Tag Archives: Density

A universal theory of cities

CC Image from lopolis

CC Image from lopolis

Last week, the New York Times Magazine featured a lengthy piece from Jonah Lehrer about two physicists who have formulated a sort of universal law for urban living.  The single biggest determinant of urban performance is size – increasingly large agglomerations offer economies of scale – people who live and work there are more productive, more creative, etc.  The physicists (Geoffrey West and Luis Bettencourt) summarize their main conclusions:

Three main characteristics vary systematically with population. One, the space required per capita shrinks, thanks to denser settlement and a more intense use of infrastructure. Two, the pace of all socioeconomic activity accelerates, leading to higher productivity. And three, economic and social activities diversify and become more interdependent, resulting in new forms of economic specialization and cultural expression.

We have recently shown that these general trends can be expressed as simple mathematical ‘laws’. For example, doubling the population of any city requires only about an 85% increase in infrastructure, whether that be total road surface, length of electrical cables, water pipes or number of petrol stations. This systematic 15% savings happens because, in general, creating and operating the same infrastructure at higher densities is more efficient, more economically viable, and often leads to higher-quality services and solutions that are impossible in smaller places.

These core economies of scale, positive feedback loops, and benefits of agglomeration are what lets cities be cities.  Now, we have some math behind it.

Some more quotes from the NYT Mag piece.

On urban systems:

There is something deeply strange about thinking of the metropolis in such abstract terms. We usually describe cities, after all, as local entities defined by geography and history. New Orleans isn’t a generic place of 336,644 people. It’s the bayou and Katrina and Cajun cuisine. New York isn’t just another city. It’s a former Dutch fur-trading settlement, the center of the finance industry and home to the Yankees. And yet, West insists, those facts are mere details, interesting anecdotes that don’t explain very much. The only way to really understand the city, West says, is to understand its deep structure, its defining patterns, which will show us whether a metropolis will flourish or fall apart. We can’t make our cities work better until we know how they work. And, West says, he knows how they work.

On similarities and dissimilarities to natural systems:

[T]he real purpose of cities, and the reason cities keep on growing, is their ability to create massive economies of scale, just as big animals do. After analyzing the first sets of city data — the physicists began with infrastructure and consumption statistics — they concluded that cities looked a lot like elephants. In city after city, the indicators of urban “metabolism,” like the number of gas stations or the total surface area of roads, showed that when a city doubles in size, it requires an increase in resources of only 85 percent.

…

What Bettencourt and West failed to appreciate, at least at first, was that the value of modern cities has little to do with energy efficiency. […] In essence, they arrive at the sensible conclusion that cities are valuable because they facilitate human interactions, as people crammed into a few square miles exchange ideas and start collaborations. “If you ask people why they move to the city, they always give the same reasons,” West says. “They’ve come to get a job or follow their friends or to be at the center of a scene. That’s why we pay the high rent. Cities are all about the people, not the infrastructure.”

On positive feedback loops:

West and Bettencourt refer to this phenomenon as “superlinear scaling,” which is a fancy way of describing the increased output of people living in big cities. When a superlinear equation is graphed, it looks like the start of a roller coaster, climbing into the sky. The steep slope emerges from the positive feedback loop of urban life — a growing city makes everyone in that city more productive, which encourages more people to move to the city, and so on. According to West, these superlinear patterns demonstrate why cities are one of the single most important inventions in human history. They are the idea, he says, that enabled our economic potential and unleashed our ingenuity. “When we started living in cities, we did something that had never happened before in the history of life,” West says. “We broke away from the equations of biology, all of which are sublinear. Every other creature gets slower as it gets bigger. That’s why the elephant plods along. But in cities, the opposite happens. As cities get bigger, everything starts accelerating. There is no equivalent for this in nature. It would be like finding an elephant that’s proportionally faster than a mouse.”

Scarcity is the check on this superlinear growth, and innovation is what breaks that check.

On counterpoints to these universal laws: Lehrer quotes suburbanist Joel Kotkin in his piece, with Kotkin arguing against this logic of density and economies of scale, citing Silicon Valley and the Research Triangle.  Kotkin is too focused on the traditional narrative of cities and suburbs, however.  Both of those examples are still agglomeration economies, just comprised in a different physical form. A ‘city’ here is also the total urban area, not the arbitrary political boundaries that Kotkin often hangs his hat on.

It’s also important to note that this kind of universal law sets the baseline for what’s to be expected of a city – certain places will under or over-perform.  That’s where the quality of a place comes in, in my estimation.

On qualitative measures: West and Bettencourt specifically avoid the qualitative, since they can’t measure it well with data.  It’s important to not set qualitative and quantitative measurements in opposition, however.  WNYC’s RadioLab delved into the qualitative aspects of what makes cities into cities back in October.  These different explanations of cities are not mutually exclusive.  Indeed, they are complimentary.

This discussion, both the qualitative and quantitative aspects of it, seem to further embrace the Three D’s of density, diversity, and design.  The question is then about how to assess each of those factors.  Given that each one of those factors can be defined expansively (diversity of people, of skills, of land use, of incomes, of languages, of cultures, etc) and not all of those varied elements can be effectively quantified, this only reinforces the co-dependence of both analytical methods.

On planning: Lehrer closes his piece with a note about the inherent messiness of cities – the “energized crowding”, to steal a phrase from Spiro Kostof.

Unlike companies, which are managed in a top-down fashion by a team of highly paid executives, cities are unruly places, largely immune to the desires of politicians and planners. “Think about how powerless a mayor is,” West says. “They can’t tell people where to live or what to do or who to talk to. Cities can’t be managed, and that’s what keeps them so vibrant. They’re just these insane masses of people, bumping into each other and maybe sharing an idea or two. It’s the freedom of the city that keeps it alive.”

One common misconception about planners and planning is that we seek to control everything.  Instead, I am more interested in this kind of messy interaction.  Planning is about facilitating those interactions, not about controlling them.  For that reason, I find this kind of research fascinating.

The entire piece is fantastic.  Read the whole thing.

Agglomeration, continued

Nike Agglomeration crop

More items of note on agglomeration:

From City Journal, the “Seven Pillars of Agglomeration.”

  1. Economies of scale in production
  2. Economies of scale in trade and transportation
  3. Falling transportation and communication costs
  4. Proximity with other firms in the same industry
  5. Advantages of diversity
  6. The quest for the center (of the industry)
  7. Buzz and bright lights

And, from The New Republic‘s Avenue blog, a visualization of those principles in action, looking at the athletic and outerwear industry in Portland, OR – from Pendleton (1889) to Nike (1978).

But the A&O cluster is also an interesting case study in cluster morphology and dynamics. Check out this cool genealogy map developed by sometime Metro Program author Heike Mayer of the University of Bern, for example. Meyer’s info-graphic shows well how the A&O cluster has grown over time and now epitomizes the frequent structure of highly dynamic clusters, which often find a small number of large foundation firms (in this case Nike, Adidas, and Columbia Sportswear) surrounded by a cloud of scores of smaller, more entrepreneurial firms. In Portland, hundreds of these small and sometimes tiny firms are now proliferating–driving growth, developing their own niches, and providing services to the bigs and larger new firms.

The accompanying infographic (full size image – PDF file) shows this phenomenon in action, and through time.  As noted, building on these existing clusters, taking advantage of these agglomerations is the smart approach to economic development:

All together, it’s a great example of how the best sort of economic development eschews chasing after firm relocations and other silver bullets and instead concentrates on “organic” growth that arises from local distinctiveness.

Agglomeration is about letting cities be cities.

Things that matter

Museo Guggenheim Bilbao - from La Tête Krançien

Museo Guggenheim Bilbao - from La Tête Krançien

Mammoth directs our attention to this post from LA Times architecture critic Christopher Hawthorne, talking about the systemic flaws of lists of the best buildings (and architecture criticism in general):

When Vanity Fair magazine recently released the results of a survey ranking the most significant pieces of architecture of the last 30 years — with Frank Gehry’s Guggenheim Museum in Bilbao, Spain, topping the list — the poll was met with more than a little grumbling. Some people griped about the many architects, including Richard Meier and Daniel Libeskind, who voted for their own work (talk about a vanity fair!); others noted that the average age of those polled, a group including architects, critics and academics, seemed to be pushing 70.

Mammoth also notes the tendency for architects to nominate their own buildings to the list – particularly the ones that don’t show up on any other lists.  Another criticism was the list’s complete whiff on any green architecture, spurring an alternative contest with an emphasis on sustainability.  Hawthorne delves into the more fundamental issue:

Asking voters to submit a list of single buildings necessarily produces results that give a skewed view of the way architecture — and more important, the way we think and write about it — has evolved in recent years.Among critics and architects alike, there has been a growing understanding that architecture is not just about stand-alone icons but is tied inextricably to real-estate speculation, urban planning, capital flows, ecology and various kinds of networks. Similarly, ambitious architecture criticism now means a good deal more than than simply writing about impressive new landmarks, green or not, produced by the world’s best-known firms […]

Maybe, in other words, the most important achievement in green architecture over the last 10 or 30 years is not a single building at all. Maybe it’s a collection of schools or linked parks or the group of advisors brought together by a young mayor somewhere. Maybe it’s a new kind of solar panel, a tax credit or a zoning change. Maybe it’s tough to hang a plaque on — or photograph for a magazine spread.

Emphasis is mine.  The same logic applies to the environmental benefits of urban density and city living, as opposed to just adding LEED certified buildings.   How about hanging that green award on a carbon tax or the elimination of parking minimums.

Intersection density & centrality

What is the best method to quantify what makes a place walkable?  The Journal of the American Planning Association recently published some powerful documentation from Robert Cervero and Reid Ewing on the value of pedestrian-oriented design (following up on yesterday’s links).  Grist has the article (hat tip to Planetizen), citing Laurence Aurbach’s PedShed blog – again, the “Three D’s” or urbanism emerge front and center – density, diversity, and design:

Their findings? Of all the built environment measurements, intersection density has the largest effect on walking — more than population density, distance to a store, distance to a transit stop, or jobs within one mile. Intersection density also has large effects on transit use and the amount of driving. The authors comment,

This is surprising, given the emphasis in the qualitative literature on density and diversity, and the relatively limited attention paid to design.

In other words, intersection density is the most important factor for walking and one of the most important factors for increasing transit use and reducing miles driven, but gets relatively little attention in research and in public policy.

In other words, the other two D’s (density and diversity) get more play than design.  Perhaps that’s because density and diversity (of land use, of people, of incomes, etc) were easier to quantify than something as seemingly subjective as design.

Intersection_Density

Kaid Benfield ties these principles to those angry about the ever expanding oil slick in the Gulf of Mexico, hitting on another theme of the research – location:

The study’s key conclusion is that destination accessibility is by far the most important land use factor in determining a household or person’s amount of driving.  To explain, ‘destination accessibility’ is a technical term that describes a given location’s distance from common trip destinations (and origins).  It almost always favors central locations within a region; the closer a house, neighborhood or office is to downtown, the better its accessibility and the lower its rate of driving.  The authors found that such locations can be almost as significant in reducing driving rates as other significant factors (e.g., neighborhood density, mixed land use, street design) combined.

The clear implication is that, to enable lifestyles with reduced driving, oil consumption and associated emissions, environmentalists should continue to stress opportunities for revitalization and redevelopment in centrally located neighborhoods.  As Ewing and Cervero put it:  ‘Almost any development in a central location is likely to generate less automobile travel than the best-designed, compact, mixed-use development in a remote location.’

Aurbach is quick to note the limitations of the study, but even with those this is an exciting quantification and potential metric for walkable and sustainable design.  It builds off the Jacobs legacy of ‘short blocks’ and adds some science behind recent GGW posts from Erik Bootsma and Daniel Narin on the variety and histories of street grids.  This kind of research lends weight to the anecdotal accounts of Portland’s small blocks resulting from the belief that corner lots were more valuable, as well as ideas of better utilization of alley space – such as this recent post from Richard Layman.

Changing suburbia

Some suburban items to share today:

Design: Infrastructurist takes a look at the problem of culs-de-sac (which I believe is the proper plural of cul de sac).

cul-de-sacs

Commenters take note of some serious issues with this particular study, but the general point still stands – culs de sac remove key links from the street network, requiring longer and more circuitous routes to get to the same destinations.  Developments of these kind of street patterns are no small part of America’s long history of vehicle miles traveled increasing far faster than the rate of population growth.

Diversity: The Washington Post has an article on the changing face of suburbia – more socially and economically diverse, and dealing with new sets of problems that many of these communities have never had to deal with before:

Demographers at Brookings say suburbs are developing many of the same problems and attractions that are more typically associated with cities. And cities, in turn, have been drawing more residents who are young and affluent, so the traditional income gap between wealthier suburbs and more diverse cities narrowed slightly.

“The decade brought many cities and suburbs still closer together along a series of social, demographic and economic dimensions,” said the report, titled “State of Metropolitan America.”

The other substantive point is about how Americans perceive their surroundings (urban, suburban, rural) compared to how their city and their urban economy actually functions:

The report outlines a decade in which several demographic milestones were passed as the nation’s population topped 300 million midway through. About two-thirds of Americans live in the nation’s 100 largest metropolitan areas, virtually all regions with populations of 500,000 or more.

“We think we’re a small-town nation,” Berube said. “But small towns exist because they’re connected to something bigger, which allows residents to make a living.”

Density: Ryan Avent has long marked the economic benefits of density and the nature of urban agglomerations, but he has an interesting point on the marginal benefits of added density, noting that modest increases in the less dense suburbs could have a troubling impact, while modest increases in the already dense core, already designed at a walkable scale, would have serious benefits for local retail.

So let’s think about the effects of doubling density in Fairfax and the District. Now on the one hand, the benefits to doubling density in Fairfax are likely to be larger than those in Washington for reasons of scale alone — in the Fairfax example, more people are added. That makes for a deeper labour pool, a larger skills base, and so on. On the other hand, Fairfax density is likely to be less effective density. Fairfax is built in a fairly standard, suburban way. It’s not built at a walkable scale, the road system is arterial rather than gridded, transit options are limited, and so on. Doubling density, absent major infrastructure improvements, might actually reduce the metropolitan access of Fairfax residents.

Not so in the District. Yes, with more people roads, buses, and the Metro would be more heavily taxed. At the same time, every neighborhood would become individually more convenient. Brookland is fairly low density for a District neighborhood, but it’s basically built to be walkable. Were density in Brookland to double, the retail and commercial options within easy walking distance of Brookland residents would more than double.

The problem with doubling the density in a place like Fairfax County, aside from the infrastructure issues that Ryan highlights, is that you’d end up with a place that’s stuck in the no-man’s land of density – too dense for the auto-oriented infrastructure to function smoothly, but not dense enough to really tap into the critical mass and benefits of walkable urban places.

Weekend Reading

CC image from sabeth718

CC image from sabeth718

There’s a whole host of good stuff out there this weekend, covering the economy, smart growth, transit, high speed rail, and more:

Smart growth is nothing to fear: Roger Lewis aims to quiet the fears of Washington Post readers:

In fact, as new long-range plans are implemented in the coming decades, your property’s value will probably go up, your way of life and neighborhood character will be enhanced, and traffic congestion will not worsen. Indeed, it may ease. Also remember that such plans primarily serve future generations.

Optimism is justified. Stable, low-density residential neighborhoods and subdivisions will remain untouched. Transportation network plans do not depend on routing future traffic through subdivisions and local residential streets, many of which are loops and cul-de-sacs. And redeveloped areas actually will provide new, desirable conveniences for residents able to walk or bike to buy a quart of milk or sip coffee in a cafe.

Daniel Gross puts that into a larger context: Complete with quotes from Richard Florida, Mr. Gross looks to optimistic visions of the future and the chance to re-shape our economy, using the pending economic rebound to re-shape things – putting those kinds of smart growth plans into action:

So what will our new economy look like once the smoke finally clears? There will likely be fewer McMansions with four-car garages and more well-insulated homes, fewer Hummers and more Chevy Volts, less proprietary trading and more productivity-enhancing software, less debt and more capital, more exported goods and less imported energy. Most significantly, there will be new commercial infrastructures and industrial ecosystems that incubate and propel growth—much as the Internet did in the 1990s.

Not everyone is so optimistic: Reihan Salam at The Daily Beast isn’t nearly as optimistic about our economic prospects, despite the good intentions and aspirations of folks like Roger Lewis.

But one could just as easily argue that we’ve been furiously spending taxpayer dollars propping up the McMansion-and-Hummer economy. To protect homeowners, we’ve launched an extraordinary series of interventions designed to buttress housing prices, an approach that effectively transfers wealth from those who rent to those who own. Collapsing housing prices could prove a boon for less-affluent households or cautious investors who were reluctant to buy at the top of the market. That can’t help unless we accept that housing prices can and should collapse, even if that hurts key constituencies in the short term. And the same goes for efforts to keep the domestic automotive industry on life support.

So, are we in a moment of change or not?  The point about renters and owners is well taken, it reminds me of plenty of discussion around tax day about the perils of the mortgage interest deduction.

Beyond these big, national-level policy questions, there’s plenty of room to debate the local impact.  Housing Complex notes that DC has lots of jobs (relatively) and high rents, circling back to the notion that the ability to change things won’t be uniform across the nation.  Places like DC are positioned well to make the transformation – provided the Federal framework enables these kinds of changes.

On that note, Aaron Renn looks at a potential city-friendly federal policy framework, emphasizing talent, innovation, and connection – looking at policy areas of transportation, housing, the environment, and immigration.  Perhaps the key takeaway is the requirement of flexibility – many of today’s problems stem from federal policies that are too rigid to be of much use in urban environments.

Density discussions: Density is good for cities.  It’s also often misunderstood and feared – see Roger Lewis’ calming of fears regarding smart growth.  A few posts on the subject:

  • Yonah Freemark questions whether streetcar suburb densities are enough to get real urbanism and transit use.
  • Aaron Renn asks if density is overrated for smaller cities, as they can still compete without it, taking advantage of highways and cars that work well at lower densities.
  • Cap’n Transit criticizes both thoughts, emphasizing the bigger picture about why we want to encourage urbanism and transit use in the first place – arguing that Renn’s rationalization isn’t helpful in the long run.

Miscellany:

Economists for cities, density

CC image from urbanfeel on flickr

CC image from urbanfeel on flickr

Ed Glaeser, professor of economics at Harvard, chimes in on cities, density, and their economic value on the Economix blog:

But now humanity is marked more by concentration than by spread. In 2007, one-half of the world’s population became officially urban. One-third of Americans inhabit just 16 large metropolitan areas, which collectively use only a tiny fraction of the country’s land mass…

Understanding the appeal of proximity — the economic advantages of agglomeration — helps make sense of the past and future of cities.   If people still clustered together primarily to reduce the costs of moving manufactured goods, then cities would become increasingly irrelevant as transportation costs continue to decline.

If cities serve, as I believe, primarily, to connect people and enable them to learn from one another, than an increasingly information-intensive economy will only make urban density more valuable.

Glaeser highlights several conclusions – including a key one that density increases productivity. Ryan Avent has harped on this before.  Any way you slice it, the end idea is that cities are the intellectual and economic hubs of our country.

Improvements in transportation and communication costs made it cost-effective to manufacture in low-cost areas, which led to the decline of older industrial cities like Detroit. But those same changes also increased the returns to innovation, and the free flow of ideas in cities make them natural hubs of innovation. Since the death of distance increased the scope for new innovation, idea-intensive innovating cities were helped by the same forces that hurt goods-producing cities.

Humanity is a social species and our greatest gift is our ability to learn from one another. Cities thrive by enabling that learning, and they have become only more important as knowledge has become more valuable. Understanding what makes cities work is more important than ever.

In order to avoid alienating groups on political grounds, it’s worth noting that we’re talking about cities, broadly defined.   Just as the focus on urban, walkable places is an urban design distinction rather than a political one, the benefits of urban agglomerations are regional.  Design matters, of course – I’d be curious to see if an economist could measure if economic benefits of agglomeration can be attributed to any other characteristics other than density.

Defining sprawl

Rural Sprawl

When reading discussions about sprawl, one thing often becomes painfully clear – no one quite knows exactly how to define sprawl.  Defining sprawl probably bears some similarities to Supreme Court Justice Potter Stewart’s famous definition of obscene pornography – “I know it when I see it.”   Indeed, when we’re talking about a qualitative measure of the built environment, it’s not particularly easy to come up with an authoritative definition.

First, I’d point out that when I talk about sprawl (as noted above), I’m talking about the built environment.   Too often, discussions get framed in polar terms – urbanity vs. sprawl, inner cities vs. suburbs, etc.  I don’t find any of these dichotomies are particularly useful in describing the built environment – not only do they not fit the complex patterns of development, but associations with inner cities or suburbs are too often charged with relatively unrelated social characteristics.

Sprawl is also not synonymous with suburbia, nor is it equal to a simple outward growth of an urban area.  Sprawl has four key characteristics, each of which are inter-related:

Density – sprawling development is typically low density, but land use patterns often prevent the positive externalities of density from accruing.

Segregation of land use – separating land uses into different parcels is both a product of lower densities and auto-centric design…

Auto-centrism – what distinguishes sprawl from just suburban growth is the focus on the automobile as the only real means of transportation.

Outward growth – the connotation of sprawling out, away from the city is only one factor of urban sprawl.  Sprawl often involves ‘leapfrog’ development away from the periphery.

Except for the outward growth, each of those points could be considered to be the opposite end of the spectrum for the 3D’s of Density, Diversity, and Design.

Cap’n Transit hits on some of these points – noting that all suburbs are not sprawl (and many of today’s urban core neighborhoods were once considered suburban development on the periphery):

Drum’s question actually shows that a lot of urban history is being forgotten. Most “urban cores” started out as bedroom communities. Greenwich Village, Brooklyn Heights, Long Island City and the Bronx were suburbs once. Hudson County, the part of New Jersey across the river from Manhattan, includes the four densest towns in the US, according to the 2000 census: Guttenberg, West New York, Union City and Hoboken. I’ve long thought that New York should just annex Hudson County as the fifth borough and be done with it.

If those are too “urban core” for you, consider these “streetcar suburbs” of Westchester County, all of whom have high-rise apartments walking distance from a commuter rail station, downtown shops and a supermarket: Scarsdale, where Garth Road is lined with seven- to ten-story luxury co-ops; Bronxville; the Fleetwood neighborhood of Mount Vernon; New Rochelle; Larchmont; and many more.

Oh, and for Jarrett, these Westchester suburbs all have twice-hourly trains to Grand Central Station six days a week, and hourly service on Sundays.

Most of these buildings were built years ago, between 1920 and 1960; for more recent dense suburb-building, see the claims for various DC suburbs. New Rochelle has also seen some recent high-rise transit-oriented development.

A sprawling synopsis

Image from Dean Terry on flickr

Image from Dean Terry on flickr

There’s been a great back and forth across the blogosphere in the past few days on sprawl, zoning, land use regulation, and market forces.  A brief synopsis and chronology:

3/18, 8:47 am – Randal O’Toole – complete with terms like ‘poppycock’ that completely fit the mental image I have of him:

This is all balderdash and poppycock. People who believe it should get their noses out of Kunstler’s biased diatribes and look at some real data and see how zoning actually worked before it was hijacked by authoritarian urban planners. It doesn’t take much to show that areas without any zoning or regulation will — if developed today — end up as what planners call “sprawl.” Until recently, all that zoning has done has been to affirm the kind of development that people want.

3/18, 12:58 pm – Matt Yglesias -Yglesias argues that our sprawling environment isn’t a manifestation of market demand:

I’m not personally interested in debating the “smart growth” slogan. My point is that from a policy point of view excessive regulation of land use in already developed areas is bad for the economy and for the environment. And to be specific and clear about this, I don’t think the problem is “libertarian” hypocrites per se, the problem is specifically John Stossel and Randall O’Toole who are stridently opposed to anti-sprawl regulations but seem totally uninterested in sprawl-promoting ones.

3/18, 7:28 pm – Kevin Drum – we have exclusionary zoning regulations because people really, really want them.

I need to be clear here: I’m neither praising nor condemning this, just describing how things are. To get an idea of how strongly people feel about this, you really need to come live in a suburb for a while. But failing that, consider the balance of power here. Corporations would like to be able to build wherever and whatever they want. Wealthy land developers would like to be able to build wherever and whatever they want. And local governments hate single-family neighborhoods because they’re a net tax loss: they cost more in services than they return in property tax remittances. And yet, even with corporations, wealthy developers, and local governments all on one side, suburban zoning is ubiquitous. This is a triumvirate that, under normal circumstances, could get practically anything they wanted, but in this case it’s not even a close fight. Suburban residents have them completely overwhelmed.

3/19, 11:18 am – Ryan Avent – zoning is about exclusion and control – it is a manifestation of NIMBY attitudes and not one of popularity:

So people build where it’s easiest and cheapest to build, which is on the urban fringe. And walkability is difficult to build on the urban fringe because transportation will be overwhelmingly auto-oriented (the fringe being distant from employment and retail centers and unserved by transit). So you get acres of tract housing, which subsequently become filled with people, who then do what homeowners everywhere in the country do, which is try to exclude new people from moving in to their neighborhood. And development then moves further outward.

But the notion that suburban sprawl wins out simply because it is so popular is belied by housing cost data. People live where they can afford to live, and if they can’t afford to live in a walkable area, then they’ll opt to live in sprawl rather than go homeless. And once there they’ll act to defend their investment by fighting development projects that may have unpredictable impacts on the value of nearby single-family homes.

3/19, 2:28 pm – Matt Yglesias – exclusion is a general phenomenon (see NIMBYism), not just suited for suburbia and sprawling places.

It’s true that the problem of overly restrictive land-use rules is in large part a problem of voter-preference. But it’s not a problem of voter-preference for sprawl per se. It’s a general problem of homeowner eagerness to exclude outsiders. It’s politically difficult to build dense infill development in Washington, DC and that’s not because DC residents want to live in sprawling areas or because DC residents approve of sprawl as a phenomenon. It’s a mixture of selfishness, misunderstanding, and poor institutional design. As Ben Adler reminds us, surveys indicate that about a third of Americans would like to live in walkable urban areas but less than 10 percent of the country’s dwelling units are in areas that fit the bill. That’s why houses in walkable central cities (Manhattan) and walkable suburbs (near Metro in Arlington Country, VA for example) are so expensive.

3/19, 2:45 pm – Kevin Drum – No, people like sprawl.  Honestly.

Sure, exclusion is part of the dynamic here, but by far the bigger part of it is that lots and lots of people actively like living in non-dense developments. Seriously: they really do. It’s not a trick. So they vote with their feet and move to the suburbs and then vote with their ballots to keep big-city living at bay. Given an ideal world, of course, they’d love to have a nice 3,000 square foot house with a big yard right in the middle of Manhattan, but one way or another, they want that house.

3/19, 7:07 pm – Ryan Avent – Price data shows a clear preference to walkable, urban places.  Moreover, the density that creates that value also raises productivity – urban walkability is expensive for a reason, the positive externalities of urban lifestyles compound on one another. Suburban residents, however, fight added density and walkability because they never see the benefits of those positive feedback loops:

Say New York started selectively zoning parts of Manhattan for single-family home only use. The first few folks to buy would have a glorious time of things. But as additional people moved in, density would fall. Declining density would ultimately reduce the walkability of Manhattan, but perhaps more importantly, it would lead to a deterioration of the positive externalities associated with the high level of density. Density raises productivity and wages (see this, or this). And because of this benefit and positive spillovers associated with density, we find increasing returns to scale in cities. In many cases, the addition of another person to a dense area increases the return to others of locating in that area. And things work in the opposite direction as populations decline. The fact that residents of dense cities don’t internalize these benefits is one of the reasons they fight new development.

Low density suburban development eats up a lot of land while contributing relatively little to the positive urban externalities associated with density. And meanwhile, the combination of auto-centricity of suburbs with the inability of governments to correctly price congestion externalities means that suburbanites end up limiting urban growth in an economically unfortunate manner by reducing potential wages and raising the real cost of commuting into (and therefore within) the city. One reason sprawl is attractive is that the people living in it aren’t facing the true cost of their decision to live in sprawl (and this is without ever bringing carbon into the mix).

All in all, some very interesting points on sprawl, economics, design, land use, and so on.  I wanted to aggregate these posts here as a baseline for more discussion – because this post is already long enough.  I didn’t even get a chance to touch on the discussions of High Speed Rail and sprawl – with posts from the CA HSR blog, as well as the Transport Politic.

Perceptions of density often miss the mark

Photo from cacophony76.

Photo from cacophony76.

Density is one of the most important elements of any city, but also one of the most misunderstood.

However, the density of a site is often not what it initially seems – people will key on things like height, design, maintenance, and context rather than actually looking at what density means to them.  It’s a natural, emotional reaction – but often misses the underpinning reality.  Educating people on what density looks like is vitally important, as density is a crucial element of sustainable, urban places.

In Washington, DC, like many other places, people often have a visceral reaction against density.  They assume more density means taller buildings in a low-rise city, but that need not be the case.  These fears of density are not unfounded, however.  Complaints about density often reveal other concerns, such as traffic congestion or design.

Dan Zack is a planner for Redwood City, CA.  He recently gave a presentation out in California which included the following ‘quiz,’ asking attendees to quickly assess how dense a building or development is based on a passing glance at a photograph of the site.  The clip is just shy of 12 minutes long.  Take a look and see how accurate your perceptions of density are:

Density often gives rise to fears from neighbors about traffic congestion, crime, environmental quality, and many other factors.  Outside the immediate community, people scream about social engineering and forcing people to live in dense environments, despite the fact that increased density is a product of market forces and substantial pent-up demand.  Mr. Zack’s quiz shows how density is often not what it seems.

Height, for example, is only one factor in density.  Paris is almost uniformly low-rise in nature, yet has extremely high densities.  For DC, the takeaway message is that the city can continue to grow and add density without fundamentally altering the low-rise nature of the city.  As DC continues to grow, adding more housing supply will be of vital importance.  More households can also help certain areas of the city reach a critical mass of retail buying power, enabling stores and restaurants to survive and thrive.

Just as height is only a factor in density, density itself is only a factor in the overall health of a city.  Put in simple terms, a city needs the Three D’s – Density, Diversity, and Design – to thrive.  As Mr. Zack’s quiz shows, diversity (of housing sizes, price points, neighborhoods) and design all factor in to how we perceive density.  Each of the Three D’s is deeply interwoven with the others, and touch on all urban issues, from transportation to affordable housing.

Emphasizing the need for density at this juncture is important, as well.  Cities are not static environments.  They change a great deal over time.  In the next 25 years, approximately 75% of the American built environment will either be renovated or built anew. Even accounting for a lull in demand from the Great Recession, American cities are in for a great deal of change.

The entirety of Mr. Zack’s presentation is well worth watching, and can be found below.  His presentation is about 50 minutes long, and includes the ‘quiz’ clip above.  In the remainder, he discusses at length all of the companion issues that need to be dealt with in addition to adding density, such as design, parking, transit, and walkability.

Cross-posted at Greater Greater Washington