Bertha enters new zone under 1st Avenue in Seattle

Once a ring is finished, it will stand five stories tall. (WSDOT)

Bertha has entered a new zone in its progress tunneling under Seattle, and is currently very near one of downtown’s most prized cultural attractions.

The world’s largest boring machine has entered zone 5, out of 10 zones. It already passed under the off ramp between Highway 99 and Seneca Street. The machine passed about 90 feet beneath the ramp’s supporting structure. That places it roughly 130 feet below the intersection of 1st Avenue and University Street.

Has the public perception of Bertha and the Seattle tunnel project changed?

Which means that the machine could be underneath the southwestern corner of the Seattle Art Museum — by just a little bit. It is more centered below two apartment buildings at the intersection — one built in 2000 on the western corner of 1st Avenue, and another built in 1996 on the southwestern corner. They have 170, and 305 units respectively.

And on the final corner of the intersection is a mixed-use apartment building built in 1900.

Bertha is aligned with 1st Avenue and is expected to keep following the street before it takes a slight right turn at Stewart Street.

Zone 5 will end at Union Street. Despite there being 10 zones, Bertha is not yet at the halfway point. The zones are different lengths — zones 6-10 are longer than the previous areas that Bertha has passed. The machine is just over one third finished at this point.

Bertha is putting a ring on it

So far, Bertha has traveled 3,558 feet. It has 5,712 to go before the job is done.

That 3,558 feet equates to the installation of 539 rings. In a recent video, the Washington State Transportation Department illustrates how the rings are made, noting that once completed a ring is five stories tall.

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