Traffic Lights

gafftapegreenia

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Ok, random yes, but they do have some theatrical ties:
All questions refer to American-style, traditional, 3 color, incandescent, non-LED traffic lights.

What are the two common diameters of traffic lights available?

What type of reflector is used in a traffic light?

What type of glass lenses are commonly used? (I'm looking for a more blanket term here, as there are several different varieties of lenses from the past and the present, however, for reference, there are about 2-3 dominant styles)

What is the official name for the "blue green" color seen on some traffic lights? Where did this color originate and why was it needed?

What might we call the two styles of visors found on traffic lights in the theatrical world?

Before LED's, how was the "green arrow" produced?

Well, have at 'em.
 
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jonhirsh

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What are the two common diameters of traffic lights available?
im going to guess 11" or 12" and 6" to 8"

What is the official name for the "blue green" color seen on some traffic lights? Where did this color originate and why was it needed?

- i have never seen that before.

What might we call the two styles of visors found on traffic lights in the theatrical world?

-Top Hats?
- Barndoors?

Before LED's, how was the "green arrow" produced?
Well, have at 'em.
-it was black painted on the glass leaving the arrow shape unpainted.
 

gafftapegreenia

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Yes, the two standard sizes are 8" and 12".

The arrow was indeed painted on the lens.

Traffic lights today have full visors, and many of the older ones had "cut-away" visors. We might call these top-hats and half-hats.

Good job so far.

Some green lenses are a more "primary green", while some are a "blue green". Again, why this blue-green color and where did it originate?
 

Charc

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Yes, the two standard sizes are 8" and 12".
The arrow was indeed painted on the lens.
Traffic lights today have full visors, and many of the older ones had "cut-away" visors. We might call these top-hats and half-hats.
Good job so far.
Some green lenses are a more "primary green", while some are a "blue green". Again, why this blue-green color and where did it originate?
In the city of Philly we have a mustard yellow color. Not to say I haven't traveled, but I've not ever paid an extreme amount of attention to the color of traffic lights in other cities...:rolleyes:

I have noticed, recently, I believe I was in Hartford, a black oval with white stripes surrounding the traffic signal... I'm not sure why.
 

gafftapegreenia

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Interesting. While my topic is concerned to the actual optics of a traffic light, there are actualy many collectors out there with literally hundreds of traffic lights, and they pay top dollar for rare or old ones. So you see, those of us who love the old lighting instruments are quite normal. :)

The black ovals that surround traffic lights are to block out background light, thus increasing visibility by seperating the traffic light from the surrounding enviroment.
 

Charc

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Interesting. While my topic is concerned to the actual optics of a traffic light, there are actualy many collectors out there with literally hundreds of traffic lights, and they pay top dollar for rare or old ones. So you see, those of us who love the old lighting instruments are quite normal. :)
The black ovals that surround traffic lights are to block out background light, thus increasing visibility by seperating the traffic light from the surrounding enviroment.
Philly can't pay for black ovals. We can't stop the unbelievable murder rate either... :rolleyes:

(Speaking of murder rate... my school is in the middle of a not so nice neighborhood. In fact the drama teacher at the public high school around the corner had his neck broken when he confiscated a students iPod. I, and a number of other friends and classmates have gotten jumped. I always lock my car doors while driving around school.)
 
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Van

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Some green lenses are a more "primary green", while some are a "blue green". Again, why this blue-green color and where did it originate?
The only thing I know about glass is that you get blue-green from altering the Selenium content, don't ask me how I know, it just got stuck in there. So is it "selenium-Green" ?
 

gafftaper

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My guess is that they added the blue to the green to help people who are color blind.



Oh and the school I taught at was tougher than yours Charc. There was a drive by shooting of the bus stop across the street from the school, when her daughter was busted for being in a fight a mom came to school and beat up the security guy-mom & daughter left in cuffs together, there was the day we were locked down because a dangerous guy escaped from the minimum security mental institution down the street, and finally they found a dead body on the running track one morning before school. Ahh how I miss the good old days!
 

Charc

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My guess is that they added the blue to the green to help people who are color blind.
Oh and the school I taught at was tougher than yours Charc. There was a drive by shooting of the bus stop across the street from the school, when her daughter was busted for being in a fight a mom came to school and beat up the security guy-mom & daughter left in cuffs together, there was the day we were locked down because a dangerous guy escaped from the minimum security mental institution down the street, and finally they found a dead body on the running track one morning before school. Ahh how I miss the good old days!
Haha, touché Gaff, touché. It may be tougher, but it's still annoying having to look over your shoulder. Especially 'cause we're seen as the obnoxious rich kids, we get a lot of verbal confrontations, threats, etc.

Oh to the blue green. You might the green traffic light? I thought you might the instrument as a whole. I didn't mean to imply we have yellow-green signals.
 

Charc

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My guess is that they added the blue to the green to help people who are color blind.
Oh and the school I taught at was tougher than yours Charc. There was a drive by shooting of the bus stop across the street from the school, when her daughter was busted for being in a fight a mom came to school and beat up the security guy-mom & daughter left in cuffs together, there was the day we were locked down because a dangerous guy escaped from the minimum security mental institution down the street, and finally they found a dead body on the running track one morning before school. Ahh how I miss the good old days!
P.S.

Wasn't your school also the one with the special ed puppets hung in a noose in the proscenium wall?
 

gafftapegreenia

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The colored blind reason is mainly the reason why the color is still used.
However, it's not why this color was created originally. Why would a company such as KOPP offer blue-green lenses? What industry is KOPP historically known to make lenses for? Think about the earlier uses of lenses and different illumination sources.
 
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jonhirsh

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Lol are you insinuating that KOPP had an extra supply of bluish green Roundels just sitting around so they sold them to the trafic light industry?

Something about that seems kinda wrong to me :) I would hazard to guess that the trafic light industry let us use there technology....
JH
 

gafftapegreenia

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Lol are you insinuating that KOPP had an extra supply of bluish green Roundels just sitting around so they sold them to the trafic light industry?
Something about that seems kinda wrong to me :) I would hazard to guess that the trafic light industry let us use there technology....
JH
Not at all. Blue-green was in use before traffic lights.
 

dvsDave

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Oddly enough, I've got a real decommisioned traffic light from the 60's that I've been meaning to convert to a DMX interface for about 3 years now.

Add in the lights, fit an internal power pack and DMX interface and create a versatile mounting system for rigging the light.

If anybody is interested, I can see about providing pictures and dimensions.

-David
 

gafftapegreenia

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Ah, Dave, that's awesome. I've been wanting to do something light that. I think that, as an instrument, traffic lights have underutilized design possiblities. Can you imagine a whole rig of traffic lights circuited to do chases and patterns? I think it would be pretty awesome. One better would be to retrofit some RGB LED heads into the housing, put in clear lenses and then wham, color mixing in some awesome housing.
 

gafftaper

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Wasn't your school also the one with the special ed puppets hung in a noose in the proscenium wall?
That is correct. As far as I know Timmy and Jimmy are still hanging 20 feet in the air... I couldn't figure out how to get them down safely so I left them.

There was nothing quite as fun as teaching in a school where you knew there was a good chance that several knives and a gun were possibly in your class room. One day while I was teaching in my theater I suddenly smelled weed. I got to the lobby just in time to see the emergency exit door close. Someone had just stopped in to smoke some pot in the theater lobby. It was an "interesting place".

Sorry Hijack ends...

I find this discussion of traffic lights oddly fascinating. I've never taken the time to think about them before that much. But it's very intriguing. I eagerly wait for my gaff-brother's answers.
 
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gafftapegreenia

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I have been enjoying this thread as well. No one has has yet come up with the name for the blue-green glass, but here's what I'll give.

The blue-green predates traffic lights. It was first used on the railroads. Why did they need this blue green color? Again, consider illumination sources. (This should help, and I'm not going to say it's proper name -yet- that would give it away)

As most traffic lights are being converted to LED's, the days of lamps, reflectors and glass lenses are drawing to an end. The lense one is tough, but I won't give it till the color question is answered.

Any thoughts on reflector style?
 

gafftaper

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So is the glass left over from the lanterns that the switching guys would wave on the railroads... Sorry my railroad knowledge is weak but I have this image in the back of my mind of a man waving a small hand held lantern about the size of an 8" fresnel. Some sort of oil lantern?

I'm guessing the reflector is some variation of on a Parabolic reflector... it seems like the parallel lines of light coming out of the reflector would be a good thing.
 

gafftapegreenia

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The reflector is parabolic. So, theres another question down there.

Don't get hung up over the shape of the lens. What's important here is the significance of the blue-green glass in relationship to a non-electric light source.