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Transcripción del abstract original del autor: Utility companies employ directional drilling equipment to install substantial portions of their underground piping and cable systems. These rigs support construction of approximately 32,000 km (20,000 miles) of underground lines in the U.S. annually. Directional drilling is now firmly established as the method of choice for installing lines beneath roadways, waterways and other types of improved surfaces. As the use of directional drilling has increased, so has the number of underground strikes produced when either the pilot-hole drill head or back-reaming bit contacts an adjacent line. These strikes result in property damage and, in the worst circumstances, injure utility workers or the public. It is therefore of great benefit to develop sensing technologies which can scan axially in front of, and radially around, the drill head to detect the presence of buried utility lines in close proximity and provide a warning to the rig operator so the boring path can be redirected to avoid contacting these nearby lines. This is the next logical progression in directional guidance and sensing technologies and will significantly reduce the costs associated with utility strikes. This paper reports on the development of two technology platforms – acoustics and electromagnetic -designed to operate with existing directional-drilling equipment to provide realtime detection and estimation of the separation distance (ranging) between the utilities and the drill head. Both technology platforms are developed and currently undergoing testing. It is believed that these technology platforms have a potential for merging. This would assist in detecting both active (e.g., electric lines) and passive (e.g., plastic gas lines) obstacles with the system.