Tag Archives: 3Ds

Density – a vision for an urban America

The world is urbanizing. But is it doing so in a truly urban fashion, or is it merely a way of noting that ‘urban’ can be defined as ‘not rural?’

This is one of the concerns Vishaan Chakrabarti brings up in his discussions of ‘hyperdensity’ and his book making the case for a truly urban future: market-driven, transit-supportive, and more dense and urban than what we have today. Chakrabarti notes that this isn’t meant to denigrate suburbanism, but to merely level the competitive playing field and to stop direct subsidy of suburbanization.

ArchDaily links to a video of Chakrabarti speaking before a panel of big names in architecture and academia at Columbia University. They summarize as follows:

Through the compelling representation of statistics, Chakrabarti makes a concise case for the benefits of investing efforts in a development strategy that is based on dense cities. By identifying issues in modern infrastructures, current city planning policies, and paradigms within the design and construction fields, he paints a new urban landscape.

And the video:

[youtube http://youtu.be/ZBC_Pa1a6bc]

In the panel discussion, Bernard Tschumi notes that the ideas Chakrabarti presents are not new; to which Chakrabarti asks rhetorically, “then why are we in this mess?”

Speed, urban transportation and geometry heuristics

Following up on this previous post, noting that “transport is mostly a real estate problem” – a few quick heuristics on cities, speed, and space:

Comparison of population/employee density and street area per person. Image from NYU Urbanization Project.

Regarding speed:

Speed requires space; faster travel occupies a larger area than slower travel.

Speed alters our perception of space. Faster travel makes large things seem smaller (hat tip to this post from GGW for the links). The properties of the space affect how we use it and what we percieve it to be; wider roadways within streets get used for faster travel.

Regardless of speed, cars require large spaces relative to their capacity. Even when parked (v = 0), cars require lots of space. By extension, building cities around requires a completely different spatial footprint.

Regarding space:

There is a strong tendency for cities to devote about 25% of their land to streets. Street networks are for mobility, but also for access to land. Devoting too much land to streets is wasteful; too little makes it difficult to unlock the value of the land within a city.

Intersection density correlates with walkability and connectivity; wider instersection spacing correlates with the higher speed travel of cars.

Consider the relationship between the density of the network (intersection density), the tendency to use ~25% of land for streets (regardless of the density of the place), and street width on the kind of transportation.

Simply requiring some minimum intersection density for new developments via a code will still be subject to ‘gaming’ and open to unintended consequences.

Street networks are sticky and tend not to change once established; the cities that grow around them are path-dependent. However, transport networks can be layered – subways travel fast, require space and grade-separation, but deliver passengers to the street grid as pedestrians; just as freeways are layered above/below streets and deliver high volumes of cars to local streets.

While the physical space allocated to streets tends not to change, the use of that space can change a great deal over time.

“Hyperdensity” and providing cities the room to grow

CC image from Alan Grinberg

The first thing crossing my mind when reading Vishann Chakrabarti’s piece in Design Observer (Building Hyperdensity and Civic Delight) was: what the hell is ‘hyperdensity?’ Thankfully, Chakrabarti answers that question in the first paragraph: “density sufficient to support subways.”

The second thing to cross my mind was why he would frame a reasonable kind of urbanism – transit-supportive density – in such extreme terms? Chakrabarti is a principal at SHoP Architects and a professor at Columbia. Hearing someone in that position praise the very real benefits of density isn’t surprising, though the framing of the issue as ‘hyper’-anything seems naive in the face of neighborhood opposition to even minor changes like the allowance of accessory dwelling units.

Contrast Chakrabarti’s position to that of Brent Toderian. Toderian, formerly the chief planner in Vancouver, BC, is a veteran of many contentious civic battles over development and density. His calling card is to focus on mitigating any possible downside of density, re-branding the ideal as ‘density done well.’ Leaving aside any substantive differences between Toderian and Chakrabarti, the difference in framing is significant. Both praise the benefits of density for an urban economy, for climate change, and for city life; both agree that dense environments demand good design to address the challenges that density can present. Yet, Toderian emphasizes that it can be ‘done well’ (implying that it currently isn’t done well) while Chakrabarti emphasizes the need for more density (implying that we don’t currently have – or allow – enough of it).

Chakrabarti isn’t satisfied with the small-scale focus from current planners, and embraces the general focus of the econourbanists:

Today the global economy demands that we embrace large buildings not just for housing but also for many modern office functions; yet many planning professionals remain fixated on smaller-scale development. They tend to ignore that height limitations have held back the Parisian economy in comparison to the forward-looking redevelopment of London, both at Canary Wharf and within its city center, which is now marked by a series of glistening and respectful new towers by Norman Foster, Richard Rogers and Renzo Piano. There is, in fact, a marked correlation between those European cities that have allowed skyscrapers and those that have successful economies.

Chakrabarti also mentions the challenges of building denser cities in today’s regulatory environment of zoning codes and lengthy reviews, risk-aversion from incumbent residents and landowners, and the feasibility of adding new infill development into established neighborhoods without fundamentally altering their character.

Perhaps the single most compelling reason to act is the growing challenges of affordability. This Wall Street Journal article highlights the challenges in New York, quoting Professor Chakrabarti extensively:

In the coming decades, New York could confront a problem many cities would love to have: too many people and nowhere to put them.

The city is expected to add one million more residents by 2040, but there likely won’t be room for hundreds of thousands of them unless a small city of new housing is built, according to a report by a Columbia University think tank.

“What surprised me most was the scale of the problem,” Mr. Chakrabarti said. “It’s a clarion call that we don’t have enough housing.”

At the same time, plenty of other publications about affordability challenges in cities around the world do not even mention the restrictions on and challenges to add housing supply. At the same time, the fact that many American cities used to have more people residing in the same area will lead them to believe that the city can accomodate more people without exanding the city’s building stock. The reality is that those older population figures included larger household sizes and fail to account for housing stock lost to commercial development from expanding downtowns. Payton Chung looks into these claims for DC:

These conditions were common in District homes at the time. The 1950 census found 14.1% of the District’s 224,142 occupied housing units to be overcrowded (with >1 person per room). By 2011, that figure had fallen two-thirds, to 4.7% (an increase from 3.3% in 2008) — a figure lower than the 5.3% of homes that were extremely overcrowded (>1.5 occupants per room) in 1950.

On average, every apartment and house in DC had one more person living inside — households were 50.2% larger! In 1950, 3.2 people occupied each dwelling unit (for non-whites, it was 4.0). In 2007-2011, the number of persons per household had fallen to 2.13, while the number of housing units had grown to 298,902.

As the city gets reacquainted with the notion of population growth, and begins to plan for a much larger population within the same boundaries, we’ll have to have a realistic conversation about household sizes and housing production. A change of just 0.09 persons per household means the difference between planning for 103,860 units or 140,515 units.* In either case, though, that is one heck of a lot of construction for a city of 68 square miles, of which 10.5 are parks and 7 are underwater. It works out to 2,000-3,000 additional units per square mile — as simple as building a platform and plop 5 DUA suburbia across it, or as complicated as infilling a contentious, built-up city. (More the latter than the former, I suspect.)

That problem can’t be solved with just a few new mega-development sites absorbing all of the demand for urban growth. It requires existing neighborhoods to help absorb some of that demand.

At the same time, Chakrabarti is well aware of the regulatory challenges to merely allowing the market to add density to an already-established city:

At Columbia University, my students and I have been working on a concept I call “cap and trade zoning,” which would allow the free flow of air rights within an urban district, with an understanding that the overall amount of developable area would be capped in relation to proximity to mass transit. This would result in hyperdensity, to be sure, but would also create a “high-low” city of diverse heights, uses and ages. This concept would strengthen small businesses by permitting owners to sell their air rights, while allowing development to occur on nearby lots. Critics may argue that this approach would result in unpredictable development with varying building scales, to which I would reply “Hip hip hooray!” Much of what passes as good planning today is known as “contextual zoning,” a mechanism through which new architecture is tamed into mediocrity by mimicking a false understanding of the scale and aesthetics of existing neighborhoods. Too often this process allows a lowest-common-denominator mentality to trump the wonders of the unpredictable city. Half a century ago, in The Death and Life of Great American Cities, Jane Jacobs relentlessly critiqued the planner’s urge for control; her critique is no less pertinent today.

The concept is good, but what remains to be seen is if it could pass the political test – and if it could adjust the regulatory process (not just the regulatory content) that governs urban development decision-making. Perhaps the first test of the political viability of ‘hyperdensity’ will be if the name helps advance the needed regulatory reforms.

What do we mean by ‘density’?

Greenwich Village - CC image from lumierefl

A few more thoughts on recent discussions of density. Better Cities and Towns offers a summary of Richard Florida’s recent speech (video is corrupted, unfortunately – it gets very choppy 1/3 the way through) at CNU. The twitter summary: quality of place trumps density.

Like previous discussions on the topic, I can’t help but argue semantics. Quality of place is no doubt extremely important – but I would argue it doesn’t trump density at all. Rather, density is a somewhat independent variable. Density is an abstraction, it is merely the concept of how much stuff is in a given space. For many discussions, whether on innovation or affordability or vitality, I would present density as the necessary-but-not-sufficient condition that makes it all work. With that in mind, framing some other factor as one that ‘trumps’ (which I read as if I were playing cards: outranks, surpasses) density seems wrong.

Don’t conflate density and design: From the Better Cities and Towns summary:

One of the false statements is that density and skyscrapers are the key ingredients to urban vitality and innovation. “This rush to density, this idea that density creates economic growth,” is wrong, he said. “It’s the creation of real, walkable urban environments that stir the human spirit. Skyscraper communities are vertical suburbs, where it is lonely at the top. The kind of density we want is a ‘Jane Jacobs density.’”

What is the ‘Jane Jacobs density’? Is it that of her home in Death and Life, the West Village? If so, it’s worth remembering that the West Village is very dense. The 2010 Census (easily accessed with the New York Times’ handy mapping tool) shows the West Village census tracts with population densities in the range of 80,000-100,000 people per sq. mile.

My good friend Mike Lydon linked to a review of sorts of Miami’s Brickell neighborhood, noting many of the urban design deficiencies of the place. Craig Chester writes:

Now, I enjoy Brickell primarily because I can walk for nearly all of my basic human needs – groceries, a barber, a slice of pizza etc. It’s also well-served by MetroRail and Metro Mover, both accessible from my doorstep. It’s a rare Miami neighborhood in that regard. But increasingly, I find myself questioning if Brickell is a “walkable environment that stirs the human spirit” or merely just a semi-walkable streetscape in the shadows of impersonal towers functioning as suburbs in the sky.

First, some context. Brickell’s density from the 2010 Census tops out at 77,000 people per sq. mile in one census tract – surrounded by tracts with much lower population densities. The max there, in other words, is lower than that of the West Village – and the West Village is bordered by residential areas with even greater population densities.

Chester continues with a number of critiques on the urban design of the area – how the buildings interact with the streets, how the retail spaces are arranged, how the neighborhood makes use of the transportation systems, and so on. The descriptions are all fascinating, but I don’t see density as the primary (or even secondary) culprit in any of Chester’s critiques.

I increasingly find myself leaving Brickell on my bicycle in search of more authentic urban experiences found elsewhere in the city. Actually, I need to leave Brickell just to go to a bookstore or bicycle shop….

….usually found in “Jane Jacobs” density.

I’ve not visited the area so I can’t speak to the accuracy of Chester’s critique in person, but I have no reason to doubt the descriptions of the place. However, I think the conclusion is all wrong (echoed by the language Florida uses), and sets up a false dichotomy (and therefore a false tradeoff) between density and place. Searching for a place with ‘Jane Jacobs’ qualities is one thing, but extrapolating that to some magic ‘Jane Jacobs density’ isn’t well supported.

Don’t conflate density and the ‘human scale.’ Another tidbit from the Better Cities and Towns summary of Florida’s speech:

The urban/suburban debate is likewise false, he said. “Great communities and great neighborhoods pretty much look the same,” he said. They are human-scale, include a mix of uses, and are close to transit. “These are the kind of things that people desire, and it is not just in the urban core that you find them,” he said.

I fully agree that the urban/suburban distinction is mostly useless, but the relentless focus on the human scale is another one of those turns of phrase that can be easily misconstrued. While there’s some relation to the absolute scale (building heights, etc), the tradeoffs between human scaled look and feel of a place (e.g. design) and the absolute mass of stuff (e.g. density) are not absolute – as sometimes implied. There’s plenty of room to go up, to be more dense, without sacrificing the human scale – the key is in how you do it.

Density (eventually) requires height, but height does not prevent place. Alon Levy has made the point about the need for height to achieve density at some point. While there’s a tremendous opportunity for the ‘missing middle‘ in most places, many others have market conditions that already demand more space. It’s also useful to remember that density is just an abstraction of stuff/area – the kinds of stuff you’re measuring can vary. Tall Manhattan and short Paris are both very dense, but that’s because the tall stuff isn’t captured in the metric of population density:

Unfortunately, this point is easy to miss, since the headline figure of density is residents per unit of area, and residential skyscrapers are rare. Skyscraper-ridden Manhattan and height-limited Paris have about the same residential density, but Manhattan’s skyscrapers are predominantly commercial. Aside from project towers, Manhattan’s residential urban form is mid-rise, with most buildings not exceeding 6-12 floors; this is similar to Paris.

So, yes, we must build up at some point:

To get higher density, one must build higher. Some parts of Manhattan do: the Upper East Side and Upper West Side have a fair number of buildings in the 20-30 story range, and although as Charlie computes only 1% of New York City’s residents live above the 19th floor, the proportion is much higher on the Upper East Side and Upper West Side, and becomes even higher if one relaxes the limit from 20 floors to 12, already well beyond the limit traditional urbanists and high-rise opponents accept (Christopher Alexander proposes 5 as the limit).

Height does not prevent place – human scaled urban design can work in incredibly dense places with tall buildings, because the key elements to the human experience is what goes on at street level. New Yorkers don’t look up at their skyscrapers because it’s not a natural position for a human. Our HDTV screens mimic our own physiology – wide, peripheral vision with limited vertical views. Develop the first 5 or so stories well, provide some setbacks for the taller portions above that, and you’ll do just fine for creating a sense of place at a human scale. Adherence to this scale need not be absolute.

Beware statements of universality. It’s interesting to see one kind of density (even if people are really arguing for place, not density) pushed out as the ‘right’ level of density. There’s a big difference between observing various geometric rules of an environment and pushing one’s taste, via observation, as if it were the rule.

The argument about the “Jane Jacobs density” is a great example. West Village densities would represent a tremendous increase in most places around the US – just not in New York. New York is the exceptional case. Achieving Greenwich Village densities in other cities might be a tremendous increase – likewise, maintaining Greenwich Village densities in New York’s context (given the market conditions, etc) is likely a severe constraint on supply (see Ed Glaeser).

So, what makes the ‘Jane Jacobs density’ the right density? How can anyone even pretend to know what that would be, without considering the context, the market conditions, the baseline of development, etc? One element of Ryan Avent’s The Gated City that I admire was his steadfast refusal to state which level of density is ‘correct’ or ‘right’ or ‘good,’ but rather to focus on the process that cities go about changing their densities (and how that process is currently constrained by things like zoning codes).

Likewise, Ed Glaeser’s Triumph of the City focused on the market aspects of density, as far as density and overall supply are related. So long as the cost of new stuff (housing, offices, etc) is fairly even with the cost of construction, then you’ve got a fairly efficient market. This could be a step towards defining what the ‘right’ density is, but of course that answer is going to provide a different number in every situation.

On density and design tradeoffs

Bethesda Row - note that you don't even see how tall the buildings are - CC image from faceless b

Kaid Benfield’s excellent blog had a post last week on the need for better urban design and management of the public realm in our new, dense infill development. And while I certainly agree with the need for better urban design, I take issue with Kaid’s implication of an explicit trade-off between density and design – that is, the more density you get, the less human-scaled the street will feel as if this were some correlation of a natural law.

Kaid’s post shows several comparison photographs taken from Google streetview, many from the DC area. What’s missing is an actual accounting for the density embodied in those pictures (such as the visual survey posted here). Additionally, some of the photos Kaid compares are not similar photos – one example involves a view down the axis of a street, while the other is a view of a building’s first floor and the accompanying sidewalk.

For me, it’s a completely different feel. The second development, part of Bethesda, Maryland’s terrific Bethesda Row area, is not just more inviting but also a bit smaller in scale, at five or six stories tops. But that’s part of it, in my opinion. To increase density enough to make a difference, we don’t always need to maximize it. Much of the time a moderate amount of human-scaled urbanism will be far more appropriate than a high-rise. This isn’t, or shouldn’t be, just about calculations of units per acre or square footage. It’s also about what feels right to people.

The sentiment that “we don’t always need to maximize” density implies a tradeoff between human-scaled design and density that I don’t think is absolute. To a great degree, the influence of design – at the street level in particular – is the key element of a human scale. In the comments, Payton (assuming this is from Payton Chung) adds this:

I’d agree that it’s almost all about design. The low- and mid-rise floors are most important, to be sure, since humans’ peripheral vision is weakest when looking up. However, there are plenty of historic skyscraper districts that maintain a great sense of place and small scale at the street level (Broadway in Los Angeles is a thrill to walk down), and even some which maintain good sunlight at street level (just was at Rockefeller Center for the first time in a while and reminded of that crucial detail).

Encouraging both smaller parcel sizes — for exactly that granularity, and to ensure greater diversity — and mid-rise heights both ask huge concessions from our current bigger-is-better development paradigm. Of course a developer will build out to whatever envelope the regulations will allow to recoup their costs, will charge high initial rents that only the most reliably profitable (i.e., bland) retailers can afford, and often won’t spend a premium on the sort of pedestrian-scale details that really create a great sidewalk environment. Yet other factors also result in these squat, boring buildings. Occupants will pay a premium for “ground-related” space or for high-rise space with a view, but not for the mid-rise floors. (Compare that to the 18th and 19th centuries, when the 2nd floor commanded the highest rent as it were above street dust but not a long walk up.) High-rise life safety and structural requirements make a 6-story building almost as expensive as a 12-story building. Requirements for exit stairs (like restricting scissor stairs), and tenants’ desire for reconfigurable spaces, both fatten floorplates. Municipalities set build-to lines for bases (correct) and, fearful of oddly height-obsessed NIMBYs, set unrealistically low height limits.

For things like sunlight at street level, the more important considerations would be the orientation of buildings on the site and the setbacks rather than absolute height – issues of design of a different sort than the street level scale.

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.

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).

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.

Defining 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.

Perceptions of density often miss the mark

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

City Block

a work in progress…