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Brian Luber

Since railways were established, many systems have been developed to ensure a safe and economic rail service. A signalling system which has played a major role here is that based on the fail-safe principle - instructions on line ahead are passed to the driver via trackside signals.

However, it soon became clear that the best safety equipment is of no use when a driver fails to recognize or wrongly interprets the signal indications. For this reason, different types of transmission equipment, mainly mechanical, were designed to ensure that a train is brought to a standstill after passing a stop signal.

Mechanical transmission equipment has, however, two disadvantages - frequent maintenance and its unsuitability for high train speeds.

Consequently, Siemens developed an inductive system of automatic train control which has three resonant frequencies and which functions without physical contact during transmission. An additional advantage of this system is that no trackside power supply is required for the line equipment.

The first installation employing this principle of operation, known as Indusi, was installed as long ago as 1932 on the Berlin-Hamburg Line. According to the same basic principle, Indusi is still very much in use today, for example on approximately 6,700 vehicles and along 16,000 kilometres of German Federal Railway line.

The demand for additional on-board monitoring as well as for a larger volume of transmission data led to the development of our ZUB 100 automatic train control system. In so doing, the up-to-date technology of microelectronics was utilized and the excellent operating experience gained with the Indusi resonance system applied.