Category Archives: Theory

Design, configuration and natural form

When did human creations stop being natural? We look at a tower block, a subdivision or a shopping mall parking lot and see the worst of industrial civilization translated into form. We tolerate them as necessary to achieve the material wealth of our civilization. Those human settlements that are still natural we grant special protections through UNESCO and historical preservation laws. We do not have a law that promotes the creation of new historic settlements because we are not quite sure how they are made.

I believe that our mistake is not in the things we make, that there is nothing unnatural about a shopping mall parking lot from a design point of view. What makes the shopping mall parking lots we build so unnatural are errors in configuration of the design elements. To understand this, one must understand the difference between design and configuration.

The form of a tree is an ideal example to illustrate the difference between the two concepts. Any particular species of tree will have a design that is essentially the same from one tree to the next. The design elements in the tree are all the named parts: trunk, branch, leaf, root, bark, and so on. These parts are organized into hierarchical relationships with the whole tree and with each other. We will always find the roots related with the trunk in the same way. This relationship is a design solution that achieves a specific result. However, the position of any of the parts is not fixed. In the DNA of the tree are rules that instruct cells to adapt themselves to the larger context the tree finds itself in. The different design solutions that result from this cellular action will therefore adopt a position that reflects the particulars of time and place, ensuring that the tree’s form is perfectly adapted to its environment. This is why it makes no sense to create a description of the forms of a leaf in order to make another leaf – that form is relevant only to this particular leaf, and another leaf, although it would have the same overall design of parts, will take a completely different configuration.

Adapted to chaos

A chaotic configuration of a standard design

If you’re having trouble seeing this, imagine the following scenario: we take the DNA of a tree and clone it 100 times. Then we lay out a grid 10 trees by 10 trees and watch them grow. What would happen would be that every tree would come out a different way, since the earth around them would be structured differently, the wind patterns would be different, the shade and the moisture would be different. The trees would each have the chaotic, random shape that we know trees to have, yet would all be perfectly symmetrical with one another without being identical. Each clone would adopt a unique configuration of the same design.

When we look at a traditional village, we find that the same house design is repeated time and time again, but configured in such a way that it is differently adapted than the other houses. The reiteration of an often very simple design is all that it takes to create a natural landscape, so long as each house is configured to adapt to its place, and the design elements of the house are themselves configured to adapt to these adaptations.

One design, many configurations

Even today this kind of natural adaptation takes place in modern settlements where planning regulation allows it, or fails at forbidding it.

Monaco

This is the skyline of Monaco, which by necessity of the small size of the city had to be built piecemeal but yet is still made with an entirely modern building stock. The piecemeal process allowed each building to be configured to its site and thus, despite the fact that the buildings’ design is very basic modern architecture, the whole landscape looks natural. It would be even more natural were the architectural elements also adapted.

favela_rocinha_rio

This the Rocinha favela of Rio de Janeiro. Here the building design is as bare as could be made, the houses being built by poor residents with little capital to invest. But the resulting configurations adapt perfectly to the shape of the hill and the other buildings, and the overall look of the place is that of a human jungle. (If you have the chance to see this summer’s The Incredible Hulk, the movie makes this point by fading from an overhead shot of Rocinha to that of a tropical jungle, subtlety be damned.) The buildings in Rocinha are just as natural as the trees.

How does that translate back into our shopping mall parking lot? It means that although the relationship between the parts, for example the lanes, the spaces and the paint that demarcates them, must be defined, the length of the spaces or the thickness of the demarcations do not have to be identical from one element to another. The chaos of nature requires that they be slightly different from one to the next, and that means that the people who make them must be able to make decisions while they are building. Simply copying an AutoCAD drawing is unnatural. The design must be translated into a language that instructs the builders to make configuration choices while constructing the defined forms. This kind of language is how builders have made traditional towns and how DNA makes organisms.

Separating design from configuration also allows us to make a second attempt at city planning. The plans of modernists all had fixed configurations, and their failure to adapt to their context meant the failure of urban planning. The conflict between design and configuration planning dates back even further, to the 19th century plans for Barcelona and Paris. In Barcelona, Cerda planned a grid of square blocks through which he ran grand diagonal avenues. Those were only two design elements in a very strict configuration that was made possible only by the enormous economic pressure to expand Barcelona. In Paris, Haussmann did not have the luxury of expanding the city with blocks, he had to upgrade a city of blocks that already existed with a new design element, the grand avenue. He deliberately left the configuration of his avenues open until they were completed, and placed them where he met the least resistance. Their effect on Paris is even today essential to life, and they could not have been realized unless their configuration was left adaptive.

What would a natural urban design look like? It must first be a definition of parts that must be related to each other in order to create urbanity. Describe the relationship between the avenue and the streets, the streets and the alleys, describe the relationship between the avenue and the pavement, the pedestrian crosswalks and the shade trees. Describe the relationships with the buildings without delimiting their size and shape. The city builders will then decide in what configuration these elements need to be to fit their context, and the resulting built form of the city plan will be perfectly natural as well as fully planned.

Classicism describes itself as the imitation of nature. Complexity, on the other hand, does not imitate. It is nature, applied to different problems. To create the urban design of our time requires not adopting a certain style or program, but ensuring that any style or program can be adapted to a particular context. It only requires us to use different tools than what we have become accustomed to.

Further reading:

Complex geometry and structured chaos, part I and part II.

The challenge of dense sprawl

When looking at such a picture we are at first inclined to make a parallel with the landscape of Los Angeles. It is a foggy urban plain with a cluster of towers popping out over the horizon. This is Dubai from a perspective that is rarely shown, that of the city in the foreground, and its suburban expansions in the background. The towers are the Dubai suburbs, lined up on what used to be the main highway out to Abu Dhabi, now the centre of New Dubai and the urban fringe of Dubai. A picture such as this is significant because the central core of Dubai is almost never seen in the pictures of the huge developments going up in its suburbs. That is unfortunate, since the reason that these suburban developments are economically possible at their size is because they are growths of the old Dubai. The parallel with Los Angeles is therefore incorrect. Los Angeles followed the standard American model of urban growth, developing a central business district on a simple grid where the original center of the city was founded, then later adopted suburban sprawl to continue its growth and grew a cluster of skyscrapers adapted to this sprawl where the center once was. The policy of sprawl is blamed for the impossible traffic congestion that cripples Los Angeles, but generally what is meant by sprawl are the low-density housing subdivisions, office zones and other standard typologies of suburbia. The solution that was called for was more density, even though some geographers pointed out that Los Angeles was already one of the densest cities in America. The result of this choice has been dense sprawl: worse traffic, worse crowding and seemingly no improvement in quality of life.

Clearly the challenge of sprawl has been improperly identified. I will show that sprawl is not about density but about distance between complements, and the extremely rapid urban growth of Dubai, from a small fishing town to an urban metropolis in two generations, makes this visibly explicit.

Perhaps the most fascinating fact about Dubai is how natural and complex the old city seems to be despite having an entirely modern building stock. Most cities associated with a natural or organic morphology are usually pre-modernist cities of old classical or vernacular buildings, or at least preserve some of them. There are no such buildings in Dubai, the city having started its growth period in the 1950’s. The only explanation for the natural form of the old Dubai is a natural process of growth.

The urban fabric of a city is a solution set, each building being a solution to a problem of a particular time and place. The city as a whole is a solution set for its population as a whole, and as times and people change new buildings are added to provide new solutions to these new problems. The reason that naturally grown cities have a chaotic morphology is the same reason why stock market movement is fractal; they are both adaptations to fluctuating circumstances, and they are both limited in size by the previous size of the system. That means that you cannot grow a city by a development that is bigger than the city’s current state of maladaptation to circumstances. Attempting to do so will result in economic failure. Many very small development operations done in succession will be much more adaptive than one large development operation planned at one moment, since each operation adapts to the circumstances created by the previous one.

Because cities grow by correcting maladaptations, the new buildings turn out to be complements of the existing buildings. It makes no sense to make a building that is identical to one that already exists, and in natural cities that will never appear. Each building will be fitted to the particular knowledge of time and place, as Hayek would say. This particular knowledge is itself produced by the presence of existing buildings and the way people use them.

This process is not simply an economic abstraction, it also has morphological consequences.

Jumeirah is a beachfront suburb directly to the south of old Dubai that has become the home of the Anglosphere expatriate community as well as synonymous with upper-class lifestyles. Because it is more recent growth of Dubai’s urban centre it has seen growth in operations of much larger sizes. You can tell that there are now “clusters” of identical buildings, nothing of the scale of a metropolitan subdivision yet, but the building individuality of central Dubai is no longer present. (Cluster housing development is also visible in, for example, the older parts of Las Vegas.) This is pre-subdivision scale, in that an operation creates multiple buildings without having a scale large enough to be “planned” and have status as a named development. For the purpose of the adaptation they bring, they are still only one event, only one adaptation subdivided into multiple buildings. And because they are much bigger than the previous development operations, they create more distance between themselves and the urban fabric they are adapting to. The scale of development is not big enough to be called sprawl yet, but the complexity of this neighborhood is not as advanced as that of the older city. While the buildings in Jumeirah are certainly complements of the whole city of Dubai, they are not complements of each other, which is true in the older city.

Left: Skyscrapers on Sheik Zayed Road, Burj Dubai site on lower left

Right: Palm Jumeirah, Dubai Marina megaprojects along with random subdivisions.

Here are Dubai’s world-famous megadevelopments, which have been made possible as adaptations to Dubai’s metropolitan scale. The development operations are enormous complements of the existing urban fabric, but the fact that they are all being built concurrently means that they cannot adapt and become complements to each other. With little surprise the traffic congestion on the Sheik Zayed Road that integrates them together has skyrocketed. The distance between complements has increased to the scale of the projects, and the only way to move from one to another is by driving down Sheik Zayed Road.

The skyscrapers going up are actually making sprawl worse the same way that a development of 100 houses extends sprawl. The idea that a skyscraper is a vertical city is a myth. Skyscrapers are identical floors of open space and rely on very large networks of complementary urban fabric to work properly. Skyscrapers can contribute to the complexity of a place like New York City because the urban fabric of Manhattan is very rich and can digest density and congestion gracefully, but in a city where urban fabric is undeveloped, as modernist plans for a Radiant City were, or has been de-developed, like the CBD of most American cities, skyscrapers throw congestion and traffic out to the whole city as badly as a housing subdivision.

The solution to sprawl is not increasing density, but increasing complementarity. That means breaking up existing housing subdivisions, office parks and shopping centers into smaller autonomous parts that can grow into buildings that are complements to houses, offices and shops as well as complements to the city as a whole. (This obviously implies abolishing zoning.) It means not trying to design everything that goes into one project, to let growth come to you and to accomodate it, to publicize the chaotic symmetry of old Dubai as a model of natural beauty instead of the iconic forms of the skyscraper cluster. The Dubai Palms and the Burj Dubai district may still grow into something natural and complex.

The emergent dimension, or why New Urbanism is not urbanism

There are two methods for producing fractal geometry. The first method, the decomposition, is the most easily understood. In a decomposition we apply an algorithm that breaks up the geometry of some starting point into several parts. We then re-apply this algorithm to the smaller parts created, obtain many more, even smaller parts, and continue this reiteration until we have reached the complexity limit at the smallest scale of object we can possibly make. This is how an architectural design proceeds because it reflects the way that building proceeds. A building has a hierarchy of dependencies that begins with the largest structure, the frame. The building is then built with smaller and smaller components until we reach the smallest, for example door handles and light fixtures.

The other method is the composition. In a composition we also apply an iterative algorithm, but instead of breaking down the initial geometry, we expand it. The fractal grows out instead of growing in. This is how urbanisation proceeds, by composing new streets and buildings onto an already existing web of streets and buildings, until we have reached the complexity limit of the largest city we can support.

If we look at this compositional fractal we see that the scale of the structure composed to the initial geometry increases exponentially. The largest structure comes last.

Many of the elementary cellular automatons discovered by Stephen Wolfram produce this fractal using only one dimension of instructions. Each cell, depending on its state (black or white) and the state of its left and right neighbors, applies the rule to determine its new state. A new line is written for every iteration of the algorithm on the previous line. The complexity of the structure only becomes visible when the time dimension is displayed. At their local scale, the cells are not able to “see” how their actions create the system, but their actions do in fact make something bigger than themselves. They are creating a structure by emergence, and this emergence is visible only in a dimension larger than their actions: the emergent dimension.

I believe that the distinction between building and urbanisation, that is to say the distinction between action by decomposition and composition, also defines the distinction between architecture and urbanism. Architecture intervenes on a rigid structure defined at the beginning of the process, the building, and so runs into very strict economic limits of the scale of this large structure. Urbanism has to deal with the problem of creating large structures out of all of the small scale urbanisations that are undertaken by large numbers of individuals, all seeking to build something to suit their own personal problems. It is in that sense the inverse of architecture. Urbanism takes place in the emergent dimension.

The field of urban design has gained a lot of popularity since efforts to plan whole cities were abandoned. The focus of the urbanists has shifted to the scales considered controllable: the development, greenfield, brownfield and other. The most successful of the urban designers are the New Urbanists. They have managed to produce their name-brand Traditional Neighborhood Developments in practically every city in North America. It starts off inevitably with one developer and centralized ownership of the land that will be urbanised. This land is then decomposed into streets and squares along the principles proclaimed by the New Urbanist charter, the negative of which is decomposed into lots that will be further decomposed into buildings. In terms of production processes, New Urbanist TNDs are no different than the regular, economically-unsustainable subdivisions. They belong in the realm of architecture, and what is worse, they provide no connection to the larger urban context within which they are being inserted, suburbia.

Here is the Mackenzie Towne TND at the limits of Calgary Alberta, in mid-decomposition.

And here we see the development within the larger context of southern Calgary.

What were to happen to the people who have moved into the first part of the development if the developer declared bankruptcy, as has been the case in many developments these recent times? The construction site would remain in perpetuity, and their town would be incomplete. That is the very opposite of what a city is supposed to do, to provide a complete system regardless of the chaotic course of events.

Will the people of Mackenzie Towne live a New Urbanist lifestyle? One look at the bigger scale of the City of Calgary is sufficient to say no. The development is not the relevant scale of the urban life of its inhabitants. This follows from the fact that it is only a small part of the city as a whole, but is also what makes urban design economically possible in the first place. In order to be able to undertake a decomposition at that scale, we must be composing it to a much bigger system of urban relations.

I fear that no matter how intense the efforts the New Urbanists undertake to convert local authorities to their system, they will never be able to transform cities in their emergent dimension. We will continue to see appear, alongside TNDs, gigantic commercial strips, industrial zones and office parks, which will continue to form the emergent dimension of North American cities. At their center will be the caracteristic integrator of all of these urbanisations, the one space that every inhabitant of any modern city shares, the highways.

What then is urbanism? It is the glue that sticks different urbanisations, different architectural projects, together. North America has known only two general types. For all of the 19th century, and the first part of the 20th, the urbanism of North America was The Grid: unending checkerboard patterns of streets between which were blocks that were more or less developable into anything not bigger than the block. As cities grew with more urbanisations, new streets and blocks were composed onto existing streets and blocks, and this went on until the urban chaos became intolerable and people fled to the suburbs, a flight that was enabled by the new urbanism: the highway strip. The highway strip continues to be the compositional rule that integrates all North American cities. If you look again at Mackenzie Towne, the highway that borders it seems to have no relation at all to the development. This amounts to no urbanism. The emergent dimension is empty of any structure.

The New Urbanists have launched a parralel effort, alongside the TND, to reform municipal authorities’ urbanism by inventing a building code, the SmartCode, that is supposed to fit into any city. Building codes have been the primary tool of urbanism for centuries. The reason they worked so well is that they made it possible for the smallest possible urbanisations to create large-scale structures, balancing local adaptation with large-scale solutions in order to create what we today call organic cities. Such a building code can do much to enable complexity, but it must be combined with the creation of the integrator spaces, streets, avenues and highways, that must also grow organically.

Looking over the fact that it doesn’t appear to provide any indication of what to do with highways, the SmartCode ran into the objection that it was rules, and therefore anti-market. Ironically, the market is one of the first rules-based complex systems fully investigated. Adam Smith even christened its emergent dimension with a metaphor that continues to mystify people today: the invisible hand. The invisibility of the market results in many hotly-debated political issues, for example the incomprehension with surging gas prices during hurricanes. The reasons why gas prices should rise so rapidly escape the individual perspective, and angry commuters everywhere demand from politicians that something be done to control things. That attempt at control of the market would have unexpected consequences, just as it does in the emergent dimension of urbanism. Brasilia was the most famous realisation of fully-controlled town planning ever built, but today it is ringed with favelas and functions as one city with them. The emergent dimension of Brasilia escaped the strict control of its planners.

Urbanists must, by the nature of their work, be experts at seeing things in the emergent dimension. The tools to achieve that have yet to be invented. Economic treatises crudely made the case for the economy as an emergent system, but the 200 years of economic history that followed them showed that people would not believe what they could not see. They will not believe in the SmartCode until they can see it either. The invention of the microscope made it possible to see what was too small to see. We must invent the tool that makes it possible to see what is too large to see. Only then can we truly begin to create the cities that we want, as individuals and as communities, without taking a blind leap of faith.

Reference

Sustainable algorithmic design lecture series by Nikos Salingaros.

Complex geometry and structured chaos part II

Complexity, to employ the definition proposed by Jane Jacobs in the final chapter of Death and Life of Great American Cities, is a juxtaposition of problems. This implies that a complex solution is a juxtaposition of solutions: fractal geometry.

How does the way we build arrive at complex solutions to complex problems without driving the builders to madness? How can we solve problems which exist at every scale in space, but also exist at every scale in time? Let’s take a look at St. Paul’s Cathedral in the City of London.

Let us focus on two different parts of it, the dome and the belltower. At first sight, there is nothing that a dome and belltower have in common. They are two different forms that solve two very different scales of problems. And if they had been built very far apart in two different neighborhoods of the city, one would never even associate them together. Yet in this case they are not only “dome” and “bell tower”, but they are also part of a greater form we call “St. Paul’s Cathedral”. That is to say, their form not only solves the problem of providing a dome and a bell tower, but it also contributes to solving the problem of providing a cathedral. Several scales of solutions are juxtaposed in the same space in order to form a complex solution. How was this result achieved?

Perhaps the architect Sir Robert Wren was a genius, but intuitively we doubt that, since the geometry in St. Paul’s cathedral is very similar to the baroque geometry employed throughout Europe at the time. And when we think back to how the Gothic cathedrals were built, very slowly, sometimes over more than a century, they were necessarily built by more than one architect. If they were all geniuses, then they must have been lucky to find so many geniuses idling about in medieval Europe. That sounds impossible given that medieval cathedrals appear to be even more complex than St. Paul’s cathedral, even though more people worked on their construction over a greater timespan. The sublime Antwerp cathedral, for example, was built from 1351 to 1521, and never completely finished.

There has to be a key to this riddle. How did we lose the skill to make this kind of complexity?

Since Leone Battista Alberti heralded modernity (not to be confused with modernism) in architecture, and until the mid-20th century, architects spent their first days in training learning to draw the classical orders. These classical orders supposedly held the finest refinement of western civilization’s building culture, having been in use since Greek antiquity and maybe earlier. It was an architect’s duty to reproduce this culture by learning the orders. Any deviation would certainly cause the doom of civilization. What the orders actually consisted of were fractal nesting rules, settled on more or less accidentally through the ages. Since the abstract concept of fractal nesting would not be discovered until Benoit Mandelbrot’s work in the 1970’s, the orders were simply understood to be unquestionable tradition. Since they were very simple local-form rules, any architect could use them to make his building, and they could be taught to any laborer working on any specific sub-section of a building without his having to know his role in the form of the whole. They could even be used to make simulations of the building, drawings and scale models that would later be used to convince patrons to fund construction. The rules were always the same. Only the problems to be solved changed.

Let’s take a look back at Wren’s cathedral. What does the dome consist of? Nested structures, including columns. What does the bell tower consist of? Nested structures, including the same kind of columns. The two different problems to be solved, dome and bell tower, also happen to share the same nested problems, and when they share a solution to this problem, they become connected into a whole.

Once we are aware of this rule we no longer need a necromancer to reanimate Wren in order to build an addition to the cathedral. We can simply decompile the geometric rules and apply them to solve the new problems we face. Whatever we produce that way will belong to the cathedral as much as the original parts. But we can also extend this to the scale of an entire city. If we apply these geometric rules to build a house or an office tower, it will appear to belong as much to St. Paul’s as the bell tower and the dome do. This enables us to achieve the complexity limit of urbanism. And when we look at all the great cities of the past, Paris, Rome, Venice, Amsterdam, Mediterranean hill towns, what we find is that they look whole because the builders who made them were all using the same rules in order to solve their individual problems. They didn’t realize they were doing it, they were just doing it because that’s how things were done.

If the classical orders were so great, why are they no longer being taught? Up to the 19th century, building technology changed very little, and so simply repeating the tradition was enough to create complexity. When metals and glass became massively affordable in the industrial revolution, architects faced a puzzle. Although the traditions succeeded at creating complex solutions, they were no longer solutions to problems that were relevant to anyone. Some architects experimented with new rules for nested structures using the new materials, more or less compatible with the old rules, and that gave us Art Nouveau and the Eiffel tower, for example. And some more radical architects, such as Louis Sullivan, said that modernity required the invention of a whole new architecture, and this became known as modernism. The modernists were right to declare the classical orders irrelevant, but in their rejection of the very foundations of architecture, the application of simple nesting rules, they also made it impossible for themselves to create complex buildings, and the result is the architectural wreck that unfolded starting in the 1930’s. The worse culprits, no doubt, were those modernists like Le Corbusier and even Albert Speer (bet you wouldn’t think he was a modernist) who favored abstraction and repetition in architecture. Abstraction is only the denial of complexity, the physical nature of our universe. It is the architectural equivalent of playing ostrich.

Post-modernism tried to bring back traditional forms without really giving up modernism, and that was a disaster perhaps worse than modernism was. Since post-modernists did not create nesting rules for their architecture, and on top of that were bringing up forms that were solutions even less relevant now than when they were abandoned, the result was a worldwide goofy architecture that everyone mocks as pastiche.

Some architects have been stumbling upon the right path these last few decades. The most remarkable effort has been the remodeling of the Reichstag in Berlin by Norman Foster.

The old building represented the federalist traditions of Germany, but also had to be adapted to the new philosophy of popular democracy. Foster built a glass dome from which the people can look at their politicians at work while enjoying a wonderful panoramic view of Berlin. Foster nested a new solution to a new a problem within the traditional geometry of the Reichstag, and thus created complexity that is relevant to the problems of today.

Architecture is, ultimately, just the repetitive computation of simple geometric rules to solve complex problems. Necessarily that creates complex solutions, and truly fractal buildings. With the right ruleset, anyone can do architecture, and by extension, great cities. The rules guide your hand.

The emergence of a sense of place

Modern urbanism has given us a landscape that many consider to be soulless. Everything looks the same. Nothing creates a sense of place. New Urbanism has attempted to reverse this by returning to traditional architecture and town planning forms. This was done in European new towns, under the advice of well-meaning men like the Krier brothers, in the late 1970’s, and did not succeed. While there are blocks and squares and on-street parking, the general configuration of traditional towns, the new towns did not develop the identity and personal relationships with their inhabitants that was intended with the return to traditional forms. They still experience the same population mobility that the other suburbs of the periphery experience.

The reason this happened is the same reason that New Urbanism has not caught on, despite the fact that everyone agrees with it. The New Urbanists have been focusing on outcome instead of process.

Complexity is an emergent phenomenon. This means that its outcome cannot be determined, that only the process of emergence can be determined, and the outcome must be what results from this process unexpectedly. The sense of place that we seek is not traditional town plans, although those have merits of their own, but the realization of our personalities in buildings.

Home renovation has become the cultural expression of the landed middle classes, and the propagation of the home renovation big box chains is a testament to this culture. I cannot have a single conversation with any middle aged home-owning couple without some renovation project of theirs being mentioned, and I shudder to think how conversations go when they are amongst themselves. I believe that, more than a form of consumer culture or cocooning, this trend is a reaction against the placelessness of suburban environments. As the standardized, tract homes are transformed at small scales by their residents, they come to reflect the choices and personalities of the individuals that inhabit them. This is what had been missing from the speculative, mass-produced housing that colonized the periphery and eventually exploded across the entire landscape. Once buildings have been transformed by someone, the presence of this person is felt in the building’s form. It becomes a unique historical event, and thus forms a place.

How does repetition of identical buildings come to be? The answers are in the building processes. Repetition was never seen prior to the industrial age, and even through the industrial age not all cities actually saw mass-produced housing. American cities laid out on grid patterns all have their share of row buildings, as does London. But in London the trend started with terrace housing for the aristocracy, and other centers of industrial revolution in Europe, such as Paris and Berlin, have no trace of repetition at the scale of working-class neighborhoods in industrial America. The simple fact of industrialization cannot explain this kind of urban morphology. Even today, while the construction of repetitive housing subdivisions continues in the post-industrial world, the industrializing countries such as China are constructing wildly individualized buildings inside the existing urban fabric. And in the informally economic shantycities of Africa and favelas of America, personalized building is the only rule. The latter feel more alive, although less comfortable. That living quality, the result of millions of individual acts of transformation to create fitness, is what gives a place its placeness. But in order for this quality to emerge, there must be a personally-enabling urban process at work.

Christopher Alexander theorized such processes in his Oregon Experiment, where he also wrote a scathing criticism of city plans. He described how the directors of urbanism for the University of Oregon could act to enable the creativity of the inhabitants of the university in the elaboration of new buildings that would solve their personal, individualized problems. This would be the opposite of designing a plan for the university’s expansion that would then be imposed on the inhabitants in perpetuity

The traditionalist New Towns I mentioned do have such plans, and they do forbid personal transformation on the urban fabric. This is why they remain only a product and have not grown into a place. The same fate awaits suburban subdivisions where strict HOA rules forbid changes.

Beyond those two cases, a larger problem still has to be challenged. Why is it that the processes of urbanization in our countries limit or destroy complexity, while enabling it in foreign countries? We must take a critical look at our processes, which are unfortunately often enshrined by government legislation, and replace them with those processes that enable the emergence of complexity. Only then can a new urbanism be achieved.

Placeless:

Regular, oppresive tract homes.

Placefull:

Reference

Alexander, Christopher and others. The Oregon Experiment.

Fitness is about symmetry

On City Comforts they make the case that Daniel Libeskind’s abominable extension to the Victoria and Albert museum could be made to fit with the museum and South Kensington in general. To support this they link to this Good City post on traditional neighborhoods and modern architecture, which argues that the only thing necessary for a modern building to fit in a traditional neighborhood is that the site plan be well integrated into the public space. As evidence for this they show a picture of a modern house in Lincoln Park, Illinois. The house in that picture actually has qualities that the Libeskind addition doesn’t have, mainly that it has several scales of geometry symmetrical with its context. The walls of the modern building are symmetrical with the walls of the historic buildings, and all buildings are thus linked together into one fabric. The windows are different, but that is the outcome of adaptation to changing needs, which requires new scales of geometry.

Integrated site plans are a necessary but insufficient condition of good urbanism. The idea that you can make a whole out of an anything goes architectural approach was rejected even by nihilist-leaning Rem Koolhaas. In complex systems symmetry is found because it is the most physically efficient process. Remembering that the definition of symmetry is a preserved structure after undergoing a transformation, we can more clearly define what kind of modern architecture is good for a historic neighborhood. A new building fits into a historic neighborhood if its geometry can be derived from an old building with the fewest possible transformations. That is to say, all reusable scales are reused, and the modern building has all the useful new geometry that we require in our time. What makes a neighborhood historic are those reusable scales and not the age of the buildings. The building in Lincoln Park reuses the wall scales of its neighborhood. Now try picturing it with bright rainbow walls and neon. Does it fit anymore? No more than does the Libeskind extension.

Rue d\'Aubervilliers, Paris 19

Here is a similar building in Paris’ 19th borough. Its site plan is as urban as could be made, but it is definitely not Parisian. It has no scales in common with its neighborhood. This happened despite the fact that the majority of real estate in Paris is modern. Modern Paris goes unnoticed because it is symmetric enough with its neighborhood that it contributes, or at least doesn’t take away from, the city as a whole.

Scale-free urban systems

In previous comments, I have argued that what makes cities different than building projects was the fact that they have to deal with change and uncertainty, and that subdivision-planned developments are economically inferior to random growth. These arguments rely on the fundamental quality of cities as systems, a property that places them in the same class as biological systems while separating them from mechanical systems. This quality is being scale-free. That is to say, a city can work no matter what size it takes.

The ability of a system to function at multiple scales is behind the growth process of all multicellular lifeforms. It all starts as a single embryo, multiplying into thousands and millions and billions of cells. These cells work together to emerge the form of a sapling, which immediately begins to function autonomously as it grows into a full-sized tree. The processes in the DNA of a tree are able to function at whatever scale the tree grows. They can work even if half the branches are cut off, for example to make one of those distinctively-French square trees.

It should be obvious that this is a radically different quality than those possessed by mechanical system. We cannot imagine a car growing with us over the years. We cannot imagine a car working if one of the wheels is taken away. In a mechanical system, action is linear. If one system or sub-system fails, the whole structure fails. In a scale-free system, no single sub-system is that critical, although they each have a marginal impact on the total efficiency of the structure. So a tree might not die from being cut square, but it will not function as efficiently.

The idea of creating something whose size is not going to be known is alien to engineering and architectural practices. But this is not to say that it has never been done before. The Internet is without a doubt a great achievement of scale-free system design. Its foundations, Arpanet, was intended by the military men to be a communications system that could function through a nuclear war, which implied a catastrophic loss of infrastructure in random places. The cables and links that you are using relate directly back to this original system, and they have grown to such a scale that no one really knows how big it is. If it works, don’t fix it. But how does it work?

The idea of a network that could continue to function despite bombardment was actually demonstrated in World War II, when large-scale strategic bombings of cities devastated Germany and Japan. Quite surprising was the fact that, instead of resulting in a massive exodus of urban populations to the countryside, leaving ghost towns behind, bombed cities continued to function, supporting the lives of their residents and industrial war effort, although with greater hardship. Despite catastrophic reduction in scale, cities adapted and continued to work. The modernist plans for cities of 1,000,000 people of the time were set up to fail. By designing in advance the final form of a city as if it were a building project, just bigger, modernists failed to understand the fundamental benefits of cities. Even those plans that were realized, like Brasilia, face intense pressure to change their scale and grow new relationships, as witnessed by Mr. Bill Hillier.

The systems that allow the internet to work are founded upon relational rules. It is by defining protocols for how different networks relate to one another that all of them come together to form the Internet, without any of them being really aware of the scope of the entire system. The form the system takes is fractal. (A fractal is a relational rule applied repeatedly.)

The most simple form a city can take is that of a village on a road. But what is the difference between one village in the countryside, and 100,000 villages in a metropolis? It is the spaces that tie them together at a larger scale. From an “urban village” where your house is you enter an avenue, which has shops and activities and businesses along with faster movement. The avenue relates the villages together, and the grand avenues relate the avenues together. The expressways link the grand avenues, all the way up to the airports who link the cities together. Building these relationships is the basic day-to-day work of city corporations.

Relational rules also appear in the essential tool of urban planning, the building code. Building codes ideally allow the maximum flexibility in local problem-solving, the design of a building, while integrating the building smartly into the urban fabric of the city as a whole. A good building code is itself scale-free. It defines how anything from a bungalow to a soaring skyscraper is to be shaped in order to be compatible with the whole.

If done right, a city plan will work beautifully whether it is growing or shrinking, whether it has ten inhabitants or ten million. The job of designing cities is not so much about determining form, but about defining the processes that will generate their form.

The movement economies

Bill Hillier of Space Syntax is, along with Christopher Alexander and Michael Batty, part of the British old school of urban complexity researchers. (Hillier has joked that he would have used the term “Pattern Language” instead of Space Syntax had Alexander not used it first.) He has studied the functional impact of spatial relationships on human behavior over a career spanning several decades, and came upon some very insightful results. The synthesis of his career was published last year in the book Space is the Machine, which you can read here.

Hillier presents a theory of urban emergence founded upon two ideas. First, that circulation in a city is determined by the configuration of lines into a global hierarchy of depth, which he calls integration. Second, that activities in the city adapt to take maximum advantage of this movement, a phenomenon he calls a “movement economy.”

How did he draw this conclusion? By observing that integration of lines could predict where all the major shopping streets in London are.

Which then is primary? Let us argue this through the spatial distribution of retail, the commonest non-residential land use. We may already have been suspected of having confused the effects of spatial configuration on movement with the effect of shops. Are not the shops the main attractors of movement? And do they not lie on the main integrators? This is of course true. But it does not undermine what is being said about the structure of the grid as the prime determinant of movement. On the contrary it makes the argument far more powerful. Both the shops and the people are found on main integrators, but the question is: why are the shops there? The presence of shops can attract people but they cannot change the integration value of a line, since this is purely a spatial measure of the position of the line in the grid. It can only be that the shops were selectively located on integrating lines, and this must be because they are the lines which naturally carry the most movement. So, far from explaining away the relation between grid structure and movement by pointing to the shops, we have explained the location
of the shops by pointing to the relation between grid and movement.
(SITM 125)

Once it has been demonstrated that it is the global network structure that determines where most of the movement will go, not any particular destination, then what remains to do is to exploit this movement. This is the movement economy. It is, in one sense or another, behind every act of urbanism, operating at every scale.

Every trip in an urban system has three elements: an origin, a destination, and the series of spaces that are passed through on the way from one to the other. We can think of passage through these spaces as the by-product of going from a to b. We already know that this byproduct, when taken at the aggregate level, is determined by the structure of the grid, even if the location of all the a’s and b’s is not.

Location in the grid therefore has a crucial effect. It either increases or diminishes the degree to which movement by-product is available as potential contact. As we saw in the coloured-up maps, this applies not only to individual lines, but to the groups of lines that make up local areas. Thus there will be more integrating and less integrating areas, depending on how the internal structure of the area is married into the larger-scale structure of the grid, and this will mean also areas with more by-product and areas with less.

Now if cities are, as they were always said to be, ‘mechanisms for generating contact’, then this means that some locations have more potential than others because they have more by-product and this will depend on the structure of the grid and how they relate to it. Such locations will therefore tend to have higher densities of development to take advantage of this, and higher densities will in turn have a multiplier effect. This will in turn attract new buildings and uses, to take advantage of the multiplier effect. It is this positive feedback loop built on a foundation of the relation between the grid structure and movement this gives rise to the urban buzz, which we prefer to be romantic or mystical about, but which arises from the co-incidence in certain locations of large numbers of different activities involving people going about their business in different ways. (SITM 126)

From this knowledge, we can arrive at a paradigmatic definition of urbanity. A space can be considered urban if it makes maximum economy of the movement that passes through it. A city, at any scale, will be qualified as a good city if the experience of movement is not felt as a burden but as an opportunity and pleasure.

A visitor from Canada once remarked to me that he had walked from the Eiffel tower to the Pantheon, a trip of more than 4 kilometers, without feeling the distance. This is something he could never have done back home, where inevitably one would run into long stretches of mind-numbing repetition or parking lots. Paris, on the other hand, offered him a path through the city that was rewarding his presence. Certainly the excellent late 19th-century residential architecture plays a role in creating a basic comfort level, but architecture alone does not distract for such a long distance.

Paris is known as a city of highly sophisticated urbanity, and this is attributable to the efficient movement economy that was seeded there during the Haussmannian period. The most integrated lines, the typical boulevards and avenues, have been constructed in such a way that they make maximum use of residual movement. And what may be most surprising, a revelation that the occasional tourist will miss out on, is that the least integrated lines, the common residential streets, are generally quite boring, bordering on unpleasant. They are rarely seen by anyone except their residents due to their spatial segregation. It is safe to say, then, that the “real” Paris, what makes the city worth visiting, are its highly integrated spaces.

How do these spaces realize movement economies? Firstly they provide multiple scales of movement as well as the interfaces between those scales of movement. The grand avenues centered on the Arc de Triomphe are in fact three different scales of movement: promenade, street and highway, connecting into each other. While someone crossing the city in an automobile would be exposed to all the activity taking place on the promenades, he could decide to pull over into the street section, curb-separated from the highway section, and park his car in an available spot, then walk to his chosen destination. While walking there, he encounters shops he could stop in if it occurred to him to make a purchase. Restaurants and fast-food outlets provide him with a convenient option for dining. On the street side, news kiosks offer him information and headlines. All of this benefits him and occupies his mind at no cost as he was already taking this path for other reasons.

While he is walking to his destination, people are sitting in sidewalk terraces drinking beer and coffee, watching him walk by. They are also taking advantage of movement. William H. Whyte, author of the classic The Social Life of Small Urban Spaces, observed that the primary activity that takes place in plazas is people-watching, people moving through that is. On the Avenue des Champs-Élysées, the most trafficked in the city, restaurants have outdoor dining rooms right between the highway and the pedestrian flow. They are highly prized, despite the noise and wind, because people enjoy watching the movement.

Since Alphand, the city of Paris has split promenades into three strips. The center strip is the open space through which pedestrians walk. The street-side strip is for street furniture such as kiosks, public washrooms, benches, bus stops, and so on. The building-side strip is for “concessionaires”, retailers and restaurants renting a part of the street to open their space to the exterior. The formula for a good promenade is that simple.

Needless to say, it takes quite a lot of movement to support so many mutually-dependent activities. But high-end avenues are not the only spaces that can take advantage of movement economies. Urban movement is fractal (it occurs at all scales). Hillier found that placing a limit on the range of movement, one obtained a local integration map that was different than the global integration map, and the movement in this locally integrated space was qualitatively different than global movement. These locally integrated paths develop local movement economies of their own. Typically, while highly integrated paths will become high-end shopping streets, locally integrated paths will be neighborhood service streets. Instead of trendy restaurants, fashion boutiques and cinemas, you find supermarkets, bakeries, post offices and cafes. And when we look at things with enough abstraction, we can see that even a shopping mall is a form of locally-integrated movement economy, where anchors terminate important axis and boutiques support each other by intercepting movement. Kiosks and cafes now take up even more space in the center of shopping mall promenades than they do in Parisian boulevards. It should be no surprise that people who live in suburban cities reflexively head to the mall for activity. Shopping malls, in the suburbs, have the most densely developed movement economies!

Besides creating commercial potential, movement economies also provide security. This is something that Jane Jacobs insisted on in Death and Life of Great American Cities through her concept of eyes on the street, but Hillier found an inverse statistical correlation between burglaries and spatial integration. What this brings us to is that there is a lower bound to urbanity, that we have defined as the realization of movement economies, where spaces lose integration and become segregated. If there is not enough movement, there is no purpose to public space. This is the point where public space becomes pathological, and where “defensible space” becomes necessary. Disastrous social housing projects have become the textbook case for failed public space, and their segregation explains their pathologies.

Parisian urbanism offers another excellent solution out of this problem. While the avenues are congested and noisy, full of life and activity, the lots are organized as courtyards from which several buildings are accessible. These courtyards are locked behind digitally-secured coach doors. It is rarely the case that one is invited to a dinner party without being given several “digicodes” to get through the secured, segregated spaces. Once in the courtyard, the noisy street becomes peaceful silence. These courtyards are functionally identical to the despised suburban cul-de-sac. But the cul-de-sac is not the problem, the streets they connect to are the problem. Paris balances two extremes, highly public, highly integrated space and completely private, gated space, side-by-side, supporting each other. Manhattan’s street-and-skyscraper urbanism is essentially the same, except that instead of going deep away from the street, one has to go up after entering segregated space.

New Urbanists in America and compact city advocates in Europe insist on having fully open grids, sometimes with alleys, instead of cul-de-sacs. There is nothing wrong with a cul-de-sac in itself; it is only a large residential building turned on its side. The important work is creating density in highly integrated lines. Arturo Soria y Mata invented the linear city in the 19th century as a utopia, but in reality, all cities are linear cities, functioning at fractal scales. The realization that the spatial integrity of the line is more important than anything that goes on behind the buildings occurred to me while taking a bus through the west Paris city of Nanterre, widely acknowledged to be a wasteland. The line the bus was taking was well composed, and I did not realize where I was until I caught a glimpse of wasteland Nanterre in a gap between two buildings. So far as anyone on that street was concerned, this didn’t affect them negatively. That is how resilient urban fabric can be.

Afterword

Local integration map of Central London

From Space is the Machine, global and local integration maps of Central London.

Self-organization of cities around natural movement is an important demonstration of complexity. Without anyone having willed or designed it that way, the aggregate actions of the millions of residents of London, all randomly travelling from one point to another of the network, resulted in the production of a fractal structure of the urban grid.

References

Bill Hillier. Space is the Machine
New Science. New Urbanism. New Architecture – Proceedings from a London conference, Katarxis.

A demonstration of complexity in London

The immensely productive Physicist-Mathematician-Entrepreneur Stephen Wolfram theorized, based on his studies of cellular automatons in the 1980’s, that there exists four classes of physical processes in the universe. Class I is simple continuous behavior (line). Class II is repetitive behavior (checkerboard). Class III is nested, hierarchical-fractal behavior (basic fractals like the Sierpinski triangle). Class IV, the most fascinating, is chaotic behavior (random fractals such as the Mandelbrot Set). Wolfram believes that Class IV behavior, exemplified by the Rule 30 automaton, is behind the complexity we see in the universe, and that very simple generative rules produce it.

The way we as humans are used to doing engineering and to building things, we tend to operate under the constraint that we have to foresee what the things we’re building are going to do. And that means that we’ve ended up being forced to use only a very special set of programs–from a very special corner of the computational universe–that happen always to have simple foreseeable behavior. But the point is that nature is presumably under no such constraint. So that means that there’s nothing wrong with it using something like rule 30–and that way inevitably producing all sorts of complexity.

Wolfram gave this speech on his new science to big shot architecture schools at Yale, Princeton and MIT. He believes that his new science has profound implications for the generation of form in architecture. I agree with him, but not for the reasons he provided. In fact his classification of the geometric properties of different physical phenomenons provides extremely profound insight into the history of architecture, and its future.

A visit to London was what really made me appreciate this insight. London, as an architectural artifact, is quite unique in that its greatest period of growth, the period 1750-1850, coincides with the beginning of modernism in architecture, a time when architecture became in a sense aware of itself and in search of its meaning. Neoclassicism was followed by Gothic Revival, Romanesque Revival, Neo-Venetian, all of it got mixed up in eclecticism, and the invention of new materials and building processes came to confuse things even more. Regardless of stylistic debates, what may be most important about that period is that, for the first time in history, large capital funds for speculative real estate development became available. Where architecture had once been a piecemeal business occurring quite randomly, in London, for the first time ever, housing subdivisions were possible. The result was the terrace housing.

Chelsea South Kensington

The big housing developments in London were initiated by aristocratic landowners who hired architects to plan and control the form their estates would take. Walking through Chelsea and South Kensington, one is faced with sometimes overwhelming repetition of identical houses. Class II behavior, that Wolfram claims is fundamental to engineering, is obviously visible. The architects of the estates, not really knowing the specific constraints of the future residents of the place, opted for endless repetitions of the same building. The fact that each building is a copy of the next, inadapted to the particular wants of its occupants, makes it standard behavior, far from complex.

The human mind is by nature fractal and is repulsed by Class II geometry, which is why traditionally architects have built Class III, hierarchical fractal geometry. This was employed by some terrace builders, such as the architect of the Regent’s Park estate, John Nash. Here the monotony of the model is interrupted by nesting houses in flourishes like arches, or bigger houses with large porticoes.

Cumberland Terrace, Regent’s Park, London

You can see a 19th century panorama of this terrace here.

Classical architectural education, based on the teaching of the classical orders, trained architects in the art of doing such hierarchical decompositions of their buildings. As such most of the high western classical architecture, starting from the renaissance architecture of Alberti (the first modern architect in the sense that his name is more important than any of his buildings, not true of the medieval architects of cathedrals), is rigidly symmetrical. Classically-trained architects only expanded the scales of decomposition as the size of buildings increased, up to the neoclassical skyscrapers that modernists considered to be ridiculous. The classicals were right about the need to create fractal geometry by decomposition of what were rigid engineering plans, what the modernists claimed was ornamental crime, philosophically dishonest and replaced with elementary repetition in their designs (regression to type II geometry). People have hated architects ever since.

Whenever I read through architectural history books, even those of honest traditionalists like David Watkin, I am struck by what is clearly missing from the record. That is to say the towns built up over centuries, the accretion of simple building acts into complex symmetries. The topic is touched by some thinkers of urban morphology, typically under the label of “organic” growth, such as in The City Shaped by Spiro Kostof, but everyone appears dumbfounded by the means through which such symmetry was accomplished. And largely the whole career of Christopher Alexander has been dedicated to decoding this mystery.

Andalusia

But even in the 19th century, when large-scale development was sweeping London, some complex geometry was achieved. These are four distinct buildings on Lincoln’s Inn Fields.

Lincoln’s Inn Fields

We immediately notice that each building is different from the other, having been built for a unique purpose and therefore being a unique solution to a unique problem. Despite that, the buildings form a harmonious geometric composition because they share many transformations to which randomness is applied. Even within one building, Lincoln’s Inn on the left, randomness is visible. The tower is unique, but symmetric with the rest through shared transformations. What we are seeing here is, I believe, a genuine Class IV pattern.

How could this be possible? If Wolfram’s theory on the origins of complexity is correct, then there must be a very simple rule to produce this kind of street scape. This rule can be applied to any random architectural demand and provide a perfectly appropriate solution to an individual problem while remaining completely harmonious with other such random solutions in its neighborhood! Since such organic complexity appears in all human civilizations, then we must conclude that every single building culture in the world has known, at some point, such a rule, and has applied it to solve building problems of all forms. Without understanding how these rules created complexity, they simply repeated them after each successful building.

What to do with new technology? New technology necessarily creates a new scale into the rule, but the remaining rules are still valid. This is visible in the glass structure appended to the Royal Opera House.

Royal Opera House

We can see many shared patterns between the central structure and rightward structure, but not with the new addition on the left. Typical of modernist architecture, the left building is only made of elementary geometry, barely even qualifying it as a Class II structure. It doesn’t feel as though it belongs there at all. There is an important lesson here, one that architects I fear do not want to learn.

Wolfram claims that complexity science is about finding simple rules that can generate complexity. We can decode simple rules from traditional architecture that, even with the modest means of poor villagers, will generate complexity when applied repeatedly to random events, creating random fractals while simultaneously solving a vast diversity of unique problems. This is exactly the kind of work that good urbanists should be doing today, and from there we could allow maximum diversity in our cities without breaking symmetry and harmony at costs as low as the meanest buildings currently cost. If Wolfram is correct, then the rules may be so simple that they may be easily codified into building regulation even by the dullest bureaucrats. Then again the behavior may be so complex (that is to say there is emergence) that no a posteriori codification is even impossible, and the processes by which cities are governed may have to be completely reconsidered. Either way this is not good news for architects. If architecture is so easy, then their idiosyncratic designs are not necessary nor valuable. The big shot schools of architecture that Wolfram visited will be made irrelevant by Wolfram.
References:

Mathieu Helie – Complex geometry and structured chaos
Stephen Wolfram – The Generation of Form in A New Kind of Science
Christopher Alexander – The Process of Creating Life

A measure of urban connection

What does it mean for a city to be connected? And is there quality resulting from this property? Let’s define the basic node of a city as a doorway. (Not necessarily a building. A single building can have many doorways to separate spaces.) A connection is the distance from this doorway to the next node, that is to say the next doorway. A well connected city is a city where the distance from doorway to doorway is minimized, since everything will be easily accessible from the public space.

Shopping malls have mastered this aspect of cities. They tightly connect boutiques which are long and narrow together, and place large stores at terminating vistas such that their bulk does not create a connective void. They have even restored the practice of kiosks, placing them in the largely unused central width of their interior street. Every effort is made to prevent holes from closed-down stores. Mall operators have found that when people run into such an absence of connection, they turn around, making a chunk of the mall unattractive and isolated. Since the mall exists to allow separate shops to benefit from each other’s proximity, it is terrible business to have such a hole in the network.

The concept of the suburban shopping mall is a reactionary invention. When urban planners defined the new city as being strictly automobile-based, some clever businessmen found it worthwile to restore the city street as an enclosed megabuilding, (what Leon Krier would call a landscraper) offering the connective value of the traditional city to otherwise stranded suburbanites. And the only way they could slip it by the planning authorities was to wrap it around a massive shell of parking. As such, although the mall’s interior street is an extremely well connected public space, once you exit that street the measure of connection drops close to zero. While you can walk in the mall from one doorway to another in a few seconds, to reach another doorway after leaving the mall may well take several minutes. (And you’ll almost certainly need to take your car.)

The most basic thing a city can do to build connections is create sidewalks from doorway to doorway. Humans move on foot. Everything else is just a shortcut.