Maglev

No wheels to fail
The SkyTran vehicle "surfs" on a magnetic wave, literally gliding on air as it is driven forward by an electric induction motor. 

No maintenance
Magnetic levitation provides a no contact bearing. There are no wheels to fail & replace, no bearings to grease. The only moving part is the vehicle on the guideway.

Completely safe
In the unlikely event of a power failure to the motor, the vehicle glides to a gentle stop. Unlike other maglev systems, loss of levitation and a sudden collapse onto the guideway is a physical impossibility with the SkyTran design.