LED Trafic Lights

[Sakugenken]

It seems like most of the new traffic lights here are LED. Is that also happening in the States?

 

[NewBie]

Yes, the same thing is happening in many areas of the States.

Unfortunately, alot of cities went with the bottom dollar bids from folks using LEDs from HK and similar areas, and that or other parts of designs fail very early, in some cases resulting in an average lifetime of six months to failure.

 

[han]

Yep,, all of the lights here in sugar land have been replaced..I like them,, because if 1 or 2 of the led's are out you can still tell what it sais,, while if the whole light-bulb was out,, you couldnt

 

[Sigman]

Railroads converting as well...

 

[jtr1962]

[ QUOTE ]
NewBie said:
Unfortunately, alot of cities went with the bottom dollar bids from folks using LEDs from HK and similar areas, and that or other parts of designs fail very early, in some cases resulting in an average lifetime of six months to failure.

[/ QUOTE ]
I'd say the problem stems more from the circuit driving the LEDs than from the LEDs themselves. I've been using those "cheap" HK LEDs you speak of and I'm quite satisfied as to their brightness and quality. The only thing cheap about them is the price, which is good because at $1.50 each or more Nichias are quite frankly a ripoff. The key with LEDs (or any electronics) is to have adequate surge and spike protection. Sadly, many of the current LED traffic light designs were made by people used to working with incandescents. As a result, they're lacking in the protection department. Also, a simple resistored setup is not the way to go. You need at least filtering and current limiting.

 

[Lynx_Arc]

They have been putting them in here... and most people cannot tell the difference in the incans and LED traffic lights. The major advantage over incans is replacement cost, I would guess it costs more for someone to replace the incans every once in awhile than to put in an LED version once and hopefullly only replace it once in 5-10 years or so.

 

[greg_in_canada]

[ QUOTE ]
jtr1962 said:
I'd say the problem stems more from the circuit driving the LEDs than from the LEDs themselves. I've been using those "cheap" HK LEDs you speak of and I'm quite satisfied as to their brightness and quality. The only thing cheap about them is the price, which is good because at $1.50 each or more Nichias are quite frankly a ripoff. The key with LEDs (or any electronics) is to have adequate surge and spike protection. Sadly, many of the current LED traffic light designs were made by people used to working with incandescents. As a result, they're lacking in the protection department. Also, a simple resistored setup is not the way to go. You need at least filtering and current limiting.

[/ QUOTE ]

There may also have been not enough testing done for
thermal cycling (causing solder joint failures) and
vibration (notice the road vibrating when a heavy truck
goes past).

Greg

 

[greenLED]

We got'em here too (only green, though), and we've started to notice some LED burned (in rows??). Actually, a couple of lights have been changed back to incan.

 

[han]

I have never seen rows burned out..odd,,just like 1 or 2.

 

[greenLED]

Yup, there were 4 or 5 LEDs in a row, smack down the center of the light. I have no clue how these are wired and why a row would burn out.

 

[EricB]

Once again as was said; probably the circuitry. In Times Sq. also, all those new full color signs; after a few months, you see lines out, lines that don't go out, or stay one color; and the same with whole square panels, and even some individual ones scatered around.
The traffic lights here, however; you rarely ever see any out. I saw a line out in the reds when they were fist installed; but not since. Sometimes you do see one aspect flickering dimly when it should be off. Also, here in NY, they have skipped the yellow. From what I hear, the city didn;t like the amber, and since that color is on the least, itdidn't make sense to change them.

 

[ReynolS]

They are all over the place here in the Phoenix Arizona area!

 

[bobisculous]

Yea, we have about 2 intersections in my area of Houston(northeast)... They suck! Houston didnt spend any money on em therefore they are crap and are going out. They flicker in rows. I know that its Houstons fault(for not spending money on them) and not weather or anything cause right outside of Harris county and into Montgomery county(right where I live), they have some and they have worked great...Montgomery county knows how to time a light as well and waste less gas.

Cameron

 

[Robban]

I live in Sweden and pretty much all lights have been converted to LED for quite a few years. I have yet to see any of them fail.

 

[Ratso]

One thing I like about LED lights is that they are not washed out by the sun as easily. LED's seem to be more visible than incandescants.

 

[Reptilezs]

my town has led traffic lights. we probaly had them for about 1.5 yrs. i feel that they are brighter than the incandescnt lamps. havent seen any burnt ones yet.

 

[Leeoniya]

we have quite a quite a few as well. most semi trucks are going that route too...as every other kind of indicator should. leds are definitely brither, prtoabably cause each one is focused, but the whole point is for them to be that way since they need to be, in essance, directional. thats why there were those new lights for a while that you couldnt tell wtf color was on from the side, polarized or something. it was always strange to me that only the greens were initially converted, rather than all of them. i would think it would be easier to not go cross-system as far as circuitry goes to have both incan and leds in the same stoplight. and yes, the current limiting is critical as well as spike protection, it doesnt cost much to place several TVS chips and capacitors into a circuit that is mass produced, much cheaper than recalling every one that blows out. and as far as brightness, again, i can tell and LED light around here from an incan one from probably a mile away, but definitely at least half a mile. and if you stare into one as you're passing it, or standing at a red, it does hurt the eyes. : )

Leon.

 

[MikeLip]

Our small town has replaced all the traffic light lamps with LED arrays. So far so good. I haven't noticed any of them out. They're easier to see than the old incandescents, too.

 

[nekomane]

I've read about an animated traffic light for pedestrians where a sequence of blinking LEDs make it look as if the figure is walking. Cute /ubbthreads/images/graemlins/wink.gif

 

[NewBie]

[ QUOTE ]
jtr1962 said:
[ QUOTE ]
NewBie said:
Unfortunately, alot of cities went with the bottom dollar bids from folks using LEDs from HK and similar areas, and that or other parts of designs fail very early, in some cases resulting in an average lifetime of six months to failure.

[/ QUOTE ]
I'd say the problem stems more from the circuit driving the LEDs than from the LEDs themselves. I've been using those "cheap" HK LEDs you speak of and I'm quite satisfied as to their brightness and quality. The only thing cheap about them is the price, which is good because at $1.50 each or more Nichias are quite frankly a ripoff. The key with LEDs (or any electronics) is to have adequate surge and spike protection. Sadly, many of the current LED traffic light designs were made by people used to working with incandescents. As a result, they're lacking in the protection department. Also, a simple resistored setup is not the way to go. You need at least filtering and current limiting.

[/ QUOTE ]

Actually, the Nichias get cheaper in volume, at 0.43 ea for whites, and cheaper in other colors. Though if I was doing colors, I'd highly consider Toyoda-Gosei.

Also jtr1962, are your HK LEDs exposed directly to the weather...?


BTW, someone is using some sort of different setup on some around here, my wife pointed out single LED failures to me one day, and we have seen green traffic lights with up to five random dead LEDs. Either they are individually driven, shorting out individually, or there is a bypass diode that turns on when the LED is out...