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Author Topic: Traffic signal  (Read 361836 times)

roadfro

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Re: Traffic signal
« Reply #2400 on: July 04, 2019, 02:19:36 PM »

Curious what people think of this: https://goo.gl/maps/8WQEYeisRgDNc79Y9

In the link, there's a couple things to notice:

1) the right turn (from the linked approach) is a slip lane
2) there are two left turn lanes at the signal (right lane may go straight)
3) the overhead signals have one green left arrow, one green orb, and one green right arrow (latter two stacked upon each other).

Based on the information, I think the right-green arrow may have been installed facing the wrong direction (right instead of left). There is no indication that right turns are even permitted at the intersection, plus (more importantly) this sort of setup, with two green left arrows and a green orb were very common prior to the 2009 MUTCD for option lane approaches without a dedicated right turn lane, at least in states that don't require pole-mounted signals (such as VA). The signal in the original link was installed in 2013/2014, although the signal may have been designed prior to VDOT's adoption of the 2009 MUTCD.

Given the right turn movement is separated by a pork chop island, and the crosswalk across that right turn doesn’t have a ped signal, a right turn arrow is not appropriate here. Also with the left turn being the apparent major movement, two left arrows are necessary. So I would agree with you that the right-facing arrow should probably be left-facing instead.
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mrsman

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Re: Traffic signal
« Reply #2401 on: July 04, 2019, 02:26:34 PM »

Curious what people think of this: https://goo.gl/maps/8WQEYeisRgDNc79Y9

In the link, there's a couple things to notice:

1) the right turn (from the linked approach) is a slip lane
2) there are two left turn lanes at the signal (right lane may go straight)
3) the overhead signals have one green left arrow, one green orb, and one green right arrow (latter two stacked upon each other).

Based on the information, I think the right-green arrow may have been installed facing the wrong direction (right instead of left). There is no indication that right turns are even permitted at the intersection, plus (more importantly) this sort of setup, with two green left arrows and a green orb were very common prior to the 2009 MUTCD for option lane approaches without a dedicated right turn lane, at least in states that don't require pole-mounted signals (such as VA). The signal in the original link was installed in 2013/2014, although the signal may have been designed prior to VDOT's adoption of the 2009 MUTCD.

I agree with your assessment that the right arrow should be a left arrow.  In fact, if it were a right arrow, it would be a violation since you aren't allowed to turn right from that lane (signal head does not face the slip lane).  Further, even if you were, it is unsafe since the right arrow is on at the same time when pedestrians are allowed to cross (notice the 12 seconds remaining on the flashing don't walk phase).  It is also not appropriate to give a signal to the slip lane, since the peds crossing the slip lane don't have a signal (and could legally cross at any time).

If the area gets more pedestrianized, which is a goal of a lot of Tysons planners, they would need to have a signal to control the crossing of the slip lane as well as the right turn itself.  The right turn should allow a green arrow for all times that the main signal is green and when Tysons one has a left green arrow onto Westpark.  There should be a no turn on red arrow when pedestrians are crossing the slip lane, and perhaps a permitted turn on red (maybe a flashing red arrow) at other times, like when Tysons One has green but no peds are crossing the slip lane.
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jakeroot

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Re: Traffic signal
« Reply #2402 on: July 05, 2019, 06:17:53 PM »

Given the right turn movement is separated by a pork chop island, and the crosswalk across that right turn doesn’t have a ped signal, a right turn arrow is not appropriate here. Also with the left turn being the apparent major movement, two left arrows are necessary. So I would agree with you that the right-facing arrow should probably be left-facing instead.

Definitely. I'm almost 100% certain it was placed in the wrong direction anyways...

I agree with your assessment that the right arrow should be a left arrow.  In fact, if it were a right arrow, it would be a violation since you aren't allowed to turn right from that lane (signal head does not face the slip lane).  Further, even if you were, it is unsafe since the right arrow is on at the same time when pedestrians are allowed to cross (notice the 12 seconds remaining on the flashing don't walk phase).  It is also not appropriate to give a signal to the slip lane, since the peds crossing the slip lane don't have a signal (and could legally cross at any time).

If the area gets more pedestrianized, which is a goal of a lot of Tysons planners, they would need to have a signal to control the crossing of the slip lane as well as the right turn itself.  The right turn should allow a green arrow for all times that the main signal is green and when Tysons one has a left green arrow onto Westpark.  There should be a no turn on red arrow when pedestrians are crossing the slip lane, and perhaps a permitted turn on red (maybe a flashing red arrow) at other times, like when Tysons One has green but no peds are crossing the slip lane.

(Bolded part) didn't see that before! With that in mind, we can almost be certain that the arrow was placed in the wrong direction. Plus, bi-modal right-turn overlap signals are very rare (unheard of?) in VA (99% are doghouses, if not all), so this sort of setup would be unlikely anyways.

I can see the intersection losing all but the north-to-north slip-lane in the near future, or yes, signalizing the crossing would be great too. Maybe even with a flashing yellow arrow? It could turn red when pedestrians hit the button. Or it could just be timed to flash red when the walk sign automatically activates. It's fine for now, but the way Tysons is growing, it'll be appropriate to pedestrianise it more in the future. Improving access across Chain Bridge and Leesburg Pike should be focused on too. Those are huge roads.
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CJResotko

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Re: Traffic signal
« Reply #2403 on: July 11, 2019, 11:02:23 AM »

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TEG24601

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Re: Traffic signal
« Reply #2404 on: July 11, 2019, 12:59:59 PM »

I couple of interesting, likely older installations near Bremerton, WA.


https://imgur.com/wGvp7yF
https://imgur.com/PmFKT4p


New installation at SR 525 and Alderwood Mall Parkway in Lynnwood, WA


https://imgur.com/jWtsxbx
https://imgur.com/jne7285
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mrsman

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Re: Traffic signal
« Reply #2405 on: July 11, 2019, 01:37:06 PM »

I couple of interesting, likely older installations near Bremerton, WA.


https://imgur.com/wGvp7yF
https://imgur.com/PmFKT4p




Very interesting, a 12-8-12 (bottom is a left green arrow) and a 12-8-8-8.  If you passed by this intersection, can you tell me how this looks when green?  An 8" signal phase head for an arrow is rare and I don't know what else would justify 4 signal phase heads.
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TEG24601

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Re: Traffic signal
« Reply #2406 on: July 11, 2019, 02:10:00 PM »

The left one was just a green arrow.  The right one had a green ball and a green arrow.
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plain

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Re: Traffic signal
« Reply #2407 on: July 11, 2019, 07:44:51 PM »

I couple of interesting, likely older installations near Bremerton, WA.


https://imgur.com/wGvp7yF
https://imgur.com/PmFKT4p


New installation at SR 525 and Alderwood Mall Parkway in Lynnwood, WA


https://imgur.com/jWtsxbx
https://imgur.com/jne7285

In that first example, I can't remember seeing completely round signal heads like that, and mixed with traditional ones at that. Wow.

In the example with that new install, what exactly is the lane configuration there? That's a very strange signal setup (the green orbs is throwing me off).
EDIT: Nevermind, just saw it on Google Maps. The green orb on the right signal is completely unnecessary.
« Last Edit: July 11, 2019, 07:53:03 PM by plain »
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jakeroot

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Re: Traffic signal
« Reply #2408 on: July 11, 2019, 08:35:23 PM »

EDIT: Nevermind, just saw it on Google Maps. The green orb on the right signal is completely unnecessary.

Two green orbs are required for every approach with a through lane, regardless of lane setup. This is Washington's lazy attempt to satisfy this rule.

I couple of interesting, likely older installations near Bremerton, WA.

https://imgur.com/wGvp7yF
https://imgur.com/PmFKT4p

An 8-inch green arrow. Sweet find! These are rare in WA.
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plain

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Re: Traffic signal
« Reply #2409 on: July 11, 2019, 09:26:33 PM »

EDIT: Nevermind, just saw it on Google Maps. The green orb on the right signal is completely unnecessary.

Two green orbs are required for every approach with a through lane, regardless of lane setup. This is Washington's lazy attempt to satisfy this rule.

It's safe to say VDOT and several other VA agencies habitually ignore this rule lmao
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traffic light guy

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Re: Traffic signal
« Reply #2410 on: July 12, 2019, 12:42:57 AM »

Those appear to be Econolte signals,nice find. 8-inch arrows are now an MUTCD violation

LG-M327

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jakeroot

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Re: Traffic signal
« Reply #2411 on: July 12, 2019, 04:03:42 AM »

EDIT: Nevermind, just saw it on Google Maps. The green orb on the right signal is completely unnecessary.

Two green orbs are required for every approach with a through lane, regardless of lane setup. This is Washington's lazy attempt to satisfy this rule.

It's safe to say VDOT and several other VA agencies habitually ignore this rule lmao

Depending on when VDOT adopted the 2009 MUTCD (the version that included this requirement), signals that didn't follow this rule may have been installed as late as 2013 or 2014 (or even later).
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TEG24601

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    • Tegianzone
Re: Traffic signal
« Reply #2412 on: July 12, 2019, 12:09:36 PM »

EDIT: Nevermind, just saw it on Google Maps. The green orb on the right signal is completely unnecessary.

Two green orbs are required for every approach with a through lane, regardless of lane setup. This is Washington's lazy attempt to satisfy this rule.

It's safe to say VDOT and several other VA agencies habitually ignore this rule lmao

Depending on when VDOT adopted the 2009 MUTCD (the version that included this requirement), signals that didn't follow this rule may have been installed as late as 2013 or 2014 (or even later).


I would actually argue that the arrows are not needed.  There is no oncoming traffic, so no need to indicate a protected turn.  The right arrow does not activate when the cross traffic has the arrow activated to the opposite ramp.
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jakeroot

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Re: Traffic signal
« Reply #2413 on: July 12, 2019, 04:13:32 PM »

I would actually argue that the arrows are not needed.  There is no oncoming traffic, so no need to indicate a protected turn.  The right arrow does not activate when the cross traffic has the arrow activated to the opposite ramp.

I don't disagree. Off-ramps don't need arrows at all, unless there's a desire to use an FYA to protected pedestrians. WA seems to use them as a substitute for lane-use arrows (R3-5 and R3-6): left-only lanes have a left-only arrow; left-and-through lanes have a left arrow and a green orb; etc. Lanes that can go three directions usually get something like what we see in the street view image. There is a signal in Auburn, and another in Burien, that has the same setup as that off-ramp from 525, but they're in tower-form.
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Big John

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Re: Traffic signal
« Reply #2414 on: July 12, 2019, 04:30:27 PM »

^^ The left green arrow should be above the green right arrow

MUTCD:
Section 4D.09 Positions of Signal Indications Within a Vertical Signal Face

03 The relative positions of signal sections in a vertically-arranged signal face, from top to bottom, shall be as follows:

    CIRCULAR RED
    Steady and/or flashing left-turn RED ARROW
    Steady and/or flashing right-turn RED ARROW
    CIRCULAR YELLOW
    CIRCULAR GREEN
    Straight-through GREEN ARROW
    Steady left-turn YELLOW ARROW
    Flashing left-turn YELLOW ARROW
    Left-turn GREEN ARROW
    Steady right-turn YELLOW ARROW
    Flashing right-turn YELLOW ARROW
    Right-turn GREEN ARROW
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jakeroot

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Re: Traffic signal
« Reply #2415 on: July 12, 2019, 04:39:29 PM »

^^ The left green arrow should be above the green right arrow
[cut]

Well that's certainly annoying. I much prefer how WSDOT set it up, as the left and right arrows are horizontally aligned with one-another.

At any rate, this signal doesn't meet new MUTCD guidelines, as it doesn't have a second through signal.
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jakeroot

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Re: Traffic signal
« Reply #2416 on: July 13, 2019, 03:29:19 PM »

Curious what people think of this: https://goo.gl/maps/8WQEYeisRgDNc79Y9

In the link, there's a couple things to notice:

1) the right turn (from the linked approach) is a slip lane
2) there are two left turn lanes at the signal (right lane may go straight)
3) the overhead signals have one green left arrow, one green orb, and one green right arrow (latter two stacked upon each other).

Based on the information, I think the right-green arrow may have been installed facing the wrong direction (right instead of left). There is no indication that right turns are even permitted at the intersection, plus (more importantly) this sort of setup, with two green left arrows and a green orb were very common prior to the 2009 MUTCD for option lane approaches without a dedicated right turn lane, at least in states that don't require pole-mounted signals (such as VA). The signal in the original link was installed in 2013/2014, although the signal may have been designed prior to VDOT's adoption of the 2009 MUTCD.

I managed to find an old photo of the intersection from 2012, taken by our very own 1995hoo. The signal appears to be coming together by 2012. But as I indicated before, that may have been before VDOT adopted the 2009 MUTCD, so although the signal isn't compliant, it may have been acceptable by that point (even with the wrong-way arrow as discussed up-thread).

Edited to add: While I was at the mall I went up to the top of the parking garage out back of where Woodies used to be and took some pictures. Here's the future Westpark Connector exit from the new Express Lanes. The long concrete overpass beyond that is the Metrorail line; you can see in the distance to the right where it swoops around to join the Dulles Access Road Extension in the median.


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mrsman

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Re: Traffic signal
« Reply #2417 on: July 14, 2019, 10:21:16 AM »

^^ The left green arrow should be above the green right arrow
[cut]

Well that's certainly annoying. I much prefer how WSDOT set it up, as the left and right arrows are horizontally aligned with one-another.

At any rate, this signal doesn't meet new MUTCD guidelines, as it doesn't have a second through signal.

True, it isn't compliant with MUTCD, but it's possible that adding only one more additional orb could be problematic.

I agree that people are likely to view the signal as determining lane assignment, so if someone sees a green orb in the left lane, they may assume that they could go straight in the left lane.  But of course, you must turn left in the left lane, you must turn right in the right lane, and can go in any direction in the middle lane.

To be compliant, assuming you can ignore the one signal per lane rule (which I feel is not necessary in many cases), is to have two signal faces.  The left signal face: R-Y-G-GA left.  The right signal face: R-Y-G-GA right.  And a sign to indicate permitted turn movements would be most helpful.  If the third signal is absolutely required, it will be a regular RYG in the middle.
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Re: Traffic signal
« Reply #2418 on: July 14, 2019, 02:42:51 PM »

^^ The left green arrow should be above the green right arrow
[cut]

Well that's certainly annoying. I much prefer how WSDOT set it up, as the left and right arrows are horizontally aligned with one-another.

At any rate, this signal doesn't meet new MUTCD guidelines, as it doesn't have a second through signal.


I would agree.  Given there are two lanes on the ramp, the left is left and through, and the right is right-only, both signals should just be 4-element, with a left arrow on the left one, and a right arrow on the right one, otherwise just 3-elements with orbs would be perfect.
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Re: Traffic signal
« Reply #2419 on: July 14, 2019, 04:43:36 PM »

^^ The left green arrow should be above the green right arrow
[cut]

Well that's certainly annoying. I much prefer how WSDOT set it up, as the left and right arrows are horizontally aligned with one-another.

At any rate, this signal doesn't meet new MUTCD guidelines, as it doesn't have a second through signal.

I would agree.  Given there are two lanes on the ramp, the left is left and through, and the right is right-only, both signals should just be 4-element, with a left arrow on the left one, and a right arrow on the right one, otherwise just 3-elements with orbs would be perfect.

We were referring to this signal (which I cut from my quote): https://goo.gl/maps/B7sEFGDJF8wSMkfK9 -- the center lane of the off-ramp can go three different directions.



True, it isn't compliant with MUTCD, but it's possible that adding only one more additional orb could be problematic.

I agree that people are likely to view the signal as determining lane assignment, so if someone sees a green orb in the left lane, they may assume that they could go straight in the left lane.  But of course, you must turn left in the left lane, you must turn right in the right lane, and can go in any direction in the middle lane.

To be compliant, assuming you can ignore the one signal per lane rule (which I feel is not necessary in many cases), is to have two signal faces.  The left signal face: R-Y-G-GA left.  The right signal face: R-Y-G-GA right.  And a sign to indicate permitted turn movements would be most helpful.  If the third signal is absolutely required, it will be a regular RYG in the middle.

This off-ramp in the Silver Lake neighborhood of Lynnwood, WA was recently re-done. It's an identical setup to my earlier Auburn example, but it does differ slightly: there are two additional signals on either side of the off-ramp (pole-mounted) with green arrows, pointing in respective directions. Overhead, there are two green arrows, and two green orbs (as required). This seems like a fine setup.

I would, realistically, be fine with using just all orbs. Perhaps even having just one overhead green orb, and two on either side of the intersection. I'm trying to find an example of this somewhere in either WA or BC, but both places use right-turn slip lanes at a majority of off-ramps; most, therefore, are only signed for left and straight-through movements.
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Re: Traffic signal
« Reply #2420 on: July 14, 2019, 05:05:39 PM »

Five signal faces seems like overkill to me.

One thing about these ramps is that it seems odd to allow the straight movement altogether.  There are some of these in the L.A. area as well at diamond ramps, but generally they are used to facilitate transit use.  There are some freeway buses that exit, go across the street at the signal, stop to pick up passengers, and then go up the ramp back to the freeway.

Here is an example at US 101 / Van Nuys Blvd.


https://www.google.com/maps/@34.156675,-118.4489662,3a,75y,115.22h,76.57t/data=!3m6!1e1!3m4!1sY3vbS2c84PGzdM08wqc6RQ!2e0!7i16384!8i8192

Here, there are 3 signal faces.   Like Jake's example, left lane for left turns, right lane for right turns, and the center lane for left/straight/right.  The left signal and center signal are RYG-GA left and the right signal is RYG-GA right.  This seems more than sufficient.  The only thing that I would add would be another right arrow onto the middle signal so that it is properly symmetric.

Oddly enough at the opposite off-ramp you have this:

https://www.google.com/maps/@34.1574035,-118.4485884,3a,75y,287.12h,77.71t/data=!3m6!1e1!3m4!1ssqXbaJZkWiLYMfgikaBjDw!2e0!7i16384!8i8192

Same lane configuration.  2 signal faces.  The left signal is RYG-GA left and the right signal is RYG-GA right.  (Not shown in this view is a near side signal that is the same as the signal on the right corner.)

[The old signal configuration had only two RYG signals on each side, without any arrows.  Even this would be sufficient as there is no need for a protected turn off of a one way street (or off-ramp, on-ramp as in this specific case).

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Re: Traffic signal
« Reply #2421 on: July 14, 2019, 08:34:05 PM »

The arrows are probably there to tell drivers there is no conflicting pedestrian movement. That's common in California.
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Re: Traffic signal
« Reply #2422 on: July 14, 2019, 10:00:45 PM »

I stumbled on this temporary traffic signal setup a few nights ago.  Any idea how the cross street signals work?  Are both directions on the main road red so traffic from the cross street can go either direction?  If you were to turn right on red from the right side street, isn't there potential to have a conflict with oncoming traffic if the far end of the bridge had a green light?  This is probably not very likely, since that direction is just a gated driveway, but could be solved by putting up a "NO TURN ON RED" sign.  If NY allowed left turns on red from a two-way street onto a one-way street, would the main street be considered a one way street that keeps changing direction?  If so, the potential for conflicts with traffic from the far end of the bridge could again be eliminated by a "NO TURN ON RED" sign.

Also, I noticed that the far end of the bridge doesn't have a signal for the side street, but I'm assuming people would be smart enough to figure out what direction traffic is going, and that if traffic at this end is stopped, it's to let traffic from the other end cross.  Also, it's a dead end, so the only people on it would be people who live on it and lock employees.
« Last Edit: July 14, 2019, 10:19:21 PM by Michael »
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Re: Traffic signal
« Reply #2423 on: July 14, 2019, 11:34:56 PM »

I stumbled on this temporary traffic signal setup a few nights ago.  Any idea how the cross street signals work?  Are both directions on the main road red so traffic from the cross street can go either direction?  If you were to turn right on red from the right side street, isn't there potential to have a conflict with oncoming traffic if the far end of the bridge had a green light?  This is probably not very likely, since that direction is just a gated driveway, but could be solved by putting up a "NO TURN ON RED" sign.  If NY allowed left turns on red from a two-way street onto a one-way street, would the main street be considered a one way street that keeps changing direction?  If so, the potential for conflicts with traffic from the far end of the bridge could again be eliminated by a "NO TURN ON RED" sign.

Also, I noticed that the far end of the bridge doesn't have a signal for the side street, but I'm assuming people would be smart enough to figure out what direction traffic is going, and that if traffic at this end is stopped, it's to let traffic from the other end cross.  Also, it's a dead end, so the only people on it would be people who live on it and lock employees.



The typical emergency traffic signal to control a single lane bridge would have eastbound traffic as a separate phase from westbound traffic with a sufficiently long all red phase between each direction.  Given that there are intersections so close to the bridge entrances, the westbound phase is further split between River Road and Old Station Road.  Neither side will have green when eastbound has a green.

I would imagine that the feeling was that any forgotten direction would have traffic that is so small as to be negligible.  Not always the best practice, but it may just work here. So that would explain traffic from the the second intersection.

So it means that there is a potential danger from the guy in the private driveway making a right on red.  If this is only one household, perhaps they wrote him a letter explaining the situation and telling him that he would have to get out of his car and push the button and only proceed on green.  And a similar potential danger exists at the second intersection, but again based on the law of averages, the likelihood of traffic is probably very small.

 
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Mark68

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Re: Traffic signal
« Reply #2424 on: July 16, 2019, 02:03:51 PM »

Five signal faces seems like overkill to me.

One thing about these ramps is that it seems odd to allow the straight movement altogether.  There are some of these in the L.A. area as well at diamond ramps, but generally they are used to facilitate transit use.  There are some freeway buses that exit, go across the street at the signal, stop to pick up passengers, and then go up the ramp back to the freeway.

Here is an example at US 101 / Van Nuys Blvd.


https://www.google.com/maps/@34.156675,-118.4489662,3a,75y,115.22h,76.57t/data=!3m6!1e1!3m4!1sY3vbS2c84PGzdM08wqc6RQ!2e0!7i16384!8i8192

Here, there are 3 signal faces.   Like Jake's example, left lane for left turns, right lane for right turns, and the center lane for left/straight/right.  The left signal and center signal are RYG-GA left and the right signal is RYG-GA right.  This seems more than sufficient.  The only thing that I would add would be another right arrow onto the middle signal so that it is properly symmetric.

Oddly enough at the opposite off-ramp you have this:

https://www.google.com/maps/@34.1574035,-118.4485884,3a,75y,287.12h,77.71t/data=!3m6!1e1!3m4!1ssqXbaJZkWiLYMfgikaBjDw!2e0!7i16384!8i8192

Same lane configuration.  2 signal faces.  The left signal is RYG-GA left and the right signal is RYG-GA right.  (Not shown in this view is a near side signal that is the same as the signal on the right corner.)

[The old signal configuration had only two RYG signals on each side, without any arrows.  Even this would be sufficient as there is no need for a protected turn off of a one way street (or off-ramp, on-ramp as in this specific case).



One interesting find in that second setup is that the southbound Van Nuys far left signal (north of 101) still has the old 8-8-12 with the straight arrow in the 12" lens. Looks like a relic of the 60s.
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