December 3, 2018

Curved tunnel extends limits of microtunneling

Curved tunnel extends the limits of microtunneling on a project.

Congratulations to our crew and project partners for extending the limits of microtunneling technology. Michels completed an exceptional 470-foot drive under the Tualatin River in Tualatin, OR in less than a month. The 84-inch diameter tunnel features a vertical U-curve with a 650-foot radius—a North American record for the tightest curve radius at this diameter.

Michels used a new Herrenknecht AVN 1800 machine with double-steering articulation to navigate the radius of the curve and a jacking system to install a specialized reinforced concrete pipe.

The microtunneling drive is part of a design-build project being executed with Mortenson for Clean Water Services.

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