The main reason for the change in the height of the ballasted track under the train load is the altered seating of the ties on the ballast. The track transmits vertical forces which cause granular ballast movement and a sagging of the track. Depending on the condition of the line, the calculated mean ballast compression under a 20-tonne axle is between 0.10 and 0.14 N/sq mm. Taking account of all load-increasing influences, the maximum can be up to two to three times the mean value. For permanent-way practice, knowledge of the height-changing effect of various ballast compression values caused by different track and bed forms is of special importance. Laboratory tests have given factors which have an influence on the track-changing effect of various ballast compression forces. Use of these equivalents, which lie between the first and fourth power, show that for the light track form (S 54 rails, sleeper length 260 cm, sleeper spacing 65 cm), we can expect almost three times the height change which results with the present UIC 60-240-60 design, and the latter almost twice that of the UIC 60-B75-60 design. A cost comparison shows that the light construction, in spite of its lower first cost, is the least favorable form owing to its high maintenance costs. A law was developed to determine evaluation figures by means of which various train configurations can be assessed with respect to their track loading. With the application of the fourth-power law for ballast compression and height change, the load values for the selected passenger trains were in part less, and in part up to 67 per cent greater than for the locomotive-hauled Inter-City trains. The track loading produced by the extra-heavy ore-carrying freight train was up to 45 times that caused by the locomotive-hauled Inter-City train.

  • Corporate Authors:

    Hestra Verlag

    Holzhofallee 33, Postfach 4244
    6100 Darmstadt 1,   Germany 
  • Authors:
    • Henn, W
  • Publication Date: 1978-11


  • German

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 00190357
  • Record Type: Publication
  • Source Agency: British Railways
  • Files: TRIS
  • Created Date: May 26 1979 12:00AM