The Railway Technical Research Institute (RTRI) developed an on-board ATS-X system to check train speeds in conformity with the amended Ministerial Ordinance on Technical Standards, Article 57 (for the implementation of speed limits depending on railway track conditions) and to strengthen SPAD (signal passed at danger) protection function compared with current ATS systems (ATS-SN and the like). The ATS-X system creates speed-checking patterns for speed limit sections such as curves and stop signal by making the best use of information from ground facilities and an on-board database, in addition to the traditional ATS function, and enables continuous monitoring of train speeds (Fig. 1).

The RTRI laid down specifications for practical systems in cooperation with JR companies, and created prototype apparatus for testing (Fig. 2). The Institute performed field tests in active duty using this apparatus to verify the SPAD protection function, the speed limit function, etc. based on ground coil information and an on-board database. It also conducted safety assessment of the apparatus and confirmed that there were no problems with its practical use. In the ATS-X system, the RTRI made it possible to use the on-board antennas of the current ATS and to utilize existing ATS ground coil cables for new ground coils with the power source to be used for generation/cancellation of speed patterns. Furthermore, the Institute designed the ATS-X ground coils used for transmitting position information to on-board apparatus to be free of power cables, thereby achieving a reduction in setup costs. It was also successful in shifting to the ATS-X system on a step-by-step basis by securing functional compatibility with the current ATS.