How do you get out of there in case of fire? If the doors open like that I don't think it would work while inside the tube wouldn't it?
It's a failure of the onboard steam tanks that scares me. ("The steam is stored onboard until reaching the station. Water and steam tanks are changed automatically at each stop")
I don't want to think about what the result of that would look like for the cleanup crew. Eeeewww.
They're just gonna have to send in a crew of astronauts to chisel the freeze-dried human stew off the inside of the tube.
The failure mode for composite overwrap pressure vessels is a slow leak, due to the overwrap containing the metal.
The current design has the passengers in an enclosed capsule in between the compressors and the batteries, with a pressurized air channel running right down the center isle.
Keeping the cabin cool will be a challenge. If that emergency braking is activated, it could get a little warm in there before they are rescued.
I think they may have to quickly repressurize the loop if a car ever gets stuck.
The pressure ratio for the compressors in the CFM56 engines in current model 737-800 models is 32.8:1, so somewhere in the neighborhood of 400-500 psi (will depend a lot on altitude).
Seriously, we've been building machinery to operate safely in this pressure and temperature range for a long time.
Engines do fail on passenger jetliners from time to time. There are numerous stories of planes landing safely after an engine catches fire. But the plane is travelling at a good speed through the atmosphere. How would things be different in a much smaller vehicle sitting stationary in a mild vacuum?
How would passengers escape a battery fire? (as has been seen multiple times on very modern jets)
If the tube had to be repressurized in an emergency, how long would the tube be out of service to be pumped back down again?
Is it worth building a three tube system for such a possibility?