WIT Press

The Radio-based Train Control System ATACS


Free (open access)

Paper DOI






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175 - 183




1,891 kb


N. Miyaguchi, D. Uchiyama, I. Inada, Y. Baba, N. Hiura


In traditional signalling systems, the train location is detected by the track circuit, and the train is controlled by wayside signaling equipment. Therefore, an enormous volume of ground equipment is required for track circuits, signals, level crossings, and so on. The equipment often breaks down because it is installed under unfavourable conditions such as areas prone to extreme temperature fluctuation or excess vibration. And acquisition cost and maintenance cost is high. To solve these problems, we developed and have been introducing a new train control system called “ATACS” (Advanced Train Administration and Communications System). ATACS is a radio-based train control system using information technology.

ATACS is equivalent to ERTMS/ETCS level 3 or CBTC. The ATACS train control method is fundamentally different from traditional signaling systems, because train position detection is determined by on-board equipment rather than by track circuits. Information transmission between the ground and the trains is conducted via digital radio communication, and the signal is displayed in the cab. ATACS is offering full moving block capability. With ATACS, an on-board computer calculates the train location and transmits it to the ground controllers, which continuously transmit Limit of Moving Authority (LMA) to each train based on the reported locations of all the trains on the network. The on-board computer calculates a parabolic braking profile based on the Limit of Moving Authority received from the ground controllers.

We put ATACS into commercial operation on the Senseki Line in October 2011. We have confirmed ATACS’ stability over the last two years, so we are going to introduce ATACS on the Saikyo Line. This will be the first time it is implemented in the Tokyo metropolitan area.

In this paper, we outline ATACS and its operation after the commercial use on the Senseki Line, and plan to implement ATACS on the Saikyo Line.


train control system, radio communications technology, train position detection, track circuit, moving block