Innogeo made GPR scans of the walls of a cutting in Sarreguemines for Réseau Ferré de France. A 400MHz radar antenna was set up to make a vertical scan of the walls. The measure technicians operated from the ground with no need to go to higher ground. The goal was to detect potential structural anomalies (voids, disorders…) behind facings. Two walls of about 200 m long and up to 8 m high were surveyed.