Washington State DOT Working to Get SR 99 Tunneling Machine Moving

AASHTO Journal, 14 February 2014

Officials at the Washington State Department of Transportation updated the public this week on its progress in getting the tunneling machine beneath downtown Seattle back to work.

The world’s largest boring machine, which had been tasked with creating the new SR 99 tunnel underneath Seattle as part of the Alaskan Way Viaduct Replacement Program, had been placed in the ground last summer with the hope of opening the new tunnel in late 2015. The machine, also known as Bertha, abruptly halted digging in December. WSDOT recently reported that the seal system protecting the machine’s main bearing was damaged. In order to fix the problem, WSDOT is working with its contractor, Seattle Tunnel Partners, and the machine’s manufacturer to determine the best way to fix the broken seals—either by accessing the back of the machine or by drilling access in front of it.

“STP has not yet fully determined the cause of the seal problems and to date, they have not shown any evidence that suggests the state or taxpayers will be responsible for cost overruns associated with these repairs,” according to a news update posted by WSDOT. “We have requested and expect detailed plans on how the repairs will be made and how STP can recover lost time on the tunneling project.”

WSDOT officials said the process to repair the machine could take months.

A video of WSDOT’s news conference update on Bertha’s progress is available here. Additional information on the entire Alaskan Way Viaduct Replacement Program is available here. Those interested may follow Bertha’s progress through her Twitter account.

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