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March 31, 2015

Bertha's front end slowly emerges

By JOURNAL STAFF

Photo from WSDOT [enlarge]

About 2,000 tons of tunnel boring machine slowly rose from a 120-foot-deep rescue pit between Elliott Bay and the Alaskan Way Viaduct yesterday.

The machine called Bertha has been stuck since December 2013, when it began to overheat and was shut down.

Crews led by Seattle Tunnel Partners have been exacting pieces of the machine so that the defective cutterhead/bearing assembly can be lifted to the surface for extensive repairs.

A giant gantry crane called a modular lift tower is being used to lift the heavy front end. Bertha's front shields were cut into three pieces earlier this month and lifted out with a crawler crane.

“Everything is looking as expected so far,” said STP's Chris Dixon Monday afternoon.

A WSDOT spokeswoman said the specialized lift may even be going a little quicker than anticipated. She said once the cutterhead assembly is out of the hole, it will be rotated a quarter-turn and then set on a repair stand.

STP has said that the lift could take 16 hours or more. Just the quarter-turn rotation is expected to take two hours.

STP hopes repairs will be finished by late May and tunneling will restart in August. STP's latest schedule has the tunnel opening in fall 2017.




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