There are already many driverless subways in existence (especially at airports). Many driven subways (BART in SF) are actually driverless, with a driver there

There are already many driverless subways in existence (especially at airports). Many driven subways (BART in SF) are actually driverless, with a driver there just to close the doors and in case of emergencies. http://en.wikipedia.org/wiki/List_of_driverless_trains#Unattended_Train_Operation_.28UTO_-_completely_driverless.29_systems_and_lines_.28Grade_of_Automation_4.29 http://en.wikipedia.org/wiki/List_of_driverless_trains#Unatt... Good luck implementing totally driverless subways on currently driven subways, though. Unions will totally block the necessary incremental steps, so it would have to be an all-or-nothing back room skunkworks project from a public transit authority.