Here's a good video on one method of calculating what the sum of the smaller individual parts would be. This is for the north east corridor but the same thinking applies to any rail project.

It seems like about a million people live there, not nearly enough individually, and trains would likely alternate at which locations they stop to bring the total travel time between the larger areas down.

Might be hindered by the mountainous terrain though making the cost prohibitive.

"U.S. High Speed Rail: What's Next? Analyzing Extensions and Expansions, and What Makes Sense"

https://youtu.be/zxiGY8p2rCo

Thanks for the link! Will watch later.