Train rolling jokes aside, that makes sense... until it doesn't work.

A traffic control system, the thing that makes sure all trains are in known locations, safely spaced, etc.... might be necessarily centralized. There isn't really a "rolling release" you can do for a single system.

Should they have a separate test system for release before "production", sure. Do they? No idea. Is it identical to production? Clearly not. How does the saying go....

> Everybody has a testing environment. Some people are lucky enough enough to have a totally separate environment to run production.