Imaging radar maps underground objects in 3-D

City streets cover a complex array of underground electric, gas, and communication lines. Effective maintenance, expansion, and new installation of these networks require accurate information regarding the location of the conduits, cables, and other structures that lie beneath the surface. Underground maps, if they exist, are often inaccurate, incomplete, or out of date, and attempts to find underground lines or obstacles using metal locators often prove disappointing. To help companies create accurate maps of subsurface networks, researchers have developed a new ground-penetrating imaging radar (GPIR) system that creates sharp, three-dimensional (3-D) images of underground lines and objects. Schlumberger Corporation, in conjunction with the Electric Power Research Institute (EPRI) and the Gas Research Institute, has developed a GPIR system that detects, locates, and produces 3D maps of underground features. The new underground imaging system holds the potential to reduce utility operating and maintenance costs by avoiding unneeded excavation and by reducing incidences of costly damage such as ruptured gas lines. Field demonstrations in New York City, San Diego, and other utility locations have proven the ability of the new mapping system to create accurate images of objects in crowded urban areas at depths as great as 10 ft (3 m).