Condition Assessment of Transportation Infrastructure Using Ground-Penetrating Radar

Abstract

Ground-penetrating radar (GPR) technology has been applied to the evaluation of pavements, bridge decks, abutments, piers, and other constructed facilities to assess as-built conditions and to evaluate damage and deterioration that develops over time. Two basic types of GPR equipment systems are used depending on the type of antenna employed: either ground-coupled antennas or air-coupled horn antennas. Ground-coupled equipment is most suitable for deeper penetrations and for object detection, and where survey speed is not critical. Horn antenna equipment is most suited for driving speed measurements, and where quantitative high resolution results are required. To evaluate the data, two types of data processing are employed: (1) qualitative assessments and manual calculations from graphically displayed data, which is most suited to site-specific evaluations; and (2) automated processing of the raw radar waveforms, which is most suited to production surveys such as pavements and bridge decks. In some applications, such as the measurement of pavement thickness and depth of reinforcement, research studies have verified the GPR findings. In other applications, such as the detection of voids under concrete, the technique can only be reliably used on a site-specific basis, and further development and verification is required before GPR can be considered more generally applicable. New technologies are currently under development that offer the potential to enhance the range of applicability of the GPR technique.