Railway track performance study using a new testing facility

This paper presents results from full-scale laboratory research on railway tracks using the geopavement and railway accelerated fatigue testing (Graft) facility at Heriot-Watt University. A typical ballast depth of 300 mm has been considered, overlying subgrade soil (a typical situation on site). Sub-ballast has not been used, to ensure that only ballast and subgrade behaviour are investigated. The influence of load level and subgrade stiffness for a typical UK track is presented, and from the results a new railway track settlement equation is proposed that fits the measured data in Graft well. The proposed equation can predict track settlement in Graft after a number of cycles for any applied load, and for the clay and subgrade Young's modulus considered in this paper. The threshold stress concept used in fine-grained subgrade materials, granular materials and within railway track design processes has been considered, and a new track parameter (t) within the track settlement equation has been proposed to...

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