Permissive 5-section signal head placement on mast arms or span wires

[Hobart]

So driving around the south of Chicagoland, I noticed that the local jurisdictions like to change up where they put their left turn signal heads when using the 5-stacked towers. I also noticed that other areas are a lot more consistent with how they place them on the mast arm.

So which one do you guys like?

I threw in some examples in case you folks want them.
Above the left turn lane?
This one is from 191st and 80th in Mokena, IL: https://www.google.com/maps/@41.5436249,-87.8125225,3a,47.9y,84.99h,94.42t/data=!3m6!1e1!3m4!1sNr2XNzC0U5pWgKp7CfdHCg!2e0!7i16384!8i8192

Between the left turn and the leftmost thru lane?
This one's at 159th and Oak Park Avenue in Tinley Park, IL:
https://www.google.com/maps/@41.6021236,-87.7853175,3a,43.6y,14.72h,94.35t/data=!3m6!1e1!3m4!1sXD1jHEKowfXwo2dAjIPOtQ!2e0!7i16384!8i8192

Or above the left thru lane?
This is at 159th and Pulaski in Markham, IL:
https://www.google.com/maps/@41.6036251,-87.7169781,3a,75y,241.2h,101.04t/data=!3m7!1e1!3m5!1sIQxEAEzuf2FwcBfOfyBUoQ!2e0!5s20180801T000000!7i16384!8i8192

I like putting the permissive protected head for left turns above the left turn lane. Honestly, I think the arrangement at 191st and 80th would be the ideal configuration if they put a supplemental signal on the far side pole. If it's just a left turn lane and a through lane though, I think putting the head between the two lanes would work fine.

(Also yes, I know this is getting increasingly arbitrary as the flashing yellow arrow takes over our lives, I'm just curious.)

[jakeroot]

My preference is generally for a single overhead signal, with all other signals being mounted on poles.

The overhead signal, ideally, would be mounted in the center of the approach. Left + through lane = between the two lanes; left + two through lanes = directly over left through lane (example of what I like in Skokie, IL)

More than three approach lanes, and I would have the 5-section signal mounted between the left and through lane, with the other signal being centered between the right-most through lanes. Five or more lanes, couldn't quite say.

[roadfro]

My preference is for this type of signal to be mounted between the left turn lane and the left-most through lane.

Note that as of the 2009 MUTCD, this type of signal face is not allowed to be positioned over a separate left turn lane if the signal operates in protected mode.

[ran4sh]

That is correct, the intent in the 2009 MUTCD is for FYA or protected-only signals to be above or in front of left-turn lanes.

Doghouses/5-section signals are recommended to be positioned above the line that separates the left-turn lane from the thru lane. This also emphasizes that it is a shared left/thru signal rather than a signal that only applies to left-turning traffic.

My opinion is that they should generally all be removed and replaced with FYA signals. In some cases this also requires an additional thru signal so that (1) there are 2 of them as required, and/or (2) there is 1 thru signal per thru lane as recommended.

[paulthemapguy]

I've been obsessed with traffic signals and I've lived in suburban Chicagoland all my life.  It seems that road agencies don't really care that much about where the leftmost signal is placed on the mast arm; it seems to be mostly the result of pure chance.  Several mast arm assemblies are delivered to the site, and the engineer and contractor try to figure out from the plans where to place each one.  This sometimes goes according to plan, but all too often, crews have to dodge around aerial lines and underground utilities to make adjustments to the positioning prescribed in the plans.  Sometimes, you'll find a signal mast where the base of the signal had to be moved farther to the left to dodge some utility line, leaving a lot of extra mast-arm hanging out to the left of the leftmost signal head.  Conversely, sometimes the mast arm's base had to be moved farther to the right, away from the pavement, and the leftmost signal head ends up too far to the right,

Overall, I think P-P signals around here are designed so that the 5-section tower lines up with the right edge of the left turn lane, so that it faces the white line separating the turn lane from the thru lanes.  But adjustments in the field will often jerk that 5-section tower's final position to the left or right.  In addition, some engineers value signal head visibility and will put the signals in the center of lanes...while others value saving cost on the mast arm--to get the shortest viable mast arm, they will put all the signals on the right edge of their corresponding lane, so the mast arm can be a little shorter and cheaper.

Recent guidance from road officials and the MUTCD is often interpreted as "put one signal on the mast arm for each lane on the approach."  Thus, new signals will often have a 5-section tower for each turn lane (so long as there are no dual turn lanes), and a 3-section head for each thru lane.  Some designs based on this tenet put a signal head in the center of each approach lane, but still, I'll see signals in Illinois with one signal head per lane, where every head faces a lane line (i.e. the tower with the left turn arrow faces the solid white line on the right edge of the left turn lane, and every other head is spaced 12 feet out to the right).

In general, different engineers and designers will differ in their opinion on how this should be done.  I started out working in design right out of college, and a coworker had my newbie ass designing a signal somewhere in Naperville.  He told me I should put one signal head on the mast arm for every approach lane.  The approach lanes consisted of two thru lanes and a left turn lane (right turn option from right lane).  Given that each lane had its own signal head, I assumed that I could center the signal positions with respect to each lane, since no lanes needed to share a signal head.  After turning in my work, the guy I reported to scrapped my design and redid the design himself (sadface), putting each signal head 5-6 feet to the right of what I proposed, so they faced the lane lines...all to save the cost of 5-6 feet's worth of mast arm.

[ran4sh]

I've always wondered why some people interpret the 5-section signal to be a left-turn signal when it is clearly a shared signal. If it were a left turn signal, then during the left green arrow phase it wouldn't display a red circle/ball.

[Revive 755]

The overhead signal, ideally, would be mounted in the center of the approach. Left + through lane = between the two lanes; left + two through lanes = directly over left through lane (example of what I like in Skokie, IL)

I don't care for that design - too easy to loose track of the signal while watching oncoming traffic for a gap to turn during the circular green.  That design is even worse when the left turn lane is separated from the adjacent through lane.

[jeffandnicole]

The overhead signal, ideally, would be mounted in the center of the approach. Left + through lane = between the two lanes; left + two through lanes = directly over left through lane (example of what I like in Skokie, IL)

I don't care for that design - too easy to loose track of the signal while watching oncoming traffic for a gap to turn during the circular green.  That design is even worse when the left turn lane is separated from the adjacent through lane.

This design is ultra-common, and there are two signals in eyesight.  Much better than states and areas were only one signal is used for permissive left turns.

[jakeroot]

The overhead signal, ideally, would be mounted in the center of the approach. Left + through lane = between the two lanes; left + two through lanes = directly over left through lane (example of what I like in Skokie, IL)

I don't care for that design - too easy to loose track of the signal while watching oncoming traffic for a gap to turn during the circular green.  That design is even worse when the left turn lane is separated from the adjacent through lane.

The placement of the supplemental left turn signal on the left side of the intersection, in my opinion, greatly negates the need for an overhead left turn signal directly over or near the left turn lane, although I certainly wouldn't want it any further away than where it is in that Skokie example.

As long as every signal is within the line of sight on the approach, I actually find left turn signals directly over the left turn lane (or even slightly offset to the right or left) to not be very helpful as they are very easily blocked. For someone in the left turn lanes of that intersection in Skokie, the left turn signals should be very easily visible even with a dozen cars in front of you.

[wanderer2575]

That is correct, the intent in the 2009 MUTCD is for FYA or protected-only signals to be above or in front of left-turn lanes.

Doghouses/5-section signals are recommended to be positioned above the line that separates the left-turn lane from the thru lane. This also emphasizes that it is a shared left/thru signal rather than a signal that only applies to left-turning traffic.
recommended.

But that shouldn't be necessary IF there is an overhead signal for each lane.  Here's one of several near me that drive me nuts:  Three lanes (left, thru, and right) and three signals, but the doghouse on the right is between the lanes.  Which also shoves the middle thru-only signal too far to the left.
https://goo.gl/maps/sLd1gNxQgn57CrMu8

[jakeroot]

That is correct, the intent in the 2009 MUTCD is for FYA or protected-only signals to be above or in front of left-turn lanes.

Doghouses/5-section signals are recommended to be positioned above the line that separates the left-turn lane from the thru lane. This also emphasizes that it is a shared left/thru signal rather than a signal that only applies to left-turning traffic.
recommended.

But that shouldn't be necessary IF there is an overhead signal for each lane.  Here's one of several near me that drive me nuts:  Three lanes (left, thru, and right) and three signals, but the doghouse on the right is between the lanes.  Which also shoves the middle thru-only signal too far to the left.
https://goo.gl/maps/sLd1gNxQgn57CrMu8

This is the result when agencies do not use post-mounted signals. In a perfect world, there would never be any more overhead signals than number of approach lanes. For a two lane approach with dedicated left turn signal, the second through signal would be on the right mast or pole (example in Auburn, WA), greatly spreading out the signals and improving visibility in the process.

[wanderer2575]

That is correct, the intent in the 2009 MUTCD is for FYA or protected-only signals to be above or in front of left-turn lanes.

Doghouses/5-section signals are recommended to be positioned above the line that separates the left-turn lane from the thru lane. This also emphasizes that it is a shared left/thru signal rather than a signal that only applies to left-turning traffic.
recommended.

But that shouldn't be necessary IF there is an overhead signal for each lane.  Here's one of several near me that drive me nuts:  Three lanes (left, thru, and right) and three signals, but the doghouse on the right is between the lanes.  Which also shoves the middle thru-only signal too far to the left.
https://goo.gl/maps/sLd1gNxQgn57CrMu8

This is the result when agencies do not use post-mounted signals. In a perfect world, there would never be any more overhead signals than number of approach lanes. For a two lane approach with dedicated left turn signal, the second through signal would be on the right mast or pole (example in Auburn, WA), greatly spreading out the signals and improving visibility in the process.

You misunderstand.  There are not more overhead signals than there are approach lanes in my example.  There are three approach lanes (left turn, thru, and right turn -- spin the streetview around 180 degrees) and three signals.  In this case, I think one signal should be centered over each lane.  This can be done with the overheads; post mounting is irrelevant. 

In cases where there are more approach lanes than there are signals, I agree with spreading the signals and putting the doghouse over the divider between lanes.

[1995hoo]

I selected "between the left-turn lane and the left thru lane," such as here (this has been replaced by a flashing yellow arrow), although I would apply the same logic of "between turn lane and thru lane" to a doghouse signal positioned for right-turning traffic, such as going the other way at that same intersection (that right-turn doghouse is still there, but the left-turn signal has been replaced by a flashing yellow arrow).

I could see someone validly objecting to the standalone middle signal in that second Street View link because there are two thru lanes there yet there were three thru signals. The removal of the left-turn doghouse resolved that issue.


(Edited because I misspelled "URL" in one of the tags)

[jakeroot]

That is correct, the intent in the 2009 MUTCD is for FYA or protected-only signals to be above or in front of left-turn lanes.

Doghouses/5-section signals are recommended to be positioned above the line that separates the left-turn lane from the thru lane. This also emphasizes that it is a shared left/thru signal rather than a signal that only applies to left-turning traffic.
recommended.

But that shouldn't be necessary IF there is an overhead signal for each lane.  Here's one of several near me that drive me nuts:  Three lanes (left, thru, and right) and three signals, but the doghouse on the right is between the lanes.  Which also shoves the middle thru-only signal too far to the left.
https://goo.gl/maps/sLd1gNxQgn57CrMu8

This is the result when agencies do not use post-mounted signals. In a perfect world, there would never be any more overhead signals than number of approach lanes. For a two lane approach with dedicated left turn signal, the second through signal would be on the right mast or pole (example in Auburn, WA), greatly spreading out the signals and improving visibility in the process.

You misunderstand.  There are not more overhead signals than there are approach lanes in my example.  There are three approach lanes (left turn, thru, and right turn -- spin the streetview around 180 degrees) and three signals.  In this case, I think one signal should be centered over each lane.  This can be done with the overheads; post mounting is irrelevant. 

In cases where there are more approach lanes than there are signals, I agree with spreading the signals and putting the doghouse over the divider between lanes.

100% agree, my bad for missing that! In these situations, there's no reason the right-turn 5-section signal should not be placed directly in front of the right turn lane. Even then, I suppose it could be off on the right mast or post mounted, but there is definitely no MUTCD rule against 5-section signals being mounted in front of a right turn lane (only for left turn lanes — but then who can blame agencies for being confused by that?).

Your post reminds me a lot of signals I see here in parts of WA and OR, where flashing yellow arrow signals are very common. Every signal is bunched together overhead, barely eight feet apart (if that), and all equally invisible with even a single tall vehicle directly ahead or when bright sun is behind the signals.

[paulthemapguy]

I've always wondered why some people interpret the 5-section signal to be a left-turn signal when it is clearly a shared signal. If it were a left turn signal, then during the left green arrow phase it wouldn't display a red circle/ball.

That's a good thought.  If there are enough three-section thru signals to go around, I'm okay with having the 5-section heads centered to face the turn lane.  But if not, an intermediate position is nice so that it's "shared" between the turn lane and leftmost thru lane.  I didn't answer the poll with a catch-all preference, because based on the number of three-section thru signals, I might prefer either of two options.

[ran4sh]

I'm okay with having the 5-section heads are centered to face the turn lane.

That makes sense if the left turn phase had only the green arrow and not the red circle. With the red circle, it's clear that it's meant for thru traffic as well.

[roadfro]

I'm okay with having the 5-section heads are centered to face the turn lane.

That makes sense if the left turn phase had only the green arrow and not the red circle. With the red circle, it's clear that it's meant for thru traffic as well.

Unless you're using louvers to shield the 5-section head indications from through traffic, then you could have it as a dedicated left turn signal head. Las Vegas and a few other jurisdictions ran this at select locations where they wanted to do time-of-day PPLT operation (i.e. not run permissive turns during rush hour). But this was prior to the MUTCD adoption of the FYA, and you'd be better served to install an FYA to accomplish something like that nowadays.

[ran4sh]

I've never encountered "Dallas phasing" (it wasn't used anywhere in Georgia or the Carolinas, so I've never seen it), but my experience with louvers is that they don't really fully block the signal indications from being visible to adjacent lanes. A programmed-visibility type of signal is more effective at ensuring that adjacent lanes don't see indications that aren't intended for them.

[paulthemapguy]

I'm okay with having the 5-section heads are centered to face the turn lane.

That makes sense if the left turn phase had only the green arrow and not the red circle. With the red circle, it's clear that it's meant for thru traffic as well.

My position is basically: if the thru traffic is already adequately served by other signal heads, then the traffic in the turn lane doesn't need to share its signal head with them.

[ran4sh]

But I'm referring to what the 5-section signal is actually indicating. If it indicates a red circle with a left green arrow, then that makes it a thru signal even if "thru traffic is already adequately served by other signal heads".

[Hobart]

But I'm referring to what the 5-section signal is actually indicating. If it indicates a red circle with a left green arrow, then that makes it a thru signal even if "thru traffic is already adequately served by other signal heads".

First, it is worth mentioning that the 5-section signal is actually a left turn signal in its own right, it just happens to share more than half of its indications with the thru direction. The left turn lane interprets these indications differently, yielding to oncoming traffic on the green ball rather than going like the thru traffic. This is also shown in Dallas phasing, where the 5-section heads operate completely independently than the thru heads. It can be used as a thru head, sure, but it's main purpose is to be a left turn head with left turn arrows.

Second, if the left turn lane is relatively far from the thru lanes, it's more important that the left turn lane can actually see the signal with the arrows than making it so "the thru traffic gets the thru signal".

[ran4sh]

The point is, if it were a left turn signal, then during a phase where left turn traffic can go while straight through has to stop, there would be a green arrow and no red circle.

[mrsman]

The point is, if it were a left turn signal, then during a phase where left turn traffic can go while straight through has to stop, there would be a green arrow and no red circle.

Correct.  The 5-section signal head is for both thru and left functions.  But before the FYA was defined, there was no set indication that ONLY meant left turn yield to oncoming traffic.  The arrow indications indicated a protected left, a green ball indicated that parallel thru traffic had the right of way and a red indication indicated that another direction had the right of way.  On a 5-section dispaly, an indication for the permitted left turn was both a green ball and no arrow being displayed.

In a general sense, the 5-section head is a hybrid display, thus it can be displayed on the lane line between the thru lane and the left turn lane.  Both lanes will watch the indication.  Dallas phasing is a big exception, because the orb signals on the 5-section head do not match the other orb signals - so in that case the full 5-section head is a left turn indication.

In the 1960s -1990s standards for CA signals, generally n-1 signals would be displayed.  A very typical set up with a 5-section display will have a 5-section head on the left corner, a 5-section head on the mast arm, and a 3-section head on the right corner.  This would be the indication, even on relatively wide streets. 

Here's an example, Olympic at La Brea in Los Angeles:

https://www.google.com/maps/@34.0572351,-118.3458049,3a,37.5y,268.06h,90.48t/data=!3m6!1e1!3m4!1sOW8pi4sLsondkc4Z0O8NRA!2e0!7i16384!8i8192!5m1!1e2

If the 5-section head were only for the left turners, then that would mean that all of the thru traffic would be completely reliant on the right-hand signal.  But that's not true, as the right hand signal would generally be hard to see in all but the right lane.  Olympic is three lanes in each direction with a left turn lane.  Having grown up in this general area, I can tell you that most thru traffic absolutely uses the single overhead signal as its dominant indication, unless the view of the signal head were blocked by a large vehicle.