Particle image velocimetry for strain measurement on a railway line

Abstract

Deformation of the railway superstructure can be observed when loads are applied by passing trains. Deflections due to these loads can be measured using various measuring techniques, e.g. linear variable differential transducers (LVDTs), remote video monitoring (RVM) and multi-depth deflectometers (MDDs). Strain gauges are often used to measure the locomotive and wagon wheel loads on the track by calibrating the resulting strains in the bending rail, as measured by strain gauges installed on the flange of the rail. Strain gauges are relatively expensive and specimen preparation is time-consuming and requires some special skills. Figure 1 shows a typical strain gauge setup for wheel load measurement with a calibration frame positioned between two sleepers. Despite the disadvantage of using strain gauges, they are commonly used to determine strains experienced by a rail because of their accuracy.