A network-level road investigation trial using Australian-made traffic-speed 3D ground penetrating radar (GPR) technology

This paper reports on a trial undertaken in 2010 applying a new type of three-dimensional (3D) ground penetrating radar (GPR) technology to measure as-constructed details of existing road pavements at the network level. The technology, a variant of noise-modulated GPR (NM-GPR) developed in Australia since 2006, has many benefits over existing GPR technologies enabling highly detailed investigations of road pavements at highway speeds. Eleven sites totalling around 900 lane-km of road were investigated and analysed in southern Queensland. The sites included a range of road pavement types, including flexible granular and structural asphalt. Data were collected at speeds of up to 100 km/hr, without disruption to traffic and without need for traffic control. Synchronised panoramic photography, road surface photography and GPS measurements were also collected to aid GPR analysis and interpretation. More than 90 per cent of the total length of road scanned produced good quality GPR data exhibiting clear reflections and indicating the suitability of using this equipment for a wide range of pavement types. In the remaining areas the measured reflections were much weaker and less clear, most likely due to increased moisture levels in those areas at the time of investigation. Overall the trial demonstrated that network level GPR data collection and analysis was indeed possible and practical at network level using this equipment, though several improvements to the approach are recommended for future investigations