Buses and 18 Wheelers using LED's on backlights?

BuddTX · #1 03-02-2003, 08:18 PM

Anyone know anything about these?

Anytime I am in back of a Metro bus, I notice their brake lights and turn lights, and they appear to be LED's.

Some of them look like normal Nichia lights (the yellow ones) but the red brake lights appear to be bigger, luxeon sized led's.

anyone know anything about these?

Willmore · #2 03-03-2003, 11:03 AM

Most new construction and any modification/repair on semi-trailors and busses is being done with LED based modules these days. They are almost perfect for the application:

1) low power
2) long life
3) near immunity to vibration
4) Perfect color without a lens
5) easy to modulate into high/low light output
6) Don't require a lens (cheaper fixture)

The primary reason is decreased maintenance costs to replace burnt out bulbs, but decreaded chance of fines for not having a proper set of illumination on a vehicle comes into play, as well. There is even a study by a university in MI which indicated that the faster response time (from power to light) of LEDs improves traffic safety by providing the following driver with more response time to the actions of the vehicle they're following. That is an important point as it's a prime selling point for towns/cities who are trying to justify spending for retrofits to LED signals. If you can show the public that you'r doing it for their safety.... [img]/ubbthreads/images/graemlins/smile.gif[/img]

James S · #3 03-03-2003, 11:08 AM

[ QUOTE ]
Willmore said:
There is even a study by a university in MI which indicated that the faster response time (from power to light) of LEDs improves traffic safety by providing the following driver with more response time to the actions of the vehicle they're following. That is an important point as it's a prime selling point for towns/cities who are trying to justify spending for retrofits to LED signals. If you can show the public that you'r doing it for their safety.... [img]/ubbthreads/images/graemlins/smile.gif[/img]

[/ QUOTE ]

But, once the public gets used to it any safety improvements go away completely.

Like with anti-lock breaks. Initially they improved safety, but the last study now showed that there are exactly as many accidents with them as without them. This is because people have learned to depend on them! So they drive just that much more recklessly.

The same will happen to LED lights, people will learn to ignore them and react more slowly because they come on too fast.

Willmore · #4 03-03-2003, 11:19 AM

Well, that's a very simple conclusion based on premise #1:

List of premises:
1) People are stupid
2) Groups of people are often stupider than individuals

Colliary:
Governments are large groups ... [img]/ubbthreads/images/graemlins/smile.gif[/img]

James S · #5 03-03-2003, 11:27 AM

Willmore, your corollary needs more info, let me expand on it a bit if I may [img]/ubbthreads/images/graemlins/wink.gif[/img]

"Governments are large groups with no incentives for being smart and no individual accountability for being stupid..."

Willmore · #6 03-05-2003, 12:25 AM

I was just commenting on the externally observable properties, the details of how it works don't concern me. [img]/ubbthreads/images/graemlins/smile.gif[/img]

PhotonBoy · #7 03-13-2003, 07:47 AM

One minor drawback of LED lights vs standard filament-based lights is that there's little waste heat, meaning that in icy or snowy conditions, the lights will have a greater tendency to become obscured by accumulated ice.

Quickbeam · #8 03-13-2003, 08:27 AM

"A 'person' is smart. 'People' are dumb, panicky, dangerous animals, and you know it." - MIB

One of my favorite movie quotes. [img]/ubbthreads/images/graemlins/smile.gif[/img]

Now back to your regularly scheduled thread...

I've seen this too - 5 red LEDs behind a lens, and about 10 or more yellow ones on a turn signal. I think the red LEDs are "spider" LEDs. They're very bright and probably just have a larger lens in front of each LED to direct the light better. Fewer are needed because of their high output.

supertrucker · #9 03-13-2003, 08:28 PM

I have LED's on my 2003 Freightliner tractor, and they are so cool! "PhotonBoy is exactly right, they do not produce enough heat to keep snow and ice from building up on them, my company is to cheap ( shortsighted actually, since in the long run the use of LED's would be cheaper!) to buy them for our trailers. The LED tail lights on my truck are rivited in, because they vanish "lickity split" when they are just held in with a rubber grommett!!! They are at least $20 each to replace the LED's, verses $3 for sealed beams!

EMPOWERTORCH · #10 03-31-2003, 05:30 AM

Looking at it logically, in the long term, lorry and bus operators are going to save in several ways by using LED back lights.
1. Diesel usage will be lower, not significant but noticeable over a large number of lorry/bus miles.
2. No cops will pull you over. That saves a fine and the re-start of your lorry (A lorry can use a gallon of fuel going from 0 to 55 mph!)
3. Cost of replacement bulbs, again minimal, but if you have a large fleet....
4. Cost of maintainence of said lorries/buses!

highlandsun · #11 04-01-2003, 02:08 PM

I suppose you could solve the icing problem by mounting a fine wire screen over the LEDs, attached to their bases, to act as a heat sink.

One of the things I'm noticing with my Luxeon Star turn signals is that they look like the 4 point sources they are, rather than like a glowing lamp. Obviously with an incandescent bulb in the lamp, half of the bulb's light is emitted backwards, hits the reflector on the rear of the lamp, and then projects forward, so you see colored light coming from the entire housing. With the Stars there is no rear emission, so the reflectors aren't lit up much themselves, so all you see is the direct illumination. Seems like adding a small dish reflector in front of each Luxeon would give me the total housing illumination effect.

I'm not fond of the point-source effect, and those truck and bus lights look the same way. Of course, the effect is reduced a little because they usually have some kind of diffuser lens, but still, seeing a cluster of point sources vs a uniformly glowing surface is a bit off-putting somehow.