They quote 4 runways and 100+ gates just to handle intra-state travel that would have been on the train? Seriously? Of course, that is is in addition to the umteen thousand lane-miles of highways, also just for those who would have been train riders. Those numbers are, quite frankly, a joke. Maybe NARP believes it, or maybe they just made it up. Sorry, I'm not buying.
While I don't think that I've ever seen, or perhaps just didn't pay attention to just what that $171B brought, I have seen that $171B from several other sources. The number doesn't come from NARP; they're just reporting it.
And keep in mind that this would be spread out over 22 years, building for the future. I can't speak as well to the airline numbers as you can, but I could see it for the roads. They mention 2,300 lane miles. With a distance of 380 miles between LA & San Fran, just adding two more lanes in each direction to the existing highways would account for more than half those miles or about 1,520 lane miles.
Now of course the odds are that more lane miles would be added closer to the big cities and less out in the central valley, but still I could see that 2,300 number being probable.