DESIGN PHILOSOPHIES IN AUTOMATIC TRAIN CONTROL

Two broad categories of automatic control have emerged in 15 years of rapid transit automation, identified by use of track circuits or separate conductors for the ground-to- train communications channel. Continental Europe has favored a wide-band link which gives flexibility in allocating functions to lineside and on-train equipment, but places heavy reliance on reliability of electronic logic. North American practice, represented by the Washington Metro, is to build up a control hierarchy from elements which can function independently in the event of failure.