Emergent Urbanism

Modeling the processes of urban emergence

June 30, 2009 · 3 Comments

Placelife

The growth process of an emergent city actually consists of five growth processes. These processes are hierarchically related, that is to say the morphology decided by processes at higher levels of complexity depends on decisions taken at lower levels of complexity. They are not constrained by one another, as modern planners claim when they clear slums in order to build their architectural vision, but expand upon one another, creating a landscape that is tied to a history of adaptation and transformation in order to meet the needs of the present at every point in time.

Each transformation is the decision of an individual, acting within the context he perceives and the ends that are identified. These ends may be within his own sphere of life, by expanding his home, or subdividing his property to build a home for his grown children, but more likely they are the consequences of identifying a potential created by the individual actions of others. For example, if a sufficient number of neighbors have settled, opening a bakery. In this way networks are built upon the potentials created by the last network extension, (in one such instance by capturing residual movement in the grid as Bill Hillier describes) and the city increases in complexity.

The foundation process of a city, before anyone can even imagine a city being there, I call the place. A place is nothing more than a free surface available to be settled. Newcomers build their home wherever they want in the place, and that implies that they will locate their homes to take maximum advantage of natural features, and space themselves away from their neighbors in order to avoid conflicts over the use of common lands. A place settlement process is how shantytowns are created, except that because there does not exist any functional land ownership in a shantytown there is no limit to how many buildings can be created. Thus the shantytown never reaches the second process of urban emergence, creating a crisis. A place may be created deliberately, by transforming a farm or other types of land use to that purpose, by building fortifications within which land is protected from harm, or a place may be given by nature simply by being available and strategically located.

Place

A place is an open space where people may settle and build randomly

As places become increasingly dense, the use of space by neighbors will create conflicts of proximity. Land will no longer be superabundant. In order to resolve these conflicts a process of land enclosure delimits the boundaries between neighbors’ households by negotiating the boundaries of land that is in private and common use. Streets and blocks thus appear, and those spaces where common use is particularly intensive, because of highly valuable natural features or central locations, become recognized as public squares and greens.

Enclosure

Enclosures delimit private and public spaces, and the pattern of streets, blocks and squares emerges.

With available land to settle either enclosed or occupied by public activities, it becomes more difficult for new growth to take place. New buildings built on remaining place must be justified before a community increasingly protective of the remaining open space. In most cases it is much simpler to ask one of the members of the community to give up a part of his property in order to grow the new part of the town, introducing the process of subdivision. These subdivisions are negotiated case-by-case and thus adopt random sizes and shapes, creating a fractal distribution of lot sizes over a long timeline. Some subdivisions split the land into shared courtyards and cul-de-sacs that are administered under a co-property agreement (they never need to involve the community as a whole).

Subdivision

Properties are subdivided to make room for new growth and new network relationships now that open land is in short supply.

Eventually crowding becomes problematic at the same time as the scale of network growth is increasing due to higher population densities. This creates the opportunity not only to open new places to settlement, but also to connect the central city to these new places by a place functioning at a greater scale, near a road or highway, and that provides an encircling bypass around smaller-scale neighborhoods. This is the grid process. This new construction opens up land to construct large market and industrial businesses that are simultaneously a buffer between smaller-scale places and roads but also an integrator of these places into larger-scale networks.

Grid

The grid integrates mature places into a larger network of places, and creates new spontaneous development opportunities.

The last process takes place when a large city with many places integrated by many scales of grids develops a mass transit system that becomes more reliable than private transportation systems. When that occurs the need for private transportation falls radically and it becomes possible to live at the centers of this mass transit system without any private transportation, thus radically reducing demand for space. Parking lots can be built over and turned into undifferentiated buildings providing standardized living spaces that can find their match in the very large population. This radically higher population in turn creates a very wide potential for new differentiated networks, and the construction of large buildings is accompanied by many new, differentiated small buildings. This is what enables a place to achieve high density complexity, and we can call it the metropolitan process.

Metropolitan

A small number of larger new buildings accompanies a large number of small new buildings resulting from the reduction in space needed for transportation.

A model such as this one is not meant to be a design to be implemented in reality. It serves only as an illustration of the processes, the means through which decisions are achieved, that generate the structure of cities. If we want to do the morphology of an existing city, it is these processes that will help us explain what decisions led to the city’s present form. These processes also help us predict the future of the model of urban development we choose to adopt. As an example I have become highly critical of measures that seek to increase the density of subdivision developments by smart growth zoning regulations. They tend to leave the structure of neighborhoods in such a state that further subdivision processes within its tissue are impossible, and the neighborhood becomes unable to adapt itself as its population changes. Instead we should be building low density subdivision developments that can grow naturally into metropolitan neighborhoods, and this growth will be controlled by its community as its members make the decision to give up a part of their property to accomodate the changes the community is undergoing.

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The genesis of complex geometry

June 21, 2009 · Leave a Comment

I don’t believe that there is a dichotomy between a supposedly modern and traditional architecture. Instead there exist different geometric processes, and while traditionally builders have employed nesting processes in their work, for perhaps no other reason than it came naturally to them, modern builders have restricted themselves to linear geometric processes due to drawing their inspiration from cartesian science and engineering.

In attempting to transform architecture into a vessel for artistic expression, modern architects have been trapped by their limited tool set, and the product of their work has often been confusing, silly, or utterly corrupt. There are only so many tricks that one can perform with linear geometry, although computers have extended the reach of those tricks. But the confusion of modern architects becomes even more obvious when they ascribe artistic merits to traditional builders who never aspired to be artists at all. One such instance is the introdution of a recent biography of the 18th century french military engineer Vauban by official starchitect Jean Nouvel, who described Vauban’s fortresses as an early form of land-art and morphing. Jean Nouvel asks, could a man be an artist without being aware of it? Vauban was not an artist at all. Military necessity led him to employ geometric processes that significantly increased the complexity of fortifications, and it is merely incidental that today we find his projects to have artistic merits.

The process through which Vauban’s work became worthy of architectural praise provides the key to the distinction between linear and nesting geometry. Vauban was not himself the inventor of the star fort. Those had been around for more than a century when he began his career for the army of king Louis XIV. The basic star fort was a simple concept: the old masonry walls of the medieval age had shown themselves to be obsolete with the advent of cannons, and they had been replaced with thick banks of earth dug out of trenches whose major flaw was to provide space out of reach of defensive fire at its angles. The angles were thus extended into diamond-shaped turrets in the first pass at a feedback correction, introducing nesting geometry and initiating the first step of the genesis of a fractal.

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A basic, early star fort

While the star fort was successful at resisting attacks, it was not impregnable. A method was devised to capture them by digging trenches in zig-zagging patterns through which troops could assault the walls without being exposed to cannon fire. In fact this is how Vauban built his career, and some of his “plans” for besieging star forts are significant civil engineering projects of their own.

Siege de Turin 1706

The siege of Toreno. From an encircling trench, Vauban built successively denser trenches to capture the citadel and take the city, a process that was extremely expensive and time-consuming.

While star forts never truly became obsolete (as medieval fortifications had) until well into the 19th century, military engineers did improve on their effectiveness by correcting their vulnerabilities, which happened to be at the angles they were characterized by. And so, by another layer of feedback, the geometric depth of the star fort concept increased.

Citadelle San Martin

San Martin Citadel, a “second generation” star fort.

Vauban’s great invention was nothing much more than repeating this process of increasing depth one more time, creating what many now consider to be his masterpiece, the Citadel of Lille, a showcase of complex geometry made from the refinement produced by centuries of feedback of the star fort concept.

Citadelle de Lille (2)Nouvelle enceinte de Lille

Citadel of Lille and the system of fortification of the City of Lille, as designed by Vauban

If you only understand cartesian processes, then the only idea that may come to you to improve on the basic star fort would be to add dozens of diamond-shaped turrets, a change that would most certainly make the concept worse instead of better. The military engineers of the time however were well aware that the diamond turrets were optimal in their shape. What was needed was a shape that extended the diamond, and this was achieved by increasing the depth of the whole object.

Another aspect of the complexity of a geometric process seen in the Lille example is its configuration adaptiveness. The shape of the city and the surrounding landscape is completely random, and the encircling fortifications bend to match this randomness, leading to Nouvel’s claim that it is an early example of morphing. But once again there is no deliberate attempt at morphing going on. Since each component of a star fort is defined as a recursive relational transformation of the basic wall, Vauban only had to design the wall and the other parts aligned themselves as a result of the wall’s configuration. If the outcome has artistic value, it is once again only incidental.

It is important to note that the Vauban extensions to star fortifications did not mean that the simple 3-part star fort became obsolete. In fact many simple star forts were built in the 18th and 19th century in America as the threat was low and the cities to be defended underdeveloped. The difference between a simple fort and Vauban’s complex fort is one of depth and effectiveness, and there is a real cost-benefit choice to make. The star fort only became obsolete when the bunker replaced it, and the early bunkers reset the process of complex geometry genesis by being simple concrete shells in their early incarnations.

When we undertake to create symmetry in an urban environment, we want buildings to be as alike as possible while allowing for adaptation to context. If we understand geometric depth we can build in such a way that poor and expensive buildings have the same basic design in their first levels of geometry, but expensive buildings have many more scales of geometry nested within that basic design. It is not necessary for an entire city to be made of the same materials as materials are one of the last visible scales of geometry, and so we can have a city of mud bricks and marble buildings that nevertheless share 95% of their geometry and beautifully complement each other, while both poor and rich citizens have a home adapted to their situation.

We can look at these examples from Korean traditional architecture for an illustration.

48799484.CIMG0512Tomb_of_King_Tongmyong,_Pyongyang,_North_Korea-2

On the left is a simple house and on the right is the tomb of a great king. Both buildings have the same design, but the building on the right has much greater depth in this design.

Another interesting comparison is between the Golden Gate bridge in San Francisco and the Verrazano Narrows bridge in New York.800px-Golden_Gate_Bridge_from_underneath800px-VerrazanoFromNCLDawn

The bridges are the same in design, but the Golden Gate bridge has more depth within this design, and is for this reason the more famous of the two bridges. That doesn’t mean the Verrazano Narrows bridge isn’t beautiful on its own.

And to make things as simple as they can get, we can compare a Sierpinski triangle with four levels of iteration with one that has six levels.

Geometric depth

The fractal on the right has all the same elements as the one on the left, but also has more.

A lot of the residential buildings we create today would benefit from being more like the Verrazano Narrows bridge. They try to be more than a simple house for a simple family and end up covered in tacky, useless ornament that have obviously been forced into the design. Simplicity, if it is adapted to context, can create as beautiful a landscape as complexity. Postmodernistic nonsense geometry does not. We would be better served going back to the simplicity of 1950’s international style modernism than what is being built by architects today. The best architects would reinvent it with greater depth.

Previous topics

References

Vauban, l’intelligence du territoire

Hommage a Vauban 1969

A modern artist’s hommage to Vauban. This artist did not understand complex geometry.

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Don’t demolish Detroit

June 16, 2009 · 2 Comments

The following story about a presidential program to demolish whole neighborhoods of inner city fabric in the United States and turn them back into wilderness has been making the rounds around news blogs.

Having outlined his strategy to Barack Obama during the election campaign, Mr Kildee has now been approached by the US government and a group of charities who want him to apply what he has learnt to the rest of the country.

Mr Kildee said he will concentrate on 50 cities, identified in a recent study by the Brookings Institution, an influential Washington think-tank, as potentially needing to shrink substantially to cope with their declining fortunes.

Most are former industrial cities in the “rust belt” of America’s Mid-West and North East. They include Detroit, Philadelphia, Pittsburgh, Baltimore and Memphis.

In Detroit, shattered by the woes of the US car industry, there are already plans to split it into a collection of small urban centres separated from each other by countryside.

“The real question is not whether these cities shrink – we’re all shrinking – but whether we let it happen in a destructive or sustainable way,” said Mr Kildee. “Decline is a fact of life in Flint. Resisting it is like resisting gravity.”

This is the type of neighborhood that the government wants to disurbanize. It is located in central Detroit.

Detroit Demolished

To someone trapped in the mindset of development and control that we have practiced in the 20th century, a place like this is a nightmare. It is not possible to consolidate properties in order to bring in a large developer and a large bank that will finance “re-development” of the place. Worse yet, properties have been abandoned randomly, turning what were neat row houses with identical lots into a pockmarked landscape of randomly-sized public land chaos. Better to demolish everything and start over.

There is another mindset through which to interpret such a neighborhood, that of complexity. If we embrace complexity, then the randomly sized pockets of open land are an exceptional opportunity to renew the city of Detroit. They form a fractal solution set to new construction that many different people can participate in and contribute to. It can accomodate small, medium-size and eventually large-size businesses in close proximity with diverse housing and convenient transportation structures.

But why has this not worked for Detroit? Because its process of growth has not been focused on fractal scales but only on big projects and big businesses. Now that the big businesses are dying the city is threatened with disappearing and has to beg even bigger governments to prevent their death. That cannot go on forever. Death is a normal, natural process, and big businesses disappearing should never be a threat to a large city. The economic fabric of a city must always be renewed by new businesses. It is this renewal that creates a sustainable business ecology. At some point Detroit stopped the process of new business creation, and from then on its decline was assured.

Instead of demolishing its remaining neighborhoods and surrendering to the decline and death that will surely follow in its reduced form, Detroit should instead adopt the process of a special economic zone in those neighborhoods it wants to return to “nature”. Tolerate people build as they wish and let a slum happen, and from the slum will emerge the businesses that will renew Detroit’s economy. It can’t be worse than the bulldozer.

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Review of Home by Yann-Arthus Bertrand

June 9, 2009 · 6 Comments

I often wonder if it would be possible to do any kind of serious study into urban morphology without the help of Google Earth. I know it has been indispensable to my studies, perhaps as indispensable as the microscope is to biologists. Google Earth is our macroscope, it allows us to see what is too large to see with the naked eye. But no matter how useful satellite photography is, you cannot truly see depth without aerial photography, and the master of aerial photography is without a doubt French photographer Yann Arthus-Bertrand, famous for enormous coffee-table books filled with photography so rich as to be overwhelming.

Arthus-Bertrand has made the jump to high-definition cinematography and directed a “documentary” (there is really no accurate way to describe this film) called Home, which was released free of charge on the Internet a few weeks ago. You can watch it on YouTube or download it from your favorite BitTorrent source. The film is awe-inspiring. Here are some still images I extracted.

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The film is a tour of Earth’s ecologies, starting from elementary life to cities. The most striking images are those of natural cities, particularly one which seems to grow out of the rock as if it were only a feature of it. And who can argue that it isn’t? But that detail seems to escape the narrative.

Yann Arthus-Bertrand’s talent is undeniable, at some point in the film he even makes Manhattan seem small. But the film quickly turns into a vessel of green propaganda (sponsored by the Gucci fashion house) while it could have been a celebration of mankind’s ties to nature. At the climax of its alarmism, the foundation of the green mindset is spelled out with as much emphasis as the narrator can apply. Denouncing the thaw of Siberian permafrost, the narrator recites “if the permafrost melts, the methane released would cause the greenhouse effect to race out of control with consequences no one can predict.” At no point in the film does the alarm in her voice sound so grave. It is not so much climate change that is feared, but the unknown, any change at all.

The obsession with control and prediction is tragically what has caused the most destruction and chaos in our human ecologies. It is control that dictates that homes may not be owned in the world’s sprawling slums, in the name of upholding a failed prediction, city planning. Because slum homes can be summarily demolished the slums remain in squalid poverty, vulnerable to any environmental change, man-made or not. The only true sustainability in a chaotic world is the ability to renew our environments for any change we meet, and control and prediction are an obstacle to this.

Green politics fails not because it relies on facts that are incorrect, but because it relies on facts that are inherently unknowable. We can sound the alarm about the total global population, the fact is we have absolutely no idea what the total global population is. We can at best obtain an estimate, but that estimate is useless for any kind of action. Action in a complex system is local and does not rely on global knowledge, but only on reacting to local conditions. The environment always tells you what to be doing in the moment.

In its obsession with control, the film ends up making recommendations for creating the same kind of technocratic utopia that was promised to us by the modernists. It praises one of the world’s poorest countries for having one of the most intensive state schooling program, evading a causal link between poverty and control of children’s minds. The ultimate solution to climate change proposed is to cover the world’s open land with solar panels, and the seas with wind farms, an act that would be as destructive to the environment as all the other monocultures denounced in the film. (And no one dares ask where those solar panels came from.)

Never is a serious look taken at the process of the natural cities, which to someone trapped in the paradigm of control and prediction would make absolutely no sense, but which Christopher Alexander masterfully demystifies in The Nature of Order. Only through such a revolution can we avoid repeating the chaos of modernism with a green twist.

People trapped in the mindset of prediction cannot think beyond simple physical processes (type I and II of Wolfram’s classification). These processes are always highly unstable and prone to die with any disruption. But life is not a simple process. It is a process that is always expanding, growing exponentially to fill any space it can fit into. Biologists quarantined a volcanic island that appeared into existence in the 1960’s near Iceland. They wanted to see how life colonized it. This process has taken place at astonishing speed, and today the island teems with life and has a rich cover of top soil, bewildering the biologists. The real threat to the island is not ecological disequilibrium, but the inevitable erosion back into the ocean.

Life is the most powerful force in the universe. It will take anything the Earth does to it. But unless we adopt life as our own social paradigm, we will not fare well. If we base our society on control instead of growth, the first unpredictable shock we witness will cause our collapse. So watch Home, be inspired by it, but do yourself a favor and turn the sound off.

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Organization and intelligence

June 1, 2009 · 2 Comments

1. Sun Tzu said: The control of a large force
is the same principle as the control of a few men:
it is merely a question of dividing up their numbers.

2. Fighting with a large army under your command
is nowise different from fighting with a small one:
it is merely a question of instituting signs and signals.
- From The Art of War by Sun Tzu

The problem of social cooperation is how to order many individuals into large-scale patterns, and thus acquire the benefits of these larger patterns. The military arts were the first to face this problem, war being a field where inferiority carries severe consequences, and lessons are learned quickly. The solution was known in the time of Sun Tzu: the superior army was the one that could act as a single force, applying a single decision multiplied by however many men were at the command of this army. More men were always better, but past a certain scale it became unmanageable for a commander to yell out orders to everyone and maintain command. In order to resolve this the military men invented hierarchy, a command structure through which the commander’s orders would be distributed so that a group of any size could act as a single force.

For most of history success in war came from achieving and maintaining organization, lines of command from a center to the individuals that compose an army such that the commander could deploy the army in the most effective pattern he could think of. Discipline and complete obedience to orders was required, even if the situation as it appeared to the lowly grunt was in total contradiction to the orders he had been signaled. As far as he knew, the commander had a larger picture of the war and the orders ought to work out correctly. But the flaw in organization is that as an organization becomes larger, as the layers of hierarchy increase, the commander becomes more remote and more isolated from his army. The lines of communication become inefficient, the orders become irrelevant, and many men die stupidly.

Nevertheless, for centuries the sheer overwhelming force of numbers more than made up for the losses due to bad orders. The principle of organization triumphed. Reformers started looking for plans to organize industries, entire nations (the command economy of the Soviet Union), and of course, cities. The C.I.A.M. Athens Conference resulted in the publication in 1942, by Le Corbusier, of the Athens Charter, the document upon which the plans to organize modern cities, and be rid of the spontaneous historic city, were founded.

Between the time of the Athens Conference and the publication of the Athens Charter, the military concept of large-scale organization was completely discredited.

In June 1940 the German army invaded France. The two armies were evenly matched in men and weapons, France even having a advantage in tanks. Within one month the French army organization collapsed and millions of men surrendered without having put up much of a fight, resulting in many decades of American jokes about French surrender. In reality the two armies were far from evenly matched; the German generals had discovered a mean to overcome the weakness in the principle of organization, that it relied on a central, single commander. Their model of cooperation has been called Blitzkrieg, the lightning war, and its intent was to reduce the delay in receiving and sending the “signs and signals” of command by removing them. German commanders out in the field were given broad directives and trusted to figure out on their own how to fulfill them, with glory and medals as reward for success. The French had instead refined organization and bureaucracy into a precise art. Within days of breaching into France, autonomous German tank divisions destroyed the lines of communication of the French army and paralyzed the front-line units. It became impossible for it to act as a single force, never mind stopping an invasion.

The German system of directive command was in fact the universal principle of emergence applied to military action. Instead of building a hierarchy of orders to communicate the will of a central commander, the armies were organized in parallel, directed to respond to their observed context, a context which was itself produced by other units of the same army. Instead of deploying the intelligence of a single commander holed up in an office in Berlin, the German system linked the intelligence of all of its officers into a more effective super-intelligence that could see all of the battlefield simultaneously. The collapse of the French army was therefore inevitable. It was a case of one against many.

As already mentioned, war teaches quickly, and the allies eventually adopted a similar operations model to fight the war to victory. German operations theorists went on to design the structure of NATO’s European defense, a war that we fortunately never witnessed. Urban planners did not have to learn this lesson, and they opted to organize cities to ruin.

hierarchy-network

The network structure is often, incorrectly, called a “bottom-up” organization. My opinion is that this label makes no sense. There is no up or down in a network. There is neither bottom nor top. Those are descriptions that apply to hierarchies only. In a network actions happen horizontally, in parallel. Large-scale patterns are made up of links between those local actions, as seen in the figure above. Human intelligence, for example, cannot be explained as a collection of cells. It is the patterns formed by the links between these cells that is intelligent, and it is these patterns that allow us humans to be several orders of magnitude more complex than individual cells.

The paralysis inflicted on the French army organization was in parts self-inflicted. Longer chains of command involved delays in transmitting information (reports from the field), analyzing the information, planning a reaction and ordering the new deployment. The bigger the army became, the more paralysis it suffered. This organization was in much the same situation as the dinosaur who did not feel a hit on his tail because the nerves were too far from his brain. The bigger it became, the more exposed it was to a paralysis-focused attack.

It should not come as a surprise that what caused the death of cities is also self-inflicted paralysis. But the case of cities is much more tragic. The German operations model was novel and innovative, a radical improvement in military art. Cities, however, had always been emergent. They were the product of a spontaneous order, a phenomenon that was barely understood at the height of rationalist planning. What science did understand was organization. Since it was accepted as the pinnacle of science, no rational thinker could reject the new urban planning. The planners did not notice the hints: what they were organizing had not been a creation of anyone.

In a complex emergent system, the number of unique patterns scales up with the size of the system. (What some emergence commentators call “more is different,” another expression that makes no sense.) While an organization attempts to create a large-scale pattern to outmatch smaller patterns, a complex system is made up of both small and large patterns, in proportion to a power law, either nested together or juxtaposed randomly (a fractal). If an emergent system is intelligent, it will structure itself into patterns that no one had expected.

For centuries people had been accustomed to such patterns as the street of similar shopkeepers. Many streets in European cities bear the name of a particular trade, such as baker’s street or threadneedle street. But when cities passed a critical scale during the industrial revolution, a whole new pattern emerged: the central business district. An entire city within the city became the center of commerce, not simply specific streets next to residences. Although it appeared unexpectedly during the 19th century (the Haussmannian renovation of the Opera district of Paris was meant to create a neighborhood for the upper classes, but it became a business center immediately and has remained so ever since), a central business district came to be what a major city was all about. When planners set out to organize a modern city, they planned it around the CBD as the central feature. They did this by drawing a square on the map and applying a different set of rules to this square. Within a few years, their CBDs began dying. The small scale patterns nested within them had been zoned out.

In retrospect it was inevitable for an attempt at organization to severely interfere with urban processes, the principle of organization being a step down in complexity from the principle of emergence. Organization had a sinister advantage: it gave the planners the illusion that they could predict what the city was going to become. An emergent system cannot be predicted with precision. The very basis of its intelligence is that it has not yet been decided what it is going to do. Embracing an emergent system means accepting that patterns will appear that are beyond our comprehension. (In Wolfram’s terminology, the system is computationally equivalent to our own intelligence.)

By trusting their front line officers to run the war for themselves, the German general staff took a leap of faith that paid off decisively and confronted every opposing military with their crippling inferiority. I suspect the first modern city to give up on the principle of organization will trigger a similar revolution.

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A pattern language for New York streets

May 22, 2009 · 3 Comments

The New York City Department of Transportation has published its street design manual, a collection of patterns that make absolutely no references to any traffic control devices of any kind. This is the result of the revolutionary transportation commissioner and, let’s admit it, traffic anti-planner Janette Sadik-Khan (NYMagazine article on her rise) who has launched a mini-revolution since being appointed to run the street bureaucracy of New York City two years ago. Traveling around the world to learn what was being done the best, and falling under the influence of Jan Gehl along the way, she is the living proof that visionary leadership can turn even the most entrenched bureaucracy around.

You will notice that the manual distinguishes between ribbon sidewalks (totally useless) and full sidewalks (the bare minimum). In fact they couldn’t even find a picture of a ribbon sidewalk with people walking on it.

What this mini-revolution has meant is that the Department of Transportation has been abolished in all but name, admitting the reality that cities do not have transportation, they have spaces. It has also meant that the autocratic, yet highly productive, legacy of Robert Moses has made a comeback. Moses set out to transform New York into a city of the 20th century. Sadik-Khan is transforming his legacy into America’s first city of the 21st century, with the same initiative, inspiration and leadership, but with more human and sustainable ends to realize.

Thanks to the pro-urb list for the scoop. You can monitor New York’s street revolution in real-time on Streetsblog.

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The development model is finished

May 19, 2009 · 7 Comments

An interesting graph on the state of the housing subdivision industry in America posted at the Daily Reckoning.

This is the lowest rate of development since statistics began in the 1950’s, which is to say the time when the modern development system was created. A new model of urban growth is now not only a better idea, it has become a necessity. Only those communities that adopt emergent urbanism will get out of this crash, and hopefully they will adopt this new urbanism deliberately instead of being swarmed with squatter settlement.

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The Fundamentals of Urban Complexity

May 11, 2009 · 9 Comments

This is part II in an ongoing series of excerpts of an article set to be published this summer in The International Journal of Architectural Research, tentatively titled The Principles of Emergent Urbanism. Click here for part I, The Journey to Emergence.

The qualities of an emergent city

The adoption of mass-production processes, or development, in substitution for spontaneous urban growth in the mid-20th century created for the first time a phenomenon of alienation between the inhabitants and their environment. While the physical features of spontaneous cities could be traced to complex histories of families, businesses, and organizations, the physical features of planned cities owe their origin only to the act of planning and speculation. This has severe consequences towards the sustainability of place as there will not grow any particular attachment by the residents, their presence there being only a temporary economic necessity and not the outcome of their life’s growth. Mass-production of the environment left people as nothing more than consumers of cities where they used to be their creators. A building culture was replaced with a development industry, leaving the landscape culture-less and with no particular sense of identity. This took place despite the evidence that a building which has a unique history and has been fitted to someone’s life, as opposed to speculatively produced, generates market value for that property. (Alexander, 1975) This is why, although the demolition of so-called “slums” to replace them with modern housing projects created a great deal of opposition against urban renewal programs, the demolition of the housing projects later on did not lead to a popular preservationist opposition. They were not the physical expression of any culture.

In additional to cultural patterns, spontaneous settlements also have a peculiar morphology that has not successfully been imitated by modern growth processes. Spontaneous settlement processes give individuals full freedom to determine the boundaries of their properties. Spontaneous settlement is one where total randomness in building configuration is allowed, with no pre-determined property lines acting as artificial boundaries. Buildings and building lots as such acquire general configurations comparable to cell structure in living tissues, unique sizes and boundaries that are purely adapted to the context in which they were defined. In the absence of abstract property boundaries, property rights are bounded by real physical limits such as a neighbor’s wall. (Hakim, 2007)

Very attractive spontaneous cities have a specific pattern of the urban tissue. It consists of similar vernacular buildings that appear very simple when considered individually, but produce a visually fascinating landscape when considered as a whole. This is a form of fractal geometry. In mathematics a fractal is a geometric object of infinite scale that is defined recursively, as an equation or computation that feeds back on itself. For example the Sierpinski triangle is defined by three triangles taking the place of one triangle as in figure 4.

Sierpinski_triangle_evolution

Figure 4. A triangle triggers a feedback function that produces three triangles, which themselves trigger the feedback function to produce nine triangles, and so on. This process can unfold as long as computational resources can be invested to increase the complexity of the object.

The Mandelbrot Set is a much more interesting fractal that is defined as a simple recursive mathematical equation, yet requires a computation to visualize in its full complexity. When computing how many cycles of feedback it takes for the equation to escape to infinity for specific coordinates, figure 5 is the outcome.

Mandelbrotset

Figure 5. The image on the right is a deeper magnification of the image on the left, produced with a narrower range of coordinates as the input of the Mandelbrot set’s feedback function.

In addition to its remarkable similarity to natural phenomena, this form of geometric order informs us of a very important law in geometry: a feedback loop that is fed through the same function will produce an ordered but unpredictable geometric pattern out of any random input.

This tells us why cities of vernacular buildings have such appealing geometric properties at the large scale, despite being often shabby and improvised at the scale of individual buildings. Shanties made of scrap metal and tarp look rough at the scale of the material, but because multiple shanties share the construction process and originate from similar feedback conditions they form an ordered geometric pattern with its specific “texture”. The same process takes place at other scales of feedback, for example the production of a door. Whether the input for one door is larger, taller, wider than another door, if the same production process is employed the two doors will contribute to the overall fractal order of the urban space. This law has been employed not only in traditional and spontaneous cities, but also for modern urban planning initiatives. In the New York City neighborhood of Times Square the structure of billboard advertisements is defined by a building code that determines their configuration in relation to the configuration of the building. The outcome is a unique tissue of advertisement billboards that has become more characteristic of the neighborhood than the buildings themselves, which are not produced by a shared feedback function.

Fundamentals of urban complexity

Christopher Alexander showed in A City is not a Tree (Alexander, 1965) that social and economic networks formed complex semi-lattice patterns, but that people who observed them limited their descriptions to a simple mathematical tree of segregated parts and sub-parts, eliminating connections in the process. (Figure 6 compares the structure of a tree and semi-lattice.) In attempting to plan for urban structure, a single human mind, without a supporting computational process, falls back on tree structures to maintain conceptual control of the plan, thus computing below spontaneous urban complexity, a phenomenon that is consistent with Wolfram’s theory of computational irreducibility of complex systems. (Computational irreducibility states that the only accurate description of a complex system is the system itself and that no abstraction or reduction to a simpler process is possible.) Nikos A. Salingaros later detailed the laws of urban networks in Theory of the Urban Web. (Salingaros, 1998) Network connections form between nodes that are complementary, and therefore the complexity of networks depends on an increasing diversity of nodes. Salingaros describes the urban web as a system that is perpetually moving and growing, and in order to do this the urban tissue has to grow and move with it. Consider for example the smallest social network, the family. Debate over accessory units or “granny flats” has intensified as normal aging has forced the elderly out of their neighborhoods and into retirement complexes, while at the other end of the network young adults entering higher education or the labor market vanish from a subdivision, leaving a large homogeneous group of empty-nesters occupying what was once an area full of children, and often forcing school closures (a clear expression of unsustainability).

treelattice

Figure 6. A comparison of a tree pattern on the left and a semi-lattice pattern on the right. The tree structure is made of groups and sub-groups that can be manipulated separately from others. The semi-lattice pattern is purely random without distinct sub-parts.

These social networks grow more complex with increasing building density, but a forced increased in density does not force social networks to grow more complex. For instance the spontaneous settlements of slums in the developing world show remarkable resilience that authorities have had difficulty acknowledging. Because of squalid living conditions authorities have conducted campaigns to trade property in the slum for modern apartments with adequate sanitary conditions. To the authorities’ befuddlement some of the residents later returned to live in the slum in order to once again enjoy the rich social networks that had not factored in the design of the modern apartments and neighborhoods, demonstrating that the modern neighborhoods were less socially sustainable than the slums.

In commercial networks, space syntax research (Hillier, 1996), using a method for ranking nodes of semi-lattice networks, has shown that shops spontaneously organize around the multiple scales of centrality of the urban grid at its whole, creating not only commercial centers but a hierarchy of commercial centers that starts with sporadic local shops along neighborhood centers and goes all the way to a central business district located in the global center of the spatial network. The distribution of shops is therefore a probabilistic function of centrality in the urban grid. Because the information necessary to know one’s place in the hierarchy of large urban grids exceeds what is available at the design stage, and because any act of extension or transformation of the grid changes the optimal paths between any two random points of the city, it is only possible to create a distribution of use through a feedback process that begins with the grid’s real traffic and unfolds in time.

The built equilibrium

Although they may appear to be random, new buildings and developments do not arise randomly. They are programmed when the individuals who inhabit a particular place determine that the current building set no longer provides an acceptable solution to environmental conditions, some resulting from external events but some being the outcome of the process of urban growth itself. It is these contextual conditions that fluctuate randomly and throw the equilibrium of the building set out of balance. In order to restore this equilibrium there will be movement of the urban tissue by the addition or subtraction of a building or other structure. In this way an urban tissue is a system that fluctuates chaotically, but it does so in response to random events in order to restore its equilibrium.

This explains why spontaneous cities achieve a natural, “organic” morphology that art historians have had so much difficulty to describe. Every step in the movement of a spontaneous city is a local adaptation in space and time that is proportional to the length of the feedback loops and the scale of the disequilibrium. For spontaneous cities in societies that experience little change the feedback loops are short and the scale of disequilibrium small, and so the urban tissue will grow by adding sometimes as little as one room at a time to a building. Societies experiencing rapid change will produce very large additions to the urban tissue. For example, the skyscraper index correlates the construction of very tall buildings with economic boom-times, and their completion with economic busts. The physical presence of a skyscraper is thus the representation of a major disequilibrium that had to be resolved. (Thornton, 2005) The morphology of this change is fractal in a similar way that the movement of a stock market is, a pattern that Mandelbrot has studied. In general we can describe the property of a city to adapt to change as a form of time-complexity, where the problems to be solved by the system at one point in time are different from those to be solved at a later point in time. The shorter the time-span between urban tissue transformations, meaning the shorter the feedback loops of urban growth, the closer to equilibrium the urban tissue will be at any particular point in time.

Modern urban plans do not include a dimension of time, and so cannot enable the creation of new networks either internally or externally. They determine an end-state whose objective is to restore a built equilibrium through a large, often highly speculative single effort. They accomplish this by creating a large-scale node on existing networks. In order for such a plan to be attempted the state of disequilibrium in the built environment must have grown large enough to justify the immense expense of the new plan. This is why development will concentrate very large numbers of the same building program in one place, whether it is a cluster of 1000 identical single-family homes or a regional shopping mall, just like the skyscraper concentrates multiple identical floors in one place. Demand for these buildings has become so urgent that they can find a buyer despite the absence of local networks, the standardized building plan, or the monotonous setting. This is not as problematic for large cities for which a single subdivision is only a small share of the total urban fabric, but for smaller towns the same project can double the size of the urban fabric and overshoot the built equilibrium into an opposite and severe disequilibrium.

The mixed-used real estate development has attempted to recreate the sustainable features of the spontaneous city by imitating the morphology of sustainable local economic networks. It has not reintroduced the time dimension in economic network growth. Often this has resulted in a commercial sector that serves not the local neighborhood but the larger region first, consistent with the commercial sector being a product of large-scale economic network disequilibrium. In other developments the commercial sectors have struggled and been kept alive through subsidies from residential development, which is evidence of its unsustainability as part of the system.

References

Alexander, Christopher (1965). ‘A City is not a Tree’, Architectural Forum, vol. 122 no. 2
Alexander, Christopher (1975). The Oregon Experiment, Oxford University Press, USA
Hakim, Besim (2007). ‘Revitalizing Historic Towns and Heritage Districts,’ International Journal of Architectural Research, vol. 1 issue 3
Hillier, Bill (1996). Space is the Machine, Cambridge University Press, UK
Salingaros, Nikos (1998). ‘Theory of the Urban Web’, Journal of Urban Design, vol. 3
Thornton, Mark (2005). ‘Skyscrapers and Business Cycles,’ Quarterly Journal of Austrian Economics, vol. 8 no. 1
Wolfram, Stephen (2002). A New Kind of Science, Wolfram Media, USA

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Squatter urbanism comes to America

April 26, 2009 · 25 Comments

In previous posts I argued that the only way a modern housing subdivision was possible was by the creation of a permanent, extreme housing crisis by the authorities attempting to control development. Now this housing crisis is catching up with American cities and a phenomenon that was until then limited to dysfunctional third world countries, squatter camps, is popping up all over the country.

From the well-kept interior of the Caros’ place, one can hardly see the jagged rows of tents and shanties on the vacant land around them. About 200 people have built informal habitats along the railroad tracks, primarily poor whites and migrant workers from Mexico.

There are many names for this fledgling city, where Old Glory flies from improvised flagpoles and trash heaps rise and fall with the wavering population. To some it’s Little Tijuana, but most people call it Taco Flat.

Just to the south, under a freeway overpass, there’s another camp of roughly equal size called New Jack City where most of the residents are black. Even more dwellings are scattered throughout the neighborhood nearby, appended to the walls of industrial buildings and rising up the flanks of freeway spurs.

Fresno, which the Brookings Institution ranked in 2005 as the American city with the greatest concentration of poverty, is far from the only place where people are resorting to life in makeshift abodes. Similar encampments are proliferating throughout the West, everywhere from the industrial hub of Ontario, Calif., to the struggling casino district of Reno, Nev., and the upscale suburbs of Washington state.

In any other country, these threadbare villages would be called slums, but in the U.S., the preferred term is tent city, a label that implies that they are just a temporary phenomenon. Many journalists, eager to prove that the country is entering the next Great Depression, blame the emergence of these shantytowns on the economic downturn, calling them products of foreclosures and layoffs.

While there’s some truth to this notion, the fact is that these roving, ramshackle neighborhoods were part of the American cityscape long before the stock market nosedived, and they are unlikely to disappear when prosperity returns. The recent decades of real estate speculation and tough-love social policies have cut thousands of people out of the mainstream markets for work and housing, and the existing network of homeless shelters is overburdened and outdated.

People such as the Caros are part of a vanguard that has been in crisis for years, building squatter settlements as a do-or-die alternative to the places that rejected them. This parallel nation, with a population now numbering in the thousands in Fresno alone, was born during the boom times, and it is bound to flourish as the economy falters.

“The chickens are coming home to roost,” said Larry Haynes, the executive director of Mercy House, a homeless outreach organization based in Southern California. “What this speaks of is an absolute crisis of affordability and accessibility.”

…

In Fresno and other struggling cities, which perpetually strive to boost tax revenues with development, tent cities are often seen as symbols of criminality and dereliction, glaring setbacks to neighborhood revitalization efforts. That perception is common wherever informal urbanism exists, said Mehrotra, and it often leaves squatter camps on the brink of ruin.

“You are always on the edge of demolition,” Mehrotra said. “There’s a kind of insecurity in the lack of tenure on the land.”

This hit home in Fresno a few years ago, when workers began raiding encampments throughout the city, tearing down makeshift homes and destroying personal property in the process. The city of Fresno and the California Department of Transportation conducted these sweeps in the name of public health, citing citizen complaints about open-air defecation.

Yet the raids did nothing to stop tent cities from forming, and they ultimately led to lawsuits. In October 2006, residents who lost their homes in the raids filed a class-action suit against the city of Fresno and the state of California. A U.S. district judge ordered the defendants to pay $2.3 million in damages.

Tarp Nation – High Country News

The same features that define the process of every squatter town are present. There is the random occupation of land, the lack of any amenities, and of course the police repression that makes it impossible to create a viable economy. As the public authorities run out of money they will have to lighten the repression and the squatter towns will move into the second class, one with fixed buildings and small outlaw businesses that will attract even more of the poor looking for subsistence. They will become America’s Dharavis.

Instead of using repression to enforce a planning system that drives people into destitution, the authorities should instead act pre-emptively by extending the towns’ infrastructure ahead of urbanization, not in collusion with home builders, and tolerating that the settlers build themselves out of poverty, something that they know quite well how to do. Over time these neigborhoods would go through an unslumming process, and their social and economic liveliness would make them even more attractive than subdivisions, at which point they may become historic cities the likes of which people always built before the modern planning process. The people who were once destitute would be small-time property developers and landlords, and for those who still had nothing the process could be repeated in a new neighborhood.

Update: Here are some pictures of the “Hoovervilles” that sprung up in America during the 1930’s.

hooverville-154

hooverville1ashx

The beginning of a real place.

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A conversation about the geometry of nowhere

April 12, 2009 · 7 Comments

In response to my last article, Bruce Liedstrand of Community Design Strategies in Paris writes,

I read with interest your essay on The Geometry of Nowhere because I divide my time between Paris and Silicon Valley (the site of your Cupertino Target store example). After re-reading the essay, I am puzzled. I hear your frustration with narrow sidewalks, but I am lost in understanding your concept of “place”.

My experience has been that a “place” is created by spatial enclosure, the use of adjacent buildings to enclose and shape the space into a comfortable “place”.  Paris is strong on spatial enclosure. To me it seems almost as if Paris started as a solid mass and that the boulevards were carved out of the mass by broad blades and the narrower streets (“rues”) by finer blades. Wherever I am in Paris I feel comfortably inside a good place.

Your essay seems to indicate that “place” exists without any enclosure by buildings. That, indeed, it can exist on the outside edge of buildings rather than inside a group of buildings. Is that what you intend?

I am puzzled also by your discussion of the Cupertino Target store, which I have personally visited. (Ed note: What are the odds?) When I look at your illustration of your changes, I don’t see any “place”. What I see new is open spaces outside buildings from which cars have apparently been excluded. Do you intend to say that exclusion of cars is the key to converting undifferentiated open space into a good “place”? What is it about these new open spaces around the store that would make them comfortable for people to linger in?

Perhaps I am reading your essay wrong? Can you please point me in the right direction?

Thanks.

Enclosure creates a room, but it’s not sufficient to create a place. You can see this in Paris, where some of the best places in the city are not enclosed, for example along the Seine, or the Luxembourg garden. And the most enclosed places, like Place Vendôme, are not very interesting.

To get a good understanding of the relative impact of enclosure and open space on place, all we have to do is take a long walk along the axe historique. Start at Place de la Concorde, which was about 50% sidewalk 50% free space when it was created and is not enclosed. All the free space was converted to road and now it is perilous to get across, but still a place. Walk down to Rond-Point de l’Élysée through a wood with substantial open space to walk across. I don’t know if that counts as enclosure, but it’s a good place. Then you have the model of place, the Avenue des Champs-Élysées with its straight-aligned buildings, that is also a place with 50% sidewalk and 50% road. And it is a major road, 10 lanes of traffic, but that doesn’t really interfere with it as a place because there is little reason to cross the road, and it can be done in two steps thanks to traffic islands.

Once you’re up the hill and you go across the monster Place de l’Étoile (horrible place, all cars driving maniacally so that pedestrians have to cross in underground passages), you end up on Avenue de la Grande Armée, which is morphologically identical to the previous avenue except that some of its space is taken by parking lots. That means the ratio of sidewalk to road is much less than 50/50. It’s also much less crowded and much less attractive than the previous avenue, but it still works.

After you get across Porte Maillot to Avenue Charles de Gaulle in Neuilly, then you find the same buildings with the same alignments and the same enclosure as the two previous avenues, except this time the space has been traffic-engineered to hell, combined with speed cameras to dissuade speeding. What space there was on Grande Armée has been cut even further, and the result is a dead street on what is a major business center of the city.

Finally cross the bridge and climb your way up to the Parvis de La Défense, where you will find that the buildings are modern and completely random, but the space is fully open to people and always full of people. (Even on Sundays!) I interviewed the master planner for the northern expansion, and he said the developer of La Défense did not agree to build the 25m wide pedestrian bridge he had designed to connect the site to the main place. After their small “passerelle” failed they backed down and built the full bridge, and it works, always full of people.

So there you have it, the closest thing to a controlled experiment on place and enclosure. Enclosure turns out to be irrelevant.

Have a nice walk.

Do you really find La Defense a pleasant place?  For me, it is utterly placeless – one of the worst locations in Paris?

If you have extra time on a pleasant afternoon, would you really rather spend it sitting in the open space of La Defense than in my neighborhood park?

p1010675_4

La Défense is a business place, and it works at what it is. But compared to Avenue Charles de Gaulle, which is another business place, and which has the same architecture and alignments as the rest of Paris, it is a much better place.

Can you say this is not a good place?

Look at all the people. They’re not locked up in their offices. The neighborhood is set up so you can go straight to your office to the metro using tunnels, but when I was there I always preferred taking a detour on the surface. Take my word for it, people even go there on the weekends to teach their kids how to ride bikes and roller-skate. They don’t care that the buildings aren’t aligned.

What I am asking with my article is how can we reduce and remove sprawl without going through an expensive process of total demolition for which we won’t have the money anymore? We don’t have the choice of your small neighborhood park. A place and a park are very different things anyway. Cities existed for centuries without parks, but never without place. If we reintroduce place in sprawl cities, that means shops that rely on place to survive don’t have to open up in the mall anymore, they can do business anywhere because the entire city is a mall (one of the first things I realized about Paris). Then your city starts to grow around place instead of around roads, and people have a reason to linger.

Yes, for me it is not at all a good place in the photo or in personal experience.  People are dwarfed by the size of the space (in the photo, the space is almost empty) and it is not comfortable.  One can look at the buildings as perhaps interesting objects, depending on one’s taste, but it certainly is not a place I would linger in or return to regularly if I didn’t work there.Let’s accept that we disagree, vigorously, about whether La Defense is a good place.  But what, in your view, makes a good place.  So far I hear you favor an absence of cars and openness?  Is that right?  Is that all, or can you tell me more?

And what would be good about your redesigned Target store?

I didn’t redesign the Target store, I left it there as a necessity of the context, and the people at La Défense aren’t looking at the buildings. They’re a necessary part of the décor, but they’re not the reason people use the place, or any place.La Défense became a success, despite everyone’s intent, because economic conditions forced the developers to break the master plan and allow any random building to be built. Had they not done so it would be exactly like Empire State Plaza in Albany. The difference between the two is not architectural, it is socio-economic.

You do not need to remove cars to make a good place, you only need to remove the exclusivity for cars. What makes a good place is total freedom of movement for everyone, including the freedom to stop and linger. You can’t do that in traffic engineered space because you are confined between very narrow limits. They tell you how fast to go, when to stop, where to turn, it’s a nightmare, but one that we put up with to go fast.

Is an empty space out in the desert a good place because everyone can move freely?  Or are you talking about places within cities?  Is it just traffic engineered spaces that you reject?  Are you advocating a Hans Monderman approach to streets?  Are you rebelling against “confinement”, or is some broader principle involved?

I agree that the Empire State Plaza in Albany is a terrible place.  Are you saying that the only problem with it is that, unlike La Defense, the buildings are not place at random?  What do you mean by saying that the difference is “social-economic”?

Could you please write in one paragraph what you believe are the key factors in creating a good place within a city so I can understand where we might agree or disagree?

Deserts can make a good place, although there is not much desert urbanization. (Desert driving is a lot of fun nevertheless.) Open space alone does not make a place, you also need people there, and the reason that people go through any place is to participate in and generate social and economic networks. This was not done at Empire State Plaza but was done at La Défense.

The issue is at core about freedom. How much freedom of movement do I enjoy, how much freedom to grow and build do I enjoy? In a place you can walk anywhere and build anything anywhere, or just occupy the space to conduct some activity like playing hockey or learning to ride a bike. That creates networks and attracts people. In sprawl the entire space is traffic engineered. To move around you are practically on a conveyor belt, offered only a linear path, delimited speed and a select few choices. You can’t build anything because of the zoning. The choices available to you have been selected by the traffic engineers and the planners, and they only fit  their model of what they want you to do. There is no creativity possible to invent your own journey. A famous game designer once said “a game is a series of interesting choices.” What kind of choices does sprawl offer?

The one place in sprawl where people are given a shred of creativity is the mall, and that’s how people who live in sprawl spend their free time. You can go there and just hang out, inventing an activity from nothing. It’s all the place they have left.

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