Road evaluation with ground penetrating radar

This paper provides a status report of the Ground Penetrating Radar (GPR) highway applications based on studies conducted in both Scandinavia and the USA. After several years of research local transportation agencies are now beginning to implement GPR technology for both network and project level surveys. This paper summarizes the principles of operation of both ground-coupled and air-launched GPR systems together with a discussion of both signal processing and data interpretation techniques. In the area of subgrade soil evaluation GPR techniques have been used to nondestructively identify soil type, to estimate the thickness of overburden and to evaluate the compressibility and frost susceptibility of subgrade soil. In road structure surveys, GPR has been used to measure layer thickness, to detect subsurface defects and to evaluate base course quality. In quality control surveys, GPR techniques have been used for thickness measurements, to estimate air void content of asphalt surfaces and to detect mix segregation. Future developments are described where the technique has great potential in assisting pavement engineers with their new pavement designs and in determining the optimal repair strategies for deteriorated roadways. (C) 2000 Elsevier Science B.V. All rights reserved.