Don Klipstein wrote:

In article , Pete C. wrote:
Tony Hwang wrote:

Nearby town of Banff installed LED street lights with solar panels.
Very cool looking light and it is cool running, no bugs get attracted
kep them clean. Cost a lot initially but for the long run, it's winner.
LED bulbs now are expensive but with time the price will come down.
I have a few small ones in the house, they use couple Watts per bulb.

I'd have to see those to believe them, unless they are the purely
cosmetic kind. I've yet to see any LED source that can compare to a 400W
HID source.

I would be glad to see HPS lamps go. LED ones appear to me to be very
expensive and maybe not the best deal for the taxpayers paying for them.
However, I would not mind replacing a 400 watt HPS with a 175W or 250W
metal halide.

A 175-250 watt metal halide will illuminate streets close to as well as
a 400 watt HPS does, for 2 reasons:

1. HPS lamps tend to make red, green and blue objects look dark.

2. At typical streetlighting illumination levels, human vision is in
"mesopic" mode. That is when both scotopic vision and photopic vision are
significantly functioning. Scotopic vision adds a senseation of
illumination in this case. A metal halide lamp produces many times more
light that is favorable to scotopic vision than an HPS lamp of same
photometric output.

Then again, a lot of streets are illuminated more brightly than they
need to be. 100 watt metal halides could work just fine!

On that last point, many streets would do fine with no streetlights at
all. The only areas that have any real need for street lights are in
urban areas with nighttime pedestrian activity, and in rural areas only
in the immediate vicinity of traffic lights and significant
intersections.