I would go one step further and say that the mechanism you describe would also keep the train off the floor (and would possibly be handled by the train, not the

I would go one step further and say that the mechanism you describe would also keep the train off the floor (and would possibly be handled by the train, not the tunnel). It seems to me that using electromagnets for propulsion only and not for levitation would drastically reduce costs. I could only guess at the aerodynamics but I have a feeling you could just give the train a flat bottom and make the end of the train pointed like the intake of a jet engine. At speed it would compress the air and force it between the train and the floor of the tube in a way similar to how an air bearing functions. (Actually all sides, assuming it was rectangular, would work in the same way.)