It's done here and there but it's expensive.

1. The wiring or piping can get damaged. When it does, it will leave that street with no protection, and repair will cause disruption to traffic, not to mention the disruption the initial installation would cost. Plus they would be in the way of utilities under the ground, in case you have to get at them to maintain them.

2. In most places the power is not there. Despite having possible ready access to energy, the capacity may not be there in the system to support on-street melting, so that would need upgraded. If you choose a steam or liquid piping system, you will have to build steam plants, and that means taking space from some other purpose. Not to mention that energy needs paid for.

3. Electrical systems will create some degree of hazard, as may steam or other liquid systems.

4. You have to account for water runoff and where it will go, and keep those systems clear also.

Yes, crrent snow removal systems aren't free either, but you have to consider the capital and ongoing costs of one vs the other.

Nice, but expensive, energy intensive and so-far they're high maintenance.

http://www.whynot.net/ideas/4619

Maybe tunnel roads would work better.

Maybe the best way to heat roads is to use geothermal heat. Pipes would run under the pavement, then deep into the ground. A fluid (nonfreezing) would run through the pipes. During the summer, the system could actually cool the road, which might make walking more confortable. This would also heat the rock down in the ground. During icy winter conditions, the same heat would be brought back up up to warm the road. It may not work all winter long, but if it work for even half the winter it would save a lot of plowing.

Of course, it would be expensive to install and it would still require energy to pump the fluid. But it would take a lot less energy than other methods of heating. They already use this method in Iceland, but they have steaming geysers which makes it much more effective.

Appreciate the feedback. Interesting to know it's already done in some places. Couple of comments:

1. I'm not familiar with the cost of the materials that would be best in terms of conducting heat and I don't have the engineering background to figure out the best layout (spacing, etc).

2. Regarding the power requirement, I have a couple of thoughts to reduce this cost. First of all, the required temperature only needs to be high enough to melt the snow/ice and/or keep it melted. Secondly, one could install green power generators. Even if they are insufficient to handle the entire power requirement, wind or solar power generation might be able to provide a significant amount of required power.

3. My recommendation would not include digging up existing roads. But new roads and roads requiring repaving would certainly be candidates. Furthermore, I'd prioritize to address bridges first (most major bridges do have current power supplies for street lighting).

For bridges over rivers, you could use coils that go under the water similar to a water-source heat pump to warm the fluid. You shouldn't use an open system(river water running through the pipes) because it would freeze up. Instead, you should use a closed system with a freeze-proof fluid. In effect, this would use heat from the bottom of the river to thaw the bridge.