Like most of us, I am coping with the recent Midwest snow storms as best as I can. But I have wondered something for some time now.
Why don’t we just have heated streets–and driveways for that matter? We have zillions of miles of pipes and cables already running thru our streets. Why not heating coils? It wouldn’t take too much energy, I would think. Just like your rear window defrosters, it only has to raise the temperature above freezing. And surely it would easier–and more cost-effective–than all the money we spend on snow plows and rock salt.
Where am I wrong in this? And why hasn’t anyone else ever thought of this?
:):):)
P.S. I primarily submit this to the SDMB. But I offer it to Cecil Adams as well:).
[ul]
[li]Frost depth varies across the country. Those “zillions of miles of pipes and cables already running thru our streets” are below frost depth. How do you expect to heat the road when frost depth in Minnesota ranges from 40-60 inches in winter?[/li][li]I can take you to lava tubes in Washington State where it’s 100*F at ground level on a hot summer’s day, but five feet below that in a lava tube it’s solid ice a foot thick. (Sorry I can’t give you a cite. Some exact locations are deliberately not on public maps.)[/li][li]Anaheim, California, is burying its entire power transmission system underground. It will take 50 years and cost $3 million a mile.[/li][/ul]
A while ago there was some guy selling the idea of solar panel roads. There were a few very good scientific debunking of the concept he was selling. He made the claim that the solar roads could heat themselves thus melting the snow and eliminating the need for plowing. The scientific conclusion was it would take more total energy to melt the snow then the totality of energy required to use equipment to move it.
I won’t pretend I’ve done the figures. But my intuitive thought would be that this idea would take a huge amount of energy.
The other problem is that when you melt snow, it doesn’t disappear. It turns into water. And that water is just going to flow to someplace where you haven’t heated the ground and turn into ice, which is generally a worse problem than snow is.
They are generally a clear indication the home owner has money to burn. A few of the properties I deal with run them. They are enormously costly. 30-50 watts per square foot. A small driveway in my area can cost a $1000 bucks a year to keep clear of snow with this method. Paying someone to plow or shovel the same driveway would cost less than half that per year. They are nice though, never need to worry about slipping in those driveways.
I’d think conduction to the rest of the environment would be the biggest energy sink. Melting ice takes a lot of energy, but unless it’s snowing constantly, once it’s melted (and transported away in your new, heated drainage system), it’s gone. Heat loss to the environment will be constant and high, unless you insulate the entire road with an insulation scheme that can stand up to the forces of heavy trucks.
I have seen heated driveways and heated sidewalks. They are neat. I worked in a place that installed a heated driveway–it went down into the company parking garage and was a bitch to keep clear of snow. Probably saved the company $$$ in repair costs.
I used to work on a campus that had some kind of hot water line going right under a couple of the larger sidewalks. I don’t know if they intended it, but those were always, always clear of snow.
Also the old downtown 16th street in Denver, before the mall, had some kind of underground pipes that heated it in places, which was very convenient as tall buildings block the sun downtown so the snow doesn’t just melt.
I actually think some kind of solar panel could work as a snow melter, if the street in question had access to the sun. Of course, if the sun was shining on the street the snow would probably melt anyway…
Yesterday, in response to a weather thread I discovered for the first time in my life that sports pitches have had Under-Soil Heating ( and God Knows why ); in England at least since 1958.
This seems an extension. Whilst I personally can see slight flaws — for instance the run-off from all the melting snow that nature purposed to land and stay — the energy bit may not be that onerous in maintenance: use Geo-Thermal instead of Solar.
Edinburgh had one of it’s main streets heated for years, starting in 1959*. It was quite a steep hill (the Mound, connecting the Old and New towns) and very treacherous when icy. So they installed under surface heating they could switch on if necessary to prevent it icing up in winter.
It worked fairly well but not so well they were willing to spend money repairing it after it started needing serious attention to keep it working properly. I think the last time it was used at all was back in the 1970s, but info about it seems quite scarce.
*the online discussion linked to from this page puts it at 1959, not 1955 as the page states.
I stayed in a condo in the mountains of Colorado where the whole neighborhood had heated streets. It was really nice. They had a very good drainage system to keep the runoff from being a worse problem somewhere else. We were actually able to walk barefoot from the hot tub back to the condo when it was 0 degrees outside.
