Category Archives: Cities

Is there such thing as an Islamic city?

Cairo at dusk

Cairo. Tehran. Karachi. What sets these cities apart in the world isn’t their arid climate or their massive populations. Rather, they’re all cities where Islam is the dominant religion. But are they Islamic cities? In other words, have the beliefs, rituals, and laws of Islam shaped cities in the Middle East and around the world?

The idea of an Islamic city was introduced by the French following Napoleon’s unsuccessful forays into Northern Africa and the Middle East. The French, thus exposed to Islamic cultures, grew a bit obsessed. But like many colonizers and would-be colonizers, they didn’t always get things right.¹

One of the developments of this decades-long fixation was the idea of an Islamic city. While the concept was probably bouncing around French salons for a while, William Marçais put it into words in 1928. He believed there are certain essential elements in any Islamic city. First and foremost is the mosque. Nearby there has to be a bazaar. There must also be a public bath where worshipers can prepare. William’s brother, George, elaborated some years later. Along with the bazaar, he added that booksellers must also sit next to the mosque. Farther out come the textile merchants, jewelers, hatters, furniture makers, and blacksmiths. It was all very elaborate and, in a way, a bit too orderly for reality.

The Marçais’ contemporaries wrote extensively about Islamic cities, but as sociologist Janet Abu-Lughod points out, many of them simply parroted the others without additional research of their own. And so the idea was perpetuated for several more years.

Toward the end of the 20th century, people started to earnestly question the idea of an Islamic city. Abu-Lughod and others, including Ahmad Bilal, argued that the forces that shape cities are never as simplistic as “Islam” or “Christianity.” Geography, climate, technology, society, and laws all play a role. Religion can, too—indeed it does on a smaller scale in Middle Eastern cities, influencing the design of homes and buildings—but it doesn’t enforce a strict blueprint.

Indeed, many of today’s Islamic cities are not shaped primarily by Islam, but by rapid urbanization. Cairo exploded from 2.3 million people in 1950 to over 10 million today (nearly 20 million if you count the metro area). The same thing happened in Tehran, which grew from around 1 million in 1950 to nearly 8 million today.

Oil wealth shapes others. In countries such as Saudi Arabia and the United Arab Emirates, ever-taller skyscrapers, massive malls, and expanding highways define their cities—and their populations, since construction is mostly done by huge pools of foreign laborers, many of whom come from nations with large Muslim populations like Egypt, Indonesia, and Bangladesh. Though they’re seldom awarded citizenship, they still bring their own unique urban experiences with them.

So can we say there is such a thing as an Islamic city? Grudgingly yes, but mostly no. There are cities that have been influenced by Islam, just as European cities were shaped by Christianity. But for the most part, cities in the Middle East and elsewhere with large Muslim populations have evolved just the same as cities have elsewhere—by adapting to their environment and their people.


  1. That is, perhaps, an understatement.

Photo by Frank Schulenburg

Sources:

Abu-Lughod J.L. (1987). The Islamic city – Historic Myth, Islamic Essence, and Contemporary Relevance, International Journal of Middle East Studies, 19 (02) 155-176. DOI: 10.1017/s0020743800031822

Ahmad B. (1995). Urbanization and urban development in the Muslim World: From the Islamic City Model to megacities, GeoJournal, 37 (1) 113-123. DOI: 10.1007/bf00814892

Bonine M.E. (2009). Middle East and North Africa, International Encyclopedia of Human Geography, 82-88. DOI: 10.1016/b978-008044910-4.00298-4

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In 40 years, will self-driving cars send us packing for the suburbs?

desert-suburb

At the end of 2013, the journal Cityscape put the following statement to contributors and asked their opinion of it: “In 40 years, the average person will live closer to her neighbors and farther from the ground than she does today.” This is a critique of one response. More to come…

Most urbanists will tell you that we’ll be living at higher densities sooner than you think. Nathaniel Baum-Snow, an economist at Brown University, is one of them. He cites a handful of reasons why he thinks we’ll all be living closer to our neighbors 40 years from now, including commute times, declining fertility rates, and stalled highway construction. Baum-Snow makes valid points, but many of his assumptions presume that the world 40 years from now, at least technologically, will look similar to today. Given the last 40 years, I’ll be surprised if that happens.

Self-driving cars are one of the biggest threats to the future of cities, and widespread adoption could single-handedly undermine one of Baum-Snow’s most compelling arguments—commute times, which he says will be a driving force behind increasing urban densities. As incomes have risen for many city dwellers—those in the top 50 percent, at least—the value of their commute time has also risen. Given Marchetti’s constant, which says that commute times tend to hover around 30 minutes each way, snarled traffic will force the wealthy out of the suburbs and back to cities. In a sense, we’ve already started to see that.

But self-driving cars could reverse that trend. As people’s commutes are freed up for other tasks, including work, they’ll stretch their daily trips, once again allowing them to live where they want. And as we’ve seen, people want to live where they have more space.¹ Compounding the problem is the fact that most early adopters are likely to be wealthy, the same people Baum-Snow says will be looking to drive less.

Working in cities’ favor, Baum-Snow adds, are declining fertility rates. Between 1967 and today, birth rates have fallen from 0.122 births per woman of childbearing age to 0.065, nearly a 50 percent drop. With people having half as many children, the need for space should decline. But as we’ve seen, that’s not necessarily the case. Between 1973 and 2012, median home sizes have grown from 1,525 square feet to 2,306 square feet, the same time that fertility was declining. In that same time period, median household income has risen almost $10,000 when adjusted for inflation, a nearly 25 percent increase.²

Then there’s the siren song of the suburbs—school quality. Suburban and small town school districts frequently outperform their urban counterparts. Baum-Snow notes that the quality of public schools in big cities has stabilized, at least, but that isn’t quite the same as improving. Plus, even if they do improve, urban schools will have to overcome the stereotype wrought by decades of poor performance.

(There is a simple fix, of course—invest in public education at all levels. Early childhood programs have shown great promise at preparing children of all backgrounds for full-time school, and education is the best chance many of children have to break free of poverty.)

Given these realities, I don’t think the future points to downtown, as Baum-Snow does. It’s true that city centers are the hot place to be, but density numbers don’t reflect the newfound enthusiasm. And trends in technology could shatter the many cities’ recoveries.

Despite that, I think many of us—at least, those of us not in the top few percent—will be living closer together. Not downtown, but in the sprawling inner suburbs that will be indistinguishable from the rest of the city, slogging through long commutes between home—which was convenient to the old job we got laid off from—and our new jobs on the wrong side of town.


  1. Home sizes briefly halted their inflation during the recession, but they’ve started to rise again.
  2. On top of that, interest rates are lower today than in the 1970s. That could change 40 years from now, of course.

Photo by Michael Colburn.

Source:

Baum-Snow, Nathaniel. 2013. “Changes in Urban Population Densities Over the Next 40 Years.” Cityscape 15(3).

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In 40 years, will we live in cities in the sky?

supertrees-singapore

At the end of 2013, the journal Cityscape put the following statement to contributors and asked their opinion of it: “In 40 years, the average person will live closer to her neighbors and farther from the ground than she does today.” This is a critique of one response. More to come…

Two visions. One dystopian, filled with social decay, segregation, and violence. The other optimistic, light, harmonious, and elevated. Jill Stoner, a professor of architecture at the University of California, Berkeley, offers them both as possible visions of a denser future. While she acknowledges that either is possible, she hopes for the latter.

To flesh out her dark version of the future, Stoner draws on a novel by British novelist J.G. Ballard. Having been crafted by a fictionist, it is captivating in its detail. There’s a new London skyscraper that houses wealthier residents as the floor count increases. Each income segment is buffered from each other in various ways, but they still find a way to wage class war against each other. The novel begins by starting at the end with the culminating event—a doctor eating another resident’s dog. That’s how low things have gotten.

It is, Stoner argues, a caricature of late 20th century views on skyscrapers. Once heralded as a way to save cities, residential towers in many cases ended up destroying much of what made urban areas successful. To Stoner, though, the skyscraper isn’t dead. While she sympathizes with those who favor “traditions of townships, neighborhoods, and gardens planted in terra firma behind firmly owned houses”—arguably the New Urbanists—she sees more promise in building up, way up. Because the idea failed once doesn’t mean it will fail again. In fact, she argues that it has to succeed because we can’t pretend that a neighborhood-centric mid-rise city is the only template.

Her grand vision, less vivid than that of Ballard’s but still reasonably compelling, is a city of towers linked by boulevards some 20 stories above the ground. Below, the ground has gone fallow, if you will, left to return to nature. Sort of a mashup of the aerial walkways of Star Wars’ Coruscant and Tyler Durden’s dream of wild freeways.

How likely is that in 40 years? Not very, a fact which Stoner admits, stating it’s more like 100 years off. But even then, will we all be living in skyscrapers, seldom touching the ground? It’s certainly possible, though I think it would require a transformative technology that we don’t have or can’t envision.¹ Right now, our lives are firmly rooted on the ground—or in software. We walk, we drive, we ride, we chat, we message. It all happens on—or under—solid ground. The comparatively little travel we do in the skies hasn’t exactly fostered density

Unless something radical changes in the next century, it’s unlikely that towers will play as central a role as Stoner envisions. Yes, we’ve inched toward her future in the last 100 years, but we’ve also backed away from it. Our cities—at least here in the U.S.—grow more dispersed every year, and self-driving cars, the current technology that’s most likely to change cities in the coming decades, is likely to hasten that trend. Time will tell, of course, but for now, I can’t see Stoner’s vision coming true.


  1. Those lofty visions of the future that we see in Star Wars and other sci-fi tales imply that aerial living arose because anti-gravity became commonplace. Only then were we able to really make use of the third dimension.

Source:

Stoner, Jill. 2013. “High Optimism.Cityscape 15(3).

Photo by z_wenjie

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Your carbon footprint may not be as low as you think

Tokyo buildings

High-density living—it’s an urbanist’s answer to climate change. Living close is a straightforward solution to a complex problem. One that’s probably a little too simplistic. While living in dense cities certainly does reduce your carbon footprint, the results may not be as dramatic as you suspect.

That’s according to a new research paper by Chris Jones and Dan Kammen, two University of California, Berkeley researchers who have extensively studied people’s carbon footprints. Their results show that moving from a carbon-heavy suburb to an ultra-dense city will only reduce your emissions by 35 percent on average. Yes, that’s a big number, but perhaps not as significant as we’re often led to believe. But fortunately lurking within their data is an even simpler—and maybe even more effective—way for metro areas to reduce their footprint.

Jones and Kammen have spent years honing their methodology for determining people’s carbon footprints. Jones is the lead scientist at the Renewable and Appropriate Energy Lab and Kammen is its director and a professor at the university. Together they’ve created one of the most detailed and accurate carbon footprint calculators available online. To develop that tool, they had to ask a lot of people a lot of questions about their lifestyles. With that experience, they’ve published a number of papers that lift the veil on our energy use, revealing which aspects of our lives produce the most greenhouse gas emissions.

Their latest paper is contains some seemingly unexpected results, all gleaned by modeling emissions for individual ZIP codes. For example, you might expect carbon footprint to fall commensurately with population density. After all, living in the boonies makes you pretty reliant on cars while living in the city frees you to take transit. But it isn’t so clear cut. People living far from cities and suburbs have fewer destinations and tend to buy less, driving down their overall footprint.

As population density increases, then, household carbon footprints rise initially, up to 3,000 people per square mile. After that point, emissions per household drop, though the trend isn’t linear, it’s logarithmic, which is to say it falls fast at first but then with plateaus.

Jones and Kammen found that the most carbon intensive places to live are about 15 to 45 miles from the center of the nearest major city.¹ Most households in these bands have higher incomes and more members, both of which are tightly coupled with carbon emissions in the U.S. Those households also have higher transportation footprints—50 percent more than city center households. Overall, suburbs account for half of the U.S.’s carbon footprint. Large cities contribute 30 percent.

No city can escape its suburbs. As long as people have the means and the desire, they’ll live in those sorts of places. So to reduce a metro area’s overall carbon footprint, Jones and Kammen say, you have to tailor solutions that will work for each region of the country and each part of the metro. To be successful, those solutions must work with people’s existing behaviors.

Take the suburbs, for example. “These locations are ideal candidates for a combination of energy efficient technologies, including whole home energy upgrades and solar photovoltaic systems combined with electric vehicles,” they write. Forcing someone to use transit changes their behavior, and people are resistant to that. But if you encourage them to use electric cars, that works within their existing behavior. It’s an easier sell.

The overall trend of population density and household footprints offers another option, too. Pushing densities above 3,000 people per square mile can lower emissions substantially. That’s the tipping point in Jones and Kammen’s curve. Beyond that, they declined sharply, but then plateau. In other words, to make an significant impact, we just have to live a little closer together.


  1. The lowest emission rural areas are on par with people living in some major cities, though the densest cities still have the smallest footprints per capita.

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How to save a dying city

detroit-ruin

Forty years ago, Detroit was doing pretty well. The auto industry was cranking, employment was high, wages were decent, and the city was packed. Today, well, not so much.

Forty years ago, Pittsburgh was doing pretty well. The steel industry was cranking, employment was high, wages were decent, and the city was packed. Today, well, it’s actually not doing so bad.

Both Rust Belt cities have a lot in common. They were heavily working class, and when manufacturing started moving overseas and automation encroached on what was left, people lost their jobs. When manufacturing jobs didn’t return, they left. Since 1970, Detroit has lost more than 45 percent of its population, Pittsburgh more than 43 percent. So what makes the two different?

Education, in a word. Today, a greater proportion of Pittsburgh’s residents have college or higher degrees compared with Detroit. That comparison comes by way of Dan Hartley, a Cleveland Federal Reserve economist, who crunched some numbers for four hard-hit Rust Belt cities—Detroit, Pittsburgh, Buffalo, and Cleveland—and arrived at some not-surprising conclusions. Though most of his analysis focuses on Cleveland, it was the disparities between Detroit and Pittsburgh that caught my eye.

In 1970, before the Rust Belt grew rusty, both cities were at the tops of their games. Median household income in Motor City was $46,438,¹ not far off from today’s nationwide median of about $51,000. For a working class city, that’s not bad. Pittsburgh was in good shape, too, with a median income of $37,477. Home prices were similarly competitive. In economic terms, both Detroit and Pittsburgh were typical American cities.

But over time the two diverged. By 2006, the year in which Hartley’s analysis is based, median household incomes were down 35 percent in Detroit but only off 10 percent in Pittsburgh. Home prices mimic that on a lesser scale, with Detroit up 9 percent and Pittsburgh up 13 percent. Where they differ is in education. In 1970, 6 percent of Detroit’s population had a college or higher degree. In 2006, just over 11 percent did. Pittsburgh, on the other hand, more than tripled its share, going from 9 percent in 1970 to over 31 percent in 2006.

In that time, the Steel City invested heavily in wooing healthcare companies and was reasonably successful at it. But that shift would have stumbled if the city hadn’t already had a strong educational foundation. Both Carnegie Mellon and the University of Pittsburgh are located in the city, providing plenty of local college grads looking for employment. Detroit has Wayne State, which is not a bad school at all, but it can’t compare with two, high-reputation schools like Carnegie Mellon or the University of Pittsburgh, which together have 12,500 more students than Wayne State.

If you look closely and in the right places, you quickly notice that education is the cornerstone of many booming cities and regions. Silicon Valley wouldn’t be what it is today without UC Berkeley or Stanford, and the Boston area wouldn’t be a hub of robotics if it wasn’t for MIT. If you want a thriving city, focus on education. I won’t say everything else is just details, but smart people have a way of figuring those out.


  1. All figures are in 2009 dollars.

Source:

Hartley, Dan. 2013. Urban Decline in Rust-Belt Cities. Economic commentary, Cleveland Federal Reserve Bank.

Photo by migee_castaneda

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How to keep the economy growing when our population is not

empty-street

Zero population growth is a period in future human history that is both hoped-for and feared. If we don’t get to that point, the world could literally become overrun with humans, straining already taxed resources like fresh water and farmland to the breaking point. But with zero population growth, the global economy—heavily reliant on a young and expanding workforce—could collapse. No matter what we hope, according to projections by the United Nations, it’s likely that within the next century, the global population will level off or even shrink.

It’s a prospect that vexes demographers and economists alike, which is a sharp change from the 1960s, when we feared rampant population growth. Now, we fret over the opposite, and for good reason. While stabilizing or declining numbers will certainly ease the burden on the environment, no one knows how society will function in a future with fewer people. Globally, it’s never happened before. Locally, we’re starting to see it in some countries such as Japan, which has been stuck at about 127 million for the last decade. By 2045, it will drop to 105 million, and it’s already affecting Japan’s long-term thinking—some economists are questioning the need for the country’s proposed maglev system if there are fewer people to ride it.

There’s another, more fundamental problem that zero or negative population growth poses, though—the transfer of knowledge. We know that when people come together, they tend to create new technologies, skills, and knowledge. Cities are hubs of innovation, universities are great factories of scholarship, and even smaller groups can inspire people to create wonderful things. Perhaps more importantly, the number and strength of our connections are vital for passing knowledge on to others, two recent studies suggest. Without those connections, our society could fall rapidly behind. Fortunately, the research also suggests a way to escape the declining population trap.

Ed Yong, who covered the two studies for Nature News, pointed out that the papers provide independent validation of the idea that cultural knowledge is tightly correlated with group size and connectedness. They approach the problem from slightly different angles. The first study examined whether group size affected how well cultural tasks—in this case making an arrowhead or a fishing net—were passed down from one group to the next. In every instance, groups of eight or 16 performed significantly better than groups of two or four. Bigger groups also developed better and quicker ways of making the arrowheads.

The second study tested how interpersonal connections affected performance of a task, in this case either duplicating an image on a computer or recreating a series of knots used in rock climbing. In the drawing experiment, which tested the creation of knowledge, inexperienced people started off, going by trial and error. Later generations of participants could watch earlier people’s attempts and use that to hone their skills. Some were given the opportunity to observe five different attempts, others were only given the chance to see one. Those who had access to five examples recreated the drawings more accurately than those who could only see one.

The knot-tying experiment tested how cultural knowledge was maintained. The first generation of participants was trained by an instructor. Later generations watched footage of previous people tying the knots. Those who could watch five examples were twice as good at tying the knots as those who could only watch one example. The more connections, the more faithfully that knowledge was passed on.

Together, these two papers make a strong case for social savvy being the foundation of our complex culture. The first paper—the one with the arrowheads and fishing nets—confirms experimentally what many scientists suspected, that larger groups are both more proficient and more innovative. But the second study really intrigues me. It’s the one that, I believe, offers a way to keep our economy surging when our population begins to level off or decline.

The key to that is social connections. The more connected people were in either experiment of the second study, the better they performed, whether that be for maintaining knowledge or advancing it. Following that thread, it stands to reason that we can successfully decouple economic growth from population growth if social connections continue to increase. So even if our numbers decline, as long as our connections do not, we will at the very least be able to maintain our cultural knowledge and hopefully our standard of living.

To do that, we need to meet three challenges. First, the trend toward urbanization needs to continue. Cities foster connections between people, and the more people that live in cities, the more cultural knowledge we can maintain. Second, the internet needs to be everywhere. As the internet has taken hold, it has connected people in ways never before imagined. It’s now easier to access scholarly articles, stay in touch with friends and family, and partner with peers around the globe, all of which serve to maintain and increase our collective knowledge. Finally, as cities swell, we need to make sure they are physically connected as seamlessly as possible. Large cities can provide a wealth of opportunities, but no single city can offer them all. Being able to zip from one to the next will be vital for our cultural survival.¹

If we can meet those three challenges, and if social connections continue to multiply as population stabilizes or declines, then I think we’ll have a good chance of maintaining economic growth and raising standards of living.


  1. I would argue that this implies that Japan’s maglev system will be even more important if the population declines as is predicted. They’ll need more connections, not fewer.

Sources:

Derex M., Beugin M.P., Godelle B. & Raymond M. (2013). Experimental evidence for the influence of group size on cultural complexity, Nature, DOI:

Muthukrishna M., Shulman B.W., Vasilescu V. & Henrich J. (2013). Sociality influences cultural complexity, Proceedings of the Royal Society B: Biological Sciences, 281 (1774) 20132511-20132511. DOI:

Photo by eioua

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How cities change the weather

Storm-over Kuala Lumpur

Late in the day on June 13, 2005, a thunderstorm was bearing down on the city of Indianapolis. As the main cell approached from the southwest, it reared up, convection currents pushing it higher and higher until it towered over the city. Luckily for Indianapolis, the cloud threatened more than it menaced, eventually dumping just an inch of rain on suburbs and farm fields to the northeast. On the surface, it may not have seemed particularly special. But for meteorologists studying the storm, it was perfect.

What set that storm apart from others, they suspected, was the fact that it passed over Indianapolis. The fact that the city was there—the subtle but significant change it made to the texture and composition of the Earth’s surface—was enough to alter the structure of the storm. Using a model they built to test the city’s impact, meteorologists couldn’t accurately simulate the June 13 storm without Indianapolis.

Humans altering the weather is the stuff of science fiction. (Not climate, mind you. That’s unfortunately all too real.) Not that we haven’t tried—cloud seeding, while not as promising as once thought, is still used on occasion to coax more precipitation from the sky or to wring clouds dry, as was the case during the Beijing Olympics. Cloud seeding is small scale stuff, though, and the amount of effort required makes it unsustainable over the long term. But while tactical, widespread weather control remains beyond our grasp, we routinely change the weather around the world simply by living in cities. And most of us don’t even know it.

The most common—and well known—way that we change the weather is through the urban heat island effect. In an urban heat island, a city’s mass of asphalt and concrete and lack of tree cover traps and holds heat. That effect may drive other shifts in the weather, including the change in structure of the June 13th storm over Indianapolis. Heat rising off a city, meteorologists think, increases convection within storms, pushing the storm cloud higher faster and raising its reflectivity core, or the size and distribution of rain droplets within the cloud. In some cases, cities can even split the reflectivity core—the buildings exert drag on the atmosphere, which disrupts the storm’s airflow.

Von Karman vortexes near Guadalupe Island

That a city’s physical structure can affect a massive system like a thunderstorm may seem unlikely, but it’s not improbable. Scores of satellite images have captured islands cleaving clouds, creating successive swirls downwind, a phenomenon known as the Von Karman effect. No one has seen cities create disturbances as charismatic as the Van Karman effect, but Marshall Shepherd, a professor at the University of Georgia and president of the American Meteorological Society, told me that one of his students has found traces of it in his research models. Unfortunately, the results weren’t strong enough to include in a publication.

Apart from changes in cloud structure, there’s also some evidence that cities change the amount of rainfall a storm produces. A large field experiment carried out in North America in the 1970s, known as METROMEX, concluded that cities increased cumulative precipitation by 5-25 percent, most of which fell downwind of the city. Size mattered, too. Bigger cities tended to induce more rainfall that fell over a larger area. Since then, some studies have disagreed, claiming there’s no change, but an even larger number seem to confirm the patterns found in METROMEX. Depending on the region, these new studies found that cities may increase rainfall by up to 60 percent, several-fold more than previously thought. What’s causing that? Any number of factors, including aerosols from pollution, the urban heat island, and changes in airflow over buildings, could be driving the urban rainfall effect. But to date, no one can definitively explain why it occurs.

When you add it all up—and throw in a few other variables I haven’t discussed, including lightning strikes and wind speeds—it’s clear that cities have an undeniable impact on the weather. That many of those effects extend far beyond political boundaries should only reinforce the idea that cities and their countrysides are inextricably linked.

Sources:

Shepherd J.M. (2013). Impacts of Urbanization on Precipitation and Storms: Physical Insights and Vulnerabilities, Climate Vulnerability: Understanding and Addressing Threats to Essential Resources, 109-125. DOI:

Niyogi D., Pyle P., Lei M., Arya S.P., Kishtawal C.M., Shepherd M., Chen F. & Wolfe B. (2011). Urban Modification of Thunderstorms: An Observational Storm Climatology and Model Case Study for the Indianapolis Urban Region, Journal of Applied Meteorology and Climatology, 50 (5) 1129-1144. DOI:

Photos by fehlart and NASA.

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The uncanny valley of commerce, and what it means for your community

target

Your grocery store. Google. Target. What do these three have in common? They all gather personal information, and they all do it—and I’m paraphrasing here—”to serve their customers better.” In the case of your grocery store, they profile your habits to get you in the store, to buy more things. Same with Target. Google mines your personal information to hit you with ads you’re more likely to click on. In each case the company is looking to make money off their knowledge of you. It’s not that different from the way business used to be run. With one big exception.

In the past, when you visited a store, you may have known the owner. The owner of the hardware store knew you were a repeat customer, so he may have given you a deal on a new drill, knowing you’d probably be back for screws, lumber, and glue. Or maybe the owner of the shoe store, which you’d been shopping at for years, would cut you a deal on your kid’s new sneakers. In each case, they wanted to keep you as a customer. Your repeat business ensured future revenue, which is more valuable than a few extra dollars today.

Big businesses know this, too. They know that repeat customers are among the most profitable—that’s why there are frequent flier programs, club memberships, and loyalty cards. But somewhere along the line, they also realized they were sitting on a treasure trove. With every signup, with every logged purchase, people gave away personal information that hinted at what kind of customer they were. Companies started to mine that data, looking for patterns that would reveal even more intimate details. Target is perhaps best at this among large retailers, famously predicting their customers’ pregnancies weeks before they even know.¹

And therein lies the problem. Massive databases of personal information allow companies to do the same things businesses did in the past—offer deals to loyal customers, personalize offerings, and so on—but they do so without any sort of meaningful relationship. “Steve” may be genuinely interested in your budding family. Target is not, except to sell you more diapers. These companies are able to do make personal offerings, but in such a way that it’s clear no human is behind them. Call it the uncanny valley of commerce.

In commerce, though, relationships matter. That’s part—a large part, I’d argue—of what makes us queasy about data mining. Personalized deals are one thing when someone you know is offering them. But in the absence of a person we know, we don’t know what’s behind the gesture. Without a personal relationship, we can’t trust that these companies have our best interests in mind.

Now, things weren’t all sunshine and daisies in the past. Small operators used to disappear in the middle of the night, absconding with their customers’ money.² And while personal relationships can keep some vendors in line, it holds little meaning for others. It’s true that big companies can be held more accountable in many circumstances, but that doesn’t mean we trust them any more. There’s a reason they’re called “faceless corporations.”

Massive multinationals exist because of economies of scale, which has been shifting our economy from one driven by small proprietors to one dominated by large companies. It’s also changing the relationship between seller and buyer. And just as economies of scale have transformed businesses, they’ve also fostered population growth. The two go hand-in-hand. Because we’re now so numerous, we’re easier to deal with in bulk than one-on-one. But I suspect that transformation is also subtly altering our communities, displacing some of the relationships that were built around proprietors and customers. It’s not clear to me what’s taking their place.

There will always be opportunities for small businesses. How many? We don’t know. But there are certain to be fewer. Personal relationships in commerce will continue to wane, and I’m guessing it’ll have an enormous impact on our lives, our finances, and our communities.


  1. Charles Duhigg exposed some of Target’s secrets in his book The Power of Habit, an excerpt of which you can read online.
  2. Though truth be told, the same thing can happen today. It’s called bankruptcy.

Photo by Mr. T in DC

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solar-roof

It’s no secret that living in the suburbs is a tad energy intensive. Low-density living practically requires owning and driving a car, which consumes a large portion of suburban households’ energy budgets. But there’s an upside to sprawl, too—plenty of space for solar panels.

Researchers in Auckland, New Zealand asked what the energy balance of the suburbs would look like if photovoltaic solar panels were widespread and how that would compare with denser urban centers. They looked at a range of dwelling densities, from a low of about 6 per acre in the outer burbs to a high of 52 per acre in the city. The researchers then imagined what would happen if solar panels were installed in every location that would be viable, typically on rooftops facing north and west (this is the southern hemisphere, after all).

In dense urban areas, the area available for solar panels was low on a per capital basis. In the suburbs, that flipped. The difference was so extreme that solar panels in dense parts of the city could only meet a fraction of the demand. But in the suburbs, there was actually an excess of electricity generated, so much so that households could own—and charge—electric cars and still not consume it all.

Now, there are some caveats to this study, namely that Auckland is a relatively sunny place despite its frequent seasonal rain showers. Solar radiation in the city is 1663 kW h/m2/y, which compares favorably with Barcelona in sunny and solar-friendly Spain, which averages 1613 kW h/m2/y. Not everywhere has the potential of those places. But those that do, particularly in the Southwestern United States, are also hotbeds of sprawl. Widespread adoption of solar power would certainly change energy budgets there.

Solar-powered suburbs wouldn’t be all green—there’s still the issue of habitat disruption and fragmentation. Yet those are concerns for solar power installations, too. There’s still strong demand for low-density living, so if we were to supplant large solar installations with solar panels with houses under them, that may not be such a bad trade-off.¹ Coupled with habitat-rich yards and parks, such developments could even be more ecologically productive than a solar plant (though still less than undeveloped land). That won’t stop some people from ragging on suburbs, but they’ll have a few less reasons to do so.


  1. I’d still like to see a direct comparison of how much less land is required for a solar installation compared with a solar-powered burb before making any final conclusions—this study didn’t go into that.

Image courtesy of John Callas

Source:

Byrd H., Ho A., Sharp B. & Kumar-Nair N. (2013). Measuring the solar potential of a city and its implications for energy policy, Energy Policy, 61 944-952. DOI:

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How self-driving cars will change cities

America’s suburban future

What’s more energy efficient, shopping online or in stores?

Back in 1998, in the heyday of the dot-com bubble, Pets.com launched. The site was perhaps best known for its ad campaign which featured a sock puppet dog. The company’s business plan was to deliver pet supplies to people’s homes. The site was a horrendous failure, and its bankruptcy served as a sort of warning sign to would-be e-commerce entrepreneurs for years to come.

Yet if we fast-forward to today, home delivery of everyday items seems, well, everyday. Pets.com may have had a flawed business model, but the basic principle behind it was sound. Amazon weathered the dot-com bust, as did a handful of other e-commerce sites. Many brick-and-mortar retailers have successful websites. Even trips to the grocery store are being replaced with deliveries from companies like Peapod, FreshDirect, and even Amazon.¹ But with the boom in online shopping for everything from jeans to Jujyfruits, people have grown concerned that e-commerce’s simplicity comes with an environmental price.

The concern mostly centers around the delivery’s carbon footprint. All those UPS trucks rumbling down every street in American surely can’t be a good thing. They’re big, their loud engines must suck tremendous amounts of fuel, and what happens if you’re not home to pick it up? Fret not. Your Amazon delivery probably has a trimmer footprint than a simple trip to the store.

A number of studies have looked at the difference in carbon emissions between items ordered over the internet and those purchased the old fashioned way.² One straightforward study collected data from a clothing retailer in Germany that sold their wares both in stores and online. Researchers surveyed over 700 in-store shoppers at two locations and 40,000 online orders. They then stratified their results based on travel distances to the store and distances from the warehouse to customers’ homes. At short distances—less than 8.6 miles or 14 km one-way—in-store shoppers slightly edged out online customers per transaction, about 73.8 g CO2 vs 77.9 g CO2. But over that, online shoppers’ footprints remained relatively stable while store goers emissions skyrocketed to as high as 451.4 g CO2 per transaction if they had to travel over 62 miles or 100 km.

Another more comprehensive study from the U.K. looked at the “last mile,” or the last journey of an item to a customer’s home. Researchers focused on non-food items, such as books, CDs, clothing, cameras and other household items. They also took into account how a person traveled to the store—car, bus, walking, or other public transportation—the frequency with which items are returned, and how requiring signatures for packages affects the rate of successful deliveries.³ If you want to reduce your carbon footprint, their results were unequivocal: Shop online. If you drove to the store, you’d have to buy 24 items to make the trip equal to the carbon footprint of just one item ordered online. If you took the bus, you’d have to buy eight.

Why are brick-and-mortar stores so inefficient? It turns out that transporting people to the store to select something and then getting them back home again requires a lot of energy. You also have to consider that items sold in stores were distributed from a central warehouse. When you place an order online, that trip transforms from one to the store to one directly to your home. Plus, delivery services optimize their routes to waste the least amount of fuel. Everyday shoppers don’t think in that level of detail. Even if you combine trips, which many of us are terrible at doing, you’d have to buy a lot of stuff per trip to equal the efficiency of a delivery.


  1. I subscribe to a monthly delivery of cereal from Amazon—it’s cheaper and one less thing I have to worry about at the store.
  2. Most of them considered European consumers, so you can assume that whatever inefficiencies are racked up for in-store purchases can be inflated for American consumers, who use less public transit and have less fuel efficient vehicles.
  3. Requiring signatures decreases the first-time delivery rate substantially, from as low as 2 percent for no signature to as high as 30 percent with a required signature.
  4. UPS’s famous “no left turns” rule is a testament to that.

Sources:

Edwards J.B., McKinnon A.C. & Cullinane S.L. (2010). Comparative analysis of the carbon footprints of conventional and online retailing: A “last mile” perspective, International Journal of Physical Distribution & Logistics Management, 40 (1/2) 103-123. DOI:

Wiese A., Toporowski W. & Zielke S. (2012). Transport-related CO2 effects of online and brick-and-mortar shopping: A comparison and sensitivity analysis of clothing retailing, Transportation Research Part D: Transport and Environment, 17 (6) 473-477. DOI:

Photo by lordferguson.

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How self-driving cars will change cities

Google self-driving car

Google made big news last year when it announced that its self-driving cars had logged 300,000 miles, all of which were accident free. Suddenly, self-driving cars weren’t science fiction anymore. People began to imagine futures in which they hopped in, entered a destination, and kicked back. We’re not there yet—autonomous vehicles will have to log an estimated 300 million miles before we can be confident they’re as safe as regular drivers¹—but we may be within a generation or two. It’s entirely possible that babies born today will be among the last who feel they have to learn how to drive.

Just as the automobile began reshaping cities a century ago, the self-driving car will change urban areas yet again. But like the advent of the automobile, it won’t happen all at once. The revolution will happen in stages, and we’re already in the first. Cars can now park themselves, keep you in your lane, brake when traffic slows, and accelerate when it moves again. Many expensive cars do all of the above and more. Luxury vehicles are often testbeds for new technologies, and it’s unlikely that full autonomy will be any different. The first fully autonomous car for mass consumption will probably be quite expensive. When the first of its kind leaves the dealer lot—with the only driver input being a destination—we’ll have entered the second stage.

When self-driving cars are the rule, not the exception, we’ll be in the third stage. There’s no doubt the technology will trickle down—perhaps strikingly fast in this case, if the trickling down of today’s electronic nannies is anything to go by. Soon, new cars in all price segments will drive themselves. Purists will howl, but commuters will rejoice.

The benefits of stage three should be obvious to anyone who regularly drives. Parking will be a breeze—the car will drop you off and go find a spot on its own. If automation is combined with a smart parking system, traffic in big cities could drop by 30 percent—the proportion of cars in city centers currently circling for a space. Commuting, too, won’t be half the chore it is today. That time wasted in traffic? Wasted no more. Take a nap, eat breakfast, catch up on reading, text your friends.² You get the idea. Unless energy prices skyrocket, those far flung suburbs will regain some of their luster. The surge in commuting coupled with the higher densities allowed by self-driving cars³ will make today’s crowded freeways seem spacious by comparison.

We can feel pretty confident about these predictions, I think, because they’re pretty similar to how we use cars today. At some point, though, we’ll start thinking about cars differently. If cars can drive themselves around, passengers or not, what’s the point in owning your own car? Why not lease one from a pool? Welcome to stage four. Schedule it for your daily commute—perhaps with a price break for carpooling—and request one on-demand for more unpredictable needs. If wait times are short enough, it’ll be an attractive proposition.

Automakers, of course, have the most to lose and the most to gain. If they navigate this transition poorly, they won’t fare well. People will need fewer vehicles if they’re buying timeshares, and the market for automobiles will plummet. But if automakers can tackle the logistics of a such a system, they’ll make a killing.

At this point, the lines between private and public transit will start to blur. What I described above bears a resemblance to personal rapid transit, or PRT. A dream of the 1960s and 1970s, PRT consisted of small pods, hailed on demand, that whisked passengers to their destinations along monorails or traditional rails. The main difference between PRT and self-driving car subscriptions is that the self-drivers won’t need new tracks or dedicated rights-of-way—they can use existing roads. The efficiencies in this system will be massive. Cars can be delivered and routed as needed, and they can be used more consistently throughout the day, picking up new passengers after dropping others off. Parking lots can be largely eliminated and replaced by central facilities where the fleet will return for refueling and maintenance. Streets can be narrowed, asphalt lots reclaimed.

There is one big difference between self-driving car systems and PRT, though. PRT, as it is typically envisioned, is publicly-owned and maintained. In all likelihood, that won’t be the case with self-driving cars. Automakers and rental car companies are best positioned to take advantage of the self-driving revolution. Both already have portions of the subscription part down—leases and rentals—but the logistics will pose a real challenge.

Regarding privatization, Allison Arieff, editor at SPUR, raises an important point—how will self-driving cars influence social equity? “If you could afford a BMW before,” she writes, “you’ll be able to afford a subscription to BMW’s suite of offerings in this scenario.” She’s absolutely right—there are certain to be varying price points. That’s just how markets operate. But don’t count on the self-driving market looking exactly like today’s auto industry.

The strongest competitor will be the company with the widest network and the highest availability of vehicles. In this regard, the market for self-driving vehicles will be more similar to the cell phone industry than today’s automotive industry. Today, vehicles are sold on the strength of their quality and features. Tomorrow, subscriptions to vehicles will be sold based on the reach and availability of their network. Within each network there will certainly be a wide-variety of vehicles available depending on how much you’re willing to pay. But niche automakers won’t succeed unless they dramatically scale up their network.

There are potential downsides to self-driving cars, of course. It’s very likely that the poor will be left out yet again. Cars are costly to buy and maintain. Will self-driving cars be any different, cost-wise? The poor probably won’t be able to afford plans that provide high availability, limiting their mobility. Companies with the widest networks and most cars will probably attract the most customers. Smaller players will be either forced out or bought out, concentrating today’s highly competitive automotive market; tomorrow’s self-driving car industry could quickly devolve into an oligopoly. When that happens, be prepared for wave after wave of profit-driven price-hikes.

Throughout all this, cities will be adapting. For a brief period, it’s possible that cars will function in cities the way we had always hoped they would—traffic will flow more smoothly, parking be less of a headache. But that will only be for a brief window. Revolutions in mobility have a tendency to decentralize populations rather than concentrate them. Sprawl may become even more acute than it is today.

When people stop owning cars, the line between public and private will blur further. Who will pay for the upkeep of roads, consumers or companies? What about parking spaces? Will private companies be able to take advantage of free parking, as individuals do today? Or will free parking be a thing of the past?

Parking lots may become passé, but there will be a new need for vast facilities to store, clean, and maintain self-driving cars. Given the realities of real estate, those facilities will probably sit on the outskirts of town. Highways would still be jammed during morning commutes, only there may be two pulses of traffic instead one—the first consisting of empty cars fetching their masters, the second ferrying them to work. The added convenience and efficiency of self-driving cars could raise demand, too, bringing even more cars on the road. Self-driving cars can make more efficient use of roadways, but those benefits may quickly be erased. Prepare for another round of highway expansions.

Where’s public transit in all of this? That’s a good question, and one I’m not sure anyone has adequately answered. It’ll probably still exist, though in what form I have no clue. Who will ride it is similarly up in the air, but motivations will probably remain the same—time, expense, and convenience. If mass transit can best self-driving cars at one or more of those, it’ll retain its place in the mix.

Two or more of these stages in the self-driving revolution will probably happen during our lifetimes. Changes to cities will lag, though not by much. When the automobile first caught on, cities quickly changed pedestrian laws, made way for parking, and, within just 50 years of the first mass-produced automobiles, tore down entire neighborhoods to build highways. Will the self-driving car precipitate such drastic changes? Perhaps. We’ll find out soon enough.


  1. Given the behavior of some drivers, that may come as a shock.
  2. Though to be fair, plenty of people do three of those four things on their commute already. I’m sure some have dabbled in the fourth.
  3. If cars can communicate their intentions to one another, they can be driven safely in tighter formations.
  4. Incidentally, BMW is already experimenting along these lines by providing owners of the i3 electric car access to X5 SUVs and other fossil fuel powered vehicles.

Photo by Google.

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When everyone lives in a city

How population density affects mortality

Dark city

If you want to live a long time, where should you reside, the city or the countryside? There are compelling arguments to be made for both. In the city, you could be the victim of a crime; in the country, an accident of man or nature could claim your life. Regardless of the various marks for and against, overall death rates are neither higher nor lower in the city than in the countryside.

But suicide rates are a different story. A couple of years ago, I covered the topic in some detail, drawing on three published studies. I discovered that suicide rates are higher in less populated areas for a couple of reasons. One is access to weapons—there tend to be more of them in the countryside, and they’re an awfully effective way to end a life. But more significant than that is one’s mental state. People with mental disabilities are more likely to take their own lives, and there is less access to mental health resources in less densely populated areas.

That’s not all, though. A new working paper published to arXiv.org by a motley crew—two insect ecologists, a systems scientist, and a theoretical physicist—adds a new wrinkle to the conundrum of mortality rates and population density. Like many other researchers, they found no overall link between mortality and population density. But once they limited their sample to young people, they saw rates of suicide and, to a lesser extent, accidental death skyrocket at lower population densities. Accidental deaths are somewhat easy to explain. In low-density areas of developed countries, driving is common, as is driving at high speeds. Accidents at higher speeds are more likely to be deadly, and young, inexperienced drivers are involved in more accidents. More puzzling, though, was what happened at higher densities. Above 777 people per square mile (300 per square kilometer), suicide rates flattened.

As a raw number, that’s not very high. A city with a population density that low is hardly a city. But a county or state at or above that number is dense, which is what the researchers used—U.S. counties, Japanese prefectures, French départements, and so on. The sort of places that have those population densities contain some real cities or metro areas—San Diego County in California and Denton County in Texas, which is part of the Dallas-Fort Worth metro area.

The reasons for this floor remain illusive. The researchers think social bonds may play a role, citing a “stay alive” effect that biologists see in lab-grown cell populations, where cells that don’t receive constant prods from companions commit suicide. Cities, they say, provide equivalent prods; it’s as though the mere fact of interacting with other people reminds you to stay alive. It’s an intriguing notion, but it’s obviously not a perfect analogy since some people can live for a very long time without constant prodding. Plus, none of the authors of the paper are sociologists or anthropologists—their conclusions are a bit speculative without some support from those fields. Maybe they’re looking for someone in one of those fields to collaborate. Currently, the paper is merely in working form, meaning it hasn’t been peer reviewed. The authors have put it out there so their peers can propose ways to improve it.

Regardless, the floor in suicide rates they’ve found is intriguing. There’s bad news and good news in that result. The bad news is that adding social bonds by increasing population density doesn’t seem to affect suicide rates. To have any effect on that, we’ll need more robust social services to catch the people in danger of slipping through the cracks. But the good news is that there doesn’t appear to be a point at which the trend reverses—massive cities do not, it appears, drive us to the brink.

Photo by nosha.

Source:

Wang, Lei, Yijuan Xu, Zengru Di, and Bertrand M. Roehner. 2013. “How are mortality rates affected by population density?” arXiv: 1306.5179v1

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A cautionary tale from Port-au-Prince

Man attempting to douse a fire Port-au-Prince after the 2010 earthquake

It was the evening of January 12, 2010, and Kathleen Tobin had just landed in Chicago’s O’Hare International Airport having come from Port-au-Prince, Haiti. Tobin is a historian at Purdue University Calumet in Hammond, Indiana, and she had been visiting Haiti for research. Shortly after getting off the plane, she heard that a massive 7.0 earthquake had struck only 16 miles west of Port-au-Prince, where she had been mere hours before.

The earthquake had leveled large portions of the city. The Haitian government estimates 100,000 houses were destroyed and another 200,000 were damaged. Some were informal housing units—commonly known as slums—but some were also legal dwellings. Regardless of their legal status, most of the buildings that collapsed in the earthquake were poorly built using brick and concrete with little to no steel reinforcement, the sorts of structures that are death traps when the ground starts shaking.

Tobin, shaken by the ordeal, set out to uncover historical trends and coincidences in Haiti that made the earthquake so lethal and destructive. Haiti has a long history of governmental ineptitude and corruption, both of which Tobin found contributed to the devastation. But she also discovered that the problems wrought by government failures were magnified by an exploding urban population. Haiti’s government and economy were intensely concentrated in Port-au-Prince. All of the country’s eggs were in one sagging, moth-eaten basket. One disaster there would send shockwaves throughout the country. Which, of course, it did.

Haiti, like nearly every other country, has gone from mostly rural to largely urban in the past several decades. But in Haiti, the roots of that trend extend back to the early 1800s. Then, the new republic was centered on Port-au-Prince and Cap-Haïtien, the two major ports, as a result of the country’s export economy. The trend continued in the 20th century. The U.S occupied the country in 1915 after a large number of political assassinations and in the process discouraged peasant farming in favor of other economic pursuits that would ostensibly integrate Haiti into the world economy.¹ When the U.S. left in 1934, Port-au-Prince was filling up. Not long after, concerns grew about the state of housing in Port-au-Prince.

The outlook wasn’t rosy when urban migration picked up in the 1960s. There weren’t enough jobs in the city for the number of people who lived there, but the situation in Port-au-Prince was still better than the countryside. People flocked to the capital at such a rate that by 1996 Haiti’s population was the most concentrated in the world.

The dictatorships of the two Duvaliers—François from 1957 to 1971 and his son Jean-Claude from 1971 to 1986—did little to help. Corruption became ingrained and governance suffered. The countryside was largely forgotten, with the exception of taxation. Under the Duvaliers, nearly 80 percent of government revenues came from taxing peasant farmers. The wealthy, who mostly lived in the cities, were barely touched. Basic services foundered. There hadn’t been a census since the 1950s, and even that one may have been off by as much as 15 percent. Port-au-Prince hadn’t had an official urban plan since the 1930s. Building codes were few, weak, and generally not enforced. Land records were spotty, so people built whatever shelter they could wherever they could find space.

When the earthquake struck in 2010, nearly 30 percent of the country’s population lived in the Port-au-Prince metro area. But even that large number fails to underscore just how deeply the nation relies on that one city. The nation’s government and economy are almost entirely dependent on the capital.

It’s a cautionary tale for countries with keystone cities—England with London, Japan with Tokyo, South Korea with Seoul—and countries with vast slums and impoverished countrysides—much of sub-Saharan Africa, Bangladesh, Brazil. While many countries with vital capitals are better prepared than Haiti—it’s hard not to be, given that the country has consistently ranked at the bottom in terms of infrastructure—a plan for resiliency would be wise. Japan, for example, drew up plans for a backup capital after the Tohoku earthquake and tsunami. The proposed location is farther from the coast and higher in elevation.

Haiti, of course, never had the luxury of considering a backup capital—it didn’t even have a functioning primary capital. It still doesn’t. More than three years after the earthquake, over 300,000 people still don’t have permanent homes.² But neither do they have anywhere to go. In Haiti, life is in Port-au-Prince, whether that life is comfortable or not.


  1. Shades of the Monroe Doctrine and colonialism, to be sure.
  2. That number would be greater if some 60,000 hadn’t been forcibly evicted from the tent cities.

Note: Tobin has also written a book, Brush with Haiti, about her research and experiences there.

Source:

Tobin, Kathleen A. 2013. “Population Density and Housing in Port-au-Prince: Historic Construction of Vulnerability.” Journal of Urban History. DOI: 10.1177/0096144213491224

Photo by the United Nations.

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Science of cities, at long last

View from atop Atago Green Hills Forest Tower, Tokyo Cities, it seemed, had been abandoned by science. When all the other disciplines and systems were being quantified and theorized, cities were largely ignored. Cities didn’t have a grand unified theory or a theory of everything. Hell, for the most part they didn’t even have a theory of something. People pieced together bits and bobs here and there, but there was no wide-scale model to describe what is the greatest collection of systems ever devised by humanity.

That may be changing, though. Luis Bettencourt, whose work I’ve written about before, published a new paper today in which he claims to have developed a unified theory of the city. Like his previous research, it focuses on scaling in cities—what patterns and processes share mathematical similarities across cities of all sizes. Bettencourt takes a functional approach, studying what he believes are cities’ reasons for being, social interaction.

Bettencourt believes there are four sparks that cause cities to form—the mixing of populations, the incremental growth of networks, the bounds of human effort, and the relationship between socioeconomic output and personal interaction. According to these assumptions, cities are founded and grow primarily so that people can interact frequently and on a personal level. As demand for face time swells, cities expand, incrementally adding to the existing network. Eventually, those networks reach a limit, bounded by the amount of effort we are willing to expend to expand and maintain them. The greater the benefit of living in a city, the more effort we’re willing to expend to sustain it. Bettencourt’s final assumption may be his most astute—that cities aren’t just agglomerations of people, but also concentrations of social interactions.

The formulas Bettencourt derived could prove powerful. His most muscular equation, that which models city growth, identifies cities that punch above and below their weights. Others show how substandard transportation can hold a city back, or how transportation networks tend to grow incrementally (perhaps that’s why automobile sprawl seems so intractable). But his formulas also highlight some perils, like how energy loss in transportation increases superlinearly—the more you move, the more energy it takes to move something. In sum, they appear to build a solid theoretical framework by which further questions can be asked and hopefully answered.

Those of us who have been arguing for a science of cities¹ will find promise in Bettencourt’s work. It’s a strong first step, though I hesitate to declare victory and go home. It’s a theory based in data, but it’s still just a theory. Until it and other models are devised and tested experimentally, we won’t have a true, robust science of cities.

So what took us so long to get to this point? Why is it only now that we’re developing a true theory of the city? I have a couple theories. First, when many disciplines were delving into the world of theory—the 1940s through the 1970s—cities were thought to be relics of the past. Our newfound mobility had enabled us to leave the polluted, crime-ridden warrens behind, so why would we want to spend our time thinking about soon-to-be-obsolete cities? Only recently have we reevaluated urban areas, holding them in higher esteem than just a few decades ago. The other possibility is that cities are intensely complex, and that complexity is further complicated by the fact that we created it. Any time humanity is involved, the level of anxiety and detail ratchets up immensely. With cities and other human-based systems, it can be tricky to separate ourselves from the equations.

The current science of cities seems at about the state ecology was during the late 1960s and early 1970s. Then, overarching theories were new to the field, as they are now with cities. But because we’re already collecting so much data on cities—much more than is collected on the natural environment, I’d warrant—I expect urban science to evolve more rapidly. The gap will close, and perhaps someday the science of cities² will teach ecology a lesson or two.


  1. There has got to be a better term for this. Metropology? Sounds weird. Urbanology? Even weirder. Urbanistry? Whatever. We’ve got to find something better than “science of cities”. It just sounds lame, alliteration be damned.
  2. Seriously, the name already.

Source:

Bettencourt, Luís M. A. 2013. “The Origins of Scaling in Cities.” Science 340: 1438-1441. DOI: 10.1126/science.1235823

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Mo’ money, mo’ parks

Fujigaoka Park in Yokohama

Which came first, the park or the rich people?

It’s a poorly kept secret that real estate is more expensive near parks. They’re like magnets for wealth. But is that the whole story? Certainly wealthy people are attracted to parks—just look at many of the neighborhoods around Central Park in New York City. But what about new parks? Are they preferentially cited in wealthier neighborhoods, either because residents have more clout or developers are more willing to cede land to attract deep pockets?

Shinya Yasumoto and colleagues decided to tackle that question in Yokohama, Japan, a city of 3.7 million just outside of Tokyo. They tallied the number of parks that existed in 1988 and those that were opened from then until 2005. They also noted park size, accessibility, and neighborhood characteristics such as property values, resident incomes, housing characteristics, environmental quality, and other amenities, including schools and transit. They also indicated whether a park was set aside by the city or by a private developer.

What they found shouldn’t be surprising, but it should be cause for alarm. The city opened more parks than developers—556 compared with 472—and the total area of new city parks was substantially larger than those set aside by developer—1,702 hectares vs. 212 hectares. When the city opened a new park, it tended to be relatively equitable in terms of size and placement. Poor neighborhoods were almost as likely to receive a new park as richer ones. (Almost. The city wasn’t entirely immune from wealth’s influence; it did open slightly more parks in wealthier areas.)

Developers, on the other hand, clearly favored citing new parks in well-to-do neighborhoods. They added 117 hectares of parkland across 125 parks in the most affluent communities, but only 20 hectares across 59 parks in the least affluent. Furthermore, Yasumoto and colleagues note, the wealthiest areas had the best access to parks throughout the 18 year study.

The study was limited to Yokohama, one city in Japan. It’s possible that cities in other parts of the world don’t follow the same trend. But I’d be surprised if it didn’t. In hundreds of cities across thousands of years, parkland has been one of the many trappings of wealth.

Still, that doesn’t mean the situation is hopeless. Yasumoto and colleagues point out that a neighborhood’s demographic change lags behind park openings. So while it’s true that opening a new park will raise property values—potentially pushing out the poor—it won’t do so quickly enough to outweigh the benefits of new open space.

Source:

Yasumoto, Shinya, Andrew Jones, and Chihiro Shimizu. 2013. “Longitudinal trends in equity of park accessibility in Yokohama, Japan: An investigation of the role of causal mechanisms.” Working paper.

Photo by dakiny.

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Parkland per person in the United States

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An American in Tokyo

View from atop Atago Green Hills Forest Tower

Standing in awe of Tokyo is cliché. The city dazzles, sometimes quite literally with its bright signs, jumbo Jumbotrons, and sea of pulsing red lights stretching from here to the high-rise-filled horizon. But Tokyo is more than just hyperkinetic advertising and self-warming toilet seats. Here’s a shortlist of what makes Tokyo a magnificent city—and what it could do better—gleaned from my recent trip.

Peace and quiet

After a nearly 15 hour flight, I fell asleep as soon as my head hit the pillow. Less predictably, I wasn’t awoken at some ungodly hour by city noise disrupting my jet lag-addled body. Instead, I opened my eyes at 7:30 AM to the sounds of birds chirping in the nearby temple grounds. In the background, the city whispered.

The Scramble, Shibuya, Tokyo

Even at its most frantic—say, the scramble across Hachiko Square in Shibuya—Tokyo didn’t blare its metropolisness. It wasn’t for lack of traffic. Cars and trucks flowed on smooth streets and on elevated highways, the Shinkansen whisked along polished rails, and metro trains glided from station to station. Having lived in Chicago and Boston where trains rattle like the lungs of a septuagenarian chain smoker, the quiet subway surprised me the most. The Japanese understand the value of a little peace and quiet.¹ For that, I thank them.

Cleanliness

Japan has a reputation for cleanliness that’s well-earned. From the little piles of leaves carefully swept off the Meji Shrine’s gravel paths to the sparkling bathrooms in JR train stations, Japan is a tidy place. Surprisingly, it didn’t feel oppressive. Discarded gum still stains the sidewalk, and yes, I did stumble on the occasional bathroom that smelled like a bus stop. Overall, the country was pleasantly hygienic.

Buddhist graves

Chalk it up to their religion. For well over a thousand years, one of the majority religions in Japan has been Shinto,² and Shinto gods don’t like filth. I had always figured the Japanese obsession with cleanliness was a way to deal with the filth of modern cities. Imagine my surprise when it dawned on me that the Japanese have been like this for hundreds, perhaps thousands, of years. Given that cultural legacy, Japan’s cleanliness would be difficult to replicate in other countries without religious awakenings or authoritarian rule.³

Orderliness

Part of what makes Japan—and especially Tokyo—so clean is the fact that Japanese people like to follow rules. My friend joked that the Japanese like standing in line so much that he was tempted to start a line waiting for nothing and see who queued up behind him. Lines abound in Japan, especially in Tokyo. It certainly helps make the metropolis less chaotic and more manageable. Such orderliness can be refreshing, but there are times when it goes overboard. Like the trash of a pop-up ice cream shop, which was neatly stacked inside the bin.

Neatly stacked garbage, Tokyo

There’s orderliness, and then there are obsessive compulsions.

Shinkansen

Obsessive definitely applies to their rail system, but there it’s a virtue. I’ve said it here before, but we here in the U.S. are fools for not investing in high-speed rail. It’s truly a transformative technology. Trains depart Tokyo Station bound for Osaka—the Japanese equivalent of New York to Washington—every ten minutes or so from 6 AM to 9:20 PM. It completes the 343 mile (552 km) journey in 2 hours 25 minutes, and average delays on the line are measured in seconds, not minutes. The only high-speed line in the U.S. takes nearly 3 ours to make the 224 mile (360 km) run between New York and Washington.

700 series Shinkansen

Comparing those routes may be more apt than you first suspect. If you overlay Japan’s main islands with the East Coast, you’ll see that it stretches from the Florida Panhandle to New York’s border with Canada. In that space, Japan has about 130 million people, the U.S. about 112 million.

The Japanese aren’t any more accepting than we are of noisy train tracks, either. Both the U.S and Japan have their share of NIMBYs, or “not in my backyard” protesters. As a result, regulations limit noise from the Shinkansen to 70 dB in residential areas. Faced with this challenge, designers have streamlined the trains and engineers have polished the rails. As a result, on my two Hikari-service trains, we zipped through cities at shocking speeds.

Inside the train cars, things are modern, clean, and spacious. The only downsides I noticed were seats without power outlets (newer cars have them in every seat, older ones don’t) and first class Green Cars that smell like ashtrays. In a few years, I’m sure both will be taken care of.

It’s little wonder that that Japanese are extending the Shinkansen as far as they can, from subtropical Kagoshima in the south to Sapporo in the snowy north. Existing lines are being upgraded or replaced, drastically so in some cases. By 2027, JR Central expects to have maglevs zipping between Tokyo and Nagoya in about 40 minutes, and by 2045 from Tokyo to Osaka in a little over an hour. That’s nearly one and a half hours shorter than it takes today.

Parks

Hamarikyu Gardens

Partially by historical accident, Japanese cities have a wealth of parks. Temples and shrines are typically open to the public and offer a few minutes respite from city life. Former imperial grounds are also available for a nap or a stroll. Parks and other open spaces are not concentrated in one place, either, but spread throughout. The skyscrapers that dominate the horizon are the only reminder that you’re in a big city.

Architecture

Japanese architecture oscillates between inviting warmth and cool distance. Traditional buildings are all wood and coziness. Unfortunately, unless you were the emperor, that usually meant little interior light and cramped living space. But their detail is marvelous, from the careful use of natural materials to the expert joinery.

In Kyoto

Modern buildings can be both warm and cool. From the outside, they often present an austere, technocentric face. I was frequently overwhelmed by the sheer amount of metal and grey stone, a stark contrast with the glassiness of Western skyscrapers. But the aesthetic of modern Japanese buildings can switch from cool to warm the moment you walk in the door. Grey may dominate the facade, but yellow wood is everywhere inside.

Kyoto Station

For the most part, I’m not wild about the last few decades of Japanese architecture, with one exception: Roppongi Hills.

Roppongi Hills

That place is amazing. It’s level after level of hidden treasures—patios opening onto sweeping views, open-air plazas sheltered by expansive glass awnings, a massive outdoor performance space, and dozens of escalators nestled among towering skyscrapers. I spent half my time there outdoors and nearly all of that uncertain of where the actual ground was. But I was certain of one thing—Roppongi Hills feels like the future. You know, the one where people live in a planet-wide city where building on top of building obscures the terrain—and seedy underworld—beneath.

Just the beginning

Japan has a way of getting into your head. Perhaps it’s the contradictions of order and chaos, old and new, energy and passivity. Or maybe it’s the fact that no matter how long I may spend in the country, no matter how much I study its history and norms, I would never be considered culturally Japanese. Whatever it is, I know that someday I’ll return.


  1. You can even get a taste of it here in the U.S. Ever stood next to a Lexus at idle? Unlike many cars, you don’t hear a rumble but a muffled clacking. That’s the sound of the engine’s cams slapping against the valves. You can’t even hear the exhaust. That’s quiet.
  2. Buddhism was added in about the 600s, partially owing to the fact that Shinto gods don’t like the dead (they’re dirty, apparently) while Buddha doesn’t mind them. The two work pretty well together, and most religious Japanese are both Shinto and Buddhist.
  3. Cough, Singapore, cough.
  4. That’s practically a whisper—at my old place in Cambridge, I recorded over 80 dB as midday traffic roared by my open window (which was over 50 feet from the street).
  5. Coming from the U.S., that’s a very foreign concept.

We all want to live in small towns, and it’s killing cities

Downtown Northfield, MN

A bunch of economists and a blogger are trying to dissect the riddle of why metropolitan population density has fallen in the United States. Robert Shiller (yes, that Robert Shiller) seems to have unknowingly kicked off the whole thing when he wrote an essay a few weeks ago in which he said housing prices have actually been pretty stable when you adjust for inflation.

Bill McBride took issue with that, essentially saying that because land is scarce in cities, the value of the land (and the homes on it) should go up. Noah Smith didn’t quite agree with McBride, arguing that changes in transportation cost—everything from automobiles to telepresence—will counter the effects of population density over time, which is why house prices should remain flat. Paul Krugman jumped in and sided with Smith, mostly, citing the issue of declining metro population density across the United States.

Then Felix Salmon, the blogger, entered the picture. He wrote a post a few days ago laying out his solution to the riddle of why metro population density is declining. Rich people, he says, are moving to the city in larger numbers, and because they can afford more space, urban population densities are either holding steady or falling. That’s been pushing less wealthy people out to the suburbs and beyond. I’m skeptical that’s the real reason.

Most of the previous decade’s growth in the U.S. happened in the exurbs, those far flung outposts on the fringes of metro areas. There, populations rose by about 5 percent, much higher than the zero to 2 percent elsewhere throughout metro areas, including low-density but closer-in suburbs. People forgoing suburbs for the exurbs—that’s a nuance of the statistic that makes me question Salmon. If people are being driven out of the city because of high rents, then the suburbs should be growing swiftly, too. But they’re not—at least not as much as the exurbs.

Rather than reacting to what the rich are doing in the city, I think it’s more the result of how most of the rest of us would like to live. The exurbs are closer, by many measures, to the small town American ideal than the city or even the suburbs. Exurbs have single-family homes, big lots, wide streets, and a nearby countryside. The city doesn’t have that, and many suburbs don’t anymore, either—as cities swell, they’re becoming indistinguishable from the city. The exurbs are the new suburbs.

Krugman tries to drive home his point, saying, “the average American lives in a quite densely populated neighborhood, with more than 5000 people per square mile.” As such, he says, “real” America isn’t a small town, but rather something like metropolitan Baltimore. By pure statistics, he’s right. But that doesn’t necessarily mean the U.S. is a country trending toward Baltimore. A statistical snapshot can’t outweigh decades of cultural legacy. Most Americans may live like Baltimoreans, but do they want to?

Our cultural tendencies suggest we don’t. As long as the American ideal is to live in a small town—which to many people¹ means big yards, small downtowns, and concomitant low population densities—then that’s where we’re heading as a nation. If cities are to succeed, maybe they need to look to small towns for inspiration. Not the low densities—it wouldn’t be much of a city, then—but the more abstract qualities that draw people to them.


  1. Not necessarily me, though that’s a post for another time.

Photo by Northfielder.

Related posts:

Town, section, range, and the transportation psychology of a nation

How population density affected the 2012 presidential election

How far should you live from work?

More reasons to stop putting trees on skyscrapers

Bosco Verticale

Robert Krulwich, disagreeing with me:

Two residential towers, dense with trees, will have their official opening later this year in downtown Milan, Italy, near the Porta Garibaldi railroad station. (The image is not a photograph, but an architect’s rendering. The towers are built and the trees are going in right now.) I love this. I think these towers are gorgeous. Milan is a very polluted town; these trees will cleanse the air, pumping out oxygen and greening the cityscape. I think cities one day could look like mountain vistas; I’m enthralled.

But I am not Tim De Chant, tree lover, blogger, critic, who says this won’t work. All these trees, he thinks, are about to be dead. He recently posted an essay on his Per Square Mile blog, aimed at architects. He called it, “Can we please stop drawing trees on top of skyscrapers?” He thinks builders know squat about trees. I hope he’s wrong.

I know I seem like Buzz Killington to a lot of architects—and non-architects, Krulwich included—but that wasn’t my point…entirely. To me, trees atop buildings have become an architectural crutch, a way to make your building feel sustainable without necessarily being so. And that’s a charitable assessment. Here’s how I really feel—trees on skyscrapers are a distraction from rampant development and deforestation. They’re trees for the rich and no one else. They’re the soma in architecture’s brave new world of “sustainable” development.

In reality, trees on skyscrapers will likely be anything but sustainable. Structures built to support trees need to be over-engineered compared with their abiotic equivalents—trees are heavy, so is dirt (multiply so when wet), and so are watering systems required to keep them alive. If those trees are to have a chance on these windy precipices, their planters had better be deep, which further compounds problems raised in the previous sentence. A skyscraper that’s built to support trees will require more concrete, more steel, more of anything structural. That’s a lot of carbon, not to mention other resources, spent simply hoisting vegetation dozens of stories up, probably more than will ever be recouped in the trees’ lifetimes.

Bosco Verticale, the oft, and often only, cited example of a tower to be built with trees on top, is expected to cost $85 million. Stefano Boeri, the architect, estimates adding trees to the design pushed up construction costs about 5 percent. (No word on maintenance costs.) Whether that’s true or not, we’ll have to take his word for it. If we do, that means they will spend $4.25 million to put 2.5 acres—one hectare—of forest onto the side of a building.

Now, let’s say we take that money and resuscitate the region’s natural habitat.¹ Average costs run about $500 per acre for reforestation in U.S. national forests, with a top end of about $2,000 per acre. Let’s assume the worst. That means that with $4.25 million, you could restore 2,125 acres, or about 860 hectares, of forest. That’s 860 times more forest than is plastered on the side of Bosco Verticale. At the least. If restoration costs come in at the low end, about $200 per acre, it could be as high as 8,600 times more.

Then there’s the ecological value of each. Bosco Verticale will be home to a few birds (most of which will live in the city regardless) and some invertebrates, but not much else. It’ll also require massive human inputs—water, fertilizer, tending, and replacement. I covered the first of those three in my previous essay, so I’ll just elaborate on the last point here, replacement. Let’s say trees on a skyscraper will live for an average of 20 years—a generous assumption given that more than 50 percent of street trees, which are exposed to more benign conditions, die after just 10 years—what will we have gained? A skyscraper that needs an overhaul every 20 years.

A real forest, on the other hand, can replace itself. It can also support hundreds, even thousands of species, even in the middle of the city. A survey of the 315-hectare Central Park, for example, found over 800 species. Near Milan, at Parco Regionale di Montevecchia e della Valle del Curone, there nearly 1,000 known species on it’s 2,350 hectares. Biodiversity is just one measure. These forests also purify water, maintain nutrient cycles, and don’t require much in the way of maintenance (if any).

Here’s an alternate plan: Instead of planting trees on buildings, let’s focus on preserving and restoring places that already have, or desperately need, trees. Boeri and I agree on the importance of the latter. Bosco Verticale is the first stage of Boeri’s larger plan, one that includes preservation and restoration of existing land.² Bravo. It’s clear that Boeri understands the big picture, that to make a truly sustainable city, you have to incorporate ecosystem function on a broad scale.

We still disagree on the value of trees on skyscrapers: he, and Krulwich, see them as an inspiration; I see them as a distraction and potential liability—what if the Bosco Verticale becomes a brown eyesore, turning people off to his larger vision? I’d love it if Bosco Verticale and other proposed arboreal skyscrapers were sustainable and successful.³ Who wouldn’t want to live in a city full of tree towers? But I just can’t make a case for it. Plant physiology tells me that the trees, if they do survive, will require constant and costly maintenance throughout their short, brutal lives. Finance tells me that the money required to afforest a building would be more effectively used for restoration and preservation. And my gut tells me there are more equitable ways to give people trees, not just to those who can afford it.


  1. You could also plant street trees or reserve more land for parks, both laudable and equitable uses.
  2. Among the proposals is a greenbelt around the city. They’ll be great parks, but won’t do much to contain the city.
  3. Really, Robert, I do!

Sources:

Roman, Lara. 2006. Trends in street tree survival, Philadelphia, PA. Master’s thesis.

Gorte, Ross W. 2009. U.S. Tree Planting for Carbon Sequestration. Congressional Research Service R40562.

Illustration of Bosco Verticale.

Related posts:

Can we please stop drawing trees on top of skyscrapers?

Urban trees reveal income inequality

Income inequality, as seen from space

Can you tell urban from rural?

If you were given a section of a map, could you tell if was from a city or the countryside? The answer to that question may be trickier than you expect. I pondered this a year and a half ago when I wrote, “ ‘countryside’ is inherently interpretable term, one that depends more on how the land is used than it does on population density.”

It first struck me when I was traveling around Taiwan. There, the distinction between the rural and urban areas wasn’t always apparent to my Western eyes. The same can be true with maps. Distinguishing between urban and rural depends as much on geographic and cultural contexts as it does on visual cues like road networks.

Can you tell which is which?

The following maps are road networks from a variety of locations around the globe. Guess which are cities and which are rural areas. All maps are drawn to the same scale.

1.

2.

3.

4.

5.

6.

7.

From top to bottom: 1. city (Denver) 2. countryside (Japan) 3. city (New York City) 4. city (Houston) 5. countryside (Taiwan) 6. city (Los Angeles) 7. countryside (Wisconsin)

Related posts:

What do we mean by “rural”?

Income inequality, as seen from space

If the world’s population lived like…