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00000181-fa79-da89-a38d-fb7f2a000000Bertha, the world's biggest tunneling machine, is a five-story-tall monstrosity of drilling tasked with digging out the tunnel for State Route 99 to replace the Alaskan Way Viaduct. It's journey to the center of the earth underneath downtown Seattle began in July 2013, and since then the project has seen its fair share of successes and failures.Follow the progress of the $3 billion megaproject with KUOW.

No More Tunneling By Bertha Until March 2015

KUOW Photo/John Ryan

State transportation officials say the tunnel machine now stuck beneath the downtown Seattle waterfront won't resume tunneling for another 10 months. Digging is now forecast to resume in March 2015.

Seven weeks ago, Chris Dixon with Seattle Tunnel Partners, the state's contractor, had predicted that his firm would devise a plan to repair the tunnel machine known as Bertha within two weeks. He said Bertha could be repaired and back to work digging the state Route 99 highway tunnel by September 1.

Dixon told reporters on Monday the September estimate was "very optimistic."

"It appears that the repairs are more extensive than we originally thought," he said on Monday. "The main thing we want to do is get the machine in tip-top, 100 percent condition so we don't ever have a repeat of this event."

Seattle Tunnel Partners now expects to complete the tunnel in November 2016, 11 months later than it had promised in its bid for the tunnel job.

[asset-images[{"caption": "Chris Dixon with Seattle Tunnel Partners.", "fid": "30262", "style": "card_280", "uri": "public://201404/DSCN1804.JPG", "attribution": "Credit KUOW Photo/John Ryan"}]]Officials declined to estimate how much the delay and repair work will cost.

Todd Trepanier with WSDOT said no information had surfaced that would suggest taxpayers would be responsible for any costs imposed by the delay and repairs.

Dixon had a different take.

"Who's ultimately responsible and liable for that time and that cost is going to be determined by a review of the contract and negotiating those things within the terms and conditions of the contract," Dixon said.

Getting Bertha back to work would require a sequence of complex engineering and construction tasks:

  • 2 months to drive 75 concrete piles underground to frame a circular shaft 120 feet deep
  • 2 months to dig the 83-foot-diameter shaft
  • 2 months to build a "concrete cradle" that will enable crews to lift the cutter head from the shaft's curved floor to the surface for repairs
  • 3 months for manufacturer Hitachi Zosen to replace Bertha's main bearing and bearing seals

Dixon said he was fairly confident crews could beat the newly announced schedule.
Bertha stalled in December. Its main bearing and the seals that surround it are damaged, with sand and grit contaminating both. Dixon said the root cause of the breakdown is still unknown.

Year started with KUOW: 2009