The TBMs at the Follo Line will have a length of about 150 m and weigh 2400 tons. Inside the TBM there are a number of installations, including a conveyor for transport of rocks and the lining of concrete segments.

TBMs excavate rock using cutter disks in the cutter head at the front of the machine. The excavated rock will slide down inside the cutter head on to a conveyor which transports the spoil from the tunnel worksite through an underground conveyor belt. As the cutter head excavates the rock in front of the machine, the rear section of the TBM installs the concrete lining, creating the reinforced tunnel wall.

More about the TBMs.

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