Automatic train control with on-board computers

Since 1981, the Automatic Train Control (ATC) devices have been used to maintain a safe distance between trains on the Yamanote and Keihin-Tohoku lines in Tokyo. Although shorter train headways have been desired for years to increase the line capacities, this has been impossible with the conventional ATC. The authors have developed a new ATC system, the Digital ATC system, to replace the conventional ATC. With digital transmission and on-board intelligence, the Digital ATC system enables a reduction in train headways in peak hours at a lower cost than the existing system. In the Digital ATC system, the ground equipment calculates the furthest block to which the train can travel safely (the stopping point) and transmits it to the train as a digital signal. Based on the stopping point information sent from the ground, the on-board equipment retrieves the appropriate permitted speed profile (the braking pattern) from the on-board database. The actual speed and position of the train are compared with the permitted speed profile and brakes are applied automatically when necessary. The new system will be put into use between Minami-Urawa and Tsurumi on the Keihin-Tohoku line in 2003.