When used in traffic signals, the lights don't get warm enough to melt snow.
The snow obscures the signal and people die.
"Cities around the country that have installed energy-efficient traffic
lights are discovering a hazardous downside: The bulbs don't burn hot enough
to melt snow and can become crusted over in a storm - a problem blamed for
dozens of accidents and at least one death."
Some cities are considering hiring midgets to sit atop the signals with
hair-dryers and long extension cords to keep the traffic signals clear.
(Some species of monkeys could be trained to do the job, but the training
time would take too long to be effective this season.)
I can see a couple of ways to prevent the problem and one is to use
the type of heater that is used in outdoor CCTV cameras. Another
way would be a simple snap on clear plastic cover that would prevent
snow from getting into the hooded area. Oh yea, teeny little windshield
On Wed, 16 Dec 2009 11:14:28 -0600, The Daring Dufas wrote:
Yes, that would work. Wouldn't need much heat at all, either, I suspect.
Problem might be designing something and getting it all properly safety
tested before it can be used out in the wild; I expect LED lights have
been in the pipeline for a few years and for some reason some idiot never
thought of the cold-weather issues.
As it turns out, I have yet to see even one LED traffic signal
effectively obscured by snow or any other form of water in Philadelphia
and that city's suburbs. It does snow there, with only one of the past
135 winters there officially having only a trace of snowfall, an average
one having about 21-22 inches of snow, and the worst one of the past 135
(1995-1996) having 66-67 or so inches of snow, including over 30 inches in
a record-breaking storm. And by-and-large, northwestern parts of the city
that I grew up in and most of the city's northern and western suburbs that
most of my family has lived in since 1991 and that I know well usually
get substantially more due to higher elevation.
And quite the share at least of the snow there is the wet sticky kind
blamed for obscuring LED traffic signals. And most of it falls with wind
in the range of "moderate breeze", "fresh breeze" or "strong breeze".
- Don Klipstein ( email@example.com)
I used to live in Bolingbrook, IL, a
southwestern suburb of Chicago. All
the traffic light are LED. I have seen
them obscured when there is a wind
blown wet snow. But, it usually doesn't
last long, so I don't know how
much an issue it really is. BTW, they
also had UPSs on every traffic light,
so power failures didn't affect the
lights. I don't know how many hours
the lights would keep working.
On Thu, 17 Dec 2009 21:24:20 -0500, Art Todesco wrote:
Y'know, I think most of ours in town here in northern MN are incandescent
still, but I've still seen them full of snow. I think all it takes is
for there to be a little space open above the snow pile; the cold air
gets in behind the pile and makes the heating effect from the bulbs
What they perhaps need are separate heaters at the bottom of the shrouds,
but I'm not sure how that could be (reliably and relatively
maintainance-free) switched so that the heaters only ran when they needed
to. Perhaps there's some way of detecting how much light from the bulb is
being reflected back (due to snow build-up) and tripping the heater that
I would expect it wouldn't be that difficult to install an optical
sensor at the end of the hood looking back at the light and use that to
switch on a heater if it did not detect sufficient brightness when the
signal light was on. No extra energy use unless there actually was snow
obscuring the signal. Probably around $20 manufacturing cost, so sell
for $200, a fairly insignificant cost given what the signals themselves
cost. Also only needed in climates that have blowing sticking snow.
No point in heating all the time, or even just when it's cold. Much
better to heat only when it's cold and something (snow) is obscuring the
light. The minimal cost of the extra control components will be far
outweighed by the lifetime power savings of only having the heater
active during sticking snow events.
But the heat would serve to incubate the eggs, leaving momma free to flirt
with the flight. The chicks would then end up as unsupervised avians leading
to the spread of "feather delinquency."
What the heck's wrong with the "midgets with hair-dryers" proposal?
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