Trenchless Technology Videocast Episode 2 – Victory in Vermont

In this new episode of the “Trenchless Technology Videocast” managing editor Mike Kezdi is joined by Tom Loyer, trenchless technologies market director for Engineers Construction Inc. (ECI), and Joe Lechner, SBU sales manager at Robbins, to discuss ECI’s use of a Robbins SBU-M to complete three tunnels as part of the Early Works Package 3 for the Middlebury Rail and Bridge Project in Middlebury, Vermont.

Vermont’s Middlebury Bridge and Rail Project is no small task — requiring bridge demolition and construction of a new rail tunnel, a new drainage system, and roads for temporary access. And to top it off, construction is being done in the heart of downtown Middlebury, a historic New England college town of 8,700 people.

To compress the project schedule, multiple contract packages are being let out over three years. ECI was subcontracted to bore three drainage tunnels as part of the Early Work Package 3 (EWP3), a contract that included the drainage system. These tunnels, excavated below the downtown historic district in solid rock, were successfully bored under strict line and grade requirements using a motorized small boring machine, known as an SBU-M.

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The Robbins SBU product line ranges from hard rock boring attachments, that work in conjunction with auger boring machines, to self-propelled tunnel boring machines, all of it under 78 in. in diameter. The SBU-M, or Motorized Small Boring Unit, is a motorized, manned-entry rock and mixed ground boring attachment meant to bore in geology such as dry alluvium or rock with UCS of 4,000 psi to over 25,000 psi. It is made for use with any auger boring machine from 48 to 78 in. or any standard pipe jacking unit. The SBU-M uses a hydraulic or electric motor to generate torque while the circular cutterhead, mounted with disc cutters or mixed ground tooling, excavates the ground.

For spoil removal, an invert auger enclosed in steel casing runs beneath the bearing housing and drive motor assemblies. To seal off the cutterhead and protect the motor, a steel bulkhead is added to direct the rock chips into the invert auger.

To learn more about the entire Robbins SBU line, click this link to the Robbins website.