Double Doghouse Signals?

[roadfro]

What I would like to see is the adoption of a six-face signal, where there's basically a three-head all-arrow display directly adjacent to a three-head all-orb display (ideally surrounded by a single backplate). These would allow greater flexibility for the above situations where the full functionality of a dedicated turn signal (TOD phasing, pedestrian protection, etc) cannot be afforded due to the option lane, but would allow the placement of an orb display over the option lane. This is currently difficult (basically impossible) to achieve given rules around the physical separation of signals. Plus, there's the issue with left turn signals directly above a lane likely leading drivers to believe that lane to be only for turns (good example here -- virtually zero drivers use the left lane to go straight).

So if the left and middle signals in this example were merged into one 6-section signal... would it work as described above? This intersection has option lanes...

Yikes--isn't it standard not to use the FYA with option lanes like that?  That is one place where doghouses still go up in places that have adopted FYA (e.g., Indiana).

Yes. An all-arrow signal display can only be used over an exclusive left turn lane. For this particular application, the FYA display should be removed and just have the two standard signals maybe with an optional R10-12 (Left turn yield on green [green ball symbol]) sign.

[jakeroot]

What I would like to see is the adoption of a six-face signal, where there's basically a three-head all-arrow display directly adjacent to a three-head all-orb display (ideally surrounded by a single backplate). These would allow greater flexibility for the above situations where the full functionality of a dedicated turn signal (TOD phasing, pedestrian protection, etc) cannot be afforded due to the option lane, but would allow the placement of an orb display over the option lane. This is currently difficult (basically impossible) to achieve given rules around the physical separation of signals. Plus, there's the issue with left turn signals directly above a lane likely leading drivers to believe that lane to be only for turns (good example here -- virtually zero drivers use the left lane to go straight).

So if the left and middle signals in this example were merged into one 6-section signal... would it work as described above? This intersection has option lanes...

Yikes--isn't it standard not to use the FYA with option lanes like that?  That is one place where doghouses still go up in places that have adopted FYA (e.g., Indiana).

Yes. An all-arrow signal display can only be used over an exclusive left turn lane. For this particular application, the FYA display should be removed and just have the two standard signals maybe with an optional R10-12 (Left turn yield on green [green ball symbol]) sign.

Right, to both of you. But that wasn't the point trying to be made: I'd redirect you both to this post on the last page. fwydriver405 was asking if that example (the one in his link) would be a good place to try my conceptual 6-aspect signal (conceptual meaning not permitted by the current MUTCD, by the way...no need to point it out).

As to my opinion: yes, it would be a great place to try it. But I would use post-mounted signals in addition to overhead signals to further enhance that these signals are not meant to be interpreted on a lane-by-lane basis (they are, by design, shared signals -- I don't show it, but I picture a near-side repeater of the right-most signal in my design below to help ensure there is more than one right turn signal):

[mrsman]

I know I mentioned this somewhere else, but DC uses two adjacent signal faces in a similar context to the 6 aspect doghouse:

https://www.google.com/maps/@38.9846804,-77.0266712,3a,37.5y,191.47h,89.05t/data=!3m6!1e1!3m4!1srD922zjgv-iL0LVOAqOk8Q!2e0!7i16384!8i8192

Regular doghouses in DC are rare.  I can't think of any at the moment.  There are HAWKs though, so not every signal in DC is a tower.

The above signal is odd with all three signal faces (left postmounted <zoom out to see>, center on mast arm, right postmounted) having both the thru signal and the left arrow signal.  I can see the need for two signal faces, but I don't understand why the left arrows are displayed on the right postmount.

This signal, a short distance away, is even worse.  5 aspect towers with left turn arrows on both the left and right postmounts, but not on the mast arms. 

https://www.google.com/maps/@38.9785017,-77.0184569,3a,37.5y,248.8h,81.18t/data=!3m6!1e1!3m4!1sIdA76-5WtI1kxarYixeJEw!2e0!7i16384!8i8192

I don't recall DC using their very short mast arms on any signal face taller than 3 aspects.  The very common 4 aspect and 5 aspect signal faces on towers all seem to be postmounted [or on heavy-duty mast arms that exist in some places, usually near the freeway entrances].

[jakeroot]

^^
That signal along Georgia Ave is definitely quite odd. I think they could improve it by considering a design like the concept I presented above: the right-most signal could instead use a right-facing arrow for pedestrian protection (which could then also be repeated near-side), swapping the placement of course.

The use of green orbs on all corners, even with fully protected turns, seems to be an art practiced only in DC from what I've seen.

Seriously, this is by far the most Australian-looking intersection I've ever seen in the US, and there doesn't seem to be a close second (apart from a couple other DC intersections):

[Flyer78]

Here is one in Camillus/Fairmount NY, Onondaga Rd crossing West Genesee St.
https://www.google.com/maps/@43.0469388,-76.2388018,3a,90y,9.58h,84.83t/data=!3m7!1e1!3m5!1sUym5iaDOFUAkbMt7afiRXg!2e0!5s20190801T000000!7i16384!8i8192

Mast arm install, I think was put up early 2000s... Lane guidance on the mast arm. Also, street names mounted overhead, which is not common in the area (then again, most along W. Gensesee St in the area are wire-span.)


From Springfield PA, Sproul Rd at Baltimore Pike
https://www.google.com/maps/@39.913576,-75.3494137,3a,75y,206h,87.64t/data=!3m6!1e1!3m4!1sQUpbhs5Mh1AAMWHAmFm5MQ!2e0!7i16384!8i8192

The right arrow comes on during the yellow phase, I guess to encourage right-turning traffic to continue. Note the vintage "Right turn on red after stop" still extant.

[mrsman]

^^^^^^^

Whenever leading left of the cross traffic direction follows the phase of green, it is helpful to have green right arrow during yellow.  It essentially tells cars to keep going and makes the right turns continuous.  Query whether yellow + green arrow occurs at all times or only if there is no pedestrian who pushes the button.  Technically, the pedestrian clearance interval (FDW) and countdown timers are supposed to stop before the yellow signal.  Peds are not supposed to be crossing during yellow, but realistically, the yellow phase does provide a last few seconds for people to cross.  Knowing this, I do wonder if they would still put in place a green arrow on yellow if the pedestrian call has been activated.

A signal in my area (at a T intersection) also produces a green arrow with yellow ball when cross street gets a leading left, but there, peds are prohibited from crossing on that side of the street anyway (and green arrow is always lit with green ball).

https://www.google.com/maps/@39.0470333,-77.0484935,3a,75y,0.92h,75.18t/data=!3m6!1e1!3m4!1sg62ffRYsBh_iGJ_1xZhyPQ!2e0!7i13312!8i6656

To stay on topic, one block away, there is a double doghouse:

https://www.google.com/maps/@39.0471569,-77.0517774,3a,75y,299.81h,79.17t/data=!3m6!1e1!3m4!1sYqq-p_1n0aKz8UbCOT7ryg!2e0!7i16384!8i8192

[Caps81943]

I don't recall DC using their very short mast arms on any signal face taller than 3 aspects.  The very common 4 aspect and 5 aspect signal faces on towers all seem to be postmounted [or on heavy-duty mast arms that exist in some places, usually near the freeway entrances].

I think there's a very few small mast arms with doghouses scattered throughout the city, but can't recall where.

[roadfro]

Whenever leading left of the cross traffic direction follows the phase of green, it is helpful to have green right arrow during yellow.  It essentially tells cars to keep going and makes the right turns continuous.  Query whether yellow + green arrow occurs at all times or only if there is no pedestrian who pushes the button.  Technically, the pedestrian clearance interval (FDW) and countdown timers are supposed to stop before the yellow signal.  Peds are not supposed to be crossing during yellow, but realistically, the yellow phase does provide a last few seconds for people to cross.  Knowing this, I do wonder if they would still put in place a green arrow on yellow if the pedestrian call has been activated.

Per MUTCD (figure 4E-2), the pedestrian phasing *can* extend into into the yellow part of the vehicle phase. You can even use part of the red clearance for pedestrian clearance, so long as there is a minimum 3 second buffer before conflicting traffic gets their green. With that said, it does appear that most agencies do set up phasing so the pedestrian countdown coincides with the onset of yellow (or ends before yellow).

[mrsman]

Whenever leading left of the cross traffic direction follows the phase of green, it is helpful to have green right arrow during yellow.  It essentially tells cars to keep going and makes the right turns continuous.  Query whether yellow + green arrow occurs at all times or only if there is no pedestrian who pushes the button.  Technically, the pedestrian clearance interval (FDW) and countdown timers are supposed to stop before the yellow signal.  Peds are not supposed to be crossing during yellow, but realistically, the yellow phase does provide a last few seconds for people to cross.  Knowing this, I do wonder if they would still put in place a green arrow on yellow if the pedestrian call has been activated.

Per MUTCD (figure 4E-2), the pedestrian phasing *can* extend into into the yellow part of the vehicle phase. You can even use part of the red clearance for pedestrian clearance, so long as there is a minimum 3 second buffer before conflicting traffic gets their green. With that said, it does appear that most agencies do set up phasing so the pedestrian countdown coincides with the onset of yellow (or ends before yellow).

Thank you for that.  I was basing my comment more on observation than on a technical reading of the MUTCD.

So if a 3 second buffer is required, and if it is typical for the 3 second buffer to coincide with the yellow phase of the signal, would it be fair to conclude that the yellow signal and green arrow would not be lit together even preceding a leading green arrow on the cross street when pedestrians are crossing with the green orb signal?

The 3 second buffer is intereting in another context.  Pre-COVID, I would regularly cross at a Barnes Dance.  It seemed to me that the traffic on one of the streets was released immediately after the countdown went down to zero, so watch out.  This seems to be a violation of this rule.  (Other normal nearby intersections don't have this problem as the yellow comes on after the countdown comes down to zero, which provides at least a 3 second buffer.  I could tell you that when you are used to having a grace period of a few seconds after the countdown timer gets to zero, not having at a Barnes Dance put in place primarily for PEDESTRIAN SAFETY can be jarring.)

[jakeroot]

For an example of the FDW phase extending not only into the solid yellow, but also the red phase, see this intersection in Tacoma, WA. The all-red phase is about two seconds, standard for the city.

A video I made a little while back:

https://youtu.be/MXXuUl3WfQM

[fwydriver405]

Here's an example of three post mounted doghouses in Newton MA.

Whenever leading left of the cross traffic direction follows the phase of green, it is helpful to have green right arrow during yellow.  It essentially tells cars to keep going and makes the right turns continuous.  Query whether yellow + green arrow occurs at all times or only if there is no pedestrian who pushes the button.  Technically, the pedestrian clearance interval (FDW) and countdown timers are supposed to stop before the yellow signal.  Peds are not supposed to be crossing during yellow, but realistically, the yellow phase does provide a last few seconds for people to cross.  Knowing this, I do wonder if they would still put in place a green arrow on yellow if the pedestrian call has been activated.

But if the oncoming left turn(s) were permissive, would that cause yellow trap for the permissive left turns who entered the intersection on green or yellow during the clearance phase since the right turns don't stop at all? Sources: 1, 2, and replies 111-122 in this thread.

[mrsman]

Here's an example of three post mounted doghouses in Newton MA.

Whenever leading left of the cross traffic direction follows the phase of green, it is helpful to have green right arrow during yellow.  It essentially tells cars to keep going and makes the right turns continuous.  Query whether yellow + green arrow occurs at all times or only if there is no pedestrian who pushes the button.  Technically, the pedestrian clearance interval (FDW) and countdown timers are supposed to stop before the yellow signal.  Peds are not supposed to be crossing during yellow, but realistically, the yellow phase does provide a last few seconds for people to cross.  Knowing this, I do wonder if they would still put in place a green arrow on yellow if the pedestrian call has been activated.

But if the oncoming left turn(s) were permissive, would that cause yellow trap for the permissive left turns who entered the intersection on green or yellow during the clearance phase since the right turns don't stop at all? Sources: 1, 2, and replies 111-122 in this thread.

Yes.  You are correct, there is still the possibility of a yellow trap problem for opposing permissive left turns.  I participated in that earlier thread and it seems as if my answer there were more precise to account for that possibility:

It is only dangerous where there is a conflict.  If the next signal phase is a leading protected left turn for cross traffic, green arrow + yellow would be OK so long as there is no pedestrian conflict or conflict with opposing left turns.  In most cases, if pedestrians could cross there, they face a solid hand (DON'T WALK) when yellow comes on, so that would not normally be the problem.  Jakeroot properly identified the conflict with opposing permissive left turns that could exist.  But in situations where there is no conflict (opposing left prohibited, opposing left restricted to protected only, or no opposing left [T-intersections]), this is actually helpful to keep traffic flowing.

[plain]

Double doghouses, specifically where only 2 such signals are controlling a particular direction, are more common than many may think. There are many examples in Virginia alone.

But what about dual-facing doghouses?

Here's a former example in Hampton, VA that stood for years. Actually there's dual-facing 5-section towers at the same intersection (both pictured below). Sadly, those doghouses where knocked down by some idiot last month and they were replaced with 5-sections to match what is across the street.

US 258 Mercury Blvd at Woodland Rd

Can still be seen on GSV




moto g(7) optimo (XT1952DL)

[Caps81943]

Brandon has Illinois covered, but I thought I'd add a fun little bonus fact-- here's an intersection where EVERY SINGLE APPROACH is a double-tower.  And there isn't a SINGLE three-section head at the entire intersection!  I'm sure this isn't the only place where this has happened in Illinois, either! https://goo.gl/maps/gnnvQg271boWT2Tz8

Found another one in Montgomery, NY at Highways 17K and 208. Two doghouses in each direction for a total of eight doghouses on one span wire.

https://www.google.com/maps/@41.5255536,-74.2005546,3a,43.5y,266.33h,89.77t/data=!3m6!1e1!3m4!1sUHY2Ng0kBQCYth12MS35yw!2e0!7i16384!8i8192

[democratic nole]

I am not a fan of the aesthetics of the doghouse signal and hope that with FYA's, we will start to see them go away. For the life of me, I do not understand the doghouse signal being used on a pedestal mount. It looks god-awful.

Attached is a double doghouse for left turn in Tampa. https://goo.gl/maps/PiwMtiKKfXFVJVyH8. This originally features dual horiztonal-5 in-line left turn signals, but my guess is the expressway authority determined that those were more confusing to drivers and installed these instead. Because this intersection enters reversible express lanes, a driver could only drive straight here at certain times of the day.

[RobbieL2415]

A ConnDOT example about a mile from my apartment.
Photo is old but it shows that this intersection has had double doghouses for a while. Old and new side-by-side.
https://goo.gl/maps/DQYg36QeTy8C57Gv5

[mrsman]

Brandon has Illinois covered, but I thought I'd add a fun little bonus fact-- here's an intersection where EVERY SINGLE APPROACH is a double-tower.  And there isn't a SINGLE three-section head at the entire intersection!  I'm sure this isn't the only place where this has happened in Illinois, either! https://goo.gl/maps/gnnvQg271boWT2Tz8

Found another one in Montgomery, NY at Highways 17K and 208. Two doghouses in each direction for a total of eight doghouses on one span wire.

https://www.google.com/maps/@41.5255536,-74.2005546,3a,43.5y,266.33h,89.77t/data=!3m6!1e1!3m4!1sUHY2Ng0kBQCYth12MS35yw!2e0!7i16384!8i8192

The way this intersection is laid out, it allows for maximum mobility for each direction of traffic and each turning direction.  There is a lane for each direction (left, straight, right) on each approach.  Right turn green arrows to correspond with each protected left.  Right turns can go without being blocked at all opportunities: RTOR during cross traffic green (and opposing protected lefts), RT on green with yield to peds, and right turn protected during corresponding cross traffic lefts.  Protected/permissive lefts.

[Amtrakprod]

A ConnDOT example about a mile from my apartment.
Photo is old but it shows that this intersection has had double doghouses for a while. Old and new side-by-side.
https://goo.gl/maps/DQYg36QeTy8C57Gv5

Hey I've been there!


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