An Evaluation of Fouled Ballast in a Laboratory Model Track Using Ground Penetrating Radar

Abstract

Abstract Ground penetrating radar (GPR) was used to evaluate fouled ballast in a prototype model railway track designed and constructed at the University of Wollongong. To simulate actual conditions, the track consisted of a layer of sub-grade, a capping layer, and a layer of ballast. The track was then divided into seven fouled ballast sections and two clean ballast sections, nine in all. Radar detectable geotextile was embedded under the ballast to highlight the interface between the ballast and capping layer, and then different frequency antennae were used to capture the reflected GPR signals so that the fouled ballast could be evaluated. The design and construction of the model track and the analysis and interpretation of collected GPR data are presented in this paper. Clear patterns of texture observed from the GPR images illustrate the different fouling conditions. The relative dielectric permittivity of each sub-section was also calculated and compared, which proved that it can be used to classify clean and fouled ballast.