If by agile you mean "exploiting sunk cost fallacy", sure

the real sunk cost would be the opposite approach: spending 60 blns on boring tunnels through mountains that nothing else connect to.

what would be the benefit of tunnel from LA across the mountain range? or a tunnel from SF across the diablo range???

keep in mind these ar elike half of the project cost

this statement has little bearing on how this project is actually playing out, but if it were true - why would we want to manage massive infrastructure projects in the same way bad software projects are managed? via a method regarded by everyone except middle managers with a massive eye roll and a sigh

imagine the opposite situation: boring tunnels costs like 60 blns+.

and taxpayer won't see a penny of the benefit from some tunnel somewhere in mountain ranges that nothing else connects to

ok? my point was that you have projected your notions of project management on to the actions of CAHSR. there was nothing intentional or "agile" about the way the project was executed so far. that caltrain electrification has already been completed (at an exorbitant cost relative to the developed world) is more a consequence of how poorly things are going in the valley than anything

The problem is that it takes a long time to bore tunnels. If anything they should have started that early.