Bertha breaks 200-foot mark
Bertha, the SR 99 tunneling machine, has passed the 200-foot mark as she continues her dig toward the north end of downtown Seattle.
By the end of her shift on Oct. 8, Bertha had traveled a total of 209 feet and the top of her cutterhead was about 20 feet below the surface. She averaged nearly 14 feet of digging per day over the past week.
Bertha is still making her way through fill soil that crews have injected with grout to provide additional strength. She’ll pass into untouched glacial soils near South King Street.
Tunneling is expected to continue into fall 2014. The tunnel is on schedule to open to traffic in late 2015.