flashing yellow) in the MUTCD.

This is sort of confirming my assertion that the meaning of a flashing yellow is ambiguous.  I really don't think we should be expecting people to read the MUTCD in order to know what the difference is between two colors of stoplights in certain circumstances (the difference between a solid green ball and a flashing yellow ball is not the same as the difference between a solid green arrow and a flashing yellow arrow)–especially when phases like flashing green and most color combinations aren't being used at all.

[roadfro]

The flashing yellow light is very ambiguous.  Does it mean "It's a good idea to slow down", "You are required to slow down", "Cross traffic has a flashing red light so you're good to go", "Yield", ......

Try "proceed with caution". Works for any instance of flashing yellow at a signal, whether FYA or red/yellow flash mode.

I was taught in driver's ed that a green light means 'proceed with caution'.  Case in point.

The distinction is made between "permitted to enter the intersection" (on steady green) versus "permitted to cautiously enter the intersection" (on flashing yellow) in the MUTCD.

This is sort of confirming my assertion that the meaning of a flashing yellow is ambiguous.  I really don't think we should be expecting people to read the MUTCD in order to know what the difference is between two colors of stoplights in certain circumstances (the difference between a solid green ball and a flashing yellow ball is not the same as the difference between a solid green arrow and a flashing yellow arrow)–especially when phases like flashing green and most color combinations aren't being used at all.

I'm still trying to understand what about the flashing yellow is ambiguous, and how green is interpreted as "proceed with caution"...

The difference between a solid circular green & flashing circular yellow versus a solid green arrow and flashing yellow arrow is not all that different. A flashing yellow, regardless of circular or arrow, is that you are permitted to enter the intersection cautiously to proceed through, yielding if necessary to any other traffic legally in the intersection. The flashing yellow arrow allows you to make that movement, after yielding if necessary; the flashing circular yellow lets you go straight through or turn, after yielding if necessary. If anything, the meaning of a permissive left turn on circular green is the most ambiguous, which is one of the reasons for development of the FYA in the first place.

[Mr_Northside]

The difference between a solid circular green & flashing circular yellow versus a solid green arrow and flashing yellow arrow is not all that different.

I'd have to disagree.  There's no real difference between a solid curricular ("ball") green & a flashing yellow ball.  However the difference between expecting to not have to yield to oncoming traffic (SGA) and having to yield (FYA) is a pretty noticeable difference.

A flashing yellow, regardless of circular or arrow, is that you are permitted to enter the intersection cautiously to proceed through, yielding if necessary to any other traffic legally in the intersection. The flashing yellow arrow allows you to make that movement, after yielding if necessary; the flashing circular yellow lets you go straight through or turn, after yielding if necessary.

A flashing yellow ball sounds right for that.  It's the addition of the arrow that might make it "ambiguous" - (Though I don't want to speak for the other poster who was using that term)

If anything, the meaning of a permissive left turn on circular green is the most ambiguous, which is one of the reasons for development of the FYA in the first place.

I guess that's what irks me about this "issue".  Maybe it's just a sign of how dumb most of the general motoring public is.  There are plenty of simple traffic signals that don't have any arrows at all. Just "circulars", and most people get that the absence of an arrow means you yield to oncoming traffic.  In general, you always have to yield to oncoming traffic.  Not just at signals, but in general.  A 4-way stop (at a 4-way intersection), of course is an exception where you can turn left when it's your "turn"... 
Another exception is at a signal that has arrows, which indicate you have the right-of-way to turn, because they're arrows!

I guess if they wanted to replace the doghouse, I wouldn't raise a stink (on a roads message board) if they just had a F-Y-[ball (or "circular")], instead of an arrow.

Having to yield to oncoming traffic when you have an arrow (even a yellow one that is flashing) just seems very oxymoronic to me.

/rant.

[roadfro]

The difference between a solid circular green & flashing circular yellow versus a solid green arrow and flashing yellow arrow is not all that different.

I'd have to disagree.  There's no real difference between a solid curricular ("ball") green & a flashing yellow ball.  However the difference between expecting to not have to yield to oncoming traffic (SGA) and having to yield (FYA) is a pretty noticeable difference.

A flashing yellow, regardless of circular or arrow, is that you are permitted to enter the intersection cautiously to proceed through, yielding if necessary to any other traffic legally in the intersection. The flashing yellow arrow allows you to make that movement, after yielding if necessary; the flashing circular yellow lets you go straight through or turn, after yielding if necessary.

A flashing yellow ball sounds right for that.  It's the addition of the arrow that might make it "ambiguous" - (Though I don't want to speak for the other poster who was using that term)

If anything, the meaning of a permissive left turn on circular green is the most ambiguous, which is one of the reasons for development of the FYA in the first place.

I guess that's what irks me about this "issue".  Maybe it's just a sign of how dumb most of the general motoring public is.  There are plenty of simple traffic signals that don't have any arrows at all. Just "circulars", and most people get that the absence of an arrow means you yield to oncoming traffic.  In general, you always have to yield to oncoming traffic.  Not just at signals, but in general.  A 4-way stop (at a 4-way intersection), of course is an exception where you can turn left when it's your "turn"... 
Another exception is at a signal that has arrows, which indicate you have the right-of-way to turn, because they're arrows!

I guess if they wanted to replace the doghouse, I wouldn't raise a stink (on a roads message board) if they just had a F-Y-[ball (or "circular")], instead of an arrow.

Having to yield to oncoming traffic when you have an arrow (even a yellow one that is flashing) just seems very oxymoronic to me.

/rant.

What I'm getting from this interpretation is the thought that the presence of an arrow signal assigns right of way. That is not the case, and where I'm guessing the ambiguity comes from. An arrow signal is designed to control certain movements heading in the direction of the arrow, but doesn't assign right of way any more than a signal with circular indications. (I will concede the point that a green arrow does provide a protected movement, but that is separate from right of way).

The flaw I see in your argument is that "most people get that the absence of an arrow means you yield to oncoming traffic". The study that led to the adoption of the FYA design showed that many drivers found a circular green over their left turn lane to be ambiguous and often interpreted it as a "go" when they should yield first--remember, many people drive with the notion that "green means go". This is what led to the 2009 MUTCD adopting the stance that no circular indications should appear over a left lane or for dedicated left turn signal heads, instead favoring FYA. Testing showed FYA to be more intuitively understood by drivers, and would generate more "fail safe" responses when not understood.

[codyg1985]

An arrow signal is designed to control certain movements heading in the direction of the arrow, but doesn't assign right of way any more than a signal with circular indications. (I will concede the point that a green arrow does provide a protected movement, but that is separate from right of way).

As the case with a red arrow. You aren't permitted to turn left with a left red arrow indication.

[Central Avenue]

I guess if they wanted to replace the doghouse, I wouldn't raise a stink (on a roads message board) if they just had a F-Y-[ball (or "circular")], instead of an arrow.

That's been done, actually. It's called Dallas phasing. I think this photo (by fellow forumgoer US 71) demonstrates the problem with this setup pretty well:



Yes, most people, if they take the time to think it through, will arrive at the correct conclusion--that a green ball indicates a permissive left turn. But in reality, people don't drive that way--they see the lights, and make an automatic, split-second decision about what the "right" thing to do is. With this setup, too many people saw that the other two lanes were being held by red, and automatically assumed the green over exclusively the left lane meant it was a protected turn.

Ironically, if this setup were more common, this would probably be much less of an issue, because people would have become accustomed to the correct meanings.

[agentsteel53]

I'm assuming, in that photo, oncoming traffic has green to go straight and a protected left?

I've seen that scenario only a handful of times in my life - and each time, it had the small informative sign.

would a flashing yellow arrow be appropriate in this context?  I've only seen flashing yellow paired with green for the forward directions, never with red.