Accuracy of Ground Penetrating Radar in Pavement Thickness Evaluation – Impact of Interpretation Errors

Ground penetrating radar (GPR) is a nondestructive technique used by road engineers to evaluate the condition and the layer thickness of the pavement structure. The reliability of the method is related to the characterization of the dielectric constant Ɛ of the material, which can be determined from core samples or GPR data. Although numerous research studies report an accuracy of the layer thickness ranging from 3 % to 10 %, the level of confidence of the GPR data is still questioned. This lack of confidence is not only related to the GPR capabilities but is also affected by the interpretation process of the recorded data. In this project, an asphalt pavement was scanned and then analyzed both manually and using a semi-automatic software layer tracking tool. Despite the large amounts of GPR data that are usually collected during road surveys, it is often necessary to interpret the data manually. It was shown in this study that an incorrect layer tracking results in an asphalt thickness error of 19,9 % instead of 3,6 % when using manual interpretation