Span Wire Vs Mast Arm

[jakeroot]

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

I checked the BC MOT Signal Design Manual (see here), and they've actually changed the manual to call for 300mm (12") heads for all new primary, secondary, and auxiliary signals. This change seems to have occurred in the last year or two.

This is actually quite a major change, as 200mm signals are very common for secondary (mounted on poles) and auxiliary (near-side pole) signals, with only some cities (Coquitlam being one example) installing 300mm signals for all installations consistently. Along MOT-maintained roads, 200mm signals were still being installed as of 2019 (see here).

I think the primary argument was that 300mm signals did not provide enough additional visibility for them to absolutely require it. 300mm signals have always been an option, and they've been installed under all circumstances (primary, secondary, auxiliary) for decades. The difference being that it's never been a requirement. It's similar to the "category b" section of MUTCD 2E: destinations can be 20" UC, but this is not strictly necessary, as 16" UC provides sufficient readability under most circumstances. Similarly, 200mm signals provide sufficient visibility under most circumstances. I suspect the change to 300mm signals will make signals cheaper and easier to install, especially in terms of mounting hardware, with improved visibility being only a small benefit (and only under certain circumstances at that).

This former practice echoes that of Australia, where 200mm signal heads are standard, and 300mm signal heads are only used as warranted (example here north of Brisbane).

In my opinion, if you're looking to have the greatest impact on signal visibility, the best practice is not to have only jumbo-sized overhead signals (when will 12" be considered small?), but a series of primary, secondary, and auxiliary signals in different positions. You can combine the two, but I'd recommend 'extra signals' before having only larger primary signals, as is the way in many US states (OR, WA, IN, etc).

[epzik8]

Lately Maryland has been replacing a lot of span wires with mast arms. They're doing US 40 at MD 132/APG Boulevard in Aberdeen right now.

[STLmapboy]

Discovered some more newish span wires in MO.

[jakeroot]

Lately Maryland has been replacing a lot of span wires with mast arms. They're doing US 40 at MD 132/APG Boulevard in Aberdeen right now.

I'm trying to remember where in Maryland I've seen span wire. Seems like in the DC area, they're mostly mast arm.

MD signals are easy to remember, for me, as there's almost always a near-side signal, and they use those 12-12-8-8-8 doghouses rather frequently.

[STLmapboy]

Does anyone know of signal installations that are half wire, half mast arm? I drove past this one the other day. I also know that Houston has several. Any others?

[HTM Duke]

^Intersection of SR-648/Edsall Rd and Independence Cir / Winter View Dr in Alexandria, VA:

https://goo.gl/maps/AM4yuLw3bs2jZ5Mq6

This installation was originally all mast arms, but something happened between 2017-18 that forced VDOT to remove the mast arm and signals at the southeast corner of the intersection and replace it with a diagonal spanwire.  (A bit peculiar as well is the sight of a ped signal mounted to a wooden 4x4.)  I'm left to speculate that VDOT is waiting for routine signal replacement before they possibly erect a new mast arm.

[EpicRoadways]

Does anyone know of signal installations that are half wire, half mast arm? I drove past this one the other day. I also know that Houston has several. Any others?

For about five years there was an intersection near me in which 3 of the 4 directions were span wire. I think the reasoning behind it was that different approaches to the intersection were upgraded at different times. You can see the evolution of the intersection pretty well in GSV, but basically the approach with the one mast arm facing it was completed in 2015 as part of the initial widening project on that approach (which is also when the signal bases/light poles for the other approaches were installed with span wires). However, funding constraints prevented other planned improvements at the intersection from being constructed (notably a dual-left turn lane and some realignment and lengthening of the right turn lanes). Those improvements were completed in 2019 and now the intersection is all mast arms.

Normally in a situation like this in Minnesota if a signal system is upgraded at an intersection where there are improvements planned in the near future either every direction gets mast arms with additional space for more signals (example) or the entire intersection gets a "true" temporary span wire signal (wood vertical bases, etc.) until the work is completed and a new permanent signal is installed. This example is the best (or worst) or both worlds, I guess. I haven't seen anything else like it anywhere in the state.

[renegade]

Does anyone know of signal installations that are half wire, half mast arm? I drove past this one the other day. I also know that Houston has several. Any others?

Yeah, this one in VanBuren Twp, MI:

https://www.google.com/maps/@42.2219511,-83.4852147,3a,75y,161.52h,96.97t/data=!3m6!1e1!3m4!1sCM-3M0EpoTxxcmdGeGINOg!2e0!7i16384!8i8192

Belleville Rd. at I-94

[CardInLex]

Does anyone know of signal installations that are half wire, half mast arm? I drove past this one the other day. I also know that Houston has several. Any others?

This one in Danville, KY. Since Google Streetview last photographed, the eastern mast arm on Main Street has been replaced with a span wire (the existing mast arm still remains in place with signals moving to the span wire–done to accommodate new left turn signalization). Both of the span wires are temporary, as the city is working with KYTC to replace all signals with a new streetscape project in the next few years.

https://goo.gl/maps/9jHsLH2uKC7N7s7RA

[epzik8]

Lately Maryland has been replacing a lot of span wires with mast arms. They're doing US 40 at MD 132/APG Boulevard in Aberdeen right now.

Here is some work I caught on this from last month. This is also my 1,000th post:

[epzik8]

Lately Maryland has been replacing a lot of span wires with mast arms. They're doing US 40 at MD 132/APG Boulevard in Aberdeen right now.

I'm trying to remember where in Maryland I've seen span wire. Seems like in the DC area, they're mostly mast arm.

MD signals are easy to remember, for me, as there's almost always a near-side signal, and they use those 12-12-8-8-8 doghouses rather frequently.

I know that there are a good amount of span wires along US 301 between the Nice Bridge and Bowie, although there are a lot of mast arms in the Waldorf-St. Charles area. I also seem to recall some span wires along US 50 in the Easton area. Just about all of the span wires on MD 24 between I-95 and US 1 in Harford County have been replaced with mast arms.

[jakeroot]

Lately Maryland has been replacing a lot of span wires with mast arms. They're doing US 40 at MD 132/APG Boulevard in Aberdeen right now.

I'm trying to remember where in Maryland I've seen span wire. Seems like in the DC area, they're mostly mast arm.

MD signals are easy to remember, for me, as there's almost always a near-side signal, and they use those 12-12-8-8-8 doghouses rather frequently.

I know that there are a good amount of span wires along US 301 between the Nice Bridge and Bowie, although there are a lot of mast arms in the Waldorf-St. Charles area. I also seem to recall some span wires along US 50 in the Easton area. Just about all of the span wires on MD 24 between I-95 and US 1 in Harford County have been replaced with mast arms.

I was actually in Waldorf back in January, but I was only on US-301 for a short distance (and not in an area that had any wire span) after coming east on MD-228 via southbound MD-210 heading out of DC. Now that you mention it, I recall seeing some wire span signals along MD-210.

[democratic nole]

Does anyone know of signal installations that are half wire, half mast arm? I drove past this one the other day. I also know that Houston has several. Any others?

Fort Worth has a few of those where the mainline road has mastarms and the auxillary road has the span wire signal.

I am not sure there are uglier traffic signals in the country than Houston area horizontal span wire signals. 

[democratic nole]

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:

As much money is in the Seattle area, I do not understand the City of Seattle's widespread use of terrible span wire signals. Seems like the Seattle suburbs (Bellevue comes to mind) have rather good mastarm installation, but it is frankly embarrassing that one can drive around downtown Seattle and see span wire signals everywhere.

[davewiecking]

Mast arms 100%. I hate traffic signals dancing in the wind. Especially non-standard non-right angle intersections where you really need to know which light sort of aimed in your direction is the one to be followed.

[Amtrakprod]

With apologies for bringing up politics on this board, it's not exactly surprising about Seattle considering what we've seen of its city government over the past year. Their priorities are obviously very misplaced.

I don't think that's true, especially with their bike infrastructure, but okay.


iPhone

[NoGoodNamesAvailable]

With apologies for bringing up politics on this board, it's not exactly surprising about Seattle considering what we've seen of its city government over the past year. Their priorities are obviously very misplaced.

You can complain about seattle all you want, but that city, and the PNW in general, has better and more innovative signalization practices than 90% of the country. That's the only reason you notice the span wire. In places like NY state ugly span wire and poor signal placement are just expected as the norm.

[SignBridge]

Points taken guys. Apparently the issues are more multi-sided than I realized. It's all good.

[JoePCool14]

With apologies for bringing up politics on this board, it's not exactly surprising about Seattle considering what we've seen of its city government over the past year. Their priorities are obviously very misplaced.

Yup, posting this was like throwing down a lit bomb. But I digress...

I've perused Seattle on StreetView and the span wires generally don't look at that great. I know earlier in on this topic I said span wires could be appropriate. However, in any sort of urban core environment, you really need mast arms.

[jeffandnicole]

Does anyone know of signal installations that are half wire, half mast arm?

Very unusual for NJ is the traffic light setup at this new intersection on US 322 at the new Inspira Hospital near NJ 55.

https://maps.app.goo.gl/saPN3SezkNXgkoGw9

While shown here in the construction phase, this is how they completed the project. And odder still...the main road: US 322, has the span wire; the side road has the mast arms.

It does appear there are in-ground bases for posts and mast arms for 322. My guess is that there was some sort of issue with those bases or the traffic light structues, and they went with a Plan B for a while.

[Caps81943]

^Intersection of SR-648/Edsall Rd and Independence Cir / Winter View Dr in Alexandria, VA:

https://goo.gl/maps/AM4yuLw3bs2jZ5Mq6

This installation was originally all mast arms, but something happened between 2017-18 that forced VDOT to remove the mast arm and signals at the southeast corner of the intersection and replace it with a diagonal spanwire.  (A bit peculiar as well is the sight of a ped signal mounted to a wooden 4x4.)  I'm left to speculate that VDOT is waiting for routine signal replacement before they possibly erect a new mast arm.

Random question, would anyone know how old those lights (on the mast) are? I feel like that design of light (with that back) is the oldest traffic light style that's still common in VA.

[democratic nole]

However, in any sort of urban core environment, you really need mast arms.

That was my main point about the Seattle signals. It is maybe the only large city I am aware of where span wire seems to be the prevalent installation mode for signals in a downtown area. I don't know how they could ever allow https://goo.gl/maps/bRdnHPo8v6diWsZd9

[jakeroot]

However, in any sort of urban core environment, you really need mast arms.

That was my main point about the Seattle signals. It is maybe the only large city I am aware of where span wire seems to be the prevalent installation mode for signals in a downtown area. I don't know how they could ever allow https://goo.gl/maps/bRdnHPo8v6diWsZd9

There are definitely more examples than just Seattle. Vancouver, BC has an extensive amount of span wire in their downtown. Both Seattle and Vancouver have plenty of mast arms as well. The use of span wire is by no means close to a universal practice in either city. Where I live, in Tacoma, another large PNW city, span wire is also very prevalent throughout the downtown core.

There are many reasons why span wire is preferred in urban areas:

(1) easier to modify later if lane layouts change
(2) easier to work into trolley wire setups (esp. important in Vancouver and Seattle)
(3) mast arms are bulky and can be inappropriate in tighter urban areas. Small mast arms, like in Spokane, WA, are a good compromise.
(4) mast arms do nothing to improve signal visibility, which is better achieved through backplates (which Seattle makes extensive use of).

In downtown Seattle and downtown Vancouver, span wire likely became popular early on because overhead signals showed up pretty quickly over a short period of time, mostly in the 70s and 80s, and the cost to implement overhead signals with mast arms would have far exceeded most budgets given the sheer number of signalized intersections. Few modifications have taken place since then, so span wire remains common. This is especially true in Vancouver, where most signals are post-mounted and where the span wire signals were mostly added only to aid in signal visibility.

It should be noted that both cities have plenty of mast arms. Both old and new examples of both can be found throughout each city. In Downtown Seattle, a large number of intersections use only post mounted signals. Many signals that are not post mounted, such as those along 2nd Ave and 5th Ave, are mast arms. Never mind the huge number of mast arms outside of the downtown area.

Basically: don't rag on Seattle because (A) they're not unique in using span wire, (B) they have good reasons to use it, and (C) many intersections don't use span wire anyway.

Couple other things, too: new span wire is hard to come by in WA no matter where you are. Many cities have never used it. Additionally, in that above photo quote (original quote from me), the only intersection in that picture with span wire is from Missouri, and the other two pictures are not from Seattle. What in the hell made you bring up Seattle?

As to the comments above about politics: get the f*** out of here with that shit. It has nothing to do with traffic lights.

[Amtrakprod]

However, in any sort of urban core environment, you really need mast arms.

That was my main point about the Seattle signals. It is maybe the only large city I am aware of where span wire seems to be the prevalent installation mode for signals in a downtown area. I don't know how they could ever allow https://goo.gl/maps/bRdnHPo8v6diWsZd9

There are definitely more examples than just Seattle. Vancouver, BC has an extensive amount of span wire in their downtown. Both Seattle and Vancouver have plenty of mast arms as well. The use of span wire is by no means close to a universal practice in either city. Where I live, in Tacoma, another large PNW city, span wire is also very prevalent throughout the downtown core.

There are many reasons why span wire is preferred in urban areas:

(1) easier to modify later if lane layouts change
(2) easier to work into trolley wire setups (esp. important in Vancouver and Seattle)
(3) mast arms are bulky and can be inappropriate in tighter urban areas. Small mast arms, like in Spokane, WA, are a good compromise.
(4) mast arms do nothing to improve signal visibility, which is better achieved through backplates (which Seattle makes extensive use of).

In downtown Seattle and downtown Vancouver, span wire likely became popular early on because overhead signals showed up pretty quickly over a short period of time, mostly in the 70s and 80s, and the cost to implement overhead signals with mast arms would have far exceeded most budgets given the sheer number of signalized intersections. Few modifications have taken place since then, so span wire remains common. This is especially true in Vancouver, where most signals are post-mounted and where the span wire signals were mostly added only to aid in signal visibility.

It should be noted that both cities have plenty of mast arms. Both old and new examples of both can be found throughout each city. In Downtown Seattle, a large number of intersections use only post mounted signals. Many signals that are not post mounted, such as those along 2nd Ave and 5th Ave, are mast arms. Never mind the huge number of mast arms outside of the downtown area.

Basically: don't rag on Seattle because (A) they're not unique in using span wire, (B) they have good reasons to use it, and (C) many intersections don't use span wire anyway.

Couple other things, too: new span wire is hard to come by in WA no matter where you are. Many cities have never used it. Additionally, in that above photo quote (original quote from me), the only intersection in that picture with span wire is from Missouri, and the other two pictures are not from Seattle. What in the hell made you bring up Seattle?

As to the comments above about politics: get the f*** out of here with that shit. It has nothing to do with traffic lights.

Never attack Washington when Jake is around


iPhone

[SignBridge]

Since there have been several negative reactions to my earlier post that referenced Seattle city politics as it relates to traffic signals, I have removed the post. Point taken; I probably shouldn't have posted that on this board. My apologies to anyone who was offended.