Tunnel "Trains"

According to record, the United States of America created a machine that could drill through rock by melting it into a round tube.  Although it is a possibility that this was faked to scare the USSR in the Cold War, we have pictures.  If this is real, there is a possibility of "trains" traveling through these tunnels at amazing speeds.  It could allow one to travel across the country... or to a secret base under the rock.  Such a hidden base would almost certainly exist to at least service the "trains."  Such a base, if used to protect against an attack, would almost certainly survive.  If interested, perform reserch.  Add a comment if you find anything more or with others to ponder about something.