Traffic signal

[MNHighwayMan]

The video I promised:

[intelati49]

Just wanted to jump in and share this traffic signal photo from the entrance to Arches NP in Moab, UT.  It's a combination of a constant-burning green and an FYA, which I hadn't seen before.  The photo is taken facing south. Left-turning traffic from the left ends up on a left-hand merge ramp that takes up the center lane until it dissipates farther ahead.


UT-US191-ArchesS by Paul Drives, on Flickr

Never seen these in action. I'm interested in the safety/crash rate of the turning movements.

[jakeroot]

I think this may be the thickest mast arm I've ever encountered:

212 St @ Hwy 9 east of Maltby, Washington:

[jakeroot]

Just wanted to jump in and share this traffic signal photo from the entrance to Arches NP in Moab, UT.  It's a combination of a constant-burning green and an FYA, which I hadn't seen before.  The photo is taken facing south. Left-turning traffic from the left ends up on a left-hand merge ramp that takes up the center lane until it dissipates farther ahead.

https://c1.staticflickr.com/5/4168/34312408082_8007978a12_c.jpg

Never seen these in action. I'm interested in the safety/crash rate of the turning movements.

Which is it that you haven't seen:

1) a seagull intersection with permissive phasing; or
2) a seagull intersection with a flashing yellow arrow; or
3) this particular signal?

As far as the safety/crash rate, I doubt it's any worse (at this particular intersection) than it was before. It replaced a free left w/o a signal at all.

[plain]

I think this may be the thickest mast arm I've ever encountered:

212 St @ Hwy 9 east of Maltby, Washington:

Oh wow... that's past fat... that's all out obese. I saw a couple of half spans around here that I thought was fat but not quite like that

US 60 (Midlothian Tpk just SW of Richmond)
https://goo.gl/maps/JSBm9AEZdNB2

US 250 (Broad St, NW of Richmond)
https://goo.gl/maps/agwwKropRKF2

[SignBridge]

Wow, seven heads on the same arm on Midlothian Turnpike. That must be a record. And the arm even extends beyond the last head. Must be like maybe a 60 foot long arm?

[MNHighwayMan]

If we're going for the most heads on a single mast arm, this signal in Des Moines has eight heads on one arm (though they're for three directions of travel).

[cl94]

If we're going for the most heads on a single mast arm, this signal in Des Moines has eight heads on one arm (though they're for three directions of travel).

There are a ton of 4-way intersections around here with all 8 heads on one arm. That doesn't impress me. I can't think of any with more than 8 heads, though. THAT would be interesting to see.

[MNHighwayMan]

Given that the signal on the opposite corner has one with seven heads, perhaps they should've just gone for gold and just used one massive arm that carries all fifteen heads.

[plain]

Wow, seven heads on the same arm on Midlothian Turnpike. That must be a record. And the arm even extends beyond the last head. Must be like maybe a 60 foot long arm?

Not sure the length but sounds about right.
The city of Hampton also squeezed 7 on this one on US 258 Mercury Blvd

https://goo.gl/maps/ttSSauhXH4C2

[roadfro]

Wow, seven heads on the same arm on Midlothian Turnpike. That must be a record. And the arm even extends beyond the last head. Must be like maybe a 60 foot long arm?

If you assume one signal head centered over each lane, and assume each lane is 12 feet wide, that mast arm would have to be at least 84 feet long. It's probably closer to 90 or even 100 feet, when you consider the mast pole setback from curb and that the arm extends past the last signal.

[jakeroot]

Wow, seven heads on the same arm on Midlothian Turnpike. That must be a record. And the arm even extends beyond the last head. Must be like maybe a 60 foot long arm?

If you assume one signal head centered over each lane, and assume each lane is 12 feet wide, that mast arm would have to be at least 84 feet long. It's probably closer to 90 or even 100 feet, when you consider the mast pole setback from curb and that the arm extends past the last signal.

The arm that extends past the last signal wouldn't really count. The 84-feet measurement was based on the mast arm being at least as long as the number of lanes (i.e. right edge of roadway to left edge of roadway). First signal to last signal probably around 72-74 feet. The bit that would make it longer than 84 feet would be the distance between the edge of the road and mast arm mount. I'm thinking the total length is close to around 90-92 feet.

[TheArkansasRoadgeek]

What is with spacing of traffic lights? Like, they wouldn't have to make the mast so long if they snuggled them in closer to each other.

[plain]

What is with spacing of traffic lights? Like, they wouldn't have to make the mast so long if they snuggled them in closer to each other.

Many jurisdictions place the signals so there are one over each lane.

[jakeroot]

What is with spacing of traffic lights? Like, they wouldn't have to make the mast so long if they snuggled them in closer to each other.

You wouldn't want them any closer together. Most states have a minimum distance allowed between signals. One per lane is generally a minimum separation.

VA should have mounted one signal over the centerline of the two left turn lanes, and used only three overhead signals: one between the #1 and #2 lanes, one centered above the #3 lane, and one between the #4 and #5 lanes. Then, add secondary signals on the left and right masts. They have seven overhead signals, yet none are visible if a truck is in front of you. That's crappy signalization in my book, even if it's VA standards.

[plain]

What is with spacing of traffic lights? Like, they wouldn't have to make the mast so long if they snuggled them in closer to each other.

You wouldn't want them any closer together. Most states have a minimum distance allowed between signals. One per lane is generally a minimum separation.

VA should have mounted one signal over the centerline of the two left turn lanes, and used only three overhead signals: one between the #1 and #2 lanes, one centered above the #3 lane, and one between the #4 and #5 lanes. Then, add secondary signals on the left and right masts. They have five overhead signals, yet none are visible if a truck is in front of you. That's crappy signalization in my book, even if it's VA standards.

Hampton does this... well sort of...
W Mercury Blvd
https://goo.gl/maps/LecxCwujeV52

[jakeroot]

What is with spacing of traffic lights? Like, they wouldn't have to make the mast so long if they snuggled them in closer to each other.

You wouldn't want them any closer together. Most states have a minimum distance allowed between signals. One per lane is generally a minimum separation.

VA should have mounted one signal over the centerline of the two left turn lanes, and used only three overhead signals: one between the #1 and #2 lanes, one centered above the #3 lane, and one between the #4 and #5 lanes. Then, add secondary signals on the left and right masts. They have seven overhead signals, yet none are visible if a truck is in front of you. That's crappy signalization in my book, even if it's VA standards.

Hampton does this... well sort of...
W Mercury Blvd
https://goo.gl/maps/LecxCwujeV52

Getting there....something like this would be superior (from my Imgur archives, Federal Way, WA)

[Big John]

What is with spacing of traffic lights? Like, they wouldn't have to make the mast so long if they snuggled them in closer to each other.

You wouldn't want them any closer together. Most states have a minimum distance allowed between signals. One per lane is generally a minimum separation.

MUTCD calls for a 8' minimum between signals performing the same function.

[cl94]

I need to get a picture of this in action, but I spotted something this afternoon. 4th Street (US 4 NB) in Troy, NY. The yellow lens of this signal has "CAUTION" written on it. Nothing on the green or red. I drive through here a couple times a week and just noticed it today.

[SignBridge]

Re: the MUTCD spacing standard, it actually requires a minimum of 8 feet between the two required heads for each approach. There does not seem to be a minimum spacing for all other heads. New York City has some left/right turn heads mounted immediately adjacent to the circular-green heads. I mean just a couple of feet apart. And just to clarify, the measurement is center-of-lens to center-of-lens.

I would prefer a minimum spacing requirement of 12 feet. That is, a lane-width apart. If you've ever seen a mast-arm with 8 ft. spacing between heads, they look too close together. Common in Pennsylvania.

That photo from Federal Way, Washington looks very good and is almost identical to California's standard configuration which I've always liked.

[Ian]

I need to get a picture of this in action, but I spotted something this afternoon. 4th Street (US 4 NB) in Troy, NY. The yellow lens of this signal has "CAUTION" written on it. Nothing on the green or red. I drive through here a couple times a week and just noticed it today.

Neat to see some command lenses still being used. Those are hard to come by in the field nowadays!

[Mdcastle]

So can someone raise the bar and find an Adler lens in use?

[Revive 755]

I would prefer a minimum spacing requirement of 12 feet. That is, a lane-width apart. If you've ever seen a mast-arm with 8 ft. spacing between heads, they look too close together.

A 12 feet minimum wouldn't work if the lanes are less than 12 feet wide.  The 8 foot minimum also helps for signals where two heads are being provided on the mast arm for a single through lane, but both an adjacent left turn lane and adjacent right turn lane are using all-arrow heads.

[cl94]

I would prefer a minimum spacing requirement of 12 feet. That is, a lane-width apart. If you've ever seen a mast-arm with 8 ft. spacing between heads, they look too close together.

A 12 feet minimum wouldn't work if the lanes are less than 12 feet wide.  The 8 foot minimum also helps for signals where two heads are being provided on the mast arm for a single through lane, but both an adjacent left turn lane and adjacent right turn lane are using all-arrow heads.

Yeah, 12 feet wouldn't work here in Troy if you expect each approach to have 2 heads. Most of the streets are too narrow. With the 8 foot requirement, a ton of the narrow one-way streets have the signal heads on opposite sides of the lane. 12 feet would place at least one of them over the parking lanes.

[SignBridge]

In the situation that Revive 755 illustrated, he has a point, but that's a rare scenario. In most cases if you only have a single thru lane the best practice might be one overhead and one far-right pole mounted head.

My objection to 8 ft. spacing is where it's used over two thru lanes and they're both over the left lane. I've seen this a lot in the Philadelphia, Pa. suburbs. In that situation, one head over the center of each 12 ft. lane would be the best practice and would result in 12 ft. spacing and could still be done with 8 or 10 ft. lanes.