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Traffic signal

Started by Tom89t, January 14, 2012, 01:01:45 AM

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Dirt Roads

Quote from: Dirt Roads on September 01, 2024, 02:00:23 PMI'm wondering if the alternating green/yellow flash is an experimental MMU malfunction flash mode that is intended to encourage traffic to continue over the crossing, but provide some level of warning that side traffic is in flash mode and might pull into the crossing after yielding.  If so, this green/yellow flash feature would only be needed on the side of the crossing with advance traffic signals (before the crossing), but most traffic signal controllers cannot be programmed in such a manner. 

Quote from: fwydriver405 on September 02, 2024, 10:24:34 AMWouldn't just flashing just circular yellow on the approaches from the railroad crossing or on both approaches (in this particular case, the main street) be less confusing and standardised on almost all controllers, since you said that the green and yellow flash can't be programmed in this manner, even on the newest ATC controllers?

The primary issue is that drivers running on a green ball understand that they are protected to operate over the crossing then through the intersection, but when the flashing yellow comes up, drivers are more likely to want to stop on the tracks to yield to cross-traffic that has been sitting for long times.

It's not that green/yellow flash cannot be programmed for only one direction of traffic; I'm sure that this can be done with a 16-phase traffic controller.  But RR crossing preemption is a standard function for most traffic controller, so many crossings are supplemented with much simpler (and less expensive) traffic controllers.


roadfro

Quote from: Ned Weasel on September 03, 2024, 08:02:01 PM
Quote from: plain on March 06, 2023, 05:05:04 PMThey were probably trying to emphasize that particular lane is thru only (based on the 5-section tower to the right of it for right turns).

WA seems to be the state with the most red up arrows still left around.

The MUTCD has banned red and yellow up arrows for a long time (Section 4F.01, Paragraph 09), but new ones are still popping up!

Brand new signal in Kansas City, MO (Main Street and MLK Boulevard): https://maps.app.goo.gl/h3yGGRzqtdmCXzeh8

Recent DDI in Manhattan, KS (KS 18 and KS 113): https://maps.app.goo.gl/iCaj2e63BKY4RSbN6

Also this DDI in New Mexico (I-25 and NM 14): https://maps.app.goo.gl/vgLemGQeSNY7mqAY6

Are exceptions being handed out left and right, and do engineers really believe that sometimes a red up arrow is better than a circular red in certain situations?  Or are some people just forgetting what's in the MUTCD?
Nevada agencies are usually good about following MUTCD. But the one consistent non-compliant thing I've seen in different parts of the state is the use of red & yellow up arrows for the arterial signals at DDI interchanges. 

I think up arrows should be allowed for the DDI use case and other limited applications where absolutely no turns would be allowed. That first example from Kansas City appears to have no reason to use the up arrows for those through movements.
Roadfro - AARoads Pacific Southwest moderator since 2010, Nevada roadgeek since 1983.

PColumbus73

There were a couple up-pointed FYA signals in North Carolina that were later fixed. Which makes me wonder if there might be a situation that might warrant such a signal.


https://www.google.com/maps/@34.3103599,-77.7781205,3a,30.5y,350.51h,91.62t/data=!3m7!1e1!3m5!1sBh_asV90tsvGzJxI3Oa8VA!2e0!5s20120901T000000!7i13312!8i6656?coh=205409&entry=ttu&g_ep=EgoyMDI0MDkwMy4wIKXMDSoASAFQAw%3D%3D

jakeroot

Quote from: Ned Weasel on September 03, 2024, 08:02:01 PMRecent DDI in Manhattan, KS (KS 18 and KS 113): https://maps.app.goo.gl/iCaj2e63BKY4RSbN6

Also this DDI in New Mexico (I-25 and NM 14): https://maps.app.goo.gl/vgLemGQeSNY7mqAY6

I know this is completely beside the point...but I'm surprised to see agencies building DDI's without any near-side signals. Back home in WA, a state not exactly known for supplemental signals (outside of specific agencies), the single DDI we built has near-side signals on all approaches, with the inside approaches each having two (either side of the limit-line).

See here on Google Street View: https://maps.app.goo.gl/gUhwQiMUyMS6TF297

jakeroot

Quote from: PColumbus73 on September 06, 2024, 12:57:37 PMThere were a couple up-pointed FYA signals in North Carolina that were later fixed. Which makes me wonder if there might be a situation that might warrant such a signal.


https://www.google.com/maps/@34.3103599,-77.7781205,3a,30.5y,350.51h,91.62t/data=!3m7!1e1!3m5!1sBh_asV90tsvGzJxI3Oa8VA!2e0!5s20120901T000000!7i13312!8i6656?coh=205409&entry=ttu&g_ep=EgoyMDI0MDkwMy4wIKXMDSoASAFQAw%3D%3D

I know it has been fixed, but that is very interesting! I've never seen an FYA signal used with an up arrow, they are always exactly 90-degrees. Even the "fix" with it being angled is very rare, maybe one-of-a-kind.

Of course, it's not really warranted. Putting the left turn signal near the guard-rail would be far enough off to the right to use a standard 90-degree left arrow. Mounting it overhead (on that ridiculously-long mast-arm) basically made it necessary to use the angled arrow, as it is kind-of straight-on from the limit line. The alternative would be to move the limit line back so that the median-mounted left turn signal is the primary signal, and then they wouldn't feel the need for the supplemental left turn signal to be placed so dead-center ahead of the left turn lane.

plain

#5380
Up arrows are useful in situations where an agency wants to emphasize no turns allowed at a particular intersection or from a particular lane. Why the feds frown upon red ones is beyond me, but it kinda feels like they want to ensure that arrows of any color are meant for turns.

I myself have absolutely no issues with them (even reds) being used at a DDI, as they emphasize that the only way you're supposed to proceed is straight.

Quote from: PColumbus73 on September 06, 2024, 12:57:37 PMThere were a couple up-pointed FYA signals in North Carolina that were later fixed. Which makes me wonder if there might be a situation that might warrant such a signal.



https://www.google.com/maps/@34.3103599,-77.7781205,3a,30.5y,350.51h,91.62t/data=!3m7!1e1!3m5!1sBh_asV90tsvGzJxI3Oa8VA!2e0!5s20120901T000000!7i13312!8i6656?coh=205409&entry=ttu&g_ep=EgoyMDI0MDkwMy4wIKXMDSoASAFQAw%3D%3D

This one is a doozy. I can almost see why they had the up arrow in the middle of turning, except it would imply that a U-turn is prohibited. What replaced the up arrows here?

EDIT: Nevermind, I see they replaced it with a slanted arrow.
Newark born, Richmond bred

thenetwork

#5381
Quote from: PColumbus73 on September 06, 2024, 12:57:37 PMThere were a couple up-pointed FYA signals in North Carolina that were later fixed. Which makes me wonder if there might be a situation that might warrant such a signal.


https://www.google.com/maps/@34.3103599,-77.7781205,3a,30.5y,350.51h,91.62t/data=!3m7!1e1!3m5!1sBh_asV90tsvGzJxI3Oa8VA!2e0!5s20120901T000000!7i13312!8i6656?coh=205409&entry=ttu&g_ep=EgoyMDI0MDkwMy4wIKXMDSoASAFQAw%3D%3D

Never noticed the red up arrows on the ramp from EB I-70 to CO-82 (Under I-70) in Glenwood Springs CO until I read the post yesterday -- then drove past.it the same day!

fwydriver405

Quote from: plain on September 06, 2024, 08:31:12 PMUp arrows are useful in situations where an agency wants to emphasize no turns allowed at a particular intersection or from a particular lane. Why the feds frown upon red ones is beyond me, but it kinda feels like they want to ensure that arrows of any color are meant for turns.

I myself have absolutely no issues with them (even reds) being used at a DDI, as they emphasize that the only way you're supposed to proceed is straight.

This signal (installed around late 2020) at Lake Street at Minuteman Bikeway in Arlington, MA, actually had all of its vehicular circular indications on Lake changed to thru arrows a few months after activation. This primarily was because too many drivers, especially those travelling east on Lake wanting to turn left at the Brooks Ave intersection ~60 m / ~200 ft east of this one, kept trying to turn onto the bikeway thinking that was Brooks Ave, despite the "NO TURNS" signage on Lake St and "NO MOTOR VEHICLES" sign on the bikeway divider. Yes, this has happened before in the past...

Elsewhere in Massachusetts, Cambridge seems to do this sometimes (Examples 1, 2) at intersections with signal separation, though they have started to use circular red and yellow now for the thru traffic at most new installations. And then you have questionable examples, such as this slip lane* in Milton, MA or this signal for the thru lane from the shopping plaza in Bangor, ME.

*Signal is an overlap for the Adams Street protected left.

roadfro

Quote from: jakeroot on September 06, 2024, 07:50:54 PM
Quote from: Ned Weasel on September 03, 2024, 08:02:01 PMRecent DDI in Manhattan, KS (KS 18 and KS 113): https://maps.app.goo.gl/iCaj2e63BKY4RSbN6

Also this DDI in New Mexico (I-25 and NM 14): https://maps.app.goo.gl/vgLemGQeSNY7mqAY6

I know this is completely beside the point...but I'm surprised to see agencies building DDI's without any near-side signals. Back home in WA, a state not exactly known for supplemental signals (outside of specific agencies), the single DDI we built has near-side signals on all approaches, with the inside approaches each having two (either side of the limit-line).

See here on Google Street View: https://maps.app.goo.gl/gUhwQiMUyMS6TF297
That looks like it could be because the overhead signals seem to be set a decent distance from the stop lines, which means they are less visible from upstream from where the curve to crossover happens (and thus might require a near-side signal face).
Roadfro - AARoads Pacific Southwest moderator since 2010, Nevada roadgeek since 1983.

jakeroot

Quote from: roadfro on September 08, 2024, 09:22:08 PM
Quote from: jakeroot on September 06, 2024, 07:50:54 PM
Quote from: Ned Weasel on September 03, 2024, 08:02:01 PMRecent DDI in Manhattan, KS (KS 18 and KS 113): https://maps.app.goo.gl/iCaj2e63BKY4RSbN6

Also this DDI in New Mexico (I-25 and NM 14): https://maps.app.goo.gl/vgLemGQeSNY7mqAY6

I know this is completely beside the point...but I'm surprised to see agencies building DDI's without any near-side signals. Back home in WA, a state not exactly known for supplemental signals (outside of specific agencies), the single DDI we built has near-side signals on all approaches, with the inside approaches each having two (either side of the limit-line).

See here on Google Street View: https://maps.app.goo.gl/gUhwQiMUyMS6TF297
That looks like it could be because the overhead signals seem to be set a decent distance from the stop lines, which means they are less visible from upstream from where the curve to crossover happens (and thus might require a near-side signal face).

True, there is a decent distance between the limit line and signals. But then even still, only one near-side signal would be required (likely far-left). Plus the opposite direction (the crossing back-over approach) also has dual near-side signals, yet the overhead signals are about 140 feet away (25 feet closer than the other approach).

This all said ... you're missing the point. DDIs usually have a significant, sometimes sharp curve in the road, where the signals might only be visible briefly before the limit line. Ideally, near-side signals should be provided to increase obedience with the signal and reduce red light running. And this is true for every [signalized] approach at a DDI, as almost all approaches are on a curve.

I surveyed the Horizon Drive DDI in Henderson, NV, and was dismayed that only some of the approaches have any supplemental signals; several have zero. This seems so strange to me, when Nevada DOT usually provides ample supplemental signals. WSDOT is not as good about using supplemental signals, yet every approach at the Lacey, WA DDI has at least one, and three approaches have two.

CJResotko

3-section FYAs are extremely rare in Michigan. There's only two places (that I'm currently aware of) that have them.

Birmingham - Maple and Eton

Jackson - Cooper and Michigan/Louis Glick (added recently!)
*insert something witty here*

roadman65

https://maps.app.goo.gl/xRAAQhfpBvdPH8fA6
Looks to me like this dark green was not manufactured as such, as the yellow is showing beneath the peeling.  A preexisting yellow head painted over later as originally all New York City ( except Fifth Avenue between 34th and 59th) used to be all yellow heads.

https://maps.app.goo.gl/ymYpnZ7gUGic4uk29
Then using a 8-8-12 paired long side of a 12-12-12. IMO both signal heads should be 12-12-12.

However, it seems like NY is one of the few places, still, using eight inch lenses. NJ where I grew up seems to be slowly phasing them out, and don't know how many eight inch heads are still left in PA, MD, and the Carolinas who used them very frequently at one time.
Every day is a winding road, you just got to get used to it.

Sheryl Crowe

freebrickproductions

Quote from: roadman65 on September 25, 2024, 03:29:52 PMHowever, it seems like NY is one of the few places, still, using eight inch lenses.

IIRC, NYC still uses 8 inch as standard, as most roads in the city have a speed limit of 30 MPH or below.

Quote from: roadman65 on September 25, 2024, 03:29:52 PMthe Carolinas

When I was in NC a couple months ago, there were still quite a few 8 inch lights, usually newer aluminum Mark IV heads with LEDs and the occasional McCain mixed in, also with LEDs, though I did spot a few older heads in service still. I think SC is mostly 12 inch these days, I ain't seen too many 8 inch heads there when I've visited that state, aside from the 8 inch lights on railroad crossings.
It's all fun & games until someone summons Cthulhu and brings about the end of the world.

I also collect traffic lights, road signs, fans, and railroad crossing equipment.

(They/Them)

PColumbus73

Quote from: freebrickproductions on September 25, 2024, 04:59:26 PM
Quote from: roadman65 on September 25, 2024, 03:29:52 PMHowever, it seems like NY is one of the few places, still, using eight inch lenses.

IIRC, NYC still uses 8 inch as standard, as most roads in the city have a speed limit of 30 MPH or below.

Quote from: roadman65 on September 25, 2024, 03:29:52 PMthe Carolinas

When I was in NC a couple months ago, there were still quite a few 8 inch lights, usually newer aluminum Mark IV heads with LEDs and the occasional McCain mixed in, also with LEDs, though I did spot a few older heads in service still. I think SC is mostly 12 inch these days, I ain't seen too many 8 inch heads there when I've visited that state, aside from the 8 inch lights on railroad crossings.

You'll find more 8" and 12-8-8s in the Charleston area, but generally they're all 12s elsewhere in SC

SignBridge

Quote from: roadman65 on September 25, 2024, 03:29:52 PMhttps://maps.app.goo.gl/xRAAQhfpBvdPH8fA6
Looks to me like this dark green was not manufactured as such, as the yellow is showing beneath the peeling.  A preexisting yellow head painted over later as originally all New York City ( except Fifth Avenue between 34th and 59th) used to be all yellow heads.

https://maps.app.goo.gl/ymYpnZ7gUGic4uk29
Then using a 8-8-12 paired long side of a 12-12-12. IMO both signal heads should be 12-12-12.

However, it seems like NY is one of the few places, still, using eight inch lenses. NJ where I grew up seems to be slowly phasing them out, and don't know how many eight inch heads are still left in PA, MD, and the Carolinas who used them very frequently at one time.

IMO NYC should have continued using yellow signal heads in Manhattan. They contrast much better with the generally dark urban background. No idea why they went to dark color heads.

Regrettably Nassau County NY DPW on Long Island still uses a mix of 8-inch and 12-inch heads. It's not unusual to see a new installation at an intersection of a main road and a side street where there are 12-inch heads facing the main road and 8-inch facing the side street. It looks ridiculous but that's what they do, apparently applying the MUTCD rules literally and trying to save a few bucks. They also still use all 8-inch at some intersections of two smaller streets.

freebrickproductions

Quote from: SignBridge on September 25, 2024, 08:15:05 PMIt looks ridiculous but that's what they do, apparently applying the MUTCD rules literally and trying to save a few bucks.

TBQH, I suspect why a lot of places even just use all 12 inch to begin with is because it makes maintenance/replacements easier.
It's all fun & games until someone summons Cthulhu and brings about the end of the world.

I also collect traffic lights, road signs, fans, and railroad crossing equipment.

(They/Them)

roadman65

I actually prefer the yellow heads in NYC.  Even when Fifth Avenue had battleship grey, it was okay as it was for aesthetics being that particular street is sort of like Midtown's Main Street.

Lots of cities have one such street with different signal heads to deviate it from the rest due to importance or other reasons.  Atlantic City, NJ uses horizontal mounts but on trombone brackets like most NJ horizontal mounts, but on Atlantic Avenue they use monotube arms with standard vertical mounts.

New York, lately, has been picking random intersections to paint dark colors and not consistent to a street or neighborhood, although one user on here believes NYC is only using green to denote upscale neighborhoods.

I still want to know why NYC has not gone to digital controllers as they still maintain the use of analog click boxes mounted to one of the signal poles and not a free standing cabinet like most of the US, including Washington, DC and Los Angeles.

Even on Staten Island they still use the small click boxes where the environment there is more suburban and Richmond Avenue is even an arterial that could really use computer signal timings.

One thing good I  will say about NYC is, unlike the rest of NY State that has one left turn signal head, in the city you will always see two heads like across the river in NJ or like AZ, CA, and IL.  In fact I think NYC copies New Jersey more than its own state hence the two main signals on two different mast arms.
Every day is a winding road, you just got to get used to it.

Sheryl Crowe

PColumbus73

Found an intersection where an FYA and a doghouse was used. It looks like the FYA was installed part of a commercial development, but they weren't required to upgrade the existing doghouse.

https://www.google.com/maps/@33.5434844,-80.8315981,3a,88.8y,270.22h,77.84t/data=!3m7!1e1!3m5!1sAjxUfmEF1wQbU6Ur-oYSMA!2e0!5s20230701T000000!7i16384!8i8192?coh=205409&entry=ttu&g_ep=EgoyMDI0MDkyMy4wIKXMDSoASAFQAw%3D%3D

hwyfan

Quote from: roadfro on September 06, 2024, 11:00:05 AM
Quote from: Ned Weasel on September 03, 2024, 08:02:01 PM
Quote from: plain on March 06, 2023, 05:05:04 PMThey were probably trying to emphasize that particular lane is thru only (based on the 5-section tower to the right of it for right turns).

WA seems to be the state with the most red up arrows still left around.

The MUTCD has banned red and yellow up arrows for a long time (Section 4F.01, Paragraph 09), but new ones are still popping up!

Brand new signal in Kansas City, MO (Main Street and MLK Boulevard): https://maps.app.goo.gl/h3yGGRzqtdmCXzeh8

Recent DDI in Manhattan, KS (KS 18 and KS 113): https://maps.app.goo.gl/iCaj2e63BKY4RSbN6

Also this DDI in New Mexico (I-25 and NM 14): https://maps.app.goo.gl/vgLemGQeSNY7mqAY6

Are exceptions being handed out left and right, and do engineers really believe that sometimes a red up arrow is better than a circular red in certain situations?  Or are some people just forgetting what's in the MUTCD?
Nevada agencies are usually good about following MUTCD. But the one consistent non-compliant thing I've seen in different parts of the state is the use of red & yellow up arrows for the arterial signals at DDI interchanges.

I think up arrows should be allowed for the DDI use case and other limited applications where absolutely no turns would be allowed. That first example from Kansas City appears to have no reason to use the up arrows for those through movements.


Straight-through red arrows in Las Vegas area:

1) South Grand Central Parkway at Iron Horse Court:  https://maps.app.goo.gl/yTEyYrkEtKiDzXG39

2) West Charleston Boulevard at Interstate 15 northbound ramps:  https://maps.app.goo.gl/CARrY9yhm5JAy74t8




roadman65



Here's one that was during a power outage in Palm Coast, Florida.   While taking this, it's by law to be treated as four way stop intersection. However, many do not do so.
Every day is a winding road, you just got to get used to it.

Sheryl Crowe

roadman65

Then this a new concept. Two section double green arrows.
https://www.flickr.com/photos/54480415@N08/54067183160
Every day is a winding road, you just got to get used to it.

Sheryl Crowe

jakeroot

Quote from: roadman65 on October 14, 2024, 03:06:24 PMWhile taking this, it's by law to be treated as four way stop intersection. However, many do not do so.

It's alarming to me how many don't realize the law (in most states, at least) requires stopping at a dark signal. Back in WA, I recall most drivers stopping, but I'm sure some places are worse than others.

Of course, HAWKs (even though they are "beacons") do nothing to remind people of that.

US 89

Quote from: jakeroot on October 14, 2024, 10:23:10 PM
Quote from: roadman65 on October 14, 2024, 03:06:24 PMWhile taking this, it's by law to be treated as four way stop intersection. However, many do not do so.

It's alarming to me how many don't realize the law (in most states, at least) requires stopping at a dark signal. Back in WA, I recall most drivers stopping, but I'm sure some places are worse than others.

There is definitely a lot of regional variability. Here in Utah, I find most people stop. When I lived in Tallahassee just about nobody did. Either it was "free green for the bigger road" or "go when you feel like you deserve it". I'm amazed there were not more accidents there given how the power there seemed to go out whenever a bird so much as sneezed on the wires.

jeffandnicole

Quote from: jakeroot on October 14, 2024, 10:23:10 PM
Quote from: roadman65 on October 14, 2024, 03:06:24 PMWhile taking this, it's by law to be treated as four way stop intersection. However, many do not do so.

It's alarming to me how many don't realize the law (in most states, at least) requires stopping at a dark signal. Back in WA, I recall most drivers stopping, but I'm sure some places are worse than others.

Of course, HAWKs (even though they are "beacons") do nothing to remind people of that.

A more common school of thought - albeit against the intention of the law - is that when one roadway is clearly the main roadway, they will get priority and keep moving, and the side street is expected to stop and proceed when safe.

In some cases I've seen around here where there has been an intersection out (and this works easier when there's some sort of median), police will place cones in the center of the intersection forcing the secondary road traffic to turn right, and the main road will intentionally keep moving thru the darkened signal.  Is it proper?  No.  Does it prevent a ridiculously large backup on the primary road, especially during rush hours?  Yes.

Revive 755

Quote from: roadman65 on October 14, 2024, 08:39:40 PMThen this a new concept. Two section double green arrows.
https://www.flickr.com/photos/54480415@N08/54067183160

Streetview has it as well.

It doesn't appear MUTCD compliant.

Quote from: 11th Edition MUTCD, 4E.03 Paragraphs 02 and 03Unless otherwise provided in this Manual for a particular application, each signal face at a signalized location shall have three, four, or five signal sections. Unless otherwise provided in this Manual for a particular application, if a vertical signal face includes a cluster (see Section 4E.04), the signal face shall have at least three vertical positions.

A single-section signal face shall be permitted at a traffic control signal if it consists of a continuously-displayed GREEN ARROW signal indication that is being used to indicate a continuous movement.



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