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30 Conclusions and Recommendations A broad range of potential technological improvements for utility locating and characterization were identified in the SHRP 2 R01 study, Encouraging Innovation in Locating and Characterizing Underground Utilities. These were then evalu- ated with respect to SHRP 2âs expected time and funding con- straints and the programâs desire for short- to mid-term results with minimal duplication of the activities under way at other organizations. One area selected for further research and devel- opment was a solution for locating deep and stacked utilities. Five areas for research and development were selected after a literature search was performed to identify promising geo- physical and tagging solutions for the deep and stacked prob- lem. Prototype development was initiated in all five areas. Development was downselected to two technologies on the basis of bench testing or early field testing. The scanning elec- tromagnetic locator was abandoned after bench trials showed significant technological barriers that could not be overcome within budget and time. The work on internal inertial map- ping systems was halted because this is a proven, if expensive, technology rather than an area of research. The seismic plat- form was put on hold after meeting significant but not thought to be insurmountable problems. The remaining two areas, a long-range RFID tag and an active acoustic locator, were developed to the prototype stage and field-tested. Both technologies need more development to bring them to a commercial-ready state. At this time the RFID tag, suitable for utilities at a 20-ft depth, is the technol- ogy closest to commercial readiness. The remaining issues for the RFID technology are packaging and ergonomics for field use. A finding that was common to both the seismic reflection and the active acoustic technologies is that the propagation of mechanical vibrations in soil is extremely sensitive to cou- pling. This may be the coupling of the signal emitter to the soil or the vibration sensor to the soil. Significant effort will be required to normalize or calibrate the soil-to-device inter- face. This line of inquiry will not be fruitful until the coupling issue can be handled in a repeatable fashion. At present, there is no prospect that an aboveground tool will be developed in the foreseeable future that can simply and quickly locate a majority of deep or stacked buried utili- ties at a site. In truth, there is little likelihood that such a tool could ever be developed because of site geometrics, differing soil conditions, and limitations in power and frequency. C h a p t e r 5
