What to expect from Bertha as tunneling continues

We’ve been hearing a lot of forecasting lately from members of the public tracking Bertha’s progress. We’ve said this before, but now that Seattle Tunnel Partners crews have passed the 25 percent mark of the tunnel drive, it’s worth repeating: Trying to predict future progress is tempting, but there’s no simple equation for doing so.

Tunneling progress depends on a number of factors, including soil conditions and the need to stop tunneling when Bertha needs repairs or maintenance – something that’s expected to occur over the course of the tunnel drive. STP crews have made consistent progress over the past month, but it’s important to remember that the rate at which tunneling progresses is extremely variable and will differ from day to day.

We have received some suggestions that STP should mine 24/7 – rather than the five, 24-hour days they’re currently putting in each week – in an effort to open the tunnel earlier. Like us, STP wants to open the tunnel as quickly as possible, but there’s a lot more to opening the tunnel than simply boring through the earth.

Stopping for regular maintenance is crucial to ensuring the machine remains functional. STP crews also must build the double-deck roadway within the tunnel and install the various systems – lighting, ventilation, signage, etc. – that must be in place before the tunnel can open. 

Work on these interior structures and systems continues while the machine is mining and will continue for some time after tunnel boring is complete. Because of this, mining more quickly won’t necessarily allow STP to open the tunnel earlier.
Keeping up with Bertha
We recognize that the public has a strong interest in the outcome of the tunnel project, and we are committed to sharing regular progress updates as the project moves forward. Look for twice-weekly updates on our Follow Bertha page.
Along with the latest mining statistics, the Follow Bertha page includes a route map that shows the general location of the machine and some of the characteristics of the “zone” through which crews are currently mining. You can also follow Bertha on Twitter @BerthaDigsSR99.