Unintended hazard: Energy-efficient traffic lights can't melt snow | Hacker News Reader

Unintended hazard: Energy-efficient traffic lights can't melt snow

news.yahoo.com

38 pointscwan23 comments

This is a lot like the conductive metal buttons the city installed earlier this year at a number of pedestrian crossings here in Ottawa. They've worked great all summer, they don't wear out as quickly because they aren't mechanical, but they're just now starting to realize that once February hits and it's -30C outside you'll have to take off your gloves and touch some metal to cross the street. Oh well, I guess the cost of progress is sometimes being stuck to a metal pole.

Here in Amsterdam we have something similar (a button that doesn't push-in) but they're made of plastic, work with gloves, and light up when they're pressed.

Maybe you could carry a steak around.

Wikipedia doesn't have a disambiguation page for "steak", and I am really guessing you didn't mean a thick juicy cut of loin from premium Australian beef, done medium rare.

If I carried that around, I would be melting the snow.

I think P meant steak, as you can use a piece of meat to trigger conductive switches...

Leaky Abstraction!... Well not really - just reminded me of it. Sometimes making the things simpler (e.g. consuming less energy) calls for unexpected effects.

"Sometimes making the things simpler (e.g. consuming less energy) calls for unexpected effects."

Simple is complicated.

I wonder how the rate of covering by snow compares with blown bulbs needing replaced, as both result in the lights not being visible. (Though I'm guessing it's more likely for more than one light to be obscured by snow than to be blown, which might makes things worse (or better?))

In areas where there is little or no snow then this would be an (un?)expected benefit of the change to more efficient lights.

Same thing with halogen vs xenon car lights. One of the reasons xenon kits are illegal in many countries, they lack wipers and xenon lights can't melt snow (they usually also lack lenses, hence they dazzle other drivers).

Accidents are terrible things, but I'm not exactly sure why to blame those traffic accidents on the lights instead of the drivers. First rule: drive as the driving conditions permit. Had it been a power-cut or a mist (making the traffic lights similarly unusable), would people still blame the lights if someone crashes their car? Unintended: sure. Hazard: quite possibly. Driving carefully: priceless...

If you can't see the lights you can misread the signals. I live in Green Bay, WI and I saw most of the lights along my morning route to school were covered on north/south lanes but clear on east/west. It was very very difficult to determine what light I had even using the east/west lights to rule out them having a green light. I had several close calls. Additional in Green Bay visibility was quite poor and the roads were dangerous.

As for people missing the signals, I have a theory. Everyone I know determines if they have a red, yellow, or green light by looking at the color of the light. (Bear with me here.) I look at the position of the light instead of the color. I am the only person I know with normal vision that does this. From the number of people I've asked, only those with colorblindness read lights by position. I would assume this means most people look for a light to find a stoplight. Given poor visibility the lack of a visible light means people won't see the signal.

Free feel to poke holes in my theory or ask me questions about my specialness with street lights.

The heater should trigger on the detection of signal light reflected from snow.

I wonder if a clear plastic shield coated in Teflon would work...

Teflon is not clear. Maybe really thin? But it's quite difficult to attach teflon to anything.

Or make the tubes (more) open at the bottom and tilt the lights a little bit.

Yep, that's how it's done with most traffic lights in central Europe, e.g. http://www.flickr.com/photos/30626457@N00/4580229/

I've never seen lights with that design obscured by snow, and many are LED based now.

Doesn't that very photo you link to show a light obscured by snow?

(The top one a little bit, and the middle one much more so. The bottom one is the clearest because the snow can't build up on the cover of the one below).

If you look at the next photo in the stream - http://www.flickr.com/photos/dustpuppy/4580359 you'll see the red light is still two-thirds visible. Whilst that's not perfect, it's better than nothing. Coverage of the amber (middle) light isn't much of an issue as it's used in transition between the main lights. In those conditions, not seeing the amber isn't going to need much of a behavioural change.

The problem is pretty well known, with (I believe) several companies selling heaters that activate in cold weather.

I was even able to find articles that mentioned the issue dating back to Q4 2000.

As such, I'm not sure why this is all over the internet today. Somebody ignored a well-known issue and bought the wrong product. It worked as expected.

Why bother with heaters? A plastic cap in front of the tubular 'hood' should work just as well and is a one-off cost. In the photo you can see the problem is the snow piling up inside the tubular shade. Cap the tube and gravity will do the rest.

Snow can be sticky and sticky snow would stick to a plastic window.

Notice the sign to the right of the signal. Even though it is a straight vertical surface it's covered as well. Blowing wet snow will stick to just about anything.

OK, heaters it is I guess. I grew up in a wet climate and when we got snow it was too heavy to stick to anything but the ground. D'oh, for assuming snow was snow.

Reply on news.ycombinator.com