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US Streetlights Are Turning Purple

scientificamerican.com

101–110 of 122 posts

Re: US Streetlights Are Turning Purple

#101
post #16

Earlier quoted context omitted.

Sodium lights aren’t even orange in the normal sense of the word. They only emit one wavelength.

I thought it was two - the sodium double emission line.

The lines are so close that their hues cannot be distinguished by a human eye.

Re: US Streetlights Are Turning Purple

#102

Earlier quoted context omitted.

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.)

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.

Re: US Streetlights Are Turning Purple

#103
post #56

Earlier quoted context omitted.

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.

> 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.

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.

Re: US Streetlights Are Turning Purple

#104

> 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 ha…

>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.

Re: US Streetlights Are Turning Purple

#105
post #99

Earlier quoted context omitted.

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.

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

No, I have no clue, I'm just thoughtlessly repeating what I've heard.

The things that give me a migraine look almost purple, so I'm guessing it's HID / LED and not halogen.

Re: US Streetlights Are Turning Purple

#106

Earlier quoted context omitted.

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

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.

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.

Re: US Streetlights Are Turning Purple

#108

Earlier quoted context omitted.

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.

Makes the cocaine easier I see too! Social economic apartheid for the win!

It's harder to find a vein with it. It's not for efficiency.

Though linking it to the lock isn't terribly useful, most heavy addicts won't care if anyone opens the door on them.

Re: US Streetlights Are Turning Purple

#109
post #87

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

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

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…

Re: US Streetlights Are Turning Purple

#110
post #87

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

What, you didn't stock up on incandescents back in 2008?
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