9781422284827

Action!

n 2013, there was a monster deep under the city of Seattle—a monster machine, that is. The machine was chewing through the rocks, boulders, and soil 60 to 120 feet (18 to 36 m) beneath the surface. Like a gigantic earthworm, it crunched through 50 feet of rock and soil a day, turning enormous boulders into rubble with ease. Nicknamed “Bertha” after Seattle’s first female mayor, it is the world’s largest tunnel-boring machine, or TBM. It stands five stories tall and is responsible for creating a two-mile (3.2-km) tunnel that will forever change Seattle’s landscape. In December 2013, something went terribly wrong. After crunch- ing through 1,019 feet of rock and dirt, Bertha stopped tunneling.

WORDS TO UNDERSTAND diagnose  identify an illness in a person, or find a problem with something by examining it excavating  digging out

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