March 27 project update: Final lift approaches
Posted on Mar 27 2015 12:21 PM
Seattle Tunnel Partners is nearly ready to lift the SR 99 tunneling machine’s front end to the surface for repairs. On Thursday, the massive red crane that will make the lift was rolled into place above the tunnel access pit. Crews are now connecting rigging and will spend the weekend making final preparations to lift the 2,000-ton piece to the surface. In addition to the machine’s five-story-tall cutterhead, the section being lifted includes the motors and parts that enable the cutterhead to rotate. It also houses the main bearing and seal system that will be replaced during the repairs.
Because the piece is so large, the lift could take 16 hours or longer, but there is no set schedule. Crews will take as long as necessary to prepare for and safely complete the lift. The crane doing the lifting was built by Mammoet, a firm that has performed similar lifts around the world, including the successful recovery of a Russian nuclear submarine from the bottom of the Barents Sea. Equipped with nearly seven miles of steel cable, the crane bringing Bertha to the surface is capable of lifting more than 2,400 tons. Check out our time-lapse video (links to YouTube) showing the crane’s assembly.
This will be the fourth and final lift in STP’s repair effort, which our narrated video (links to YouTube) explains in detail. To date, crews have removed three pieces of Bertha’s exterior from the pit, the largest weighing 270 tons. The first lift, which occurred on March 19, can be seen from the perspective of the crane operator in this time-lapse video (links to YouTube).
You can track the action on our time-lapse camera and follow @BerthaDigsSR99 on Twitter for updates. We’ll also continue to post photos and videos as STP’s work progresses.
The crane that will lift the tunneling machine's front end to the surface rolled into position on Thursday.