ATOS

 or is a computerized control system used by the East Japan Railway Company to regulate train traffic on railway lines in metropolitan Tokyo, Japan. It was designed by Hitachi. The first deployment was on the Chūō Main Line in 1997. It is now used on fourteen lines listed below.
On ATOS-enabled lines, each train station has electronic displays, which show scheduled arrival times and train destinations in Japanese and English, warn passengers when trains are arriving or passing through, send updates on system delays and accidents, and display messages to advertise JR products or warn passengers not to smoke. Pre-recorded voice announcements in train stations are also automated by ATOS.
ATOS also directs train drivers through 16-by-16 lamp matrices, which flash messages telling the train driver to speed up, slow down, or adjust their scheduled departure time in order to keep the entire network running on schedule.
Several JR lines in the Kantō region use CTC or PRC systems in lieu of ATOS.