

The Unintended Negative Consequences of LEDs - cwan
http://freakonomics.blogs.nytimes.com/2010/01/06/led-astray/

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zyb09
The issue was already discovered a month ago and it's not 'consequences' but
one single consequence. Also the statement

> None of the proposed solutions are foolproof

is just simply wrong. Traffic lights will be upgraded with little heating
systems (coil/wires) and everything will be fine.

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maw
If so, will they still be cheaper to operate? I can buy that they'll still use
less energy on net, but that isn't the only concern here.

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wildwood
If the heating element is thermostat-driven, and not on all the time, then
yes.

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ars
Hopefully not a thermostat but rather a proximity or a frost sensor.

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evgen
No, use a thermostat. It is much simpler, less prone to errors, you only need
one per light housing, and the energy cost required to keep the shrouds above
34 degrees is quite insignificant.

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pavel_lishin
You could probably get away with having one per block; aren't most traffic
lights all connected? Or have I just been watching too many movies where
hackers take over streetlights?

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evgen
Putting one per light housing means it gets added at the manufacturer and you
don't need to do any additional wiring or setup at installation time.

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mnemonicsloth
This article got written because economists have a limited vocabulary for
talking about design.

If you build a machine to solve a problem, and the machine doesn't act the way
you want it to, that's a _bug_. Fixing bugs is easier than starting over would
be. Bugs that make you wonder are called _design flaws_.

You don't get _unintended consequences_ until your system works, and things
change in your environment (or maybe with your users) because of the way it
works. Unintended consequences are hard to fix because they only show up in
systems that are already doing what you want.

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aminuit
There is a good point in the comments that isn't made in the article. Unlike a
traffic light outage due to power failure, the ice buildup may only affect one
of the signals, so the conventional rule to treat a dark traffic signal as a
four way stop fails. One person may see a green light, while another driver on
a perpendicular course stops at the affected light, but then enters the
intersection because he expects the other driver to stop.

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maukdaddy
You should never enter an intersection "expecting" another driver to stop
under those kind of circumstances. After watching the driving abilities of the
average American, I would actually wait at the intersection until no cars are
in sight to continue on.

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mechanical_fish
Congratulations, you are officially qualified to drive in Massachusetts. ;)

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sophacles
Maybe they should sell led traffic bulbs with resistive wires to generate
heat, like the rear-windshield defroster. They could be switched on during
snow. Still saves a ton of money/energy.

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noodle
i'm sure they will, they probably just haven't had the time to produce and
sell a solution yet. it hasn't been long since they discovered the problem.

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Retric
It's a well known and solved problem, most areas are not willing to pay extra
to have it installed when it's only a problem for a few days a year or even
decade.

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mattmaroon
This seems silly. "Heating up the LEDs would help defeat the purpose of saving
energy". Not if you only heat them when they need heated, which I imagine is
trivial to detect. Even then you've got a bulb that runs at the same energy
usage during the winter as the rest, and then at a lower rate for 10 months
per year.

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ajross
Not even "during the winter". You only need to run the heater during active
snow or ice precipitation. That's what, a few dozen hours a year in most
areas?

~~~
mattmaroon
Yeah I was just thinking temperature detection or just a schedule would be
very cheap and easy to implement.

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mhb
De-icing system for traffic signals patent:

[http://www.google.com/patents?id=8dJ_AAAAEBAJ&printsec=a...](http://www.google.com/patents?id=8dJ_AAAAEBAJ&printsec=abstract&zoom=4&source=gbs_overview_r&cad=0#v=onepage&q=&f=false)

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blahedo
It seems strange that all the "solutions"---heating coils, diodes, whatever---
seem to presume that the basic form factor of the light system would remain
unchanged. But wouldn't it be easier to solve if you just rethought the shape
of things? Instead of a three-light assembly with hoods over each light (where
snow can build up on top of the hood for the next lower light), just reshape
the traffic signal as a box with the lights on the back, the four sides opaque
(to block glare and peripheral view), and the front side transparent plastic
of some variety? There are surely engineering issues there too (like
preventing glare off the clear plastic), but it seems like a more stable
system, no worries about snow accumulation, and it's probably cheaper to
manufacture too.

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nazgulnarsil
sunk costs. infrastructure changes would cost an order of magnitude more than
a tweak.

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teeja
Upvoted for the linked article (PDF) about horses/manure in the 1800s->1905

[http://www.uctc.net/access/30/Access%2030%20-%2002%20-%20Hor...](http://www.uctc.net/access/30/Access%2030%20-%2002%20-%20Horse%20Power.pdf)

well worth reading for it's analysis of all the problems with horses that the
CAR solved (and, as always, it created new ones) -- like piles of manure 40-60
feet high in cities! Now that problem's limited to D.C.!!

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hoggle
This is really funny maybe U.S. infrastructure decision makers should buy
european technology, because a simple combination of sensors(temperature and
or light)/heating coils would solve all of these problems pretty easily.

