After the signal acknowledging manipulation by the driver, the existing ATS-Sx (SN, ST, SW and others) loses the function of automatically stopping the train to protect against erroneous operation thereafter. In the wake of the recent train derailment on the Fukuchiyama line, effective measures are also required to prevent excessive speed on curves, but the ATS-Sx system is not able to provide these. To address such issues, the RTRI developed a new ATS system (provisionally called the ATS-X system) providing the existing ATS-Sx system with a new function that transmits digital information between the ground and trains to produce an on-board speed-checking function, thereby significantly enhancing the level of security (Fig. 1). The RTRI performed a field test on the system using prototype components and verified its applicability for real use (Fig. 2). The RTRI has also established an organization to study this system in collaboration with seven JR companies, determined system function specifications common to all these companies in consideration of operability where trains run on the lines of different companies, and summarized the specifications of the items shown below in an explanatory book on the fundamental system.
   [1] Outline of the functions of ATS-X
   [2] Control of the on-board speed-checking function and speed patterns
   [3] Electrical specifications on data transmission between the ground and trains and the format of information content
   [4] Necessary equipment related to the man/machine interface and an outline of their operation
   The RTRI plans to complete a practical system based on these specifications within three years.