Origin of Mast-Arm mounted traffic signals

[Roadgeek2500]

I would like to know, why in Pennsylvania the Southeastern Counties never used span wiring at all, when the rest of PA used them as the norm up until the 1980's?   Considering signal types are a state thing (although NYC and Chicago have their own style that differs from the state they're in however it is still consistent as being restricted to a specific jurisdiction), you would figure that all of PA would have the same as SE PA has nothing less in common with the rest of the state.  However, they did not and still do not as I have seen span wires  still installed elsewhere in the Commonwealth up till today.

Sorry to quote such an old post, but I've seen several, Here's an example on PA-3 in Chester County:
https://www.google.com/maps?ll=39.966522,-75.52135&spn=0.000016,0.011362&t=h&z=17&layer=c&cbll=39.966511,-75.523242&panoid=c3TtxuOkAnB-RQlcKJk-sg&cbp=12,86.59,,0,-6.31

[traffic light guy]

Unlike the rest of Pennsylvania, Philly was kind of a late hitter. They installed their first mast-arms during 1974 and 1975. The installations included traffic signal brands such as Eagle flatbacks, Crouse-Hinds Type Rs, and Econolite bullseyes. Although the Flatback had already ceased production at the time, they had many leftovers in the storage units, that were ready to be installed. Broad Street was completely outfitted with mast-arms by the summer of 1975. Unfortunately, as of now, most of these 1974/1975 mast-arm setups have been replaced by modern equipment.
However, I saw a few remaining sets of old 12" mast-supported Eagle flatbacks in the very nothern tip of broad steet, possibly installed in the Spring or Summer of 1975, or possibly as early as 1974 or 1973.

[Amtrakprod]

That's an interesting question, but it may depend on the state.  I'm sure some states didn't use span wire at all, or rarely.  California  and Illinois come to mind as states where I've never encountered span wire except in construction zones, though I could be mistaken. 

In Virginia, span wire installations made up the majority of signal assemblies installed before the early 1990s. This time period marked a paradigm shift in using mast arms instead, though there were mast arms installed long before 1990.  Occasionally, permanent span wire installations are still erected in VA.  Most recently (2011 or so), a new span wire was installed by VDOT on SR-784/Dale Blvd in Dale City at a fire station.

I found a wire permanent signal in Illinois: https://www.google.com/maps/@40.6828226,-89.606248,3a,25.3y,238.73h,94.93t/data=!3m6!1e1!3m4!1s19dEY61itGHIpad7nkORwQ!2e0!7i13312!8i6656

[dbz77]

I'm pretty sure California had mast arms before the 1950s. I'll have to find a photo showing this on one of the California roads Facebook groups I frequent. They were in wide use at my earliest memories, and unless they were all installed in the first five years or so of my life, they were in use in the 1940s and maybe even before. The California mast arm design for many years was an 8-8-8 head on a double guy wire-supported arm. This was used until the 1960s when the first monotube arms were deployed.

I am guessing they were used at busy rural intersections.

It was niot until the mid-1960's that the Los Angeles area used mast arms.

[cl94]

I'm sure some states didn't use span wire at all, or rarely.  California  and Illinois come to mind as states where I've never encountered span wire except in construction zones, though I could be mistaken.

There used to be a span wire signal at the intersection of Foothill Blvd and Voss Ave in Cupertino, CA but it was removed more than a decade ago and replaced with a modern mast arm.

As of May, Fresno had a permanent span wire signal at Broadway and Mono, just southeast of the baseball stadium. That remains the only permanent span wire signal I have seen in CA. Even 4-way flashers are often on mast arms in California.

Nevada has also been using mast arms forever. Similar to California, Nevada once used guy wire mast arms of the type still used in New York City. Most of these are gone at this point (having been replaced by more modern styles), but a handful still exist around the state. I will note that Nevada has nonzero 4-way flashers on span wire (even along state roads), with Virginia City and Battle Mountain each being home to examples. I have never seen a permanent 3-color signal on span wire in Nevada.

[dbz77]

I'm sure some states didn't use span wire at all, or rarely.  California  and Illinois come to mind as states where I've never encountered span wire except in construction zones, though I could be mistaken.

There used to be a span wire signal at the intersection of Foothill Blvd and Voss Ave in Cupertino, CA but it was removed more than a decade ago and replaced with a modern mast arm.

As of May, Fresno had a permanent span wire signal at Broadway and Mono, just southeast of the baseball stadium. That remains the only permanent span wire signal I have seen in CA. Even 4-way flashers are often on mast arms in California.

Nevada has also been using mast arms forever. Similar to California, Nevada once used guy wire mast arms of the type still used in New York City. Most of these are gone at this point (having been replaced by more modern styles), but a handful still exist around the state. I will note that Nevada has nonzero 4-way flashers on span wire (even along state roads), with Virginia City and Battle Mountain each being home to examples. I have never seen a permanent 3-color signal on span wire in Nevada.

In the 1930's, Nevada was using span wire installation like these ones in ely, near the Hotel Nevada.

[US 89]

Span wire used to be everywhere in Utah, but since maybe 1990 or so a wholesale switch to mast arms has occurred.

If you know where to look, you can find span wire signals in the state, but they are few in number and rapidly being replaced by mast arms. Probably less than 30 remain at this point, the vast majority of which are on locally maintained streets in Salt Lake City.

[andrepoiy]

Looking at some historic photographs of Toronto, signals (which used to be mounted on the side of the road) started to get mounted hanging over the road between 1950 and 1960.

Here's a comparison:

[JoePCool14]

That's an interesting question, but it may depend on the state.  I'm sure some states didn't use span wire at all, or rarely.  California  and Illinois come to mind as states where I've never encountered span wire except in construction zones, though I could be mistaken. 

In Virginia, span wire installations made up the majority of signal assemblies installed before the early 1990s. This time period marked a paradigm shift in using mast arms instead, though there were mast arms installed long before 1990.  Occasionally, permanent span wire installations are still erected in VA.  Most recently (2011 or so), a new span wire was installed by VDOT on SR-784/Dale Blvd in Dale City at a fire station.

I found a wire permanent signal in Illinois: https://www.google.com/maps/@40.6828226,-89.606248,3a,25.3y,238.73h,94.93t/data=!3m6!1e1!3m4!1s19dEY61itGHIpad7nkORwQ!2e0!7i13312!8i6656

Looks like this one's been replaced.