Double-guy Mast Arm attachments.

[steviep24]

Crosspost from the "Traffic Signal" thread:

i came across these signals in downtown Buffalo, NY today. These are not that old but have guy wires on the mast arms for some reason.

https://www.google.com/maps/@42.9022056,-78.8706533,3a,75y,275.48h,90t/data=!3m6!1e1!3m4!1sG3JC0u_HrpxOLHZpkVbFtA!2e0!7i13312!8i6656?hl=en&authuser=0

https://www.google.com/maps/@42.9022132,-78.8711792,3a,75y,261.77h,99.15t/data=!3m6!1e1!3m4!1svR5MrkdwkB9hj6-fdgWbZQ!2e0!7i13312!8i6656?hl=en&authuser=0

Most signals in Buffalo use straight mast arms without the guy wire supports or are on span wire.

EDIT: After looking at old Google Steetview these were installed sometime after 2007.

[mrsman]

McDowell/44th:  The new signals definitely look very sturdy and professional, but to me I just think there are more signal heads than necessary.  For a dual left turn lane, there are two left singal heads on the mast and one of the streetlight on the left corner.  And for 3 thru lanes, there are three overhead signal heads on the mast and one on the streetlight.  To me this is overkill.

As I mentioned earlier, I like the old California style.  I would have one left turn signal on the mast and one on the streetlight.  One thru signal on the streetlight, and at most two thru signals on the mast.

[The old CA style would have only one thru signal on the mast, but I can admit that this is a wide street so two signal heads may be appropriate, but not 3.]

If I had to generalize rules for appropriate signal head placement, I would say:

Two signal faces for every unique signalized movement, period.  Regardless of the movement.

If there are no special signals for turns, there should be a signal face at left corner, and one at the right corner.  If there are X thru lanes, there should also be X-1 signals on the mast.  [0 mast signals for one thru lane, 1 mast signal for 2 thru lanes, 2 mast signals for 3 thru lanes etc.]  Exception: 1 thru lane and 1 left turn lane will also include 1 signal on the mast.

If there are also signals for right turn movements that also contain the thru movement (doghouse, 5 aspect straight line), the signal face at the right corner should also have the right turn signal aspect.  There should also be a near side signal face that is equivalent.

If there are also signals for right turn movements that are unique (FYA or RA-YA-GA), one should be on the near side corner and one should be on the far side right corner.  But be sure to maintain at least two signals for the straight movement, so this may require an additional straight signal on the mast.  [These signals are relatively rare, and usually only used when there are heavy pedestrian movements.]

If there are also signals for left turn movements that also contain the thru movement (doghouse, 4 aspect straight line, 5 aspect straight line), the signal face at the far left corner should also have the left turn signal aspect.  The left most signal on the mast should also have a left turn signal aspect. 

If there are also signals for left turn movements that are unique (FYA or RA-YA-GA), one should be on the far left corner and one should be on the mast.  But be sure to maintain at least two signals for the straight movement, so this may require an additional straight signal on the mast.  (If there are theree or more left turn lanes, an additional left turn signal on the mast is appropriate).

For your third-to-last suggestion (unique right turn signal), I agree with your suggestions, except that a second pole-mounted signal could be used on the far-side of the intersection. They could be placed right next to each other, perhaps appearing as one giant 6- (or 7-) face signal.

I think we would get along very nicely! I agree with all of your suggestions. CA has managed to figure out a remarkable feat: signalizing massive intersections (20-30 approach lanes) without having them appear too cluttered. Good signal spacing, backplates (so the signals don't get lost), two signals for every movement, overhead signals using through-minus-one as a base (though there are plenty with only one overhead for three approach lanes; hell, I've seen one overhead for four through lanes!), and so on. Very impressive attention to detail.

I don't know of any state that signalizes their intersections like California. CO is probably the closest, in that they often drop a second left turn signal overhead, in favor of having a second on the left-pole. Every other (AZ, NV, MN, IL) seems to have adopted signal-per-lane strategies; nothing wrong with this per-se, but I don't know how necessary it is to have what can only be described as, perhaps, overkill, at some intersections in places like Nevada (though to be clear, this is still way better than MUTCD-standard placement, which is god-awful).

Off-topic: you may like this intersection in Spokane, WA. It has four examples of double-left turns that swap having two overhead left turn signals, for one overhead and one on the left. The supplemental signals also don't use backplates, which I personally prefer (reducing clutter). Plus, they use through-minus-one for signal placement.

I have to admit that my bias for this type of traffic signal is because I grew up in Los Angeles.  This was of course the standard of the signals of that era (1970's and 1980's).  And of course they made healthy use of double guy mast arms.  IMO, that's sufficient without being wasteful.  However, these days many newer installations are incorporating signal per lane in some areas of the state.

Here's a classic at Olympic and Prosser in West L.A.  Westbound there are 4 lanes of traffic* plus a left turn lane.  Yet only 3 signal faces.  Double guy mast arm.  The signals on Prosser got upgraded from 8-8-8 to 12-12-12, but the signals on Olympic haven't been changed in 50 years and IMO don't need to be.

https://www.google.com/maps/@34.048256,-118.4243816,3a,75y,234.33h,85.15t/data=!3m6!1e1!3m4!1sJm_ClrMmR-Lt8qnG2NL5Bg!2e0!7i16384!8i8192


Generally it is better to have too many signal faces rather than too few.  As you sometimes visit this area, you know that in Northern Virginia and Suburban Maryland post-mounted signals are rare, as these are areas that usually incorporated span wire until the recent past.  THey simply replaced the span wire with masts, but kept the signal at the same height, over the center of the street.  Both signal heads get blocked if you're behind a truck or bus.  And when making a permissive left turn, I find that I have to constantly turn my head from the signal to the corner to find a safe time to turn.  The left corner signal face is really useful, too bad that only a handful of states mandate it!

[DC has the opposite problem.  Pole mounted signals at every intersection, but even very wide streets do not have mast arms, or have very short mast arms.  I find the signals there to be quite weird.]

There is a downside to having too many signal faces.  First, you're wasting taxpayer money.  Second, to the extent that intersections are placed close together, you could have the problem that drivers may not know which signal if meant for them.  Utilizing 3m signals or louvers can help to block out the further signal, but not every place uses them.

* Three lanes of traffic with fourth Lane available doing afternoon Rush hour.  Realistically very few people Park here and the 4th Lane is generally always use for traffic.   I am still not convinced as to how I should treat Rush hour Lanes with regards to the x-1 rule above.  I think I will treat it as a moving lane under most circumstances.

One *minor* nitpick from me, and that is that beginning in the 1970s, I don't recall seeing any of the guy-wired mast arms being installed. I believe those were phased out in the late 60s. My memory goes back as far as 1974, when a traffic ight was installed using mast arms near where I was living at the time (at Culver & Walnut in Irvine), and most of the guy-wired installations I was seeing at the time already looked like they'd been around for years.

There is a natural time lag to some of these things.  Given my age, I was born in 1975, but don't really remember stuff before the early 1980's.  So even if at that point, no more new guy-wired signals were installed (and that might be correct in L.A. city proper), you could still have so many signals from the earlier era in place and doing well, that in fact the majority of the signals were from the earlier era.  In the 1980's., the vast majority of existing signals in L.A. had guy-wire even if no new signal had it.

Of course, the suburban areas, that I am familiar with, tended to have fewer instances of guy-wire, than L.A. proper.   

A similar issue with the time lag exists with the cars themselves.  In the early 1980's, there were far more older cars built in the 1960's and 1970's then newer cars that were built in that decade.  Likewise, most of the cars in the 1980's tended to have the blue license plates with six digits (123 ABC), even when the newer cars had white license plates and 7 digits (1ABC123).

So in short, you may be right that when I came of age, the new signals in L.A. no longer installed guy-wire signals (I have no idea when they stopped), but it is also true that the vast majority of signals that I encoutered followed the format that I described upthread, even if they may have been installed in the 1960's.

[jakeroot]

One *minor* nitpick from me, and that is that beginning in the 1970s, I don't recall seeing any of the guy-wired mast arms being installed. I believe those were phased out in the late 60s. My memory goes back as far as 1974, when a traffic ight was installed using mast arms near where I was living at the time (at Culver & Walnut in Irvine), and most of the guy-wired installations I was seeing at the time already looked like they'd been around for years.

Do you know if the signals that are at that intersection today are the same as the ones that were installed in the 1970s? I can see from Historic Aerials that the intersection looks the same in 1980 as it does today, but I don't know when that intersection was rebuilt in the 70s.

Street View link

[Mark68]

One *minor* nitpick from me, and that is that beginning in the 1970s, I don't recall seeing any of the guy-wired mast arms being installed. I believe those were phased out in the late 60s. My memory goes back as far as 1974, when a traffic ight was installed using mast arms near where I was living at the time (at Culver & Walnut in Irvine), and most of the guy-wired installations I was seeing at the time already looked like they'd been around for years.

Do you know if the signals that are at that intersection today are the same as the ones that were installed in the 1970s? I can see from Historic Aerials that the intersection looks the same in 1980 as it does today, but I don't know when that intersection was rebuilt in the 70s.

Street View link

I believe the installations with the 3M left turn signals and more faded street signs are the originals. So those would be the ones on the south and west corners (the streets in this area of OC are arranged at an angle roughly parallel to or perpendicular from the coast). The one on the north corner is new(er), maybe from the 80s or early 90s (I had left that area by then) and the one on the east corner looks pretty new.

[mrsman]

One *minor* nitpick from me, and that is that beginning in the 1970s, I don't recall seeing any of the guy-wired mast arms being installed. I believe those were phased out in the late 60s. My memory goes back as far as 1974, when a traffic ight was installed using mast arms near where I was living at the time (at Culver & Walnut in Irvine), and most of the guy-wired installations I was seeing at the time already looked like they'd been around for years.

Do you know if the signals that are at that intersection today are the same as the ones that were installed in the 1970s? I can see from Historic Aerials that the intersection looks the same in 1980 as it does today, but I don't know when that intersection was rebuilt in the 70s.

Street View link

I believe the installations with the 3M left turn signals and more faded street signs are the originals. So those would be the ones on the south and west corners (the streets in this area of OC are arranged at an angle roughly parallel to or perpendicular from the coast). The one on the north corner is new(er), maybe from the 80s or early 90s (I had left that area by then) and the one on the east corner looks pretty new.

That makes a lot of sense.  I don't recall guy-wires in Irvine at all.  Then again, the land around Irvine was really developing and booming during the 1970's and 1980's, unlike central L.A. which was pretty developed since the 1920's and 1930's (or more northern parts of OC like Anaheim which developed largely in the 1950's and 1960's).  I wouldn't doubt that it was during the 1960's and 1970's that 2 lane rural roads were converted to 6 lane behemoths with double left turn lanes at each intersection.  And that being the case,

The standard for double left turns (and other protected only lefts) in those days was a R-Y-GA or R-YA-GA signal, with some kind of hiding of the red (3M or louver) to not confuse thru traffic.  The curved mast arms were at that time state of the art (the older design had the left arrow signal on an 8-8-12 in the median).  The curved mast arms were strong enough for two overhead signals, one for straight traffic and one for left turns.

Having more than one overhead signal for straight movements in CA, even on a wide street, is a very recent development.

[Mark68]

One *minor* nitpick from me, and that is that beginning in the 1970s, I don't recall seeing any of the guy-wired mast arms being installed. I believe those were phased out in the late 60s. My memory goes back as far as 1974, when a traffic ight was installed using mast arms near where I was living at the time (at Culver & Walnut in Irvine), and most of the guy-wired installations I was seeing at the time already looked like they'd been around for years.

Do you know if the signals that are at that intersection today are the same as the ones that were installed in the 1970s? I can see from Historic Aerials that the intersection looks the same in 1980 as it does today, but I don't know when that intersection was rebuilt in the 70s.

Street View link

I believe the installations with the 3M left turn signals and more faded street signs are the originals. So those would be the ones on the south and west corners (the streets in this area of OC are arranged at an angle roughly parallel to or perpendicular from the coast). The one on the north corner is new(er), maybe from the 80s or early 90s (I had left that area by then) and the one on the east corner looks pretty new.

That makes a lot of sense.  I don't recall guy-wires in Irvine at all.  Then again, the land around Irvine was really developing and booming during the 1970's and 1980's, unlike central L.A. which was pretty developed since the 1920's and 1930's (or more northern parts of OC like Anaheim which developed largely in the 1950's and 1960's).  I wouldn't doubt that it was during the 1960's and 1970's that 2 lane rural roads were converted to 6 lane behemoths with double left turn lanes at each intersection.  And that being the case,

The standard for double left turns (and other protected only lefts) in those days was a R-Y-GA or R-YA-GA signal, with some kind of hiding of the red (3M or louver) to not confuse thru traffic.  The curved mast arms were at that time state of the art (the older design had the left arrow signal on an 8-8-12 in the median).  The curved mast arms were strong enough for two overhead signals, one for straight traffic and one for left turns.

Having more than one overhead signal for straight movements in CA, even on a wide street, is a very recent development.

Yeah, Irvine incorporated in 1971 and we moved there in '72. At the time, the northeast side of Walnut (basically the entire area between Walnut, I-5, Jeffrey Rd & Culver Dr) was all orange groves and the house my parents bought was a new build near the railroad tracks at (what was then) the end of Yale. I believe the only traffic lights in the entire city at the time were maybe at Sand Canyon/Trabuco (the main entrance to USMC El Toro), and maybe areas to the southwest of the 405, along Culver, University & Campus Drives (near UCI).

Walnut was two lanes for most of its length between Jeffrey Rd and its dead end at Harvard. Culver was 4 lanes SW of I-5. For the first couple of years, we had to go to Tustin for groceries until they built a Safeway (which is now the Whole Foods) at Culver/Walnut. That's about the time the light was installed. I believe Tustin is also where the closest guy wires were (on Red Hill).


Irvine HS opened up on Walnut in 1976, and that's when Walnut began to be widened to 4 lanes. We moved to NE Anaheim in 1978, east of the 57. We lived near Lincoln/Rio Vista, and that intersection had a light with Lincoln having relatively new mast arms (probably around the time the 57 opened) and Rio Vista having guy wires. It was the same setup on the other side of the freeway, at Lincoln & Sunkist.

[dbz77]

One *minor* nitpick from me, and that is that beginning in the 1970s, I don't recall seeing any of the guy-wired mast arms being installed. I believe those were phased out in the late 60s. My memory goes back as far as 1974, when a traffic ight was installed using mast arms near where I was living at the time (at Culver & Walnut in Irvine), and most of the guy-wired installations I was seeing at the time already looked like they'd been around for years.

Do you know if the signals that are at that intersection today are the same as the ones that were installed in the 1970s? I can see from Historic Aerials that the intersection looks the same in 1980 as it does today, but I don't know when that intersection was rebuilt in the 70s.

Street View link

I believe the installations with the 3M left turn signals and more faded street signs are the originals. So those would be the ones on the south and west corners (the streets in this area of OC are arranged at an angle roughly parallel to or perpendicular from the coast). The one on the north corner is new(er), maybe from the 80s or early 90s (I had left that area by then) and the one on the east corner looks pretty new.

That makes a lot of sense.  I don't recall guy-wires in Irvine at all.  Then again, the land around Irvine was really developing and booming during the 1970's and 1980's, unlike central L.A. which was pretty developed since the 1920's and 1930's (or more northern parts of OC like Anaheim which developed largely in the 1950's and 1960's).  I wouldn't doubt that it was during the 1960's and 1970's that 2 lane rural roads were converted to 6 lane behemoths with double left turn lanes at each intersection.  And that being the case,

The standard for double left turns (and other protected only lefts) in those days was a R-Y-GA or R-YA-GA signal, with some kind of hiding of the red (3M or louver) to not confuse thru traffic.  The curved mast arms were at that time state of the art (the older design had the left arrow signal on an 8-8-12 in the median).  The curved mast arms were strong enough for two overhead signals, one for straight traffic and one for left turns.

Having more than one overhead signal for straight movements in CA, even on a wide street, is a very recent development.

Yeah, Irvine incorporated in 1971 and we moved there in '72. At the time, the northeast side of Walnut (basically the entire area between Walnut, I-5, Jeffrey Rd & Culver Dr) was all orange groves and the house my parents bought was a new build near the railroad tracks at (what was then) the end of Yale. I believe the only traffic lights in the entire city at the time were maybe at Sand Canyon/Trabuco (the main entrance to USMC El Toro), and maybe areas to the southwest of the 405, along Culver, University & Campus Drives (near UCI).

Walnut was two lanes for most of its length between Jeffrey Rd and its dead end at Harvard. Culver was 4 lanes SW of I-5. For the first couple of years, we had to go to Tustin for groceries until they built a Safeway (which is now the Whole Foods) at Culver/Walnut. That's about the time the light was installed. I believe Tustin is also where the closest guy wires were (on Red Hill).


Irvine HS opened up on Walnut in 1976, and that's when Walnut began to be widened to 4 lanes. We moved to NE Anaheim in 1978, east of the 57. We lived near Lincoln/Rio Vista, and that intersection had a light with Lincoln having relatively new mast arms (probably around the time the 57 opened) and Rio Vista having guy wires. It was the same setup on the other side of the freeway, at Lincoln & Sunkist.

Lincoln and Rio Vista, circa 2008.

https://goo.gl/maps/JJoJxfwkBz5SkZjL9

So apparently, the newer mast arms are over forty years old.

(Note that the guy wires are attached to concrete poles, similar to the setup at the entrance to Disneyland in the 1960s.)

It had been replaced since then.

https://goo.gl/maps/q4N6opWENk7iZT7w6

[mrsman]

One *minor* nitpick from me, and that is that beginning in the 1970s, I don't recall seeing any of the guy-wired mast arms being installed. I believe those were phased out in the late 60s. My memory goes back as far as 1974, when a traffic ight was installed using mast arms near where I was living at the time (at Culver & Walnut in Irvine), and most of the guy-wired installations I was seeing at the time already looked like they'd been around for years.

Do you know if the signals that are at that intersection today are the same as the ones that were installed in the 1970s? I can see from Historic Aerials that the intersection looks the same in 1980 as it does today, but I don't know when that intersection was rebuilt in the 70s.

Street View link

I believe the installations with the 3M left turn signals and more faded street signs are the originals. So those would be the ones on the south and west corners (the streets in this area of OC are arranged at an angle roughly parallel to or perpendicular from the coast). The one on the north corner is new(er), maybe from the 80s or early 90s (I had left that area by then) and the one on the east corner looks pretty new.

That makes a lot of sense.  I don't recall guy-wires in Irvine at all.  Then again, the land around Irvine was really developing and booming during the 1970's and 1980's, unlike central L.A. which was pretty developed since the 1920's and 1930's (or more northern parts of OC like Anaheim which developed largely in the 1950's and 1960's).  I wouldn't doubt that it was during the 1960's and 1970's that 2 lane rural roads were converted to 6 lane behemoths with double left turn lanes at each intersection.  And that being the case,

The standard for double left turns (and other protected only lefts) in those days was a R-Y-GA or R-YA-GA signal, with some kind of hiding of the red (3M or louver) to not confuse thru traffic.  The curved mast arms were at that time state of the art (the older design had the left arrow signal on an 8-8-12 in the median).  The curved mast arms were strong enough for two overhead signals, one for straight traffic and one for left turns.

Having more than one overhead signal for straight movements in CA, even on a wide street, is a very recent development.

Yeah, Irvine incorporated in 1971 and we moved there in '72. At the time, the northeast side of Walnut (basically the entire area between Walnut, I-5, Jeffrey Rd & Culver Dr) was all orange groves and the house my parents bought was a new build near the railroad tracks at (what was then) the end of Yale. I believe the only traffic lights in the entire city at the time were maybe at Sand Canyon/Trabuco (the main entrance to USMC El Toro), and maybe areas to the southwest of the 405, along Culver, University & Campus Drives (near UCI).

Walnut was two lanes for most of its length between Jeffrey Rd and its dead end at Harvard. Culver was 4 lanes SW of I-5. For the first couple of years, we had to go to Tustin for groceries until they built a Safeway (which is now the Whole Foods) at Culver/Walnut. That's about the time the light was installed. I believe Tustin is also where the closest guy wires were (on Red Hill).


Irvine HS opened up on Walnut in 1976, and that's when Walnut began to be widened to 4 lanes. We moved to NE Anaheim in 1978, east of the 57. We lived near Lincoln/Rio Vista, and that intersection had a light with Lincoln having relatively new mast arms (probably around the time the 57 opened) and Rio Vista having guy wires. It was the same setup on the other side of the freeway, at Lincoln & Sunkist.

Lincoln and Rio Vista, circa 2008.

https://goo.gl/maps/JJoJxfwkBz5SkZjL9

So apparently, the newer mast arms are over forty years old.

(Note that the guy wires are attached to concrete poles, similar to the setup at the entrance to Disneyland in the 1960s.)

It had been replaced since then.

https://goo.gl/maps/q4N6opWENk7iZT7w6

Absolutely consistent with what I've been saying.  Generally, signal will be built to the state of the art when they are built and only upgraded when necessary.  It is relatively rare to upgrade everything to current standards.  (The only consistent upgrade that I remember was the placing of pedestrian signal heads.  Many guy-wire setups did not have pedestrian signals when originally constructed.  They have them, and those do seem to upgraded more regularly to provide international symbols (hand/walking man) and now countdown timers. The signal faces may get upgraded as well to go from 8-8-8 to 12-12-12 or to somehow account for LED lighting, even if the mast arms are left alone.)

As the area in Anaheim developed in 50's and 60's, the state of the art in CA for a multi-lane street was an 8-8-8 signal on the left, an 8-8-8 signal on the right and a 12-12-12 hanging from a guy-wired mast arm, from the right, and usually on a lamppost.  This served Rio Vista all this time and was only upgraded relatively recently with the addition of a doghouse left turn arrow signal that was placed in addition (instead of replacing) the 12-12-12 on the guy-wired mast arm.

Lincoln probably started with guy wires as well.  By the time Mark68 moved into the area, there was already the need to place a R-Y-GA left turn signal, so it needed upgraded to what was then the state of the art in the 1970's the strong curved mast arm.  (CA guy wires generally only hold one overhead signal, not two).  It seems like that mast arm is still in use today.

The city of L.A. takes a bit longer to upgrade then the surrounding suburbs.  So while it may be rare to find guy-wire in OC today, there are still plenty of examples in L.A. today, but not on any of the newer installs.

[dbz77]

Lincoln and Rio Vista, circa 2008.

https://goo.gl/maps/JJoJxfwkBz5SkZjL9

So apparently, the newer mast arms are over forty years old.

(Note that the guy wires are attached to concrete poles, similar to the setup at the entrance to Disneyland in the 1960s.)

It had been replaced since then.

https://goo.gl/maps/q4N6opWENk7iZT7w6

Absolutely consistent with what I've been saying.  Generally, signal will be built to the state of the art when they are built and only upgraded when necessary.  It is relatively rare to upgrade everything to current standards.  (The only consistent upgrade that I remember was the placing of pedestrian signal heads.  Many guy-wire setups did not have pedestrian signals when originally constructed.  They have them, and those do seem to upgraded more regularly to provide international symbols (hand/walking man) and now countdown timers. The signal faces may get upgraded as well to go from 8-8-8 to 12-12-12 or to somehow account for LED lighting, even if the mast arms are left alone.)

As the area in Anaheim developed in 50's and 60's, the state of the art in CA for a multi-lane street was an 8-8-8 signal on the left, an 8-8-8 signal on the right and a 12-12-12 hanging from a guy-wired mast arm, from the right, and usually on a lamppost.  This served Rio Vista all this time and was only upgraded relatively recently with the addition of a doghouse left turn arrow signal that was placed in addition (instead of replacing) the 12-12-12 on the guy-wired mast arm.

Lincoln probably started with guy wires as well.  By the time Mark68 moved into the area, there was already the need to place a R-Y-GA left turn signal, so it needed upgraded to what was then the state of the art in the 1970's the strong curved mast arm.  (CA guy wires generally only hold one overhead signal, not two).  It seems like that mast arm is still in use today.

The city of L.A. takes a bit longer to upgrade then the surrounding suburbs.  So while it may be rare to find guy-wire in OC today, there are still plenty of examples in L.A. today, but not on any of the newer installs.

Examples from L.A.

https://goo.gl/maps/oa2bxizu6ZyxyK839

A somewhat newer installation.

https://goo.gl/maps/CKcendnizL7wVBVn6

[mrsman]

Correct.  The old standard of double guy mast arm attachments was basically done in the 1950's and 1960's.  And it seems that even many pre-existing signals in the 1950's that were solely attached to poles at the corners (8-8-8 signals far side, both left and right corner) were all upgraded to include an overhead 12-12-12 with double guy mast arms, if the street were wide enough (basically, wider than one lane of traffic in each direction).  But after that point, most signals were left alone (other than the addition of pedestrian signals) unless they were further upgraded and required a stronger mast arm (usually if adding an addition signal head, like for a turn signal).

The state of the art for the signal in the 1970's and 1980's was the moderate width curved mast arm.  New signals (and signal replacements) used this standard.  For the most part, the older guy wires were not replaced.  For whatever reason, most signals in Downtown L.A. were replaced with this standard, and so there are very few guy wires left in Downtown, but here is one a block away from the previous poster's link:

https://www.google.com/maps/@34.0396105,-118.2558098,3a,75y,332.08h,102.68t/data=!3m6!1e1!3m4!1swT1kSbmeGaCwLikvJOBgUg!2e0!7i16384!8i8192

The Bunker Hill section of Downtown uses a different style altogether.  It was probably considered a design element as the whole section of the city got razed in the early 60's to change from a tawny residential area to the main business district for high powered professionals in skyscrapers.  The mast arm extends straight out and does not curve.

https://www.google.com/maps/@34.0510238,-118.2514704,3a,75y,123.14h,89.08t/data=!3m6!1e1!3m4!1s9nqmB1c_WGKjVx0ynEiX8A!2e0!7i13312!8i6656

Of course, the newer installations use much thicker lampposts and much thicker mast arms.  Newer installations on wider streets will almost always have at least two singal faces  (two orb signals or an orb signal and a turn signal) and so requires more strength.  From the same intersection:

https://www.google.com/maps/@34.0509234,-118.2515037,3a,75y,216.03h,101.77t/data=!3m6!1e1!3m4!1sDuOPj6jv54GMXO-9wNszTA!2e0!7i13312!8i6656

Incidentally, there were many various types of lampposts in L.A. over the years.  While I don't know the precise names of all the types, but typically the shorter lampposts that you tend to see in quiet residential areas like Hancock Park do not get fit with signals.  As far as the taller lammpposts, some do and some don't.  Generally the more decorative lammposts do not get fit with signals and any signal has its own post right nearby.  Here, the signal is on its own base and not attached to the "Wilshire twin"

https://www.google.com/maps/@34.0621073,-118.3383999,3a,75y,108.12h,102.61t/data=!3m6!1e1!3m4!1sFQz4SFsnlUH1BVg42XKYpA!2e0!7i16384!8i8192

Yet in other cases, they do attach the lamppost and the signal's lamppost matches the color scheme of the other nearby lampposts.  Here is  a guy-wire signal attached to a "sandy" lamppost.  The other lampposts down the block are also "sandy"

https://www.google.com/maps/@34.062153,-118.338412,3a,75y,349.07h,84.22t/data=!3m6!1e1!3m4!1sta_uqoF03TsZk8RZ0N7jpA!2e0!7i16384!8i8192

[dbz77]

Yet in other cases, they do attach the lamppost and the signal's lamppost matches the color scheme of the other nearby lampposts.  Here is  a guy-wire signal attached to a "sandy" lamppost.  The other lampposts down the block are also "sandy"

https://www.google.com/maps/@34.062153,-118.338412,3a,75y,349.07h,84.22t/data=!3m6!1e1!3m4!1sta_uqoF03TsZk8RZ0N7jpA!2e0!7i16384!8i8192

The Dzsnweyland Resort area used the "sandy" lampposts to hold up the traffic signals by the early 1960's. I wonder why that changed.

The city of Cerritos (which was built from the late 1970's to mid-1980's)used to use the moderate-width curved mast arms attached to sandy poles. An example is here.

https://goo.gl/maps/iWNPKoDAdppGd9j19

https://goo.gl/maps/Jc2dHDeXL6tZuzq5A

Apparently, the sandy poles can not hold a mast arm that could hold two overhead signals, or even one overhead doghouse signal. The two intersections below used to have the sandy poles on all four corners back as late as the early 1990's, but no longer. 

https://goo.gl/maps/eLKtpfTDbiMTDzr89

https://goo.gl/maps/yTf4xzhPmAtgEuna9

[paulthemapguy]

I couldn't resist

Just 2 Guyz