I was wondering which was more common back in the days before flashing yellow arrows. Listing the states I know:
* Alabama: Doghouse
* Alaska: Doghouse
* Arizona: Varies by city
* Arkansas: 5 section
* California: Both
* Colorado: Doghouse or Offset Doghouse
* Connecticut
* DC: Both
* Idaho: Does not seem to have permissive-protected lefts with a separate head except for FYA installations
* Illinois: 5 section
* Indiana: Doghouse
* Iowa: Varies by city, though the doghouse seems to be more common
* Kansas: Varies by city
* Kentucky: Doghouse
* Maine: Appears to be Doghouse or bimodal 4 section
* Michigan: Doghouse or flashing red ball
* Mississippi: Doghouse
* Missouri: Doghouse, though some older non-state signals had 5-sectons
* Montana: Varies by city
* Nebraska: Offset Doghouse, though some older signals used 5-sections
* Nevada: Doghouse
* New Mexico: 5 section
* New York (outside NYC): Doghouse
* North Dakota: Doghouse
* Ohio: Doghouse
* Pennsylvania: Doghouse
* Rhode Island: Does not seem to have permissive-protected lefts
* South Dakota: 5 section
* Tennessee: Doghouse, older signals used Offset Doghouse
* Utah: Doghouse
* Virginia: Doghouse
* West Virginia: Offset Doghouse
* Wisconsin: 5 section
* Wyoming: Offset Doghouse
(Edited to update list based on posts and using GSV)
My experiences are that most states use doghouses, with the exceptions you listed plus Minnesota.
Michigan, Delaware, and Maryland are the only states that used a flashing red ball for permissive left turns. Here is an example:
I love the Michigan signals. Especially when they start off as green arrows, and end with a green arrow.
Washington and Oregon used to use 4-Section lights, and the doghouse/5-section signals starting around 2000.
A big advantage of the Michigan setup is that drivers who are unable to find a gap in traffic during the permissive left-turn phase can complete their turn during the protected lagging left-turn phase. This prevents drivers from getting "stuck" in the middle of the intersection.
The FYA setup allows for much greater flexibility which can often lead to complicated left-turn phasing. The video below shows a lead-lag FYA intersection where one direction has a protected leading left-turn while the opposing direction has a protected lagging left-turn:
Watching 1:30-1:35 in the video, the left-turn is flashing yellow as the thru is clearing down. Even though this is not a yellow trap, it could be argued that it is a "perceived yellow trap" . A driver sees in their peripheral vision that the thru lane is changing to yellow and quickly glances up to see a solid yellow left-turn arrow. Unfortunately, the driver glanced up during the 0.5 second flash on as opposed to the 0.5 second flash off and they mistakenly believed the left turn was terminating. This "perceived yellow trap" would be just as dangerous as an actual yellow trap. A traffic engineer could easily argue the theory of why the operation from 1:30-1:35 is safe, but in reality is it?
West Virginia = Variation on the Doghouse where the red light is not in the middle, but rather to the right over top the yellow ball and green ball (http://farm3.static.flickr.com/2567/5749218646_9b6237da94_z.jpg)
Virginia = Doghouse with few exceptions (one or two intersections in VA Beach, redundant side-mounted signals in Arlington), though 5-section towers used to be used with some regularity for protected/permissive right turn signals. Very few of these remain. Even most VDOT-installed side-mounted protected/permissive signals are doghouses astro-braced to the pole or pedestal despite how odd they look. In the extreme southwest portion of the state (Bristol, etc.), the WV variation of the doghouse is used.
Pennsylvania = Doghouse with few exceptions, even when side-mounted. Even many of their 4-section signals are of this style (i.e. the green arrow and green ball are next to each other below the yellow and red ball).
Ohio = Same as Pennsylvania
South Dakota = 5-Section towers. I've never seen a doghouse.
California = Both -- Overhead are usually doghouse, side-mounted are always 5-section towers.
Washington, DC = Same as California
Maryland = Doghouse for most overhead signals, though some supplemental signals on the close side of the intersection sometimes use an odd combination of 12-inch signals for the arrows and 8-inch signals for the red, yellow, and green balls, in a WV-modified doghouse formation. (http://farm5.staticflickr.com/4047/4416770363_244aea0434_o.jpg). I've seen 5-section towers used for side-mounted signals, when used.
Quote from: dfnva on August 18, 2013, 10:24:34 PM
California = Both -- Overhead are usually doghouse, side-mounted are always 5-section towers.
Based on my observations, doghouse signals are extremely rare in California because most left turns are protected rather than permitted. 5-section towers are commonly used for protected right turns.
Arkansas primarily uses 5 section signals.
Missouri is a mix of Doghouse (overhead) and 5 section signals (side mount)
Virginia uses primarily doghouses.
As for Charlottesville, it's
Neither.Charlottesville uses nothing but 4-section signals with bimodal arrows.
Examples:Right
Left
Diagonal (skip to 0:42)
There is only 1 exception, an inline 5-section 3M signal (http://www.youtube.com/watch?v=D-svQHUwiPA).
Alabama and Mississippi use doghouses for the most part unless the signals are mounted horizontally.
Quote from: dfnva on August 18, 2013, 10:24:34 PM
West Virginia = Variation on the Doghouse where the red light is not in the middle, but rather to the right over top the yellow ball and green ball (http://farm3.static.flickr.com/2567/5749218646_9b6237da94_z.jpg)
Tennessee used to use this style, and there are still examples of this throughout the state, but the state has now switched to the traditional doghouse.
Upstate NY almost exclusively uses doghouses. Fully protected lefts are rare here (but becoming more common, sadly).
Quote from: Signal on August 19, 2013, 11:59:26 AM
Virginia uses primarily doghouses.
As for Charlottesville, it's Neither.
Charlottesville uses nothing but 4-section signals with bimodal arrows.
Examples:
Right (video is NOT sideways)
Left
Diagonal (skip to 0:42)
There is only 1 exception, an inline 5-section 3M signal (http://www.youtube.com/watch?v=D-svQHUwiPA).
The most obvious VA exception I forgot about. Did Charlottesville use doghouses for their installs before the signals with bimodal arrows were installed? The earliest I recall considering the signals of Charlottesville was around 1999, marveling at the rare use (for VA) of the bimodal arrows. I could've sworn I saw a doghouse somewhere (not the 3M) but it may have been in Albemarle County.
Come to think of it Illinois uses bimodal arrows (4 light towers) in some places as well, particularly around Champagne/Urbana if my memory serves me well.
The first time I saw one was in Bethesda, MD in the mid-1990s... is that about when bimodal arrows started being installed?
I don't remember where now (Kansas City or St Joseph ?), but I've seen mast signals with a bimodal 3M arrow for Left Turns.
Besides the examples mentioned thus far, I'd like to add that New Mexico uses a 5-lens mounted horizontally like Wisconsin does.
In the Minnesota Notes thread, it's been noted that MnDOT is about to change their standard to either the FYA or the doghouse (depending on the specific situation).
New Jersey has a lot of bimodal arrows.
I've never seen a flashing red ball used in Maryland. Every installation I've seen where left turns were permissible on a red and a doghouse wasn't used, they use a flashing red arrow, not a ball.
I recall the Syracuse area having a fair number of protected-only left turns 8-10 years ago.
The thing I found most interesting about the Charlottesville videos linked above was the weird right-on-red sign on 10th Street at Grady Avenue. Street View with a curb-mounted sign may be seen here. (http://goo.gl/maps/A2Qz9) I can't say I've ever seen a sign like that before, including at that intersection (the sign was definitely not there when I attended UVA because I'd remember something like that). The message is straightforward enough, though I wonder if it might be a bit wordy when you see it in person. If I remember, I will have to drive past it when we go to a football game this fall.
(That whole intersection complex was always weird. Going west on Preston Avenue, the light would turn red for traffic turning left onto Grady but stay green to continue straight on Preston. Immediately afterwards the intersection of Preston and 10th had a flashing yellow light that's now gone. So anyone who knew the area would go straight on Preston, hang a left at the flashing yellow, and then go right on red onto Grady. Saved you a long wait at the left-turn light.)
A lot of Charlottesville's left-turn lights always had unusual phasing compared to the rest of Virginia as well. I believe "mtantillo" of this forum once told me (somewhere else) that the phasing is called "lead-lag." Using Emmet Street at Ivy Road as an example: (1) Northbound Emmet gets a green ball to go straight and a green left arrow, southbound Emmet has a red. (2) The green arrow turns off and southbound Emmet gets a green ball but no turn arrow (so both directions are going straight). (3) Northbound Emmet's light turns completely red and southbound Emmet gets the green left-turn arrow along with the green ball. This is highly non-standard pretty much everywhere else I've driven in Virginia (normally both directions get the left arrows at the beginning of the light cycle). I'm not saying it's never used elsewhere in Virginia, mind you–I'm just saying it's remarkably common in Charlottesville compared to everywhere else in the Commonwealth.
Quote from: US71 on August 20, 2013, 08:22:18 AM
I don't remember where now (Kansas City or St Joseph ?), but I've seen mast signals with a bimodal 3M arrow for Left Turns.
Rockford, Illinois still has several. Joliet, Illinois used to have a bunch of these until the early 1990s. They have since been replaced with five signal head towers.
Quote from: 1995hoo on August 20, 2013, 09:45:51 AM
A lot of Charlottesville's left-turn lights always had unusual phasing compared to the rest of Virginia as well. I believe "mtantillo" of this forum once told me (somewhere else) that the phasing is called "lead-lag." Using Emmet Street at Ivy Road as an example: (1) Northbound Emmet gets a green ball to go straight and a green left arrow, southbound Emmet has a red. (2) The green arrow turns off and southbound Emmet gets a green ball but no turn arrow (so both directions are going straight). (3) Northbound Emmet's light turns completely red and southbound Emmet gets the green left-turn arrow along with the green ball. This is highly non-standard pretty much everywhere else I've driven in Virginia (normally both directions get the left arrows at the beginning of the light cycle). I'm not saying it's never used elsewhere in Virginia, mind you–I'm just saying it's remarkably common in Charlottesville compared to everywhere else in the Commonwealth.
Are the left turns permissive? A lead-lag can be dangerous as it has the potential (depending how the signal is set up) to lead to the yellow trap. The video i posted previously is an example of a FYA lead-lag setup. The protected turn is allowed to skip if nobody is detected which leads to some interesting phasing. The FYA effectively eliminates the possibility of the yellow trap but it can still lead to what i call the "perceived yellow trap". Does anyone think the signal phasing from 1:30 through 1:35 in the video could be confusing to some drivers and lead to a perceived yellow trap?
what is the yellow trap? assuming that, because your straight-through travel lanes are getting red, so are the opposing straight-through travel lanes? and therefore that oncoming traffic is gonna stop?
dangerous assumption. first off, you cannot assume anything about the opposing signal. second, if you think oncoming traffic is gonna stop when they get a yellow, instead of flooring it, you have not driven in any major city on the coasts.
Quote from: tradephoric on August 20, 2013, 11:55:03 AM
Quote from: 1995hoo on August 20, 2013, 09:45:51 AM
A lot of Charlottesville's left-turn lights always had unusual phasing compared to the rest of Virginia as well. I believe "mtantillo" of this forum once told me (somewhere else) that the phasing is called "lead-lag." Using Emmet Street at Ivy Road as an example: (1) Northbound Emmet gets a green ball to go straight and a green left arrow, southbound Emmet has a red. (2) The green arrow turns off and southbound Emmet gets a green ball but no turn arrow (so both directions are going straight). (3) Northbound Emmet's light turns completely red and southbound Emmet gets the green left-turn arrow along with the green ball. This is highly non-standard pretty much everywhere else I've driven in Virginia (normally both directions get the left arrows at the beginning of the light cycle). I'm not saying it's never used elsewhere in Virginia, mind you–I'm just saying it's remarkably common in Charlottesville compared to everywhere else in the Commonwealth.
Are the left turns permissive? A lead-lag can be dangerous as it has the potential (depending how the signal is set up) to lead to the yellow trap. The video i posted previously is an example of a FYA lead-lag setup. The protected turn is allowed to skip if nobody is detected which leads to some interesting phasing. The FYA effectively eliminates the possibility of the yellow trap but it can still lead to what i call the "perceived yellow trap". Does anyone think the signal phasing from 1:30 through 1:35 in the video could be confusing to some drivers and lead to a perceived yellow trap?
The one I mentioned before is definitely permissive, using the four-section signal mentioned previously. Here's a Street View of the intersection I referenced: http://goo.gl/maps/L1TXO
I am not positive they still use lead-lag at that particular intersection because nowadays I'm usually there on football game days and the cops override the signal to flash yellow. Either way, though, that particular cycle (coupled with permissive left turns) was peculiar to Charlottesville among Virginia jurisdictions I've visited regularly.
Quote from: dfnva on August 19, 2013, 10:06:22 PM
The most obvious VA exception I forgot about. Did Charlottesville use doghouses for their installs before the signals with bimodal arrows were installed? The earliest I recall considering the signals of Charlottesville was around 1999, marveling at the rare use (for VA) of the bimodal arrows. I could've sworn I saw a doghouse somewhere (not the 3M) but it may have been in Albemarle County.
Only within city limits are there bimodal arrows.
Inside Charlottesville, there are no 5-section signals (besides the 3M). Only 4-sections with bimodal arrows.
Outside Charlottesville, there are no 4-section w/ bimodal arrows. Only doghouses.
The closest doghouse signals in Charlottesville are at JPJ, outside of city limits.
Quote
The first time I saw one was in Bethesda, MD in the mid-1990s... is that about when bimodal arrows started being installed?
I honestly know little about bimodal arrow 'history'.
Before LEDs were used for signals, there were fiber-optic bimodal arrows.
Right now, all bimodal arrows in Charlottesville are LED except for 1 fiber-optic arrow (and it is currently not functioning).
In Charlottesville, there are two versions of LED bimodal arrows.
This arrow has clear glass, so you can see how it works. This video shows it changing close up and from a distance, then shows them in slow motion. You can see how there are alternatingly-colored LED lights in rows to form the arrow, so it noticably shifts a little when changing color.
This is the other version, with a frosted front. This has a more incandescent look, and you can't see any shift.
Here is a picture of the last fiber-optic bimodal arrow.
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Ffarm4.staticflickr.com%2F3671%2F9302863941_b6ab76f823_z.jpg&hash=d50e8d5602f7be1b0576f649541d30bd4a7d5f08) (http://www.flickr.com/photos/94611454@N02/9302863941/)
Fiber Optic Bimodal Arrow (http://www.flickr.com/photos/94611454@N02/9302863941/) by Signals Unlimited (http://www.flickr.com/people/94611454@N02/), on Flickr
Quote from: 1995hoo on August 20, 2013, 09:45:51 AM
Using Emmet Street at Ivy Road as an example: (1) Northbound Emmet gets a green ball to go straight and a green left arrow, southbound Emmet has a red. (2) The green arrow turns off and southbound Emmet gets a green ball but no turn arrow (so both directions are going straight). (3) Northbound Emmet's light turns completely red and southbound Emmet gets the green left-turn arrow along with the green ball.
That intersection no longer does that. There are two ways it cycles.
[1] If there is someone waiting to turn left NB on Emmet, but noone waiting SB on Emmet (it cycles vice versa too):
- NB Emmet gets green left arrow & thru signals. EB Ivy gets green right arrow.
- NB Emmet & EB Ivy's arrows go away. Both directions on Emmet St now have green thru signals and permissive left turn.
[2] If there is someone waiting to turn left in both directions on Emmet:
- NB & SB Emmet have green left arrows; red thru signals. EB & WB Ivy have green right arrows; red thru signals.
- SB Emmet's left arrow goes away. WB Ivy's right arrow goes away.
NB Emmet now has green arrow & thru signals. (EB Ivy still has green right). SB Emmet has all red. - NB Emmet & EB Ivy's arrows go away. Both directions on Emmet St now have green thru signals and permissive left turn. Both directions on Ivy have all red.
Another interesting bimodal use in Charlottesville is redundant, in a 3-section signal. It cycles like any protected turn signal, but the yellow arrow & yellow ball always come on at the same time.
That particular signal is now gone. There are only 2 remaining with that configuration.
EDIT: never mind
Quote from: Signal on August 20, 2013, 12:37:07 PM
....
Quote from: 1995hoo on August 20, 2013, 09:45:51 AM
Using Emmet Street at Ivy Road as an example: (1) Northbound Emmet gets a green ball to go straight and a green left arrow, southbound Emmet has a red. (2) The green arrow turns off and southbound Emmet gets a green ball but no turn arrow (so both directions are going straight). (3) Northbound Emmet's light turns completely red and southbound Emmet gets the green left-turn arrow along with the green ball.
That intersection no longer does that. There are two ways it cycles.
....
That's a big improvement. I recall seeing any number of near-misses over the years when people, mostly non-locals who weren't aware that Charlottesville used this peculiar phasing, would be hit by a yellow trap, essentially–they'd be waiting on the permissive green during the "both directions green ball" phase, see their side go red, and proceed to turn under the erroneous assumption the other side was also going red. (This is one of the problems with the habit of pulling out into the intersection to wait during a permissive green cycle.)
Quote from: agentsteel53 on August 20, 2013, 12:05:50 PM
what is the yellow trap? assuming that, because your straight-through travel lanes are getting red, so are the opposing straight-through travel lanes? and therefore that oncoming traffic is gonna stop?
What is the yellow trap? A "yellow trap" occurs when a driver, who has a permissive left turn phase and is waiting for a gap in the opposing through movement, sees a yellow indication for both through and left turns, and mistakenly thinks that the signals for the opposing direction have become yellow simultaneously.
The operation at 1:30-1:35 in the video is NOT a yellow trap, but drivers may be confused when they see the thru lanes turning yellow. The driver may automatically assume that the thru must terminate simultaneous with the opposing thru... or they may glance up for a split second — less than the 0.5 second flash rate - to see that the left turn signal is solid yellow, not realizing that it is still in fact blinking. The intersection in the video is at 9 Mile & Harper in Macomb County, Michigan. The woman who is speaking in the video was involved in a crash on 2/15/11 while attempting to make a left turn traveling NB Harper. You can hear her adamantly saying that she made a left turn while all three signal heads were turning yellow together (listen to her at the very end of the video). In the UD-10 report, the officer stated that the opposing thru driver entered the intersection while the light was green. Maybe in her mind, the left turn had a solid yellow when in fact it was still flashing yellow. It's similar to driving through a signal in flash and for a moment believing you're about to run the yellow light (for example, when you are driving behind a large truck and can't see the flashing signal until the last moment).
The phasing is complicated by the fact that the very next cycle, the thru and left turn does terminate together. This is due to the fact that nobody was detected in the opposing left turn lane and that phase was allowed to skip. It's confusing to drivers when the signal phasing is changing on a cycle by cycle basis as drivers never really know what to expect.
there's an easy solution.
first look at the lights. then look at the drivers.
Quote from: agentsteel53 on August 20, 2013, 05:43:06 PM
there's an easy solution.
first look at the lights. then look at the drivers.
You'd need brake lights on the front of cars to be sure if oncoming traffic is coming to a stop.
Another simple solution: don't let a turn yellow and any conflicting greens to overlap.
These five-section lights for left turns were very common in Florida until the 1990s, when many of the intersections were widened, creating twin turning lanes, each with their own 3-section signals. It's also become more common for the intersections to be modified for protected signals on roads with higher traffic counts.
They're still a common enough sight on many four-lane roads, or two-lane roads with heavy traffic.
For many years, New York City only used a green arrow indication for protected turn movements. In addition to that, the leading protected turn movement was the ideal sequence used. The amber arrow indication did not appear until perhaps the 1970s there. Even so, the original sequence was still widely used. It eventually disappeared for the most part, and some signalized intersections, as a handful, throughout New York City continue to use it. One that I am aware of exists on Staten Island.
Today, N.Y.C.D.O.T. commonly uses the G.A./A.A. head for a leading protected turn movement (commonly left). Over the years, original sections that only used green arrow indications were connected with additional heads that show amber indications.
Perhaps you could consider the set-up as a "doghouse" of some sorts, but New York City tends to place an ordinary 8" head with a 12-12 head next to it in a cluster.
It appears at least western Kentucky uses doghouses.
Regarding the perceived yellow trap when a flashing yellow arrow is used with lead-lag phasing, if there really is a safety issue with this, I would have expected one or more agencies to have noticed it by now.
Quote from: 1995hoo on August 20, 2013, 09:45:51 AM
The thing I found most interesting about the Charlottesville videos linked above was the weird right-on-red sign on 10th Street at Grady Avenue. Street View with a curb-mounted sign may be seen here. (http://goo.gl/maps/A2Qz9) I can't say I've ever seen a sign like that before, including at that intersection (the sign was definitely not there when I attended UVA because I'd remember something like that). The message is straightforward enough, though I wonder if it might be a bit wordy when you see it in person. If I remember, I will have to drive past it when we go to a football game this fall.
(That whole intersection complex was always weird. Going west on Preston Avenue, the light would turn red for traffic turning left onto Grady but stay green to continue straight on Preston. Immediately afterwards the intersection of Preston and 10th had a flashing yellow light that's now gone. So anyone who knew the area would go straight on Preston, hang a left at the flashing yellow, and then go right on red onto Grady. Saved you a long wait at the left-turn light.)
A lot of Charlottesville's left-turn lights always had unusual phasing compared to the rest of Virginia as well. I believe "mtantillo" of this forum once told me (somewhere else) that the phasing is called "lead-lag." Using Emmet Street at Ivy Road as an example: (1) Northbound Emmet gets a green ball to go straight and a green left arrow, southbound Emmet has a red. (2) The green arrow turns off and southbound Emmet gets a green ball but no turn arrow (so both directions are going straight). (3) Northbound Emmet's light turns completely red and southbound Emmet gets the green left-turn arrow along with the green ball. This is highly non-standard pretty much everywhere else I've driven in Virginia (normally both directions get the left arrows at the beginning of the light cycle). I'm not saying it's never used elsewhere in Virginia, mind you–I'm just saying it's remarkably common in Charlottesville compared to everywhere else in the Commonwealth.
I never knew this was called lead lag, but I've only seen it in VA when one or two directions of a street have double left turn lanes so that there's room for the protected left turn to be completed safely.
Some examples:
* VA-28/Centreville Rd at Liberia Ave. in Manassas
* VA-234/Pr. William Pkwy at SR-674/Wellington Rd in Manassas
There are other intersections that should have this because of near misses --- VA-234-Bus/Sudley Rd and SR-1566/Sudley Manor Dr comes to mind.
Quote from: Revive 755 on August 20, 2013, 09:04:44 PM
Regarding the perceived yellow trap when a flashing yellow arrow is used with lead-lag phasing, if there really is a safety issue with this, I would have expected one or more agencies to have noticed it by now.
The Southeast Michigan Counsel of Governors (SEMCOG) collects 10 years of crash data for intersections throughout the region and publishes the data on their website. Previous to the FYAs, Macomb County used the flashing red ball for permissive left turns. When you compare the 3 years of before and after crash data, there is a 20% increase in injury accidents at the FYA intersections. Other counties in the region have seen similar trends of increased injury accidents at FYA intersections. The safety of FYAs became a hot topic last year when Oakland County Executive L. Brooks Patterson was involved in a serious accident at a FYA in August of 2012. Patterson nearly died in the accident and his driver, James Cram, was left a quadriplegic.
I have no idea if the increase in injury accidents at FYAs throughout the region is due to the "perceived yellow trap". It should be noted that this trap can be seen in not just lead-lag, but also in lag-lag where one of the lagging left turns is allowed to skip when no vehicles are being detected. Most of the FYAs in Macomb County is set up for lag-lag with the left turn phases allowed to skip.
QuoteA lot of Charlottesville's left-turn lights always had unusual phasing compared to the rest of Virginia as well. I believe "mtantillo" of this forum once told me (somewhere else) that the phasing is called "lead-lag." Using Emmet Street at Ivy Road as an example: (1) Northbound Emmet gets a green ball to go straight and a green left arrow, southbound Emmet has a red. (2) The green arrow turns off and southbound Emmet gets a green ball but no turn arrow (so both directions are going straight). (3) Northbound Emmet's light turns completely red and southbound Emmet gets the green left-turn arrow along with the green ball. This is highly non-standard pretty much everywhere else I've driven in Virginia (normally both directions get the left arrows at the beginning of the light cycle). I'm not saying it's never used elsewhere in Virginia, mind you–I'm just saying it's remarkably common in Charlottesville compared to everywhere else in the Commonwealth.
Yes, that sounds like lead-lag, though lead-lag is (almost always) applied to protected-only left situations and not phasing that includes a permitted left. There is a fair amount of it in both Northern Virginia (I lived right next to one on Route 1/Huntington Ave) and also in Hampton Roads (especially in Virginia Beach).
Quote from: froggie on August 21, 2013, 02:23:35 AM
QuoteA lot of Charlottesville's left-turn lights always had unusual phasing compared to the rest of Virginia as well. I believe "mtantillo" of this forum once told me (somewhere else) that the phasing is called "lead-lag." Using Emmet Street at Ivy Road as an example: (1) Northbound Emmet gets a green ball to go straight and a green left arrow, southbound Emmet has a red. (2) The green arrow turns off and southbound Emmet gets a green ball but no turn arrow (so both directions are going straight). (3) Northbound Emmet's light turns completely red and southbound Emmet gets the green left-turn arrow along with the green ball. This is highly non-standard pretty much everywhere else I've driven in Virginia (normally both directions get the left arrows at the beginning of the light cycle). I'm not saying it's never used elsewhere in Virginia, mind you–I'm just saying it's remarkably common in Charlottesville compared to everywhere else in the Commonwealth.
Yes, that sounds like lead-lag, though lead-lag is (almost always) applied to protected-only left situations and not phasing that includes a permitted left. There is a fair amount of it in both Northern Virginia (I lived right next to one on Route 1/Huntington Ave) and also in Hampton Roads (especially in Virginia Beach).
That may be why (as another poster verified) the City of Charlottesville got rid of it at the corner of Emmet and Ivy. That particular intersection also sees a lot of pedestrian and bike traffic, obviously, due to the University being directly adjacent to both streets. So having people encountering a "yellow trap" there is probably all the more dangerous if there's heavy pedestrian traffic that would be put at risk if a turning vehicle were broadsided by a car going 35 mph.
But anyway, regarding it in the rest of Virginia, I believe I acknowledged it's used; my point was just that Charlottesville seemed to have a disproportionate amount of it concentrated in one area compared to the rest of the Commonwealth.
I actually encountered a strange one this morning after dropping of Ms1995hoo at the Van Dorn Metrorail–I looped around on Metro Road to southbound Van Dorn and got a red light just as I approached the stop bar; the northbound side was already green and then their green arrow came on after our red. The reason I say it's strange is that almost every other time I go through there, it's a more conventional cycle with protected left turns for both directions at the leading end of the light cycle. I think I've seen the tail-end green arrow maybe one or two other times (and I've lived in Kingstowne for 11 years, so I use Van Dorn
constantly) and there seems to be little rhyme or reason to when it does it. Weird stuff.
Here is a list of FYA intersections in Macomb County. Injury accidents have increased by 30% when comparing the before/after crash data. All data obtained through SEMCOG:
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fi478.photobucket.com%2Falbums%2Frr144%2Ftradephoric%2FTransportation%2520Pictures%2FRandom%2FMCFYA2_zpsd7aed911.jpg%3Ft%3D1377098616&hash=5acfd0c0720169ed4efc582e33bf0864bdcaea21)
Although I grew up in a state with 5-section signals (as the OP stated), it seems to me that doghouses are more common in the nation as a whole.
Quote from: tradephoric on August 20, 2013, 11:55:03 AM
The FYA effectively eliminates the possibility of the yellow trap but it can still lead to what i call the "perceived yellow trap". Does anyone think the signal phasing from 1:30 through 1:35 in the video could be confusing to some drivers and lead to a perceived yellow trap?
I don't think this leads to a "perceived yellow trap". One of the features of the FYA display, whether the standard 4-section (as shown) or 3-section variant (with shared FYA & steady green arrow bottom section) is the separation of the FYA and the normal yellow arrow. The visual jump between different signal sections and yellow arrows should be the cue to the left turning driver that they need to make a decision...the through traffic signals should not be a factor.
But only if they notice the light. If they're already in the intersection waiting for a gap in traffic, it's very easy to not notice a light becoming steady yellow rather than flashing yellow.
Tradephoric was saying that a quick glance at the signal head might cause one to inadvertently assume a flashing yellow was becoming steady. I assert that if you make a quick glance and note that the yellow arrow has jumped sections, then that's when you'd need to worry--if the yellow is still in the same section as where it was flashing before, there's no need to worry. It's a lot more noticeable that a light has changed sections than it is to switch from flashing to steady in the same signal section. This is why I prefer the 4-section FYA to the 3-section variant.
Quote from: roadfro on September 01, 2013, 03:42:29 AM
Tradephoric was saying that a quick glance at the signal head might cause one to inadvertently assume a flashing yellow was becoming steady. I assert that if you make a quick glance and note that the yellow arrow has jumped sections, then that's when you'd need to worry--if the yellow is still in the same section as where it was flashing before, there's no need to worry. It's a lot more noticeable that a light has changed sections than it is to switch from flashing to steady in the same signal section. This is why I prefer the 4-section FYA to the 3-section variant.
Agreed, and that's why the MUTCD shows a separate section for the FYA from the SYA in its signal diagrams.
Colorado was mostly doghouse (probably as an add-on to the old 12-8-8 signals hanging from overhead wires in places such as Denver), then had some 4-sections and mostly 5-sections that were side-mounted (or center-mounted in the medians). Denver had some interesting ones with the normal 8-8-8 three section signals with two 12-inch signals added to the bottom for the green and yellow turn arrows. Now Aurora is installing the FYA (usually with four sections, some with three), Denver has installed their first two FYAs, and I have not heard of any other ones...yet...in other cities.
Quote from: Steve on September 02, 2013, 11:14:49 AM
Quote from: roadfro on September 01, 2013, 03:42:29 AM
Tradephoric was saying that a quick glance at the signal head might cause one to inadvertently assume a flashing yellow was becoming steady. I assert that if you make a quick glance and note that the yellow arrow has jumped sections, then that's when you'd need to worry--if the yellow is still in the same section as where it was flashing before, there's no need to worry. It's a lot more noticeable that a light has changed sections than it is to switch from flashing to steady in the same signal section. This is why I prefer the 4-section FYA to the 3-section variant.
Agreed, and that's why the MUTCD shows a separate section for the FYA from the SYA in its signal diagrams.
The Macomb County FYA's are all the 4-section FYA variety yet still have seen a large increase in injury accidents. A 30% increase in injury accidents at FYA installs is concerning. At some point the theory goes out the window and the focus should on where the rubber meets the road. I would love to see before/after safety studies at FYA installs throughout the country to see if the increase in injury accidents at FYAs are more than just a regional phenomenon.
Quote from: tradephoric on September 09, 2013, 08:43:53 AM
Quote from: Steve on September 02, 2013, 11:14:49 AM
Quote from: roadfro on September 01, 2013, 03:42:29 AM
Tradephoric was saying that a quick glance at the signal head might cause one to inadvertently assume a flashing yellow was becoming steady. I assert that if you make a quick glance and note that the yellow arrow has jumped sections, then that's when you'd need to worry--if the yellow is still in the same section as where it was flashing before, there's no need to worry. It's a lot more noticeable that a light has changed sections than it is to switch from flashing to steady in the same signal section. This is why I prefer the 4-section FYA to the 3-section variant.
Agreed, and that's why the MUTCD shows a separate section for the FYA from the SYA in its signal diagrams.
The Macomb County FYA's are all the 4-section FYA variety yet still have seen a large increase in injury accidents. A 30% increase in injury accidents at FYA installs is concerning. At some point the theory goes out the window and the focus should on where the rubber meets the road. I would love to see before/after safety studies at FYA installs throughout the country to see if the increase in injury accidents at FYAs are more than just a regional phenomenon.
I hate them, myself. To me, the only application that makes sense is Dallas phasing (lead arrow one direction, lag arrow the other), and even then, states have had success with a flashing red arrow instead. (Hey, Delaware.) Red's safer than yellow.
Oddly enough, as I recall from the FYA testing, it was found that the FYA had better "signal recognition" from drivers than the traditional 5-lens (whether doghouse or vertical).
Quote from: Steve on September 09, 2013, 09:39:42 PM
I hate them, myself. To me, the only application that makes sense is Dallas phasing (lead arrow one direction, lag arrow the other), and even then, states have had success with a flashing red arrow instead. (Hey, Delaware.) Red's safer than yellow.
This is what Delaware drivers are taught to do at a flashing red arrow, taken directly from the Delaware Driver Manual:
Quote
Flashing red Arrow: Turns are permitted in the direction of a flashing red arrow after coming to a full stop. The full stop enables drivers to select a safe gap in the main flow of traffic, and then complete the turn without waiting for a green signal. Signal may be followed by a steady red arrow, steady yellow arrow or solid red ball.
While this may be what is taught, i doubt it is practiced by Delaware drivers. I imagine very few drivers will actually come to a complete stop at a flashing red arrow when there is safe gap in traffic. Michigan has the same type setup as Delaware (just with a flashing red ball as opposed to a flashing red arrow). This is what Michigan drivers are taught to do at a flashing red light:
QuoteA flashing red light means come to a full stop. Proceed when the road is clear.
In Michigan, drivers do not come to a complete stop when making a permissive left turn at a flashing red ball (assuming there is a safe gap in traffic). It's just a rule that isn't followed. I would say 99% of drivers in Michigan do not come to a complete stop, and that's a conservative estimate. If a driver does come to a complete stop, they are liable to get honked at and/or rear ended by the vehicle behind them.
Quote from: tradephoric on September 10, 2013, 09:44:49 PM
Quote from: Steve on September 09, 2013, 09:39:42 PM
I hate them, myself. To me, the only application that makes sense is Dallas phasing (lead arrow one direction, lag arrow the other), and even then, states have had success with a flashing red arrow instead. (Hey, Delaware.) Red's safer than yellow.
This is what Delaware drivers are taught to do at a flashing red arrow, taken directly from the Delaware Driver Manual:
Quote
Flashing red Arrow: Turns are permitted in the direction of a flashing red arrow after coming to a full stop. The full stop enables drivers to select a safe gap in the main flow of traffic, and then complete the turn without waiting for a green signal. Signal may be followed by a steady red arrow, steady yellow arrow or solid red ball.
While this may be what is taught, i doubt it is practiced by Delaware drivers. I imagine very few drivers will actually come to a complete stop at a flashing red arrow when there is safe gap in traffic. Michigan has the same type setup as Delaware (just with a flashing red ball as opposed to a flashing red arrow)...
You are pretty much correct. And if they are stopping, they are doing so well beyond the stop line, waiting for a gap in traffic.
Having said that, at least in the New Castle County area, a lot of the flashing left arrows have been eliminated, and now are simply protected left turns.
They also have a few oddball ones, like this example on Rt. 4 in Newark: It's basically a u-turn lane. WB Rt. 4 doesn't have a light whatsoever. The u-turn has a flashing red arrow, and EB Rt. 4 has a regular traffic light. By zooming out of the street view & looking around, the light's only reasonable purpose is to help serve traffic exiting a residential street that must turn right onto Rt. 4 WB before u-turning onto Rt. 4 EB. Even then, traffic would come to a regular, signalized intersection if they simply went over one block within that community.
Quote from: Mark68 on September 06, 2013, 05:02:41 AM
Colorado was mostly doghouse (probably as an add-on to the old 12-8-8 signals hanging from overhead wires in places such as Denver), then had some 4-sections and mostly 5-sections that were side-mounted (or center-mounted in the medians). Denver had some interesting ones with the normal 8-8-8 three section signals with two 12-inch signals added to the bottom for the green and yellow turn arrows. Now Aurora is installing the FYA (usually with four sections, some with three), Denver has installed their first two FYAs, and I have not heard of any other ones...yet...in other cities.
CDOT District 2 (Pueblo/Colorado Springs) uses them extensively. More so than the rest of the state put together.
Quote from: tradephoric on September 09, 2013, 08:43:53 AM
The Macomb County FYA's are all the 4-section FYA variety yet still have seen a large increase in injury accidents. A 30% increase in injury accidents at FYA installs is concerning. At some point the theory goes out the window and the focus should on where the rubber meets the road. I would love to see before/after safety studies at FYA installs throughout the country to see if the increase in injury accidents at FYAs are more than just a regional phenomenon.
You have to look at the type of accidents in totality though. A straight 30% increase in accidents doesn't tell you anything if you don't know the particulars of the accident. Is that increase directly attributable to the new FYA, or are there other factors that come into play? If there's an accompanying change of signal phasing with the FYA installation, that could be a factor. What's the duration of the accident increase--over a year, over three years, over three months? Three years of accident data is typically considered the minimum data period for a statistically significant traffic safety study/comparison. Is the increase in minor injury accidents offset by a reduction in serious injury accidents?
I seem to recall that some of the early adopters of FYAs (possibly somewhere in Oregon) had some before/after studies that showed reduction in accidents after FYAs went in. Don't quote me on that though...
Quote from: Steve on September 09, 2013, 09:39:42 PM
I hate them, myself. To me, the only application that makes sense is Dallas phasing (lead arrow one direction, lag arrow the other), and even then, states have had success with a flashing red arrow instead. (Hey, Delaware.) Red's safer than yellow.
Flashing red requires the full stop though, whereas flashing yellow doesn't. In replacing a circular green, using a flashing red doesn't achieve the same purpose and decreases throughput with the full stop (assuming vehicles actually come to a full stop). That said, FHWA did adopt some provision to use flashing red arrows in the last MUTCD, but that was more meant for permissive turns with safety things that would need a full stop (i.e. sight distance issues).
^^ However, the flashing red for a left turn is never treated as a complete stop unless opposing traffic is has not cleared. See Tradephroic's discussion of Michigan above (which I am very familiar with).
Quote from: Brandon on September 13, 2013, 07:20:27 AM
^^ However, the flashing red for a left turn is never treated as a complete stop unless opposing traffic is has not cleared. See Tradephroic's discussion of Michigan above (which I am very familiar with).
Then how would that differ from a flashing yellow arrow? Notwithstanding what Michigan did in the past with its flashing solid red indications, any present-day installations of flashing red arrows are intended to require turning traffic to come to a full stop, for the reasons cited by roadfro above.
Flashing red means come to a full stop before proceeding. Same as if the intersection was in flash mode, or a stop sign with a flashing red beacon above it.
Quote from: Brandon on September 13, 2013, 07:20:27 AM
^^ However, the flashing red for a left turn is never treated as a complete stop unless opposing traffic is has not cleared. See Tradephroic's discussion of Michigan above (which I am very familiar with).
Still, I think a flashing red is a little clearer than a flashing yellow in terms of what you're supposed to do. Flashing yellow generally means "it's the weekend, stop if it's red and then go, ignore if it's yellow," and you'd better not treat a FYA in that manner.
Quote from: Brandon on September 13, 2013, 07:20:27 AM
^^ However, the flashing red for a left turn is never treated as a complete stop unless opposing traffic is has not cleared. See Tradephroic's discussion of Michigan above (which I am very familiar with).
What you're describing is really no different than what the FYA is now.
The flashing red arrow introduced in the 2009 MUTCD (same time as the FYA in the national manual) has the same intent as the FYA, except that there is some engineering reason that decides that the driver making the permitted left turn MUST come to a full stop before turning. This "FRA" was also introduced with the optional supplementary R10-27 sign that reads "LEFT TURN YIELD ON FLASHING RED ARROW AFTER STOP".
In the early 1970s, the city of Toledo, OH rapidly went around and replaced all the traffic signals in town. The primary specs were:
- Mast arms (a handful of span wires remained, and top-bottom wires for longer spans)
- 12-inch only (they kept a lone 8-inch faced the the wrong way on one-way streets)
- Tunnel visors only
- Yellow-red flash mode after hours at minor intersections.
- 3M lenses for occasional left-turn signals, and at least one location where only the red section was 3M. At least one diagonal intersection (Monroe-Sylvania) was ALL 3M.
- And a LOT of 5-section "towers" for left-turns and right-turns, seemingly to the point of overkill. Protected-only left-turn-signals, like the occasional 3M, were rare. With at least one exception, the towers were Crouse-Hinds with the boxy backs; the upgrades were about a 50-50 split between that and Econolite Bullseyes.
This intersection was formed and signalized in 1981. http://goo.gl/maps/roJa8
This face is all towers: http://goo.gl/maps/r1Y19
And this intersection has a left-turn tower in each direction, except for SB which is a doghouse. At least by the '90s, it seems like they started warming up to doghouses.
Edit: forgot to include the link for that last one.
https://www.google.com/maps?ll=41.646749,-83.564072&spn=0.375589,0.529404&cbp=12,279.75,,1,-0.21&layer=c&panoid=g6mYfkynY46tZUaiapq-vw&cbll=41.67762,-83.604973&t=h&z=11
For what it's worth, note that if you look 180° behind, you'll see a scraped up RXR on the pavement, followed by a paved-over grade crossing. When these tracks were active, the signal flashed red in all directions when a train approached, along with the now-removed crossing lights. The tracks were ripped up in 2010.
Quote from: The High Plains Traveler on September 11, 2013, 03:57:17 PM
Quote from: Mark68 on September 06, 2013, 05:02:41 AM
Colorado was mostly doghouse (probably as an add-on to the old 12-8-8 signals hanging from overhead wires in places such as Denver), then had some 4-sections and mostly 5-sections that were side-mounted (or center-mounted in the medians). Denver had some interesting ones with the normal 8-8-8 three section signals with two 12-inch signals added to the bottom for the green and yellow turn arrows. Now Aurora is installing the FYA (usually with four sections, some with three), Denver has installed their first two FYAs, and I have not heard of any other ones...yet...in other cities.
CDOT District 2 (Pueblo/Colorado Springs) uses them extensively. More so than the rest of the state put together.
Seems like they're popping up everywhere in Aurora. Have seen a lot of replacement installations with the FYA. Saw one a couple weeks ago in downtown Denver at Speer Blvd & Chopper Circle (entrance to Pepsi Center), with a 4-section FYA.
Quote from: Steve on September 02, 2013, 11:14:49 AM
Quote from: roadfro on September 01, 2013, 03:42:29 AM
Tradephoric was saying that a quick glance at the signal head might cause one to inadvertently assume a flashing yellow was becoming steady. I assert that if you make a quick glance and note that the yellow arrow has jumped sections, then that's when you'd need to worry--if the yellow is still in the same section as where it was flashing before, there's no need to worry. It's a lot more noticeable that a light has changed sections than it is to switch from flashing to steady in the same signal section. This is why I prefer the 4-section FYA to the 3-section variant.
Agreed, and that's why the MUTCD shows a separate section for the FYA from the SYA in its signal diagrams.
I agree with Tradephoric. In my experience, the vast majority of protective/permissive signals have a lead-lead phasing. The way that a person would typically turn during the permissive phase is to wait for a gap in left turning traffic, or if there is no gap, turn during the end of yellow or all-red phase. Basically, the signals "train" us to think that both sides will have their green terminate at the same time.
There is a perceived yellow trap, because this type of turn is so ingrained in the driving public. I don't believe there is any way to train drivers out of that mindset safely, unless the thru signal lights were somehow blocked from the turning driver's view.
I grew up in California. I don't believe California allows for the FYA, because of the perceived yellow trap, as Tradephoric describes.
I've seen the following configurations in California that they consider safe:
Protective lead (RED ARROW or "Left turn on arrow only")
Protective lag (only after both thru directions get red)
Protective lead- Protective lead
Protective lead- Protective lag
Protective lag- Protective lag (only after both thru directions get red)
Protective/Permissive lead (Dog House on mast arm, 5 section signals on the side)
Protective/Permissive lead-Protective/Permissive lead
Protective/Permissive lag-Protective/Permissive lag (only after both thru directions get red)
Prohibited lead (NO LEFT OR U TURN) - Protective/Permissive lag (4 section signals)*
Prohibited lead - Protective lag
Protective lead (red arrow) - Protective/Permissive lag (4 section signal)
Where I currently live in Maryland, most of the protective/permissive signals are doghouses. There is a flashing red arrow nearby, but it seems to employ a lead phasing every time I see it, so there is no yellow trap potential. But I do worry that they may change it to allow a lagging left turn, which will lead to a perceived yellow trap.
* This arrangement is common at T-intersections or where a 2-way intersects with a one-way. This is an ideal signal arrangement, in my opinion, since it follows the standard approach of allowing lefts at any time there's a gap, and if there is no gap in traffic, turn when opposing traffic gets a red at the end of the cycle. For this to really work, the opposing left/u turn must be absolutely prohibited. An example is at First and Main in Downtown L.A.
How about signals that appear protective/permissive but are protective phase only?
CDOT (Chicago DOT) does this rather often. In direct violation of the MUTCD, I might add.
Lake Shore Drive:
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fi837.photobucket.com%2Falbums%2Fzz298%2Fmidamcrossrds%2F100_3677_zpsb968d57a.jpg&hash=cfc2576ea7ebc21dcd713b0ef8833c14ef6fa444) (http://s837.photobucket.com/user/midamcrossrds/media/100_3677_zpsb968d57a.jpg.html)
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fi837.photobucket.com%2Falbums%2Fzz298%2Fmidamcrossrds%2F100_3676_zps001a14d2.jpg&hash=c6c55fbef7d5dfb3d03fa00d6758f1474021b9ed) (http://s837.photobucket.com/user/midamcrossrds/media/100_3676_zps001a14d2.jpg.html)
Michigan Avenue:
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fi837.photobucket.com%2Falbums%2Fzz298%2Fmidamcrossrds%2F100_3678_zps5fa10fa0.jpg&hash=3bfbae77e7ba577998028491cde1c55f6495ed58) (http://s837.photobucket.com/user/midamcrossrds/media/100_3678_zps5fa10fa0.jpg.html)
I've mentioned before that Chicago DOTs deliberate and blatant disregard for national standards here pisses me off.
I was amazed/entertained/disgusted back in July when in Chicago I saw a CTA bus driver leaning on their horn and yelling (as if anyone could hear her outside the bus) at a car in front of her in the left turn lane who was obeying the sign at a green circular light on Michigan Ave. Bad enough for CDOT to flaunt national standards so badly, but then for CTA bus drivers to act like that? Sigh.
It seems like there ought to be enough room even on the narrow islands pictured here to have side-by-side 3-section signals for left turn and thru movements if they insist on protected turns; one could be red and the other green.
I have to give it to the MDC (or DCR or whoever is in charge of their roads now)....they may have some wacky nonstandard signals out there but they obey standards like green circles meaning permissive left.
(https://scontent-b-ord.xx.fbcdn.net/hphotos-frc3/s720x720/575058_10101527689010908_1465304880_n.jpg)
Considering I don't see many 5-section towers, I tend to marvel at them whenever I come across one. I remember Fayetteville, NC had an intersection that had a couple 5-section towers, but never crossed the intersection from where they faced.
I like how California, Illinois and other states install a 5-section tower on the left (or center) of an intersection along with a tower or doghouse on the mast arm, or wire. Same goes with 3-section left turn signals.
Also, I'd like to see more states install at least one signal (which applies) on the near-side of the intersection. This is what South Carolina is starting to do, hanging a single light from the wire at busy, rural intersections.
Quote from: PColumbus73 on November 04, 2013, 01:15:08 PM
Also, I'd like to see more states install at least one signal (which applies) on the near-side of the intersection. This is what South Carolina is starting to do, hanging a single light from the wire at busy, rural intersections.
Wisconsin always does this, and Illinois does it to a lesser extent in urban areas.
I like how Wisconsin arranges its traffic lights, it looks like would improve visability. Since I've heard that Wisconsin is slowly converting to all vertical signals, when they do, I wonder if they will use the doghouse or the 5-section tower
Quote from: PColumbus73 on November 04, 2013, 05:42:24 PM
I like how Wisconsin arranges its traffic lights, it looks like would improve visability. Since I've heard that Wisconsin is slowly converting to all vertical signals, when they do, I wonder if they will use the doghouse or the 5-section tower
Currently using the tower or FYA on new vertical installations. Word is they might allow the doghouse in the future.
Quote from: Big John on November 04, 2013, 05:45:58 PM
Quote from: PColumbus73 on November 04, 2013, 05:42:24 PM
I like how Wisconsin arranges its traffic lights, it looks like would improve visability. Since I've heard that Wisconsin is slowly converting to all vertical signals, when they do, I wonder if they will use the doghouse or the 5-section tower
Currently using the tower or FYA on new vertical installations. Word is they might allow the doghouse in the future.
New WisDOT installations are indeed going vertical, however, I have yet to see a new WisDOT installation with a 5-section tower. All the WisDOT stuff is either FYA or protected. Yes, I have heard from good authority that doghouses are in the toolbox, but I think it will be a
long time before they ever appear as part of a WisDOT installation. A) the FYA option has made it all but obsolete, B) it would require a whole new stream of parts to stock, and C) there's very little fresh blood in the signaling sections of the regional offices (read: a lot of old-school, it ain't broke don't change it, types).
Municipalities are a bigger question mark. West Bend hasn't touched the FYA and is still installing 5-section signals both vertically and horizontally. The reconstruction of Monona Dr from the beltline to the Madison city limits features 5-section towers mounted to monotubes.
How about a Flashing Yellow Arrow Doghouse.
New Minnesota standard for option lanes. Dedicated left turn lanes have a 4 head unless it's obvious the intersection can never, ever by protected/permissive, like if the left turn movements cross each other, in which case a 3 head is used.
^^ I don't think that is MUTCD compliant, in the use of a doghouse nor a bimodal lens for a FYA.
That is not confusing at all.
Nexus 5
Quote from: Mdcastle on November 09, 2013, 06:21:24 PM
How about a Flashing Yellow Arrow Doghouse.
<video>
New Minnesota standard for option lanes. Dedicated left turn lanes have a 4 head unless it's obvious the intersection can never, ever by protected/permissive, like if the left turn movements cross each other, in which case a 3 head is used.
Quote from: Big John on November 09, 2013, 07:21:45 PM
^^ I don't think that is MUTCD compliant, in the use of a doghouse nor a bimodal lens for a FYA.
The functional operation of this doghouse FYA would seem to be appropriate, and the bimodal lens is fine (it is the functional equivalent of the 3-section FYA with bimodal arrow). However, the use of this signal for option lanes is the problem. Turn arrows aren't supposed to be used for a shared lane unless operating in a protected mode.
Also, I've never seen a doghouse pole mounted on a side pole like this before...
Minnesota has lots of 4-lane roads that have a protected / permissive in one direction and permissive only in the other direction, with no dedicated left turn lanes. Sometimes but not always at diamond intersections. The first doghouse in the state has the same indications but runs a bit differently, it switches between split phase during peak times to permissive only off-peak. If this setup isn't common elsewhere it may explain why it wasn't though of while developing FYA,s and why Mn/DOT and FHWA had to discuss things to come up with a solution. Implementing a doghouse was a bit of trouble in Minnesota because they never had an official way to attach one to permanent poles, and they're rare enough that they probably have to be special ordered rather than pulled from local distributors stock.
Here's the original FYA doghouse, as noted above it works differently than the video of the brand new one at 90th Street. Minnesota practice is to repeat whatever face is the leftmost on the overhead on the post to the left, so the post on this one is a 4 section, not a doghouse.
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Ffarm4.staticflickr.com%2F3692%2F9062154467_ddf514c81b.jpg&hash=fc4e20df93f4121924b66377036ced98ab7157ab) (http://www.flickr.com/photos/26956281@N02/9062154467/)
IMG_2834 (http://www.flickr.com/photos/26956281@N02/9062154467/) by North Star Highways (http://www.flickr.com/people/26956281@N02/), on Flickr
That side-mounted FYA doghouse...gathering from your latest post that it's somewhere on 90th St in Bloomington, yes?
Quote from: Big John on November 09, 2013, 07:21:45 PM
^^ I don't think that is MUTCD compliant, in the use of a doghouse nor a bimodal lens for a FYA.
It appears FHWA may have ruled in favor of it:
http://mutcd.fhwa.dot.gov/reqdetails.asp?id=834 (http://mutcd.fhwa.dot.gov/reqdetails.asp?id=834)
Quote from: froggie on November 11, 2013, 07:12:00 AM
That side-mounted FYA doghouse...gathering from your latest post that it's somewhere on 90th St in Bloomington, yes?
Yes, 90th and I-35W ramps.
(I posted the same video on a traffic signals forum and a traffic signals Facebook group, so I'm having a hard time keeping track of what information I've shared where.)
Quote from: roadfro on November 10, 2013, 07:30:56 PM
Also, I've never seen a doghouse pole mounted on a side pole like this before...
Here is an example (https://www.google.com/maps/preview#!data=!1m8!1m3!1d3!2d-86.688642!3d34.713467!2m2!1f270.88!2f90.6!4f75!2m7!1e1!2m2!1sewQFCiZlwO4jAmWckltavg!2e0!5m2!1sewQFCiZlwO4jAmWckltavg!2e0!4m2!13m1!1e5&fid=5) of one in Huntsville, AL along Old Madison Pike at the entrance to Defense Acquisition University. This IMO would be a great candidate for a FYA.
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FRkfxjxG.png&hash=750e215046db936ede02678d8f4a37dd626cd7d8)
QuoteAlso, I've never seen a doghouse pole mounted on a side pole like this before...
There's a smattering here and there. I've seen examples in New Jersey (don't remember where offhand). And those who attended the Burlington, VT meet this past weekend would've seen one on US 7 in Burlington.
Quote from: codyg1985 on November 12, 2013, 06:47:23 AM
Quote from: roadfro on November 10, 2013, 07:30:56 PM
Also, I've never seen a doghouse pole mounted on a side pole like this before...
Here is an example (https://www.google.com/maps/preview#!data=!1m8!1m3!1d3!2d-86.688642!3d34.713467!2m2!1f270.88!2f90.6!4f75!2m7!1e1!2m2!1sewQFCiZlwO4jAmWckltavg!2e0!5m2!1sewQFCiZlwO4jAmWckltavg!2e0!4m2!13m1!1e5&fid=5) of one in Huntsville, AL along Old Madison Pike at the entrance to Defense Acquisition University. This IMO would be a great candidate for a FYA.
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FRkfxjxG.png&hash=750e215046db936ede02678d8f4a37dd626cd7d8)
That is a center pole mount, which I have seen done with a doghouse before. (Although usually, in my experience, a center pole mount doghouse is on a short pole with the doghouse signal being the only thing on the pole.) The one in the video appeared to be on the far left side pole of the intersection, which is unusual to me--such signals on the far left side are usually 5-section vertical towers. Installations like the one in this picture, with median mast poles, are also usually 5-section vertical towers...at least they are in Nevada.
Yes, this picture does depict a perfect candidate for a FYA display.
Quote from: PurdueBill on November 03, 2013, 09:29:40 PM
I was amazed/entertained/disgusted back in July when in Chicago I saw a CTA bus driver leaning on their horn and yelling (as if anyone could hear her outside the bus) at a car in front of her in the left turn lane who was obeying the sign at a green circular light on Michigan Ave. Bad enough for CDOT to flaunt national standards so badly, but then for CTA bus drivers to act like that? Sigh.
It seems like there ought to be enough room even on the narrow islands pictured here to have side-by-side 3-section signals for left turn and thru movements if they insist on protected turns; one could be red and the other green.
I have to give it to the MDC (or DCR or whoever is in charge of their roads now)....they may have some wacky nonstandard signals out there but they obey standards like green circles meaning permissive left.
(https://scontent-b-ord.xx.fbcdn.net/hphotos-frc3/s720x720/575058_10101527689010908_1465304880_n.jpg)
As part of the 2009 "merger - er - reorganization", MassDOT assumed full control of the Turnpike and the Metropolitan Highway System (i.e. Big Dig roadways and Boston Harbor tunnels, but only maintenance responsibility for many of the DCR roads like Storrow Drive. Design and construction responsibilities on the MDC/DCR parkways still lie with DCR.
QuoteAlso, I've never seen a doghouse pole mounted on a side pole like this before...
Peabody, Mass has at least a couple on Lowell Street (http://goo.gl/maps/yjr15) although at least one was recently changed to a 4-tall stack with a bimodal bottom arrow (kinda fancy for Peabody which usually does its own wacky things with sings and signals it seems)...as is common in that neck of the woods, there are a lot of intersections with no overhead signals, usually installations that came before the mid-to-late 80s.
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Ffarm6.staticflickr.com%2F5537%2F10913534685_78d10ef57c.jpg&hash=7e9b25b3f2313f3c8dcd488b04c5bb641f5bffcf) (http://www.flickr.com/photos/26956281@N02/10913534685/)
IMG_4384 (http://www.flickr.com/photos/26956281@N02/10913534685/) by North Star Highways (http://www.flickr.com/people/26956281@N02/), on Flickr
Here's a view of the whole mast. There's also one mounted on the end of the overhead mast over the lane.
Quote from: DaBigE on November 04, 2013, 06:37:02 PM
New WisDOT installations are indeed going vertical, however, I have yet to see a new WisDOT installation with a 5-section tower. All the WisDOT stuff is either FYA or protected. Yes, I have heard from good authority that doghouses are in the toolbox, but I think it will be a long time before they ever appear as part of a WisDOT installation. A) the FYA option has made it all but obsolete, B) it would require a whole new stream of parts to stock, and C) there's very little fresh blood in the signaling sections of the regional offices (read: a lot of old-school, it ain't broke don't change it, types).
Went through a construction area today in Appleton/Menasha (? - Mike) at Appleton Rd and Valley Rd. New monotubes are up, they are extra-thick so they look like WisDOT mast arms. on the Mainline (Appleton Rd - STH 47) there is a FYA setup for NB traffic, but for Valley Rd, there is a 5-section tower for the EB traffic on the mast arm and far side left pole-mounted signals.
New WisDOT installations are indeed going vertical, however, I have yet to see a new WisDOT installation with a 5-section tower. All the WisDOT stuff is either FYA or protected. Yes, I have heard from good authority that doghouses are in the toolbox, but I think it will be a long time before they ever appear as part of a WisDOT installation. A) the FYA option has made it all but obsolete, B) it would require a whole new stream of parts to stock, and C) there's very little fresh blood in the signaling sections of the regional offices (read: a lot of old-school, it ain't broke don't change it, types).
Municipalities are a bigger question mark. West Bend hasn't touched the FYA and is still installing 5-section signals both vertically and horizontally. The reconstruction of Monona Dr from the beltline to the Madison city limits features 5-section towers mounted to monotubes.
[/quote]
Eau Claire Wisconsin has a 2 intersections that I know of that were the first intersections in Eau Claire to be the new vertical monotube standard, and have some 5 stacks.
https://www.google.com/maps/place/Starr+Ave+%26+Birch+St,+Eau+Claire,+WI+54703/@44.820498,-91.478492,3a,75y,254.79h,87.71t/data=!3m7!1e1!3m5!1sWPkki3OWAVQX81bHHNBwQA!2e0!6s%2F%2Fgeo1.ggpht.com%2Fcbk%3Fpanoid%3DWPkki3OWAVQX81bHHNBwQA%26output%3Dthumbnail%26cb_client%3Dmaps_sv.tactile.gps%26thumb%3D2%26w%3D100%26h%3D80%26yaw%3D192.49835%26pitch%3D0!7i13312!8i6656!4m2!3m1!1s0x87f8bce0e7d36ccd:0x762385559649d5c0
https://www.google.com/maps/@44.826412,-91.476122,3a,75y,284.56h,85.07t/data=!3m7!1e1!3m5!1sK3005LlrzpVItV6lUiaiTQ!2e0!5s20110901T000000!7i13312!8i6656
Since this thread was bumped, I'll note that 4-section bimodals are dominant in Buffalo and on county-maintained highways in Erie County, NY. Region 5 has quite a few bimodals, but those are being phased out when installations are replaced. In one case (US 20 at Lake Avenue, Lancaster), a doghouse was replaced with a 4-section bimodal when the opposing left turn got a 4-section for PPLT operation. Doghouses are typically only found on county-maintained roads if they were installed by NYSDOT.
In certain states like Virginia there are 5 section tower signals, there are also some in NJ and New York.
In PA there are 5 section towers in Philadelphia, elsewhere in PA there are doghouses which have been around for a long time, the earliest being 12-inch Eagle flatbacks from the mid-1970s.
Quote from: PColumbus73 on November 04, 2013, 01:15:08 PM
I like how California, Illinois and other states install a 5-section tower on the left (or center) of an intersection along with a tower or doghouse on the mast arm, or wire. Same goes with 3-section left turn signals.
This. Would love to see a minimum of two signals for left turns applied in more states. I've only seen this in the upper midwest, southwest and western states.
There are some installations in Arizona (ADOT and the city of Scottsdale) that were installing 4-section signals (red ball, yellow ball, green ball, and bimodal arrow) before the FYA became more common.
Quote from: Signal on August 20, 2013, 12:37:07 PM
Quote from: dfnva on August 19, 2013, 10:06:22 PM
The most obvious VA exception I forgot about. Did Charlottesville use doghouses for their installs before the signals with bimodal arrows were installed? The earliest I recall considering the signals of Charlottesville was around 1999, marveling at the rare use (for VA) of the bimodal arrows. I could've sworn I saw a doghouse somewhere (not the 3M) but it may have been in Albemarle County.
Only within city limits are there bimodal arrows.
Inside Charlottesville, there are no 5-section signals (besides the 3M). Only 4-sections with bimodal arrows.
Outside Charlottesville, there are no 4-section w/ bimodal arrows. Only doghouses.
The closest doghouse signals in Charlottesville are at JPJ, outside of city limits.
Quote
The first time I saw one was in Bethesda, MD in the mid-1990s... is that about when bimodal arrows started being installed?
I honestly know little about bimodal arrow 'history'.
Before LEDs were used for signals, there were fiber-optic bimodal arrows.
Right now, all bimodal arrows in Charlottesville are LED except for 1 fiber-optic arrow (and it is currently not functioning).
In Charlottesville, there are two versions of LED bimodal arrows.
This arrow has clear glass, so you can see how it works. This video shows it changing close up and from a distance, then shows them in slow motion. You can see how there are alternatingly-colored LED lights in rows to form the arrow, so it noticably shifts a little when changing color.
This is the other version, with a frosted front. This has a more incandescent look, and you can't see any shift.
Here is a picture of the last fiber-optic bimodal arrow.
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Ffarm4.staticflickr.com%2F3671%2F9302863941_b6ab76f823_z.jpg&hash=d50e8d5602f7be1b0576f649541d30bd4a7d5f08) (http://www.flickr.com/photos/94611454@N02/9302863941/)
Fiber Optic Bimodal Arrow (http://www.flickr.com/photos/94611454@N02/9302863941/) by Signals Unlimited (http://www.flickr.com/people/94611454@N02/), on Flickr
Quote from: 1995hoo on August 20, 2013, 09:45:51 AM
Using Emmet Street at Ivy Road as an example: (1) Northbound Emmet gets a green ball to go straight and a green left arrow, southbound Emmet has a red. (2) The green arrow turns off and southbound Emmet gets a green ball but no turn arrow (so both directions are going straight). (3) Northbound Emmet's light turns completely red and southbound Emmet gets the green left-turn arrow along with the green ball.
That intersection no longer does that. There are two ways it cycles.
[1] If there is someone waiting to turn left NB on Emmet, but noone waiting SB on Emmet (it cycles vice versa too):
- NB Emmet gets green left arrow & thru signals. EB Ivy gets green right arrow.
- NB Emmet & EB Ivy's arrows go away. Both directions on Emmet St now have green thru signals and permissive left turn.
[2] If there is someone waiting to turn left in both directions on Emmet:
- NB & SB Emmet have green left arrows; red thru signals. EB & WB Ivy have green right arrows; red thru signals.
- SB Emmet's left arrow goes away. WB Ivy's right arrow goes away.
NB Emmet now has green arrow & thru signals. (EB Ivy still has green right). SB Emmet has all red. - NB Emmet & EB Ivy's arrows go away. Both directions on Emmet St now have green thru signals and permissive left turn. Both directions on Ivy have all red.
Another interesting bimodal use in Charlottesville is redundant, in a 3-section signal. It cycles like any protected turn signal, but the yellow arrow & yellow ball always come on at the same time.
That particular signal is now gone. There are only 2 remaining in that configuration.
In my town, there is a light with the arrow and yellow ball coming on at the same time. Here's the intersection link: https://www.google.com/maps/@42.4190754,-71.1561568,3a,15y,264.16h,93.74t/data=!3m7!1e1!3m5!1sK2DD6hfxVMS3O8l4MMsG6w!2e0!5s20121001T000000!7i13312!8i6656 , I'll take a photo. The link is a bit far away but it's showing that cycle.
Quote from: swbrotha100 on September 05, 2015, 09:44:53 AM
Quote from: PColumbus73 on November 04, 2013, 01:15:08 PM
I like how California, Illinois and other states install a 5-section tower on the left (or center) of an intersection along with a tower or doghouse on the mast arm, or wire. Same goes with 3-section left turn signals.
This. Would love to see a minimum of two signals for left turns applied in more states. I've only seen this in the upper midwest, southwest and western states.
I agree with both of you immensely. I find it totally unacceptable that some states permit the existence of one signal with arrows for a particular approach. What if something happens to one of the signal heads having arrows? There's nothing to back it up. It's especially egregious when you consider the number of intersections where a turning movement is more common than a movement straight through. I'm looking at you, pretty much every state in the Eastern Time Zone.