Nov. 3 project update: Bertha passes the one-mile mark

Posted on Nov 3 2016 11:32 AM
Seattle Tunnel Partners passed the 5,280-foot mark of the SR 99 tunnel on Thursday morning. Less than 4,000 feet now separates the front end of Bertha, the SR 99 tunneling machine, from the receiving pit (links to YouTube) near the Space Needle where Bertha will emerge at the end of tunneling. Bertha’s cutterhead is located more than 200 feet below First Avenue, just north of Stewart Street.
The one-mile point in Bertha’s journey also marks the tunnel route’s departure from the ground beneath First Avenue. While First veers northwest at Stewart Street, Bertha will continue pushing north toward the receiving pit. By passing Stewart Street, Bertha entered Zone 7 of the tunnel drive
How do crews steer the five-story-tall tunneling machine toward the finish line some 4,000 feet to the north? We asked Jerry Roberge, one of Bertha’s operators, that very question. Jerry’s answer, along with exclusive footage from inside the tunnel, can be seen in the video below.