There are dozens of fully-automated train lines, some with attendants but many with absolutely zero personnel onboard, and the number is expected to quadruple w

There are dozens of fully-automated train lines, some with attendants but many with absolutely zero personnel onboard, and the number is expected to quadruple within 10 years. https://en.wikipedia.org/wiki/List_of_automated_urban_metro_subway_systems https://en.wikipedia.org/wiki/List_of_automated_urban_metro_...