The manifesto of the Emergent Urbanism Network

As the idea of an emergent urbanism has become more popular, I’m receiving more and more emails asking me to look over some link or another and provide an opinion of the content. As I have unfortunately limited time, I cannot answer many of these requests. This led me to the realization that this little website needs to take a new, bold step into becoming something more than a blog/lesson, into an experiment in a new type of media.

When Le Corbusier set out to transform the world in his image, he did so by publishing his own magazines and books so that he would capture the imagination of humanity with all the power of the new forms of mass media, something that the traditionalist architects did not see any value in. It was his power to communicate farther and with more voice than any other that made him a legend. Despite all of our technological progress, we still experience the same form of mass media that Le Corbusier pioneered, and with mass media has come naturally the process of mass planning and mass architecture.

If there is to be a revolution towards a rediscovery of the more natural, more individual and more emergent forms of urbanism, there must also be a revolution in the media of urbanism. What is needed is not simply a change in form but a change in process all-around. The beginning of this change is a new way to communicate.

As social media networks have developed over the last few years (and it has taken very few years for them to stake their place alongside traditional mass media) we have rapidly accustomed ourselves to reading about only those things we find most relevant to our own perspective on the world, yet the information that is most relevant is spread out over myriad blogs, social feeds, and search engines. Those portals that do set out to provide news in urbanism rely on antiquated centralized editorial review processes to tell us what we should be interested in, in the same way Le Corbusier edited his magazine.

It is with these concerns in mind that I set out to design the Emergent Urbanism Network, a pioneering social media portal that aims to deliver to you the knowledge you need to advance your own personal growth as well as contribute to the growth of your peers. It is a portal that you create and you structure, in combination with every other member, into a publication that is infinitely scalable. It is an emergent form of media advocating for an emergent city.

If you are reading this, it means that you have become urgently interested in the subject of emergent urbanism. You may be a planner, an architect, a computer scientist, a consultant, an urbanist, an economist, a journalist, or anything else. Regardless of your title, your depth of interest is what matters most. Your contribution in the beginning of this new venture is critical, as it is the early structure you provide to the network that will shape its future. I need you to connect immediately and start telling us all about the issues and events you feel are related to urban complexity and emergence. You will help each other and you will help me as I continue to develop the technology to create the most powerful urban portal on the Internet.

Thank you all for your curiosity and your contributions. I’ll see you on the other side.

Emergent Urbanism at the University of Montreal

I was invited to the complex systems laboratory of the Université de Montréal this week to present emergent urbanism to their twenty-member large research group. Click through to SlideShare in order to see the full text of the presentation under the “notes on” tab. The entire text is in French, however I know a significant share of this website’s visitors enjoy French once in a while.



If someone wants to sponsor me for a translation in English, email me and I’ll upload one very soon. Otherwise my hands are quite full at the moment, it might be a while before I get around to it.

Thanks to Rodolphe Gonzales from the Complex Systems Lab for the invitation. You can read about their work here.

Fake complexity: traffic control

The University of Minnesota Center for Transportation Studies Intelligent Transportation Systems Institute has produced a handy little flash game where you can experience the life of a traffic planner in a series of increasingly complicated traffic challenges.

The game begins in the Stalinian Central Bureau of Traffic Control, where a wrinkly old man pulls you out of your job at the mail room to come save the traffic control system. You are brought to a space command-like control room and put to work setting traffic lights to stop and go. Meanwhile frustrated drivers stuck in the gridlock you create blare their car horns to get your attention, and if their “frustration level” rises too high you fail out of the level. As the road network gets as complicated as four intersections on a square grid, the traffic becomes completely overwhelming and failure is inevitable, but the old man reassures you that they too have failed anyway.

It’s hard to tell where the joke begins and where it ends with this app. According to the ITS news feed the game’s purpose is to let “high school students try their hand at working in the engineering and transportation field.” And, as if astonished by their own profession’s ridicule, the game’s description of the traffic control room reads “the traffic control center in the game is realistic: many large metropolitan areas (such as New York, Boston, and the Twin Cities) have traffic control centers that actually do look like that.”

You must play it and experience it for yourself.

Why was this made? Are traffic engineers passively crying out for someone to put them out of their misery? Traffic, after all, is the most complex pattern of all those that compose a city. While buildings move around over the span of years, traffic consists of thousands to millions of randomly moving parts in the span of a day. Despite all the efforts that have been invested in designing traffic control devices, the “frustration level” for drivers has only risen.

Some traffic engineers have learned that the problem was not traffic but central planning, the foremost of which was Hans Monderman. By running a driving school and studying how people related to their environment, Monderman discovered that the traffic control devices the profession employed were not only useless but counter-productive. He set out to remove traffic control and empower drivers to control themselves and make decisions based on their context. His model for traffic control is to design the context so that drivers will control themselves and each other, a scheme called shared space.

The basis of an emergent intelligent system is that individuals act and make choices based on a shared system of contextual rules. This decentralizes decision making and makes possible the optimal adaptation to chaotic environments. We can see this in the superior performance of the roundabout as compared to the traffic light for traffic flow. A roundabout is a rule that tells drivers to yield to other drivers coming from other directions. It is decentralized. A traffic light simply tells drivers when to stop and go, whatever the situation may be at the current time. When the traffic light status becomes completely alienated from reality, gridlock occurs and frustration boils. What frustrates drivers is their powerlessness to contribute to the intelligence of the system, and the utter waste of time being imposed on them because of traffic planners unfamiliar with the precise circumstances taking place.

It should be no wonder then that when the traffic control system fails, traffic flows better.

The Intelligent Transportation Systems Institutes of this world are trying to create intelligent traffic control tools, but those are another form of fake complexity. When all drivers, cyclists and pedestrians are optimizing their behavior based on simple traffic rules, that is when traffic becomes intelligent.

(The scoop on this was obtained from Streetsblog and TransitMiami.)

Related topics

• The geometry of nowhere

Principles published

The full article conceptualizing the principles of emergent urbanism has been published by the International Journal of Architectural Research volume 3 issue 2. You can download the complete article or read the whole issue.

The Cultivation of a Spontaneous City

This is the last of a series of excerpts from my article in the upcoming issue of the International Journal of Architectural Research, about the principles of emergent urbanism. Click here for part I, The Journey to Emergence. Click here for part II, The Fundamentals of Urban Complexity.

How emergent urbanism works

In a traditional spontaneous city, 100% of the surface is initially a network structure, open land. From this surface the best paths are selected to fit the networks that are emerging, and the leftover space is progressively built upon. Starting with a completely open, fully-connected land structure, the city’s design can consist of a purely negative process by placing constraints on construction over important paths. In this way the street structure and hierarchy becomes an evolved structure that matches the history of its networks, and the placement of buildings and uses is also an evolved structure that matches the flows of movement. Over time these paths are paved and upgraded, and important junctions of paths become the central open space of the city. The central square of a spontaneous town can be explained as the remainder of a fractal process of subtraction, with the most underused part of the spatial network being removed at each additional step of feedback until no further network subtractions are possible. With the circulation of people optimized, the remaining space is augmented with street furniture specifically designed for crowds, such as benches, transit stops, billboards, kiosks and so on.

An emergent city similarly begins with a network structure, although one that is much more sophisticated than open land. In modern design the typical asphalt street produces a network that is suited particularly to automobile networks, but also has the unfortunate side-effect of cutting pedestrian networks that normally enjoy the entire surface in a spontaneous city. As a remedy these streets are equipped with sidewalks that are often narrow and unpleasant (if not dangerous) to walk, an effort at translating strict traffic control methods to the pedestrian. It is not surprising that pedestrians are so rare in modern cities, but some efforts have shown that pedestrian networks can emerge from modern design. One example is the three-story deck of the La Défense business city in Paris (shown in figure 7), which contains parking but also regional rail and subway links, as well as being an open pedestrian surface. At the ends of this network structure a generative process of spontaneous development creates the actual networks of the city. As evidenced by the crowds present on that surface and the abundance of neighborhood shops the pedestrian networks function quite well. What is more surprising is that the automobile networks are underused and some parking structures empty, despite the neighborhood having been conceived for the automobile.

Figure 7. The “pedestrian slab” style of design was blamed for the failure of modernist urban planning projects, but at La Défense the slab is a working structure. The developer adopted spontaneous building development instead of applying the complete architectural plan, enabling the formation of a dense local economy.

Because of the high costs and other complexities involved in producing networks for modern transportation systems it is not possible to practice a purely negative and subtractive process of street formation. However the network structure must still be an evolved structure that is produced with feedback from lot development instead of building an entire grid before it has been decided what size of lot is needed. Most importantly all forms of movement must be in balance in the street design so that one type of network structure does not cut another and prevent the network formation process. (Salingaros, 1998)

The cultivation of a spontaneous city

Once a network structure is in place the process of network formation can begin.

Wiki systems have shown that simple freedom to create does not necessarily produce networks unless there also exists a simple interface to this network. The World Wide Web provided a system of linked websites that could spontaneously produce an encyclopedia for many years before the Wikipedia system catalyzed the distributed knowledge of millions of people into an exponentially growing and internally coherent system. The creation of crowd-catalyzing systems has since been named “crowdsourcing.” Translating crowdsourcing principles to planning processes, Alexander described in The Oregon Experiment how an institution could directly support the spontaneous development of its city by providing designers and managers to assist individuals and realize the program that the individual users have in mind. (Alexander, 1975)

With the initiative for developing new building programs left deliberately undefined and in the hands of the individuals and organizations that develop the socio-economic networks of the city, there remains the issue of producing a geometrically coherent landscape that is harmonious and distinctive. This is accomplished with shared generative processes, (Alexander, 2004) and particularly the nesting of generative processes into one another (also known as a shape grammar or form language), as shown in figure 8.  No matter what configurations of space are required by any individual building program, if this configuration is realized physically by the same building process as for any other random configuration then the two realized buildings will share symmetric properties and the result will be a harmonious geometric order. This has been employed in many instances by the regulation of construction materials, which creates a geometric order at the scale of texture, but it also applies for any other scale of geometry, as evidenced by the geometric order created by the advertisements in Times Square.

Figure 8. Three volumes are randomly defined in space without relation to each other. When a shared feedback function is applied to transform these volumes the volumes become related by these transformations. The function in this case is: 1 – Cut out the top corners to half the volume’s height, 2 – Raise the center of the roof.

By defining construction processes instead of fixed building designs it is possible to plan for future growth without eliminating spontaneous growth and feedback. A developer that is initiating a program of emergent urbanism can therefore prepare for construction in advance of any projects having been determined. Building high-technology structures is a complex art that requires significant expertise and a skilled workforce. The developer that creates adaptive building processes that can be used to generate and realize building plans easily and rapidly will provide the same spontaneity as squatter settlements achieve.

As evidenced by the popularity of historic towns of Europe and particularly the Mediterranean as tourist destinations there is enormous demand for and profit to be made from cities that adopt the geometry of emergent cities. For this to work however the development and banking industries must be persuaded of the effectiveness of process design as opposed to master planning, and the municipal authorities must be willing to approve urban design with no fixed configuration. (Alexander, 2004) Political issues also create a significant obstacle. The long approval processes that one must go through to develop a new city or neighborhood have significantly increased the length of the feedback loops and favored large-scale development as well as made small communities less competitive. Even when long review or public consultation processes can be avoided, a development has to comply with weighty subdivision and building codes that consume time to absorb and understand, and in so doing contribute to lengthening the feedback loops and making the urban tissue less adaptive and less sustainable.

References

Alexander, Christopher (1975). The Oregon Experiment, Oxford University Press, USA
Alexander, Christopher (2004). The Process of Creating Life, The Nature of Order Vol. 2, Center for Environmental Structure
Salingaros, Nikos (1998). ‘Theory of the Urban Web’, Journal of Urban Design, vol. 3, also in Chapter 1 of PRINCIPLES OF URBAN STRUCTURE, Techne Press, Amsterdam, Holland, 2005.

Modeling the processes of urban emergence

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.

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.

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).

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.

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.

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.

Organization and intelligence

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.

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.

The Journey to Emergence

This is part I of a series of excerpts of an article to be published in the International Journal of Architectural Research entitled The Principles of Emergent Urbanism. Additional parts will be posted on this blog with the editor’s permission until the complete article appears exclusively in the journal’s upcoming issue.

Of the different domains of design urban design is an oddity. While the design of a machine can be traced to a definite, deliberate act of invention, and even the design of buildings (architecture) is rooted in known production processes, the design of cities was never seriously attempted until well after cities had become a normal, ordinary aspect of civilized living, and while the design of machines and buildings was a conscious effort to solve a particular problem or set of problems, cities appeared in the landscape spontaneously and without conscious effort. This places the efficacy of urban design in doubt. The designers of machines and buildings know fully how the processes that realize their design operate, and this knowledge allows them to predictably conceive the form they are designing. Urban designers do not enjoy such a certainty.

How is it possible for what is obviously a human artifact to arise as if by an act of nature? The theory of a spontaneous order provides an explanation. According to Friedrich A. von Hayek (Hayek, 1973) a spontaneous order arises when multiple actors spontaneously adopt a set of actions that provides them with a competitive advantage, and this behavior creates a pattern that is self-sustaining, attracting more actors and growing the pattern. This takes place without any of the actors being conscious of the creation of this pattern at an individual level. The spontaneous order is a by-product of individuals acting in pursuit of some other end.

In this way cities appear as agglomerations of individually initiated buildings along natural paths of movement, which originally do not require any act of production as dirt paths suffice. As the construction of individual buildings continues the most intensely used natural paths of movement acquire an importance that makes them unbuildable and these paths eventually form the familiar “organic” pattern of streets seen in medieval cities. This process still takes place today in areas where government is weak or dysfunctional, notably in Africa where urban planning often consists of catching up to spontaneous settlement, and in the infamous squatter slums that have proliferated in the 20th century.

A transect of the city of Tultepec in Mexico provides a snapshot of the different phases of spontaneous urban growth. (Google Earth image)

As urbanization becomes denser, the increasing proximity of concurrent, competing individual interests causes conflicts between the inhabitants of the emerging town. Individuals build out their properties in such a way that it interferes with others, for example by blocking paths or views. These acts threaten the sustainability of the spontaneous order, and to resolve this situation the parties involved appeal to the same judges that rule on matters of justice. These judges, again according to Hayek, are required to restore and preserve the spontaneous order with their rulings. These rulings provide the first building regulations and, when government authority becomes powerful enough to do so, are compiled into comprehensive building codes to be applied wherever the force of that government extends. (Hakim, 2001)

The compiled building codes are later brought by colonists to create new settlements, reproducing the morphology across multiple towns but each time in a pattern that is adapted to the local context. Early town planning efforts are attempts at regularizing the building codes in order to plan for long-term organization of cities, but maintain the spontaneous production process. Most notably the rapid urbanization of New York City was accomplished by very simple rules on the size of blocks laid out in the 1811 Commissioners Plan for New York. Unlike the experience of urbanization in previous centuries, where urban growth was slow and often stagnant, the urbanization of New York took place in a time of rapid social and economic changes, and the city government had to invent building codes involving issues that never could arise in a pre-capitalist society: first the tenement, then the skyscraper, and ultimately, the automobile.

Modernism: the replacement for the spontaneous order

Architects and urban planners of the early 20th century, confident in the techniques of engineering and industrial production, believed that the spontaneous city had become irrational and had to be replaced with a new design fully integrating new industrial technology. The Swiss architect Le Corbusier is famous for designing a complete city around the automobile and building models of his design. In so doing he adopted a process of urbanization that was completely planned hierarchically, applying the processes familiar to architects at the scale of an entire city. He also ridiculed the morphology of spontaneous cities as being the product of donkey-paths.

This scale model of Le Corbusier’s Plan Voisin marks the turning point where city plans as constraints on individual initiative are replaced with architectural design at the scale of millions of inhabitants. (Le Corbusier, 1964)

Although the architectural program of high-rise living of Le Corbusier was discovered to be a colossal failure, the modernist process of development replaced spontaneous urbanization in the industrialized world. The housing subdivision substituted adequately for the high-rise tower block, providing affordable housing in large numbers to a war-impoverished society. This production process is still in force today, separating cities into three distinct zones: residential subdivisions, industrial and office parks, and commercial strips.

Modern city planning has been successful at its stated objective, producing a city designed specifically around automobile use, yet it was immediately and has been perpetually the target of criticisms. Most significantly the vocabulary of these criticisms had to be invented in order to spell out the critics’ thoughts because the type of deficiency they were observing had never been seen. Words like placeless or cookie-cutter were invoked but fell on the deaf ears of urban planners who were trained in Cartesian processes and industrial production techniques.

The most devastating criticism of modernist urban planning came in the form of a sociological study and personal defense of the spontaneous city, the book Death and Life of Great American Cities by Jane Jacobs. (Jacobs, 1961) In it she described in great details how the functions of a spontaneous city related and supported each other. Her concluding chapter, the kind of problem a city is, is still the most relevant. In it she attacks the scientific foundations of urban planning at a paradigmatic level, and claims that the methodology of the life sciences, at the time undergoing the revolution created by the discovery of DNA, is the correct approach to studying cities.

Death and Life of Great American Cities has been adopted by contemporary urban planners as a textbook for urbanity. Its descriptions of the characteristics of a city are now the models upon which new developments are planned. The old urban development of housing subdivisions and office parks is being substituted for the new urban development that has streets, blocks, and mixed uses, just as Jacobs had described to be characteristic of life in the city. A major difference between Jane Jacobs’ preferred city and the new urban plans remains. The layout of mixed uses is organized and planned in the same process as Le Corbusier planned his city designs. The scientific suggestions of Jacobs have been ignored.

The discovery of emergence and complexity science

In the time since Jacobs published her attack on planning science molecular biology has made great technological achievements and provided countless insights into the morphology of life. In parallel the computer revolution has transformed the technology of every human activity, including that of design. But the computer revolution brought along some paradigm-altering discoveries along with its powerful technology. In geometry, the sudden abundance of computing power made it possible for Benoit Mandelbrot to investigate recursive functions and his discovery, fractal geometry, generated a universe of patterns that occurred in many aspects of the physical universe as well as living organisms. (Mandelbrot, 1986)

Some thinkers saw that the life sciences were part of a much more general scientific domain. They formed the Santa Fe Institute and under the label complexity studied not only organisms but also groups of organisms, weather systems, abstract computational systems and social systems. This research formed a body of theory called complexity science that has resulted in the creation of similar research institutes in many other places, including some centers dedicated specifically to urban complexity.

Their scientific revolution culminated in two major treatises within the last decade, both from physicists practicing in a field of complexity. The first was A New Kind of Science by computer scientist and mathematician Stephen Wolfram (Wolfram, 2002), where he presents an alternative scientific method necessary to explore the type of processes that traditional science has failed to explain, presenting a theory of the universe as a computational rule system instead of a mathematical system. The second was The Nature of Order (Alexander, 2004) by architect Christopher Alexander, where he presents a theory of morphogenesis for both natural physical phenomena and human productions.

A definition of emergence

To define what is meant by emergence we will use the abstract computational system upon which Wolfram bases his theories, the cellular automaton. Each cell in a row is an actor, making a decision on its next action based on its state and the states of its direct neighbors (its context). All cells share the same rule set to determine how to do this, that is to say all cells will act the same way with the same context. In this way each row is the product of the actions of the cells in a previous row, forming a feedback loop. The patterns of these rows are not in themselves interesting, but when collected in a sequence and displayed as a two-dimensional matrix, they develop complex structures in this dimension.

The 30th rule of all possible rules of one-dimensional cellular automata produces a chaotic fractal when displayed as a two-dimensional matrix, but most other rules do not create complex two-dimensional structures. The first line of the matrix is a single cell that multiplies into three cells in the second line in accordance with the transformation rules pictured below the matrix. This process is reiterated for the change from the second to the third line, and so on. All the information necessary to create structures of this complexity is contained within the rules and the matrix-generating process. (Wolfram, 2002)

The same general principle underlies all other emergent processes. In a biological organism a single cell multiplies into exponentially greater number of cells that share the same DNA rules. These cells create structures in a higher dimension, tissues and organs, which form the entire organism. In the insect world complex nests such as termite colonies emerge from the instinctual behavior of individual termites. And in urbanization, buildings form into shopping streets, industrial quarters and residential neighborhoods, themselves overlapping into a single whole system, the city.

References

Alexander, Christopher (2004). ‘The Process of Creating Life’, The Nature of Order Vol. 2, Center for Environmental Structure
Corbusier, Le (1964). La Ville Radieuse. Éléments d’une doctrine d’urbanisme pour l’équipement de la civilisation machiniste, Édition Vincent Fréal et Cie, Paris, France
Hakim, Besim (2001). ‘Julian of Ascalon’s Treatise of Construction and Design Rules from Sixth-Century Palestine,’ Journal of the Society of Architectural Historian, vol. 60 no. 1
Hayek, Friedrich A. (1973). ‘Rules and Order’, Law, Legislation and Liberty Vol. 1, Routledge and Kegan Paul, London and Henley, UK
Jacobs, J. (1961). The Death and Life of Great American Cities, Random House and Vintage Books, New York, USA
Mandelbrot, Benoit (1986). The Fractal Geometry of Nature, W.H. Freeman, New York, USA
Wolfram, Stephen (2002). A New Kind of Science, Wolfram Media, USA

Squaring the circle

Natural paths of movement emerge through gaps in the blocks imposed by a municipal grid in the town of Tultepec, Mexico. These paths show how the street configuration of medieval cities comes to be defined. The urbanized gradient between the center of town and its outskirts shows the different stages in the emergence of a fully natural town.

For those with strong stomachs, scroll to the south to see some truly horrific modern housing blocks.

The complex grid

In a medieval-era city the pace of urban growth is slow to a point where the growth of the city is not consciously noticed. Buildings are added sporadically, in random shape and order, as the extremely scarce economic situation makes no other pattern possible. Typically this means that the shape of streets will match the existing natural paths of movement, giving the street network an organic structure that is preserved through successive transformations in the urban fabric.

This works until the street network becomes large enough to become a functional problem. Because it is random, the medieval street network becomes complicated to move around in once the structure exceeds a certain scale. Some people see this as an obstacle to commerce and project to restructure the emergent medieval grid into something more rational. These projects fail for the same economic reasons that shaped the emergence of the medieval streets.

As the pace of urban growth increases and as the cartesian paradigm expands in the 17th and 18th centuries, deliberate city planning through the pre-emptive definition of an urban grid becomes fashionable. The practice of baroque planning remains the privilege of ultra-rich landlords considering the scale of construction involved. (Louis XIV’s Versailles is still the case study.) In the Americas such concentrations of capital do not yet exist. Grids are not truly part of a city plan, they are the outcome of regulations meant to avoid the pitfalls of medieval urban growth. Although the idea of a block is defined, the limiting shape of the grid itself is undefined. This allows cities to grow out, in theory, infinitely.

This works until the grid encounters and existing structure in the landscape. While Europe’s land is already very complex, in America the land is mostly empty. One exception is New York, which has multiple grids expanding towards the center of Manhattan, all with their own alignment with the waterfront. Compounding the medieval streets below Wall Street, the city’s network is getting messy. The solution conceived is the first city plan of New York, the Commissioners’ Plan of 1811, which grids Manhattan in the pattern it is famous for to this day with the help of a concentrated political power. In Europe this much centralization is not available, cities being ringed by a large number of villages that already structure the land. One notable exception is Barcelona, which under conservative military domination had reserved a large non aedificandi zone outside of its defensive walls. With the military out of the picture, and the industrial revolution putting enormous pressure on the city’s growth, the next most famous cartesian grid plan is imposed: the eixample. Adepts of the medieval city such as Camillo Sitte praise its artistic value and quality of life, but fail to truly describe how to reproduce it in the context of accelerating urbanization.

The 19th century is the triumph of the cartesian plan. It is not only employed to plan cities but to plan the entire American landscape. West of the original colonies the map becomes rectilinear. The flexibility and fluidity of New York’s grid plan promotes very rapid land development and the city achieves growth rates never before seen. European city planners are facing the same growth pressure but are trapped by the land’s existing structure, both physical and political. One simple solution is discovered: demolishing city walls and building a high capacity road that encircles the city, the boulevard. If it is to be complicated to get inside a city, it will at least be simple to get around it. Paris builds two on its two successive walls, and Vienna builds the famous Ringstrasse. An interesting phenomenon emerges from subsequent growth. While the boulevards were meant to be restful promenades, they emerge to become important centers on their own due to their attractiveness for traffic. In space syntax terms, they are integrators.

Manhattan’s grid extends to over a hundred streets but starts to suffer from severe scale problems. The medieval street system drives traffic away to boulevards, but in an endless grid traffic goes everywhere, and there is no place that is free of the increasing congestion. With the introduction of the car the endless grid is in crisis. Since no better idea is found, the grid system is replaced with the high-capacity collector road to concentrate all the congestion, from which huge, isolated developments  access each other. This is the suburban sprawl system that remains the norm. It has the advantages of being simple to plan and giving enormous clout to land developers. However people are dissatisfied with the enormous scale of their environment. That they enjoy a single-family home does not sufficiently conceal the fact that they are clustered with thousands of similar homes, and next to those are huge strip malls, office parks and shopping malls that require long vehicle trips to access. The disconnect between their homes and their activities means they live in a form of crowded isolation. The suburbanites escaped congestion only to arrive at emptiness. There is more life in the less populated countryside. Adepts of the metropolitan grid such as Rem Koolhaas praise the culture of congestion as a lifestyle that the collector road fails to create.

This was as briefly stated as I could the modern history of the urban network: one system failing to adapt to the scale of the city, being replaced by a larger system that erases the small scale complexity of the previous only to itself fail at a much larger scale, and then another larger system crushing all complexity to resolve a problem of modernity.

Is there a way that we could have the benefits of all systems balanced as a whole urban network? To describe such a system, we can first define some proscriptions.

• Any size of urban growth is allowed as long as the new growth extends the boundary of the network. This ensures that the city has the economic flexibility of the medieval city and allows anyone, no matter their economic importance, to contribute to the city’s growth.
• The network must not become so complicated that it becomes impossible to move around in order to participate in large-scale activities and a culture of congestion.
• Streets must not grow too long without interruption in such a way that speeding and traffic accidents are encouraged.

How does this work out in terms of prescriptions? It turns out to be very simple. If we assume that we start with a hamlet of a single block, or a regional road that is undeveloped, we need only two rules: one for private development and one for the community.

• For private development: you may build on any available part of the network so long as you replace the part you used up by extending the network around your new block.
• For community development: any time a part of the network becomes too complicated (for example it takes more than 4 steps to get out of a sector), extend the boundary of that part with a higher capacity road (a boulevard).

How do we tell if these two rules really do meet the proscriptions we defined? Since we’re talking about an emergent design, the only way to see how it works is to do an explicit simulation of the computations involved. For this I employed a Fibonacci sequence to stand for a random growth process. With each new block that the sequence generated, I placed it in the section of the network that minimized the private cost of extending the boundary. I also used square blocks to simplify the computations involved, and also to demonstrate how such a process would work in a structure of land that has been made square, for better of worse, through cartesian planning. The process would work just as well in a more fluid, rounder land structure such as exists in Europe and the American East.

Stage 1: The village

The village is a cluster of houses and small businesses, whose only real challenge is maintaining a facade with the outside by ensuring that every new block also fronts the countryside. This provides the village with a path that everyone can walk around on whenever they want to get some fresh air and open space.

Stage 2: The town

The town starts to support development at larger scales with bigger block sizes. The first boulevards are built around the original village, preserving its traditional atmosphere from the growing businesses on the new boulevards.

Stage 3: The city

Now a significant regional center, the city’s economic complexity is heralded by the construction of the ring road enclosing the town’s neighborhoods. Large developments such as a regional shopping mall, an airport and a TND line the ring road alongside other smaller blocks of more traditional housing and business that take advantage of the high centrality of the ring and its new culture of congestion, eventually forming whole neighborhoods of their own. The ring road also encloses available green spaces for recreation, making it a parkway in some segments.

Emergent properties of the process

The most interesting outcome is that the structure of the network makes a very nice chaotic fractal, showing the balance between scales in the city’s growth. It is simultaneously simple to grasp and complex, living geometry.

The spatial integration created by the boulevards and ring roads also promotes the creation of a hierarchy of different centers that are evenly distributed between neighborhoods. Tightly knit residential quarters provide security for children and the elderly, with neighborhood centers within walking distance and no threat of heavy traffic until the edge of the city, liberating citizens from automobile dependency.

Adopting a complex grid is going to benefit small towns and villages most, as their economy is typically not large enough to support the collector road system. It might even result in the emergence of new villages in rural regions that have experienced large-scale urbanization and thus make them more resilient to economic shocks.

For existing cities, history provides a precedent for increasing the grid’s complexity when the problem is scaling up the grid. The urban renovations of Haussmann in Paris or Robert Moses in New York showed how to compose a larger scale within an existing city. (In Moses’ case, how not to do so as well.) However there is no precedent for scaling down a network that is too big, which is what modern cities suffer from. I suspect that contrary to scaling up which requires a strong centralization of power, scaling down involves a decentralization and a multiplicity of new powers transforming neighborhoods, breaking up regional, municipal and even neighborhood authorities such as homeowners’ associations to create local economies.