Part Two: Hypothetical Socio-Political Analysis of Hive Cities
So, the first part of my analysis covered just how large the internal (useable) volume of a Hive City can be. The model I'm using is one the size of the Hive City from the pic I've referenced before, which is 9 miles (14,484 meters) tall. There are, assuming 380 meters (the height of the Empire State Building) in between levels, and assuming level heights remain constant all the way up for simplified construction purposes, 33 levels from the Underhive to the top of the Spire. The shape of the Hive City is a massive Great Pyramid-esque shape to help distribute as much weight as possible across the broadest part of the crust (like ended up done in Egypt, which has some of the thickest bedrock closest to the surface on the planet, so its uniquely suited to titanic pyramids being built there), combined with a super-sized Empire State Building/Chrysler Building-esque super-skyscraper coming out of the top of the Pyramid, going to the top, narrowing into the familiar Hive City pointy needle at the top (which I'm 9/10 sure is meant to be a space elevator anchor according to original specs, just the elevator part broke off a long time ago).
While calculating the internal volume of the Hive City took a (LONG) time to do, I concluded, eventually, that 32,267 Empire State Buildings can fit inside the outer shell of a Hive City of the proposed physical dimensions. I subtracted room for 50 meter thick floors between each level earlier, as well as cutting the number of buildings in half for empty space/breathing room/lack of structures.
I had ended on speculating on population density. I will now quote the Empire State Building wiki:
"According to official fact sheets, the Empire State Building weighs 365,000 short tons (331,122 t) and has an internal volume of 37 million cubic feet (1,000,000 m3).
[51] The interior required 1,172 miles (1,886 km) of elevator cable and 2 million feet (609,600 m) of electrical wires.
[75] It has a total floor area of 2,768,591 sq ft (257,211 m2), and each of the floors in the base cover 2 acres (1 ha).
[76] This gives the building capacity for 20,000 tenants and 15,000 visitors.
[47]"
So, a building with 1,000,000m3 meters of volume can, compensating for needed internal infrastructure, support/maintain up to 35,000 people.
35,000 x 32,267 = 1,129,345,000 people per Hive City.
However, it should be noted at the ESB (not typing that out every bloody time) is not residential, more of an office/business building. And 40K has ludicrously higher pop densities than modern Western offices normally have.
Suitable for 40k, Macao in China apparently has the current world record for population density, at 19,493km2 people per square kilometer (51.3 per square meter). To convert from square to cubic meters, determine the height of the area. Multiply the meters squared by the height.
51.3 x 380m x 33 levels = 643,302 people per cubic meter.
67,114,666,667m3 / 2 (bc of needed empty space/inefficiencies/etc) = 33,557,333,334m3 of usable space
33,557,333,334m3 x 643,302 people per cubic meter = 21,587,499,648,428,870 people that could be fit in a Hive City, assuming Macao-level population density.
We're not done yet. We'll need to cut that number in half to account for space for bulky industrial machines and such, so that's...10,793,749,824,214,430 people.
Okay, that's 10.79+ QUADRILLION people, just for one Hive City.
Okay, but what about rich people wanting their space, because poor people are yucky? They occupy the top... *eyeballs the pic* Let's say 1/5 of the entire Hive City. So they'll need room for their ballrooms, vast parks and gardens, orgy dens to the horizon, and enough gold-plated Versailles duplicates to make King Solomon and Mansa Musa jealous.
10793749824214430 - 2,158,749,964,842,887 (1/5 of total) = 8,634,999,859,371,543 people
Okay, given ALL THAT...we're still dealing with 8.6 quadrillion people in an entire Hive City, fully populated. Which leads us to the next stage of my speculation.
***
Okay, we now have established that the total population of a fully functioning, STC-made, optimal on all thrusters Hive City should be 8,634,999,859,371,543 people. But, as we all know, 40K is far from optimal; the Age of Strife and multiple genocides/massacres/invasions/etc took care of that. So its a tenth of that, maybe even a hundredth of that, that could be living now, or have enough infrastructure to handle it anyways considering how much stuff is broken or in ruins in modern 40K that nobody knows how to fix.
But knowing how many people our theoretical infrastructure could handle, once restored is immensely important. NOW they're living in shitholes eating radiation gruel, but they won't be after our FIXING all the Hive's issues, or trying to via some minimal reforms at least.
Even operating from a mindset that nobles have about "peasants = yucky", you can get more work out of a even moderately well fed, minimally educated work force than you can out of a filthy slime covered illiterate lunatic with guns and knives everywhere on them. Gangers by definition are useless to the Hive City society in question, performing only crimes and contributing no economic profit. They do not aid in defense of the Hive City, they do not grow food, they do not perform any meaningful mechanical or industrial work. They are, quite literally, a waste of space, except they're even worse than that, they represent an active and dangerous threat to those in a Hive City who DO contribute to the economy.
Our PC is all about the numbers, with minimal noble bias aside from "yucky". But by focusing on the numbers, it makes all the sense in the world to spend even 1% more of the Hive City's total GDP to uplift the native population, bc the economic returns are MUCH greater than 1% in exchange. By effectively - via our reforms, STCs, and overall just building basic infrastructure - uplifting the ENTIRETY of the Underhives to becoming just another section of the Lower Hives, you are taking every resident desperately fighting for survival and turning them into a productive member of society. They will have food, water, minimal electrical rations, jobs, and something resembling a future. And that's not factoring in more extreme reforms that could be done in the future once things settle down, like an actual EDUCATION (gasp), which alone would massively balloon every individual's potential far beyond what it is now.
Don't push the poorest of the poor into a corner, and they won't fight like rats when they find themselves trapped. Every rich idiot should be aware of this.
TLDR: Games Workshop doesn't know math from a hole in the ground. What else is new.
***
Oh, and apparently, even fucking air is pumped in from filtration units from the Upper Spire, meaning it gets worse and worse as it goes down, until by the lowest Underhives and the Sump levels its barely breathable filled with toxins and lords know what else. We should build some large air filtration generators for us down here, it will benefit literally everybody down here including us, and vastly improve health conditions in the most passive of ways.