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Author Topic: Traffic signal  (Read 795643 times)

jakeroot

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Re: Traffic signal
« Reply #4650 on: August 03, 2022, 05:40:28 PM »

I saw this weird one in person in San Francisco last week walking back to my uncle's place just up the street. This is Vermont St at 16th St. When the light changes off the red, the bottom 2 lights flash yellow arrows. Vermont St becomes a one way street south of 16th heading north.

https://www.google.com/maps/@37.7661193,-122.4046944,3a,19.7y,175.32h,94.07t/data=!3m6!1e1!3m4!1s6atbRrC8knASjKzRRARyKw!2e0!7i16384!8i8192

This is incredibly strange. But I love it!
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mrsman

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Re: Traffic signal
« Reply #4651 on: August 03, 2022, 07:56:56 PM »

I saw this weird one in person in San Francisco last week walking back to my uncle's place just up the street. This is Vermont St at 16th St. When the light changes off the red, the bottom 2 lights flash yellow arrows. Vermont St becomes a one way street south of 16th heading north.

https://www.google.com/maps/@37.7661193,-122.4046944,3a,19.7y,175.32h,94.07t/data=!3m6!1e1!3m4!1s6atbRrC8knASjKzRRARyKw!2e0!7i16384!8i8192

This is incredibly strange. But I love it!

Many weird signals in SF.  They have  some unique interpretations of traffic engineering.

Given the high density of pedestrians, they definitely try some novel things.

OK, this intersection is at a point where two-traffic becomes one-way traffic in the opposite direction.  The one-way portion of Vermont is northbound.  If you are north of the intersection on the two-way portion facing southbound, you must turn either left or right.  Going straight is not an option.

In most other places, this will be signified with a green ball.  Green ball means right of way going forward (but that movement is prohibited), yielding to oncoming traffic and pedestrians going left, and yielding to pedestrians going right.  I guess there is a concern that traffic seeing the green ball will just go straight and blow through the do not enter, so they came up with alternative signals to handle the yielding turn movements.  Both left FYA and right FYA have meanings consistent with the turn must yield, so they are good choices, although somewhat unorthodox. 

Here is a GSV of the same intersection going back to 2009.

https://www.google.com/maps/@37.7661399,-122.4046398,3a,37.5y,168.09h,92.32t/data=!3m7!1e1!3m5!1snvWMmAdugA2wUP0YS2JCHw!2e0!5s20090701T000000!7i13312!8i6656

The bottom aspect is a flashing yellow ball to warn of the danger of forcing turns (which is why a green ball wasn't used).  I imagine that since the flashing yellow ball doesn't really have any official meaning other than caution, and is most often used to denote an intersection where cross traffic faces a flashing red ball, it was changed to the arrows that we see today.

It may have been less confusing if there were four separate signal faces, instead of three.  Then, you could have two signal faces controlling the left movement and two signal faces controlling the right movement.  But that would add to the expense when there were already three signal faces present.
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jakeroot

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Re: Traffic signal
« Reply #4652 on: August 03, 2022, 09:27:28 PM »

Here is a GSV of the same intersection going back to 2009.

https://www.google.com/maps/@37.7661399,-122.4046398,3a,37.5y,168.09h,92.32t/data=!3m7!1e1!3m5!1snvWMmAdugA2wUP0YS2JCHw!2e0!5s20090701T000000!7i13312!8i6656

The bottom aspect is a flashing yellow ball to warn of the danger of forcing turns (which is why a green ball wasn't used).  I imagine that since the flashing yellow ball doesn't really have any official meaning other than caution, and is most often used to denote an intersection where cross traffic faces a flashing red ball, it was changed to the arrows that we see today.

Reminds me of this intersection in Seattle:

East Marginal Way S / 1st Ave S: https://goo.gl/maps/KD2zwUJvXVXzX6te6

The left turn from 1st Ave S to East Marginal Way S is a quadruple left turn, but there is also a driveway leaving from the opposite industrial park. Though perhaps in the past it may have been green orbs in all directions (technically denoting a four-lane yield?), the driveway approach uses a flashing yellow orb. Sadly I cannot find this on street view, though you can see the yellow orbs in this GSV image (may need to pan up). In practice, vehicles leaving from the driveway correctly yield, although sometimes, as many of the vehicles are large trucks, they just command the right-of-way, forcing left turning traffic to yield.
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mrsman

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Re: Traffic signal
« Reply #4653 on: August 04, 2022, 07:41:59 AM »

Here is a GSV of the same intersection going back to 2009.

https://www.google.com/maps/@37.7661399,-122.4046398,3a,37.5y,168.09h,92.32t/data=!3m7!1e1!3m5!1snvWMmAdugA2wUP0YS2JCHw!2e0!5s20090701T000000!7i13312!8i6656

The bottom aspect is a flashing yellow ball to warn of the danger of forcing turns (which is why a green ball wasn't used).  I imagine that since the flashing yellow ball doesn't really have any official meaning other than caution, and is most often used to denote an intersection where cross traffic faces a flashing red ball, it was changed to the arrows that we see today.

Reminds me of this intersection in Seattle:

East Marginal Way S / 1st Ave S: https://goo.gl/maps/KD2zwUJvXVXzX6te6

The left turn from 1st Ave S to East Marginal Way S is a quadruple left turn, but there is also a driveway leaving from the opposite industrial park. Though perhaps in the past it may have been green orbs in all directions (technically denoting a four-lane yield?), the driveway approach uses a flashing yellow orb. Sadly I cannot find this on street view, though you can see the yellow orbs in this GSV image (may need to pan up). In practice, vehicles leaving from the driveway correctly yield, although sometimes, as many of the vehicles are large trucks, they just command the right-of-way, forcing left turning traffic to yield.

The intersection is unique enough that it is probably justified for the industrial park to have their own exclusive phase to enter that is separate from the phases for both 1st Ave and Marginal Way.

Los Angeles has a practice that many driveways at signalized intersections will see a flashing red light in place of green.  30 years ago, this meant a signal face with two aspects that the top light was solid red (concurrent with opposing red and yellow) and bottom light was flashing red (concurrent with opposing green). 

Here's one that still exists at La Tijera/Knowlton:

https://www.google.com/maps/@33.976085,-118.3731878,3a,75y,141.96h,79.18t/data=!3m6!1e1!3m4!1sLu5JwGwAvUMFsqJxLsh9Bw!2e0!7i16384!8i8192

Modern versions of this signal have incorporated a yellow signal in the bottom aspect - so red, flashing red, yellow. 

Here's an example at a bank parking lot at Pico/Livonia.  Middle light is illuminated and it's a flashing red, pan around to see that Livonia traffic sees a green light during the same time.  Traffic exiting the bank parking lot sees a sign to "watch opposing traffic."

https://www.google.com/maps/@34.0551659,-118.3863613,3a,37.5y,243.56h,87.59t/data=!3m6!1e1!3m4!1sazM-jxKu7tboUrfxdCAQow!2e0!7i13312!8i6656

[Personally, I don't like this approach either.  Busy driveways should just get their own green, either as an exclusive phase in a split-phase timing pattern, or as a regular green where left turners from either direction have to yield to opposing traffic.  I'm not sure that you can convince drivers coming out of the private driveway, who only get a brief period when main street traffic gets a red, to stop and yield to all opposing traffic, even when heading straight.  Especially, that in many cases the private driveway could be busier than the side street, like at the shopping center off La Tijera.]

More San Francisco weirdness.  Here is the corner of Franklin and Oak.  Oak is a primary eastbound street that gets a lot of traffic.  [It borders the Panhandle park, where it gets a lot of traffic funnelling onto it from the west and the Panhandle was the route of a cancelled freeway.]  All of that traffic is forced to make a left turn onto northbound Franklin, a triple left.  Yet, there is one orphaned block of Oak that exists to the east.  Since Oak ends right at the intersection of Van Ness/Market, one of the busiest intersections in the city, that one block is one-way westbound, away from Market.  This one westbound block does not get much traffic, but it will face off with all of the Oak traffic turning left on Franklin.  So, the westbound traffic sees a one aspect red signal.  This signal flashes red when opposing Oak gets their green left arrow, and is solid red otherwise.

https://www.google.com/maps/@37.7752697,-122.4205912,3a,15y,267.33h,88.79t/data=!3m7!1e1!3m5!1sLt5vI05xOdVvz9wWq8CVQQ!2e0!6shttps:%2F%2Fstreetviewpixels-pa.googleapis.com%2Fv1%2Fthumbnail%3Fpanoid%3DLt5vI05xOdVvz9wWq8CVQQ%26cb_client%3Dmaps_sv.tactile.gps%26w%3D203%26h%3D100%26yaw%3D15.486733%26pitch%3D0%26thumbfov%3D100!7i16384!8i8192

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steviep24

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Re: Traffic signal
« Reply #4655 on: August 04, 2022, 03:14:52 PM »

^^
I've never seen a u-turn arrow in New York. NYSDOT just uses regular left turn arrows for u-turn signals.
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BuildTheRussian

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Re: Traffic signal
« Reply #4656 on: August 05, 2022, 10:22:43 AM »

^^
I've never seen a u-turn arrow in New York. NYSDOT just uses regular left turn arrows for u-turn signals.
In some jurisdictions, you may only proceed in the arrow's direction, meaning that it would be illegal for anyone to make a U-turn there. That is the case in countries like Poland and the UK.
« Last Edit: August 05, 2022, 10:43:56 AM by BuildTheRussian »
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roadfro

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Re: Traffic signal
« Reply #4657 on: August 10, 2022, 12:27:25 PM »

Here is a GSV of the same intersection going back to 2009.

https://www.google.com/maps/@37.7661399,-122.4046398,3a,37.5y,168.09h,92.32t/data=!3m7!1e1!3m5!1snvWMmAdugA2wUP0YS2JCHw!2e0!5s20090701T000000!7i13312!8i6656

The bottom aspect is a flashing yellow ball to warn of the danger of forcing turns (which is why a green ball wasn't used).  I imagine that since the flashing yellow ball doesn't really have any official meaning other than caution, and is most often used to denote an intersection where cross traffic faces a flashing red ball, it was changed to the arrows that we see today.

It may have been less confusing if there were four separate signal faces, instead of three.  Then, you could have two signal faces controlling the left movement and two signal faces controlling the right movement.  But that would add to the expense when there were already three signal faces present.

There appears to be only one lane on this approach, so having separate signal faces for the left and right turns would probably be a bit unnecessary.

Also intriguing is that there's a fire station on the corner here, and the approach we've been discussing is right at the station's garages. So vehicles are supposed to stop probably a good 40 or 50 feet back from the intersection. I'm surprised there's not a supplemental signal anywhere back there, because the main signals are quite distant.
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Lukeisroads

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jakeroot

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Re: Traffic signal
« Reply #4660 on: August 11, 2022, 12:39:34 PM »

^^^
I recall Oregon using this style of mounting with some regularity as well.
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jeffandnicole

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Re: Traffic signal
« Reply #4662 on: August 11, 2022, 10:41:41 PM »

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Amtrakprod

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Re: Traffic signal
« Reply #4663 on: August 12, 2022, 03:15:55 PM »

^^^
I recall Oregon using this style of mounting with some regularity as well.
Yup


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US71

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Re: Traffic signal
« Reply #4664 on: August 12, 2022, 03:56:10 PM »

^^^
I recall Oregon using this style of mounting with some regularity as well.
Yup



Is the little guy a ped signal?
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mrsman

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Re: Traffic signal
« Reply #4665 on: August 12, 2022, 06:39:21 PM »

^^^
I recall Oregon using this style of mounting with some regularity as well.
Yup



It's also a bike signal.  Very European style to use near-side small signals for bikes.  This must be either 3" or 4" diameter lights on the signal face.
Is the little guy a ped signal?
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roadman65

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Re: Traffic signal
« Reply #4666 on: August 12, 2022, 11:24:39 PM »

Found a two section signal head still in use in Brooklyn, NY.
https://goo.gl/maps/3HF5vyCes9vZMEqM6

The funny thing is itís only for one direction. The others have the normal three section heads.
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jeffandnicole

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Re: Traffic signal
« Reply #4667 on: August 12, 2022, 11:57:53 PM »

Found a two section signal head still in use in Brooklyn, NY.
https://goo.gl/maps/3HF5vyCes9vZMEqM6

The funny thing is itís only for one direction. The others have the normal three section heads.

It's a 2 head red blinker, although looking at a series of GSVs coming down the street, it may be a steady red at top for a time period, then alternating red on top & bottom. https://goo.gl/maps/sYuQfvFNar5Mb3L89 then https://goo.gl/maps/JeNHQbBdefvYkvnt9
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RestrictOnTheHanger

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Re: Traffic signal
« Reply #4668 on: August 13, 2022, 09:25:40 AM »

Found a two section signal head still in use in Brooklyn, NY.
https://goo.gl/maps/3HF5vyCes9vZMEqM6

The funny thing is itís only for one direction. The others have the normal three section heads.

It's a 2 head red blinker, although looking at a series of GSVs coming down the street, it may be a steady red at top for a time period, then alternating red on top & bottom. https://goo.gl/maps/sYuQfvFNar5Mb3L89 then https://goo.gl/maps/JeNHQbBdefvYkvnt9

Those 2 section red lights are usually solid red on top, then change to flashing red on the bottom. Usually used for a driveway or other special circumstance.
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roadman65

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Re: Traffic signal
« Reply #4669 on: August 13, 2022, 09:27:20 AM »

https://goo.gl/maps/MrXzh9CC1zFheUKG8

This one is a rarity https://goo.gl/maps/MrXzh9CC1zFheUKG8

A 12-8-12.  Usually 8-8-12 are common in New York for protected left heads or exclusive turns at an intersection.  This one, however, is to encourage no left turns and to also let motorists know that the street crossing is one way from the right.  You would think to use all 12 inch lenses here instead of this.
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jakeroot

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Re: Traffic signal
« Reply #4670 on: August 13, 2022, 11:52:22 AM »

^^^
There are some 12-8-12 signals in Tacoma, WA. The city went and retrofitted all red signals to be 12 inches 10-20 years ago. Those signals that already had 12-inch green arrows became 12-8-12.

https://goo.gl/maps/zaPAZkxgRo9PK4Wj7
https://goo.gl/maps/wHcs1Qzk9ec43wZC9
https://goo.gl/maps/3nLnhAx2rtYVQ6cV6
https://goo.gl/maps/gTmtoe25UWVuUnKw6

There is also a bunch of 12-8-8-12-12 towers across the city, but that's for another time and place.
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steviep24

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Re: Traffic signal
« Reply #4671 on: August 13, 2022, 01:32:10 PM »

8 8 8 12 12 signal towers mounted on mast arms. These are on NY 31 at Elmwood Ave. in Rochester, NY. These are the only signals of that configuration left in the Rochester, NY area.

https://www.google.com/maps/@43.1262815,-77.5643684,3a,37.5y,298.03h,89.54t/data=!3m6!1e1!3m4!1sAmwhuCbHGXN3_ME9WUUiXA!2e0!7i16384!8i8192?hl=en&authuser=0

8 8 8 12 12 towers are common in NYC but are never mounted on the mast arm.
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roadman65

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Re: Traffic signal
« Reply #4672 on: August 13, 2022, 10:20:20 PM »

8 8 8 12 12 signal towers mounted on mast arms. These are on NY 31 at Elmwood Ave. in Rochester, NY. These are the only signals of that configuration left in the Rochester, NY area.

https://www.google.com/maps/@43.1262815,-77.5643684,3a,37.5y,298.03h,89.54t/data=!3m6!1e1!3m4!1sAmwhuCbHGXN3_ME9WUUiXA!2e0!7i16384!8i8192?hl=en&authuser=0

8 8 8 12 12 towers are common in NYC but are never mounted on the mast arm.

Iíve seen NYC use 12-12 and 8-8-8 side by side when that application is used on mast arms.
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steviep24

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Re: Traffic signal
« Reply #4673 on: August 14, 2022, 06:30:27 PM »

This is interesting.

https://www.google.com/maps/@43.1131502,-77.5505011,3a,75y,152.84h,100.72t/data=!3m6!1e1!3m4!1sMHxLzy53niePTY8McpEV9w!2e0!7i16384!8i8192?hl=en&authuser=0

This was recently installed on NY 31 (Monroe Ave.) in Pittsford, NY. The mast arm for EB traffic has only a left turn FYA signal. No other signals are on the mast arm.
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SignBridge

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Re: Traffic signal
« Reply #4674 on: August 14, 2022, 08:19:50 PM »

That's very puzzling.
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