How skyscrapers can save the city

Harvard real estate economist Ed Glaeser has an excellent essay in The Atlantic. The analysis and history is largely based on NYC, but the principles are universal. Example:

The relationship between housing supply and affordability isn’t just a matter of economic theory. A great deal of evidence links the supply of space with the cost of real estate. Simply put, the places that are expensive don’t build a lot, and the places that build a lot aren’t expensive. Perhaps a new 40-story building won’t itself house any quirky, less profitable firms, but by providing new space, the building will ease pressure on the rest of the city. Price increases in gentrifying older areas will be muted because of new construction. Growth, not height restrictions and a fixed building stock, keeps space affordable and ensures that poorer people and less profitable firms can stay and help a thriving city remain successful and diverse. Height restrictions do increase light, and preservation does protect history, but we shouldn’t pretend that these benefits come without a cost.

(…) But one of the advantages of building up in already dense neighborhoods is that you don’t have to build in green areas, whether in Central Park or somewhere far from an urban center. From the preservationist perspective, building up in one area reduces the pressure to take down other, older buildings. One could quite plausibly argue that if members of the landmarks commission have decided that a building can be razed, then they should demand that its replacement be as tall as possible.

The cost of restricting development is that protected areas have become more expensive and more exclusive. In 2000, people who lived in historic districts in Manhattan were on average almost 74 percent wealthier than people who lived outside such areas. Almost three-quarters of the adults living in historic districts had college degrees, as opposed to 54 percent outside them. People living in historic districts were 20 percent more likely to be white. The well-heeled historic-district denizens who persuade the landmarks commission to prohibit taller structures have become the urban equivalent of those restrictive suburbanites who want to mandate five-acre lot sizes to keep out the riffraff. It’s not that poorer people could ever afford 980 Madison Avenue, but restricting new supply anywhere makes it more difficult for the city to accommodate demand, and that pushes up prices everywhere.

Again, the basic economics of housing prices are pretty simple—supply and demand. New York and Mumbai and London all face increasing demand for their housing, but how that demand affects prices depends on supply. Building enough homes eases the impact of rising demand and makes cities more affordable. That’s the lesson of both Houston today and New York in the 1920s. In the post-war boom years between 1955 and 1964, Manhattan issued permits for an average of more than 11,000 new housing units each year. Between 1980 and ’99, when the city’s prices were soaring, Manhattan approved an average of 3,100 new units per year. Fewer new homes meant higher prices; between 1970 and 2000, the median price of a Manhattan housing unit increased by 284 percent in constant dollars.

Bad land use is not just a western problem. E.g., dynamic cities such as Mumbai are being crippled by wrong-head regulation. You know the traffic and congestion in Mumbai is mind-boggling. Did you know that this is largely due to a 1.33 maximum floor-to-area ratio?

The public failures in Mumbai are as obvious as the private successes. Western tourists can avoid the open-air defecation in Mumbai’s slums, but they can’t avoid the city’s failed transportation network. Driving the 15 miles from the airport to the city’s old downtown, with its landmark Gateway of India arch, can easily take 90 minutes. There is a train that could speed your trip, but few Westerners have the courage to brave its crowds during rush hour. In 2008, more than three people each working day were pushed out of that train to their death. Average commute times in Mumbai are roughly 50 minutes each way, which is about double the average American commute.

The most cost-effective means of opening up overcrowded city streets would be to follow Singapore and charge more for their use. If you give something away free, people will use too much of it. Mumbai’s roads are just too valuable to be clogged up by ox carts at rush hour, and the easiest way to get flexible drivers off the road is to charge them for their use of public space. Congestion charges aren’t just for rich cities; they are appropriate anywhere traffic comes to a standstill. After all, Singapore was not wealthy in 1975, when it started charging drivers for using downtown streets. Like Singapore, Mumbai could just require people to buy paper day licenses to drive downtown, and require them to show those licenses in their windows. Politics, however, and not technology, would make this strategy difficult.

Mumbai’s traffic problems reflect not just poor transportation policy, but a deeper and more fundamental failure of urban planning. In 1991, Mumbai fixed a maximum floor-to-area ratio of 1.33 in most of the city, meaning that it restricted the height of the average building to 1.33 stories: if you have an acre of land, you can construct a two-story building on two-thirds of an acre, or a three-story building on four-ninths of an acre, provided you leave the rest of the property empty. In those years, India still had a lingering enthusiasm for regulation, and limiting building heights seemed to offer a way to limit urban growth.

But Mumbai’s height restrictions meant that, in one of the most densely populated places on Earth, buildings could have an average height of only one and a third stories. People still came; Mumbai’s economic energy drew them in, even when living conditions were awful. Limiting heights didn’t stop urban growth, it just ensured that more and more migrants would squeeze into squalid, illegal slums rather than occupying legal apartment buildings.

Singapore doesn’t prevent the construction of tall buildings, and its downtown functions well because it’s tall and connected. Businesspeople work close to one another and can easily trot to a meeting. Hong Kong is even more vertical and even friendlier to pedestrians, who can walk in air-conditioned skywalks from skyscraper to skyscraper. It takes only a few minutes to get around Wall Street or Midtown Manhattan. Even vast Tokyo can be traversed largely on foot. These great cities function because their height enables a huge number of people to work, and sometimes live, on a tiny sliver of land. But Mumbai is short, so everyone sits in traffic and pays dearly for space.

Is it a surprise that Singapore has so few of these planning mistakes? Read the whole thing »