The International Information Center for Structural Engineers

It was April 4, 2017, when the work of tunneling machine Bertha was complete, breaking through into her disassembly pit and marking the end of the 1.75-mile long State Route 99 (SR 99) tunnel beneath Seattle. Now, the Washington State Department of Transportation released a drone video that shows the ongoing construction work from end-to-end inside the tunnel.

Wednesday, 30 July 2014 10:52

UPDATE: Bertha’s Repair Further Delayed

Repairing the tunnel-boring Bertha hit more delays this past week when it was announced the deep access pit that is being built to reach the front side of Bertha would be delayed by a month. Crews need more time to grind and chisel through concrete so the 120-foot deep vault in front of Bertha will be completed in August instead of July as originally planned. Chris Dixon, project director for Seattle Tunnel Partners, believes Bertha will still be fully repaired by March because the repairs had a two-month cushion added to the schedule. While Seattle Tunnel Partners is confident that the machine will be ready to complete the remaining 8,200 feet of tunneling needed for the Alaska Way Viaduct Replacement Tunnel project on time, Washington Department of Transportation is not as optimistic.

Additional Info

  • Date occured Wednesday, 30 July 2014

Seattle Tunnel Partners will begin digging a 120-foot deep pit this week to reach the front side of tunnel boring machine Bertha. The machine is the world’s largest tunneling machine, and it has been stuck underneath Seattle’s downtown waterfront since December 6, 2013. Bertha was built specifically for the Washington State Department of Transportation to work on the $3.1 billion Alaskan Way Viaduct Replacement Tunnel project. The machine completed a little over 1,000 feet of the expected 9,000-foot tunnel before getting stuck.

Additional Info

  • Date occured Monday, 12 May 2014