Three Point Construction Completes 1st U.S. Front Steer Microtunneling Project

May 2011, Vol. 66 No. 5

Smooth sailing
From the beginning, crews worked seamlessly throughout the entire operation. The system was powered and driven through the ground by one of Bohrtec’s smaller long frame machines, the BM400L, with 100 tons of jacking force and approximately 14,500 foot-pounds of torque. Roughly halfway through the drive, the system encountered two separate locations containing solid quartz rock ranging from six to 8 feet in length each time.

“The front steer went right through the rock,” claimed Boyd. “Typically when you hit rock like that with another boring system, it will completely destroy the head. The front steer was in great shape when it arrived at the receiving pit.”

The front steer exited at the receiving pit/existing manhole within 1/10 of one inch of line and grade, without disrupting or damaging the various utilities and other obstacles that were near the bore path. Production and excavating rates reached an average of 13.5 feet per hour, keeping Three Point ahead of schedule.

“Our operators were able to constantly monitor the exact position of the front steer boring unit using an illuminated LED target, theodolite camera and CCTV monitor. This technology allows the operator to make corrections to the intended line and grade as needed in real time similar to conventional computer-controlled, laser-guided microtunneling with half the headaches and half the equipment,” says Crandall.

Three Point then upsized and completed the bore by following the line and grade established by the front steer with their boring machine pushing 42-inch steel casings with large augers inside.

Three Point was able to successfully finish the casing bore within a matter of two days including setup of the machine. The total project, including the front steer operation, was completed two weeks ahead of schedule and under budget.

Icon Tunnel Systems has steadily grown in technology and expertise to become a full-service company and industry-leader in Pilot Tube Guided Auger Boring and Front Steer Microtunneling for the trenchless construction of pipelines, sewers, and other various underground utilities.

FOR MORE INFORMATION:
Three Point Construction, (301) 884-2755
Icon Tunnel Systems, (800) 836-5011, www.icontunnelsystems.com

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