Big Bertha finally breaks through

With much anticipation, Ber­tha completed the 9,270-foot journey under Seattle on April 4.

Bertha, the 57-foot diameter boring machine, finished the roughly 1.7 mile tunnel earlier in the month, but it took much longer than anticipated.

Bertha started the journey under Seattle in July 2013 to dig the tunnel for the replacement roads, and was originally projected to open Dec. 2015 — though now it is set to finish in early 2019 due to delays with tunneling.

The Washington State Department of Transportation said that in Dec. 2013, Seattle Tunnel Partners had to stop Bertha to repair the seal system that was damaged during digging.

The repair required the transporta­tion department to dig a pit to gain access to the seal. The dig and repair took two years to complete, and Bertha restarted in Dec. 2015.

Due to the delay, Washington State Department of Transportation asked the legislature for an additional $60 million for the 2017-19 budget to con­tinue progress. They also informed the legislature that the costs could reach as high as $149 million, now that tunnel­ing is complete. They also estimate the costs may decrease.

While Seattle Tunnel Partners paid for the repairs in 2015, they are cur­rently seeking reimbursement, claiming a pipe caused the damage to the seal.

According to the Washington State Department of Transportation, it will take four-to-five months to disassemble and remove Bertha. The 8,000 ton ma­chine will sit on a truck for transporta­tion and will be cut into 20 ton pieces, so the disassembled boring machine can be loaded on to trucks by crane.

Despite the completion of Bertha’s digging, the 1.7 mile road still requires much work. The southbound roadway is halfway done, but the Washington State Department of Transportation says the viaduct won’t be ready until early 2019. Any additional funding over $2.8 billion cap for the program would require action by the Legislature.

COURTESY OF WSDOT

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