This standard practice provides guidance to the highway engineer in the application of noncontact ground penetrating radar (GPR) to transportation facilities. It is intended to instruct the engineer regarding the specific uses of noncontact radar for pavement layer thickness surveys, quality control of new pavement construction, evaluation of granular base material, identification of zones of asphalt stripping, and assessment of bridge decks. GPR has numerous applications for the transportation industry, but at this time requires extensive training in its use and interpretation of the data output, as well as experience in local pavement conditions.