One of the plans for MX was to have the missile system kept in a large system of tunnels. The missiles would be moved all over the place out west while underground, so the russkies couldn't hit them. Each missile was in a sort of erector/carrier car that had blast doors at each end. I remember that there were breakout tests to see if the erector system could actually erect the missile by breaking it right out of the tunnel.

The idea was to make the missiles largely invulnerable to a Russian first strike, since there was no way to tell where each one was along the system of tracks/tunnels.

Protests over the use of all of the land/money are vaguely in the back of my mind, also. The whole idea never went very far.

That is one of the reasons why the AF had TBM's.