High-density dual-polarized GPR array for underground asset mapping

GPR is one of the most reliable instruments to obtain information on subsoil utilities and since its diffusion many efforts have been made in order to reduce the effect of the “human factor” during the data interpretation phase, and to maximize the amount of the surface to be investigated per unit time during data acquisition. Locations where the detection of subsoil utilities is required by public or private organizations may be various in terms of both dimension and logistic. However, a full mapping, even of a small survey area, with a single GPR antenna is often unfeasible, due to the high spatial sampling required; the use of a massive vehicle-towed GPR array may be also not convenient to set up. After many years of technical development, a new system has been recently introduced on the market. This GPR system, thanks to the simultaneous use of an array of 32 channels in different polarization in one compact antenna, enables the collection of a 3-D volume of spatially correlated GPR data. In this paper the effectiveness of a high density array for underground imaging is proven. A dedicated Real-Time Automatic Pipe Detection (APD) algorithm has been also developed, aiming at reducing the “human factor” in radar data interpretation and dramatically decreasing the amount of time needed by data analysis. The implementation, in the same system, of software and hardware features such as the APD, the compact dimension, and the system's maneuverability, results in clear benefit in terms of GPR data density and performance, and high productivity.