So one of the proposed suspension systems that will be used on the hyperloop include the externally pressurized air cushions. These cushions lift (or at least help lift) the capsule and reduce drag when the capsule is in motion. Also, the tube itself is supposed to have a very low pressure. But won't 100s of capsules moving in the tube releasing significant amounts of compressed air pressurize the tube and thereby significantly increase drag? I suppose this could be solved by perpetually depressurizing the tube, but I did not see any information on it. Does anyone know how this problem was addressed or am I just missing something here?