Bertha's Back!

February 24, 2016



Seattle Tunnel Partners (STP) has been given conditional permission to restart the massive tunnel boring machine, known as Bertha, and resume digging as long as STP adheres to new safety protocols.

Digging on the $3.1 billion underground expressway project under downtown Seattle was shut down January 14 after a large sinkhole opened up at the construction site. It was also reveled at that time that workers had not been given adequate training to run the drill. STP received a 'suspension for cause' from the Washington State Department of Transportation (WSDOT).

As part of the conditions for lifting the suspension for cause, STP will be permitted to tunnel forward and install approximately 25 concrete tunnel rings. During this time, they must demonstrate that they have implemented a number of changes to ensure they can safely continue mining. These changes include:

  • Updated tunnel work and quality plans, including calculations of the amount of soil removed during excavation of each tunnel ring.
  • All necessary training for staff on the tunneling machine is complete.
  • Realignment of key personnel within their quality assurance program.
  • Processes in place to ensure STP’s tunneling work plan is followed.
  • New quality assurance protocols.
  • New personnel at key positions  involved in all tunneling activities.
  • Restructured daily tunneling meetings that include additional participants and protocols.

“Seattle Tunnel Partners has addressed the issues that led to the suspension for cause. This conditional lift of the suspension for cause will give STP an opportunity to demonstrate the effectiveness of their updated mining procedures,” said Acting Transportation Secretary Roger Millar.  “Above all else, this project has always been about safety. We must continue our work to replace the viaduct, but we have an obligation to ensure that work proceeds safely. We will continue to work with STP while taking whatever steps are necessary to protect the interests of the public moving forward.”

Hard as she works, Bertha has been having a tough time throughout the project. In December 2013 Bertha overheated and stalled underneath the city, only 10 percent of the way through the job. That set the project back two years to extract and repair the machine. A barge accident in January delayed work and the project that was originally budgeted at $2 billion with a finish date in 2015 has become a $3.1 billion job with hopes to finish in 2018.

To view how Bertha works, click here.

Source: WSDOT