A spectral analysis of ground-penetrating radar data for the assessment of the railway ballast geometric properties

This paper presents a methodology for the assessment of railway ballast using ground-penetrating radar (GPR - 2 GHz horn antenna). The primary approach in this endeavour was the finite-difference time-domain (FDTD) simulations of ballast (a multi-stage process in terms of ballast size). To this effect, a combination of random sequential adsorption (RSA) and FDTD algorithms were applied. The results of the numerical simulation then were used to compare with the experimental investigations results using a container (methacrylate material) of the 1.5 × 1.5 × 0.5 m dimensions. Finally, the modelling of the frequency spectrum peak and the equivalent diameter of the ballast aggregates was developed.