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I've been watching some of the neighborhoods undergo early adoption of LED street lamps. It's been interesting. The new lamps are definitely much bluer than th

by 60654 9y ago

I've been watching some of the neighborhoods undergo early adoption of LED street lamps. It's been interesting. The new lamps are definitely much bluer than the current sodium lights, which gives the street a different, unfamiliar feel. The article suggests the city ultimately adopted 3000K lamps, but it definitely feels like the pilot program used 4000K ones, they looked very cool. Another interesting development with these so-called "smart lights" [1] is that the city can potentially modulate brightness on a street-by-street basis, and asking different neighborhoods to weigh in on where they want the lamps to be brighter (or maybe, if they want them dimmer on side streets etc). This sounds like a very good change - customizing street lights based on neighborhood requirements is a very nice development! [1] https://www.cityofchicago.org/city/en/depts/cdot/supp_info/chicago-s-smart-lighting-project.html https://www.cityofchicago.org/city/en/depts/cdot/supp_info/c...

pducks32 9y ago
Yea I live on a street with the pilot program and no doubt they were much brighter than 3000K. They were very blue but I really like them. It gave my neighborhood a more small town feel if that makes any sense.
- colechristensen 9y ago
  3000K is about color not intensity
  - icelancer 9y ago
    Not in perception, however.
    - kakarot 9y ago
      Unfortunately, using "brighter" here is still completely incorrect and parent is right for correcting him.
      - weberc2 9y ago
        I always perceive blue light as brighter. I dabble in indoor lighting, and warmer (bluer) bulbs always seem brighter. Unless the brightness of fluorescents changes with the color temperature, I'm inclined to agree with the original comment. Besides, nit picking is rarely useful.
        Karunamon 9y ago
        There's actually a reason for that - bluer light reflects in front of the retina rather than focusing onto it, and so it scatters throughout the eye more than other wavelengths, especially when there's little ambient light. It's called the Purkinje effect. The light doesn't have greater luminosity, but it is perceived as brighter. https://en.wikipedia.org/wiki/Purkinje_effect https://en.wikipedia.org/wiki/Purkinje_effect https://blog.codinghorror.com/blue-led-backlash/ https://blog.codinghorror.com/blue-led-backlash/
        justin66 9y ago
        Thank God you cleared that up.
        kakarot 9y ago
        Who is nitpicking here? My parent? Me? You? We are all just trying to help someone be more correct. For me at least, it isn't because I wish to nit pick. Perhaps you could have had a more useful comment by not adding your personal anecdote and instead providing a citation? The other responder to your comment is correct. It is entirely perceived and there is no real change in luminosity and thus brightness is the incorrect term. I was offering my insight as both a graphic designer and amateur technical 3D artist with solid grasp of color theory and optics. Meanwhile you just butted in to tell me I'm wrong and I shouldn't tell other people they are wrong. That's a conflicting position, and furthermore the person I was replying to was correcting someone else, and I was clarifying for both of them. So I really don't know why you felt the need to comment in the first place.
        9y ago
  - pducks32 9y ago
    I know sorry wasn't thinking.
- deleted 9y ago
  [deleted]
inlineint 9y ago
But AFAIK LED brightness is usually controlled by pulse-width modulation, which is essentially adding flicker. There are people with flicker sensitivity that have headaches when exposed to flickering light. A link to a HN discussion that touched the problem of PWM and flicker in the comments: https://news.ycombinator.com/item?id=13330611 https://news.ycombinator.com/item?id=13330611
- Baeocystin 9y ago
  There's no reason to use a low-frequency carrier for PWM. Drive the LED at a multi-kHz speed and it's fine.
Shivetya 9y ago
In my subdivision in a metro Atlanta county I the local power cooperative is replacing failed halogen/sodium/etc street lamps with LED. The orange lights provided good light but the same pole with a LED now lights up the area as if it were full moon or close to it. You cannot look directly at these lights where you could at the older lights. I have an orange lamp in the corner of my lot but the nearest LED is about three hundred feet away and it still puts out more. One oddity which I cannot completely attribute to the lights. Birds in our holly bushes were singing at very odd hours for the first weeks or two but have apparently moved to bushes and trees in the back yard.
- mholmes680 9y ago
  I wonder what the effects on other animals will be. Maybe this is the thing thats killing the honeybees. Ok probably not, but if humans can be out of whack from this, I wonder what other creatures will start to lose sleep - or will nocturnal animals sleep in all night?
  - DanBC 9y ago
    I'd be interested to know what the effects on bugs, and animals that feed on bugs, will be. Will the new lights attract more bugs? Will animals that feed on bugs be attracted to them?
abcanthur 9y ago
All color considerations aside, one thing I find quit discomforting (first subconsciously, until I put my finger on it, and now even worse) is that led lights are very very often a rectangular array of lighting elements. So instead of a point (or at least a large diffuse, continuous "point" in various bulb constructions) there are between 25-64 points of light in a 6"x6" area. From a 20' light pole, looking at the shadow of your hand on the sidewalk, you see (let's say) 36 different vague shadows, in a rectangular array, with a disfigured hand shaped, darkest shadow in the middle where the shadows all overlap. Truly, it can be dizzying if you try to focus on the shape of the shadow from a single object. Tree canopies become shifting fields, everything gets a blocky 16bit feel to it. I'm only human, but I can imagine some animals are well tuned to single point shadows and this effect might really throw them off. (Interesting aside, I first noticed this while leaving LACMA (LA County Museum of Art) where the pure Instagram gold of Chris Burden's collection of old LA street lamps tightly packed, produces the same effect)
- nine_k 9y ago
  Does it differ too much from vague shadows on an overcast day? I'd say 64 close-by shadows look more natural than more distinct 4, which I could clearly see with regular point-source lamps on tall poles.
- weberc2 9y ago
  Presumably this can be ameliorated by refracting the light with a plastic screen?
- sorenjan 9y ago
  Yes, those shadows[1] are weird and feels a bit like low res shadow maps in games. Hopefully they start using diffusers in the future. [1] https://pbs.twimg.com/media/CIUkuDmUcAAqiF7.jpg https://pbs.twimg.com/media/CIUkuDmUcAAqiF7.jpg

by 60654 9y ago

pducks32 9y ago

Yea I live on a street with the pilot program and no doubt they were much brighter than 3000K. They were very blue but I really like them. It gave my neighborhood a more small town feel if that makes any sense.

colechristensen 9y ago
3000K is about color not intensity
- icelancer 9y ago
  Not in perception, however.
  - kakarot 9y ago
    Unfortunately, using "brighter" here is still completely incorrect and parent is right for correcting him.
    - weberc2 9y ago
      I always perceive blue light as brighter. I dabble in indoor lighting, and warmer (bluer) bulbs always seem brighter. Unless the brightness of fluorescents changes with the color temperature, I'm inclined to agree with the original comment. Besides, nit picking is rarely useful.
      - Karunamon 9y ago
        There's actually a reason for that - bluer light reflects in front of the retina rather than focusing onto it, and so it scatters throughout the eye more than other wavelengths, especially when there's little ambient light. It's called the Purkinje effect. The light doesn't have greater luminosity, but it is perceived as brighter. https://en.wikipedia.org/wiki/Purkinje_effect https://en.wikipedia.org/wiki/Purkinje_effect https://blog.codinghorror.com/blue-led-backlash/ https://blog.codinghorror.com/blue-led-backlash/
        justin66 9y ago
        Thank God you cleared that up.
      - kakarot 9y ago
        Who is nitpicking here? My parent? Me? You? We are all just trying to help someone be more correct. For me at least, it isn't because I wish to nit pick. Perhaps you could have had a more useful comment by not adding your personal anecdote and instead providing a citation? The other responder to your comment is correct. It is entirely perceived and there is no real change in luminosity and thus brightness is the incorrect term. I was offering my insight as both a graphic designer and amateur technical 3D artist with solid grasp of color theory and optics. Meanwhile you just butted in to tell me I'm wrong and I shouldn't tell other people they are wrong. That's a conflicting position, and furthermore the person I was replying to was correcting someone else, and I was clarifying for both of them. So I really don't know why you felt the need to comment in the first place.
        9y ago
- pducks32 9y ago
  I know sorry wasn't thinking.
deleted 9y ago
[deleted]

inlineint 9y ago

But AFAIK LED brightness is usually controlled by pulse-width modulation, which is essentially adding flicker. There are people with flicker sensitivity that have headaches when exposed to flickering light. A link to a HN discussion that touched the problem of PWM and flicker in the comments: https://news.ycombinator.com/item?id=13330611 https://news.ycombinator.com/item?id=13330611

Baeocystin 9y ago
There's no reason to use a low-frequency carrier for PWM. Drive the LED at a multi-kHz speed and it's fine.

Shivetya 9y ago

In my subdivision in a metro Atlanta county I the local power cooperative is replacing failed halogen/sodium/etc street lamps with LED. The orange lights provided good light but the same pole with a LED now lights up the area as if it were full moon or close to it. You cannot look directly at these lights where you could at the older lights. I have an orange lamp in the corner of my lot but the nearest LED is about three hundred feet away and it still puts out more. One oddity which I cannot completely attribute to the lights. Birds in our holly bushes were singing at very odd hours for the first weeks or two but have apparently moved to bushes and trees in the back yard.

mholmes680 9y ago
I wonder what the effects on other animals will be. Maybe this is the thing thats killing the honeybees. Ok probably not, but if humans can be out of whack from this, I wonder what other creatures will start to lose sleep - or will nocturnal animals sleep in all night?
- DanBC 9y ago
  I'd be interested to know what the effects on bugs, and animals that feed on bugs, will be. Will the new lights attract more bugs? Will animals that feed on bugs be attracted to them?

abcanthur 9y ago

All color considerations aside, one thing I find quit discomforting (first subconsciously, until I put my finger on it, and now even worse) is that led lights are very very often a rectangular array of lighting elements. So instead of a point (or at least a large diffuse, continuous "point" in various bulb constructions) there are between 25-64 points of light in a 6"x6" area. From a 20' light pole, looking at the shadow of your hand on the sidewalk, you see (let's say) 36 different vague shadows, in a rectangular array, with a disfigured hand shaped, darkest shadow in the middle where the shadows all overlap. Truly, it can be dizzying if you try to focus on the shape of the shadow from a single object. Tree canopies become shifting fields, everything gets a blocky 16bit feel to it. I'm only human, but I can imagine some animals are well tuned to single point shadows and this effect might really throw them off. (Interesting aside, I first noticed this while leaving LACMA (LA County Museum of Art) where the pure Instagram gold of Chris Burden's collection of old LA street lamps tightly packed, produces the same effect)

nine_k 9y ago
Does it differ too much from vague shadows on an overcast day? I'd say 64 close-by shadows look more natural than more distinct 4, which I could clearly see with regular point-source lamps on tall poles.
weberc2 9y ago
Presumably this can be ameliorated by refracting the light with a plastic screen?
sorenjan 9y ago
Yes, those shadows[1] are weird and feels a bit like low res shadow maps in games. Hopefully they start using diffusers in the future. [1] https://pbs.twimg.com/media/CIUkuDmUcAAqiF7.jpg https://pbs.twimg.com/media/CIUkuDmUcAAqiF7.jpg