In concrete applications, ground penetrating radar (GPR) can achieve sub-centimeter accuracy when detecting rebars and post-tension cables embedded in concrete within the first 60 to 80cm. In subsurface applications, GPR can see pipes, trenches, geological layers up to a maximum of 10 meters. These values are estimated and depend on each particular situation and the GPR system used. For example, the higher the water and salt content in a material, the shallower a radar penetrates the ground. Hence GPR can penetrate older, drier concrete better than it does young concrete that is not well cured.