Span Wire Vs Mast Arm

[mrsman]

I think it's a good thing to have LPI on left turns.  Haven't yet seen it in areas that I frequent.  I also prefer lagging left turns since in most permissive left turns, there are always people who make the left at the end of the cycle.  Putting the left turn at the end of the cycle therefore seems natural to me.  Of course all concerns with yellow trap have to be met and the fya does that.

LPI s do not need to be made standard.  they are really helpful in areas with significant pedestrian crossing should be utilized more in such areas.  There is no need for them to be incorporated in every intersection though.

Nexus 5X

[tradephoric]

I also prefer lagging left turns since in most permissive left turns, there are always people who make the left at the end of the cycle.  Putting the left turn at the end of the cycle therefore seems natural to me.  Of course all concerns with yellow trap have to be met and the fya does that.

Leading lefts should maximize the capacity of an isolated intersection.  Suppose a NB LT gaps out early.  That extra time can be given to the SB THRU (even as the SB LT is still running).  With lagging lefts you can't reintroduce the THRU phase since it has already ran (so when that NB LT wants to gap out early it can't... and that's just wasted green time). 

[mrsman]

I also prefer lagging left turns since in most permissive left turns, there are always people who make the left at the end of the cycle.  Putting the left turn at the end of the cycle therefore seems natural to me.  Of course all concerns with yellow trap have to be met and the fya does that.

Leading lefts should maximize the capacity of an isolated intersection.  Suppose a NB LT gaps out early.  That extra time can be given to the SB THRU (even as the SB LT is still running).  With lagging lefts you can't reintroduce the THRU phase since it has already ran (so when that NB LT wants to gap out early it can't... and that's just wasted green time).

I see you revived the PPLT thread, so I'll reply to your point over there.

[ET21]

Idk why, but I prefer mast arms. Makes the intersection look cleaner

[roadman65]

I like Florida and Texas as both states use them both equally. 

[SignBridge]

ET21, I believe most in the traffic engineering field regard mast-arms as the cleaner looking, aesthetically pleasing design compared to span-wire installations. However I have to say that on Long Island, New York State DOT Region-10 and Nassau County DPW build the neatest, cleanest diagonal span installations I've ever seen. I was surprised at how sloppy some span-wire signals look in other states in the Northeast.

[RobbieL2415]

We seem to do both here. Older installations are typically wire-hung, though.

[democratic nole]

Anyone that answered span wire as preferable to mastarms should quit using drugs.

In all seriousness, this has been a pet peeve of mine since I was a child. Florida, where i mostly grew up, historically used almost exclusively span wire signals. I also grew up in Texas where there was a mix. Upon my first trip to Chicago as a kid, I marveled at how every signal in Chicago was on a clean and neat looking mastarm, which greatly improved both visibility and aesthetics. 

My general experience is that states that do not make regular use of mastarms do a poor job of installing them. Michigan and Georgia are great examples of this. Florida can be hit or miss on their installation. Tampa is especially annoying in that it is trying to be cheap by combining signals for multiple directions on a single or two mastarms, which not only look terrible but hurt visibility at the stop bar for some approaches. For example: https://www.google.com/maps/@27.963118,-82.4676612,3a,75y,6.16h,81.16t/data=!3m6!1e1!3m4!1s1UGWKijIMOi5lzYOBszOKw!2e0!7i16384!8i8192?hl=en&authuser=0
https://www.google.com/maps/@27.9519833,-82.4723914,3a,75y,267.29h,95.61t/data=!3m6!1e1!3m4!1sHguOJw6LsPe6iFzltWd1_Q!2e0!7i16384!8i8192?hl=en&authuser=0

With Florida's hurricanes, mastarm installation should be universal here but it is not. When South Florida had its 2004 hurricanes, Broward County lost something like 60% of their traffic signals due to failure in high winds. Rather than just make mastarm installation mandatory, FDOT wasted a bunch of money on a study to find a way to keep installing crappy looking mastarms with higher wind loads, that are still inferior to mastarms. Even when there are not hurricane level winds, we still get severe thunderstorms here that blow the span wire signals around strongly and make visibility difficult. FDOT D7 here in Tampa has started installing this single wire spans (as someone else pointed out) and they are absolutely atrocious in high winds. https://www.google.com/maps/@27.9667829,-82.5054504,3a,75y,15.07h,81.91t/data=!3m6!1e1!3m4!1svizaYgU6YNJTz8xZzEZ1OA!2e0!7i16384!8i8192?hl=en&authuser=0

Conversely, states that are essentially universal in installing mastarms, such as California, Nevada, and Arizona, do an excellent job of making the mastarms look sharp. I've always thought California was the gold standard for signal installation, due to universal mastarm installation and almost universal use of supplemental side mounts, both on the far and near side of the intersection. As an example: https://www.google.com/maps/@33.8595203,-117.8178331,3a,75y,262.52h,78.67t/data=!3m7!1e1!3m5!1sAF1QipM3uLZVieS3mEdgIRpg3Kt3Y3qXf5O1-3TlcC8f!2e10!3e11!7i11000!8i5500?hl=en&authuser=0

[US 89]

Even mast arms aren't fully immune to wind, as this 2013 article from the Deseret News shows...



To be fair, these probably would have survived if the big power lines next to the highway hadn't taken them out...

[jakeroot]

In all seriousness, this has been a pet peeve of mine since I was a child. Florida, where i mostly grew up, historically used almost exclusively span wire signals. I also grew up in Texas where there was a mix. Upon my first trip to Chicago as a kid, I marveled at how every signal in Chicago was on a clean and neat looking mastarm, which greatly improved both visibility and aesthetics.

Without quoting the whole post: I think you and I will get along just fine .

We can certainly agree on California, Illinois, Nevada, Arizona, et al when it comes to signals. Those states all have fairly consistent designs with heavy mast arm use. Aesthetically, I think a typical mast arm install is superior to anything involving excessive wires (including those box span installs with wires along the bottom and top of the signals, even if they "sturdier").

[democratic nole]

In all seriousness, this has been a pet peeve of mine since I was a child. Florida, where i mostly grew up, historically used almost exclusively span wire signals. I also grew up in Texas where there was a mix. Upon my first trip to Chicago as a kid, I marveled at how every signal in Chicago was on a clean and neat looking mastarm, which greatly improved both visibility and aesthetics.

Without quoting the whole post: I think you and I will get along just fine .

We can certainly agree on California, Illinois, Nevada, Arizona, et al when it comes to signals. Those states all have fairly consistent designs with heavy mast arm use. Aesthetically, I think a typical mast arm install is superior to anything involving excessive wires (including those box span installs with wires along the bottom and top of the signals, even if they "sturdier").

You clearly have superior intelligence lol.

[STLmapboy]

Apparently MO has some new span wires around (this one dates from 2015). It's a decent box span with wires under the signals and FYAs, but still, it's a span wire.

[JoePCool14]

Apparently MO has some new span wires around (this one dates from 2015). It's a decent box span with wires under the signals and FYAs, but still, it's a span wire.

Clean install. I see nothing wrong with this.

[Ned Weasel]

Apparently MO has some new span wires around (this one dates from 2015). It's a decent box span with wires under the signals and FYAs, but still, it's a span wire.

Clean install. I see nothing wrong with this.

I wish the road name sign was bigger.

[SignBridge]

It still looks sloppy compared to a good quality mast-arm installation like you'd find in California, Nevada or Chicagoland.

[tdindy88]

Apparently MO has some new span wires around (this one dates from 2015). It's a decent box span with wires under the signals and FYAs, but still, it's a span wire.

That's the standard span wire design for Indiana. Nearly all stoplights that use span wires are designed this way and IMO look pretty decent as a result. Certainly compared to what I see in Ohio and Kentucky with their span wires. There's also plenty of mast arm designs throughout the state in the more urbanized parts of the cities. Still, I find Illinois's mast arms to be very nice statewide.

[MCRoads]

I know I'm a bit late, but this bridge in CO Springs has the lights hanging from the deck, not the beams! Good way to mount on a bridge and not be so high! I could swear there was a more pronounced exam, but I can't find it right now.

[jakeroot]

Just as an example, the MO install in the above link compared to a mast-arm install in Puyallup, WA. Both single-lane approaches with right turn bypasses and FYA left turns:





Another mast arm install in Federal Way, WA:

[paulthemapguy]

Many elements of a traffic signal are useful for announcing the signal's presence.  These elements include 12-inch sections (which are now standard), backplates, and in my opinion, mast arms.  I prefer mast arms because they make a signal more readily visible from a greater distance.  An Indiana signal with span wires and naked signal heads without backplates will be anticipated by me much sooner later than an Illinois signal with mast arms and backplates, giving me much less time to react.  Plus, with mast arms, you don't have problems with signal heads waving around or rotating to face upward or downward. (edited, see below)

[JoePCool14]

Many elements of a traffic signal are useful for announcing the signal's presence.  These elements include 12-inch sections (which are now standard), backplates, and in my opinion, mast arms.  I prefer mast arms because they make a signal more readily visible from a greater distance.  An Indiana signal with span wires and naked signal heads without backplates will be anticipated by me much sooner later than an Illinois signal with mast arms and backplates, giving me much less time to react.  Plus, with mast arms, you don't have problems with signal heads waving around or rotating to face upward or downward.

I think you mixed up your words a bit. FIFY.

As for my opinions on this topic, I believe it's just the fact that I'm from Illinois (i.e., the land of mast arms), and when I think of span wire signals, I think of other states. When I think of other states, I think of vacations. So there's definitely bias here that I enjoy a good span wire signal, I won't even try to deny that. I think both have their use cases. And I think both can look good and both can look bad.

[SignBridge]

Many elements of a traffic signal are useful for announcing the signal's presence.  These elements include 12-inch sections (which are now standard), backplates, and in my opinion, mast arms.  I prefer mast arms because they make a signal more readily visible from a greater distance.  An Indiana signal with span wires and naked signal heads without backplates will be anticipated by me much sooner later than an Illinois signal with mast arms and backplates, giving me much less time to react.  Plus, with mast arms, you don't have problems with signal heads waving around or rotating to face upward or downward.

I think you mixed up your words a bit. FIFY.

As for my opinions on this topic, I believe it's just the fact that I'm from Illinois (i.e., the land of mast arms), and when I think of span wire signals, I think of other states. When I think of other states, I think of vacations. So there's definitely bias here that I enjoy a good span wire signal, I won't even try to deny that. I think both have their use cases. And I think both can look good and both can look bad.

JPC14, I generally dislike span-wire, but the best quality installations I've seen are those done by New York State DOT and Nassau County DPW on Long Island.

And Paul, 12-inch heads are not standard everywhere in the country even nowadays. Regrettably the agencies I mentioned still use a mix of both sizes. Usually 12-inch for the main road and either 12 or 8 inch for a smaller intersecting road. I assume it depends on the judgment of the engineer who spec's it. But I agree that 12-inch should be standard almost everywhere in new and rebuilt installations.

[jakeroot]

^^^^
I was still seeing 12-8-8 signals installed in WA up until about 2008, but none since that I can recall.

I think 12 inch signal heads are the 'default' in the US, with 8 inch heads being used only as necessary. However, this is not the case in Canada. British Columbia still calls for 8-inch heads under certain circumstances.

[Scott5114]

What circumstances would call for smaller, and thus less visible, signal heads? I would think 12" signals would be preferable in every situation.

I like 12-8-8 signals on an aesthetic level, and the novelty since Oklahoma never used them much, if at all. But I'm sure the reduced yellow and green lenses are less optimal on a safety level.

[Amtrakprod]

I've only seen new 12-12-8 emergency signals recently.


iPhone

[MCRoads]

What circumstances would call for smaller, and thus less visible, signal heads? I would think 12" signals would be preferable in every situation.

I like 12-8-8 signals on an aesthetic level, and the novelty since Oklahoma never used them much, if at all. But I'm sure the reduced yellow and green lenses are less optimal on a safety level.

I like 12-8-8 as well, it looks cool. The traffic signal I got is 21-8-8, and green (my favorite color, also pretty uncommon now) to boot!