Tunneling in the US is really expensive but many projects have been done for a billion per mile (China is like $100 million per mile). The Big Dig is the highes

Tunneling in the US is really expensive but many projects have been done for a billion per mile (China is like $100 million per mile). The Big Dig is the highest priced tunnel ever done and not the expected cost of tunneling. If we could do $100 million per mile from San Francisco to Palo Alto (~45 miles), that is $4.5 billion. Charge the $20 each and make ~$1 billion a year. This would be a no brainer. Even at $1 billion a mile and $45 billion total it would almost make sense financially in the current low interest environment. For keeping people sane in the Bay Area, it would definitely be worth it.