@erinanne I also don't want to get into an internet fight. In fact, you are actually the kind of person (having good critical thinking skills) that I'd like to get to know better.

The $37B footbridge point was interesting. But high-speed double track on new stone rail road stone bed ($1,650,000/km, compassinternational.net/…) would be $6.2 billion for 3750 km. So, my napkin-math estimate of 15 billion for the launcher in the paper estimated that it would cost as much per km as about 5 tracks of high-speed rail.