Most charming is the financial setup [...] The 2009 tunnel law passed by the City Council specifically says Seattle taxpayers will only pay the $937 million that they have already offered up. But [new] state law says Seattle taxpayers are on the hook for overruns [...] the project gets underway in 2011, scheduled to be done in late 2015.

In July 2013, they bring in Bertha, the largest tunnel-boring machine in the world, built specifically for the project by the Hitachi Zosen Corporation.

[...]  a thousand feet in -- one-tenth of the way through its journey -- it grinds to a halt.

No one knows why. For months. It eventually emerges that the machine itself is broken and no one is quite sure how to fix it, or how long it will take. What broke it? Turns out Bertha ran into a large steel pipe that was left there by a WSDOT [contractor] in
2002 [...]

Funny story: Bertha has no reverse gear. There's no way to back it out [...] as water is pumped out, the surrounding land has started settling, unevenly, cracking streets and threatening nearby buildings and the viaduct itself.