The usual arguments (climate change, increasing fuel prices) are rallied, along with the keeping up with the Joneses, er, Chinese or whatever. The analysis involved pulling a list of big cities in the US and then figuring out pairwise corridors that might be worth high speed or standard speed rail. The idea would be to lay down new track along existing right of way.
The comments thread is really interesting -- it's a mix, but a few of the remarks are _exactly_ what should be considered. Since the author has chosen to take a human-geography approach (where are the people and stuff) instead of a physical geography approach (which route is flattest/cheapest to run), some of the commenters are pointing out egregious physical geography problems with the results. Since the analysis was based on numbers that don't give any indication of journey-to-work, some of the commenters are saying that, hey, a lot of people travel from city A to city B, but it only gets a standard; not so many people travel from city C to city d, and it gets a high speed and suggesting adjustments.
I didn't notice anyone suggesting that this sucker could be built pairwise by a for-profit enterprise, instead of having the guv-mint do it. And yet pair-wise rail funded by private capital (mostly subscriptions raised in the "cities" to be served) is how the whole thing got going in the first place. I do think that the subsidy to roads makes it difficult to build a new (speculative) passenger line, especially in a world in which people _expect_ "public" transit to be heavily subsidized and regulated. But if we were charging user fees on the roads (a real gas tax) and doing cordon/congestion pricing, and we let "public" transit carriers charge enough to actually pay for the service, you might not _have_ to have the government build the thing in the first place.
I ran across this while researching I-Train (also called interstate rail). Some of the serious criticisms of Crawford's proposal seem to revolve around the unwisdom of running high/medium/low speed trains on a single track. I just assumed you'd have to pull more lanes so you could manage that problem.
I hope I don't dream about trains. Or, if I do, that there are sleeping compartments and people in them are having a Really Good Time not sleeping in those sleeping compartments. Doesn't that sound like fun?