IMHO the SR 14 backup plan was and is strictly kicking the can down the road for the time being. PB has to wait for Biden to assume power and then the spigot will open for a second base tunnel.

If you look at the part of PBCAHSR which is closer to fruition and set in concrete decision making, ergo the Pacheco crossing, you see they chose the inferior route instead of Altamont and of course the most expensive implementation of that worse route.

If you have gone thru the Moffat Tunnel you know it is a big thing and the proposed Pacheco bore is more than twice that long. It sure looks and smells like a base tunnel.

Shift to SoCal. The SR 14 more surface route has only the advantage of permitting extra commute halts, nice for the real estate exploiters. But it has 2 drawbacks: cheaper and slower. You really think that LaLa and Palmdale are going to stand for San Josie demanding a multi-billion base tunnel and they don't? Especially when the whole thing is pathetically slow in relation to what was promised, clearly a dumbdown. And if they try to up the speeds to say 200mph thru the towns to try to make up time there will hell to pay with the locals about noise and vibration. My surmise is in the end it will be a huge base tunnel going under the Tujunga Wash, etc., etc.

And lastly cheaper is the opposite of what this thing is all about. It is wholly political and patronage is the goal. Base tunnels provide more payola to the cronies whence back to the Party in contributions and other consideration. Think graft.