The people who said this would be a massive boondoggle and voted against the bond in the first place were right all along.
The amount of tunneling/demolition involved is quite viable. lol.
A famous civil engineer, no less than William Mulholland, had his career ended by the geology of those hills.
And you are ignoring the fact they are trying to tunnel through something with very similar geology.
Okay.
Firstly, that merely visually observing the surface of a mountain ("look around when you drove through it") is insufficient to draw meaningful conclusions about the overall geology from an engineering perspective, especially by a non-expert.
Secondly, that even experts have been confounded by the geological features of that particular mountain range.
If you're implying that my referring to an engineering project from approximately a century ago somehow makes it irrelevant, then you'd need to point out some fundamental engineering changes in tunneling and/or demolition (or the study of geology) as they relate to viability thereof, to be an actual argument/refutation.
The disastrous new Bay Bridge project was more representative of modern California infrastructure projects.
The easy way to do this better would be to pick out a firm who had done a good job on a similar project overseas, and tell them to do the same thing under the same rules with the same workers, except over here, and we'll pay a 25% premium to cover relocation expenses. Hell we could pay a 50% premium and still come out way ahead. This would never happen, but it's instructive to think about all of the different levers the system would pull to prevent it.