Folks once talked about this regarding trains. many said it would never happen - yet many thousands do every day on the DLR.
Indeed the Northern Line and soon the Picadilly Line will be driverless (although a man will still be seen sat there as fought by the ASLEF & RMT Unions.
Those Underground lines are in the process of being resignalled and upgraded from conventional colour light signals to "Moving Bubble" signalling.
ps I work in the rail industry
