Technical Reports

Analytical Descriptions of Track Geometry Variations

  • 01
  • Dec
  • 1983
AUTHOR: Analytical Descriptions of Track Geometry
OFFICE: RPD
REPORT NUMBER: DOT/FRA/ORD-83/03.1
SUBJECT: Track
KEYWORDS: Track Geometry, Track Irregularities, Analytical Descriptions, Track Geometry Models
ABSTRACT: Analyses of recorded track geometry measurements were conducted to develop analytical representations of track geometry variations that exist on the U.S. railroad track. These analytical representations include: 1) continuous stationary random variations described by power spectral density functions with a normalized frequency characteristic and roughness amplitude; 2) randomly modulated periodic effects associated with rail length which are described by joint amplitude statistics and a shape function; 3) isolated events described by a shape function, amplitude and characteristic length. The parameters of these representations are obtained as a function of current FRA track classes for gage, surface, cross-level and alignment. Analyses are also presented to establish the relationships and statistical correlations between the track geometry variables. The effects of curvature and super-elevation on gage, alignment and surface variations are also discussed. The results of the work presented here are expected to be applied to vehicle track interaction simulation studies related to rail car safety, performance and lading damage. A current application being conducted under concurrent efforts is the development of performance based limits on permissible track geometry variations that can be directly related to the railroad operational safety.

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