The early stages of deterioration in asphalt covered concrete bridge decks and pavements is not detectable by the traditional methods such as chain drag or resistivity method. Moreover, they are labourious and less reliable. Core sampling, which gives fair results, causes localized damage to the deck or pavement and hinders traffic. Hence nondestructive techniques such as ground penetrating radar(GPR), which offers rapid and non-contact measurement, are becoming increasingly popular.

This paper describes the recent developments in the application of GPR to highway condition assessment. The discussions include advances in theoretical modeling of radar waveforms, data interpretation techniques and field implementation. The capabilities and limitations of the radar technique for highway application have been highlighted. The application considered in this paper include detection of spacing and depth of reinforcing bars, subsurface cracks and delaminations, and measurements of asphalt thickness and concrete cover.