There is no added cost directly. The original proposition was based upon "free" money: shifting existing dollars from failing and fraudulent expenditures in Afghanistan and elsewhere. The other part of that "cost" is effectively investment in enhancing existing capacity.

I was arguing to make the system not need to be hostile to passenger needs by improvements of the existing infrastructure.

The other point that I failed to emphasize is that I'm working with the primary assumption that getting the necessary right of ways would prohibitively expensive and in some cases close to impossible.