Autonomous decentralized train control technology

In the conventional automatic train control (ATC) system, the central ATC logic device calculates permitted speed of each blocking section and controls speed of all trains. On the other hand, in the new digital ATC (D-ATC) system, the central logic device calculates each position to which a train can move safely, and sends the information on positions to all trains. On each train, the on-board equipment autonomously calculates an appropriate braking pattern with the information, and controls velocity of the train. These special features realize ideal speed control and also allow high-density train operations. A new architecture for full-scale replacing of the ATC system has been developed. The key points are (1) Two-layer system structure. The line control layer for the entire line consists of autonomous unit zones, and the field control layer has the distributed facilities within each zone. This structure protects service from coming to a complete stop if there is control-system trouble. And also, it provides real-time control performance and ease of system replacement. (2) Fully digitalized track signals. This allows design work to be flexible with no loss of safety. Therefore, all field facilities can be optimized for the system targets. (3) Gap-less track circuits. Lower lifecycle cost is expected with their use. A train can deal with the new and the present ATC as parallel systems. This design permits ATC system change without railway operation stopping. This paper introduces the D-ATC system which has been put to practical use by East Japan Railway Company (JR East).