When I was a kid I had a similar idea, a low pressure elevated concrete tube transport system. In my idea cars would get rails underneath them and freely enter/exit the tube at some key points. The cars would get a compressor to help keep the not-so-large pressure differential at bay; all inspired by evacuated tube documentaries.

In other words, this has been proposed several times before. However, there are some key innovations here - namely the compressor/nozzle pair and the air suspension system - which may indeed change the game and make this viable.