Marty: "Are you telling me that this sucker is nuclear? " Doc: "No, no, no, no. This sucker's electrical. But I need a nuclear reaction to generate the 1.21 gigawatts of electricity I need."

or 3) Achieve zero population growth.

Yes, the first time I saw this a few weeks ago my first thoughts were "there is so much that can go wrong here". I hope it makes it to the surface in one piece.

Serious question from a non-USAian, does that $3.7 Trillion include military hardware (tanks, aircraft, guns etc) and all of the aircraft built for export by companies like Boeing?

I think they mean they are very expensive to build compared to a crossroad and four stop signs. I did a lot of driving in United States last year (8,000 miles) and didn't see a roundabout once. As an Australian, I found this somewhat surprising, as they are very common here. Single lane roundabouts are great, but multi-lane roundabouts give me the willies. In Australia, a standard two-road cross intersection would have priority given to one of the roads, with give way signs (yield) on the minor road. If the priority road has fast traffic, the minor road will have stop signs. In the United States I was surprised to find many intersections with four stop signs facing each other (even in the middle of nowhere). This forces drivers to stop and give way to whomever arrived at the intersection first. Initially this seemed crazy, but after a view days it seemed perfectly natural, safe, and quite polite. My only training prior to this US road trip was 30 years experience driving on the left in Australia. I read the California Road rules booklet five times on the plane and most of it made sense. I would have to say, American drivers seem to be generally more experienced and polite than Australian drivers. I'm sure they will get used to roundabouts.

China is also really huge - same size as the total US and 20% larger than the lower 48. Ignoring where the money to pay for it is coming from, HSR has the potential to be far more convenient than air travel if the termini are in city centers rather than miles away as is required for airports. Geography does set some limits on HSR unless you tunnel trough mountains which is obviously expensive. Imagine getting on a train in LA and arriving in downtown San Francisco in 2 hours. Pity the US is OK with spending hundreds of billions a year on the military but HRS is "expensive".