A unique communication and train control system has allowed the German state railway system to decrease train headway markedly and increase train speed on a high density, 100 km stretch of track between Hamburg and Bremen. A similar system has been installed at the Gotthard Tunnel, a major 32 km link between Italy and northern Europe. Operation of this system permits train headways (the time interval between two trains traveling in the same direction on the same route) to go as low as 60 to 90 seconds. The train control system handles three major tasks. First, trains are not allowed to exceed a certain speed limit, depending on their location in the network. Second, the system spaces trains at "the minimum braking distance", the minimum time needed to stop the train (depending on its speed) after it determines that a dangerous situation exists. And third, the system checks whether the switches are set up and locked within the minimum braking distance of a train. A series of computer complexes are located trackside at approximately 25 km intervals, each equipped with three 16-bit minicomputers with 24K words of memory. The next major component is the communication link between computer and train. In these systems, the link is called a "wiggle wire", and it lies on the ties between the tracks, looping around at the end of the line and endlessly crisscrossing itself at specific intervals as it returns down the tracks. The purpose of the wiggle wire is twofold. It is a 36/56 kHz fm digital communications link between the computer and the moving train, and it allows the computers to determine the exact location of the train. These and other chores are handled by on-board microprocessors that count the number of times the wire crisscrosses.

  • Corporate Authors:

    United Technical Publications

    645 Stewart Avenue
    Garden City, NY  United States  11530
  • Authors:
    • Trifari, J
  • Publication Date: 1975-11

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Filing Info

  • Accession Number: 00135191
  • Record Type: Publication
  • Source Agency: Engineering Index
  • Files: TRIS
  • Created Date: Jul 13 1976 12:00AM