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Traffic signal

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

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roadfro

Quote from: jakeroot on July 04, 2019, 03:29:50 AM
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.
Roadfro - AARoads Pacific Southwest moderator since 2010, Nevada roadgeek since 1983.


mrsman

Quote from: jakeroot on July 04, 2019, 03:29:50 AM
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.

jakeroot

Quote from: roadfro on July 04, 2019, 02:19:36 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...

Quote from: mrsman on July 04, 2019, 02:26:34 PM
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.

CJResotko


TEG24601

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
They said take a left at the fork in the road.  I didn't think they literally meant a fork, until plain as day, there was a fork sticking out of the road at a junction.

mrsman

Quote from: TEG24601 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




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.

TEG24601

The left one was just a green arrow.  The right one had a green ball and a green arrow.
They said take a left at the fork in the road.  I didn't think they literally meant a fork, until plain as day, there was a fork sticking out of the road at a junction.

plain

#2407
Quote from: TEG24601 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

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.
Newark born, Richmond bred

jakeroot

Quote from: plain on July 11, 2019, 07:44:51 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.

Quote from: TEG24601 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

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

plain

Quote from: jakeroot on July 11, 2019, 08:35:23 PM
Quote from: plain on July 11, 2019, 07:44:51 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
Newark born, Richmond bred

traffic light guy

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

LG-M327


jakeroot

Quote from: plain on July 11, 2019, 09:26:33 PM
Quote from: jakeroot on July 11, 2019, 08:35:23 PM
Quote from: plain on July 11, 2019, 07:44:51 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).

TEG24601

Quote from: jakeroot on July 12, 2019, 04:03:42 AM
Quote from: plain on July 11, 2019, 09:26:33 PM
Quote from: jakeroot on July 11, 2019, 08:35:23 PM
Quote from: plain on July 11, 2019, 07:44:51 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.
They said take a left at the fork in the road.  I didn't think they literally meant a fork, until plain as day, there was a fork sticking out of the road at a junction.

jakeroot

Quote from: TEG24601 on July 12, 2019, 12:09:36 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.

Big John

^^ 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

jakeroot

Quote from: Big John on July 12, 2019, 04:30:27 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.

jakeroot

Quote from: jakeroot on July 04, 2019, 03:29:50 AM
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).

Quote from: 1995hoo on April 26, 2012, 04:09:36 PM
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.



mrsman

Quote from: jakeroot on July 12, 2019, 04:39:29 PM
Quote from: Big John on July 12, 2019, 04:30:27 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.

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.

TEG24601

Quote from: jakeroot on July 12, 2019, 04:39:29 PM
Quote from: Big John on July 12, 2019, 04:30:27 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.
They said take a left at the fork in the road.  I didn't think they literally meant a fork, until plain as day, there was a fork sticking out of the road at a junction.

jakeroot

Quote from: TEG24601 on July 14, 2019, 02:42:51 PM
Quote from: jakeroot on July 12, 2019, 04:39:29 PM
Quote from: Big John on July 12, 2019, 04:30:27 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.




Quote from: mrsman on July 14, 2019, 10:21:16 AM
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.

mrsman

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).


SignBridge

The arrows are probably there to tell drivers there is no conflicting pedestrian movement. That's common in California.

Michael

#2422
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.

mrsman

Quote from: Michael 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.



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.


Mark68

Quote from: mrsman 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).



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.
"When you come to a fork in the road, take it."~Yogi Berra



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