If you put it above ground, you are a few short bullets from killing everyone in the loop. Hitting a wall of air in a vacuum at hundreds of miles per hour is going to be like hitting a brick wall. Ask any reentering spacecraft.
The same problem exists underground, the weakest points being the stations themselves which can be bombed.
A failure in the system itself (even just a power outage or malfunctioning equipment) would mean people suffocate inside after a matter of minutes.
So, sure, it is possible to create it, but it is impossible to make any sort of safety guarantees. In other words, literally any other mode of transport would be safer, including a hydrogen-filled dirigible.
So, sure, the concept itself might be possible, but an engineer doesn't concern themselves with possible. That is for scientists. An engineer considers what is realistic AND possible, because that is an engineer’s job: to make the possible real. This cannot be real; literally no regulator would ever sign off on it.
Right, because cars and planes and trains and boats and bicycles and footpaths and airships all famously have 100% perfect safety track records, right?
There are no mitigations and the only option is death. Maybe you can repressurize the tubes ... assuming there is power to do so ... to evacuate people. This is the main issue, there is no air outside your vehicle. If a window breaks (see: airplanes where this happens every so often) everyone inside is dead. No discussions, no second chances.
That's the problem. The main problem and you can't engineer around it. There are no emergency procedures because if you have an emergency, you are dead; and there will be emergencies.
Few if any modes of transportation are safe when bombs come into play.
In that case, the air can just "go around" the space craft. Try pushing down a syringe with the end capped. Bet you can't do it. Now imagine that at 700 mph; you will get a lot of heat and destruction. No heat shielding will save you.
> Apply your safety argument to passenger airliners or even ordinary trains and you'll see that they are also "impossible to make safety guarantees" for.
See sibling comment.
