Bertha's Two-Mile Subterranean Journey Is Almost Over
Get an inside look at how the machine is maintained, and how its cutter tools up front are replaced in a subterranean hyperbaric chamber.
Continue Reading http://www.popularmechanics.comGet an inside look at how the machine is maintained, and how its cutter tools up front are replaced in a subterranean hyperbaric chamber.
Continue Reading http://www.popularmechanics.com
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