The application of track deflection measurements made by video gauge

Abstract

This paper presents direct track deflection data measured using a video gauge (VG) (a digital image correlation (DIC) method) to determine track stiffness characteristics remotely. Two cases are discussed. First, the deflection performance of two novel ballastless trackforms are coupled with an analytical model to assess their stiffness properties for known train loads. Second, the performance of a bridge transition is evaluated under live train passages by the VG; the traffic loads are assumed based on train type to allow track stiffness interpretation from a number of train passes. A track deflection bowl is assessed to show the performance of the transition. The paper initially discusses the DIC technique and the importance and assessment of track stiffness. It then presents the VG deflection data, the global support stiffnesses and deflection bowls. These novel methods are shown to be consistent with other approaches of track stiffness evaluation. The paper concludes with a discussion of how this methodology can be utilised in the railway industry for assessing the trackbed performance of critical zones without the need for track possessions.