Blackcap Blog

Published at 08:53 on 25 December 2015

That’s the nickname of the giant tunnel-boring machine that’s attempting to excavate a new freeway tunnel under Downtown Seattle.

It had been stuck for two years after being damaged by striking a casing for a test well drilled for the very same project. Yes, that’s how much of a clusterfuck this thing has been. Already.

All these problems, and Bertha is only about 10% of the way home. Given all the above, what are the odds of some other major issue happening? It shouldn’t take a genius to be able to tell this project has major black clouds hanging over it. Moreover, what has already gone wrong pales in comparison to what could go wrong.

Consider another major Bertha breakdown, only this time deep underground beneath a block densly-covered with downtown buildings. There wouldn’t be any way to dig a rescue pit save by purchasing and demolishing some perfectly good buildings, perhaps very large perfectly good buildings. Even if that was done, the rescue pit would have to be so deep that it alone might be an impractical undertaking. Bertha would have to be abandoned in place and the project cancelled.

But it gets worse. The geological strata under Downtown include water-saturated clay and sand beds which are very difficult to tunnel in because they are under pressure and can liquefy when disturbed. Suppose that happens, and subsidence forces most of a downtown block to be hurriedly condemned. There might not even be time for workers to rescue computers, documents and furnishings from the affected buildings. The loss could easily run into the tens of billions of dollars.

Then there’s the matter of the existing viaduct. Excavation of the existing rescue pit has already caused enough subsidence to require a nearby water main to be replaced. The viaduct itself has sank by an amount which was previously decided to be unsafe, then retroactively proclaimed safe simply because they don’t want to close the viaduct before the tunnel opens.

In other words, according to best engineering practices, the viaduct is already unsafe and should have been condemned and closed over a year ago. Given all that, it’s not too hard to see it collapsing. Perhaps a minor to moderate earthquake will strike and do the deed. Or maybe everyone will luck out and there will just be a close call; a viaduct span will partially fail without undergoing a complete collapse and nobody will be killed.

Now, I’m not saying that any of the above will happen, only that there’s a very real chance that it might. In other words, this project is hardly out of the woods yet, not by a long shot.