I think you are a bit off for the average price of this kind of project in developed countries. Let's take France which have a strong history in HSL (thus a lo

I think you are a bit off for the average price of this kind of project in developed countries. Let's take France which have a strong history in HSL (thus a lot of experience, which helps reducing the costs): the new Tours-Bordeaux line (302km) will cost 8B euros, for a line which is "simple" on an engineering point of view (no mountains, no urbanized area) for 6 years of work. Considering the length and difficulty of the HSL in California, you can multiply the cost at least 3 times, so something around $30B. You add the fact that the US labor is more expensive than France (contrary to common knowledge), the fact that it's the first HSL in the US..etc.. and the $64B figure is not too crazy anymore. Your estimate of $2-4B in 4 years is imho absolutely unrealistic.