Comment Re: $10 billion (Score 1) 190
$10B divided by 218 miles is approximately $45M per mile. That's not pulling something out of an ass, it's just math.
As for how they came up with that - I would assume very costly studies involving consulting experts in rail, construction, land right-of-way negotiations, transportation permitting, and numerous other expertises involved in the process. The private developer behind this has done rail before, so in theory they know how to price these things out.