The paper describes an audio frequency blockjointless track circuit developed by London Transport and the Westinghouse Brake and Signal Co. Ltd. to meet the special requirements of the LT railway system, which were not fully catered for by the existing audio frequency systems examined when the work began in 1972. The type of track circuit which has been developed in centre-fed, with a maximum frequency around 12 kHz and modulation rates between 7.5 and 12.5 Hz derived through frequency dividers from crystals oscillating in the 1 to 10 MHz range. After describing the circuit in detail the paper deals with aspects of system design when using it; a further section shows how it could be integrated with Automatic Train Operation. It is emphasised that the complex mathematics involved in the design would not have been practical without computer assistance, and much has been learned from comparisons between computer simulation and practical tests. The track circuit which has been evolved is interesting as a compromise between the conflicting parameters set down in the initial studies.

  • Corporate Authors:

    Institution of Railway Signal Engineers

    London,   England 
  • Authors:
    • Norton, D J
    • Lawrence, L S
  • Publication Date: 1975-3

Media Info

  • Pagination: 13 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00125868
  • Record Type: Publication
  • Source Agency: British Railways
  • Files: TRIS
  • Created Date: Nov 5 1975 12:00AM