world’s largest tunnel-boring machine

Bertha back to drilling after suspension is "conditionally lifted"
Washington governor halts Bertha tunneling after sinkhole forms
Bertha breaks through repair wall and begins tunneling soil once more (VIDEO)
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VIDEO: Bertha, world's largest tunneler, resumes digging below Seattle after 2-year delay
Bertha is nearly ready to start tunneling again (VIDEO)
Bertha delayed again; won't restart drilling until late December
Board rules WSDOT should have given contractor more warning about pipe struck by Big Bertha before stall
Water main damaged by Big Bertha repair excavation could cost WSDOT $4 million
VIDEO: Big Bertha breaks through: tunnel-boring machine enters repair pit, ready for disassembly