Earlier quoted context omitted.
I don't see why you can't compartmentalize it exactly like how I described. A leak in one of the ISS's modules wouldn't take down the whole ISS.
And then what? The train just stops in the middle of nowhere for however many days until the one chamber is fixed?
It would probably be ideal if you could factory make each section and ship it on a standard truck, but with the growth of additive manufacturing, other possibilities also open up, like 3D printing the large metal container onsite.