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Thread: LED traffic signals

  1. #1
    Flashaholic* sunspot's Avatar
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    Default LED traffic signals

    O.K. so it's not really a new topic.
    The city of Birmingham, Alabama has been coverting all signals to LED. Today at lunch, I was standing in front of my work place and saw a bucket truck changing the lights at my intersection. "That's cool" I thought. After a few minutes watching I realized I was a flashaholic missing out on a look/see. So I dodged a few autos and walked up to the workmen. "Hey, I like LEDS, can I look at one?". He handed one right over. They are about 11" X 4" and only weigh about 1-2 lbs. The red signal has white LED's with a red cover. The green one has, well, green LED's with a clear cover. They are made by GE. The specs are 120v with 13.3va. I did not get a chance to count the number of LED's but they were spaced about 3/4-1 inch apart.
    Well, there you go. I had a nice time for a first look at the latest and greatest.

  2. #2
    *Flashaholic* James S's Avatar
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    Default Re: LED traffic signals

    Did you notice if they were replacing the yellow light as well? Most of the lights here in richmond are also LED, but thye left the yellow one. I guess that the light is used for such a short time that it's hard to recoup any savings by replacing it.

    The red and green ones though are really bright. So bright that it's painful at night when you're eyes are dark adapted!

    -James

  3. #3
    Flashaholic* star882's Avatar
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    Default Re: LED traffic signals

    "The red signal has white LED's with a red cover."
    Why?
    Red is cheaper.

  4. #4
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    Default Re: LED traffic signals

    yeah, and since not a lot of red is produce from white leds (not as much as blues anyway) so why would they bother down converting it like this. Or is it that they can't find a suitable wavelength of red?

  5. #5
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    Default Re: LED traffic signals

    Originally posted by Nerd:
    yeah, and since not a lot of red is produce from white leds (not as much as blues anyway) so why would they bother down converting it like this. Or is it that they can't find a suitable wavelength of red?
    <font size="2" face="Verdana, Arial">Are you sure they are white? Many red leds are clear, and only appear red when powered. [img]images/icons/smile.gif[/img]

  6. #6
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    Default Re: LED traffic signals

    Here in Portland they are changing them out as well; I personally know the person in charge of the conversion and he has them laying around his house

    The Red just uses a whole bunch of NiChia RED LEDs, which NiChia sells any quan for $0.30 Each

    It would be INCREDIBLY Ineffecient to use a Blue LED to excite a White Phoshor to make White light and then to filter out all the colors except Red

    Thats even worse than using an incandescent bulb to light up a Red filter

    The Green light is a board with 95% of the LEDs Green and 5% Blue - to make the slight BLUE tint that we are used to

  7. #7
    Flashaholic* sunspot's Avatar
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    Default Re: LED traffic signals

    When I looked at the Red signal, it had a Red plastic cover. I could not see if the LED's had a yellowish phoshor dot like the Whites. It was what the worker told me although he may have been an idiot.

  8. #8
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    Default Re: LED traffic signals

    Although the plastic color filters are not needed anymore since the LEDs make the colors directly, they still use them since they seal in the light

    Hopefully, when they realize that the colored filters are not needed anymore, they will replace them with clear plastic

    I have seen both adapters, they are a large round circuit board that is connected to a standard base adapter - so they screw in directly into the standard light bulb socket

    My friend has one in an antique lamp in his living room

  9. #9

    Default Re: LED traffic signals

    The LED traffic lights I've been seeing do not use filters for any of the three colors. Nor do our green lights have any blue in them - you can see the individual LEDs and they are all the same.

    I am also having a hard time believing that any manufacturer would use (relatively expensive) white LEDs with a red filter. This would negate much of the efficiency edge that these lights have over incandescents, not to mention being much more expensive than using (cheap) red LEDs with no filter.

    -LEDhed

  10. #10
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    Default Re: LED traffic signals

    I'm almost positive the red signals do not use white LEDs. I can tell by the pure red color that they are not white behind the lens. From what I remember, in doing so, the light would come through as a pink-ish color rather than a vibrant true red. I agree this would be much more expensive to produce. And like it was mentioned, bright red LEDs are normally clear until lit up. So yeh, im going with the worker idiot thing [img]images/icons/tongue.gif[/img]

    The signals around the corner from me are LED (as well as everywhere else). The green has a clear lens - not sure about the red. I think they are awesome in general.
    Sunset, yea - in the wet streets at night the green reflects all over the place

  11. #11
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    Default Re: LED traffic signals

    Well, here in Bergen County NJ, most, if not all of the yellows are LED as well. They are the InGAN type as they have that familiar "amber" look to them, a deep yellow similar to the coloration of a school bus. In my area, the green incans were the last to go. The green is blindinly bright. There is a very slight blusihness to the green, but NOT cyan.

    Ed.

  12. #12
    Flashaholic* sunspot's Avatar
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    Default Re: LED traffic signals

    When the conversion was announced in the newspaper, it was stated that they would not replace the yellow due to very little run time on that color.
    I have seen these in other city's and the green is almost to bright. At night with rain slicked streets, they are blinding.

  13. #13
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    Default Re: LED traffic signals

    I have always wondered if they would make a good LED lamp, similar to the SureFire KL2.

    Thanks for the description.

    The RED LED's are actually white LED's, with a RED cover.

    I SEE A MOD IN THE MAKING!

  14. #14
    Flashaholic* sunspot's Avatar
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    Default Re: LED traffic signals

    I try to slip off with one. 13.3va. Hell of a flashlight. I may have trouble with the battery.

  15. #15
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    Default Re: LED traffic signals

    ... About that bluish green that most traffic signal lights try to get for their green lights; That's an attempt to work around one type of colorblindness.

    The idea is to use colors that can actually show strong differences to those folks with any of the types of colorblindness (four major types?), and the straight green and bright yellow (as opposed to blue-green and amber) just don't work as well as visual signals for everyone.

    A very complex problem.






  16. #16
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    Default Re: LED traffic signals

    Well, it will not only save electricity (12w vs 66w), it will also save costs, since it most likely costs $100/hr to replace a light bulb

    Cost of two employees and the bucket truck

  17. #17
    Flashaholic* sunspot's Avatar
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    Default Re: LED traffic signals

    Maintenance cost, as stated in my local newspaper, was $8.00 per year for incand and expected to drop to $0.50 for LED. They did not say if that cost was per bulb or per signal.

  18. #18
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    Default Re: LED traffic signals

    Originally posted by e=mc²:
    Well, here in Bergen County NJ, most, if not all of the yellows are LED as well. They are the InGAN type as they have that familiar "amber" look to them, a deep yellow similar to the coloration of a school bus. In my area, the green incans were the last to go. The green is blindinly bright. There is a very slight blusihness to the green, but NOT cyan.

    Ed.
    <font size="2" face="Verdana, Arial">Do you want a good laugh, e=mc2?

    Here in Bergen County the newspaper reported that they were changing to LED's ONE BULB AT A TIME. That means that when the green incandescent burns out in a light they have the guys go over and replace ONLY the green one!

    It seems obvious to me that it would be much more efficient to replace ALL THREE COLORS during the same (expensive) service call. It would also be safer for the workers because they would only have to set up the orange cones, bring in the police, and stop traffic once for each light, rather than doing it over and over again.

    I'm guessing that they do this because of the cost difference. It is more expensive to change all of the lights to LED's simultaneously and they are only interested in short term costs, not long-term savings (in money and lives).---Marc

  19. #19
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    Default Re: LED traffic signals

    I remember in College (my degree is in Hotel Restaurant Mgt), the prof. told us that it is cheaper to change all the light bulbs in an auditorium at one time, as opposed to changing out a bulb only when one burns out.

    Of course we all disagreed.

    Then he made us do the math.

    I don't remember the exact details, but let's say, to get the Ladder and replacement bulbs, and have one person change the bulb, and one person spot the person, then put the equipment back, might be an hour of labor total. (two people, half hour each, to get the ladder, carry it to the location, set it up, remove the light cover, change the bulb, replace the cover, break down the ladder, and transport the ladder back to it't storage location in maintainance, usually in the basement).

    If there are 100 bulbs in the place, that would end up costing about 100 hours of labor.

    To change the 100 bulbs at one time, might only cost 8 hours total of labor.

    92 labor hours saved!

    NOW, what I didn't realise until many years later, is that if those laborers were a VARIABLE expense, the hotel would save money, but if they were a FIXED expense (like they work 40 hours a week, every week), the labor is a FIXED expense, and there would be no REAL savings to the hotel.

    So the question is, is the city SAVING money by only replacing lights when they go out, and the people that change the bulbs are getting paid regardless of how many bulbs they change, or is it COSTING them money by having contract laborers change one bulb, when for like 5% more, the contract laborors could change all the bulbs at one time?

  20. #20
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    Default Re: LED traffic signals

    Budd...I hope you're speaking of the "house lights" because, at anywhere from $5 to $50+ per bulb "Stage lights" (As found in an auditorium" are quite expensive to replace, especially if not burned out yet, add to that the fact that most modern lighting strands (Depending on stage setup) can be lowered...

  21. #21
    *Flashaholic* James S's Avatar
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    Default Re: LED traffic signals

    I my auditorium we had a drop ceiling and could change the house lights from above. So it was easy, even the freshmen could be trusted to do it. (although you did have to be careful walking on that part of the ceiling as it wasn't reinforced)

    However, we did have a pipe hung down from a couple of house light fixtures to hold more stage lights. there was no good way to get to those. It involved putting a couple of folding tables over the seats and clamping the together. Then strapping the A-Frame ladder to that and extending the extension all the way up. It was still too short so you had to climb up, put one leg on either side of the top rung and then reach all the way up to the lights.

    I can't imagine why I was the only one who was willing to work on those. Thinking back now I can't imagine why I agreed to that job...

    What does this have to do with LED's or traffic lights? Nothing I suppose [img]images/icons/wink.gif[/img] If they had been LED lights they wouldn't have needed changing and they would have been a lot lighter to lift up there...

  22. #22
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    Default Re: LED traffic signals

    It costs $55 to wash a Police Car

    Has to be done by a Union Person
    Officers are not allowed to take their cars through the local car washes

  23. #23
    Flashaholic* sunspot's Avatar
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    Default Re: LED traffic signals

    Free cop car wash in my town. Done by trustee's. The cop tips them a buck. I like the idea.

    Psst, I'm a Union Man.

  24. #24
    *Flashaholic* Darell's Avatar
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    Default Re: LED traffic signals

    Can't speak for all traffic lights - but I know a bit about what's going on in my neck of the woods. All three colors have been swapped out in every light that I've seen here in town. The red absolutely uses red LEDs (almost twice as many as in the green light) and the green light uses cyan leds. I don't know what's used in the yellow lights beyond the fact that they're LEDs as well. The only lens being used is a clear protective lense with a grating/magnifying pattern in it.

    The cyan of the "green" light is the same 5mm Nichia part that I have in front of me right now. I also have Nichia green, and there is simply no question that the traffic lights use cyan here in Davis.

  25. #25
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    Default Re: LED traffic signals

    I am in the Portland/Beaverton area and must be using different adapters where you are

    I have seen the green adapter out of a stoplight
    and its about 95% NiChia Green and 5% Blue; haven't seen a Yellow one yet

  26. #26
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    Default Re: LED traffic signals

    One potential advantage of LED traffic signals that hasn't been tapped yet is the fact that with the reduced power, it is feasible to have them operate on battery back-up in case of power failures. - Lee

  27. #27
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    Default Re: LED traffic signals

    About 1.5 years ago Salt Lake, not necessarily clear out here in Magna, but Salt Lake went ot red LED. I have noticed green starting to compliment the red. Green is definatly creen, not cyan. Yellow is still incandessent.

  28. #28
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    Default Re: LED traffic signals

    Originally posted by beemerphile:
    ... it is feasible to have them operate on battery back-up in case of power failures...
    <font size="2" face="Verdana, Arial">It's already been done.

    There are 2 failure modes. Depending upon the needs, either a flashing red, or fully operational. The decision in some Orange County cities was based upon economics and traffic flow. The prices were $3,000 to $5,000 per intersection.

    I have examined only 2 signals up close, the reds had protective covers, but no filters.

    Amazing what government will do over a fake little electricity shortage.

  29. #29
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    Default Re: LED traffic signals

    Here in NH and Mass, they use the 8" LED traffic signals, I haven't yet seen any 12" dia ones in use.

    A couple years back I got some red LED 12" dia traffic lights on E-bay, one has 504 red HP LEDs, 9 parallel strings of 56 in series, another has over 700 red LEDs also in a series - parallel configuration. I couldn't get an exact count on this one as the red plastic lens is glued to the board. The back of both units is a rubber cover which can be removed, exposing the PC board which has a capacitor-input and then a voltage doubling circuit, which is then current limited to feed the LEDs, this gives the light assembly a wide range of operating voltage, from 85 to 130 VAC @ 60 Hz. The one with over 700 LEDs is incredibly bright, when used indoors, even at a distance of over 30 feet it is painful to look directly into it. [img]images/icons/shocked.gif[/img]

    I also have a green "arrow" LED 12" dia signal, that has 288 of the older generation "lime" green
    LEDs and a similar AC input circuit. Its LEDs are in 4 paralell strings of 72 in series. Not
    nearly as bright as the new ones with the Nichia
    or "true" green LEDs. [img]graemlins/icon15.gif[/img]

    /ed brown in NH [img]images/icons/cool.gif[/img] [img]graemlins/icon14.gif[/img] [img]graemlins/icon14.gif[/img]

  30. #30
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    Default Re: LED traffic signals

    Supposedly one other advantage that LED traffic lights has over incandescents, is that the LED unit can survive getting hit by a bullet or other projectile, it might take out one string of the LEDs, but the rest kep on working, so the traffic signal isn't rendered dead.

    I've seen a few of the 8" ones around here with a dead section, they were probably caused by an LED failure rather than a bullet, as the lens wasn't damaged. I just hope to be around sometime when the utility crew is changing one of these out, and offer them a six pack of adult beverages in exchange. ;-)

    /ed

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