"Velocity of the projectile is not the same as capacity,"
I think people think this is like a message pod in a vacuum tube in a building, but for humans. That's simply rubbish. This will need lots of pods together. Since they occupy most of the volume in the pipe pumping down the sections in the stations should be fairly quick.
Likewise people seem to think the pods will need gaps, like the gaps between pods. I'd suggest they run as a package and the pods are the train,with each pod tracking the one in front.
More problematical is the cost. Is this a "mass" transit system, given the massive improvement in travel time? That is more doubtful.