|MadSci Network: Physics|
Yes, it is possible to reduce the rolling friction to close to zero by using magnetic levitation. Some trains have already been built that utilize this concept, but I don't think that any of them are commercially viable yet. The trouble is that the old technology has not stood still, and conventional trains now can routinely go very fast, about 300 km.p.h. (about 190 m.p.h). At speeds above 150 km.p.h.. maglev trains are not that great. The reason for this is that while maglev gets rid of rolling friction it does nothing for the friction stemming from air resistance. They use very streamlined shapes, but then, so can conventional trains. The friction from air resistance starts to become large at high velocities. The only way to get around that is to put the trains in evacuated tubes. This has been proposed, but I think we do not have the technology to do this economically yet. Check out the web sites below and you can see what has been done. By the way, rather than using standard electromagnets, they use a special type of electromagnet using superconducting wire so there are no resistive losses. This entails very low temperatures, about 4 degrees above absolute zero, and that adds complexity and expense to maglev trains. Perhaps some of the new high temperature (still very cold, 77 degrees above absolute zero, which is about 200 degrees below zero on the centigrade scale) superconductors will eventually be able to carry high enough currents that they can be used for this application, reducing cost.
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