A comparison between different central frequencies of investigation in buried utility detection through GPR: a study case

Ground Penetrating Radar (GPR) has proved to provide a high reliability in detecting several subsurface features such as water and gas pipes, energy and telecommunication supplies, water reservoirs or air voids. The present work faces a comparison between different central frequencies of investigation to reconstruct the network of utilities located underneath a paved surface and to understand the best strategy of analysis to undertake. To this purpose, a 757 m2 paved parking situated in London was used as test site and divided into three smaller areas. Central frequencies of investigation of 250 MHz, 400 MHz, 500 MHz, 1000 MHz, 2000 MHz, and 4000 MHz were selectively employed over these areas, and the outcomes from the 250 MHz, 500 MHz, and 1000 MHz are here analyzed. The analysis of the data has detected the presence of several utility lines with different placements than those represented within the design charts. Useful insights about the performances of different central frequencies of investigation are here discussed, as well as the usefulness of GPR in validating information collected by visual inspections and available from cartographic maps.