So, why not break this down a bit. After all, it's a valid thing to discuss. How many people could you comfortably fit into an RBE circular city system anyway? How much land space would everyone get? A good follow up to that is how much land does someone really NEED? In a suburban setting, you're lucky to get 1/4 an acre in your cookie cutter housing subdivision. So, let's do some fun math and see what we get! :)
Let's make a small city of 5 mile radius yielding 78.5 sq miles of area.
78.5 sq. mi. area = 50,240 acres. (An acre is 43,560 sq ft.)
This is 7.4 times smaller than Houston, TX, which has a population of about 2.3 million shoved in about 600 sq miles. Remember this as we go along here. :)
Set 25% of this area is used for parks and above ground transportation (road, rail, etc): 12,560 acres.
FYI: For NYC, 22% of it's land is for roads (based on a 2006 report I found on land use), and that's a very TIGHT city loaded with roads, so 25% for roads and parks isn't unreasonable for a city that's not designed to be a fuster-cluck of a concrete jungle.
Set 30% for non-residential use (industry, schools, hospitals, etc): 15,072 acres.
Set 45% for residential use: 22,608 acres.
If every acre of residential land was set for a home, you'd have 22,608 homes, and at 3 people per home average, that's a population of 67,824 people. However, that's very impractical and not everyone actually wants a home. If "apartments" were like luxury condo's (and they would be in an RBE anyway), then I definitely would (and I know many others who would) forgo the hassle of maintaining a home and live in a luxury condo.
So, we have 22,608 acres available for residential purposes. Let's set 60% of the that land for homes (each on an acre plot) and the rest for 40-story Condo Complexes, where each complex takes up about 8 acres on average:
60% of land gives us 13,564 acres (rounding down) for homes for 40,692 people.
40% of land gives us 9,044 acres for the Condo Complexes, and at 8 acres a Complex, this gives us 1,130 luxury complexes in the city (rounding down again from 1130.5). Each complex has 1000 units, yielding 1,130,000 units for the city. Each unit averaging 3 people (just like homes) yielding roughly 3,390,000 people.
Now, you might be thinking...1000 units per complex?!
Well, let's put this in perspective, the Venetian Hotel in Las Vegas, which I stayed at in 2001 (thanks to an all expenses paid week long company trip) is one of the most beautiful and luxurious hotels I've ever had the opportunity to stay in. The main hotel footprint is just over 360,000 sq feet, or about 9 acres, and it's 40-stories tall. It hosts just over 4,000 suites, the smallest being 650 sq ft. and the largest being 2,900 sq ft. So, if that place can host over 4,000 suites on a 9 acre plot, then a luxury apartment complex of similar size (8 acre plot) could easily host 1,000 very spacious units for people to live in, if not more, with plenty of space and amenities such that each complex is a small city in and of itself.
So, what do we have in population: 40,692 + 3,390,000 = 3,430,692 people.
So here we have a city that is 7.4 times smaller than Houston, TX, but is actually capable of hosting a population (very comfortably and not cramped at all) that is 1.5 times larger than what Houston has now!
What if I really play with the numbers and go beyond the statistical norms I ran with? When I say statistical norms, I'm referring to 25% of land for parks and roads (not parking lots that are actually part of non-residential land, but roads, highways and railways), 30% for non-residential use, and 45% for residential use. If you look at most cities and towns, that's an average breakdown. And this is all from cities that grew up randomly, haphazardly, with little planning at all from the onset. A RBE city would...obviously...be more precise and streamlined...efficient. But for the sake of argument, let's go nuts!
50240 acres available to use:
40% land for roads and parks: 20,096 acres.
35% for non-residential use: 17,584 acres.
25% for residential use: 12,560 acres.
70/30 split for residential, 70% for homes and 30% for Condos.
Homes: 8,792 acres for that many homes for 26,376 people.
Condos: 3768 acres available. 471 Complexes using 8 acres a complex. 1,000 units a complex, giving us 471,000 units. 3 people per unit giving us 1,413,000 people.
Total population: 1,439,376
So now we have an area 7.4 times smaller than Houston that is capable of comfortably and spaciously hosting 62.5% of the population Houston hosts now. Still ridiculously more efficient and comfortable than current systems.
No matter how you slice it, the RBE city system design can not only handle current global populations, but could easily accommodate even more people, because the city itself is designed for max occupancy while maintaining spacious living conditions at the highest levels of comfort, access and mobility.