US Streetlights Are Turning Purple(scientificamerican.com)
scientificamerican.com
US Streetlights Are Turning Purple
https://www.scientificamerican.com/article/streetlights-are-mysteriously-turning-purple-heres-why/
121 comments
> people driving at night may notice a moving object in their peripheral vision more quickly under bluish-white light than under yellowish-white light, [...] Gaining improved peripheral vision under blue-tinged light comes with a trade-off, however: once the moving object comes into focus, it becomes harder to see.
If we were switching away from LED to sodium vapor lamps instead of the other way around, they would have written the exact same article but in reverse, still claiming the change makes us less safe.
If we were switching away from LED to sodium vapor lamps instead of the other way around, they would have written the exact same article but in reverse, still claiming the change makes us less safe.
>If we were switching away from LED to sodium vapor lamps instead of the other way around, they would have written the exact same article but in reverse, still claiming the change makes us less safe.
According to letters to the editor in old newspapers, when major US cities switched TO sodium vapor lamps people complained incessantly.
Looking for references to "lights street yellow" in newspaper archives I also found:
* people complaining about the introduction of yellow traffic lights and how confusing and dangerous they were
* companies complaining about new FAA rules standardizing aircraft lighting
* people complaining about the introduction of street lights in general
People really only dislike two things: the way things are, and change.
According to letters to the editor in old newspapers, when major US cities switched TO sodium vapor lamps people complained incessantly.
Looking for references to "lights street yellow" in newspaper archives I also found:
* people complaining about the introduction of yellow traffic lights and how confusing and dangerous they were
* companies complaining about new FAA rules standardizing aircraft lighting
* people complaining about the introduction of street lights in general
People really only dislike two things: the way things are, and change.
No, sodium vapor lights offer great performance in terms of contrast and visibility. Especially in bad weather conditions.
Yes but that's the point: sodium vapour offers worse peripheral vision, so it could make some situations riskier.
no way, once something is into your periferal vision while in a moving car it's too late, and fact does not matter....unless it's moving realy realy fast, and then it's still too late
so the real equation will involve all sorts of other inputs, like the coulor temp, and amount of direct vs reflected light, background light conditions, weather, and indivual perception of any given driver.
*green light is the worst, as our eyes have the greatest sensitivity to it, and out night vision adaptation is to the black and white(muted coulor)
light that is natural.
current regulations are ancient, but there is no reason that a non opiniated solution cant be figured out and implimented
> once something is into your periferal vision while in a moving car it's too late, and fact does not matter.
When you're looking up in your rear view mirror, your view of the road ahead is from your peripheral vision. It most definitely does matter.
When you're looking up in your rear view mirror, your view of the road ahead is from your peripheral vision. It most definitely does matter.
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I feel like nobody here ever drove in San Jose at night prior to 2020-ish.
Because high-pressure sodium I like, LPS as in San Jose is like viewing a monochrome monitor.
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
Thanks for sharing this! I don't know much about light and didn't realize such a thing would possible. This seems like a great technique for cities like mine that want to limit light pollution.
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A friend and I found a contractor to give us a couple of these lights in the Phoenix area. We traced the LEDs back to a Seoul Semiconductor Phosphor on-chip design. We still have a suspicion that LM80 testing didn’t catch this and it was due to a thermal cycling failure. https://m.youtube.com/watch?v=4Mll-YDDAF4
As someone who walks a lot (including, for many years, back late at night from work or school), I really wish they'd made the LED streetlights approximate the original warm color temperature from the start.
Instead of going bright white, high-color-rendition, wake-up-and-kiss-your-sleep-schedule-goodbye, which is what they went with instead.
When the LED streetlights were first installed, they were horrible, and we were promised they would be adjusted, but they never were sufficiently.
Maybe caring about the look of neighborhoods, and the sleep of people who walk or have unfortunate bedroom window positions, would've had a side effect of avoiding the problem in the article?
Instead of going bright white, high-color-rendition, wake-up-and-kiss-your-sleep-schedule-goodbye, which is what they went with instead.
When the LED streetlights were first installed, they were horrible, and we were promised they would be adjusted, but they never were sufficiently.
Maybe caring about the look of neighborhoods, and the sleep of people who walk or have unfortunate bedroom window positions, would've had a side effect of avoiding the problem in the article?
There are 1800K white LEDs as well as phosphor-converted amber made to approximate the look of the classic amber low-pressure sodium.
1800K white can render colors surprisingly well depending on the phosphor mix. I recently put one with claimed (and measured) CRI over 90 into a flashlight and was surprised to see that it actually can render blues reasonably well.
I'm inclined to think those are better choices for street lights than anything daylight-ish, but I also think we should use far fewer street lights. Their presence often reduces the contrast car headlights provide, making it harder to spot hazards while driving.
1800K white can render colors surprisingly well depending on the phosphor mix. I recently put one with claimed (and measured) CRI over 90 into a flashlight and was surprised to see that it actually can render blues reasonably well.
I'm inclined to think those are better choices for street lights than anything daylight-ish, but I also think we should use far fewer street lights. Their presence often reduces the contrast car headlights provide, making it harder to spot hazards while driving.
Each CRI is referenced to an ideal black body radiator at the same temp below 5000k. And there are 7 (or 14) sample points.
I’m not disagreeing with you, I agree that a high cri 1800k would be a nice night light. I just recently deep dived into this last week when my kitchen lights all died last week
I’m not disagreeing with you, I agree that a high cri 1800k would be a nice night light. I just recently deep dived into this last week when my kitchen lights all died last week
High CRI is great for the driver while driving. But it ruins his sleep when he gets home, it ruins the circadian cycle of the people living nearby, and it disrupts wildlife.
We don't really need to see shorter wavelength colours like blues to avoid hazards. Night driving is not photography.
We don't really need to see shorter wavelength colours like blues to avoid hazards. Night driving is not photography.
I think the answer here is to put the high CRI, neutral white lights on the car. Street lights should be warm or amber and don't necessarily need CRI. (Low-pressure sodium has negative CRI).
We could make a lot of improvements by rethinking our approach to street lights. When I've looked for studies on driving safety in the past, it did not appear that street lights improved safety in most places. Where they did help is crosswalks and low-visibility hazards.
At a controlled intersection, it would be easy to have lighting that's activated by a pedestrian pressing a button. Once drivers got used to that, the light being on would serve as a strong indication a pedestrian is definitely present at the intersection, even if they're not currently visible to the driver. For fixed hazards, small marker lights might be just as effective as overhead flood lights; passive reflectors might even have an equal effect, though I haven't read any studies on that.
We could make a lot of improvements by rethinking our approach to street lights. When I've looked for studies on driving safety in the past, it did not appear that street lights improved safety in most places. Where they did help is crosswalks and low-visibility hazards.
At a controlled intersection, it would be easy to have lighting that's activated by a pedestrian pressing a button. Once drivers got used to that, the light being on would serve as a strong indication a pedestrian is definitely present at the intersection, even if they're not currently visible to the driver. For fixed hazards, small marker lights might be just as effective as overhead flood lights; passive reflectors might even have an equal effect, though I haven't read any studies on that.
The main issue that I have with LED lights, is that they are very coherent, so the brights are brighter, but the darks are darker.
This can easily be seen by looking at the shadows under an LED streetlamp, compared to a metal halide one. The LED shadows are very sharp.
This can easily be seen by looking at the shadows under an LED streetlamp, compared to a metal halide one. The LED shadows are very sharp.
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.
> 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.
Cue "I Wear My Sunglasses At Night": https://www.youtube.com/watch?v=X2LTL8KgKv8
I should add that I've only done it when walking, never driving.
It’s a fairly common failure it seems. Here’s it happening in Ireland:
https://www.irishtimes.com/ireland/dublin/2025/02/05/almost-...
I had someone complain to me about how it was a change made by the Green Party for bats: how ridiculous!
No, it’s just a faulty light…
https://www.irishtimes.com/ireland/dublin/2025/02/05/almost-...
I had someone complain to me about how it was a change made by the Green Party for bats: how ridiculous!
No, it’s just a faulty light…
I was told it was to make it hard for people using needles to find their vanes. It turns out it's just the phosphor coating coming apart. The LEDs used to energize that to make the broad spectrum light are usually blueish purple for maximum efficiency.
It does do that and it's used for that.
I first experienced that in a bathroom in England. Door open, regular white light. Lock the door, blue light. I thought I broke something when that happened.
I first experienced that in a bathroom in England. Door open, regular white light. Lock the door, blue light. I thought I broke something when that happened.
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.
Makes you appreciate how tricky it is to balance cost, lifespan, and quality when you’re manufacturing millions of these for cities.
Design choices must include failure modes. IMHO, utterly stupid to only consider happy path.
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.
Here's a video on the topic from 2 weeks ago: https://www.youtube.com/watch?v=Jfr8fmF8oJU
Pretty interesting.
Pretty interesting.
I've never seen a LED streetlight turn people where I live. Sounds like bad light design and the LED is perhaps getting too hot.
Though that said, just go and replace them as they would have had to for sodium vapour lamps they had before? And this time replace them with something that runs them at a lower temperature, especially if the environment during a summer could be hot from external temperature.
Though that said, just go and replace them as they would have had to for sodium vapour lamps they had before? And this time replace them with something that runs them at a lower temperature, especially if the environment during a summer could be hot from external temperature.
All of the purple lights I've seen have been of the same design, and they seem to be in towns that are (at least to some degree) cash-strapped. The manufacturer better be replacing these under warranty.
There aren't any of them in my town, though I've seen one LED streetlight so far that went out. The main streets have lights with a slight yellow tint, and the side streets are neutral white, which I find much more pleasing than the purplish mercury arcs they replaced.
There aren't any of them in my town, though I've seen one LED streetlight so far that went out. The main streets have lights with a slight yellow tint, and the side streets are neutral white, which I find much more pleasing than the purplish mercury arcs they replaced.
> And yet some streetlights have suddenly turned a jarring shade of purple. It is hard to determine the exact cause without dissecting one of the defective lights, but scientists have a hypothesis: bright purple light suggests the phosphor layer around the lights has been “delaminated”—peeled off—exposing the blue LED light underneath, Brgoch says.
What an annoying/bad article. "Here are our guesses of this when we could have actually figured it out". It's not like these are in space and hard to get to, they are on the freaking street. Get a crew out there and figure it out.
Then they go on to do a _bunch_ of handwavy "science" about blue light while not really making any point (IMHO).
> 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.
Ahh yes, for all the people that wear their sunglasses at night, I'll make sure to let Corey Hart know.
This just seems like an incredibly low-effort article with zero definite facts and enough hand waving to sprain your wrist.
What an annoying/bad article. "Here are our guesses of this when we could have actually figured it out". It's not like these are in space and hard to get to, they are on the freaking street. Get a crew out there and figure it out.
Then they go on to do a _bunch_ of handwavy "science" about blue light while not really making any point (IMHO).
> 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.
Ahh yes, for all the people that wear their sunglasses at night, I'll make sure to let Corey Hart know.
This just seems like an incredibly low-effort article with zero definite facts and enough hand waving to sprain your wrist.
FWIW I do wear sunglasses for long highway drives at night.
Without them halogen headlights in my side mirrors give me a migraine after a while.
Without them halogen headlights in my side mirrors give me a migraine after a while.
FYI you can get auto-dimming side mirrors (same mechanism as for rear-view mirrors). I presume it’s a pain to install them after-market, but it can be done and maybe worth it for you if brights bother you enough to wear sunglasses.
When I had some window tinting done on a car, they tinted the side mirrors at no extra charge with excess film.
At first, I didn’t like it, but quickly grew to quite like it. (It’s pretty much only annoying for seeing the curb while parallel parking at night.)
At first, I didn’t like it, but quickly grew to quite like it. (It’s pretty much only annoying for seeing the curb while parallel parking at night.)
I don't think tinting is the same thing as electronic dimming.
It’s not the same mechanism, but they both reduce glare and one is wildly easier than the other to get installed for someone bothered enough to wear sunglasses on night drives.
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 (which haven't really been used at all in many decades) are generally "yellow"-ish compared to modern HID (aka "xenon" or "metal halide") or LED headlights.
Anyway, I'm also bothered by lights when driving at night, and I find the yellower corner of the spectrum to be the least-bothersome of common lighting colors. The glaring ~6000k white of modern HID and LED is much worse, for me, apparently because of the extra blue spectrum.
But if it really is yellow-ish halogen lights in your side mirrors that bother you most*, then I can't tell you that you're wrong.
And if that is then case, I can potentially offer some constructive advice: I've owned a couple of cars (specifically, a 4th gen Firebird and an E36 BMW -- both products of the middle 1990s) that came from the factory with side mirror glass that was tinted a pale blue.
The slightly-blue tint attenuated yellow halogen lights, by design. It's a clever bit of optical filtering.
During the day, in the sun where there's tons of light, they worked mostly-normally: Reflected images had little bit of blue tinge, but whatever.
And at night, the halogen headlights that were nearly-ubiquitous in the 1990s had their reflected intensity turned down automatically. Compared to cars with mirrors that used clear glass, I could still see the lights of the cars behind me just fine. They were simply less-blinding.
It worked great around the times those cars were produced.
If that's really the problem you're experiencing*, then a very pale blue window tint on the mirrors may be exactly what you want for that issue.
* (I asked for specificity because it's important. That Firebird and E36 both became increasingly-annoying for me to drive at night as HID and LED lights became increasingly-common, and towards the end of my time driving them I was seriously considering having clear glass mirrors cut and swapping over to that. Not because the blue tint wasn't effective at filtering out halogen light (it was great at that!), but because it seemed to magnify the problems I experience with HID and LED headlights. The world was changing, and the unchanged spectral filtering became a burden instead of a boon.)
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 (which haven't really been used at all in many decades) are generally "yellow"-ish compared to modern HID (aka "xenon" or "metal halide") or LED headlights.
Anyway, I'm also bothered by lights when driving at night, and I find the yellower corner of the spectrum to be the least-bothersome of common lighting colors. The glaring ~6000k white of modern HID and LED is much worse, for me, apparently because of the extra blue spectrum.
But if it really is yellow-ish halogen lights in your side mirrors that bother you most*, then I can't tell you that you're wrong.
And if that is then case, I can potentially offer some constructive advice: I've owned a couple of cars (specifically, a 4th gen Firebird and an E36 BMW -- both products of the middle 1990s) that came from the factory with side mirror glass that was tinted a pale blue.
The slightly-blue tint attenuated yellow halogen lights, by design. It's a clever bit of optical filtering.
During the day, in the sun where there's tons of light, they worked mostly-normally: Reflected images had little bit of blue tinge, but whatever.
And at night, the halogen headlights that were nearly-ubiquitous in the 1990s had their reflected intensity turned down automatically. Compared to cars with mirrors that used clear glass, I could still see the lights of the cars behind me just fine. They were simply less-blinding.
It worked great around the times those cars were produced.
If that's really the problem you're experiencing*, then a very pale blue window tint on the mirrors may be exactly what you want for that issue.
* (I asked for specificity because it's important. That Firebird and E36 both became increasingly-annoying for me to drive at night as HID and LED lights became increasingly-common, and towards the end of my time driving them I was seriously considering having clear glass mirrors cut and swapping over to that. Not because the blue tint wasn't effective at filtering out halogen light (it was great at that!), but because it seemed to magnify the problems I experience with HID and LED headlights. The world was changing, and the unchanged spectral filtering became a burden instead of a boon.)
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.
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.)
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.)
I’m not sure if someone has dissected them to see what’s wrong and published the results.
Deductive reasoning points to a failure of the phosphor layer in a specific type of led.
Deductive reasoning points to a failure of the phosphor layer in a specific type of led.
Someone did, it's accurate to state this is published work
https://www.youtube.com/watch?v=4Mll-YDDAF4
https://www.youtube.com/watch?v=4Mll-YDDAF4
> Get a crew out there and figure it out.
I mean, to be fair, the city maintenance crews don't generally run tear-down youtube channels with appropriate equipment to take a close look at a failing semiconductor-based light assembly.
But the general point is correct. What could be done is connect with some of those crews' offices, understand what warranties are provided with the municipal purchase of those bulbs, and how much comes out of the infrastructure budget to do an early replacement of these bulbs. Hopefully these bulbs weren't purchased from a RANDOMSYLLABLE amazon china dropshipper who disappeared after 3 months.
But yes, that requires talking to municipal governments, and there's not enough click revenue to support that level of journalism anymore.
Maybe a youtuber who runs a tear-down channel can do that.
I mean, to be fair, the city maintenance crews don't generally run tear-down youtube channels with appropriate equipment to take a close look at a failing semiconductor-based light assembly.
But the general point is correct. What could be done is connect with some of those crews' offices, understand what warranties are provided with the municipal purchase of those bulbs, and how much comes out of the infrastructure budget to do an early replacement of these bulbs. Hopefully these bulbs weren't purchased from a RANDOMSYLLABLE amazon china dropshipper who disappeared after 3 months.
But yes, that requires talking to municipal governments, and there's not enough click revenue to support that level of journalism anymore.
Maybe a youtuber who runs a tear-down channel can do that.
> Hopefully these bulbs weren't purchased from a RANDOMSYLLABLE amazon china dropshipper who disappeared after 3 months.
This is how most LED bulbs in use today are purchased. In theory, LED is absolutely superior when engineered correctly, but it rarely is on a statistical basis when looking at the available products.
It's hard to make an incandescent bulb that is shitty, other than making it not last for a very long time. I'd rather a dead bulb than one that turns my street into a nightclub.
This is how most LED bulbs in use today are purchased. In theory, LED is absolutely superior when engineered correctly, but it rarely is on a statistical basis when looking at the available products.
It's hard to make an incandescent bulb that is shitty, other than making it not last for a very long time. I'd rather a dead bulb than one that turns my street into a nightclub.
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 bigger and many lamp I had couldn't be fitted with LEDs unless I found some smaller ones which are even more expensive.
This is my personal anecdotal experience, but I would be interested if any serious study had looked into this kind of issues.
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 bigger and many lamp I had couldn't be fitted with LEDs unless I found some smaller ones which are even more expensive.
This is my personal anecdotal experience, but I would be interested if any serious study had looked into this kind of issues.
Good leds are extremely durable and should last far longer than anything else, but it seems like there are also a lot of crappy leds on the market.
But it's also important that leds receive the right amount of power. If they receive too much, they'll burn out. We've had this issue with a system where you clip little lights on a rail. It uses GU10 spots which exist in led, so thinking that was compatible, I used leds of course. But our spots kept burning out at an alarming rate. Turns out we need a different transformer for leds. I'm using halogen now, and it works fine.
But it's also important that leds receive the right amount of power. If they receive too much, they'll burn out. We've had this issue with a system where you clip little lights on a rail. It uses GU10 spots which exist in led, so thinking that was compatible, I used leds of course. But our spots kept burning out at an alarming rate. Turns out we need a different transformer for leds. I'm using halogen now, and it works fine.
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. slightly more luminous than the classic 100 W incandescent lamps and with almost white light, only very slightly yellowish, very unlike the yellow lamps with a color temperature under 3000 K, and also very unlike the cheap bluish lamps with a 6500 K color temperature.
My LED lamps are screwed in traditional incandescent lamp fixtures, which hang from the ceiling, but unlike some bad lamp fixtures, mine have below them a diffusive screen, to avoid direct light, but they are completely open above, so they do not impede cooling.
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. slightly more luminous than the classic 100 W incandescent lamps and with almost white light, only very slightly yellowish, very unlike the yellow lamps with a color temperature under 3000 K, and also very unlike the cheap bluish lamps with a 6500 K color temperature.
My LED lamps are screwed in traditional incandescent lamp fixtures, which hang from the ceiling, but unlike some bad lamp fixtures, mine have below them a diffusive screen, to avoid direct light, but they are completely open above, so they do not impede cooling.
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.
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.
Philips are great. I installed the Phillips hue in 2013, they are still going strong. I replaced one out of the 40 or so over the years. It didn’t burn out, it was turning back on by itself…
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.
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.
What, you didn't stock up on incandescents back in 2008?
Phoebus Cartel 2.0
Seems the elements are warrantied for 10000 hours but the drivers are not.
Read somewhere a few years ago this was a manufacturer defect and they were in the hook for replacing them all.
I've (not seriously) considered buying a pellet gun to shoot out the 4 massive neon purple lights at the entrance to my quaint 1970s era neighborhood. They didn't remove the old light poles after installing the new ones about 3 years ago, so it's double lit with sodium vapor and purple now.
Curious is there is a single person on the planet that prefers the white (er, purple) street lights?
I've (not seriously) considered buying a pellet gun to shoot out the 4 massive neon purple lights at the entrance to my quaint 1970s era neighborhood. They didn't remove the old light poles after installing the new ones about 3 years ago, so it's double lit with sodium vapor and purple now.
Curious is there is a single person on the planet that prefers the white (er, purple) street lights?
Single wavelength light is easier to remove or filter out for astrophotography than broad-spectrum light.
But driver safety is probably way more important than my hobby
But driver safety is probably way more important than my hobby
> 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
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?
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
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
They're definitely far far brighter. Here a photo of an old sodium vapor lamp next to a (failing) LED near me: https://photos.app.goo.gl/vwidbJUmG997VLRN7
As far as directional lighting patterns go, that's a matter of the lamp design. Sodium vapor could be housed in a reflector that directs nearly all of it's light downwards.
I'm not against LED technology being used though, just the rampant failing LEDs and the obnoxious brightness & color they produce. Also not fond of the futuristic looking light pole design they seem to always use.
For astrophotography, sodium vapor's color cast is very easy to filter out, whereas the broad spectrum LEDs are not, especially when they don't all emit the same frequencies.
As far as directional lighting patterns go, that's a matter of the lamp design. Sodium vapor could be housed in a reflector that directs nearly all of it's light downwards.
I'm not against LED technology being used though, just the rampant failing LEDs and the obnoxious brightness & color they produce. Also not fond of the futuristic looking light pole design they seem to always use.
For astrophotography, sodium vapor's color cast is very easy to filter out, whereas the broad spectrum LEDs are not, especially when they don't all emit the same frequencies.
I haven't tried them, but they sound awesome.
Better article with lots of pictures and diagrams, links to conference talks, etc:
https://inside.lighting/news/24-05/heres-why-led-streetlight...
https://inside.lighting/news/24-05/heres-why-led-streetlight...
Thank you, this has been happening near me for years now and I've seen countless news articles on it, but this is the first time someone's actually linked what looks like an authoritative source (or at least anything that goes into more detail than "the phosphor is falling off... or something").
My LCD TV did the same thing with a few of the backlight LEDs. Makes a big purplish splotch on the screen. Replaced the backlight strips and took the lens off of one of them and was surprised how small the LED is -- tiny yellow 1.5mm squares.
“ 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.
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.
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.
Strange! I was going to say the exact opposite. I find the near-white light from LEDs very harsh and tiring to my eyes. I often end up rubbing my eyes under them. The sodium orange feels cooler and easier. The strain on my eyes is similar to daylight, but without the alertness it induces. (White LEDs actually feel worse than daylight, for some reason)
There were articles a few years back stating that the blue emissions from these LEDs were rather energetic and damaging to the retina. Conversely, some articles used to claim that red light actually improves the health of the retina. I don't know if those results were corroborated or debunked afterwards.
I know that personal beliefs and biases affect our perceptions. But such diametrically opposite experiences are surprising. I'm curious to know what everyone else experiences and any insights on this.
There were articles a few years back stating that the blue emissions from these LEDs were rather energetic and damaging to the retina. Conversely, some articles used to claim that red light actually improves the health of the retina. I don't know if those results were corroborated or debunked afterwards.
I know that personal beliefs and biases affect our perceptions. But such diametrically opposite experiences are surprising. I'm curious to know what everyone else experiences and any insights on this.
Sodium lights aren’t even orange in the normal sense of the word. They only emit one wavelength.
> Sodium lights aren’t even orange in the normal sense of the word. They only emit one wavelength.
It's hard to think of a more normal sense of the word "orange" than "emitting and/or reflecting predominantly wavelengths between 590 and 620 nm." I guess you could argue that sodium is close enough to that lower edge to be yellow?
It's hard to think of a more normal sense of the word "orange" than "emitting and/or reflecting predominantly wavelengths between 590 and 620 nm." I guess you could argue that sodium is close enough to that lower edge to be yellow?
There are 2 kinds of sodium lamps.
Low-pressure sodium lamps emit a single wavelength and they are the only kind of lamp that does not use LEDs, but which can match or exceed the energy efficiency of LED lamps. However, with low-pressure sodium lamps you cannot perceive any color.
There are also high-pressure sodium lamps. They emit a broad-spectrum light, even if with an excess of orange-yellow light. You can perceive the colors of things with such lamps, even if not very well. However the high-pressure sodium lamps have a much lower energy efficiency than LED lamps.
In Europe I have encountered mostly, or perhaps only, high-pressure LED lamps used for public lighting. I have used at home some low-pressure sodium lamps for certain purposes, but I am not sure if I have ever seen one like that used in a public space, here in Europe.
Low-pressure sodium lamps typically use transparent glass bulbs, like incandescent lamps or any other kind of low-pressure gas-discharge lamps, e.g. neon lamps.
High-pressure sodium lamps use special bulbs made of translucent alumina ceramic, because glass would not survive in those conditions.
Low-pressure sodium lamps emit a single wavelength and they are the only kind of lamp that does not use LEDs, but which can match or exceed the energy efficiency of LED lamps. However, with low-pressure sodium lamps you cannot perceive any color.
There are also high-pressure sodium lamps. They emit a broad-spectrum light, even if with an excess of orange-yellow light. You can perceive the colors of things with such lamps, even if not very well. However the high-pressure sodium lamps have a much lower energy efficiency than LED lamps.
In Europe I have encountered mostly, or perhaps only, high-pressure LED lamps used for public lighting. I have used at home some low-pressure sodium lamps for certain purposes, but I am not sure if I have ever seen one like that used in a public space, here in Europe.
Low-pressure sodium lamps typically use transparent glass bulbs, like incandescent lamps or any other kind of low-pressure gas-discharge lamps, e.g. neon lamps.
High-pressure sodium lamps use special bulbs made of translucent alumina ceramic, because glass would not survive in those conditions.
What is the normal sense of the word? I only know the CIE standard observer to define colour and with this it is clearly in the equivalence class of orange.
I think they mean they don't emit a "natural" orange (like an orange flower) that is really some kind of sum of many wavelengths. I could be wrong though.
A pure orange contains only light with a single wavelength.
A mixture of light with different wavelengths that is perceived as orange cannot be distinguished from a mixture of some pure orange with a certain amount of white light.
So any orange, of a flower or of anything else, has the hue of a single wavelength, but it may be more or less saturated, appearing like light with a single wavelength mixed with some white light.
Low-pressure sodium lamps emit a pure color that belongs to the yellow-orange range, so you could describe it as a yellowish orange.
High-pressure sodium lamps have a desaturated orange color, i.e. light that looks like a mixture of orange and white lights.
The orange of any kind of sodium lamp is much more yellowish than the reddish orange of neon lamps with cathodic light, like those used in neon indicators.
Most sodium lamps contain some neon for starting, so when they are switched on they may emit a reddish orange light for a short time, then change to a yellowish orange light, when the sodium vapor takes over from neon.
A mixture of light with different wavelengths that is perceived as orange cannot be distinguished from a mixture of some pure orange with a certain amount of white light.
So any orange, of a flower or of anything else, has the hue of a single wavelength, but it may be more or less saturated, appearing like light with a single wavelength mixed with some white light.
Low-pressure sodium lamps emit a pure color that belongs to the yellow-orange range, so you could describe it as a yellowish orange.
High-pressure sodium lamps have a desaturated orange color, i.e. light that looks like a mixture of orange and white lights.
The orange of any kind of sodium lamp is much more yellowish than the reddish orange of neon lamps with cathodic light, like those used in neon indicators.
Most sodium lamps contain some neon for starting, so when they are switched on they may emit a reddish orange light for a short time, then change to a yellowish orange light, when the sodium vapor takes over from neon.
> Quality LEDs are quite nice indeed
This is true but irrelevant when cost reduction is the motivating factor for switching to LED lighting, because that motivation will extend to the upfront purchase cost of the lamps and they will buy whatever is cheapest.
This is true but irrelevant when cost reduction is the motivating factor for switching to LED lighting, because that motivation will extend to the upfront purchase cost of the lamps and they will buy whatever is cheapest.
It depends, obviously, but when installed by governments, "cost reduction" almost always takes into account labor to replace faulty lamps, which is especially relevant when there are thousands of the things out there. So governments (for the most part--there are exceptions) avoid the cheapest ones, correctly identifying them as a false economy. The cheap ones are most likely to be found in private parking lots, because parking lot owners are generally only responsible for a handful of lamps and it's a pretty minor part of their business, so they're not going to put much thought into it.
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.
LED headlights are much bigger problem. Way too bright, way too blue.
Both are problems. LEDs are terrible for white light.
LED fixtures with a high CRI (90+), a proper lumen package, and color temperature are indistinguishable from incandescent lights.
Unfortunately, most pole lights are 70CRI, too bright, and the light is too white (4000K+).
Unfortunately, most pole lights are 70CRI, too bright, and the light is too white (4000K+).
The wavelengths are spiky compared to incandescent, and the LEDs flicker if they are not DC-driven.
The flicker is pretty annoying because the transition is an abrupt on-off. Where I am the city had the bright idea to wrap LED ribbons around the poles in the downtown area to make it look more interesting. They connected the ribbons without diffusers directly to the power source of the streetlight. So what has happened now is that as you drive or walk you are looking directly at an unshielded flickering LED.
I still continue to install incandescent bulbs. They look better, and as I live in a cold-weather country the heat they generate is welcomed.
The flicker is pretty annoying because the transition is an abrupt on-off. Where I am the city had the bright idea to wrap LED ribbons around the poles in the downtown area to make it look more interesting. They connected the ribbons without diffusers directly to the power source of the streetlight. So what has happened now is that as you drive or walk you are looking directly at an unshielded flickering LED.
I still continue to install incandescent bulbs. They look better, and as I live in a cold-weather country the heat they generate is welcomed.
It's possible to make an LED with a spectrum that is not very spiky, which a fan of incandescent light will likely enjoy. There is a cost to efficiency, which makes LED fixtures and screw-in bulbs with those traits specialty items. A color rendering index and R9 both in the high 90s is usually enough information to pick out such light sources.
Flicker is also not a given, but a product of using cheap rather than good methods to power LEDs starting from AC mains power.
Flicker is also not a given, but a product of using cheap rather than good methods to power LEDs starting from AC mains power.
There's multiple adjacent parking lots in my city that are full of street lights that emit blue light. I've been wondering for awhile why in the world they would be blue but I think I got my answer. Probably someone trying to cut costs a bit too aggressively. My city and state are known for skimping on anything and everything when it comes to streets and roads.
This is wrong about phosphors in the initial explanation, no? They are actually quite broadband AFAIK.
"LED Filaments" are a more direct example of phosphor-coated blue.
Most everyone has seen these now, in "Edison Bulbs" or elsewhere.
https://en.wikipedia.org/wiki/LED_filament
Most everyone has seen these now, in "Edison Bulbs" or elsewhere.
https://en.wikipedia.org/wiki/LED_filament
To be honest, I quite like this atmosphere. Some roads near my home now feel like something out of a science fiction movie when walked on at night. Of course, traffic safety may not be good, but walking at night adds a sense of fantasy.
A Trader Joe's in Phoenix has had these for so long (years?), the parking lot is bathed in almost completely blue light. They don't seem to care. It really throws off your vision and things look "fuzzy".
Maybe it's just me but the actual color of the light never bothered me. The first time I saw it I figured out it was a form of LED failure. It's so common here that I don't think about it anymore
monochromatic light as emitted by LEDs is quite disorienting.
I grew up in the generation where every manufacturer decided blinding bright blue LEDs were standard features of all consumer electronics. Maybe I am just desensitized to it?
one of the biggest roads in my town has these purple lights at night, and it's very off-putting honestly. Makes it kind of hard to see things properly. I specifically avoid this road at night now because of it.
An apartment building a few blocks over from me has these. It makes the whole area look like a night club. Very weird.
Trade-off-aware software engineers discussing streetlight variant choices is the infinite loop of endless discussion.
We had some of these on my street. Honestly liked them better than the full power ones they got replaced with.
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?
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?
Even the streetlights protest the anti-LGBT narrative in the US :)
Wow!
The comments here!
Are we really such neo-phobe curmudgeons? Sodium hallide street lights preferred over LEDs?
Golly Hacker News, get a grip and join the modern world!
The comments here!
Are we really such neo-phobe curmudgeons? Sodium hallide street lights preferred over LEDs?
Golly Hacker News, get a grip and join the modern world!
We live in a late stage capitalist society. Anything new is almost always engineered to be lower quality in order to cut costs and extract more money from us.
TL;DR - coating is wearing off.
The fix is incredibly simple https://www.youtube.com//watch?v=4Mll-YDDAF4&t=678
Sure, white LEDs are blue LEDs with a phosphorus layer. The Blue LED invention led to the 2014 Nobel Prize for Physics.
I (and my 6-year-old) really enjoyed this video from Veritasium about the invention of the blue LED. https://www.youtube.com/watch?v=AF8d72mA41M
Glad I converted nearly all of the lights in my house to halogen, and stocked up on decades of bulbs, before the ban. Nice warm adjustable light. No strobing LED trash fucking up my eyesight.
Incandescent lights are still widely available if you still want them. Nonetheless, modern high quality LED lights can actually exceed the colour rendering index of incandescent lights, though they tend to be a little more expensive. I don't think it's a big deal to pay $15 for a bulb that will still be there in 15 years.
I'm the opposite; glad to have all LEDs. Cool, dimmable, and energy efficient.
Tldr “ bright purple light suggests the phosphor layer around the lights has been “delaminated”—peeled off—exposing the blue LED light underneath, Brgoch says. Although blue LED lights are, in principle, deep blue in color”
I find it somewhat amusing that they had to find "scientists" to explain this, when the purple tinge is something that LED TV repairmen have been dealing with for around a decade now. However, they're correct that it's because the phosphor layer is getting damaged, probably because they're being driven too hard by the LEDs, which are now being optimised for brightness and recurring revenue instead of longevity and efficiency.
Also, I personally think spirited driving on a purple-lit nearly empty highway at night is a uniquely fun experience with an 80s-retro-futuristic vibe. The streetlights are merely accent lighting at that point; the highbeams are for actual visibility.
Also, I personally think spirited driving on a purple-lit nearly empty highway at night is a uniquely fun experience with an 80s-retro-futuristic vibe. The streetlights are merely accent lighting at that point; the highbeams are for actual visibility.
Acuity has acknowledged a phosphor defect in their lights and had launched a major warranty repair campaign, but I'm not sure how well that's gone given that new failures are still occurring. At least a year ago, they were struggling with the scale of the problem: it just takes a long time to schedule replacement of failed fixtures when there are so many of them.