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Midwest Mole constructing Indianapolis microtunnel

Midwest Mole is constructing a 640 m microtunnel as part of road rehabilitation works in a suburb of Indianapolis, US.

Midwest Mole was enlisted by the Indiana Department of Transportation to build the 640 m long, 84 inch (2,133 mm) diameter microtunnel to improve drainage on the State Road 37 (SR 37) corridor, which will be rehabilitated from 126th to 146th Street to improve safety and traffic congestion.

As part of the overall project, SR 37 will be converted from a surface street to a freeway by constructing tight roundabout interchanges and existing intersections, and depressing the roadway.

Midwest Mole is building the from a pit in a residential area, excavating eastward to SR 37 using an 84 inch microtunnel boring machine (MTBM) supplied by Akkerman Inc.

Due to the length of the tunnel, the company has modified the MTBM, extending the muck conveyor system to accommodate a three-car muck train, as well as equipping the machine with an on-board electric hydraulic power pack to reduce noise in the residential area.

Upon completion of the microtunnel, crews will install 54 inch (1,371 mm) fiberglass pipe from Hobas as the final liner, which will be secured in place with cellular grout.

Midwest Mole Project Engineer Mike Liotti said the geology of the area was a challenge.

“What is interesting about the ground is that there are not connected layers of geology – just pockets of different ground types and groundwater,” he said.

“You can be tunnelling along and then suddenly you’re in a completely different type of ground in as little as 3 m. It’s a very challenging environment for tunnelling.”

Midwest Mole expects to complete the project in late July, with a final completion date of May 2020 for site restoration.

For more information visit the Midwest Mole website.

If you have a project you would like featured in Trenchless International contact Assistant Editor Chloe Jenkins at

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