slide share presentation on emergent cities
The role of urban complexity in the practice of urbanism
Emergent Urbanism
Mathieu Hélie
Translated from the original French
Urban complexity theories
Since the 1990’s, many complexity science programs have researched urban complexity.
Pierre Frankhauser
French geographer Pierre Frankhauser studies the geometry of urban areas to determine their fractal dimension.
Bill Hillier
A spatial configuration theory, Space Syntax predicts the probability of traffic in the urban network, and some land uses
Michael Batty
Cities and Complexity is the biggest treatise specifically on complexity science applied to cities. (Cellular automata, agent-based models, mathematical equations, etc.)
No conclusion. The author admits that it is only an exploration.
Nikos Salingaros
Urban web theory, a physical connection network
Definition of a fractal city
What’s it for?
Up to now no theory attempts to explain how or why cities are complex and/or emergent.
No link to the process of urbanization.
« We want to know how to do our job »
History of urbanism
Solutions to scale problems that appear whenever the city grows larger
Organic urbanisation
The collapse of the Roman Empire ends the first attempt at urban planning
For the next 1000 years urbanization is a random unconscious process
Cities grow « organic » morphology
Characteristics of organic urbanization
Land is built up as the economy necessitates
Economic conditions change too slowly for change to be noticeable
No interventions other than a code limiting new construction
Organic urbanization still exists!
Where no planning system is enforced organic urbanization procedes naturally.
Pre-industrial planning
In the 17th century some towns reach hundreds of thousands of inhabitants
The organic network becomes jammed
Urban planning is (re)invented
Examples
The grid
New law codes regulate property division to maintain a uniform grid for traffic circulation.
Usage zoning is not adopted yet
Code of the Americas, New York, Torino, Barcelona
New York
Multiple grids collide into each other until the Plan of 1811 settles the entire island
The metropolitan scale
The regular grid is impossible to navigate with hundreds of streets
Cities routinely reach a million inhabitants
Transportation systems multiply and clash with each other
Architects provide the answer
The modern city will be a utopia planned with industrial science to build the city of the machine civilization.
The city is designed at the scale of millions of inhabitants
Characteristics of urban planning
The network is planned as well as the land uses through architectural building plans and zoning codes.
City plans become architectural designs
Scale problems of urban planning
Cities sprawl out
Social, economic and ecological problems
How can we make sustainable cities?
Evolution of urbanization processes
As we progressed to modernity the process of urbanization became less spontaneous and more industrial.
How did this impact urban complexity?
General theory of complexity
Stephen Wolfram, A New Kind of Science
Christopher Alexander, The Nature of Order
The Wolfram method
Observing nature allows us to formulate theories of natural laws
We have to guess these laws and test them with experiments
Observing the computational universe allows us to know the precise laws exactly
Wolfram’s classes of phenomena
Type I: dead
Type II: linear or regular
Type III: fractal hierarchical
Type IV: fractal random
Type II urbanization
Type III urbanization
Type IV urbanization
Alexander
Emergent processes are the key to natural or « organic » morphology
“I believe that the whole idea about the natural environment has been turned on its head actually in a very strange way. For about a quarter of a century, people have been in effect obsessed with saving the environment - which is of course a very sensible thing to do when it's being ravaged and destroyed.
But the real problem is that we won't be OK, in terms of building or in terms of nature or anything else, until we learn how to make nature.”
Morphogenesis
The form of a living system is the result of the reiterating local actions of elements following shared geometric rules. (DNA, physical law, computer programs)
Emergence of urban order
A single geometricruleregulates the growth of randombuildings
Morphogenetic urbanization
Dividing and subdividing land into a city works on the same principles as natural cell division
The complexity of the urban system depends on the number of actors in its production
Actors reuse the same geometric rule when growing the environment
Comparison to modern planning
The plan sets up a scale for the city
The developer decides the size of lots
The builder imports building plans from wherever
Inhabitants decide nothing at all
Result:
Emergenturbanism
Rethink the role of the homeowner in house building
Rethink the role of the developer in subdivision
Rethink the role of public works in the network
Rethink movement entirely
Shape grammars
Sell a building system instead of a building plan
Subdivision
Lots are drawn and selected on the fly instead of being subdivided in advance
The complex grid: village
The complex grid: town
The complex grid: city
SharedSpace
De-signalize public space
Replace control withnegotiation
Obstacles
Planning regulations
The permitting system
The banking and financial system
Political habit
Fractal government
Government is affected by scale problems when the metropolitan scale is reached
Merging contiguous communities is not always a viable solution
Fractal scaling provides an interesting template
Paris-Métropole
Conclusion
Complexity means solving problems at every scale
Emergent geometric rules are necessary to create complex cities
Each aspect of the urban development process must be redesigned
