ATOS is a high density railway transport management system of an unprecedented scale. The system has been continuously built up in stages after the online operation of its first station commenced in 1994 and successfully operating since then. This system, now operating with first and second lines, may be termed the largest of such systems to implement the autonomous decentralization system technology.
or is a computerized control system used by the East Japan Railway Company

East Japan Railway Company

is the largest passenger railway company in the world and one of the seven Japan Railways Group companies. The company name is officially abbreviated as JR East in English, and as in Japanese. The company's headquarters are in Yoyogi, Shibuya, Tokyo....

 to regulate train traffic on railway lines in metropolitan Tokyo

Tokyo

, ; officially , is one of the 47 prefectures of Japan. Tokyo is the capital of Japan, the center of the Greater Tokyo Area, and the largest metropolitan area of Japan. It is the seat of the Japanese government and the Imperial Palace, and the home of the Japanese Imperial Family...

, Japan

Japan

Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

. Hitachi

Hitachi, Ltd.

is a Japanese multinational conglomerate headquartered in Marunouchi 1-chome, Chiyoda, Tokyo, Japan. The company is the parent of the Hitachi Group as part of the larger DKB Group companies...

 designed ATOS. The first deployment was on the Chūō Main Line

Chuo Main Line

The , commonly called the Chūō Line, is one of the major trunk railway lines in Japan. It runs between Tokyo and Nagoya, although it is the slowest direct railway connection between the two cities; the coastal Tōkaidō Main Line is slightly faster, while the Tōkaidō Shinkansen is the fastest rail...

 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. Voice announcements in train stations are also automated by ATOS using speech synthesis.

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

Kanto region

The is a geographical area of Honshu, the largest island of Japan. The region includes the Greater Tokyo Area and encompasses seven prefectures: Gunma, Tochigi, Ibaraki, Saitama, Tokyo, Chiba, and Kanagawa. Within its boundaries, slightly more than 40 percent of the land area is the Kantō Plain....

 use CTC

Centralized traffic control

Centralized traffic control is a form of railway signalling that originated in North America and centralizes train routing decisions that were previously carried out by local signal operators or the train crews themselves. The system consists of a centralized train dispatcher's office that...

 or PRC systems in lieu of ATOS.

ATOS-enabled lines

• Chūō Main Line
  Chuo Main Line
  The , commonly called the Chūō Line, is one of the major trunk railway lines in Japan. It runs between Tokyo and Nagoya, although it is the slowest direct railway connection between the two cities; the coastal Tōkaidō Main Line is slightly faster, while the Tōkaidō Shinkansen is the fastest rail...
  
   in metro Tokyo (Mar. 1997)
• Yamanote Line
  Yamanote Line
  The is commuter rail loop line in Tokyo, Japan, operated by East Japan Railway Company . It is one of Tokyo's busiest and most important lines, connecting most of Tokyo's major stations and urban centres, including the Yūrakuchō/Ginza area, Shibuya, Shinjuku, and Ikebukuro, with all but two of its...
  
   (Aug. 1998)
• Keihin-Tohoku Line
  Keihin-Tohoku Line
  The , is a railway line in Japan which connects the cities of Saitama, Kawaguchi, Tokyo, Kawasaki, and Yokohama. It is part of the East Japan Railway Company network. The line's name is derived from the characters for , and the...
  
   (Aug. 1998)
• Sobu Line (Rapid and Local) west of Chiba
  Chiba, Chiba
  is the capital city of Chiba Prefecture, Japan. It is located approximately 40 km east of the center of Tokyo on Tokyo Bay. Chiba City became a government designated city in 1992. Its population as of 2008 is approximately 960,000....
  
   (June 1999)
• Yokosuka Line
  Yokosuka Line
  The is a railway line in Japan operated by the East Japan Railway Company .The Yokosuka Line connects in Chūō, Tokyo and in Yokosuka, Kanagawa...
  
   north of Kurihama (July 2000)
• Tōkaidō Main Line
  Tokaido Main Line
  The is the busiest trunk line of the Japan Railways Group , connecting Tōkyō and Kōbe stations. It is long, not counting its many freight feeder lines around the major cities...
  
   (Passenger and Freight) (Sep. 2001)
• Joban Line
  Joban Line
  The is a railway line in Japan operated by East Japan Railway Company . It begins at Nippori Station in Taitō, Tokyo and follows the Pacific coasts of Chiba, Ibaraki, and Fukushima Prefectures before the line officially ends at Iwanuma Station in Iwanuma, Miyagi...
  
   (Rapid and Local) (Jan. 2004)
• Tohoku Main Line (Dec. 2004)
• Takasaki Line
  Takasaki Line
  The is a Japanese railway line which runs between Ōmiya Station in Saitama, Saitama Prefecture and Takasaki Station in Takasaki, Gunma Prefecture. It is owned and operated by the East Japan Railway Company ....
  
   (Dec. 2004)
• Saikyo Line
  Saikyo Line
  The is a railway line between Ōsaki Station in Shinagawa, Tokyo, and Ōmiya Station in Saitama Prefecture, Japan. It is a part of the East Japan Railway Company network...
  
   (July 2005)
• Kawagoe Line
  Kawagoe Line
  The is a railway line operated by East Japan Railway Company , which connects the cities of Saitama, Kawagoe, and Hidaka in Saitama Prefecture, Japan...
  
  (July 2005)
• Yamanote Freight Line (July 2005)
• Nambu Line (March 2006)
• Tohoku Freight Line (December 2004)

Further Reading

• JR East Technical Review has several articles about digital train control and ATOS.