street lighting brightness increased over time? 1

[EvilJeb]

I'm wondering if anyone has specifications on the average street light of 25 years ago, vs. today (for towns that are still using HPS lights - I know LEDs are totally different and usually much brighter).

I'm trying hard to keep all this relevant to my question. Basically, I moved to a town in 2002, and the streetlights still all seemed about as bright as the ones I remembered from growing up in the 1980s, with the exception of a few extra-bright ones. Everyone used HPS lights then, and most towns around here still do, but the new ones seem brighter, and I am trying to quantify the difference. For a while I thought it was just the difference between old lamps and new, as they seemed brighter after a replacement. But gradually the new ones became even brighter, and, maybe around 2010, it became clear to me that either there is a higher-wattage bulb being used, or a higher level of efficacy of modern HPS bulbs, or both. Around 2015, it became clear to me that even brighter bulbs were being used everywhere, and I hate the new ones so much that I pretty much stopped reporting burned-out ones. Every time the city replaced one, they put in one with too much light output.

After 15 years of living there, a little over a year ago I moved back to the area where I grew up. My old neighborhood still has street lights in the same locations, but they are definitely all brighter than they used to be.

So, can someone quantify the difference for me? Point to specifications for "standard" HPS lights of 20 years ago, vs. now? As I mentioned, I hate the new ones, but I can't really fight against this without understanding the exact problem.

And now they're going to new LED lights, which are even worse. The white color creates a glare that makes lane markings hard to see on rainy nights. An LED streetlight is what prompted me to finally ask this question that I've been planning to ask for years: yesterday, next door to my house, they installed an insanely-bright LED street light. I'm definitely going to fight it. It shines in my back yard, and I want my back yard to be dark at night.

 

[3DDave]

Not only are there more photons coming out, they are coming out in the parts of the spectrum that retinas are more sensitive to and in greater quantities in those parts of the spectrum they aren't - basically pushing farther into green and blue. The seeming goal is to produce daytime levels of illumination without the advantage of being produced from a great distance, so no matter where the observer is the light is essentially shining directly at them.

As an aside on this, the company cafeteria used mercury vapor bulbs; it was weird because the lamps were individually terrifically bright, but the cafeteria seemed dark. I brought in a cheap ($10) spectrometer and saw that there were a few narrow peak colors and nothing in between. The colors were enough to appear to be white, but since they were so narrow in spectrum, nearly nothing in the cafeteria reflected those colors, so they all seemed dark.

https://en.wikipedia.org/wiki/Mercury-vapor_lamp#Color_considerations

Note the "bloodless corpse" reference.

 

[IRstuff]

Most everyone else wants their streets to be better lit, since that makes them feel safer and is probably somewhat of a crime deterrent. Since LEDs are way more efficient, the cities get the added benefit of having brightly lit streets with comparable or lower power consumption as well as less bulb maintenance.

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[dpc]

The Illuminating Engineering Society (IES) publishes a handbook on lighting that covers recommended roadway lighting illumination levels. The recommendations are based on a footcandle level, generally not tied to a particular technology, although the frequency spectrum of the lighting is a factor as well. Keep in mind that there are differing categories of "streets' each with differing recommendations. I don't think the recommended illumination levels have increased much over the years, but I haven't looked at the standard in a while. If you check websites for fixture manufacturers, you may be able to find recommended IES levels. Check Holophane.

Also, most light sources tend to put out less light over time - including LEDs. So any NEW streetlight installed will always be brighter than one that has been in service for a few years. HPS lamps have fairly pronounced output drop-off. In addition, as the fixture gets dirty, effective lumen output goes down.

It is possible to have "blinders" and shields place on a portion of the streetlight to reduce the light output in a particular direction. We have one like that on our block that must have been done based on someone's complaint.

Good luck.

Dave