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Measurement, Interpretation and Classification of South African Track Geometry
Published in Kl. Knothe, St.L. Grassie, J.A. Elkins, Interaction of Railway Vehicles with the Track and its Substructure, 2018
Track geometry is generally defined in terms of track gauge, cross level, alignment, and vertical surface profile. The gauge is defined as the horizontal distance between two rails and is measured between the heads of the rails, at right angles to the rails, and in a plane 14mm below the top of the rail head. Cross-level or cant, is the difference between the elevations of the two rails with twist being the rate of change in cross-level. Alignment is the average lateral deviations of the two rails. and the vertical surface profile or top measurement is the average elevation of the two rails.
Allocation of effective maintenance limit for railway track geometry
Published in Structure and Infrastructure Engineering, 2019
Hamid Khajehei, Alireza Ahmadi, Iman Soleimanmeigouni, Arne Nissen
The track geometry describes the position that each rail, or the track centre line, occupies in space (American Railway Engineering and Maintenance-of-Way Association, 2006). The defects and irregularities in the track geometry are mostly used to characterise the quality of the track and to plan track maintenance activities. Track geometry measures can be divided into five classes: (1) longitudinal level, (2) alignment, (3) gauge, (4) cant and (5) twist. Longitudinal level is the track geometry of the track centre line projected onto the longitudinal vertical plane. Alignment is the track geometry of the track centre line projected onto the longitudinal horizontal plane. Gauge is the distance between the inner sides of the rail heads. Cant (cross-level) is the difference in height of the adjacent running tables computed from the angle between the running surface and a horizontal reference plane. Twist is the algebraic difference between two cross-levels taken at a defined distance apart, usually expressed as the gradient between the two points of measurement (EN 13848-1, 2003; American Railway Engineering and Maintenance-of-Way Association, 2006).