9üDExtended use of long rails for sharp curves on ballast ladder tracks
  • Development of an advanced buckling analysis program using three-dimensional finite element method to model the structure of arbitrary tracks and to evaluate the nonlinear behavior of tracks and track buckling due to thermal loads
  • Clarification of the remarkable stability against track buckling of continuous welded rails for sharp curves on the ballasted ladder track
  •    The ballast ladder track (Fig. 1) features high stability against track buckling due to the high rigidity of its skeleton and a large lateral ballast resistance(a large lateral resistance of ballast). It is expected, therefore, that long rails should be used more extensively on sharp curve sections, but it is impossible to evaluate the anti-buckling stability of ballast ladder tracks using the existing tools for analyzing track buckling behavior that are primarily designed for cross-sleeper tracks. After creating a detailed three-dimensional finite element model of a ballast ladder track, therefore, the RTRI developed an analysis tool to evaluate the deformation and buckling behavior of tracks due to temperature changes, and applied it to a comparison between cross-sleeper track and ballast ladder track in terms of the behavior of long rails on sharp curves.
       The results showed that the potential buckling danger increased as the curve radius decreased for cross-sleeper track, while no signs of buckling were observed even at a curve radius of 200m for ballast ladder track (Figs. 2 and 3). The comparison also demonstrated that for ballast ladder track, rail displacement in the lateral direction was only about 1mm, even with a temperature change of 40▀C. Based on these findings, the RTRI compiled a manual on the possibility of extensive use of long rails and the conditions for laying them.

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