Re: Los Angeles to San Francisco route comes in at $6bn
Conceptually, it's one advantage and then a long list of nonsense.
Conceptually it is one advantage and a long list of engineering and logistics problems to address. Funnily enough 85% of them have existing solutions in railway engineering.
1. What happens if it fails? Same as wit a train - it is no different from a heavily loaded train line like the east or west coast mainlines in the UK. Speed differs, but so does breaking
2. 1:1 pairs, maintenance, etc - that is a trivial dual track design with regular interchanges.
And so on...