Digging up streets to bury wires and cables is getting more hazardous and expensive. Beneath most cities lies a maze of gas, electric, telephone, water, and sewer lines that often get broken in the process, disrupting services and threatening workers' lives.
Battelle Memorial Institute in Columbus, Ohio, and Concept Engineering Group Inc. in Pittsburgh have found a safer way: They've designed a trench digger that clears away dirt and rock with supersonic blasts of air. Commissioned by the Electric Power Research Institute, the Soft Trencher blasts ditches up to 6 feet wide and 10 feet deep. Pressurized air jets break up soil into particles that can be sucked up by a high-volume vacuum system. Air is filtered and released, and dirt is carried by conveyor belt to waiting dump trucks. The prototype system can dig faster, with fewer disruptions, than the backhoe it's designed to replace. EPRI is looking for manufacturing partners to market the machine to utilities.