The author begins by explaining the indispensable failsafe requirements of a railway signalling system and how they have been develop from the first mechanical interlocking boxes to the semi-conductor electronic equipment now in use. He then describes how the URTL, which is a dual-channel system, achieves almost total positive security by means of: twin switching units operating in antiphase; comparison of the state of the twin switching units; clockpulse checking of the state of the units; basic elements comprising two identical majority logics; control transducers permeable to signals only if a certain Boole algebra chain is established. A functional unit comprises 30 integrated basic elements assembled on a standard logic printed circuit card.

  • Supplemental Notes:
    • Paper read at the IRSE in Brussels on 21/2/75 on the subject of a Siemens electronic logic designated URTL (Uberwachbare Resistor Transistor Logic).
  • Corporate Authors:

    Institution of Railway Signal Engineers

    London,   England 
  • Authors:
    • Lohmann, H J
  • Publication Date: 1975-2-21

Media Info

  • Features: Figures;
  • Pagination: 11 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00126992
  • Record Type: Publication
  • Source Agency: International Railway Documentation, Selection of
  • Files: TRIS
  • Created Date: Nov 18 1975 12:00AM