A ground penetrating radar (GPR) system has been developed and implemented for the U.S. Air Force's pavement evaluation teams. This tool can be used to rapidly, continuously, and non-destructively perform feature delineation, anomaly detection, and layer thickness measurements for airfield pavements. The layer thickness function has been automated. The basic GPR hardware, a Geophysical Survey Systems Inc. (GSSI) SIR-8 with three sets of antennas (500 MHz, 900 MHz, and 2.5 GHz), is mounted in a full-size van and has been extensively modified. An additional SIR-8 controller was installed to allow simultaneous operation of two antenna sets. Direct data capture, on-board digital data storage, and real-time analysis and display capability has been provided by installing a 486 computer and color printer, then connecting them directly to the antenna data lines. Distance markers are also embedded directly into the data stream. Layer thickness measurement is accomplished by combining the dielectric constant obtained from the 2.5 GHz antennas (using the surface reflectivity ratio method), with the 2-way layer travel time measured by the 900 MHz antennas. Automated layer thickness determination techniques have been developed for analyzing data from the ground-coupled antennas that provide the deeper penetration necessary on thick airfield pavements. Automatic data processing software has been developed that performs the direct data capture and calculations necessary to provide real-time output of dielectric constant and layer thickness versus distance travelled. The Air Force GPR device has been successfully used on several airfields to date, demonstrating it can be used to differentiate between pavement features of significantly different thickness, detect anomalies such as voids under pavement and water intrusion, as well as accurately measure the surface layer thickness. Several comparisons of core-measured versus radar-predicted thicknesses have been made, on both PCC and AC, with good correlation.