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Author Topic: Traffic signal  (Read 760699 times)

kphoger

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Re: Traffic signal
« Reply #4525 on: May 17, 2022, 02:29:04 PM »


Here’s an interesting light I stumbled upon:

What the duck?

I'm not a signal guy, so correct me if I'm wrong, but...  doesn't this work functionally the same as a standard RYG light with right-turn arrows?
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Re: Traffic signal
« Reply #4526 on: May 17, 2022, 05:25:59 PM »

Here’s an interesting light I stumbled upon:

iPhone

What a ridiculous setup. That bottom arrow on the 4-section is completely unnecessary. It just needs to be a standard left turn signal.
It’s even weirder bc the left lane is a shared left and right turn lane


iPhone
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Re: Traffic signal
« Reply #4527 on: May 17, 2022, 05:40:04 PM »

For the record, I don’t believe California has any rules about signal-per-lane. That is a recommendation within the MUTCD, but California has historically had quite a unique set of rules for signal placement and operation. Distinct enough that I doubt they even recognize the MUTCD’s recommendation. Not that they really need to, I prefer California’s strategy ten-fold.

I think Alaska is the same about the signal per lane discussion, they have a table in their own state MUTCD that gives a certain number of overhead signals on an approach that's not one overhead signal per lane, and requires a far right supplemental signal to be mounted.
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jakeroot

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Re: Traffic signal
« Reply #4528 on: May 17, 2022, 08:19:26 PM »

For the record, I don’t believe California has any rules about signal-per-lane. That is a recommendation within the MUTCD, but California has historically had quite a unique set of rules for signal placement and operation. Distinct enough that I doubt they even recognize the MUTCD’s recommendation. Not that they really need to, I prefer California’s strategy ten-fold.

I think Alaska is the same about the signal per lane discussion, they have a table in their own state MUTCD that gives a certain number of overhead signals on an approach that's not one overhead signal per lane, and requires a far right supplemental signal to be mounted.

Very true. For example, I don't think I've seen a double left turn in Alaska that has more than one overhead left turn signal. Every double left turn has a single overhead left turn signal, and a far-left corner left turn signal.

Alaska actually has some of the best signals in the US, and it rarely seems to get much recognition. I know supplemental left corner signals are required for all approaches that don't use fully-permissive phasing, and far-right supplemental signals are mandatory.
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roadman65

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Re: Traffic signal
« Reply #4529 on: May 17, 2022, 08:38:50 PM »

https://goo.gl/maps/Hvdok6admkGeDKzBA

What kind of signal is that red x on the two section for?
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Sheryl Crowe

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Re: Traffic signal
« Reply #4530 on: May 17, 2022, 09:00:45 PM »

https://goo.gl/maps/Hvdok6admkGeDKzBA

What kind of signal is that red x on the two section for?

If I had to ask, maybe a MUNI (bus) queue jump to go straight (or even left)?
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roadman65

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Re: Traffic signal
« Reply #4531 on: May 17, 2022, 11:33:39 PM »

https://goo.gl/maps/Hvdok6admkGeDKzBA

What kind of signal is that red x on the two section for?

If I had to ask, maybe a MUNI (bus) queue jump to go straight (or even left)?

I’m not from there.  In Florida we use white PRR positional signals in a three section head for buses.
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Sheryl Crowe

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Re: Traffic signal
« Reply #4532 on: May 18, 2022, 08:15:41 PM »

Roadman65, I assume you're referring to traditional Pennsylvania Railroad position-light signals, in the form of white rectangular bars in the signal heads?

Didn't know you were a railroad buff! LOL
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Big John

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Re: Traffic signal
« Reply #4533 on: May 18, 2022, 11:17:18 PM »

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kphoger

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Re: Traffic signal
« Reply #4534 on: May 19, 2022, 09:37:01 AM »



https://goo.gl/maps/Hvdok6admkGeDKzBA

What kind of signal is that red x on the two section for?

If I had to ask, maybe a MUNI (bus) queue jump to go straight (or even left)?

I’m not from there.  In Florida we use white PRR positional signals in a three section head for buses.

See below.

Quote from: San Francisco Municipal Transportation Agency
Upgrading the T: Weigh in on a New Type of Train Signal on 3rd Street
Rachel Hyden, 22–FEB-2017

Implementing a Standard, Concise Design for Train Signals


Currently, Muni trains are guided by three different types of train signals. We’re in the process of upgrading 400 signals along the T Line to one uniform system within the next few months.


The three designs used for existing train signals (left) which will be consolidated into one standard type of signal (right).
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Re: Traffic signal
« Reply #4535 on: May 22, 2022, 05:45:01 PM »

Stumbled across these signals in Cancun when looking at Street View - RGB LED matrix panels instead of separate lights. https://www.google.com/maps/@21.1742923,-86.8268313,3a,82.6y,244.25h,96.39t/data=!3m7!1e1!3m5!1s3WYGeifU8LYMch94MzsPdg!2e0!5s20161201T000000!7i13312!8i6656
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Dirt Roads

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Re: Traffic signal
« Reply #4536 on: May 22, 2022, 08:55:00 PM »

https://goo.gl/maps/Hvdok6admkGeDKzBA

What kind of signal is that red x on the two section for?

If I had to ask, maybe a MUNI (bus) queue jump to go straight (or even left)?

I’m not from there.  In Florida we use white PRR positional signals in a three section head for buses.

See below.

Quote from: San Francisco Municipal Transportation Agency
Upgrading the T: Weigh in on a New Type of Train Signal on 3rd Street
Rachel Hyden, 22–FEB-2017

Implementing a Standard, Concise Design for Train Signals


Currently, Muni trains are guided by three different types of train signals. We’re in the process of upgrading 400 signals along the T Line to one uniform system within the next few months.


The three designs used for existing train signals (left) which will be consolidated into one standard type of signal (right).

Oh, that's interesting.  I like this concept, but the red "lowered semaphore" is specifically not recommended by MUTCD because the red lens can be illuminated by sunshine and therefore be misinterpreted by automotive traffic.  That being said, I'm pretty sure that it is not specifically discouraged because a misinterpreted red traffic signal is not inherently unsafe (even though there are some safety issues related to the next car seeing a green signal).  I doubt that there are any situations where a red (or lunar white) "lowered semaphore" transit signal is displayed for a route where automotive traffic is given a green phase.

Fun fact:  What Roadman65 affectionately calls "PRR positional signals" is an attempt by certain railroads to duplicate the position of a magnetically-activated semaphore blade with an attached multiple-lens searchlight signal head.  The Baltimore and Ohio had color position light (CPL) signals and the Pennsylvania Railroad (along with the Norfolk and Western and others) had position light signals.  The top-and-bottom positions are for a clear aspect (no obstruction ahead in the next two blocks, a situation where the semaphore blade is standing straight up (to simulate a signalman with a lantern held up).  The 45-degree diagonal positions are for an approach aspect (approach next signal prepared to stop).  The left-and-right positions are for a stop aspect, a situation where the semaphore blade has a lowered arm (to simulate a signalman with a lantern held out).  The B&O had green-yellow-red lenses in these positions, respectively; whereas the PRR simply used lunar white lenses all the way around. 

By the way, there is another position (the minus-45-degree semaphore blade) which is a "call-on signal" where the dispatcher has specifically granted the train permission to pass a stop signal.  Those are always lunar white, no matter which railroad and what type of signal.  (Don't get this confused with what other railroads used as lower-quadrant semaphores).
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plain

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Re: Traffic signal
« Reply #4537 on: May 22, 2022, 08:58:00 PM »

Stumbled across these signals in Cancun when looking at Street View - RGB LED matrix panels instead of separate lights. https://www.google.com/maps/@21.1742923,-86.8268313,3a,82.6y,244.25h,96.39t/data=!3m7!1e1!3m5!1s3WYGeifU8LYMch94MzsPdg!2e0!5s20161201T000000!7i13312!8i6656

Yeah various parts of Mexico have been using those for quite a while now.
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SignBridge

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Re: Traffic signal
« Reply #4538 on: May 22, 2022, 10:05:44 PM »

Dirt Roads, Pennsy used yellow in their position-light signals. White was only used in dwarf signals.
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kphoger

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Re: Traffic signal
« Reply #4539 on: May 23, 2022, 03:02:04 PM »


Stumbled across these signals in Cancun when looking at Street View - RGB LED matrix panels instead of separate lights. https://www.google.com/maps/@21.1742923,-86.8268313,3a,82.6y,244.25h,96.39t/data=!3m7!1e1!3m5!1s3WYGeifU8LYMch94MzsPdg!2e0!5s20161201T000000!7i13312!8i6656

Yeah various parts of Mexico have been using those for quite a while now.

As I mentioned at some point on some thread:  what wasn't immediately obvious to me when I first started seeing them in Mexico is that they only have one aspect per signal.  I guess you'd better hope the affected colorblind drivers know how to read!
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Re: Traffic signal
« Reply #4540 on: May 23, 2022, 04:49:48 PM »


Stumbled across these signals in Cancun when looking at Street View - RGB LED matrix panels instead of separate lights. https://www.google.com/maps/@21.1742923,-86.8268313,3a,82.6y,244.25h,96.39t/data=!3m7!1e1!3m5!1s3WYGeifU8LYMch94MzsPdg!2e0!5s20161201T000000!7i13312!8i6656

Yeah various parts of Mexico have been using those for quite a while now.

As I mentioned at some point on some thread:  what wasn't immediately obvious to me when I first started seeing them in Mexico is that they only have one aspect per signal.  I guess you'd better hope the affected colorblind drivers know how to read!

To be fair, the red ALTO light is on top and the green SIGA light is on the bottom... and any rate, looking at newer imagery, it looks like the dot-matrix part is still there but they dispensed with the words and now it just looks like a regular traffic light.

Hobart

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Re: Traffic signal
« Reply #4541 on: May 23, 2022, 06:37:45 PM »


Stumbled across these signals in Cancun when looking at Street View - RGB LED matrix panels instead of separate lights. https://www.google.com/maps/@21.1742923,-86.8268313,3a,82.6y,244.25h,96.39t/data=!3m7!1e1!3m5!1s3WYGeifU8LYMch94MzsPdg!2e0!5s20161201T000000!7i13312!8i6656

Yeah various parts of Mexico have been using those for quite a while now.

As I mentioned at some point on some thread:  what wasn't immediately obvious to me when I first started seeing them in Mexico is that they only have one aspect per signal.  I guess you'd better hope the affected colorblind drivers know how to read!

To be fair, the red ALTO light is on top and the green SIGA light is on the bottom... and any rate, looking at newer imagery, it looks like the dot-matrix part is still there but they dispensed with the words and now it just looks like a regular traffic light.

I'm frankly still not a huge fan of them. I feel like there's more to go wrong and that they're more difficult to service. They just... don't look right to me I guess.
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kphoger

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Re: Traffic signal
« Reply #4542 on: May 24, 2022, 10:04:06 AM »

To be fair, the red ALTO light is on top and the green SIGA light is on the bottom...

Cool, thanks for pointing that out.

I see the same is true at a horizontal signal I'm familiar with as well.

Red ball is on the left, green ball is on the right.
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Re: Traffic signal
« Reply #4543 on: May 26, 2022, 12:48:46 PM »

Quote from: San Francisco Municipal Transportation Agency
Upgrading the T: Weigh in on a New Type of Train Signal on 3rd Street
Rachel Hyden, 22–FEB-2017

Implementing a Standard, Concise Design for Train Signals


Currently, Muni trains are guided by three different types of train signals. We’re in the process of upgrading 400 signals along the T Line to one uniform system within the next few months.


The three designs used for existing train signals (left) which will be consolidated into one standard type of signal (right).

Very interesting that they decided to use red in the final design. The third pattern (with the two white bars) they're changing out is the only one of these that is MUTCD-compliant.
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SignBridge

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Re: Traffic signal
« Reply #4544 on: May 26, 2022, 07:54:15 PM »

Does Calif. have a State Supplement to the Federal Manual? If they do, does it maybe authorize the red stop bar to be used?
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kphoger

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Re: Traffic signal
« Reply #4547 on: May 27, 2022, 12:27:55 AM »

Wonder why you need three lights WHEN YOU CANT U TURN OR LEFT https://www.google.com/maps/@35.4412251,-119.0473766,3a,49.1y,270.57h,93.34t/data=!3m7!1e1!3m5!1syGZj6DA4vGSWkVhjn0qHTA!2e0!6shttps:%2F%2Fstreetviewpixels-pa.googleapis.com%2Fv1%2Fthumbnail%3Fpanoid%3DyGZj6DA4vGSWkVhjn0qHTA%26cb_client%3Dmaps_sv.tactile.gps%26w%3D203%26h%3D100%26yaw%3D196.8536%26pitch%3D0%26thumbfov%3D100!7i16384!8i8192

They could have had that many signals on the mast arm in case the cross street gets extended across and the leftmost signal needs to be changed out for a left turn one.

I do agree though, three thru signals overhead for one direction is a bit much. I know the MUTCD advises one overhead per lane, but two thru signals and the right supplemental thru signal should be perfectly fine, especially considering that's what they're doing on the oncoming approach.
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Re: Traffic signal
« Reply #4549 on: May 28, 2022, 12:20:45 AM »

To be fair, the red ALTO light is on top and the green SIGA light is on the bottom...

Cool, thanks for pointing that out.

I see the same is true at a horizontal signal I'm familiar with as well.

Red ball is on the left, green ball is on the right.

That one is...less great. With the red/green background, it could be kind of hard to tell which end is the ball if you're far enough away that you can't read the text.

I'm frankly still not a huge fan of them. I feel like there's more to go wrong and that they're more difficult to service. They just... don't look right to me I guess.

LED panels like that are cheap enough nowadays if anything went wrong you could probably replace the whole signal head and it wouldn't be too much more expensive than replacing a single aspect in a traditional signal.
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