Traffic signal

[STLmapboy]

Utah has 11 freeway-under SPUIs. All but one take the "let's put all the lights on one massive monotube in the middle"  approach. The only one that doesn't is the newest one on Bangerter at 114th South, and it is fascinating because it's actually possible for thru traffic on 114th to not realize they're driving through an interchange if they aren't paying attention.

Um...I sure as hell wouldn't miss that, not with the mast arm and traffic lights with reflective borders.

[mapman]

Here's the signal structure (literally) at the SPUI at CA 87 and Taylor Street in San Jose, CA.

https://goo.gl/maps/4nnAfYhUYT5rUtkQA

(Oh the days when SPUIs were the state-of-the-art interchanges...)

[SkyPesos]

Utah has 11 freeway-under SPUIs. All but one take the "let's put all the lights on one massive monotube in the middle"  approach. The only one that doesn't is the newest one on Bangerter at 114th South, and it is fascinating because it's actually possible for thru traffic on 114th to not realize they're driving through an interchange if they aren't paying attention. It's damn near impossible to miss the interchange on all the others.

I don't see how drivers would miss that one, as it looks like every other traffic signal before and after it on the same road. Maybe because it's not a fat monotube like the others in that area? But at the same time, I've seen 2 drivers (1 left turn, 1 straight) go through a red light on MO 340 at the SPUI with I-270.

[roadman65]

This signal here in Beaufort, SC at SC 170's east end has only one straight through signal head as the others around it are actually either right or left turn signals.  Though, it represents the movement in front of each individual head, it still kind of seems odd though that the one straight through lane gets only one signal head when the MUTCD requires two for that movement.

https://www.flickr.com/photos/54480415@N08/50898386867/in/dateposted-public/

[SkyPesos]

This signal here in Beaufort, SC at SC 170's east end has only one straight through signal head as the others around it are actually either right or left turn signals.  Though, it represents the movement in front of each individual head, it still kind of seems odd though that the one straight through lane gets only one signal head when the MUTCD requires two for that movement.

https://www.flickr.com/photos/54480415@N08/50898386867/in/dateposted-public/

As someone that is used to signal layouts in MO, the fact that the straight movement is represented with a ball instead of an arrow seems off to me for some reason. Not that this is an issue.

And I thought that the one straight movement getting one signal head makes sense, as there's only 1 lane for that movement, and it's an option lane.

[US 89]

Um...I sure as hell wouldn't miss that, not with the mast arm and traffic lights with reflective borders.

I don't see how drivers would miss that one, as it looks like every other traffic signal before and after it on the same road. Maybe because it's not a fat monotube like the others in that area?

When I said "easy to miss", I wasn't talking about missing the red light...I was more referring to how it's not immediately obvious that you're about to drive over a freeway.

Compare that interchange with a more conventional Utah SPUI and you'll see what I'm getting at. The new one is a lot more compact and lacks the characteristic monotube.

[jakeroot]

And I thought that the one straight movement getting one signal head makes sense, as there's only 1 lane for that movement, and it's an option lane.

MUTCD requires at least two through signals (aka green orbs or green up arrows) for any through movement. If no through movement exists, you must have two signals for the important movement.

[jakeroot]

When I said "easy to miss", I wasn't talking about missing the red light...I was more referring to how it's not immediately obvious that you're about to drive over a freeway.

Compare that interchange with a more conventional Utah SPUI and you'll see what I'm getting at. The new one is a lot more compact and lacks the characteristic monotube.

Another sign would certainly be the lack of any apparent rise or descent in the roadway to clear the freeway at the Bangerter/114 example. Your "more conventional" example shows a very clear rise which is often a sign of a major roadway passing beneath (no signal controls likely indicate a railway crossing in that instance, however).

Side-note: Utah has excellent signal location tactics at SPUIs; shame that doesn't extend to other intersections.

[SkyPesos]

Um...I sure as hell wouldn't miss that, not with the mast arm and traffic lights with reflective borders.

I don't see how drivers would miss that one, as it looks like every other traffic signal before and after it on the same road. Maybe because it's not a fat monotube like the others in that area?

When I said "easy to miss", I wasn't talking about missing the red light...I was more referring to how it's not immediately obvious that you're about to drive over a freeway.

Compare that interchange with a more conventional Utah SPUI and you'll see what I'm getting at. The new one is a lot more compact and lacks the characteristic monotube.

That might be partly because there's no overhead signage for UT 154 prior to the intersection. I can see myself missing the entrance as a new driver in the area without a GPS without either overhead signage or the standard monotube. Here's another view of the I-270 and MO 340 SPUI I mentioned a lot earlier. Without the overhead signage on MO 340 to I-270, this one would probably also be easy to miss. The median mast arm poles may be a give away, but a lot of intersections on MO 340 have their mast arm supported in the median (this is something that Missouri loves to do that I don't really see in other states). A monotube or truss gantry for the signals may help drivers not miss their freeway entrance from a SPUI, but so can overhead signage.

[SignBridge]

This signal here in Beaufort, SC at SC 170's east end has only one straight through signal head as the others around it are actually either right or left turn signals.  Though, it represents the movement in front of each individual head, it still kind of seems odd though that the one straight through lane gets only one signal head when the MUTCD requires two for that movement.

https://www.flickr.com/photos/54480415@N08/50898386867/in/dateposted-public/

As someone that is used to signal layouts in MO, the fact that the straight movement is represented with a ball instead of an arrow seems off to me for some reason. Not that this is an issue.

And I thought that the one straight movement getting one signal head makes sense, as there's only 1 lane for that movement, and it's an option lane.

Interesting design problem. The Manual does require two circular greens for the thru movement even if it's only one lane. But I have to agree in this one case, it might be misleading to put a circular green in any of the other heads because only that one lane is a thru lane. So how do you meet the requirement without misleading drivers re: lane assignments?

[jakeroot]

Interesting design problem. The Manual does require two circular greens for the thru movement even if it's only one lane. But I have to agree in this one case, it might be misleading to put a circular green in any of the other heads because only that one lane is a thru lane. So how do you meet the requirement without misleading drivers re: lane assignments?

Weirdly, it's a design issue created by the FHWA themselves. By suggesting signal-per-lane strategies be the end-all design philosophy, agencies are left with shrugged shoulders when you have turn lanes on either side of a single through lane and those turn lanes use dedicated signals, as is often the case with double right turns.

One solution for the above signal is to delete the far left signal, and duplicate the second signal (green orb + green left arrow) on the far left mast. This gives you double left turn green arrows, double through signals as required, and double right turn signals.

Alternatively, delete the left-most right turn signal, placing it on the right-side mast, and replace that signal with a RYG orb signal.

Another option might be to dump the right turn signals in favor of 5-section signals.

[SkyPesos]

Interesting design problem. The Manual does require two circular greens for the thru movement even if it's only one lane. But I have to agree in this one case, it might be misleading to put a circular green in any of the other heads because only that one lane is a thru lane. So how do you meet the requirement without misleading drivers re: lane assignments?

Weirdly, it's a design issue created by the FHWA themselves. By suggesting signal-per-lane strategies be the end-all design philosophy, agencies are left with shrugged shoulders when you have turn lanes on either side of a single through lane and those turn lanes use dedicated signals, as is often the case with double right turns.

One solution for the above signal is to delete the far left signal, and duplicate the second signal (green orb + green left arrow) on the far left mast. This gives you double left turn green arrows, double through signals as required, and double right turn signals.

Alternatively, delete the left-most right turn signal, placing it on the right-side mast, and replace that signal with a RYG orb signal.

Sometimes, I wonder if 1 signal per direction, like what I see with most signals Canada and China and probably many other countries, is enough opposed to the current 1 signal per lane...

[jakeroot]

Sometimes, I wonder if 1 signal per direction, like what I see with most signals Canada and China and probably many other countries, is enough opposed of the current 1 signal per lane...

Definitely not, for numerous reasons. Visibility of signals is hugely important, as is redundancy in the case of electrical issues or burn-out.

Canada has the same rules as the US, requiring two through signals for every approach. China is pretty much alone, and for good reason: their signals are not sufficient. Judging by their crash rate, China is the last place we should be inspired by...

[SkyPesos]

Sometimes, I wonder if 1 signal per direction, like what I see with most signals Canada and China and probably many other countries, is enough opposed of the current 1 signal per lane...

Definitely not, for numerous reasons. Visibility of signals is hugely important, as is redundancy in the case of electrical issues or burn-out.

Canada has the same rules as the US, requiring two through signals for every approach. China is pretty much alone, and for good reason: their signals are not sufficient. Judging by their crash rate, China is the last place we should be inspired by...

There's issues with China's roads and drivers besides their signals with their higher crash rate, but that's another topic. Something I'll note is that a lot of their freeway to surface interchanges in China are like SPUIs, and sometimes, the traffic signals are easy to miss.

For Canada, I forgot to count the green bulb on the 4 section signals in Ontario, so yea that makes it 2 after counting it. Does the US MUTCD say anything about needing 3 through signals for a 3 lane road, or is that up to the state? Missouri, for the most part, have 3 through signals for 3 lane roads in one direction, but Ohio sometimes doesn't, sticking to the usual 2. I see that Ontario at least only have 2 through signals even for a 3 lane.

[SignBridge]

Interesting design problem. The Manual does require two circular greens for the thru movement even if it's only one lane. But I have to agree in this one case, it might be misleading to put a circular green in any of the other heads because only that one lane is a thru lane. So how do you meet the requirement without misleading drivers re: lane assignments?

Weirdly, it's a design issue created by the FHWA themselves. By suggesting signal-per-lane strategies be the end-all design philosophy, agencies are left with shrugged shoulders when you have turn lanes on either side of a single through lane and those turn lanes use dedicated signals, as is often the case with double right turns.

One solution for the above signal is to delete the far left signal, and duplicate the second signal (green orb + green left arrow) on the far left mast. This gives you double left turn green arrows, double through signals as required, and double right turn signals.

Alternatively, delete the left-most right turn signal, placing it on the right-side mast, and replace that signal with a RYG orb signal.

Another option might be to dump the right turn signals in favor of 5-section signals.

Jakeroot, your post is very well reasoned. The FHWA shot themselves in the foot when they changed that rule in the 2009 Manual I believe. Prior to that the requirement was for a minimum of two signals for the predominant route, not necessarily the thru route. That might have worked better here. But your solution of putting one of the right or left turn signals on a mast and replacing the overhead with a green ball might work very well.

[fwydriver405]

This signal here in Beaufort, SC at SC 170's east end has only one straight through signal head as the others around it are actually either right or left turn signals.  Though, it represents the movement in front of each individual head, it still kind of seems odd though that the one straight through lane gets only one signal head when the MUTCD requires two for that movement.

https://www.flickr.com/photos/54480415@N08/50898386867/in/dateposted-public/

I've always had this question for a while now but never know how to ask it since I was curious about what signals were best for this kind of application, assuming those right turns are protected only and have no pedestrian conflict. There are four intersections in Maine, 2 in Scarborough, 1 in Biddeford, and 1 in Bangor that are like this:

One solution for the above signal is to delete the far left signal, and duplicate the second signal (green orb + green left arrow) on the far left mast. This gives you double left turn green arrows, double through signals as required, and double right turn signals.

So something like this intersection in Biddeford?

Alternatively, delete the left-most right turn signal, placing it on the right-side mast, and replace that signal with a RYG orb signal.

This example from Portsmouth NH only has 2 lanes (left/thru, right), but if there was a second right turn lane in addition to what is present, something like this or this?

Another option might be to dump the right turn signals in favor of 5-section signals.

So something like the ME Turnpike / Haigis Pkwy and Payne Rd intersection in Scarborough, or this one in Manchester CT? (Edit 3-Aug-22. For Scarborough, as part of the Scarborough Downs project, this approach has been reconfigured from L-T-R-R to L-L-T-R, eliminating the issue mentioned above)

The other intersections in question are US 1 / Payne Rd in Scarborough (only one thru head) and I-95 / Stillwater Ave in Bangor (there used to be a doghouse between the three section signals as shown here as of 2007).

[jakeroot]

I've always had this question for a while now but never know how to ask it since I was curious about what signals were best for this kind of application, assuming those right turns are protected only and have no pedestrian conflict. There are four intersections in Maine, 2 in Scarborough, 1 in Biddeford, and 1 in Bangor that are like this:

One solution for the above signal is to delete the far left signal, and duplicate the second signal (green orb + green left arrow) on the far left mast. This gives you double left turn green arrows, double through signals as required, and double right turn signals.

So something like this intersection in Biddeford?

Alternatively, delete the left-most right turn signal, placing it on the right-side mast, and replace that signal with a RYG orb signal.

This example from Portsmouth NH only has 2 lanes (left/thru, right), but if there was a second right turn lane in addition to what is present, something like this or this?

Another option might be to dump the right turn signals in favor of 5-section signals.

So something like the ME Turnpike / Haigis Pkwy and Payne Rd intersection in Scarborough, or this one in Manchester CT?

The other intersections in question are US 1 / Payne Rd in Scarborough (only one thru head) and I-95 / Stillwater Ave in Bangor (there used to be a doghouse between the three section signals as shown here as of 2007).

Sorry to quote the whole post. Easier than responding bit-by-bit.

To answer succinctly: yes, those examples are all ways that the South Carolina intersection could be improved. The intersection shown above is not compliant with the MUTCD despite the numerous ways that it could have otherwise been installed. I understand the general confusion around signal-per-lane strategies and signal-head requirements, but there are ways to approach the problem while still being compliant. You just have to be creative.

In particular, I would say that I'm quite a fan of the install along Hale Road in Manchester, CT. It's not a perfect match for this intersection, but I think it's a great way to approach the problem, even if the right turn never has to yield. I am personally not a fan of using right red arrows if RTOR is to be permitted, as traffic sometimes falsely assumes that it's illegal. Certainly it is illegal in some places...but if it isn't, don't trick drivers into thinking it is! Just use a darn "NTOR" sign.

As for examples from my area:

• Good example of a split-phased approach with the 4-section green arrow + green ball both overhead and on left in Kent, WA;
• Approach with a double left and single right in Lakewood, WA. It used to be permissive with just a couple overhead green orbs;
• This exit from a shopping center in Tacoma has double turns in both directions but only a single shared through lane;
• Good example of combining a double right turn's 5-section towers with the through signal in Federal Way, WA (right turn has a crossing phase, necessitating green orbs);
• Moving to BC, this approach in Downtown Vancouver has a double right adjacent to a single through lane; all signals have a green orb and there is no right-turn overlap;
• As well, this double right turn in North Vancouver (same as above but w/ left turns) uses 4-section bimodal right turn signals; as in above example, the other through signal is on the left mast.

So yeah, there's ways to solve the South Carolina intersection, you just have to think a bit more creatively!

edit: "Florida intersection"..? Ay qué rico...

[jakeroot]

As an example of how I might fix it (SC-170 @ Boundary St, Beaufort), I'd go with a more typically-Californian approach. The near-side signal is especially important with the curve.



edit: fixed some layering issues.

[SkyPesos]

With the minimum 2 green bulbs or arrows for the straight movement, I'm guessing this one at the NB I-71 ramp to Mason-Montgomery Rd also violates the MUTCD, despite that left turns is the primary movement here. Could be easily fixed by adding a fourth signal with a green ball between the second left signal and the doghouse. Note that Ohio normally doesn't place signals on the vertical beams.

[DrSmith]

This one doesn't even try, only on each and it's new
https://goo.gl/maps/gBBStpZo2A5k9sD19

[Amtrakprod]

As an example of how I might fix it (SC-170 @ Boundary St, Beaufort), I'd go with a more typically-Californian approach. The near-side signal is especially important with the curve.



edit: fixed some layering issues.

How'd you add traffic lights into street mix?


iPhone

[fwydriver405]

This one doesn't even try, only on each and it's new
https://goo.gl/maps/gBBStpZo2A5k9sD19

I wonder if the contractor thought they were going to install a shared, "yield on green" 4-section bimodal signal rather than a(n) FYA... because that signal configuration would be OK if the FYA was just a shared, "yield on green" 4-section bimodal signal.

[jakeroot]

How'd you add traffic lights into street mix?

I made the street, then downloaded it with a transparent background. I added the signals myself using Illustrator, leaving the streetmix image in the foreground.

[fwydriver405]

Alternatively, delete the left-most right turn signal, placing it on the right-side mast, and replace that signal with a RYG orb signal.

This example from Portsmouth NH only has 2 lanes (left/thru, right), but if there was a second right turn lane in addition to what is present, something like this or this?

Actually, while looking for a signal for another thread, I think this signal in Salem, NH better fits the conditions above.

[hotdogPi]

Alternatively, delete the left-most right turn signal, placing it on the right-side mast, and replace that signal with a RYG orb signal.

This example from Portsmouth NH only has 2 lanes (left/thru, right), but if there was a second right turn lane in addition to what is present, something like this or this?

Actually, while looking for a signal for another thread, I think this signal in Salem, NH better fits the conditions above.

What is the point of the "no turn on red arrow" sign? It's a left turn, and it's not the type of intersection where someone would expect a left on red.