Comment by roughly
7 hours ago
I'm reminded of an article a while back talking about how the change from sodium streetlights to LED streetlights had a whole lot of unforeseen effects on animals, people's sleep patterns, driver awareness and visibility, etc. due to color changes. There was a comment on the article from an old civil engineer saying "no, these were not unforeseen, we actually did the research back in the day to figure out what color the street lights should be, that's why they were the color they were."
> that's why they were the color they were
That doesn't seem right to me. Sodium (and mercury) vapor lamps are the color they are due to physics, and were chosen because they're very efficient (and long lasting). Low-pressure sodium is the best and worst of these; essentially monochromatic but fantastic efficiency. Their only advantage, color-wise, is that the light can be filtered out easily (they used to be widely used in San Jose because Lick Observatory could filter out the 589 nm light).
The monochromatic light emitted from sodium lamps is also close to the peak sensitivity of the human eye. Colours are not distinguishable, but contrast is much enhanced compared to “cooler” light sources.
*edit: but it’s the overwhelmingly larger lifespan (20-30k hrs) that led to the wide adoption as streetlights. And I guess, the same is true for the change to led today, because of less power consumption.
It's not close to the peak sensitivity of the human eye (in either bright or dim conditions), but that's okay. The goal should be to not affect people's level of dark adaptation. If you use bluer light (as happens with LEDs), it causes people's eyes to become bright adapted and effective night vision is ruined.
Sodium lamps were deemed dangerous for driving” because they made it difficult for drivers to distinguish shapes, since they were different from day shapes. A kid in bright 1980ies colors (Little Red Hood) would look black under those lights.
LED was presented as a sharp improvement because of the large spectrum of white light.
...And the old Engineer was just saying that that was the area on the spectrum they aimed for, so they found a light that emitted in that wavelength that could be technically implemented and scaled.
Way better work than whoever it is handling this LED nonsense. Why we can't find a diode that we can use to simulate the old spectra would be a fun research project.
We of course can make LEDs of more or less any color. The current white LEDs are high-power blue LEDs that are covered by various phosphors to give a mix of colors for "full spectrum" illumination. Different color temperatures are produced by different mixes of phosphors. This is pretty similar to how the traditional luminescent (mercury vapor-based) lamps worked.
But different phosphors have different efficiency and price. LED lamps were first introduced for interior lighting, where sun-like spectrum is welcome. Such LEDs were produced en masse and relatively cheaply. So street lighting naturally used them, because municipalities usually look for the cheapest viable option.
We likely could produce high-power narrow-spectrum orange LEDs if there was a large market for the economies of scale to kick in. You can buy deep orange LED lamps today (look for color temperature 1800K or 1600K, "amber"), but they are more expensive, because they are niche.
Modern street lighting provides a way clearer view of the scene imo than the old sodium lighting. Maybe it's just brighter now.
3 replies →
I think we've learned a couple of times that lighting placement, temperature, and shadow-casting are not ideal [0]. Also some of the newer lighting does actually fade to a different color [1] so it's not just the base temperature of the new lights.
[0] https://en.wikipedia.org/wiki/Moonlight_tower
[1] https://sigostreetlight.com/blogs/common-quality-problems-in...
The posted article seems like credulous commentary, though.
I miss the aesthetics of the support for the street light themselves too. In Spain they used to be curved with a 'crown' shaped top, looking 'classical' and less hard for the brain as straight lines make the brain really tired. We are used to fractal and curved designs from nature, not to fake perspective points in every city full of straight lines.
These could just reuse the current LED lamps by just redesigning the socket. Altough the materials should be changed as the old ones (I think they were ceramic and/or concrete?) could cause serious harms if they felt over random people walking around. And, yes, they can even break concrete pavement like nothing.
I remember hearing a falling lamp+case near my home and upon falling to the sidewalk it sounded like a bomb, I am no kidding, even the floor vibrated and the windows nearly crashed. These things were really sturdy, either concrete or cement. I would love the same design but in magnesium, which can be lighter and maybe as durable, altough I know ceramic/concrete can withstand anything.
I'm sure tons of people along the way "noticed" but if you're selling LEDs or you're paid by the LED people to create marketing to convince people that LEDs are gonna save the planet, you're not gonna bring that up.
IDK if you've noticed but we are all lighting our house with bulbs that use 1/10th the amount of electricity as incandescents did. I like the color spectrum of a real lightbulb better, too, but not enough to pay 10x in power. I make up for it by using all kinds of random bulbs all over the place so that the aggregate light in the room fills more of the spectrum than if I coordinated them all to be the same.
The really awesome thing about the 1/10 power consumption is that the existing circuits/wiring/sockets now suddenly support 10x the light without burning down your house. I'm a sucker for well lit space and these lights are just heaven for me.
Did you try using high CRI LEDs with color remperature of 2700K–3000K? When I switched from halogen to LED I did just that and the difference is not noticeable, you'll have the same yellowish tint and very natural looking colours. Even with expensive bulbs, extra longevity covers for higher cost.
2 replies →
The problem is we went from a market that consisted of cheapo/good bulbs at various brightness levels to a market where Walmart and Home Depot have like 60 linear feet of bulbs.
There’s no standards and people are clueless and confused. There are awesome LEDs, but more often you see have harsh, terrible light.
>but we are all lighting our house with bulbs that use 1/10th the amount of electricity as incandescents did.
Yeah I know. I love it in my house.
On the industrial side, sodium vs LED is a much closer comparison generally than LED vs incandescent. LEDs kinda suck for high bay applications.
Depending on where you live the heating might be nice.
In the US people use roughly 10 000 kwh per year.
Say we have a 40 watt bulb, say it burns on average 5 hours per day or 200 wh. In 365 days that would be 72 kwh which at 16 cents per kwh is $11.52 or 0.73% of the annual power consumption.
Say one uses 5 light bulbs. Something around $57.60. Say leds use only 25% of the power = $14.40 for $43.2 saved.
Well over 10 cents per day.
What are you going to spend your 10 cents on? lol
How many life forms do we have to kill before cost savings aren't worth it?
Besides, we can have LEDs in better spectrums for under 1/5th the costs of incandescents. We just hired stingy motherfuckers and don't care about the repercussions of our decisions.