The Ahlers & Cressman blog has been following with great interest the SR 99 viaduct replacement project and the saga of Bertha the Tunnel Boring Machine – whose online profile lists “Sunlight” among her “Dislikes” (more accurately, it is her only listed dislike). Recent articles include Bertha and Brenda: Two Sisters with Different Attributes and Big Bertha Stuck- Differing Site Condition Principles Revisited.
In its latest public project update, WSDOT has published a summary of contractor Seattle Tunnel Partners’ (STP’s) plan and schedule to rescue and repair Bertha, which remains stuck underground near S. Jackson St. and S. Main St. The highlight of the project update is a visual depiction of the rescue mission, along with a step-by-step narrative of plans including “Remove pieces, make repairs.”
WSDOT reports that as of Tuesday, May 13, 2014, STP has started building the underground walls of the circular pit from which workers will pull the 57′ cutter head and other parts to the surface. The cutter head and parts will be hoisted to the surface by what appears (in the repair visual) to be a large gantry crane that will be erected between the Viaduct and Pier 48. Excavation of the pit is currently projected to last through the summer, with disassembly beginning in October.
Fortunately for Bertha, by the time she comes to the surface, Seattle’s fall and winter cloud cover will limit her exposure to distasteful “Sunlight.”