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August 26, 2015

Bertha's drive unit is back in the pit

Photo from WSDOT [enlarge]

Dutch lift company Mammoet has lowered the repaired front end of the tunnel boring machine Bertha into the rescue pit on the Seattle waterfront.

Yesterday Mammoet set the 2,000-ton piece onto a platform at the bottom of the 120-foot-deep pit. The move started on Monday.

The company is now using its massive modular lift tower to get the piece into position.

In the coming days crews will lower and reinstall three arched pieces of metal that are part of the machine's front shield.

Seattle Tunnel Partners and Hitachi Zosen, which built Bertha, will take a few months to connect wires, hoses, cables and pipes.

Repair work outside the pit took about two weeks longer than originally planned, but the target date to resume tunneling is still Nov. 23. A new main bearing, bull gear, cutterhead teeth and a more robust seal system were installed. Crews also welded additional steel to the cutterhead for extra rigidity.

STP is building the tunnel under a $1.35 billion design-build contract. It will take about a year to complete the tunneling.

The tunnel will replace the Alaskan Way Viaduct. It is expected to open in spring 2018, 27 months later than the original schedule.

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