Ad/Disadvantage of A Doghouse Permissive L/R vs. A 5 Section Permissive L/R

[TheArkansasRoadgeek]

So, I see both Doghouse and 5 Section permissive L/R turns signals use interchangably, so what is more common among states? I don't see very many (if any) Doghouse style in Fort Smith, but Little Rock is a diverse array of both 5 section and doghouse turning styles. Is one used for clearance reasons and the other not so much? Like, the doghouse is very compact and the 5 section isn't.

Any thoughts?

Thanks!

[Brandon]

Illinois (IDOT, CDOT, counties, municipalities) uses the 5-section tower exclusively (other than some FYAs in Peoria, Springfield, and Kane County).  The tower can be placed against a pole rather nicely, and IDOT District 1 (Schaumburg) tends to place the signals on the lane lines as opposed to directly above the lanes.

Examples:
https://goo.gl/maps/hHwcGbGoKzR2
https://goo.gl/maps/pcHH8nLqF9N2
https://goo.gl/maps/yW1BUxqexDz

[paulthemapguy]

Doghouses are typically used in regions dominated by signals strung up on cables or wires, because they allow you to keep a consistent vertical spacing between the two wires supporting the signal heads.  If there was a mix of signal heads 3 sections tall and others that are 5 sections tall, you couldn't space the wires apart such that they both run across the intersection at a consistent height.  I find that the states using strung-up signals are pretty much the states in the Eastern Time Zone; these states will all pretty much use doghouses.  There are also states, however, that use mast arms AND doghouses, like Missouri.  This is just my general take on things.

I can also vouch for the fact that you won't find a single doghouse in Illinois.

[ilpt4u]

There is a Cable/Wire/Strand mounted signal in Du Quoin, IL, on US 51, that uses the Tower (because it is still IL and IDOT) -- I thought it looked kinda weird. The adjacent 3 Signal Head fixture had an extension bar extending it down farther, so the bottom support stand matched up with the 5 Signal Tower fixture

On GSV: https://goo.gl/maps/9E7zAp8RNb12

As far as a single doghouse in IL, there is one in Naperville at least, leaving the Naperville Children's Museum at Washington St, just south of the Metra/Amtrak station. It is not your typical doghouse tho, as the Museum's Exit onto Washington must turn on Washington -- no straight movement at the intersection, as North Avenue is Westbound One Way into the Museum and towards Washington (mostly due to the nearby Train Station, for Commuters to exit). Since there is no Straight movement (the GSV has the not commonly used straight arrow thru a red circle signed), the "Green" phases of the Doghouse are all arrows -- Green/Yellow Left, and Green/Yellow Right

On GSV: https://goo.gl/maps/hiRoYmyNr2D2

[jakeroot]

Here in Washington, the two most common PPLT displays are the doghouse and the 4-section tower (other than FYAs, which are probably the most common PPLT display today -- traditional green-orb PPLT displays aren't really installed anymore). 5-section towers are pretty rare.

A few local oddities and other examples:

- Spokane uses doghouses for almost all left and right turn displays that aren't protected, even those mounted on poles (which are required)
--> Examples: https://goo.gl/KChxCN --&-- https://goo.gl/Bq4pPZ (rare 5-section tower also visible)

- Tacoma, up until recently, attached the green/yellow arrow displays below the far-left signal when changing a fully permissive left into a PPLT. This resulted in many 5-section towers across the city (4-section also common).
--> Examples: https://goo.gl/82L3vF --&-- https://goo.gl/a2W7uq
--> There are many examples of wire-spun 4- and 5-section towers throughout the city.

- Snohomish County, plus most cities within, use 4-section bi-modal signals for most PPLT displays. Many other cities outside of Snohomish County also use 4-section signals (too many to count), often for right-turn filters.
--> Examples: https://goo.gl/hndLE3 --& -- https://goo.gl/1qYfwW --&-- https://goo.gl/HWVFVg --&-- https://goo.gl/nXjZoW

[Brandon]

4-section bi-modal signals used to be more common in Illinois, and they can still be found from time to time, most often in Rockford.

Examples:
https://goo.gl/maps/fJjgnNaJQ5H2
https://goo.gl/maps/72P1arvs9QN2

Chicago uses 4-section towers, but they have the green arrow come on after opposing traffic has turned red and simply use the yellow ball at the end of the cycle.  They are not bi-modal.

Examples:
https://goo.gl/maps/ju42xSZnFCQ2
https://goo.gl/maps/r31TNAYR3o42

Then there are the CDOT MUTCD violations:
https://goo.gl/maps/HNKw7YJLPiy

[TheArkansasRoadgeek]

This intersection: https://goo.gl/Fwqzgk, in Little Rock is one that features an array of 5 sections and one doghouse perm-right turn. But, if 5 sections aren't as common (nowadays) come to Fort Smith sometime! Up and down US 71 you'll see them to no end! (and in areas of Fort Smith)

[plain]

There used to be numerous 5-section towers in a few Virginia cities but they are becoming a rare sight now, having been replaced by doghouses (and some of those doghouses were later replaced by FYA's). Today the most examples of 5-section towers are found in Danville, mostly for right turn movements.

Some towers outside of Danville that I know still exist..


Newport News:

VA 143/US 17 just NW of US 258
https://goo.gl/maps/VUGYdHVdHRE2

Briarfield Rd @ Marshall Ave
https://goo.gl/maps/p7nHmKwGkX62

US 60 Warwick Blvd (mounted on a pole in the median)
https://goo.gl/maps/JjUWNZjWnCx


Richmond:

VA 33 (NOT US 33 as the trailblazer in the image suggests) Leigh St. This one replaced a 4-section where the green arrow appeared after the signal for oncoming traffic turned red.
https://goo.gl/maps/Rtphtuz7rmR2

US 1/301 Jeff Davis Hwy. There are towers in both directions of this image. They are mounted on the median and apply only to turning traffic
https://goo.gl/maps/enBrBhVxMZu

Right turn tower on Grove Ave @ Three Chopt Rd, mounted on a pole
https://goo.gl/maps/VtAr2emn3F92


Williamsburg:

And lastly my favorite, where US 60 and VA 5 currently meet east of central Williamsburg. Numerous towers side mounted and they all display left turn arrows
https://goo.gl/maps/rwndDzvGA1Q2

[roadfro]

Note that the thread title should be a bit different. A "Doghouse" signal has 5 sections. It seems what was meant here was a 5-section doghouse versus a 5-section horizontal or 5-section vertical signal head.



Nevada's PPLT standard has been to use doghouses on the mast arms with a 5-section vertical on the far left pole for the supplemental signal. Since the advent of FYA, however, PPLTs primarily use the 4-section FYA signal on both the mast arm and the far left pole (although 3-section FYAs with bimodal arrow are used in some instances with clearance issues).

Using a doghouse on the mast arm signal, I believe, results in less surface area for wind loading and, in my opinion, results in a cleaner appearance. Similarly, using the 5-section vertical on a pole mount installation is more secure and has the cleaner appearance. 5-section verticals on a mast arm look weird to me, especially since the similar signal indications don't typically line up.

[Bitmapped]

West Virginia uses modified doghouses exclusively. WVDOH standard is 2-section arrow beside a 3-section RYG, although occasionally you'll see a traditional doghouse pop-up as the result of contractor error.

[cl94]

New York has very little consistency whatsoever, in that if a PPLT configuration exists (sans Michigan's flashing red ball), you'll probably find it somewhere in NY. Depending on the AHJ, protected/permissive signals could be:

-Doghouses (generally the standard in New York outside of NYC and Long Island)
-Side-by-side modified doghouses (almost exclusively in Nassau and Suffolk and used by all agencies there; only a few doghouses exist on Long Island)
-5-section towers (mainly NYCDOT and Nassau County DPW, but certainly found elsewhere)
-4-section bimodals (most common in Western New York, but found all over). Erie and Monroe County DPWs still use these exclusively.
-What I will call "frankendoghouses" such as this (almost ALWAYS installed by a town)
-More recently, FYAs (generally NYSDOT Regions 1, 2, 4, 6 and 7 but becoming more common elsewhere). These appear to be the new standard for all regions other than 3, 8 and 9.
-At least one location (NY 104 in Wayne County) has a flashing RED arrow.

[dfnva]

There used to be numerous 5-section towers in a few Virginia cities but they are becoming a rare sight now, having been replaced by doghouses (and some of those doghouses were later replaced by FYA's). Today the most examples of 5-section towers are found in Danville, mostly for right turn movements.

Some towers outside of Danville that I know still exist..


Newport News:

VA 143/US 17 just NW of US 258
https://goo.gl/maps/VUGYdHVdHRE2

Briarfield Rd @ Marshall Ave
https://goo.gl/maps/p7nHmKwGkX62

US 60 Warwick Blvd (mounted on a pole in the median)
https://goo.gl/maps/JjUWNZjWnCx


Richmond:

VA 33 (NOT US 33 as the trailblazer in the image suggests) Leigh St. This one replaced a 4-section where the green arrow appeared after the signal for oncoming traffic turned red.
https://goo.gl/maps/Rtphtuz7rmR2

US 1/301 Jeff Davis Hwy. There are towers in both directions of this image. They are mounted on the median and apply only to turning traffic
https://goo.gl/maps/enBrBhVxMZu

Right turn tower on Grove Ave @ Three Chopt Rd, mounted on a pole
https://goo.gl/maps/VtAr2emn3F92


Williamsburg:

And lastly my favorite, where US 60 and VA 5 currently meet east of central Williamsburg. Numerous towers side mounted and they all display left turn arrows
https://goo.gl/maps/rwndDzvGA1Q2

In the 1980s, and into the 1990s, VDOT, itself, installed five-section towers for protected right turns in numerous locations. Some still exist in the Richmond suburbs.

In Northern Virginia, I recall, specifically, VDOT-installed 5-light towers, for this purpose, were used:
- VA-286/Fairfax County Pkwy where it ends at US-1 (recently removed with construction, https://goo.gl/maps/HwsUykqaFe62).
- SR-644/Keene Mill Rd west at Carleigh Pkwy, West Springfield (removed/replaced with doghouse signal in the early 1990s).
- Bland St. east at Amherst Ave, Springfield (signal assembly replaced in the early 2000s with construction).

VDOT traditionally installs doghouse signals or three-section signals for protected right turn movements. I don't recall any VDOT-installed 5-light towers for protected left turns. 

Though not VDOT-installed, Arlington County likes using five-light towers for redundant pole- or pedestal-mounted signals for protected left-turn movements.
Some examples: https://goo.gl/maps/qxNDcFjQHiq, https://goo.gl/maps/JUAPfj5TRow

[jakeroot]

....VDOT, itself, installed five-section towers for protected right turns in numerous locations....

.....VDOT traditionally installs doghouse signals or three-section signals for protected right turn movements. I don't recall any VDOT-installed 5-light towers for protected left turns.....

....Arlington County likes using five-light towers for redundant pole- or pedestal-mounted signals for protected left-turn movements.

Not to get nitpicky, but your terminology is confusing, to the say the least. Protected turn signals are all-arrow installations that have no permissive ('yield') phase. These 4-/5-section 'yield on green' signals (the ones being discussed in this thread) are protective/permissive signals. Unless an arrow is displayed, you are yielding. There is no protection being afforded outside of when an arrow is displayed.

I suspect that, in most every instance, you meant 'dedicated left turn lane' or 'dedicated right turn lane', or some variation thereof.

I think the distinction is important due to the existence of 5-section protected only signals. I've seen them in both Colorado and Washington State, where a protective/permissive signal was converted to protected-only.

[Revive 755]

Illinois (IDOT, CDOT, counties, municipalities) uses the 5-section tower exclusively (other than some FYAs in Peoria, Springfield, and Kane County).

Jacksonville and Rockford can be added to the list of towns with FYAs. 

Rumor has it there will be a few more doghouses popping up in Illinois in the future.

Before the use of FYAs, Iowa was mostly 5-section towers, though a few cities such as Iowa City and Council Bluffs would use doghouses.

Using a doghouse on the mast arm signal, I believe, results in less surface area for wind loading and, in my opinion, results in a cleaner appearance.

The one time I tried to calculate the area for a doghouse versus a tower, the area difference was fairly small.  More likely the difference will be exceeded by any signs used on the mast arm.

Also, I believe doghouses and other cluster arrangements may require different mounting brackets than a tower design.

However to me the doghouses look much better for overhead mounted signals.

[jakeroot]

Using a doghouse on the mast arm signal, I believe, results in less surface area for wind loading and, in my opinion, results in a cleaner appearance.

The one time I tried to calculate the area for a doghouse versus a tower, the area difference was fairly small.  More likely the difference will be exceeded by any signs used on the mast arm.

I think it's less about surface area, and more about the shape and the layout. The more square shape of the doghouse (assuming there's a back plate) is, perhaps, less prone to bending, and therefore failure. Plus, all but one signal head (the red orb) is attached to at least three other signal heads, so there's more redundancy (if one fails, the chance of the entire assembly failing is less than with a tower).

That said, I am not a traffic engineer. This is just my analysis from a layman's perspective.

FWIW, the doghouse back plate (of the non-cutout variety) should have more surface area, due to the redundant border left and/or right of the red orb.

[cl94]

FWIW, the doghouse back plate (of the non-cutout variety) should have more surface area, due to the redundant border left and/or right of the red orb.

I have only seen non-cutout backplates recently in one state: West Virginia. Out here, cutouts are generally used.

[jakeroot]

FWIW, the doghouse back plate (of the non-cutout variety) should have more surface area, due to the redundant border left and/or right of the red orb.

I have only seen non-cutout backplates recently in one state: West Virginia. Out here, cutouts are generally used.

Exact opposite out west. I see cutout backplates here in Washington from time to time, but the square style far, far outweighs the number of cutout backplates. AFAIK, the square backplate is the standard in all states west of at least Colorado, if not farther east.

[TheArkansasRoadgeek]

Note that the thread title should be a bit different. A "Doghouse" signal has 5 sections. It seems what was meant here was a 5-section doghouse versus a 5-section horizontal or 5-section vertical signal head.

True, see I wasn't thinking in those terms. I want to expand my knowledge of intersection configurations and termonology outside of the MUTCD. Slowly, but surely!

[TheArkansasRoadgeek]

Exact opposite out west. I see cutout backplates here in Washington from time to time, but the square style far, far outweighs the number of cutout backplates. AFAIK, the square backplate is the standard in all states west of at least Colorado, if not farther east.

At least in Little Rock, (where most commonly used) they use doghouses for almost all PPLT and/or 5 section setup. With the doghouse it is either louvered (if you will, or vented) for less wind resistance, or solid back plate.

[jakeroot]

Exact opposite out west. I see cutout backplates here in Washington from time to time, but the square style far, far outweighs the number of cutout backplates. AFAIK, the square backplate is the standard in all states west of at least Colorado, if not farther east.

At least in Little Rock, (where most commonly used) they use doghouses for almost all PPLT and/or 5 section setup. With the doghouse it is either louvered (if you will, or vented) for less wind resistance, or solid back plate.

Are most of the doghouse backplates square, or do they follow the lines of the signal layout (quite literally, cut-out)?

[TheArkansasRoadgeek]

Exact opposite out west. I see cutout backplates here in Washington from time to time, but the square style far, far outweighs the number of cutout backplates. AFAIK, the square backplate is the standard in all states west of at least Colorado, if not farther east.

At least in Little Rock, (where most commonly used) they use doghouses for almost all PPLT and/or 5 section setup. With the doghouse it is either louvered (if you will, or vented) for less wind resistance, or solid back plate.

Are most of the doghouse backplates square, or do they follow the lines of the signal layout (quite literally, cut-out)?

Both, but it just depends on where you are/go within the city. Most, are square, but you'll come across a few without a back plate (like the doghouse shown in the maps link (W. Markham St. & Shackleford Rd.)).

[jakeroot]

Exact opposite out west. I see cutout backplates here in Washington from time to time, but the square style far, far outweighs the number of cutout backplates. AFAIK, the square backplate is the standard in all states west of at least Colorado, if not farther east.

At least in Little Rock, (where most commonly used) they use doghouses for almost all PPLT and/or 5 section setup. With the doghouse it is either louvered (if you will, or vented) for less wind resistance, or solid back plate.

Are most of the doghouse backplates square, or do they follow the lines of the signal layout (quite literally, cut-out)?

Both, but it just depends on where you are/go within the city. Most, are square, but you'll come across a few without a back plate (like the doghouse shown in the maps link (W. Markham St. & Shackleford Rd.)).

When I say "cut out", I mean something like this: https://goo.gl/maps/apSjCdbU22E2

[US 89]

Utah uses mast arms almost exclusively (the only wire signals I can think of are in Salt Lake City on some city-maintained roads). The PPLT signal here is nearly always a doghouse, usually without a backplate. If there is a backplate, it is the non-cutout one. If there is a pole mount (relatively rare), it will usually be the 5 section vertical.

However, there is at least one 5-section PPRT signal on the mast arm in St. George, and there are a few pole-mounted PPRT doghouses scattered around.

[Bitmapped]

FWIW, the doghouse back plate (of the non-cutout variety) should have more surface area, due to the redundant border left and/or right of the red orb.

I have only seen non-cutout backplates recently in one state: West Virginia. Out here, cutouts are generally used.

West Virginia has used cutout backplates for a number of years. Most cut-out ones in service are older non-reflective installs, although new ones occasionally go up as contractor installs.

[TheArkansasRoadgeek]

Exact opposite out west. I see cutout backplates here in Washington from time to time, but the square style far, far outweighs the number of cutout backplates. AFAIK, the square backplate is the standard in all states west of at least Colorado, if not farther east.

At least in Little Rock, (where most commonly used) they use doghouses for almost all PPLT and/or 5 section setup. With the doghouse it is either louvered (if you will, or vented) for less wind resistance, or solid back plate.

Are most of the doghouse backplates square, or do they follow the lines of the signal layout (quite literally, cut-out)?

Both, but it just depends on where you are/go within the city. Most, are square, but you'll come across a few without a back plate (like the doghouse shown in the maps link (W. Markham St. & Shackleford Rd.)).

When I say "cut out", I mean something like this: https://goo.gl/maps/apSjCdbU22E2

So, with an inductive sensor and/or pressure plate? I thought "cut out" was referring to the back plate... Oops