If the track is enclosed in a smooth symmetric enclosure, either a circle or flat dome, the air within the enclosure will spin along with the train or other tra

If the track is enclosed in a smooth symmetric enclosure, either a circle or flat dome, the air within the enclosure will spin along with the train or other tracked constructions, instead of impeding them. I imagine some texturing on the inside of the enclosure could create small scale surface turbulence that even reduces the minimal friction there.