Who Picks Up The Tab of HSR?

My response to this GTM article:

I’m sure if GE lobbies the government hard enough it could get the U.S. to adopt HSR. HSR is great, unless the revenues don’t cover the costs. It’s a big risk to take since most HSR projects cost well north of $1 billion.

The only thing I care about is the following: who picks up the tab if high speed rail can’t cover it’s operating costs? If the answer is taxpayers, then this is a no-go. We cannot afford this right now. We can’t have social security, Obamacare, Medicare, an outrageously large imperial-style military, and expensive HSR.