Bertha tunnel-boring machine

Year in Review: The Biggest Construction Equipment News Stories of 2016
Bertha pushes past halfway point of tunneling for Washington’s SR 99
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As Bertha visits the dentist, a look at how this machine digs and builds the SR99 tunnel at the same time (VIDEO)
Bertha will soon begin digging below the viaduct its path will replace
No. 6 in 2013: Big Bertha digs in before being stopped in her tracks
Big Bertha, world's largest tunnel-boring machine, arrives in Seattle