Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

US Streetlights Are Turning Purple

scientificamerican.com

Post reply on HN
Print view View original

111–120 of 122 posts

Re: US Streetlights Are Turning Purple

#111

Post by xenadu02 »

kuon wrote: post #87

It is not directly related to the article, but the decaying LEDs mentionned in the article made me think of it. Since we had to switch to LEDs, I had to change lightbulbs waaay more often. I realize they consume less (even if here they would just help heat the house so the energy is not lost), but hell they are crap. They start blinking, their color is shifting, they die quickly, they are super expensive, they are bi…

The market is flooded with cheap garbage LEDs. They have shoddy bare-minimum electronics and poor heat control. Something on the board tends to die relatively quickly. If you go to Amazon and buy a no-name Chinese brand or your local big box store (who contracted to a no-name Chinese manufacturer) you are rolling the dice.

On the other hand my entire house is 100% LED from a prior owner gut and rebuild in 2015. With the exception of two LEDs the rest of them still work fine after over 10 years of use.

Re: US Streetlights Are Turning Purple

#112

Post by mrguyorama »

guicen wrote: post #38

It’s interesting how many people assume these purple lights are some kind of new design choice. But really, it’s just a side effect of the phosphor layer breaking down in the LEDs. Makes you appreciate how tricky it is to balance cost, lifespan, and quality when you’re manufacturing millions of these for cities.

It also makes you realize just how willing the general public is to think that you are some conspiracy to ruin their lives, rather than being unintended.

Re: US Streetlights Are Turning Purple

#114

Post by kjkjadksj »

BorgHunter wrote: post #8
CalRobert wrote: post #5

“ producing light that is comparable or better in quality.” They don’t support this claim about led’s, and many groups are concerned about harsh cool light interrupting circadian rhythms. They’re also hideous.

It depends strongly on implementation. LEDs can produce white light at any color temperature and CRIs ranging from terrible to great. Quality LEDs are quite nice indeed (when they're not turning purple). Most LED streetlights replaced sodium vapor lights, though, which produce the sickliest, most horrible orange color known to humanity. Just about any LED is an improvement over those.

The benefit of sodium vapor is it emits a narrow band wavelength. So then if you want to engage in astrophotography you can use a narrow band filter and eliminate quite a lot of local light pollution.

Re: US Streetlights Are Turning Purple

#115

Post by hollerith »

neilv wrote: post #64
hollerith wrote: post #62

Earlier quoted context omitted.

I've started wearing blue blockers when going out at night.

Which is why this part of the article was the frustrating icing on top: > One thing that Bullough suggests pedestrians and drivers do to stay safe under purple streetlights—or any lights, for that matter—is to remove sunglasses and blue-light-filtering glasses when walking or driving at night.

I should add that I've only done it when walking, never driving.

Re: US Streetlights Are Turning Purple

#116

Post by kuon »

adrian_b wrote: post #96
kuon wrote: post #87

It is not directly related to the article, but the decaying LEDs mentionned in the article made me think of it. Since we had to switch to LEDs, I had to change lightbulbs waaay more often. I realize they consume less (even if here they would just help heat the house so the energy is not lost), but hell they are crap. They start blinking, their color is shifting, they die quickly, they are super expensive, they are bi…

There are plenty of cheap LED lamps with inadequate cooling or other bad components, which will become defective after a relatively short time. I have switched all the lighting in 2 apartments to LED lamps, more than 10 years ago, and no lamp has gone defective until now. However, they were Philips lamps and not one of their cheapest models, but some model with 1521 lumen @ 13 W and 4000 K color temperature, i.e. sli…

I am buying philips now when I have to replace them, so far, only 1 philips led died. So they are much more durable, but still not living to the promise of "change once and it will last forever".

I also suspect that many LEDs are designed for 220V, but here in switzerland it is 240V norm and in the middle of the day my power meter reads around 245V (I suspect it is because there is a lot of solar panels on the roofs around me), so it is not a negligible voltage difference if the electronic is not designed for it.

Re: US Streetlights Are Turning Purple

#117

Post by worik »

davidmurdoch wrote: post #76
worik wrote: post #71

Earlier quoted context omitted.

> Curious is there is a single person on the planet that prefers the white (er, purple) street lights? Yes One at least, me (I've never seen this failure mode, so I mean the LEDs) I especially like the reduction in light pollution

I don't understand, you prefer the new LED lights but also like reduction in light pollution? The LEDs way brighter, so I'd think you'd prefer older lights. I'd guess about 20% of the lights in and around Orlando are purple now. Maybe the heat and UV makes it worse here?

Modern LEDs direct more of their light down, less up to the sky, so yes, much less light pollution

Also they are better suited to their job so need less light.

Sodium lights are nowhere near as flexible so are worse, mostly, on both counts

Re: US Streetlights Are Turning Purple

#118

Post by adgjlsfhk1 »

pxc wrote: post #74
PedroBatista wrote: post #34

Earlier quoted context omitted.

No, sodium vapor lights offer great performance in terms of contrast and visibility. Especially in bad weather conditions.

Higher contrast isn't strictly better. Street lights where I live are deliberately sparse to limit light pollution, but this means that some of them are sometimes too bright— since the whole road isn't suffused evenly with light, very bright lights are somewhat blinding, especially to light sensitive people.

LEDs are much better for this since you can get tailored light thrown by angle to even out the lighting a lot more

Re: US Streetlights Are Turning Purple

#119

Post by owenversteeg »

I have to say I'm disappointed in the level of discussion on this subject (elsewhere online and here on HN.) It is obvious to anyone who has ever paid attention to an LED that this is a failure of the phosphor adhesion; more specifically, the phosphor (a fine powder which converts the nearly monochromatic blue-purple LED light to the broader white) is held in silicone, in a small dab on the surface of the LED. The fact that this silicone lasted only a few years is the surprising part; sure, the environment inside the streetlights is harsh (large temperature and humidity swings) but a high-quality silicone should be able to handle this for significantly longer.

It would be nice to read some discussion of the core issue - the silicone - to me, it seems like a total failure of the silicone and not just an adhesion issue, as the photos seem to demonstrate small cracks leading to larger cracks and then total failure. Perhaps related to the addition of something new to the phosphor mix, which might change its properties under thermal cycling? Poorly mixed silicone? Unsteady temps as the silicone was applied?

Re: US Streetlights Are Turning Purple

#120

Post by ssl-3 »

neutronicus wrote: post #105
ssl-3 wrote: post #99

Earlier quoted context omitted.

Are you sure you mean "halogen"? * Halogen headlights have been the most common (and relatively cheap!) kind on the road for many decades. They're just like the tungsten filament incandescent space heaters we used to use at home, except they burn at a somewhat higher color temperature. (And the way they work is really really neat, but I digress.) Halogens, while higher-temperature than regular tungsten headlights (wh…

No, I have no clue, I'm just thoughtlessly repeating what I've heard. The things that give me a migraine look almost purple, so I'm guessing it's HID / LED and not halogen.

Yeah. HID/LED are the usual offenders.

I've found that yellow-tinted glasses help a bunch with those types, and I keep some in the car that I do use occasionally.

(There's a grossly misinterpreted study that people sometimes point at when saying that yellow glasses can't help and can only hurt, but the study itself doesn't support that conclusion.)

Post reply on HN