Seattle Tunnel Partners working to repair Bertha
In summer 2013, Bertha, the world’s largest tunneling machine, began digging the SR 99 tunnel beneath downtown Seattle. In December 2013, Seattle Tunnel Partners, the contracting team hired to design and build the tunnel, stopped excavation approximately 1,000 feet into the dig after measuring increased temperatures in the tunneling machine. While investigating the cause of the high temperatures, STP discovered damage to the machine’s seal system and contamination within the main bearing. STP and manufacturer Hitachi Zosen are currently repairing and enhancing the machine.
Bertha back in the access pit
Seattle Tunnel Partners and crane crews from Mammoet have successfully lowered all of the SR 99 tunneling machine's pieces to the bottom of the access pit. Crews are now reconnecting the hundreds of wires and hoses that are integral to the tunneling operation. Below are links that illustrate STP's plan to resume tunneling. The latest schedule is available here.
- Time-lapse video: Three-camera view of crews lowering Bertha's 2,000-ton front end into the access pit (links to YouTube)
- Time-lapse video of repair work on Bertha's front end (links to YouTube)
- Time-lapse video: Bertha's rise revisited (links to YouTube)
- Time-lapse of Bertha’s front end rising to the surface (links to YouTube)
- Time-lapse video of Bertha parking in the pit (links to YouTube)
- Video of Bertha's breakthrough (links to YouTube)
- Video of crews chipping a Bertha-sized circle in the access pit (view on YouTube).
- Narrated video explaining STP's repair plan (view on YouTube)
- Seattle Tunnel Partners repair work plan (pdf 4.8 Mb)
- Time-lapse video of repairs
- Video of crews building the access pit (links to YouTube)
Live view of construction
Construction is hard to see in person because crews built a wall to shield neighbors from construction noise. The best view of STP’s work is from our time-lapse camera. Click on the "SR 99 tunnel access pit" camera in the grid below to watch crews work in and around the access pit, or check out other viaduct-related construction happening elsewhere along the SR 99 corridor.