March 3 project update: Disassembly begins
Posted on Mar 4 2015 9:01 AM
Bertha reached her stopping point in the SR 99 tunnel access pit on Tuesday night, clearing the way for Seattle Tunnel Partners to begin a disassembly process that will likely take weeks.
Bertha moved forward a total of 57 feet between Feb. 17, when mining resumed, and yesterday. Along the way she built nine permanent concrete tunnel rings, which aren’t visible in the pit because they’re obscured by the ground and the machine’s exterior.
With Bertha now in position, crews have begun the challenging task of taking apart the world’s largest tunneling machine. They will move through a number of methodical steps as they prepare to lift four pieces weighing up to 2,000 tons to the surface for repairs. Among other things, they must disconnect hundreds of hoses and cables, remove motors and weld lift points to the machine’s exterior.
When disassembly is complete, a massive red crane (links to YouTube) will move into position above the pit. Several pieces of the machine will be removed before the cutterhead is lifted out of the pit, as illustrated in STP’s repair video (links to YouTube).
This Wednesday morning photo of Bertha in the pit was taken by our time-lapse camera.
Repair plan resources:
- Video of Bertha's breakthrough (links to YouTube)
- Time-lapse camera view of access pit
- Narrated video (links to YouTube) explains STP’s repair plan in detail
- Time-lapse video (links to YouTube) shows assembly of the massive crane that will lift Bertha to the surface for repairs
- Video of crews chipping (links to YouTube) a Bertha-sized circle on the face of the pit’s southern wall