Technical Reports

Parametric Study of Track Response

  • 01
  • Dec
  • 1977
AUTHOR: Federal Railroad Administration
KEYWORDS: Track Design; Track Degradation; Ballast; Subgrade; Roadbed; Track Response; Concrete Tie; Rail Fastener Stiffness
ABSTRACT: This report was prepared as part of the Improved Track Structures Research Program managed by the Transportation Systems Center. This program is sponsored by the Office of Rail Safety Research, Improved Track Structures Research Division, of the Federal Railroad Administration. The report presents ~esults from a parametric study of track response using a comprehensive track analysis model. Track response parameters include rail and tie bending moments, rail displacement, tie rail seat load, and the distribution of stresses in the ballast and subgrade. The effects of variations in tie sîze, tie spacing, ballast depth and rail fastener stiffness are presented in graphs suitable for track design trade-off studies. Alternative wood and concrete tie track configurations are evaluated using equivalent maintenance criteria. Maintenance criteria for track surface deterioration were reviewed to select ballast and subgrade stress parameters which can be related to track settlement rate for service loads. Formats for cumulative settlement criteria are evaluated using available laboratory data for the behavior of ballast and subgrade materials under repeated loads. Track lateral strength requirements for wood and concrete tie track are also discussed.