US traffic lights that don't have 2 'thru' signals.

[KEK Inc.]

It's a violation of the MUTCD, so it should be rare. 

Here's a couple of signals in the same intersection:
https://goo.gl/maps/kpqYw

https://goo.gl/maps/bzr8R

[UCFKnights]

https://www.google.com/maps/@28.573397,-81.207543,3a,75y,254.56h,86.11t/data=!3m4!1e1!3m2!1sZYXcdS8UmgxKwHXWAWnY_A!2e0

[vdeane]

https://www.google.com/maps/@42.905423,-74.572156,3a,75y,169.71h,92.62t/data=!3m4!1e1!3m2!1sfPW4NNlAhACP42E1xG3j5Q!2e0

[jakeroot]

Does it count if one is an up arrow? Can't remember if the law is two green orbs or, indeed, just two green through signals of any type.

Either way Kek, Seattle has quite a few of these violations. I would post some if I wasn't at work. I seem to remember them being common at freeway off-ramps.

[cl94]

Quite common in older installations maintained by cities/towns/villages, at least in the northeast.

Glens Falls, NY has quite a few and used to have several more. There's this intersection on a city-maintained stretch of NY 9L. The NY 9L approach to the US 9/NY 9L/NY 32 intersection had a single head before the roundabout was built. Actually, if it's a 2-lane road, one head is the norm in Glens Falls unless it's been replaced within the past 10-15 years with external funding. Most of the signals on US 9 and NY 32 have been replaced or always had 2 heads/direction, while the other streets are still mainly single heads.

[Roadrunner75]

Most of the intersections along Washington Street in Hoboken have only a single overhead 4 way signal, with the added bonus that they are usually off to one side from a mast arm on one corner, making them sometimes easy to miss.  Here's a particularly old one:
https://www.google.com/maps?ll=40.737133,-74.030535&spn=0.000004,0.00327&t=m&z=19&layer=c&cbll=40.73723,-74.031019&panoid=CVkcRAU6dDD-jeNqZuAFbA&cbp=12,22.81,,0,-0.06

[Brandon]

I cannot name any intersections in Illinois like this.  IDOT mandates three through signals per direction (an two per turning direction), and has for quite some time.

[KEK Inc.]

https://www.google.com/maps/@28.573397,-81.207543,3a,75y,254.56h,86.11t/data=!3m4!1e1!3m2!1sZYXcdS8UmgxKwHXWAWnY_A!2e0

Actually, I think that's a legal signal.  'Thru' movement could also be turning.  Here's an example of one in Redmond, WA:  https://goo.gl/maps/hx4Kz

In your SV link, what's with the variable regulatory sign to the right of the doghouse?

Does it count if one is an up arrow? Can't remember if the law is two green orbs or, indeed, just two green through signals of any type.

Either way Kek, Seattle has quite a few of these violations. I would post some if I wasn't at work. I seem to remember them being common at freeway off-ramps.

I think that's allowed.  The green up arrow is usually used to emphasize to not turn.  I don't recall violations on any freeway intersections.

[cl94]

https://www.google.com/maps/@28.573397,-81.207543,3a,75y,254.56h,86.11t/data=!3m4!1e1!3m2!1sZYXcdS8UmgxKwHXWAWnY_A!2e0

Actually, I think that's a legal signal.  'Thru' movement could also be turning.  Here's an example of one in Redmond, WA:  https://goo.gl/maps/hx4Kz

Being as "straight" goes into a parking lot, that's perfectly acceptable.

[steviep24]

Brockport, NY still has one.

https://www.google.com/maps/@43.209148,-77.945151,3a,75y,252.91h,83.4t/data=!3m4!1e1!3m2!1sAfo2nbs4VVosBs2h_M-CVQ!2e0!6m1!1e1?hl=en

[jakeroot]

It's Kek's thread, so his rules. But I don't think the old New England single overhead unit should count, since it existed before the dual-through signal rule came about. Personally, I'm more interested in installs from the last twenty years or so.

But again, Kek's thread. So his rules. I'm not thread-jacking, I swear.

[roadman65]

Key West, FL used to have all of its traffic lights that were not on US 1 as single headed either on four way assemblies or on a box wire set up back in the early 1990's.  When I went there in the late 90's they were modified to standards with two through heads.

BTW, on US 1 I assume it had two because FDOT might of not approved of them as all signals in Florida are either county or municipally maintained, so the City of Key West operates all signals even on state maintained US 1.

[Ian]

Montrose, PA

https://goo.gl/maps/haiDz

[jakeroot]

I don't recall violations on any freeway intersections.

Here's one in Federal Way:

http://goo.gl/yL0KCR  >>> Sorry, missed the ground-mounted signal.

And another near Des Moines:

http://goo.gl/hEXcKH

And another two in Seatac:

http://goo.gl/ut2vM4 & http://goo.gl/jCNuWx

One near Issaquah:

http://goo.gl/XbPk34

There's almost certainly more. They are common when there is one left turn lane next to a left and straight lane.

[freebrickproductions]

There are several set-ups around here in Huntsville with only one thru indication.
Many towns with older signals around Alabama still only have one signal per direction, or only one 4-way at the intersection. I'll post some when I get home.

[KEK Inc.]

I don't recall violations on any freeway intersections.

Here's one in Federal Way:

http://goo.gl/yL0KCR  >>> Sorry, missed the ground-mounted signal.

And another near Des Moines:

http://goo.gl/hEXcKH

And another two in Seatac:

http://goo.gl/ut2vM4 & http://goo.gl/jCNuWx

One near Issaquah:

http://goo.gl/XbPk34

There's almost certainly more. They are common when there is one left turn lane next to a left and straight lane.

Those are all legal.  The right signal will always have the protected left, so the thru traffic by design is turning left.  (And rightfully so, since they all have dedicated right-turn bays, and traffic rarely goes straight through freeway intersections.)

[freebrickproductions]

I don't recall violations on any freeway intersections.

Here's one in Federal Way:

http://goo.gl/yL0KCR  >>> Sorry, missed the ground-mounted signal.

And another near Des Moines:

http://goo.gl/hEXcKH

And another two in Seatac:

http://goo.gl/ut2vM4 & http://goo.gl/jCNuWx

One near Issaquah:

http://goo.gl/XbPk34

There's almost certainly more. They are common when there is one left turn lane next to a left and straight lane.

Those are all legal.  The right signal will always have the protected left, so the thru traffic by design is turning left.  (And rightfully so, since they all have dedicated right-turn bays, and traffic rarely goes straight through freeway intersections.)

All of the ones here in Huntsville are like those.

[jakeroot]

I don't recall violations on any freeway intersections.

clipped

Those are all legal.  The right signal will always have the protected left, so the thru traffic by design is turning left.  (And rightfully so, since they all have dedicated right-turn bays, and traffic rarely goes straight through freeway intersections.)

According to this letter between the NCDOT and the FHWA, drivers cannot be expected to interpret which direction of movement is considered major, thus left turns are not considered through (only straight movements are through movements). Basically, each intersection is independent from one another, so despite the fact that continuing straight through any of these intersections would be a bit daft, it is legally the through movement, and should have a second through signal posted.

FWIW, the second SeaTac intersection has a shared left/straight/right lane.

edit: wrong link -- fixed

[jakeroot]

Here's one in Fife, WA. Left lane is left/straight and right lane is right-only. Signal has three red orbs across but the right two signals have green arrows along the bottom. The left signal is a split phase, four head signal, (top to bottom) RB/AB/GB/GA. When all directions have green, you get one left green arrow, one green orb, and two right green arrows.

Hard to follow, but check the street view and you'll see what I mean.

http://goo.gl/1VgpPa

[NYhwyfan]

North Tonawanda, NY has quite a few.

https://www.google.com/maps/@43.025019,-78.867733,3a,75y,346.78h,82.48t/data=!3m4!1e1!3m2!1sgP3-V9NTIHPpf2ndSm_DQA!2e0
https://www.google.com/maps/@43.028849,-78.875092,3a,75y,346.84h,70.18t/data=!3m4!1e1!3m2!1sq1aCW9Qm84aVgMlolCo06A!2e0
https://www.google.com/maps/@43.052328,-78.878611,3a,75y,260.7h,86.34t/data=!3m4!1e1!3m2!1s02VMh0IHbrJDY0yx13GSBw!2e0

[FreewayDan]

There's one along F.M. 1960 north of Houston at Humble-Westfield and Treaschwig Roads:
https://www.google.com/maps/@30.021795,-95.387063,3a,44.9y,213.03h,87.66t/data=!3m4!1e1!3m2!1sXiMsy_M8Vq63dMzItR6L0A!2e0

[jakeroot]

There's one along F.M. 1960 north of Houston at Humble-Westfield and Treaschwig Roads:
https://www.google.com/maps/@30.021795,-95.387063,3a,44.9y,213.03h,87.66t/data=!3m4!1e1!3m2!1sXiMsy_M8Vq63dMzItR6L0A!2e0

Interesting. Not a single green ball to speak of, just the up arrow. I don't think I've ever seen something like that before.

[mrsman]

It's Kek's thread, so his rules. But I don't think the old New England single overhead unit should count, since it existed before the dual-through signal rule came about. Personally, I'm more interested in installs from the last twenty years or so.

But again, Kek's thread. So his rules. I'm not thread-jacking, I swear.

Does the MUTCD (or state law) require a retrofit to meet the two signal rule?  IIRC, the reason for the rule is that there would still be an indication if a light bulb burned out.

[Atomica]

At the very least, it should be a "doghouse" signal, with a yellow left upward arrow as well as a green upward arrow.

[cl94]

It's Kek's thread, so his rules. But I don't think the old New England single overhead unit should count, since it existed before the dual-through signal rule came about. Personally, I'm more interested in installs from the last twenty years or so.

But again, Kek's thread. So his rules. I'm not thread-jacking, I swear.

Does the MUTCD (or state law) require a retrofit to meet the two signal rule?  IIRC, the reason for the rule is that there would still be an indication if a light bulb burned out.

Some (well, most) of these installations are so old that their days are probably numbered. Signals don't last forever and I wouldn't be shocked if many of the single-head installations still around are 30-40 years old. Retrofits at this point would mean full replacement and it's probably coming soon anyway. No point in adding a set of signals if the entire installation will be replaced in the near future.