May 29 project update: New parts for Bertha arrive at Terminal 46

Posted on May 29 2015 2:16 PM

The SR 99 tunneling machine’s new inner seals arrived from Japan as scheduled this week. The pieces, which are integral to Seattle Tunnel Partners’ effort to repair the machine, were offloaded at Terminal 46 and trucked a short distance north to the repair area. The piece shown below is the new inner seal ring, which houses the rubber seals that will protect the new main bearing. Additional photos of crews transporting the piece are available on Flickr.

The SR 99 tunneling machine's inner seal ring

STP and manufacturer Hitachi Zosen chose to redesign the machine’s seal system as part of their repair plan. Manufactured by Hitachi in Japan, the new seal system will be easier to access should the need arise. It will be installed in the coming weeks, along with other essential components designed to equip the machine for the remainder of its journey beneath Seattle. Other important elements of the repair plan include:
  • A new main bearing
  • Enhanced monitoring systems
  • Added steel to strengthen the machine and accommodate the new seal system 
  • Widened openings at the center of the cutterhead
  • Extended arms to mix excavated soil in the chamber behind the cutterhead
Simulation showing additional steel to be installed in the SR 99 tunneling machine.      Crews installing additional steel in the SR 99 tunneling machine
These images show the steel crews are adding to strengthen the tunneling machine.
As owner of the tunneling machine, STP and Hitachi are responsible for all aspects of the repair effort, including the schedule. STP provides an updated schedule  to WSDOT each month, but the state cannot verify the schedule until work to resume tunneling is further along. We will continue to provide updates as we receive them.
Digging into STP’s repair plan
You can continue to track STP’s work on our time-lapse cameras and follow @BerthaDigsSR99 on Twitter for updates. Don't forget to check out the other resources we've created to give you a fuller understanding of Bertha's story: