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Three Point Construction Completes 1st U.S. Front Steer Microtunneling Project
Running out of ideas, Three Point contacted Icon Tunnel Systems for possible alternative solutions. Due to the hard soil conditions and extremely tight line and grade tolerances required, Icon recommended the front steer microtunneling system from Bohrtec. The front steer system makes it possible for the contractor to excavate the soil while establishing the line and grade instead of displacing it like the pilot tube method. Employing a full cutting face, a pilot tube theodolite guidance system with CCTV monitor, and an illuminated LED target directly behind the cutting head, the operator maintains constant control of line and grade.
As the front steer boring unit is advanced in the ground, the operator can see the position of the cutting head with respect to the intended line and grade at all times and make any necessary corrections to maintain that line and grade. On this particular project, Icon recommended that the 16-inch diameter front steer system be used to establish the exact line and grade and then the contractor would follow with his conventional American Augers Boring Machine to install the required 42-inch diameter steel casing.
Several successful front steer microtunneling projects had already been completed in Europe in varied ground conditions but not yet in the United States. This was a concern of the contractor, but with the proven track record abroad, specifications that met the project’s needs and the backing of Icon, Three Point quickly approved the front steer system for use on this project. According to Boyd, “This was the only system that we believed could deliver the accuracy required for the job in these soil conditions.”
Icon mobilized the required equipment and coordinated with all parties on every step of the delivery, setup and operation. “Because of the critical nature of the project, we flew in Bohrtec’s Lead Operator/Field Engineer for the front steer system, Stefan Janssen, from Germany to provide training and support,” says David Crandall, vice president of Icon Tunnel Systems. “We also had Dan Paster, our national guided auger boring consultant and operator, as well as Rob Langenbach, operations manager and chief operator for Icon on site with Three Point.”
By the time Stefan arrived, the Bohrtec BM400L and front steer system had been delivered and assembled, taking Icon and the Three Point crew only one day.