Safe braking distance is an important consideration in signaling block design for rail rapid transit systems. Historically, block design has developed in accordance with empirically determined stopping distances from various operating speeds plus a safety margin, frequently 35 percent. Because of the impact of poor wheel/rail adhesion and vehicle equipment failures on actual train performance during braking, it became necessary to use a more comprehensive and scientific technique for determining safe braking distance requirements for block design. The safe braking model is an analytic approximation of the performance of automatic train protection equipment, its interaction with passenger vehicle propulsion and braking equipment, and the resulting train performance while decelerating from an initial speed to a stop. The safe braking model considers performance parameters of train control equipment, certain wayside and vehicle characteristics, and performance parameters of vehicle subsystems, and it provides an analytic tool for evaluating the impact of each on safe braking distance. In order to achieve a high level of confidence in the safe braking distance calculations, the safe braking model must be conservative, considering failure modes and worst-case equipment performance parameters which can affect train braking. This paper describes the safe braking model in terms of a train speed-distance profile during braking. The safe braking distance is described in terms of vehicle characteristics and components of the speed-distance profile. Input parameters required to define each component of the safe braking distance are identified, the safety impact of each is discussed, and typical values are presented.

Media Info

  • Features: Figures; References;
  • Pagination: p. 47-53

Subject/Index Terms

Filing Info

  • Accession Number: 00194634
  • Record Type: Publication
  • Source Agency: Institute of Electrical and Electronics Engineers (IEEE)
  • Report/Paper Numbers: IEEE 79CH1454-8 IA Tech Paper
  • Files: TRIS
  • Created Date: Jun 30 1981 12:00AM