
LED stoplights not emitting enough heat to melt snow covering the lights - kyleblarson
http://www.twincities.com/2017/12/05/snow-encrusted-led-stoplights-create-havoc-in-oak-park-heights/
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codewritinfool
This was news years ago. Cities were adding heaters to lights to solve the
problem. Here's one article from 2009: [https://boingboing.net/2009/12/17/led-
traffic-lights-d.html](https://boingboing.net/2009/12/17/led-traffic-
lights-d.html)

~~~
Johnny555
And there's a commercial off-the-shelf solution:

[https://products.currentbyge.com/transportation-
lighting/led...](https://products.currentbyge.com/transportation-lighting/led-
traffic-signals/gtx-heated-shell)

(which only uses 30W for the heater, so it's still far more efficient than the
old-style ~150W incandescent.

If the Minnesota DOT wasn't aware that this could be a problem, they are
incompetent.

It's even a problem with little used incandescent lights... on a street where
the light is nearly always green, the red light can still ice/snow over and
not have time to melt during brief red intervals in cold weather.

~~~
jws
The 30 watt heater should also last the life of the LED bulb, saving the
maintenance every year or so to replace the traditional lightbulbs.

For most climates, designing in a temperature sensor to keep the light a
little above freezing would pay back in well under a year of power savings.

Update: Did a quick search for LED traffic balls… looks like about 10 watts
when on, and I don't see any of them integrating heaters. Market opportunity!
Make LED traffic balls but add a tiny micro controller, thermistor, and a
heating element, maybe attached to the existing heat sink and you are set.
(Yes, attaching a heater to the heatsink sounds counterproductive, but you
will be running it when the heatsink is nearly freezing so the LEDs will still
have plenty of thermal differential to dump their waste heat.)

~~~
1stranger
I'm not surprised there are no LEDs with heaters. Seems like it would be
integrated into the housing/lense.

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cr0sh
It'd be a bit complex, but why not spin the lens with a motor at high speed,
like a clear view screen on a ship?

[https://en.wikipedia.org/wiki/Clear_view_screen](https://en.wikipedia.org/wiki/Clear_view_screen)

Actually, maybe it would be simpler than I first thought:

1\. Mount the lens using v-shaped rollers on the edges (three would be
sufficient)

2\. Along the edge of the lens, attach permanent magnets - a ring of magnets
with alternating polarity, NSNSNS...

3\. Coils along the edges (might even be able to do it with printed circuit
coils) energized, interacting with the magnets to spin the lens.

Essentially, you're making the lens operate as the rotor of a high-speed
brushless rotor. One could probably trivially implement a prototype of this
using hardware store parts over the weekend.

In fact, this seems like such a simple solution, I wouldn't be surprised if
there isn't a patent already out there describing it.

If not - consider this submission of mine "prior art" I guess - anybody at YC
want to fund a startup? /lol

~~~
saas_sam
Makes sense, but wouldn't it be cheaper to stick a motor on the light to
vibrate and detach the snow/ice?

~~~
Johnny555
In cold weather a car windshield can ice over at 60mph without defroster heat,
I don't think a vibrating light housing will stop freezing rain from building
up.

There is one thing that is proven to work in a wide variety of situations, is
easy to supply, has no moving parts: heat. And there are already solutions out
there to provide heat.

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tyldum
It is a problem on modern cars as well, since most have LED tail lights. They
get covered in snow and become invisible.

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choward
Reminds me of this: [https://xkcd.com/1172/](https://xkcd.com/1172/)

