Seattle Tunnel Partners is making good progress as they continue performing hyperbaric maintenance on Bertha, the SR 99 tunneling machine. Since the maintenance period began on Jan. 5, crews have replaced 250 cutterhead tools (see example below) over the course of 184 hours of hyperbaric shifts. This maintenance is critical as STP prepares for the final 25% of the tunnel drive.The work is taking place in the chamber behind Bertha’s cutterhead, as shown in this image (PDF). As the video below explains, working in this environment is similar to performing an underwater dive.STP will resume tunneling when the maintenance period is complete. The top of Bertha’s cutterhead is located approximately 160 feet below Third Avenue, about halfway between Blanchard and Bell streets. Crews are less than 2,500 feet from the receiving pit near Seattle Center where Bertha will emerge.— more —
During the holiday break, Seattle Tunnel Partners performed routine maintenance and inspections on Bertha, the SR 99 tunneling machine. This included inspection of some of the machine’s cutterhead tools under normal atmospheric pressure. STP decided to begin a hyperbaric maintenance stop this week to inspect the other cutterhead tools on the machine under hyperbaric conditions (this post explains the different types of tools in more detail).Crews plan to spend between one and two weeks inspecting the tools, and replacing them as necessary. However, the duration of the stop could be longer or shorter depending on the number of tools that need to be replaced. STP’s most recent hyperbaric maintenance stop in late October lasted one week.The top of the cutterhead is located approximately 160 feet below Third Avenue, about halfway between Blanchard and Bell streets. Crews are less than 2,500 feet from the receiving pit near Seattle Center where Bertha will emerge at the end of her tunnel drive.Progress updates are posted on Mondays and Thursdays at our Follow Bertha page. You can also follow Bertha on Twitter @BerthaDigsSR99.— more —
Seattle Tunnel Partners crews built their final concrete tunnel ring of the year on Tuesday before stopping for the holidays. The remaining days of 2016 will include a break for crews, followed by scheduled maintenance on Bertha, the SR 99 tunneling the machine.In the year since STP restarted tunneling, Bertha has traveled approximately 5,700 feet and built almost 900 rings. Along the way, crews continued to control the ground as they mined beneath streets and structures, including the Alaskan Way Viaduct.When mining resumes early in the new year, Bertha will be less than 2,500 feet from the pit near Seattle Center where she’ll emerge at the end of her journey. STP will continue to inspect and perform maintenance on the machine as needed.Bertha’s cutterhead is located approximately 160 feet below Third Avenue between Blanchard and Bell streets. Progress updates are posted on Mondays and Thursdays at our Follow Bertha page. You can also follow Bertha on Twitter @BerthaDigsSR99.Happy holidays from the Alaskan Way Viaduct Replacement Program. We’ll see you in 2017.— more —
Frequent observers of the project’s construction cameras may have noticed some white blocks being placed next to the north operations building at the corner of Sixth Avenue North and Harrison Street.
Crews are building a public plaza that will be a centerpiece of the landscaping at the project's future north portal. The reconnection of Harrison, Thomas and John streets will make walking between each side … more