Really bright LED streets lights in town

These monsters popped up about a month ago downtown. Initially I thought they were metal halide, but after driving under them it was obvious they were LED and part of the City's test area.

One thing is for sure - there is no debate on brightness. They easily match the HPS cobra heads in terms of visual brightness, which can be seen in the distance. They are too bright to look at directly and had to use my camera to discern the individual emitters - All 120 of them. I thought we built some bright lamps for reef tanks, but these things look like something from a Spielberg movie set. Surrender people of earth:



Given the ability of these things to turn a street into near daylight, you'd think I'd have nothing to complain about. However, now that I see a fully illuminated stretch of road using state of the art lamps I can see at least some of the pro HPS arguement. Basically, while the intensity of the LEDs is not an issue, they were typical cold-white emitters at least 6000k and the high color temp seemed harsh. I know there's a lot of perceptual differences between the long spectrum of HPS and cool white LEDs, but I didn't think it was this extreme.

IMHO, I'd rather see more red mixed in and a more neutral light at around 4100k and lose a little efficiency. The high color temp just seems like it be a bigger issue than I thought. The local interchange is using 4100k MH, and the effect on visual clarity seems superior.

http://farm5.static.flickr.com/4021/4448783007_2e418033b0_o.jpg

[over-size image replaced by link - DM51]

You're probably right about dropping the CCT a bit, but not too much. The good news is Cree has XP-G neutral whites in R4 coming soon. If we assume they'll be releasing the S2 cool whites in roughly the same time frame, it's not a huge efficiency hit, perhaps only around 10%. Or you can use cool whites with a small percentage of reds to bring up the CRI and drop the CCT ( this works especially well if the cool whites have a green tint which needs to be balanced out ).

I'd have to see it in person to make a judgement one way or the other. Any way you look at it, it's world's better than HPS, although maybe not quite as good as MH ( except in terms of longevity/power consumption ). I could personally get into the high CCT, "the aliens have landed look" but I guess that isn't for everyone. I have to say I'm beyond glad though that HPS will hopefully go into the dust bin of history in the next few years.

How are the tints matched between lights? I won't even ask between emitters. I'm sure it would be impossible to pick up anything there with the retinal overload.

The light intensity distribution seems superior to anything I've seen also. I looks like a nice smooth wall of light hitting the street, with none of the darker spots apparent with the HPS further down the road.

Color looks dead on from unit to unit. I could run a tonal map to bring up some minor differences, but if you can't see it visually.......

Because of the optics there's very little horizontal scatter - unlike most cobra heads. They obviously throw light exactly where intended. I just think something closer to 4100-5000k might work better in the perceptual envelope.

At the opposite end of the spectrum a close suburb is using high-tech, 1000watt HPS in state of the art reflectors, and those things totally suck. I don't mind lower powered HPS if they are close together, but it might just be because I'm accustomed to to them.

Can't wait for college kids to start shimmying up the light poles with a pipe cutter and stealing these for parts Put some cheap 10degree optics on those things and get into trouble.

This is an interesting development. I wonder who makes those, and of course, how much they cost.

Problem is that the lights were probably specified based around RP-8 which somewhat assumed HPS and did not give any thought to spectrum. When you take scotopic response into account, LEDs are perceptually far brighter...even though the LED vendors would much rather make them less bright... hence cheaper.... and sell a ton more of them!

Unfortunately they can not .. and hence we just find them too bright and harsh.

You've just gotten used to the color of HPS, that's all. I remember when they first rolled-out HPS lights in the town I grew up in, I hated them because all I could see was orange. I've gotten used to them now, but I still prefer the old mercury-halide lamps for their ability to provide white light. These are the same color, probably higher CRI, and contain no mercury. What's not to like?

Go stand in a field on a cloudless night when the moon's out; the light is the same color as those lamps.

:huh2:

You've just gotten used to the color of HPS

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Um, no. There are several stretches of road here using 4-5k metal halide, and the over-all balance is far superior.

While bright, these LED fixture gives the illumination of several hundred cheap LED flashlights duct taped together and hanging upside down. Efficient, but not what I expected. If the color temp could be dropped they'll likely get more acceptance.

Not sure of the color temp of the moon, but I doubt it's ~6500k / 65 CRI.

Illum said:

for places that are basically freezing or near freezing year round, this could be a very good investment, but for places that'll hit 80F even at night they'll burn up in a hurry:shakehead

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That is an ignorant statement to make if you do not know the make and the quality of the thermal design. For one, they are only on at night. 80F which is under 30C is not that hot....when you consider some modern LEDs can do 50,000+ hours with die temperatures at 135C ..... which gives a lot of room for the heat sink to work...

Semiman

just an observation, no offense intended:thinking:
I have yet to see a decent thermal design around here that'll last for a full year.

Just started another topic about this but i thought id post here as its similar

there are some new LED street lights in my area (housing estate)

36 leds per unit 4800 lumens

semi / illum - albeit a different fixture - ive seen the construction in person and they are very well made
specs claim leds (junction temp) are kept at around 30 degrees C
they are only run at 350ma and leds are directly fixed to aluminium housing (which is big) and the company will replace like for like free for up to 10years
so good designs are out there

the moon is about 4100K and yes these led lights should be the same - it is in my opinion the only flaw the units in my street are under 6000k so i supose they are daylight but they look a bit too blue but i do think a lot of it is psycological / eyes compensating

blaster: i cant really see how you could expect anything else i would say they look like 36 high quality flashlights (not 36 cheep ones)pointing in a slight arc but these may be a lot better quality than the ones you have seen

jtr1962 said:

The light intensity distribution seems superior to anything I've seen also. I looks like a nice smooth wall of light hitting the street, with none of the darker spots apparent with the HPS further down the road.

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I agree with this 100%. The lights appear truly seamless.

Illum said:

just an observation, no offense intended:thinking:
I have yet to see a decent thermal design around here that'll last for a full year.

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Well, it looks like we'll see how that goes shortly in my neck of the woods.

Here in Las Vegas, I've noticed two 7-Elevens that have what I'm 99% sure is LED lighting for the gas pump area (West Charleston/Buffalo, and Washington/Buffalo locations). Ambient temps in Vegas just after sundown can be as high as 105 F in the summer.

I plan to take a CD over there to check the spectrum, but based on their pure steady-state illumination (as opposed to the 120Hz pulsing of metal-halides) and grid pattern, I'm pretty sure they are LED's.

What has me scratching my head is if they are passively cooled or not. I know from my my reef tanks what it takes to cool 60watts of LED.

The coverage of these things is fine. The lack of color depth in another.

I'm just annoyed at this kind of thing because it's harder to filter out of the telescope!

csa said:

I'm just annoyed at this kind of thing because it's harder to filter out of the telescope!

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HPS isn't any easier to filter as it still has a broad range of wavelengths. LPS is the only type of light source amenable to easy filtering. However, it's totally unsatisfactory for street lighting on both safety and aesthethic grounds ( so is HPS for that matter ). LED in theory should offer astronomers darker skies, despite the broad spectrum, by virtue of putting light only where needed. Conventional discharge street lamps send a large percentage of their output right into the sky.

blasterman said:

The coverage of these things is fine. The lack of color depth in another.

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They may not be high-CRI, but these LEDs are worlds better than HPS in terms of CRI and color temperature. Using LEDs closer to 4500K to 5000K would likely solve any lingering CRI issues.

jtr1962 said:

Using LEDs closer to 4500K to 5000K would likely solve any lingering CRI issues.

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Interesting - a lot of people seem to want about 4100K.

I think it really depends on the actual illumination I think at the pedestrian or drivers' level.

The articles which I found of most help were these:

the Kruithof curve and The Color of White

However I am not too sure if better CCT which does make the lighting more pleasant/acceptable actually improves the CRI.

They may not be high-CRI, but these LEDs are worlds better than HPS in terms of CRI and color temperature.

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Although I'd agree about the CRI - as HPS (sodium) lighting is basically monochromatic -
I am surprised by how well I can actually see definition under the very yellow/amber lighting -
I think it may be to do with our eyes' response and focus at the yellow wavelengths -
I am only tallking about "definition" and not color rendition which is probably close to nothing with HPS.

I know that it is hard to get an accurate representation of actual color temperature when using a camera but, that picture you posted of the street looks wonderful.

I prefer my lights to be a bit on the cool side and that street looks very nice to me!

I am surprised by how well I can actually see definition under the very yellow/amber lighting -

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Same here. While driving under HPS, I tend not to notice the lights or color at all. Just the road and objects, and the light envelope projected by HPS (or even 4100k metal halide) tends to blend evenly into dark areas without causing contrast problems.

When driving under these cool-white LEDs I notice the lights and color immediatley. Also, the actual 'light envelope' from the LED lamps seems more abrupt and stark. Even though HPS down the street aren't as bright visually, they actually seem to cover a wider area. There's no arguement with me that most of this is simply perceptual reasons.

Lets call a spade a spade. The reason cool-white emitters are being used is because they have a very high lumen to wattage ratio - they sure as the hell don't win awards on perception or aethestics. In my opinion I'd just as soon pay the 20% or so spectral/energy penalty and use a more neutral color. If I were to set these up lights up on a street and neutral emitters on the next street and have drivers take a vote, I'm sure the neutrals would win by 90%.

The streetlights on a section of road near campus are LED. It's a block of aluminum with a grid on top (to keep birds out, but not rain) with an array of LEDs underneath, wrapped in thin metal to look nice. They light it fairly well, I'll get pictures next time I'm near there at night.