Emergent Urbanism

Rediscovering Urban Complexity

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.


Sustainable algorithmic design lecture series by Nikos Salingaros.


"We must invent the tool that makes it possible to see what is too large to see. "

I think you hit the nail on the head here. The problem as I see it is that the tools we have to do this, mainly maps, are inadequate and deceiving. Maps let planners see an area from above but in order for this to be possible all the information about the human interaction at street level is lost. Superblocks look great on a map because they simplify an area. The human element is never though of because it cannot be seen.

But what about interactive maps, such as Google Maps/Earth, that give you the ability to see places from many different angles at the same time? This seems like a step in the right direction. Maps aren't bad tools; they are some of the most useful tools ever invented. It just seems we are using them incorrectly, such as trying to cut a cake with a hammer.

If the problem of maps was the lack of information (which was really the point of maps, to show only the information you need), will maps showing total information be the answer? I don't think so, that is unless we just have real-time cameras at all places at all times.

I don't have an answer but I think this might be the right question.


Intriguing essay. I especially like your distinction between architecture and urbanism, and the characterization of urbanism as "emergent". There's one important correction, though. The SmartCode is not a building code - it is a zoning and subdivision code. Zoning and subdivision codes have long been used to guide the emergent nature of urbanism, and in fact, are one of the drivers of the highway-related urbanism that you describe. For more information about the SmartCode, please see http://www.smartcodecentral.com

The point I wanted to make is that a subdivision, by the way that it is produced and now the way it is administered as well, is indistinguishable from a building.

Andrew, maps show the large scale but they are still within the dimension of a single human mind. Cities are not built by a single human mind.

The military men make maps as well, but to see what happens in the emergent dimension, they run war games.

Does that mean we need to run city simulations? SimCity's if it were?

A couple of points/questions:

You say, "... New Urbanist TNDs are no different than the regular, economically-unsustainable subdivisions."

While there are indeed difficulties that the new urbanism faces as it tries to undo many decades of poor planning, it must be recognized that defining a new type of neighborhood is an initial step in the right direction. Will we ever be able to reverse what has been done in the suburbs? Absolutely not. But, does that mean we shouldn't try to salvage what we can? Following that logic then shouldn't we also give up trying to reduce our carbon footprint and minimize emmission of greenhouse gases?

You also say that flight to the suburbs was enabled by new urbanism. I’d love to hear the explanation of this, as this comment surely hasn't been thought through. If anything the new urbanism arose as a response to suburban sprawl. I would encourage you to read Suburban Nation, for more information on this.

To say that the SmartCode is "antimarket" simply shows that you have either never read the document or do not comprehend its inherent flexibility. The SmartCode designates building forms as they relate to their place within a community/town. While it does have some regulations regarding use, it is vastly more flexible that typical zoning codes. It allows for the adaptive reuse of buildings over time, which is something that has occurred in great cities worldwide.

I'm sorry a different Andrew but you are reading the opposite of what I have said.

nteresting essay; sorry to be coming to it so late.

I am certain you are onto something when you talk about the “emergence” problem of the New Urbanism.

It would be interesting to contrast the approach of TND development with the generative approach of Christopher Alexander and his colleagues. Not being a planner, I am hesitant to comment too specifically on the differences, but one thing seems to stand out: for all it's progressive ideals, New Urbanism has tended to rely on the conventional mechanisms of financing through big developers and banks.

Alexander's approach, by contrast, is more “bottom up” (as you know).

It will be interesting to see how these contrasting approaches will play out as the U.S. and the world as we continue in this period of dramatically contracting credit and we cross over into the post-peak oil era. We may be entering a period when nothing (or almost nothing) will be built top-down, and everything will be emergent, not by choice but by necessity.

You are developing some very interesting arguments here and it will be interesting to see them develop.

But, I wouldn't by any stretch of the imagination define Mackenzie Town as New Urbanism. Maybe the developer is calling it that, but it is just dense connected sprawl as you say. There are no uses other than housing visible, and the road layout is essentially pods of unconnected groups of streets. That's not NU! You have a good argument, but you need to start with some good examples of NU to critique, not the developer dross shown here.

How about critiquing some CNU Charter Award winning projects? I'd be very interested in reading your analysis of those.

Also, if you look at the scale of Calgary as a whole, Mackenzie town is an additive chunk that shares many of the same structural qualities as the rest of suburban Calgary. So, it is emergent, but not at a fine grain, and not in the nice way that traditional Mediterranean towns were emergent.

Finally, I thought your response to Andrew (a different Andrew)'s post was too dismissive. The fellow has taken the time to comment, give him a good response!

Keep up the good work,


I'm afraid that McKenzie Towne is very much New Urbanist. It has a town center and blocks of homes with alleys to keep the cars off the street. It has many squares and a lake that creates a very large public waterfront. Honestly, from an urban design point of view, it is a great project.

If the uses tend to be overwhelmingly housing, that is just a normal consequence of the development model itself. You can't ask a developer to plan a real mixed used neighborhood; it is too complex a venture. It can only come from a large number of people growing around each other. You can mimic it by spending an enormous amount of money to subsidize the mixed uses, and in so doing win an award, but that is the opposite reason why someone like Jane Jacobs praised the mixed used neighborhood.

McKenzie Towne is the example that everyone uses who is trying to debunk new urbanism when it is not new urbanism at all and the photo you link to is proof. New urbanism is about the pedestrian and living and working in the same environment. The image you have shown is an outdoor mall whose access requires a car. Call it a "town center" or whatever you want its not new urbanism.

As Matthew points out critique a true new urbanist development like www.serenbecommunity.com then your analysis might have some merit.

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