The Russians started the same 15 years ago and likely completed it 10 years ago, if the speed at which they expand the Moscow Metro (even in the middle of the Ukraine War) is indicative.
You do know the Moscow Metro doubles as a blast and fallout shelter, don't you?
Civil Defense is pretty important if you're planning on surviving a nuclear war, and urgent if you're planning on starting one!
Don't worry, although unlike the Russians, we don't have a viable Civil Defense program, we do have FEMA!