I believe this will be possible in the near future
the biggest obstacle is making room temperature super conductors.
I don't see why magnets on the road would be an issue. You just need very weak magnets since you have a superconductor in the car. They can just put the guiding magnets on the sides of the existing roads, or as bridges in the air.
They are using nitrogen to cool a conductor to get a superconductor. Like this it will not go far.
Nitrogen is 70% of air, so there is a lot of it, you take it, cool it and when you use it, it returns to air. But the cooling process of N2 to -200 degrees is very expensive, and can cause a lot of pollution. As any extreme cooling.
But than again they need not let it vaporize like that, they can make better insulation.
But room temperature super conductors are they way to go. But its hard, electrons tend to behave more random if the temperature is increased.
Last edited by missuse; Jan 6, 2012 at 07:04 PM.