Test-site operations for the health monitoring of railway ballast using Ground-Penetrating Radar

Effective maintenance of railway infrastructures requires a comprehensive knowledge of the actual condition of the involved construction materials. In this regard, Ground-Penetrating Radar (GPR) stands as a viable alternative to the invasive and time-consuming traditional techniques for railway inspections. This work reports the experimental activities carried out on a test-site area within a railway depot in Rome, Italy. Specifically, a 30 m-long railway stretch was divided into 10 sub-stretches reproducing different various physical and structural conditions of the track-bed. In particular, combinations of varying scenarios of fragmentation and fouling of the ballast were reproduced. The set-up was then investigated using different multi-frequency GPR horn antenna systems. These were towed along the rail sections by means of a dedicated railway cart. Main electromagnetic parameters of railway ballast were estimated for each scenario using time- and frequency-domain signal processing techniques. Interpretation of results has shown viability of the GPR method in detecting signs of decay at the network scale, thereby proving this technique to be worthy for implementation in asset management systems.