Traffic signals hanging by cables?

[ZLoth]

OK, so I've lived in California for 85% of my life, so pardon if I sound strange, but I was reading thread    
Traffic Signals Now Controlled By Stop Signs , and I noticed how many signals are just hanging by cables. To my eyes, that's unusual, as traffic signals around here are, almost without exception, handing within steel "standards" (I'm sure someone will correct me). I can look at the Sacramento climate records, and the high temperatures would probably bake the cables around here. Plus, the building code requires that buildings withstand a 70mph wind which has happened several times in Sacramento. Yet, I see signals hanging in states which are known to be hit by hurricanes in the past hanging by wires.

Can someone enlighten me on this?

[signalman]

They're known as span wires.  It's a less expensive installation for cash strapped states. It does, however, require more maintenance than a mast arm installation or similar mounting method.  They are quite common on the east coast outside of urban areas.

[on_wisconsin]

The State of Wisconsin bans span wire installations for all non-temporary purposes:
WMUTCD, Section 4D.11

G. Permanent traffic signals shall not be installed on overhead cables or any other means which would permit significant movement under windy conditions.
Option:
Temporary traffic signals may be installed on overhead cables if construction or maintenance operations would not make post or mast arm mounting possible. If installed on overhead cables, temporary traffic signals must be converted to post or mast arm mountings as soon as possible after the construction operation permits.

 
Span wire stop lights look very unkept and do not reflect any sense of care by the maintaining agency. IMHO

[Ned Weasel]

These are especially common in Indiana, Michigan, and Ohio.  I always assumed they were normal in the less tornado-prone states (which might partially explain why the ones in Kansas are often temporary*).  I actually like the way they look when they're done well.  I consider them "done well" when the signal heads are in a consistent style, when the spacing of features is even or shows purposeful relationships, and when the signs are aligned properly (not crooked).  I think span wire signal installations often give a "lightened up" appearance, while mast arm installations can look "weighty."  Of course, anything can be done poorly, whether it's hung from a span wire or a mast arm.  The difference lies in whether you can observe a clear design intent.

It's usually easy to tell the difference between a decent permanent installation and a temporary one.  Here two examples off the top of my head:

Permanent: one of several along M-102/8 Mile Road (although you could probably pick any major arterial road in Michigan for similar examples): https://maps.google.com/maps?ll=42.445691,-83.170795&spn=0.009089,0.021136&t=m&z=16&layer=c&cbll=42.445694,-83.170962&panoid=dNQSmM6c6MW9AMUSpMUpWQ&cbp=12,243.96,,0,-4.11

Temporary: US 54/400/Kellogg Avenue (future freeway): https://maps.google.com/maps?ll=37.679242,-97.232518&spn=0.00121,0.002642&t=m&z=19&layer=c&cbll=37.679253,-97.232676&panoid=zQIYMBkSag1xeOgPxkgG6Q&cbp=12,68.28,,0,4.29

*5/21/2016 edit: I corrected myself regarding this point.

[jeffandnicole]

I don't think there's really any correlation between where span wife states and natural hazards. Over time, various states came up with various standards. Simple as that.

[hbelkins]

Kentucky uses mostly span wire. Doesn't bother me, and is probably less expensive than other types of mounting.

[theline]

Here's a recent span wire installation in Indiana that I think is a real mess: https://www.google.com/maps/@41.698566,-86.137476,3a,75y,90t/data=!3m4!1e1!3m2!1sU6muZcnACud09s88yoQMjQ!2e0?hl=en

I'm not sure if there is a good solution to this, though I'd like to hear your ideas. If mast arms were used, they would have to be very long, because these roads are so wide. Note that signals are, of necessity, so far back from the beginning of the intersection, that INDOT installed an extra signal face at the near side.

I've driven through here many times, and it does work, but boy is it ugly!

[roadman65]

Span wires are cheaper than mast arms, but it depends on the states.  Here in Florida it is optional.  California, New Jersey, Arizona, and Kansas they uses arms exclusively except for temporary installations.

North Carolina, Georgia, South Carolina, Kentucky, and even some New England States use span wires as their norm with occasional mast arms in urban areas.

To me it is all who hangs the assemblies as some mast arms are very sloppy as much as some of the mast arms are.  However, if the span wires are hung diagonally across major intersections with large parameters they look more professional in that location.  Box within a box, as Georgia uses, looks too tangled, but I heard from a friend who used to repair traffic signal assemblies tell me that practice is great for high wind conditions as well as the X wire placing which Orlando uses on Kirkman Road at Universal Studios Theme Parks entrance.

[roadman65]

Here's a recent span wire installation in Indiana that I think is a real mess: https://www.google.com/maps/@41.698566,-86.137476,3a,75y,90t/data=!3m4!1e1!3m2!1sU6muZcnACud09s88yoQMjQ!2e0?hl=en

I'm not sure if there is a good solution to this, though I'd like to hear your ideas. If mast arms were used, they would have to be very long, because these roads are so wide. Note that signals are, of necessity, so far back from the beginning of the intersection, that INDOT installed an extra signal face at the near side.

I've driven through here many times, and it does work, but boy is it ugly!

This one if it were Caltrans, would use the short mast arms and side mount signals on each of the four corners.  Plus the left turn signals, if any, would be placed in the median on a 6 foot or higher mast pole.

New Jersey would place mast arms from every corner with two arms ascending one pole plus some mast arms extending from the median.

Ontario Canada, has one head per arm, but has one arm from the right side corner and one mast arm from the left (either the median or left side of the road) as standard practice to make the necessary two heads per way.

There are all kinds of way of doing it.

[Big John]

^^ A solution is to put diagonal cables starting at all 4 corner posts then have them connect an inner cable square above the intersection in which the signals are supported so they are closer to the stop line.

[route56]

(which is why the only ones you'll see in Kansas are temporary)

Not necessarily:

48645 by richiekennedy56, on Flickr

Granted, KDOT chose a span-wire installation at 6th Street and K-10 because KDOT is looking at making this interchange a DDI.

[Brian556]

Florida really does have a wide variety of signal installations.

Span Wire varieties include:
1. box
2. single diagonal wire
3. two diagonal wires
Examples:
SR 535& SR 536
https://maps.google.com/?ll=28.357145,-81.497061&spn=0.000002,0.000774&t=h&z=21&layer=c&cbll=28.357145,-81.497061&panoid=uBDjso2zsikzVM6jMYwm0A&cbp=12,334,,0,0

SR 436 & SR 426
https://maps.google.com/?ll=28.604094,-81.307319&spn=0.000002,0.001549&t=h&z=20&layer=c&cbll=28.604094,-81.307319&panoid=H1hoXSZBW6XpjrhSbtdqUg&cbp=12,358.56,,0,0

4. X
Example: US 301 & SR 44 in Wildwood:
https://maps.google.com/?ll=28.847136,-82.04577&spn=0.000019,0.012392&t=h&z=17&layer=c&cbll=28.847134,-82.045911&panoid=gYsgxhHE-CaG4xR7GgGsfQ&cbp=12,96.37,,0,0

5. X with box inside (Can't think of any examples)

[freebrickproductions]

Here are a few spanwire set-ups on a wiki I help maintain:
http://highwaydivides.com/wiki/index.php?title=Signal_Mounting_Styles#Span_Wires

[WichitaRoads]

(which is why the only ones you'll see in Kansas are temporary)

Not necessarily:

48645 by richiekennedy56, on Flickr

Granted, KDOT chose a span-wire installation at 6th Street and K-10 because KDOT is looking at making this interchange a DDI.

And, let's not forget a number of span lights in Wichita, especially along Southeast Blvd. They have been fased out slowly here, but it some areas that last saw updates in 1968 or 78, well, they still have spans.

ICTRds

[1995hoo]

I've always been surprised to see as much span wire as I have in Florida. I'd have expected to see more mast arms there because I'd assume they're more durable. On the other hand, span wire does have the advantage of allowing the authorities to remove the lights and the wire in advance of a major storm like a hurricane if desired. I don't know whether that's ever done in Florida, but I remember in September 1996 when Hurricane Fran ripped through North Carolina, Durham County authorities took down lots of span-wire traffic signals in advance of the storm and fastened the wire around the poles on each corner.

Here in Northern Virginia, span wire used to be the norm, but nowadays mast arms are typical for new installations.

[PurdueBill]

The Indiana example above is an outlier for Indiana in my experience though...usually their span wire assemblies look pretty good because of the "extra" wires (most places either use a cable below the signals or an extra bracing one above; INDOT uses both even with single-head flashing lights).  If they'd had a mast in the median of the intersecting road above, they could have had the signals closer to the stop lines on 331, but there would have been a slight angle to everything. 

Delaware has always had a ton of span wire assemblies but does use masts sometimes.  Massachusetts also has a fair number of span wire assemblies, especially at larger intersections.  Ohio loves span wire assemblies as well, including the type with the inner box.

[ZLoth]

Here's a recent span wire installation in Indiana that I think is a real mess: https://www.google.com/maps/@41.698566,-86.137476,3a,75y,90t/data=!3m4!1e1!3m2!1sU6muZcnACud09s88yoQMjQ!2e0?hl=en

I'm not sure if there is a good solution to this, though I'd like to hear your ideas. If mast arms were used, they would have to be very long, because these roads are so wide. Note that signals are, of necessity, so far back from the beginning of the intersection, that INDOT installed an extra signal face at the near side.

Two left turn lanes? Three through traffic lanes? Very common in Sacramento. https://www.google.com/maps/@38.678187,-121.271639,3a,75y,23.84h,91.66t/data=!3m4!1e1!3m2!1s75veMmT2waFoX04QvCMpCA!2e0

Three left turn lanes and two through lanes? Sure. https://www.google.com/maps/@38.678187,-121.271639,3a,75y,23.84h,91.66t/data=!3m4!1e1!3m2!1s75veMmT2waFoX04QvCMpCA!2e0

[xcellntbuy]

When I moved to south Florida in early 1998, mast arms were almost universal in Miami-Dade County as a reaction to Hurricane Andrew in 1992.  There were very few mast arms in Broward County to the north and the ones that did exist were isolated in places like Fort Lauderdale Beach Blvd. (FL A1A) and the like.  Broward liked span wires with traffic lights being vertical.  Palm Beach County liked the signal fastened directly to the wire itself.

A program to introduce mast arms began in Broward County about 12 years ago.  It was a slow process, proceeding as funds were available.  New installations or revamped installations were the places that had the first mast arms installed and they tended to be concentrated on the main 6-lane highways throughout the County.

In 2005, Hurricanes Frances, Jeanne and Wilma (in particular) changed all of that.  Of the 1100-plus signalized intersections in the County, nearly 98% were damaged in some form during Hurricane Wilma.  Entire span wire systems were damaged, missing signal heads, spun around backwards, dangled from broken wires remaining on the prestressed concrete transmission poles, blew away or collapsed into the roadways.    Piles of broken traffic lights could found at almost every intersection.  The same destruction occurred in Palm Beach County where span wires remained common.

In addition, in early 2005, Broward County had just converted all the red and green signals to LED lamps, the yellow LEDs would come later.  To this day, many Broward intersections have a combination of incandescent and LED lamps, different colored partial back plates, black housing and can have an occasional dark green or even yellow signal head.

Mast arm installations have been stepped up dramatically since the last major hurricane season nine years ago and the traffic light system will be in better shape the next time around.

[roadman65]

Florida also uses span wire with a thin cable on top with another cable below it that carries the conduits for the electrical power.  Also Florida uses a small black box where the signal head is fastened that others who maintain span wire assemblies have a visible clamp except in St. Pete.  The city signals using span wire follow the other state's method.  Also Florida uses concrete poles to have the span wires attached to which others either use metal poles or telephone poles particularly in both Carolinas.

New York to keep the signal heads the same height have long arms extending down from the span wire as they like to droop the wire. 

[Roadrunner75]

I am seeing them slowly pop up in New Jersey, such as at this location:
https://www.google.com/maps?ll=40.045021,-74.086309&spn=0.000004,0.00327&t=m&z=19&layer=c&cbll=40.045003,-74.086658&panoid=-zGVljr9P5qFwIxh07dQMA&cbp=12,274.16,,0,3.99 
I hope this is not the start of a trend.

[DSS5]

They can create a problem up here in the mountains when it gets very windy by blowing the signals around. In blowing snow the last thing you want is drivers seeing red and green lights at the same time.

[theline]

Here's a recent span wire installation in Indiana that I think is a real mess: https://www.google.com/maps/@41.698566,-86.137476,3a,75y,90t/data=!3m4!1e1!3m2!1sU6muZcnACud09s88yoQMjQ!2e0?hl=en

I'm not sure if there is a good solution to this, though I'd like to hear your ideas. If mast arms were used, they would have to be very long, because these roads are so wide. Note that signals are, of necessity, so far back from the beginning of the intersection, that INDOT installed an extra signal face at the near side.

Two left turn lanes? Three through traffic lanes? Very common in Sacramento. https://www.google.com/maps/@38.678187,-121.271639,3a,75y,23.84h,91.66t/data=!3m4!1e1!3m2!1s75veMmT2waFoX04QvCMpCA!2e0

Three left turn lanes and two through lanes? Sure. https://www.google.com/maps/@38.678187,-121.271639,3a,75y,23.84h,91.66t/data=!3m4!1e1!3m2!1s75veMmT2waFoX04QvCMpCA!2e0

I think that SR-331 has two left turn lanes, two right turn lanes (there should be two right-only signs), and two through lanes.

As some have suggested, INDOT could have placed poles for masts in the median. They also could have built islands separating through traffic from right turns. Posts on the islands could have also supported masts. I'm sure they were trying to stretch the Major Moves money. You've got to give them credit for making that pay for a lot of projects.

[roadman65]

They can create a problem up here in the mountains when it gets very windy by blowing the signals around. In blowing snow the last thing you want is drivers seeing red and green lights at the same time.

I have seen Colorado use them in towns high up in the Rockies.  In fact I was impressed with the fact they used them that far west as they are usually used in the east.

[cpzilliacus]

OK, so I've lived in California for 85% of my life, so pardon if I sound strange, but I was reading thread    
Traffic Signals Now Controlled By Stop Signs , and I noticed how many signals are just hanging by cables. To my eyes, that's unusual, as traffic signals around here are, almost without exception, handing within steel "standards" (I'm sure someone will correct me). I can look at the Sacramento climate records, and the high temperatures would probably bake the cables around here. Plus, the building code requires that buildings withstand a 70mph wind which has happened several times in Sacramento. Yet, I see signals hanging in states which are known to be hit by hurricanes in the past hanging by wires.

Can someone enlighten me on this?

Maryland and Virginia frequently install traffic signals on span wires, at least at state-maintained intersections. 

The District of Columbia almost never installs signals on span wires, except if the installation is of a temporary nature.

[freebrickproductions]

ALDOT is a big fan of span wires. Almost every intersection they maintain uses them. Huntsville, Mobile, Birmingham, Montgomery, Dothan, Florence, Sheffield, Tuscumbia, and Athens (all of these are in Alabama) all use plenty of spanwires as well.