Skyscrapers, Slums, and the Floor Space Index

Rent control is not the only problem plaguing housing in Mumbai, India. Mumbai also makes it very costly to build skyscrapers. In this video, I discuss the floor space index (FSI), a regulatory tool used around the world to tradeoff plot size and height. Higher FSI lets builders economize on land, reduces sprawl, and increases the value of public transportation. The lessons in urban economics go well beyond Mumbai. Check out the video. It’s one of the best in MRUniversity‘s India series.


Excellent video.

Here's an astounding fact -

Number of buildings taller than 200 meters in ALL of India : 7

Number of buildings taller than 200 meters in NYC alone : 68

Number of buildings taller in DC than 200 meters - 0

Number of buildings higher than 200 meters in all of Virginia - 0 ( )

Number of buildings higher than 200 meters in Baltimore (and one assumes Maryland) - 0 ( )

And for a bonus - number of building higher than 200 meters in Germany - 5, all in Frankfurt ( )

But for the stunted nature of DC, Prof Cowen and Tabarrok could have been writing this blog from the Mall rather than Fairfax.

Germany - is a country of towns. Not cities. Sharp contrast to India, which has low urbanization and has very high proportion of its urban population in a handful of very large cities.

So the need for efficient management of space is far greater in urban India than in Germany

Germany does not have too many cities on the scale of Paris, London, or Rome, that is true (Berlin comes closest).

Number of buildings higher than 200 meters in the UK - 6 ( )

France - 3 ( )

Italy - 3 ( )

Basically, and I did not write this the first time, NYC is a perfect place to build skyscrapers because of the bedrock underlying Manhattan. Of course there are other factors, but even in the U.S., NYC stands out.

Yeah, that makes perfect sense. Only places with firm bedrock can have tall skyscrapers. Oh wait:

Number of buildings taller than 200 meters in sandy Dubai - 70 (


So, here is how they build skyscrapers in Dubai, Doug.

'Creating this city has been no easy task in an environment that is neither hospitable to people nor skyscrapers. In addition to high temperatures, strong winds and a lack of water, piles must be driven through 130 meters of sand to reach the bedrock essential to support such huge buildings. Despite these challenges, the city is home to 17 of the world’s 100 tallest skyscrapers.'

The don't build them on sand, they are supported by bedrock.

Maybe you should spend a bit of time reading instead of using the latest Internet jargon when displaying ignorance.

Shouldn't we also take fire-fighting capabilities also into account when making such a comparison ? ( Also infrastructure that Kris points to below).

at Anonymous, yes, good observation. I was going to say that I would not trust a skyscraper built in India anymore than I trust them in the Philippines, as the standards for construction are suspect. Most soil in the Philippines settles, and I notice microcracks all the time in new buildings made of concrete. I would not trust Dubai skyscrapers that much either, unless they use foreign engineers, which given that they have lots of money but little local talent, they probably do.

I raised this question in an earlier thread but didn't get a satisfactory response, so I'll repeat it here.

If people have to live in really tall buildings, electricity (which drives elevators) becomes a necessity, not a luxury. In much shorter buildings in many parts of the country, getting trapped in elevators during power cuts is a frequent occurrence. Doesn't that problem have to be solved before we can go about building taller buildings?

There's other infrastructure that has to be taken care of too: water, sewage, garbage.....

Sure. But these are problems that are case-specific.

There are some builders who can indeed build tall buildings and also ensure the elevators work all the time, electricity is never down, among other things. Today even those builders are prevented from building tall buildings.

The market will price in the problems that you are talking about.

I think this is an entirely valid point. Infrastructure and real estate development have to move together. Thus, the assumptions about the viability of certain types of construction may prove untrue in given circumstances. This is really the foreign aid dilemma. Viewed from DC, higher houses make sense. Viewed from Mumbai, the constraints might be more primitive and yet more binding than you would think.

I love Paris every moment
Every moment of the year
I love Paris
Why oh why do I love Paris

Partly because Paris hasn't allowed the construction of buildings higher than 121 feet, a limitation adopted in 1977 in response to the Tour Montparnasse. The height limit was modified in 2010 to allow apartment buildings as tall as 150 feet and office buildings up to 590 feet. The new height limitation was aimed at the 13th, 15th, and 17th arrondissements, but skyscrapers are coming to Paris. When the modified height restriction was adopted, only 2 million of the Paris metro area's nearly 12 million residents lived within the city's limits, undoubtedly because the previously strict height limits on buildings kept the number of city dwellers low. Paris chose urban sprawl as preferable to upsetting the skyline that makes Paris Paris: "Paris’s 19th century Hausmann-style architecture, which traditionally features five-story buildings with 45-degree angled roofs (to allow for sunlight to reach the streets), wrought ironwork and decorative stone facades, is world-renowned and sets Paris apart from other large cities. Andrew Ayers, an architectural historian who has written about Paris’s architecture, believes “the beauty and richness of a city like Paris comes from the combined effect of lots of very small-scale buildings acting together.” They allow for a clear sight line to the Eiffel Tower and complement other monuments that define Paris architecturally, like Notre Dame and the Arc de Triomphe. Conversely, tall modern towers—like the Tour Triangle’s large, glass-fronted triangular plan—as Ayers puts it “interact with nothing but themselves.”

Only two million because it's a tiny area, not because of a lack of density. Paris is a great example of how a city can have high density neighborhoods without high rises.

The mansard roof might allow more sunlight but I believe its origins stemmed from tax avoidance. Building taxes were to the "crown line"/roof line. By designing the mansard roof they were able to add additional floors without being taxed.

if a city gets rid of property zoning, then it can let rent control lapse.

Property zoning is the great non-PC issue, and not just in India, but the West Coast of the US and Boston and elsewhere. No one believes in free markets in property development in their own neighborhood.

Which makes all the pompous pettifogging about "rent control" perfectly pathetic.

We believe in free markets (as carefully defined and circumscribed by us)!

Offhand, it seems that "highly regulated space" and "space where it makes sense to build a skyscraper" are pretty much the same space. No doubt someone can think of a notable skyscraper in a lightly regulated space, but it seems a bit odd to complain that regulations stifle skyscrapers if the bulk of skyscrapers were built in highly regulated spaces.

Alex, I think was has to be careful about the notion that increasing the supply of housing with higher FSIs will not bring more congestion.

If governments hold restrictive policies in place for many years, repressed demand can be much greater than supply. Thus, building taller buildings might have the effect of drawing people living on the periphery into the center of town, such that congestion is in fact increased.

This is similar to, for example, I-95 north of New York, which has three lanes of takeaway capacity versus, say, six for Baltimore, a city a quarter the size. If the capacity of I-95 were doubled -- and it should be -- the daily congestion might actually not improve as much as one might hope, because those discouraged from driving earlier now come on to the highway.

Put another way, if you are short of capacity by 100% and add 50%, then you will still be short of capacity by 50%. That is a damning indictment of governance of either Connecticut or India, but the assumption that increasing capacity brings you all the way back to a market clearing equilibrium may be untrue. You're still swimming under water, just closer to the surface.

If people have to travel less distance, that cuts congestion. Even if there's more localized congestion in a particular neighborhood, transportation efficiency might have gone up overall. Despite all the geographic barriers in NYC, you have far more jobs and people there within a half hour travel time from each other than in less dense USA metro areas.

On a side note, Congestion can be a red herring at times. People bring up the induced demand problem with building roads in an irrelevant way. The goal of roads is not to have minimal congestion but to have as much capacity able to travel in a short amount of time as possible. If a road is just as congested after doubling capacity that's still a big success because the point is that twice as many people are able to use it effectively. This fallacy is often made by transit loving, car hating urbanists. Take their logic to the extreme and we should just ban autos so there won't be any more congestion.

"...transportation efficiency might have gone up overall"

Sure, that's true. And it's great for the person who moved from the periphery to the core. But the guy who already lived in the core and now has to wait longer at the grocery store may not quite see it that way.

Agree about the congestion red herring, but I think it's important to note -- and I did this for Alex' sake -- that adding capacity is not the same as resolving a structural shortage.

Is Mumbai still a sh*thole with romantic decaying Gothic buildings? I haven't been there for years. This isn't language I would have used in the olden days but now it's presidential it does help get to the point.

That describes a lot of places in the world, including many places in downtown Athens where people have left, and abandoned buildings remain. Poverty is photogenic. Actually describes parts of the US Midwest as well.

I'm amazed at the academic nature of the video, and that the local "experts" didn't raise this: there is little infrastructure to add more vertical space. The roads, water, schools, etc just can't support say a doubling of the vertical space in most parts of downtown Bombay (I live there). Where FSI has been added, traffic has become ridiculously bad. As one of the earlier posters said - the unmet demand is many times the capacity that could be created in the core of the city.

I thought this was addressed.

Doubling of FSI doesn't mean a more congested Bombay, as the population of Bombay remains the same. It only means a more effective utilization of space.

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