CA should've just bitten the bullet and built the whole SF-SJ section underground. It's about 50 miles, about the length of one mid-sized subway line in many part of the world, and it would've simplified the issue of acquiring prime suburban land.
Besides, I just don't see how HSR and Caltrain can share the same railway and avoid major service capacity issues. I think Caltrain is close to capacity as is, and at least a few years ago, major (an hour or more) delays were common.
South Korea built its second branch of HSR reaching Seoul almost entirely underground, with a single 31-mile tunnel [1]. I guess it was faster than trying to acquire land on top of it.
Besides, I just don't see how HSR and Caltrain can share the same railway and avoid major service capacity issues. I think Caltrain is close to capacity as is, and at least a few years ago, major (an hour or more) delays were common.
South Korea built its second branch of HSR reaching Seoul almost entirely underground, with a single 31-mile tunnel [1]. I guess it was faster than trying to acquire land on top of it.
[1] https://en.wikipedia.org/wiki/Yulhyeon_Tunnel