Slums, Titles and the World's Simplest Zoning Code

Although from the perspective of a resident of the United States, Canada, Western Europe or a handful of other countries, the organic pattern of city growth might seem to be a historical bygone, visible only in those portions of cities developed before the late 17th century, the last 50 years have in fact produced the greatest wave of emergent urbanism in human history.  This growth, reflected in the so-called slums of South and Central America, Africa and Asia, utterly dwarfs in scale any formally-planned public housing built during that time, and currently houses between 1 and 1.4 billion people worldwide.

"Slum" (Rio De Janeiro) and below ...

These settlements, built with virtually no guidance or oversight, produce urban environments of extraordinary complexity, beside which even the most carefully designed project can seem simplistic by comparison.  Although they are not always beautiful in a conventional sense, their astonishing variety makes them a favorite of photographers with an artist's eye and appreciation for the visual interest of a basic built form repeated in endless irregular variations across a dramatic landscape, much like the Italian Cinqueterre or the towns of the Aegean islands. 

... international tourist destination (Riomaggiore).

A New York times article, writing about the Mumbai slum that was the setting for the film "Slumdog Millionaire," describes how the visual complexity of these places is matched by their economic complexity and the resourcefulness of their inhabitants -- an inventiveness that recalls Jane Jacobs' observations in The Economy of Cities:

"Understanding such a place solely by the generic term “slum” ignores its complexity and dynamism. Dharavi’s messy appearance is nothing but an expression of intense social and economic processes at work. Most homes double as work spaces: when morning comes, mattresses are folded, and tens of thousands of units form a decentralized production network rivaling the most ruthless of Chinese sweatshops in efficiency. Mixed-use habitats have often shaped urban histories. Look at large parts of Tokyo. Its low-rise, high-density mixed-use cityscape and intricate street network have emerged through a similar Dharaviesque logic. The only difference is that people’s involvement in local development in Tokyo was seen as legitimate."

The traditional response to such settlements by city and national governments, still common today, is to evict the inhabitants and demolish the structures. Uprooting the community in this fashion destroyed the energy and scarce resources that the residents had put into their dwellings, disrupted social and economic networks, while the construction of new public housing, intended to host at least some of the displaced residents, redirected government revenue that might have been used to improve the existing settlement to building an inadequate number of units which were poorly suited for people's social and economic needs. 

More recently, in acknowledgment of the counterproductiveness of demolition, various South American governments, notably Mexico and Peru, have begun issuing formal titles to the possessors of slum properties.  The stated purpose of this approach, advocated by economist Hernando de Soto and endorsed by none other than Milton Friedman, is to increase tenure security and to permit the land to be used as security for business loans. 

So far, although titling of properties has led to an average 25 percent increase in land values, the promised access to capital has largely failed to materialize.  Further, the awarding of formal titles has often served as an invitation to outside real estate interests to enter the market, futher inflating prices and potentially driving out the very people whose tenure the titling program was purportedly designed to protect.  In Mumbai, this process took the form of large apartment towers sprouting in the low-rise Dharavi slum, adding height without necessarily increasing density (in any event population density in these areas appears to be exceptionally high even in the absence of buildings over three stories).

An alternative approach, adopted mainly in the Brazilian city of Recife, has been to provide tenure security not with titles, but by recognition of the community's claim to the land, combined with the implementation of what is perhaps the simplest zoning code to be found anywhere in the world: 1) a two-story height limit; and 2) a maximum lot size of 150 square meters (1,615 square feet).  Informal exchanges of property, without deed recording or title transfer, continue unhindered, reducing transaction costs and encouraging an extremely flexible urbanism where boundaries and structures rapidly adapt to changing needs. 

Mathieu Helie argues that the remarkable organic form of these slums is dependent on this openness -- an attempt to make them conform to a particular notion of property rights (that of individual freehold ownership by way of titles, deed recording and plat maps) is to deprive it of the flexibility that allowed it to take shape in the first place:

"After praising slums for their ability to generate economic opportunities, they are denounced [by a City Journal article] for not fitting into the conventional model of property rights. Yet it is precisely the use of more natural methods of property allocation that gives slums their organic morphology. ...

"Just like we can’t make the organic morphology of slums fit into the modern rules of property ownership, we can’t make traditionally emergent cities through the current planning system. (All efforts to produce traditional neighborhoods have so far produced only imitations of them.) ..."

The question of how to produce such traditional or emergent environments in a developed country in the present day is one which people such as Christopher Alexander have devoted their careers to, but answers, in practice, remain elusive.  The example of places like Recife does suggest the answer could be simpler than ever imagined.

Sources and Additional Reading:
Urban Land Tenure Options: Titles or Rights?
Regularization of Informal Settlements in Latin America
Secure Tenure in Latin America and the Caribbean
The Role of Urban Slum Titling in Slum Improvement

Density on the Ground: Cities and Building Coverage

Buenos Aires

Alon Levy has a new post up about height and density where he argues that to move beyond a certain density, a city will ultimately have no choice but to build upwards.  Density is not simply a function of the height of buildings, however, but also depends upon the area that they occupy.  A city in which buildings occupy a relatively small proportion of the total city area will have room to grow either vertically or horizontally (the latter of these represented by the process of street narrowing, or other forms of infill).  

Allan Jacobs in his book Great Streets features a section in which he presents painstakingly drawn figure-ground maps of several dozen of the world's best-known cities.  Although he calculates the intersections and number of blocks per square mile, both indicators of connectivity and pedestrian accessibility (see Laurence Aurbach's site for more on this topic), no figures are given for the proportion of city land occupied by buildings and rights-of-way (and other public spaces) for each city. 

Portland

Although performing these calculations for all of his chosen cities would be a major undertaking, I've put together some approximate figures, with abundant help from Google maps, for a selected range of cities, both American and not.  Shown are the proportions of each city occupied by 1) buildings or buildable land; 2) rights-of-way, including streets and sidewalks, and 3) other public spaces, including parks and plazas.  Unless otherwise stated, these figures refer to the general downtown areas of each city:

A few quick notes: St. Nicholas Houses is a public housing project in central Harlem composed of cruciform towers on a superblock.  New York's figures include Central Park.  Measuring park and plaza spaces in organic cities like Paris or Vienna is a bit of a challenge: depending on the area examined, for instance, Paris' figure for parks might be somewhat higher.  Fes is just an estimate, as the narrow footpaths of the city's old town are barely visible from above, but in any event it appears to be about the maximum possible built coverage possible without moving to an entirely streetless city.

Hopefully these numbers can provide one additional angle on the density question.  I have some ideas how they might be paired with Jacobs' figures and some other measures to provide an even fuller picture of both density and connectivity, but I'll save that for another post.

Related posts: Charting the Grid

Glazer v. Glaeser on Density

I've been reading through Nathan Glazer's essay compilation "From a Cause to a Style: Modernist Architecture's Encounter with the American City," and want to excerpt the following couple paragraphs in light of Ed Glaeser's recent book, Triumph of the City:

"Most significant, designers failed to explore just what it is people find attractive in areas and buildings for whose design characteristics not much, if anything, can be said.  How often have we seen those pictures of endless Levittowns, little houses with scarcely grown trees spread out over the landscape, as horrible lessons to avoid?  And how often have we contrasted them – to their disadvantage – with gleaming visions of great towers?  Let us put aside for a moment the detailed economic arguments that justify density, and let us recognize that very often the overall cost of single-family homes packed closely, or apartments in low-rise buildings, would compare favorably with twenty-story apartment towers. ...

"Wherever social scientists examine these issues, they find a taste that architects on the whole do not find it interesting to satisfy, a taste for the low-rise, the small scale, the unit that gives some privacy, some access to the ground, a small piece of land wholly under one's control.  I am not, of course, describing a universal taste,  But for people raising children – and indeed many others – it is a near universal taste, if people have a choice.  Nor is there any reason to think that is is necessary or desirable that people be educated against that taste and develop a taste for a larger or gargantuan scale…"

This particular perspective represents, I think, one side of an ongoing split of opinion among "pro-urbanist" writers and thinkers.  On the one hand (at the risk of oversimplification, apologies if I have misrepresented), there is Ed Glaeser and others such as Matt Yglesias, Ryan Avent and Stephen Smith, who overall take an economically libertarian approach to urban density, opposing height limits and touting the benefits of increasing concentrations of jobs and residences in urban areas.  The advantages of an increase in density are always, or nearly always, understood to exceed those of restricting that density by regulation; or, put another way, that any artificial distortion in the market for the ownership and free development of land, however well intended, is likely to lead to economically inefficient outcomes.

On the other side are what I might call the "quality-of-life" urbanists, such as Christopher Alexander, who advocated a four-story height limit, and others including Glazer, Michael Mehaffy, Nikos Salingaros, Leon Krier and evidently David Sucher, who promote a view which, while considering economic arguments, gives equal attention to those which cannot be easily quantified.  The desire of families to live in single family or low-rise homes is accepted, the general dislike of living in tall apartments, where another choice is available, is acknowledged, and the task instead becomes one of finding the urban form which maximizes density while producing an environment pleasant enough that it does not send families fleeing for "Levittown" when the first child arrives.  If this task requires establishing height limits, then these limits will be considered, as will certain other forms of regulation.  

This of course an oversimplification of these two perspectives, but they have been contrasted recently (some of the finer distinctions are brought out in this article by Kaid Benfield, for example, and the recurring debates over the DC Height Act).  At the same time, both positions share a common dislike of other forms of regulation: excessively segregated zoning, mandatory low density development and so forth.  There may actually be more in common than not, with quibbles over certain issues interfering with agreement on other certain fundamental concerns. 

Related posts:  

Mehaffy on Skyscrapers

Can New York Build Its Way Up To Affordability?

More On Density

The New York That Wasn't (But Might Have Been), part II

Before showing an illustration of a Manhattan as it might have grown in the absence of a single central plan, it's worth considering for a moment how it was that the plan that the Commissioners drew up actually came to be, in spite of the extensive network of roads that already covered Manhattan in 1807.  Answers are difficult to come by, as the Commissioners' very brief account of their decision-making process raises nearly as many questions as it answers.

The Commissioners did, however, claim that they had attempted to follow existing streets and property lines:

"Having determined, therefore, that the work in general should be rectangular, a second, and, in their opinion, an important consideration was so to amalgamate it with the plans already adopted by individuals as not to make any important changes in their dispositions.  ... This, if it could have been effected consistently with the public interest, was desirable, not only as it might render the work more generally acceptable, but also as it might be the means of avoiding expense. It was therefore a favorite object with the Commissioners, and pursued until after various unsuccessful attempts had proved the extreme difficulty, nor was it abandoned at last but from necessity. To show the obstacles which frustrated every effort can be of no use. It will perhaps be more satisfactory to each person who may feel aggrieved to ask himself whether his sensations would not have been still more unpleasant had his favorite plans been sacrificed to preserve those of a more fortunate neighbor."

1782 British Headquarters map with existing streets
and roads highlighted

Leaving aside the absence of any explanation on this fundamental point, and the debatable conclusion that it is preferable to frustrate everyone's interests than to frustrate only some, another point worth noting is that the Commissioners attempted to accommodate existing interests to the plan only after "having determined ... that the work ... should be rectangular."  Since the existing roads of Manhattan largely followed an organic pattern, as can be seen at right, any attempt to conform them to an inflexible rectilinear grid was doomed to failure from the start – a fact which would have been immediately obvious to an experienced surveyor such as Commissioner Simeon De Witt.

This order of consideration could only be justified if the Commissioners believed that the public advantages of the grid plan outweighed any public benefits to be gained from following existing streets and property lines.  Such a comparison of costs and benefits is not made in the Commissioners' report, however.  Instead, the Commissioners compare the unadorned grid to a caricature of Baroque city planning ("those supposed improvements by circles, ovals, and stars which certainly embellish a plan") an oversimplistic and unserious exercise which seems designed to set up the choice of the grid without having to explain its supposed benefits. 

The same map with farmland boundaries
drawn in as new streets and roads

In fact, only one benefit of the grid is ever stated in the report: that "a city is to be composed principally of the habitations of men, and that straight-sided and right-angled houses are the most cheap to build and the most convenient to live in."  Even assuming for the moment that this statement is true, it is irrelevant, since virtually all cities, from L'Enfant's Washington D.C. to the medieval city centers of Europe are composed overwhelmingly of straight-sided and right-angled houses -- including 17th century New York itself, where every house appears to be straight-sided and right-angled, just as most of the houses of old Amsterdam were. 

By contrast there are two clear advantages of following the existing roads within the Commissioners' own report: 1) it had more public support and 2) it was less expensive -- not surprising, since the roads were already present, and did not need to be surveyed, marked or excavated.  Had the existing farmland boundaries formed new streets and lanes leading from the existing roads, in a typical pattern of incremental organic growth, the pattern would have grown still more complete, as shown at left.

So what was actually underlying the Commissioners' decisionmaking?  Peter Marcuse in his 1987 essay concludes that "the grid in 1811 in New York signalled the triumph of the interests of larger landowners and speculators over all competing concerns," indirectly suggesting that the Commissioners' stated concern for the public good was an empty gesture.  In this view, the "convenience" of the plan mentioned in the report reflected only that the grid was easy to survey and created lots that were easy to track and sell.  Perhaps the Commissioners, having been entrusted to "plan" the city, also could not imagine a form of "planning" that did not involve drawing straight lines and right angles.  Whatever the reason (and ease of surveying can't be ruled out), this planning idea caught on, and as Marcuse observes the remainder of the century saw thousands of American towns and cities laid on on regular grids.  

Still, with use of the 1782 map shown here, it is possible to consider what might have happened if the Commission's task had been limited by the New York legislature to only surveying the roads in existence, and marking out new lanes along existing paths and boundaries -- or if no Commission had come into existence at all (while further taking the license of omitting some of the speculative grids which were laid out between 1782 and 1811).  With many additional streets filled in according to topography and property lines, I'll leave you with one version of how that lower Manhattan might have eventually looked:

The New York That Wasn't (But Might Have Been), part I

The Commissioners' plan.

An attempt at a more reflective piece today as a short break from garages and alleys. (Updated 6.18.11 with Urbanphoto link).

March 2011 marked the bicentennial of the Commissioners' Plan of New York, the document which laid out Manhattan's familiar street grid from the vicinity of Houston Street north to Harlem.  In recognition of this milestone, there's been a modest amount of reflection on the plan both in the press and in the blogosphere, with some praising the plan, and others thoughtfully ambivalent.

In the past, however, the critical voices have generally been the loudest. Peter Marcuse in a 1987 essay referred to it as "one of the worst city plans of any major city of the developed world;" Frederick Law Olmsted criticized it for its "rigid uniformity;" John Reps noted its scarcity of sites for public buildings, lack of enough north-south streets, and frequent intersections creating traffic congestion; others have faulted it for obliterating Manhattan's natural landscape, while Recivilization has perhaps the most memorable turn of phrase, calling the Commissioners' plan "breathtaking in its monotony."

In spite of all these critiques, there's been relatively little thought devoted to what an alternative to the grid might have looked like.  To the extent that they are discussed at all, alternatives generally take the shape of the Baroque plans of the late 18th century in the manner of L'Enfant's plan for Washington D.C., with diagonal boulevards and grand circles, as one Columbia design class recently imagined.*  More realistically, Urbanphoto has an outstanding post on an earlier plan drawn up by city surveyors John Mangin and Casimir Goerck which was somewhat more more accommodating of the street networks already emerging north of the city.

*(The Commissioners had, in fact, considered such features and rejected them for ostensibly utilitarian reasons, although little more than a century later the planning departments of checkerboard cities such as Portland would note a lack of diagonal routes as a major utilitarian shortcoming of the grid).

There is another possibility, however, one that requires acknowledgment that the Commissioners' plan did not cover virgin ground, but rather overlaid and blotted out a complex network of roads, streets and paths that already covered Manhattan as early as the 1770s.  In the British Headquarters map of 1782, featured prominently in Eric Sanderson's recent book Mannahatta, not only is the former Indian trail of Broadway clearly discernible running the length of the island, but dozens or hundreds of other roads also, large and small, serving the many farmhouses and budding villages north of the city limits.  These roads were not planned by a single mind, but worn into the terrain by countless feet following a subtler intelligence: the intuitive search for the smoothest, most level and most direct paths to the most important destinations, perfected by repetition over years, decades and centuries. 

Oddly, it is this process of road and street formation -- which Spiro Kostof refers to as the organic typology -- which earns the least respect from writers on urbanism.  On New York's organic street network in lower Manhattan, dating to the days of the Dutch settlers, it's easy to find statements like these:

"Until the grid most New Yorkers were clustered below Houston Street in a confused maze of streets and lanes."

"Prior to the Commissioner’s grid plan, the city’s streets had been laid out rather willy-nilly, as befitting a city that was founded in essentially late mediaeval times..."

There seems to be an assumption that if a street network does not have obvious regularity or other indisputable evidence of direct human design, then it must be simply random and therefore, impliedly, inefficient or unsuited to the needs of the people living along it.  But was this street network really "confused" or "willy-nilly"?  Here is an adaptation of the Castello Map of New York, dating from 1660 and showing the streets and homes of the city at that time:

The Dutch origins of the city, with its canals, are obvious, but the functional logic of the streets, though evidently not formally planned, are anything but confused or irrational.  Broad streets carry commerce to and from the waterfront and gently angle northwards, reflecting the natural course of trade unencumbered by sharp right-angled turns.  Single-family homes are being built along the quieter narrow lanes running perpendicular to the thoroughfares, with the process of block subdivision reflecting the higher value of land close to the docks. 

There is an elegant mathematical order to the street network as well: each curve of the broad streets defines a shape which mimics the shape of the island itself.  This is a typically fractal pattern, defined as "a rough or fragmented geometric shape that can be split into parts, each of which is (at least approximately) a reduced-size copy of the whole."  (See Mathieu Helie's extensive writings about this idea in the context of architecture and urbanism.)  This particular pattern is presumably the result of accommodating a grid-like network of streets, with blocks of roughly equal size, to the constrained geography of Manhattan. 

In the following century, this initial plan was organically extended north of the wall, guided by pre-existing paths and roads.  In the following post I'll show a rendering of what might have resulted had the city of the 1790s simply decided to let this process, ongoing at that point for almost 175 years, continue to follow its natural course.

New World Economics on SFDR in the Traditional Style

Nathan Lewis's latest urbanism post is up at his website, this time dealing with the topic of whether it is possible to create a neighborhood of single-family detached residential (SFDR) with room for cars which nonetheless is dense, walkable and pedestrian-centered on narrow streets:


Seijo neighborhood, Tokyo



"I am rather hesitant to take up this topic, because it is not my goal at all to build some sort of slightly improved auto-dependent suburb in Suburban Hell, but to create Traditional Cities instead where a car is not at all necessary. However, there is a place for this I think. First, the SFDR pattern is also a valid one for the pedestrian Traditional City. European examples of Traditional Cities tend to have a lot of apartments, but Tokyo in fact had very few apartments until the 20th century. The normal pattern was for very small SFD houses on very small plots. In fact, the first Western-style apartment building in Tokyo wasn't built until the 1920s. It was a Western idea they borrowed. ...

Second, although I promote a Traditional City in which cars are entirely unnecessary, and that you can walk everywhere or take a train to another place where you can walk everywhere, nevertheless there is perhaps a need for a kind of transition format in the U.S. For example, let's say you lived in the Washington DC area within walking distance of a train station, that you can take to work in downtown DC. So, you don't need a car for commuting, but still you need a car to interact with the rest of the U.S., which is still car dependent."

Thus, can we think of a pattern which is compatible with BOTH today's need for two to three cars per household, the desire for the SFDR format, and ALSO compatible with the Traditional City pedestrian-centric design including of course Really Narrow Streets? This is a rather touchy design goal, as you can see, since we want to have one foot in two worlds which have a fundamental incompatibility.

Let's formulate some ideas along these lines..."

Read the whole thing, with tons of illustrative maps and photos, here, and feel free to leave any feedback below as Nathan's website doesn't allow comments.

Garages and Alleys 3: Reworking the Block

In response to the previous post, commenter Cambias perceptively noted that the example I'd posted of Washington D.C.'s Capitol Hill neighborhood has considerably larger individual lots than those on the new blocks being built up in Capitol Quarter.  This of course makes it easier for the Capitol Hill lots to accommodate both private backyards and detached garages. 

To show that this is an issue of design, not simply acreage, I've taken the same block from the previous post (below, at left) and proposed an alternative configuration with the goal of providing 1) some backyard space for each house with 2) at least one parking space per unit.

By eliminating front setbacks and narrowing the streets by about five feet on the east and west sides -- still enough to allow for parking on both sides of the street -- this goal can be achieved.  On street parking has increased to 65 from 52, thanks to the new center street, serving a total of 64 rowhouses, compared to 54 previously.  Additionally, each house now has a small, courtyard-like outdoor space.  It's just one possible layout of many, and I'm sure people can suggest changes and improvements, but my intent is only to show that this very same area can actually be redesigned to accommodate those features I'd criticized other plans for lacking.

The only complication here is the 1950s era DC Zoning Code, which appears to still require 1 off-street space per every 2 units in this particular residential zone (R-5-B).  This can result in the absurd scenario of interior garages and curb cuts which take away as many on-street spaces as they add, although it appears off-site requirements may now have been waived for houses without alley access.

Update: In response to Alex's comments, here's another arrangement that allows 1/3 of the townhomes space on which to construct garages fronting on the center street.  As to how many people would purchase a garage if offered one as an optional feature, or what the price differential is between homes with the potential of a garage and without, I have no idea (although it's worth mentioning that DC does have the second lowest proportion of car commuters of any major US city).