Can cities grow to 50 million inhabitants?

[Azia]

Ithink yes some cities can grow up to 50 million in metro like mumbai Nyc and others bit not before 2050 /2080 ...

some projections by me

1.-) shanghai yangtze delta 100 million by 2090

2.) Bejing tijan 50 million by 2050

3.) La -San diego 50 million by 2070

4.) pearl river area hk 100 million by 2050

5.) boswash agglomeration 100 million by 2060

any others ??

[FREKI]

Originally Posted by Azia

can cities grow up to 50 million people??

Yes of course - with modern transportation systems and distribution there's virtually no limit how how large or how dense an area habited by humans can be...

There will however come a time where distribution and supplying will get very expensive due to the extremely high demand, so sprawling out is not a bad idea for extreme mega cities..

Another downside to mega cities on the 50+ million scale is that property prices will go insane in the center..
Just look at Manhattan and Tokyo today, then imaging both with 3 times the population and an even greater financial position globally..

[mhays]

Yes.

I can't think of why a region like boswash would grow that much. Maybe the Chinese regions because the Chinese population continues to move from rural areas to cities, but that isn't happening in the US.

A city could be a mess at that size, or could work pretty well. Two keys are pretty obvious:
--Focus on efficiency and making things work, even if it means restricting people's choices.
--Put anything that can go underground underground.

I haven't done the math in a while, but it's easy to imagine a city of 80,000,000 in 200 square miles -- a density of 400,000 per square mile. Building it new would make it far simpler.

That would require highrises of course. Things like warehouses that are typically one-story and often one-tenant would go multistory/multitenant as a result of land prices.

Cars wouldn't be possible at that density. If even a few percent of people had them, the whole idea would be unworkable, or at least unlivable.

This city would take the "underground" concept to a new level, allowing the ground level to be about pedestrians, shopping, etc. A concept:

Level -1 would be underground walkways with additional retail. This would reduce the crush of pedestrians at ground level.

Level -2 and -3 would be rail transit.

Level -4 would be deliveries, garbage, construction vehicles, etc. (all no-emissions)

Level -5 would be utilities.

Another part of the concept would be skybridges. Perhaps every building would have a second lobby level at a given height, perhaps 200'. This might just be for pedestrians, or it might even have its own transit system. There might even be a second level in the densest areas, perhaps at 500'. The main benefit would be reducing the reliance on the ground floor lobby and reducing some of the low-level elevator demand, while also providing convenience to occupants by providing conveniences at that level.

[D.D.]

They are always possible.. like freki said a transportation system can make this happen, however I don't know if there can be a citi with so much people as it will be too difficult to control. The will be a metro of such magnitude the sooner or latter, but a city of such magnitude is a hard task.

[liburni]

I think it can, bust as far as functionality goes, cities will look like federations. Cities of that size will be divided into municipalities with maybe one over all mayor.

[ovem]

NO. even if a metropolitan area can be that big, i could never see myself living in such a beast city.

[Epi]

Originally Posted by mhays

I haven't done the math in a while, but it's easy to imagine a city of 80,000,000 in 200 square miles -- a density of 400,000 per square mile. Building it new would make it far simpler.

That would be pretty crazy! Just as a hypothetical game, let's try and work through the numbers.

Let's assume that the city won't be one giant block of built-up building. So you have towers and streets. Streets (even if all pedestrian streets, with room for emergency vehicles and delivery trucks) and setbacks would easily be 25% of all land. Add in some minor greenspace and you'd get maybe 35% taken up by non buildings.

Within buildings itself you probably lose 5% of land for structural support and another 10% to corridors/elevators/stairs and so on.

So you have less (1.00-0.35) * (1.00-0.15) = ~55%

And then you still need space for schools, hospitals, police stations, fire stations, water/sewage treatment plants, power generation facilities, power lines, train stations, major rail lines that you can't build over, airports, public squares, cultural facilities, museums, movie theatres and so on.

All that would easily take up 10% of the total land.

To break that down, 80 million people will probably need 4-5 airports easily, each 2-3 square miles totaling 10-15 square miles or 5% of your total area. Airports also need low zones surrounding them with no tall buildings, which would take much more space as well. For the sake of argument, let's assume airports are well out of the city.

They would need around 300 large sized hospitals (~250,000 people/hospital) which unfortunately need to be separated from other things due to infection control. Each hospital would easily take 100-125 m^2 of space, or roughly 1.5 square miles (~0.75% of your total land area).

You would need roughly 300 universities as well, and even if they were all completely built into skyscrapers, they'd probably at least need one or two prestige buildings, open fields, sports fields or whatever, which would easily take 3-4% of your land.

Area for sports teams (80 million people could easily support 40-50 sports teams) and their arenas which can't so easily be built over as well, would take another 0.5% of your land (150-200m^2 each x20-40 stadiums = 1 square mile)

Assuming you're using all mass transit and limiting cars, you still need roads for emergency vehicles and highways for trucks and other people coming into the city. That's another 1-2% of your land right there for major highways.

And then major train stations would need yet another 2-3% of land even if you use a ton of train line stacking of which I'm not sure how safe it would be.

So that's roughly 10% of your total land.

So now we're at 45% for housing.

For the sake of argument we'll assume that all power generation, water/sewage treatment will take place outside of your city limits. As well, all major power cables will be buried (no large transmission towers).


Now one square mile = 27,878,400 square feet.

45% of that is 12,545,280 square feet.


Each person probably needs at least 250 square feet to live in to be comfortable in a modern city unless you want it to be a slum. This corresponds with say Hong Kong levels of space (some poorer get less space, some richer get more space).

400,000 people x 250 square feet = 100,000,000 square feet.

I'm going to assume approximately 50% of people work (this is approximately how many people have a job in the USA). Each worker needs space, yet again say a rough guess of another 200 square feet (World Trade Center in NYC had ~50,000 workers in 8.6 million square feet of space). Of course not everyone is in an office job, we have retail jobs, doctor's offices, restaurants, wal-marts and so on, all of which significantly raise the amount of space per worker to say 500.

so 100 million + (400,000 * 0.5)(500) = 100,000,000 for a total of 200 million square feet.

200,000,000 / 12,545,280 = 16.

So that means you need a continuous sea of 16 story buildings to house and work everyone in absolutely the most cramped way possible, with no jobs other than service and office. But wait there's more.

Now we come back to the issue of police stations, fire stations, schools, day cares, warehouses, jails, courts, city hall (the voting part which isn't always used not the individual politician offices), TV studios, movie theatres, entertainment complexes (i.e. anything from bowling alleys to dance clubs). Even if all of this could be built into existing buildings, it'll probably raise the building levels either up or down (in subbasments) but either way add more floors to your buildings.

Of course if your city actually wanted any more, like more than a few trees on the side of the road as 'greenspace', actual public squares, actual cultural buildings not built into a skyscraper (like a museum that stands alone for instance) and not have all fire/police/jails built into people's homes and workplaces you'd need a LOT more floors... so let's say the total is now all 30 floor buildings!

So while I think it's completely possible it would be a pretty horrible place to live =)

To put into perspective, the Mong Kok area in Hong Kong at it's worse probably had a density of 400,000 people per square mile. It's less today because people are more spread out and not living 10 to a room anymore. If you've ever been to Hong Kong you'd know it's already ridiculous crowded and most of the city is nowhere that dense. I just can't imagine how much of a crazy place a 80 million person city would be!


Or to put into another perspective, Hong Kong has a built up area of about 110 square miles (or 25% of it's 426sq mile area). Virtually all good land is used in HK as there's lot of islands and mountains. Hong Kong has 7 million people.

So a city of 80 million in 200 square miles, would mean a population density 5-6x that of Hong Kong! Now mind you, even HK doesn't have all supertalls as there's actual some two story buildings around, but that should give you a good idea of the crazyness!

[Occit]

My predictions of agglomerations over 50 mill in 2050: (no particular order)

- Shanghai-Ningbo-Hangzhou-Nanjing-Yancheng
- Guangzhou-Shenzhen-Macao-Hong Kong
- Beijing-Tianjin
- Tokyo-Osaka
- Delhi
- Bombay
- Boston-NYC-Washington
- Manila
- Calcutta
- Dacca
- Jakarta

[ChrisZwolle]

Originally Posted by Epi

That would be pretty crazy! Just as a hypothetical game, let's try and work through the numbers.

Good thinking

[Adam2707]

Nice post Epi.
Although it would be theoretically possible to have a population of 50mil+ in one city.
You've got to think about desirability. At the end of the day you wont get a population that big if people hate living there. They will just move out to somewhere where its less crowded and would be cheaper to live.

Anyway you will need a few self contained cities to get that big, such as a few of these

[mhays]

Epi,

That's interesting analysis and a lot of it makes sense.

However I disagree with some assumptions.

1. Airports. I suspect a couple would do. The flight paths would be outside the 200 sm. Use would be reduced because the city would be able to support fantastic rail service to anything close, supporting "get out of town" travel. Visitors TO any city (vs from) aren't directly related to the population size of a place. Still, air routes could be served by jumbos rather than the commuter routes even NYC gets.

2. Hospitals. Separate hospital highrises can be several times as land-efficient as any hospital is now. Infection control requires separation of systems, spaces, and people, but for most things that can be accommodated vertically just like it's all now accommodated horizontally and vertically. Some units might require more separation but certainly not entire hospitals.

3. Sports would tend to be oriented toward smaller spaces rather than fields, including a lot of rooftop spaces (perhaps their ideal use) as well as indoor spaces. More basketball and ping pong and less baseball.

4. You can assume about 20 sf per person for retail (that's a bit off but close), and 250 for a US office worker, both of which could be a bit lower comfortably.

5. Rather than 16-story buildings, I'm assuming a lot of 50-100-story buildings.

6. Emergency vehicles would use ground level (ambulances could be motorized carts like at football games?) as well as the service level.

7. Major train stations would on the edges of town. Routes going through to other cities would use a circular route around the edge, which would also connect the major stations. From anywhere on the edge there would be great electric tube service into town.

8. Universities and K-12 schools can go vertical as easily as most things can. My city would allow large floor plates, making this easier.

[luci203]

Originally Posted by Azia

Ithink yes some cities can grow up to 50 million in metro like mumbai Nyc and others bit not before 2050 /2080 ...

some projections by me

1.-) shanghai yangtze delta 100 million by 2090

2.) Bejing tijan 50 million by 2050

3.) La -San diego 50 million by 2070

4.) pearl river area hk 100 million by 2050

5.) boswash agglomeration 100 million by 2060

any others ??

Tokyo metropolitan area population 39,188,400 (2008 estimates)

(Population Census of Japan 2000) - Metro 34,607,069.

It could reach 50 million by 2020-2030

[poshbakerloo]

Any city can do, but its only likely to happen is countries like China and India...

[ChrisZwolle]

Originally Posted by luci203

Tokyo metropolitan area population 39,188,400 (2008 estimates)

(Population Census of Japan 2000) - Metro 34,607,069.

It could reach 50 million by 2020-2030

Doesn't Japan have an aging and declining population? I wonder if Greater Tokyo will still get bigger in the future.

[PedroGabriel]

those places must be horrible to live there. there's too much people. anything over 10 million is simple an horrible place. that is if they really have, i often read gross overestimatives here. A region is not really a metro.

I'm sorry for the people who live in such places.

[mhays]

Not in my mind! Tokyo is fantastic. London is fantastic. New York is pretty good overall, and fantastic in the middle. LA has good parts.

[Azia]

i think it is possible that some metros catch up 50 million population

the best canidates are shanghai , mumbai , jakarta , bejing

others are the areas nyc - philly or la - san diego ?? !! the only question is the TIME ..

[Epi]

Originally Posted by mhays

Epi,

That's interesting analysis and a lot of it makes sense.

Hey thanks. But since we're discussing I'm going to reply for the hell of it

1. Airports. I suspect a couple would do. The flight paths would be outside the 200 sm. Use would be reduced because the city would be able to support fantastic rail service to anything close, supporting "get out of town" travel. Visitors TO any city (vs from) aren't directly related to the population size of a place. Still, air routes could be served by jumbos rather than the commuter routes even NYC gets.

I guess it all depends WHERE on Earth your city is, and how 'international' you want your city to be. I assume as a 80 million person city built from scratch supported by the service industry, you'd want a very international an integrated city. This means a lot of international travel (too far for train because of great distance (>1000 miles) or oceans. I picked 3 airports, because such massive cities as Tokyo (which has one of the world's best transport networks) have 2 super airports while NYC has 3 and London has 3. So in fact 3 airports is already a gross misunderestimation of how many you'd need, as there would be 5-6x the amount of people in this city as the catchment are of the NYC airports.

There's a physical limit to how many runways an airport can have safely (due to minimizing mid-air collisions and so on), and how many planes can land on each runway in an hour, and so on. So 2 would definately not be enough and I'd actually say 4 but I just settled on a lowball of 3.

2. Hospitals. Separate hospital highrises can be several times as land-efficient as any hospital is now. Infection control requires separation of systems, spaces, and people, but for most things that can be accommodated vertically just like it's all now accommodated horizontally and vertically. Some units might require more separation but certainly not entire hospitals.

Some things to consider about hospitals. Due to emergency services, hospitals need to be within a close distance of where emergencies happen. Of course when you have such high density, traffic will be a problem, so hospitals need to be very close to people. Having less but more 'mega' hospitals might not solve this problem although it's hard for us to say.

Also, due to the nature of hospitals having a TON of inter-floor traffic compared to your average office building even, it would be hard to run a good hospital that is too tall without running into some problems. Having worked in a 16-floor hospital before, I can tell you logistically it's a challenge even at that height. Still I won't say it's impossible, perhaps your city will have tons of skybridges and maybe every 30 floors, there's a new 'ground floor' of your city

3. Sports would tend to be oriented toward smaller spaces rather than fields, including a lot of rooftop spaces (perhaps their ideal use) as well as indoor spaces. More basketball and ping pong and less baseball.

Well when you start limiting choices, less people will choose to live in your city. I'm assuming that it's not going to be a 3rd world slum but a modern 1st world city, so having lots of choices of sports is important. Even Japan has soccer and baseball stadiums!

4. You can assume about 20 sf per person for retail (that's a bit off but close), and 250 for a US office worker, both of which could be a bit lower comfortably.

Just wondering how you got these numbers. I agree with office, but retail?

5. Rather than 16-story buildings, I'm assuming a lot of 50-100-story buildings.

If you had a lot of 50-100 story buildings, I guess you could theoretically make the city less dense. Still, ground floor would be in perpetual darkness! Also there would be problems with fires and emergency services, especially with densely populated supertall residential towers. It would also up the cost of your city greatly.

This creates a bit of a problem. In order to fit 80 million people into your city, they have to be super cramped in. On the other hand, to build a supertall is super expensive. So it means that everyone would be living in super small, super expensive residences. Are there that many rich people who'd actually want to live in a city with no outdoor sports, crazy density, and so on?

So overall even though this is really a completely theoretical exercise, I wonder if it could actually work in real life. Would enough people actually want to live in a city like that so that the resources to build a place like that be justified?

[anm]

Originally Posted by luci203

Tokyo metropolitan area population 39,188,400 (2008 estimates)

(Population Census of Japan 2000) - Metro 34,607,069.

It could reach 50 million by 2020-2030

the picture shows a dense part of Tokyo, but the metropolitan area (and even Tokyo itself) sure does not look like this everywhere

metropolitan area is not the same thing as a city

[brickellresidence]

dat picture of tokyo reminds me of mexico city´s CBD