Traffic signal

[jakeroot]

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.

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.

You could still have a twelve-foot minimum spacing, with exceptions for narrow lanes, etc. The eight-foot minimum has resulted in some terrible signal placement here in Washington (mostly state-maintained signals). You'll have this gigantic mast arm, and the signals are right on top of each other. Spread them out, for God's sake....

There are ways that you could have 8-foot wide lanes, with dedicated left/right/straight signals with only one lane in each direction, and still have at least twelve feet between each signal. I'll mock something up when I get home. Hint: it does involve using the mast to mount signals.

[SignBridge]

Jakeroot, you nailed it with your point about Washington area signals. It seems like some installations they just mount the first signal as far left as possible and then just mount the second one, eight feet to the right because that's the default standard. And it looks terrible.

[MNHighwayMan]

I was driving through Buffalo, MN yesterday, and found this signal design at the very recently reconstructed MN-25/55 junction. My goodness they are fugly (IMO).

[SignBridge]

The truss-type mast-arm with those thick pipes may be ugly, but the spacing and configuration looks about right to me.

[jakeroot]

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.

So here's a quick mock-up of a 12-foot minimum spacing with 8-foot lanes.

There are some obvious caveats...

1) there is no possible way to center the signals above each lane, so the two overhead signals have to be scooted away from each other; and
2) through signals have to have up arrows because the right turn lane points directly at the through signals (which could be confusing).

But overall, I think this works. The situation you describe is extremely unusual, so I don't think maintaining the 8-foot requirement would be necessary just to please these rarities. A 12-foot minimum would work, the agency just has to be a little clever (if for some reason, dedicated L/R/S signals ever became necessary).

[jakeroot]

Here's some examples of how the 8-foot minimum requirement can result in some hideous signal placement. WSDOT is entirely to blame.

The first set of signals (with the unpainted mast arms) were installed in 2016 (167 Valley Freeway @ 8 Street south of Auburn). The last signal (with the black mast arm) was installed in 2013 (Hwy 161 @ Taylor Street, Edgewood).

Don't get me started on the protected lefts in the first set. Flashing yellow arrows would have been great here.



This first signal isn't too bad, because of the secondary, far right post-mounted signal. But the overhead signals are really close together:


The next signal (same junction, opposite off-ramp) also has closely-spaced signals, but no secondary, far-right signal head:


The through signals are fine, but a secondary, mast-mounted signal would have been a good fit here. Not pictured: this approach has two lanes (one straight, one right):


This approach (8 Street EB) is particularly maddening. The left turn originally had a secondary, post-mounted signal on the far left (mounted on the same post where the off-ramp's secondary signal head is located). For some reason, they did away with the secondary signal when they removed the pork-chop island. Most annoyingly, the replaced signal was only added in 2007. What standard changed between '07 and '16 that dictated fewer signals be used?


One intersection over is a signal maintained by the city of Pacific. This signal is unusal in that a five-section signal is mounted over the left turn lane (instead of to the right of it), but it results in good (nigh, great!) spacing. Also odd (though not necessarily related to the signal): the cross-street (Thornton) has a "left turn yield on green" sign, instead of typical "left turn must yield" sign typically used at junctions without left turn arrows (at least here in Washington):


Finally, the last signal, several miles away. Gigantic mast arm, signals right on top of each other :sigh:

[SignBridge]

Good Jakeroot. Your graphic showing the two adjacent heads on the pole for thru and right turns works for me. I've actually seen overhead adjacent-heads like that in New York City.

Interesting photos. Some of them are good examples of 8 ft. spacing being too little of a spread IMO.

[TheArkansasRoadgeek]

Here's some examples of how the 8-foot minimum requirement can result in some hideous signal placement. WSDOT is entirely to blame.

The first set of signals (with the unpainted mast arms) were installed in 2016 (167 Valley Freeway @ 8 Street south of Auburn). The last signal (with the black mast arm) was installed in 2013 (Hwy 161 @ Taylor Street, Edgewood).

Don't get me started on the protected lefts in the first set. Flashing yellow arrows would have been great here.



This first signal isn't too bad, because of the secondary, far right post-mounted signal. But the overhead signals are really close together:


The next signal (same junction, opposite off-ramp) also has closely-spaced signals, but no secondary, far-right signal head:


The through signals are fine, but a secondary, mast-mounted signal would have been a good fit here. Not pictured: this approach has two lanes (one straight, one right):


This approach (8 Street EB) is particularly maddening. The left turn originally had a secondary, post-mounted signal on the far left (mounted on the same post where the off-ramp's secondary signal head is located). For some reason, they did away with the secondary signal when they removed the pork-chop island. Most annoyingly, the replaced signal was only added in 2007. What standard changed between '07 and '16 that dictated fewer signals be used?


One intersection over is a signal maintained by the city of Pacific. This signal is unusal in that a five-section signal is mounted over the left turn lane (instead of to the right of it), but it results in good (nigh, great!) spacing. Also odd (though not necessarily related to the signal): the cross-street (Thornton) has a "left turn yield on green" sign, instead of typical "left turn must yield" sign typically used at junctions without left turn arrows (at least here in Washington):


Finally, the last signal, several miles away. Gigantic mast arm, signals right on top of each other :sigh:

In regards to the botom picture. Are those even aligned center to the corresponding lane?

[jakeroot]

In regards to the botom picture. Are those even aligned center to the corresponding lane?

Tip: You can cut out all the irrelevant bits of my post, just leaving the last photo. It helps reduce load times.

The two signals, which appear to be 12-feet wide, are placed inwards from the left and right edge of the straight/right lane by about two feet, so:

EDGE OF LANE : 2 FOOT BUFFER : LEFT SIGNAL : 8 FOOT BUFFER : RIGHT SIGNAL : 2 FOOT BUFFER : EDGE OF LANE

A better setup would have been to just use one overhead signal, between the left turn and straight/right lanes, and one on the left mast. Or if that's not allowed, one overhead and one on a pole to the right. WSDOT kind of handicapped themselves by only using two masts for the entire junction. Makes secondary signals harder to place, since masts have conduit inside of them that would allow easier placement of secondary signals.

[cl94]

I agree, those installations are completely ridiculous. I've never seen anything like that. When NYSDOT or one of the nearby agencies has a multi-lane approach like that, same-movement signals are at least one lane width apart. What might be better here is a spacing requirement tied to number of lanes/roadway width. 8 feet is fine for a single-lane approach, but for more, it's ridiculous. So you can get where I'm coming from,
this is a standard NYSDOT installation for multiple lanes and this is one for a narrow street. 8 feet is fine for the latter, but definitely not the former. Given the on-street parking, you can't really have supplemental signals here because they'd be blocked (Troy does indeed use supplementals in several locations).

Most of the agencies in this part of the country use 12' spacing unless lane width or some other weird condition dictates otherwise.

[SignBridge]

cl94, if that is a NYSDOT installation, it's the first time I've ever seen them use a box-span configuration. In the downstate region and on Long Island they only use diagonal-span. But you're right about NYS using generally good spacing on their signals, unlike some other states.

[cl94]

cl94, if that is a NYSDOT installation, it's the first time I've ever seen them use a box-span configuration. In the downstate region and on Long Island they only use diagonal-span. But you're right about NYS using generally good spacing on their signals, unlike some other states.

They've been switching to that Upstate in recent years, probably so signals aren't hanging in the middle of the intersection. Quite a few cases of signals falling in the middle of intersections on diagonal spans in recent years. Installs within the past year or two are generally either box span or mast arm.

But yeah, except for not having one head/lane until recently if there are more than 2 lanes/direction (quite a few intersections around with 2 heads for 4 straight lanes), NYSDOT has had nice installations for a long time, as do several of the larger local municipalities. Bad spacing is practically unheard of.

[SignBridge]

In recent years, NYSDOT has been using more mast-arms on Long Island than they used to, but still in a diagonal-span configuration. I only know of one incident here in Nassau County about 10 years ago, (a County installed signal) where a whole span-wire of 4 or 5 heads dropped into the street during a severe storm. Luckily with no casualties.

[jakeroot]

Here are some newer, much better installations from other areas of the Washington (installed/maintained by WSDOT). How exactly we've gone from these, to what ended up being installed in my photos above, really confuses me...WSDOT: seek help.

Curiously, the second and third photos are not MUTCD-compliant. The images are of off-ramps. Both feature double lefts, yet both only have one green orb (left signal is green arrow, right signal is green orb/green arrow). I know these used to be MUTCD-compliant, but recent changes require two through heads, even when the major movement is a left turn.

[SignBridge]

Yes, those look like very good installations, and they all look very new which might be a factor. New being more up-to-date with current practices. Maybe like with Calif. and New York DOT's, does it depend on the engineers in the particular regional office of WSDOT? And each office kind of does its own thing? And some do better than others?

[jakeroot]

Yes, those look like very good installations, and they all look very new which might be a factor. New being more up-to-date with current practices. Maybe like with Calif. and New York DOT's, does it depend on the engineers in the particular regional office of WSDOT? And each office kind of does its own thing? And some do better than others?

WSDOT is split into six regions: (clockwise from Whatcom County) Northwest, North Central, Eastern, South Central, Southwest, and Olympic.

The first and second photos are from the Southwest Region (Dollar Corner and Ridgefield, respectively). The third and fourth are from the Eastern region (Spokane Valley and Fairwood, respectively). The set of photos I posted above are from the Northwest Region. Which is annoying, because the Northwest Region is usually pretty good at signalization.

[jakeroot]

Washington continuing its fine tradition of placing signals right on top of each other. This isn't a state install, but seriously, what the fuck....(brand new signal, too)

https://goo.gl/RmN5db -- the right mast has no signal, so I'm not sure why they couldn't move one of the through heads over there.





Another atrocious setup, this time in Longview. This might be a state install, but I'm not sure (it's along Hwy 4).

https://goo.gl/uLVgMk -- This signal was installed in the age of good signal placement, so I'm not sure how this setup slipped through the cracks.

[roadfro]

Washington continuing its fine tradition of placing signals right on top of each other. This isn't a state install, but seriously, what the fuck....(brand new signal, too)

https://goo.gl/RmN5db -- the right mast has no signal, so I'm not sure why they couldn't move one of the through heads over there.

I can somewhat understand this one though, given the positioning of the lanes and other poles in comparison to the signal heads. The left through signal appears to align with the center of the through lane...

It's interesting to note that this mast arm already has other tenons on it already, so it wouldn't be hard to move the overhead through signals over to get decent separation (and then maybe turn the heads a bit to help with visibility).

[cl94]

Washington continuing its fine tradition of placing signals right on top of each other. This isn't a state install, but seriously, what the fuck....(brand new signal, too)

https://goo.gl/RmN5db -- the right mast has no signal, so I'm not sure why they couldn't move one of the through heads over there.

I can somewhat understand this one though, given the positioning of the lanes and other poles in comparison to the signal heads. The left through signal appears to align with the center of the through lane...

It's interesting to note that this mast arm already has other tenons on it already, so it wouldn't be hard to move the overhead through signals over to get decent separation (and then maybe turn the heads a bit to help with visibility).

The problem here is with the mast arm itself - it's not long enough. The turn signal should be about 8 feet to the left. The right through signal is over the right edge line - any further right and you'd have difficulty seeing it at a distance because of the other mast arms at the intersection (see GSV from 200 feet back.

[TheArkansasRoadgeek]

Jakeroot, in your photos I noticed that the street signs seem to either: be level or they are not. But, if so what would they be leveled to? The straitest portion of a cured mast? It must be like hanging a picture frame where one DOT worker is in a bucket truck and one is on the groud saying, "Up a little more. No, no, no, down and to the right just a hair!"

[roadfro]

Jakeroot, in your photos I noticed that the street signs seem to either: be level or they are not. But, if so what would they be leveled to? The straitest portion of a cured mast? It must be like hanging a picture frame where one DOT worker is in a bucket truck and one is on the groud saying, "Up a little more. No, no, no, down and to the right just a hair!"

I would think, ideally, the sign should be parallel to the flat ground below. Attaching a magnetic level to the sign during mounting should make accomplishing that easy.

[jakeroot]

Jakeroot, in your photos I noticed that the street signs seem to either: be level or they are not. But, if so what would they be leveled to? The straitest portion of a cured mast? It must be like hanging a picture frame where one DOT worker is in a bucket truck and one is on the groud saying, "Up a little more. No, no, no, down and to the right just a hair!"

I would think, ideally, the sign should be parallel to the flat ground below. Attaching a magnetic level to the sign during mounting should make accomplishing that easy.

Indeed. Street blades (well, any sign) should always be parallel with the ground. I've only seen one street blade that was mounted parallel to the mast arm, but it only lasted three days before being aligned to the street (as it should have). Perhaps there are jurisdictions that mount them parallel to the mast arm, but I've never heard of, or seen such a thing.

Arkansas Roadgeek, which image above was it that had the crooked street blade? All the images that I posted have street blades parallel to the ground.

[thenetwork]

[qoute]
UT-US191-ArchesS by Paul Drives, on Flickr
[/quote]

If I am not mistaken,  these are very new lights.  I drove thru there right after Easter and I didn't recall seeing them then.  We visted Arches today and unfortunately we came and went from the south. 

One interesting factoid:  Despite a long frontage road leading up to the "toll booths" for the park, if traffic backs up to and onto US-191, you are required to pass the entrance, turn around and try to enter again.  Problem is, if coming from the south, you must go north 5 MILES before you can (legally) turn around.  Coming in from the north, you only have to go about a mile or less.

We got there about 11am today, and the frontage road was lined up 3/4th of the way -- stI'll took us between 30-45 minutes to get up to the 2 entry toll booths.

My Mom-in-law was with us so instead of paying the $25 entry fee, she bought the $10 lifetime senior pass.  I mention this that if you are, or have access to a senior, the $10 lifetime pass is slated to jump to $80 by year end.  Since my mom-in-law doesn't drive, she will be our passage into the area parks!!!

[jakeroot]

If I am not mistaken,  these are very new lights.  I drove thru there right after Easter and I didn't recall seeing them then.  We visted Arches today and unfortunately we came and went from the south.

Are you talking about this post, from two pages back? I think it's safe to say you are, but please insert the relevant quote next time. thanks!

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

[thenetwork]

If I am not mistaken,  these are very new lights.  I drove thru there right after Easter and I didn't recall seeing them then.  We visted Arches today and unfortunately we came and went from the south.

Are you talking about this post, from two pages back? I think it's safe to say you are, but please insert the relevant quote next time. thanks!

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

Sorry, I hit the REPLY tab instead of the QUOTE tab.