Bertha tunneling machine

Bertha will soon begin digging below the viaduct its path will replace
Bertha back to drilling after suspension is "conditionally lifted"
Washington governor halts Bertha tunneling after sinkhole forms
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Bertha breaks through repair wall and begins tunneling soil once more (VIDEO)
VIDEO: Bertha, world's largest tunneler, resumes digging below Seattle after 2-year delay
Bertha is nearly ready to start tunneling again (VIDEO)
Big Bertha, world's largest tunnel-boring machine, arrives in Seattle