Ground penetrating radar: State of the practice for pavement assessment

Ground penetrating radar technology has been used to assess pavement performance and structure for the past 30 years. Nonetheless, after all this time, ground penetrating radar is not currently used on a routine basis by the Departments of Transportation in the US - mainly because of difficulties encountered during ground penetrating radar data interpretation. These difficulties are twofold: ground penetrating radar reflected signals depend largely on the a priori unknown dielectric properties of the pavement materials; and it is usually difficult to accurately locate the individual reflected pulses in the measured ground penetrating radar signals. Furthermore, ground penetrating radar is not an imaging technique such as X-ray; hence, it does not provide an "image" of the subsurface, but rather it presents a set of time domain signals that correspond to the collected scans. This paper presents several processing techniques that can be used to estimate the pavement layer thicknesses and to detect subsurface discontinuities uniquely from ground penetrating radar data.