GPR is a geophysical method that uses radar pulses to penetrate and map the subsurface of the earth. It uses high-frequency radio waves and transmits a signal into the ground. When the wave hits a buried object the receiving antenna records variations in the reflected return signal. GPR can be used in a variety of media, including rock, soil, ice, pavements and structures. It can detect objects, changes in material, and voids and cracks.

GPR technology can be used to detect the exact location and depth of underground services before new excavations or construction take place, thereby reducing the risk of damaging or cutting the supply of services to other operations.

The depth range of GPR is limited by the electrical conductivity of the ground, the transmitted centre frequency and the radiated power. As conductivity increases, the penetration depth decreases. Typically GPR can be used to detect services up to a maximum of 10 meters.