Deep tunneling machines

The Deep Tunnel Boring Machine (TBM)s that is used to dig out tunnels for military DUMBs and to connect them to other military complexes, even miles out. The TBM illustration below can be found in: Design and Construction of Deep Underground Basing Facilities for Strategic Missiles, Vol. 2, Briefings on Systems Concepts and Requirements, Fed. Doc. No. NRC/CETS/TT-82-2.



Two tunnel boring machines (TBMs) sold by The Robbins Company is shown below. The top model was built for La Reunion irrigation project; the bottom one for Boston Outfall. The front ends of these TBMs chew away the rock; the structures that trail behind house the operators and carry away the muck. Photos used with permission from The Robbins Company.