Railway Substructure Lacuna Detection Using a Forward-Looking SAR GPR

Detection of railway substructure lacunas is an urgent problem for monitoring condition of super ballast layers. In this paper, we describe our work about using a forward-looking ground penetrating radar (FLGPR) to detect the cavity under the railway substructure. Main advantage of FLGPR that is able to look forward by more than several meters includes ability to make detections at greater standoff distances. So trains can run on schedule when a FLGPR is detecting. After processing the data collected and using the synthetic aperture algorithm, we got the distinct radar image of the cavity beneath the substructure 1.2 meters depth