The disappearing signs of the SR 99 tunnel
It’s been almost a year (April 4) since the tunneling machine Bertha broke through into the disassembly pit near Seattle Center. Today all visible signs of the machine and the large pits that bookended its 1.7-mile journey beneath downtown Seattle are gone.
At the south end, the launch pit is now a smooth plane that will later become the roads and ramps connecting the tunnel to SODO, downtown and the Seattle waterfront:
At the tunnel's north end, the machine’s disassembly pit has been filled up to the surface, and now the final portion of the tunnel's north operations building (the building with the yellow ventilation stacks) is being built above it:
Zooming back and you can clearly see where the closed block of Sixth Avenue North between Harrison Street (in the foreground) and Thomas Street (behind the operations building) will be rebuilt:
Once completed, Sixth Avenue North will provide a north-south connection between Mercer Street and Denny Way, with an on-ramp to SR 99 southbound and the new tunnel. You can follow construction progress on our construction cameras page.