What color are the street lights in your town? While an unfortunate few still suffer under one of the awful colors offered by vapor discharge lamps, like the pink or orange of sodium or the greenish-white of mercury, most municipalities have moved to energy-saving LED streetlights, with a bright white light that’s generally superior in every way. Unless, of course, things go wrong and the lights start to mysteriously change colors.
If you’ve noticed this trend in your area, relax; [NanoPalomaki] has an in-depth and surprisingly interesting analysis of why LED streetlights are changing colors. After examining a few streetlights removed from service thanks to changing from white to purple, he discovered a simple explanation. White LEDs aren’t emitting white light directly; rather, the white light comes from phosphors coating the underlying LED, which emits a deep blue light. The defunct units all showed signs of phosphor degradation. In some cases, the phosphors seemed discolored, as if they experienced overheating or chemical changes. In other LEDs the phosphor layer was physically separated from the backing, exposing the underlying LEDs completely. The color of these damaged modules was significantly shifted toward the blue end of the spectrum, which was obviously why they were removed from service.
Now, a discolored LED here and there does not exactly constitute a streetlight emergency, but it’s happening to enough cities that people are starting to take notice. The obvious solution would be for municipalities to replace the dodgy units Even in the unlikely event that a city would get some compensation from the manufacturer, this seems like an expensive proposition. Luckily, [NanoPalomaki] tested a solution: he mixed a wideband phosphor into a UV-curable resin and painted it onto the lens of each defective LED in the fixture. Two coats seemed to do the trick.
We have to admit that we have a hard time visualizing a city employee painstakingly painting LEDs when swapping out a fixture would take an electrician a few minutes, but at least it’s an option. And, it’s something for hobbyists and homeowners faced with the problem of wonky white LEDs to keep in mind too.
In my city the manufacturer was replacing some under warranty; however the problem was noticed after a significant number of units were installed and now there’s no money to pay for the time and effort to install.
By the way, a few minutes of time by an electrician on a street light is actually closer to 45 minutes + full labour costs. And there’s hundreds – thousands of lights to be replaced.
If it turns out somebody stole a secret recipe for the phosphor I’m going to laugh… (very much like the capacitor issue from years ago).
My former role required traveling to lots of different cities/state in the US. I cannot overstate how many of these blue/purple streetlights I saw all over the place.
The assuming these are a handful of lightbulb manufacturers, they will go bankrupt before covering the replacement costs for all these failures.
It seems like Acuity has replaced many of the failing lights under warrenty but does not pay for the replacement cost. Several cities have settled with Acuity, others have not. The surprising thing, is these are not just an oddity, but they are dangerous especially around high traffic pedestrian areas. To get more specific, it looks like it was the American Electric Lighting (Acuity) Autobahn ATB2 that were made with a new type of white LED made from Seoul Semiconductor that was prone to this type of failure (WICOP-22P).
The hideous flickering blue city lights have to stop. It is a crime against beauty
It is. Blue light inhibits sleep, increases anxiety, and kills natural night vision for a while after being exposed.
I’m convinced that a lot of police interaction problems stem from flashing blue lights.
That’s why streetlights were traditionally amber. Which I enjoyed the most. Amber lights were more closely made to mimick flame which will not limit your night vision. I personally hate the incredibly bright and blinding new streetlights. They seem like some kind of joke like they want to purposefully annoy people. It’s what happens when people make arbitrary contrarian rules. Change everything! It’s the new fad.
Amber streetlights, i.e. hi or lo pressure sodium vapor lights, didn’t show up until the late 80s/early 90s. Prior to that, streetlights were all mercury vapor, with their characteristic intense blue-white color.
Hunh? Where so late? I recall seeing them pretty commonly around 1979-80 — made obvious by the dramatic difference from the mercury lamps used in gas stations.
Imagine this comment contains eye-opening facts and important take-aways, that took 15 minutes of my time to gather, but instead I’ll give you the error message I got: “nonce verification failed”
Not to mention chromatic aberration. If you wear glasses, broad spectrum light makes things blurry. Those old sodium vapor lamps made everything orange and black, but things looked SHARP.
Another note: the buses in my town use yellow LEDs for destination signage. There was one bus that had white LEDs, and people hated it because it was blurrier at distance.
Doesn’t seem to be as common, but I’m seeing purple tinged car headlights more frequently now too.
Some people do that on purpose. Osram has a line of “Cool Blue” headlights that have a blue filter painted over halogen bulbs.
Yes. Before the rise of LED headlights, the best headlights were HID, which appears slightly bluish compared to halogen and regular incandescent headlights. They were first available only on luxury cars and flagship models. So there came a demand for halogen bulbs that mimic the appearance of HID headlights, for insecure people to gain some imitation status symbol. Some of the blue-tinted bulbs are much too saturated in color, potentially running afoul of some states’ laws (such as California) which prohibit any non-law-enforcement vehicles from having any blue lights on them. But that’s rarely a problem because despite these laws being intended to prevent people impersonating law enforcement personnel, they’re severely under-enforced and it’s not that rare to see vehicles whose owners flout the laws without penalty.
HID lights at the end of their lifespan tends to get a hint of colour, pink and purple being most common
The materials are cheap enough that any municipal employee could paint with a wide brush or an airbrush, covering the whole surface, in less than a minute. The bigger problem is that quick UV curing epoxy can’t be used in full sun, so a different formulation is necessary.
If the lamps are mostly identical, I imagine it would be easier to swap out the lamps, and do the modifications en masse in a workshop. Or possibly you could apply the phosphors to a specially designed insert that could be quickly installed in the field.
In any case, I’m guessing the labor is the limiting cost. If it involves a cherry picker, you’re probably talking about at least 20 minutes’ work for two people per lamp.
Add to that the cost (time and money) of closing a lane of traffic if the thing hangs over the road…
“unfortunate few”? “awful colors”? Speak for yourself – I much prefer the nice, warm orange hues of the old lamps vs. the piercingly bright LED lights that cast weird shadows due to the arrays usually not being diffused. Plus, they’re awful for night vision for both humans and animals.
I second that.
Most LED streetlights are hideous in color (cheapest), they are ‘blind’ – they look bright, but you can’t see well under them.
And bad placement of lamps (to cover more area) adds more to the light pollution (both up and into the windows).
third. Sodium lights are much more pleasant to me. And they can actually be more efficient too, in terms of lumens per watt. Plus, they ‘spill’ more light onto the sidewalks, which is nice for pedestrians as well as for cars ability to see pedestrians. And the LED lights around here are actually a whole array of small LEDs, which causes them to cast ‘weird’ shadows. Sort of ‘pixelated’ is the best way I can describe the effect. Overall, I greatly prefer the old lights.
Me four. LEDs are bright, but they provide very little lighting (come to South Africa and you’ll find out how useless LED lighting is). Those orange/yellow sodium lamps are absolute gorgeous, and they penetrate darkness like nothing else. They are also soft on the eyes. I think LED lights for street lighting is dangerous…especially at night when it rains…it blinds you, reflects off everything, and hardly provides any light.
There are yellow and orange monochromatic LEDs, which can be used together in one fixture with warm white LEDs to provide sodium-like light color. And LEDs have an advantage that they can be dimmed in the full range and they can work with motion sensors to save electricity and limit light pollution.
5th, sodium vapour light can be filtered out when doing astronomy, the LED light pollution can´t be filtered.
Brad,
Sodium vapor lights are not more efficient than LEDs. Please stop spreading [provably] false information.
I do agree that their color spectrum is preferable over the blue-shifted LEDs that so many municipalities got duped into buying.
The are actually have about same efficiency, give or take. But much more resistant to heat or bad placement of lamps. LEDs do burn out. or start blinking (another “ugh” failure mode).
Isnt the low pressure shit at least as efficient cuz the narrow band is picked up very well by the eyes? Cause the eyes (both cone and rod) dont respond the same 2 erry wavelength, but the sodium line happens 2 be in a good spot (where the eyes have a strong response}? Like all the light is emmitted in a good band as opposed to broad spectrum light (where some wlengths will not be pickd up effectively), so thus in terms of actual visibility it is as efficient as leds?
Absolutely agree. When a local crew were “upgrading” the light outside our house I harvested the light unit and it sits on the top shelf in the corner of my “office”. Way too bright for such a small room, but pleasant enough when warming up, and the view from the street is very nostalgic. There is one sodium street lamp left now in our village – not sure why it has survived. Perhaps becasue it is only on during the day.
As an amateur astronomer, it’s a lot easier to filter out sodium vapor light from light pollution since it’s basically a single wavelength.
Also as a radio enthusiast, sodium vapor lamps produce less EM radiation.
Yeah, low pressure sodium was pretty efficient, very astronomy-friendly (cheap to filter out without affecting much of anything), and pretty good for night vision using your cones. You can’t see colors with it, but you can see, because it’s not just a mess of bluish haze and halos and reflections like you get from an intense greenish-blue LED. I believe some city in France decided to use amber LEDs of the equivalent wavelength just because they liked the aesthetics better – more warm and inviting, or some such.
Exactly! I was looking for someone to address the light pollution angle and why sodium lighting is good for astronomy.
Yeah, and it’s not professional astronomy that I’m even most concerned with, but just that not even fifteen years ago, I could look all around my house and just barely see a glow from the distant cities, which mostly went away with the filter. I could look at the milky way and the dark sky and feel how much more is out there than our world and its problems. Now, there’s a strong blue glow in every direction, satellites and planes crossing over much of the time, and very few who can see things from that perspective anymore.
Amen, seems the trend is global
I remember the sodium lights. It gave off garish orange light that made everything seems monochromatic. Like you’re trapped in a B&W TV. I hated those and avoided going to store that used it if I was going to be there after dark. Fortunately they seems to have gone extinct from public use before 21st century rolled around, the only place I still see them is on old pictures used on web sites and on eBay as NOS bulbs.
USA. I guess the sodium light may still be in use in older places that hasn’t gone through remodel or upgrade.
Colder places, where any better efficiency would have to be replaced with heaters.
Canada is 100% arctic tundra, dontyaknow.
On Big Island in Hawaii, they still use Low-pressure Sodium lights.
This is because of the telescopes on Mauna Kea.
Sodium light has only two narrow spectral lines ( 589.0 nm and 589.6 nm )
These are trivial to filter out.
LEDs or incandescents have too broad a spectral line.
Big Island resident here – most of the sodium lamps have been replaced by LED fixtures. These new fixtures appear to use some sort of phosphor conversion LEDs – the emitted color is a green-tinged yellow which doesn’t seem as monochromatic as a naked LED. I find them not entirely unpleasant.
at night, things should be monochromatic. that’s just how the eye works
(i think about it a lot because my night vision went to shit on the very day i turned 40)
Sodium vapor lamps produce less light pollution and don’t reduce ones natural low light vision as much. They are the better lamp.
One has to assume the ugliness is the point. Everything these people do seems to be centered around creating an uglier world
“These people”?
Which ones are “These people”? 🤔
The reptilians, of course 🤣
Right… wasn’t one of the main reasons the orange-lights were chosen due specifically to the effect other colors have on one’s night-vision? It’s almost like all it took was one generation to completely forget that we even have rods in our eyes specifically for seeing in low-lighting conditions (e.g. under moonlight). Yeah, it looks monochrome… ’cause, as I understand, the rods detect all colors (thus a brighter image despite similar sensitivity; no color-filteration) while the cones each only detect red green or blue.
It’s friggin’ terrifying driving at 65MPH from a white-lit town’s freeway to the unlit outskirts, before your eyes have a chance to adapt to night-vision again. No wonder everyone needs brighter and brighter white headlights! Some don’t even know humans have night-vision!
Those rods operate only at very low light levels. Literally by moonlight, and you lose central vision at that point, making you effectively blind looking straight ahead.
The issue with blue tinted lights is that the eye cannot focus blue and red-green at the same time when the pupil is wide open. Blue lights and blue objects get a halo around them like you were near sighted. This loss of focus is felt as “blind light” – that looks bright but somehow you feel like you’re unable to see. The second reason is that because of Purkinje’s effect, you lose red vision faster than other colors as the light levels fall, so for things to look “right” you need warmer lights. The third reason is that the eye measures light levels by blue light, so it assumes the light is brighter than it is and constricts the pupil, making you see less light.
Slight quibble; the central blind spot is only enough that you need to look slightly off center to see a star; it’s not like the entire acute area is inoperable and you only have peripheral vision. It’s enough that reading a book by moonlight is sometimes possible.
Also there’s a separate effect as far as things looking “right” which is that with black-body radiation, what appears “white” varies with intensity, so that bluer color temperatures need to be brighter to be seen as white. https://en.wikipedia.org/wiki/Kruithof_curve
That being said, the Purkinje thing ties in nicely with the determination of twilight historically by comparing the appearance of a black thread and a red thread. And with why you can use red lights at night to some decent effect – because they have the most extreme ratio of response between your cones and rods.
In the military I was taught that Military Dawn was when you could distinguish between green and red swaths of cloth.
The central blind spot is about the size of a dinner plate at a couple meters. Looking up the street, it can easily obscure cars, pedestrians and traffic signs.
@Dude, I suppose it may be some time until I can test again, but I really did read by moonlight once or twice to show that I could. Smaller print or faded books with less contrast were a bit trickier. A dinner plate at two meters is about a saucer at arm’s length, and I could hold all sorts of things at arm’s length in darker light than typical moonlight and not be mysteriously blind to them. If I had such a thing as unmodified starlight anymore, that was the level at which you could find an object you set down in a bare patch but not in grass or shadow.
Central vision is about 5 degrees. The typical distance you’d hold a book at is 30-50 cm so the central vision spot at that distance is about the size of a large coin or half of a coaster. It’s 20+ centimeters at 2 meters and beyond. However, since you’re so close up, the amount of light reflecting off the page of a book and hitting your eye is also much more than what you’d get if the object was 2 meters or further away, so the blind spot gets smaller as you get closer – it’s not an on/off deal as the sensitivity from the exact center towards the edges isn’t uniform.
The area of your sharpest vision is about 1 degrees wide, which corresponds to around half a centimeter up close. In moonlight, you will be blind to text if you look directly at the letters, but you can still make out the shapes if you look just slightly to the side.
It’s the loss of light at a distance that makes the difference for objects further away, since the amount of light coming in towards your eyes also spreads out and most of it misses your eye. As objects further away appear dimmer, a wider area of your retina becomes blind to it.
@Dude It sounds like you’re double-dipping on the light spreading thing. The moonlight is equally bright everywhere, unlike a flashlight you’re holding that has to go out and come back again. The fact that you intercept less total light from identical objects that are further away is true at all times, including daytime. But it’s because you’re forming an image of the same brightness on a smaller area of your retina, or on a camera’s sensor if you prefer. The smaller area means less total resolution because you can only resolve a certain amount of detail per area, not because they’re actually dimmer (other than if some of the light got scattered away by haze and such). Otherwise, looking at your finger right in front of your eye would blind you while looking at the moon you’d see nothing but blackness despite it being in sunlight, just because it’s so much further away. Obviously it’s not the case.
That all being said, I’m not saying you don’t lose anything; of course you lose the very most acute central part at sufficiently low light levels. That’s why you have to look slightly off center to see many stars. It’s just you really don’t have to look very far off center, and the acuity in the very slightly off center part is plenty good, and so it’s awfully hard to actually lose track of anything significant until and unless it’s so dark that you have a hard time seeing anything at all. Cars, pedestrians, signs… these are all things that should NOT be smaller than your blind spot until quite long distances that only matter if you’re moving quickly, IE driving or biking. And in that case we use artificial lights which, while they prevent night adaptation, ensure everyone moving quickly is emitting light to be seen and the cars and bikes can light up any unlit people or animals in their path. As a pedestrian, in many cases something retroreflective like road signs and high-vis vests is enough to ensure you are easily seen by anyone who’s emitting light, and you’ll see any other pedestrians easily enough before you get anywhere near bumping into each other. Unless you’ve just been blinded by headlights, of course. That’s where absolutely massive things can be invisible, because most of your field of vision is actually blinded and struggling to recover, so anything the least bit shadowed is now suddenly invisible.
Thank you; I was wondering if a nearby town to me (UK) had blue streetlights deliberately or accidentally and now I know!
Ah, sodium street lights, how I miss you! Far superior to the painfully harsh and blindingly bright stark white modern lights.
Street lights have been like this where I live for years. The local uni colors are purple and white, so for a while we thought it was something “fun” the city did. Found out the truth later.
One of our local sports teams features purple in their color scheme. At first, I thought the purple lights had something do with that team. It wouldn’t have surprised me given the professional sports worship that abounds, but it did turn out to be defective LEDs. The labor to replace them probably ate 100 years of energy cost savings.
Most street lights seem to have some kind of cover over the lights, so instead of painting the LEDS themselves why not just install plastic covers with the phosphor in the actual plastic, also much easier to replace when the phosphors in the covers go (if they do), quicker and cheaper too.
Cheapest price by the lowest bidder strikes again….
I have yet to see this problem here in Japan. I don’t know what brand they use for main roads, but for suburban streets they often use Panasonic usually.
I just wish they would choose the warm white model instead of the horrible cool white…
Quality Chinese engineering…what color LEDs do you want? How long should they stay that color?
(Long enough for the check to clear, apparently)
Most likely the issue here is cost, im sure the chinese can make good quality stable LED lights, just the customers dont want to pay for a quality product.
Cool white is the only way they are cheaper to run than sodium. They can be under driven for the same perceived (lower measured) light output due to vagaries of human vision. Technology Connections has a series about them.
The incentives align with suck.
Municipal guv’mint charges us $4 a month for street lighing apart from property taxes. They better be good.
Never seen any module turn to another color but the first installed modules were horribly faulty. Like one in 10 would develop power supply issues (I presume) and started flashing at epileptic attack-inducing rates. Somewhat surreal.
There’s one on the road to the airport here, on a straight, dark stretch (so you see it for a long while). It’s blinking some complex pattern, like morse code. It’s been doing it for many months. I have no idea what would cause it to blink that way, but not fail outright after so long.
Perhaps it’s prime numbers = )
When fluorescent lighting at a former workplace would start flashing, a call to the company telephone operator was made to notify the facilities maintenance crew that “the light outside (bldg. floor, room) had gone Disco!) Response was usually quick.
There is literally nothing wrong with sodium vapor lamps.
But, back in the day (err, night) astronomers complained about their light pollution.
Those are the easiest to filter, as opposed to white LEDs which are impossible.
That being said, some of the older stuff didn’t actually aim downwards. Now the new stuff does but is so bright that the reflections add up to more than the original stuff did.
Big Clive (Youtuber) tried to bring this to local gov’s attention a long time a go. They have continued to use them and now the tax payer is paying the price…
Today’s bit of trivia – sodium vapor lamps are notable for their high efficiency and their spectral purity.
Effectively, their output is one single spectral line.
In the days before bluescreen, the visual effects community took advantage of this and used it in a matting process for film compositing
https://en.wikipedia.org/wiki/Sodium_vapor_process
This process was especially well developed by the VFX department at Disney, which used it extensively into the 70’s. They had an entire stage devoted to a big sodium wraparound cyc.
Because of the extremely tight spectrum, the process was very forgiving of foreground colors and had little spill, even on white or glossy objects, far in excess of what would be possible with bluescreen for a couple of decades.
Previously seen here: https://hackaday.com/2024/04/09/bye-bye-green-screen-hello-monochromatic-screen/
Actually, sodium is two lines, but they are pretty close together.
I watched a documentary about one single-tracked minded japanese man who didn’t quit unti he achieved a practical high power blue LED. Until then, LED lighting was both manufacturable and affordable.
Ah! Here it is:
https://youtu.be/AF8d72mA41M
Previously seen here: https://hackaday.com/2024/02/14/shuji-nakamura-the-man-who-gave-us-the-blue-led-despite-all-odds/
Heh heh I missed that one.
Low pressure sodium vapor lamps are more efficient, longer lasting, and contribute much less to skyglow and light pollution. They are also much friendlier to astronomers and wildlife, and produce less glare. Sadly, people don’t seem to like they way they look under that light.
We had an almost-happened with phosphor-converted amber (PC Amber) LED streetlights to replace them, like https://crossroadsled.com/lighting-products/phosphor-converted-amber-street-lights/ but they never really got traction, at least nowhere I’ve been.
After a few false starts with lousy bright-white LED replacements for even lousier mercury vapor lamps, my city has hit upon some quite nice LEDs. They use three different brightnesses: bright for intersections, moderate for main streets, and a nice dim warm white for low-traffic residential streets. All are full cutoff and produce no light above the horizon. If we must get rid of low pressure sodium, these are a pretty good alternative.
Now, if only we can convince building and parking lot owners that they don’t need to illuminate their premises with noon sunlight-equivalence and we’ll be alright. There ARE actually laws about that, but nobody enforces them.
This is achievable with LED if that were the target.
Super bright lights also screwup some plant’s flowering cycle.
BB gun is solution.
“… Which are generally superior in every way… ”
What?
LED Street lights are inferior in MANY ways. Though some of these ways could be ‘fixed’ by proper design.
They are too bright. Like, way WAY too bright. It doesn’t just cause problems with light pollution. It is a safety issue unless EVERY inch of the road is being fully lit. Human eyes take time to adjust. Lighting up 95% of the roads 5x brighter means those darker unlit areas are MUCH darker in comparison.
I have run into this dozens of times in places where the system was designed for very dim sodium lamps in ‘dangerous’ areas like blind corners, and then unlit in other areas(lit by your headlights). The new LED lamps were simply bolted to the old poles. This left drivers dazzled when they entered the lit areas, and then blind when they left them until their eyes adjusted.
Unless the lamps are exceedingly expensive, the CRI is awful. I’m sensitive to low CRI, and it is distracting to drive under the cheaper LED lights. These phosper conversion lamps tend to be better, but clearly have maintenance issues.
Speaking of maintenance issues, the systems I have seen tend to be intentionally incompatible. I have even seen replacement parts with DRM lock-in. LED lighting has the promise of lower power draw, at only a moderate one-time cost and low maintenance. In reality the systems have heat problems, or suffer from excessive cost cutting, so they still need frequent replacement anyway. Mmy town only got about 3x the lifetime from LED vs sodium from their 2018 install, which cost 10x the $ to replace compared to the old sodium NOT including the cost of installing the whole new system. It was a BIG net loss. And they ended up having to replace the system in 2022 anyway since the older parts were no longer available. The new parts were, of course, not compatible with the ‘old’ system.
There have been multiple studies that either fail to show improvement in drivers ability to differentiate objects under white LED lighting, or show differentiation is worse, despite the light being “brighter”.
I am loathe to make a claim like this without providing adequate references, but this is 2024 and we aren’t allowed to have functioning search engines. I looked for over 10 minutes and couldn’t find a single relevant result. In fact, I actually suspect that at least one result was AI generated ‘on demand’ to provide me something with relevant key words. WTF is wrong with the Internet these days?
Touched on earlier, light pollution. Wow is this ever a problem. I’m going to repeat myself. Bright. So SO bright.
Some wise fool proposed that all open free information networks will invariably fall to S/N ratio issues.
How does the internet not get peter principled?
How to keep the noise ‘quality’ down?
Obviously you can’t trust a search engine, but can you trust DNS?
LED lights are just going through that awkward ‘aircraft landing lights as ricer headlights’ phase…still.
Rome wasn’t burnt in a day.
I drive with my sunvizor down thanks to these infernal led street ligths.
Ok I take the bait. Not too long ago (about 2 years) the gov replaced the +20yr old sodiums with LED. Most of the LEDs are now flickering or dead. Case closed.
Sodium lamps don’t last that long.
The bulbs were on a replacement schedule.
If they had been 20 year old fixtures, they would have been wasting more power cost than the cost of upgraded UPS ballasts. This was true 15+ years ago when I was running sodium lights indoors.
You know, ROI, the kind of BS that even an MBA can do.
I think I know what UPS means, it’s that blocky van with the person with the packages in it isn’t it, but why do they need ballasts, these trucks are heavy enough already aren’t they?
I’m still confused about the meaning of ROI, BS and MBA.
Typo: HPS, but you knew that.
Before LEDs, they had switching ballasts for High Pressure Sodium lamps. 10-20 years.
More efficient, made bulbs last longer. Paid for itself w the second bulb.
Return on Investment.
Bullshit.
Master of Business Administration.
Sumthin like 10 years ago in our county, when a sodium bulb burned out, rather than simply replacing the bulb they started replacing the entire fixture with a new more energy efficient white LED unit.
I’m still waiting for that dang sodium bulb across the street to burn out! The new fixtures are less glaringly bright, color balanced, and shine down instead of in people’s windows.
Skeptical.
They had stock of old bulbs and you’re the lucky person.
Now there are only a few fixtures left to use the bulbs up.
Are wrist rocket type slingshots illegal in your country?
Never forget, some of the LED fixtures include cameras.
Playing middle school summer 4AM street ninja must be more fun than ever.
I started noticing was probably about a year ago but it was mainly isolated incidents driving by people’s houses. At night. I asked a bunch of people what the heck was up with the purple lights and nobody had an answer. It’s really awesome to finally have closure on this thing that was driving me a little crazy!
This same effect is the reason why TV’s are now getting purple blotches in the picture.
It’s due to the backlight’s leds failing in the same way.
Thanks!
That’s so strange! Now I’m wondering if my friends are wrong; they’ve been saying my city has made certain lights lavender because the color reduces violent tendencies. I wonder if they just made that up or something.
40 years ago they were saying pink made people less violet.
Specifically the Baker Miller Pink. The initial response was calming…but after 20 minutes the reverse was true. Infuriating prisoners in police lockups if they were left too long. Can’t remember the study but many pink holding cells went back to white or grey.
I’m glad I wasn’t the only one who had a memory about that!
Thanks!
Doh!
s/violet/violent
!
There was (still is, in some places) a trend to installing blue lights to deter drug injection in public locations: It makes it harder to see veins. Turns out they just end up doing it under a streetlight or something instead :-/
https://nofilmschool.com/2014/02/why-hollywood-will-never-look-the-same-again-on-film-leds-in-la-ny
I watched Collateral a couple months ago. Wonderful 25 minute documentary on the evolution of street light technology over more than a century, from gas to LED.
https://www.youtube.com/watch?v=y51VUsotZe4
I drove on I84 through HArtford a couple weeks ago and notice a huge section of the highway was lit with blue street lights. It’s been boggling my mind since I saw them, guess now I know why
I absolutelyhate the newer LED light. Gimme my beautiful easy on the eyes orange lights back!
The failing LEDs k8ll my eyes and most of the units I see do not have good diffusers on them. So you have intensely harsh blinding pin points of light coming out of the arrays.
I hate it.
What if they just used a coated lens on the unit, then when it degrades they just replace the lens?
Would adding a yellow tinted lense (fog light lens) work too or only works if coated?
So many questions that makes me want to buy one to test.
About 3 years ago, St. Johns County FL installed over 4000 new LED streetlights as part of some big road projects. Within just weeks most of them started turning purple. A big stink was raised, and the mfr was supposed to pay to replace them all. – – Still hasn’t happened.
Personally, I like them. I find it to be a rather pleasant shade of lavender. I even made some inquiries as to obtaining a few of the old ones (with no success). Way better than the harsh orange sodium street light in front of my own house.
Do these lights have lenses or even just plain glass windows? Or are the LEDs open to the air.
I’m wondering if the magic coating could be applied to the glass if there is any. For repairs it sounds a lot easier than painting individual LEDs. If they did that at the manufacturer.. I wonder if it might last longer.
the issue is cost, the amount of phosphorescent material used would probably jump up orders of magnitudes.
Oh thankfully I’m not alone (judging from the comments) loving the atmospheric amber light of sodium city lights. I loved to stare at the snow flakes dancing in the wind under their light. Nowadays both snow and sodium lights are rarer in my city.
I work for a municipality in VA. Our transportation div was informed by the area power company in 2017 – 2018 that they were informed by their suppliers and manufacturers that sodium vapor and mercury vapor were no longer to be manufactured due to cost, environmental issues, and availability of raw materials. Metal halide fixtures went the same way 8 to 10 years prior.
After much debate, with the power co, inspection of other cities lighting, and simulating the new lighting values in AGI 32 (ind standard at the time) then Visual lighting 2020, (current) we had disagreement over what the power co was calling an equivalent for say a 5 or 8000 lumen HPS in their offerings for Led upgrade. Looking at ies files available from Cree and American Electric Light, available on their websites as well as the power company’s outdoor lighting sites, these factory test files are testing of manufactured fixtures under ideal lab conditions.
So as a lighting designer you have to test or simulate with what is currently out on a specific stretch of roadway and select the current fixture types, lumen value in place, and try as one might try to figure out where a particular lamp was in its effective lifespan. Then like what we did, was to go into the street with a light meter, ( keep in mind that the older light meters were made for Mercury Vapor (MV) and High Pressure Sodium (HPS) not LED, and test what the actual lumen value was on the ground directly below and around the light cone out to 0.0 lumen then document and go back to see if the actual matches what was simulated. Usually it was very close to actual.
With LED offerings by the power company much internal debate was done as to what they thought an HPS to LED equivallant would be. They had thier own standard they come up with as did we. They chose to group LED by cost tier and that lumps MANY fixtures by cost to operate… sure power generation company I get it…They don’t sort by lumen but by tier. So as a city we had to come up with an expected city fixture standard for the Power Co to use in our city.
With LED, manufacturers give many options for not just the lumen output but the way the fixture points out the light as in the distribution. There are 5 federally suggested distribution types and lumen types ranging from 3,300 to 30,000 lumen
across different fictures.
I haven’t started to explain color temp. Our offerings started at 2700 kelvin and went to 6,000 kelvin. 1,000 is about candle flame color whereas 6,000 is considered daylight.
As a city there was discution about our other issue at the time, the federal lighting standards for roadways, interstates, highways, residential, high and low pedestrian conflict and parking areas within the city right of way whuich is ours to pay the power company to maintain. We like many cities had areas where lighting was below the standard so the upgrade was a chance to correct this.
Look up IES. For a signalized multilane roadway our large roads fell in the 1.2 to 1.6 lumen. Pole spacing over 150 feet messes up uniformity by creating dark spots. I’ve seen some pole spacing at 60 feet so to get the lumen/Lux/Footcandle requirenemt for any area can be fun when it was low lit to begin with. Then go from orange light to white light even if it was the same lumen which i have not seen happen in any application, its going to not only look brighter but the distribution if going to have effects as well.
We have had many people say they like the new lights, others not so much, to the point of being irrational about how much light is intruding their property while having brighter sources coming off thier property than we are generating from a downward pointing streetlight pole at 25 foot.
My point here being is that the choice of lighting and correcting old designs and low or no light situations is not taken lightly and the needs of the many apply here. As a city we have tried to acomedate some requests for lighting shields in some residential areas.
The shields are made from the manufactureer of the LED fixture and are designed to fit specific fixtures they are made for. BUT… there are drawbacks to every design. The sheilds are silver metal and dont wrap around the output of the fixture like you would think. ( I would like to see what they used to put on fixtures around airport LZ’s that would be s metal cone to control light glare and not confuse landing pilots. The current shields are in my opinion not well designed. They block light form going, (or not and) from just the back or the left or right side of the fixture.
Now on to the part of why this applies to this article. Many of the decisions a city makes have to be weighed thru the possibility of doing harm vs good for our community. So the power company is responcible for the safe delivery of electricity and functioning lighting. They have thier lawyers as do we. They order fixtures from sources that can be depended on and can supply within a resonable amount of time. (defineing resonable can be challenging)
Since 2018 we have seen manufacturers warranty go from 5 to 7 to 10 years. That’s how confident the manufacturers are getting about the engineering of thier power supply systems and heat dissipation. Phosphor going bad, yes it happens even to Cree. When the power company gets reports of blue and purple fixtures they want to trade those fixtures for good ones while the warranties are valid. This is the municipal argument for not owning all the lights in the city, we looked into this also. The power company stated that they would remove or abandon all underground cabling, remove poles and fixtures because they were their assets. Suddenly upgrading each fixture at $149 each x 20,000 fixtures seemed reasonable.
We have had some residents who thought it would be ok to block a 15′ acorn fixture with duct tape and cardboard so thier Christmas or Halloween display can be seen the way they want. Other cities have had citizens try to modify or sabotage fixtures with mixed results. We were sent video of why you don’t paint a metal shield on an led fixture. Constant light from a source that gets a percentage deflected back into it can store heat. After while under all the wrong conditions, addons to a fixture gets to critical overheat the modification and fixture and can catch fire, then the pole and whatever trees are nearby the rest is a news story.
These fixtures are carefully designed to work the way they do and not made to be modded by the end user. The power company won’t because of previously stated liability and its not our property to modify. In summery, paining anything over a commercial light emitting source comes with heat trap risk and unknown long tern results for whatever random chemistry used or the paint, epoxy, gel, or whatever on the fixture.
Hopefully after reading this people can start to understand some of the ins and outs of this issue. I personally see no problem with innovating and experimenting with tech you have ownership to do with and are able to handle any consequences of this kind of testing. But I don’t expect any large entity to take on a risk of this type.
I love the purple lights! I want one over
my yard!
In South Cambridgeshire our Council took up a very inadvised Private Finance Initiative contract with Balfour Beatty to supply and maintain streetlights, some of which are LED now, so I’m waiting for the purple patches to appear.
It was all kicked off because the EU imposed a lighting standard on us that we didn’t need, having lived happily with sodium lighting for decades, and it caused no accidents to speak of.
Now we have massive light pollution and failing lights that won’t get maintained.
Such is progress.
“bright white light that’s generally superior in every way.”
Eesh. Tell me you’re you are a shut in without saying you’re a shut in..
Amber is vastly superior. Save the white for the workshop
Painting phosphor on like that eliminates the lens. Now the LED is emitting all of its light in all directions. There is exponentially less light hitting the road and massively more light shining in driver’s eyes.
Acorn? Oh those historic globular inefficient radiators into space. Why in some 40 years there has not been a total ban on such luminaries? Historic area, then use historically dim equivalents. DOT standards though, it’s the twenty first century! Really though there is a global war going on things have to change. Restrict, regulate, remove. It’s easy to have a robot at night certify or tag a light weather on your porch, street, or car.
Some LED lights our city put up in parks have lasted less than a year, at least they just went out without a light show. Rent-a-lights from Duke have been put up on squishy mart corner lots that need side shields because they blind traffic in two directions from a block away. Standards need to shape everyone’s lights outdoors. Camerae have been sensitive to low light levels for some time so the “brighter for the camera” doesn’t hold anymore.
Sodium light, the color of hell. Depth perception and seeing wetness on the surface is better in a broad spectrum not narrow. Low pressure sodium is a WW2 invention with the worst color effects for workers. Blue skylights let in that light in the day and at night the place could be flooded with sodium light and it wouldn’t be visible from the air. Red or blue only, day or night.
As one that has driven under sodium lamps for probably half a million miles and under led lights for something around 80 000 miles, i can say beyond any doubt that the sodium lights are far less harsh on the eyes than the new LED lights. Fog and snowstorms are an effing nightmare in white light, while the sodium light cuts through that crap much better.
Where I live, locals actually thought the purple streetlights were to celebrate the college football team and petitioned to keep them. Yup. That happened.