The HP 471-316 TBM was driven by 15 electric motors totaling about 4.7 megawatts of power (6,375 horsepower), built by the Robbins Company of Solon, Ohio, and was the world's largest hard-rock tunnel boring machine as of 2006.
The HP 471-316 TBM was a large hard-rock tunnel boring machine with 15 electric motors and a significant power output (4.7 megawatts) that made it the world's largest of its kind as of 2006.