Comment by teslabox

3 days ago

Blue-white LEDs have become the replacement for High Pressure Sodium [HPS] traffic lights because that's what the LED light companies have to sell. In the early years of the transition to LED streetlights they had to sell blue-white LED streetlights because warmer LEDs were not competitive with HPS on the basis of lumens-per-watt.

Most of the people who understood the advantages of blue-free amber HPS light over white metal halide lights retired, and this little tidbit of information didn't get passed to the next generation of city employees.

> and because people do not care.

People care, but they don't know why they hate the blue-white LED replacement lights. I've complained to the city about their new lights, but have not gotten any responses about why they haven't deployed LED lights with a safe spectrum of color.

This comment about unsafe blue-white headlights got a few upvotes: https://news.ycombinator.com/item?id=42444111

9 comments

teslabox

Reply
Qwertious  3 days ago

Blue light is safer for cars - it gives slightly faster reaction times, and lower the chance of drivers falling asleep.

The problem is that for pedestrians, the reaction-time is irrelevant, they're butt-ugly, and plenty of people go on night walks because they can't sleep but want to.

Half of this article is basically about cities being overly car-centric.

  • reddalo  2 days ago

    In some ways, car-centric cities are like that because people don't care. "I'll just take my car, whatever". They don't care about traffic, pollution, accidents, etc.

    • Vampiero  1 day ago

      Or maybe they care about getting to their destination in time and not wasting half a day just going from point A to point B on foot/by (shitty) public transportation, or they'll be fired.

      Daily reminder that we live under capitalism where you're not allowed to just "take your time".

  • teslabox  3 days ago

    I’m not well-read on the old lighting research, but I’ve come across some explanations for why humans actually do much better with amber outdoor lighting than white. One of these points relates to how our pupils expand and contract with the amount of light available.

rob74  3 days ago

My impression was that HPS lighting became so widespread not because of the supposed advantages of its light spectrum, but because it was simply the most light-efficient technology available at that time. Here in Germany, only main/multilane streets requiring more lighting were using HPS, residential streets mostly had lamps with white fluorescent lights, so switching those to LEDs wasn't as much of a change. But still, I'm wondering: what about curtains, window blinds etc.? It's not as if people are forced to endure the intrusion of street lighting into their bedrooms?

  • crazygringo  2 days ago

    > But still, I'm wondering: what about curtains, window blinds etc.? It's not as if people are forced to endure the intrusion of street lighting into their bedrooms?

    Of course. But that's the problem -- now black-out curtains are required. And maybe you hate those because you really enjoy waking up with the sun streaming in, and now you have to wake up every morning in blackness until you go open the curtains.

    The onus shouldn't be on the residents. It's the same as saying, sure it's noisy but why don't you just wear noise-canceling headphones all day long?

    Government services exist to serve the people, not make the people work around them.

  • teslabox  3 days ago

    Low pressure sodium lights were more efficient, but they emit a single wavelength of orange light. These lights were strongly disliked by people who liked to admire their car in the streetlights (I suppose).

    > residential streets mostly had lamps with white fluorescent lights,

    … they used CFLs? The spiral fluorescents were invented in the 1980’s, I guess. I speculate the residential street lights used mercury vapor bulbs, which had a longer expected lifespan than fluorescents.

    > But still, I'm wondering: what about curtains, window blinds etc.?

    You need a good blackout curtain to deal with light pollution through your window.

    • flyinghamster  2 days ago

      Decades ago, my junior college's parking lot was lit by low-pressure sodium lighting. I recall the light being an absolute monochrome yellow, to the point that you had to be careful to remember exactly where you parked your car, because you weren't going to find it by color.

      I can't vouch for Germany, but there used to be long, high-output fluorescent tubes and fixtures for street lighting in the US. They seem to have largely disappeared by the 1980s. They weren't very common, but some cities used them. They tended to be used on main streets when I saw them.