The ATC system replacing the old ATS-B system for commuter lines was introduced to the Yamanote and Keihin-Tohoku lines of Tokyo area in 1981. The ATS-S system, which was once applied nationwide and contributed to prevent train accidents was found afterwards to be deficient because of the lack of a speed-check function, and was replaced by a newly developed ATS-P system in 1987 or an improved ATS-S.
The number of level crossing accidents increased and peaked at around 1961. Based on the Level Crossing Improvement Promotion Law passed in 1961, the change to grade-separated crossings and the integration of level crossings were pushed forward to decrease the number of level crossings. Since then, the number of level crossing accidents has been declining. However, it is still a big problem, and many countermeasures, such as obstruction-detection devices, are being developed and installed to this day on a continuous basis.
In the meantime, many relay-interlocking devices installed at an earlier stage were reaching the end of their lifetimes, calling for the timely development of a new generation device. The first electronic interlocking device using microprocessors was installed at Higashi Kanagawa station of the Tokaido line in 1985. Relay-interlocking devices are rapidly being replaced by electronic-interlocking devices at present.
