Urban seeding and the city as computer

Here’s another take on a kind of peer to peer approach to urbanism, from an advance draft sent to us by Nikos Salingaros.

Despite the complex sounding title, this is an entirely accessible essay:

“Geospatial Analysis and Living Urban Geometry” By Pietro Pagliardini, Sergio Porta & Nikos A. Salingaros. To appear in: Bin Jiang and Xiaobai Angela Yao, Editors, Geospatial Analysis and Modeling of Urban Environments: Structure and Dynamics, Springer, New York, 2009.

The abstract states the starting point of the approach very clearly:

We condemn the high-rise tower block as an unsuitable typology for a living city, and propose to re-establish human-scale urban fabric that resembles the traditional city. Pedestrian presence, density, and movement all reveal that open space between modernist buildings is not urban at all, but neither is the open space found in today’s sprawling suburbs. True urban space contains and encourages pedestrian interactions, and has to be designed and built according to specific rules. The opposition between traditional self-organized versus modernist planned cities challenges the very core of the urban planning discipline. Planning has to be re-framed from being a tool creating a fixed future to become a visionary adaptive tool of dynamic states in evolution.”

The authors state that what is needed is an entirely different approach, that abandons top down planning:

We are not speaking about the failure of a set of theories, or even single or a group of architects and planners: it is the failure of an entire discipline, which originated at the end of the nineteenth century around ideas of top-down control. Urban phenomena have now been recognized as enormously complex and therefore inherently uncontrollable from the top down. We do not just need better architects and planners: we actually need architects and planners of an entirely different kind, who take the challenge of self-organization in cities seriously enough to investigate new forms of description, prediction, and intervention. Especially, we need a broader awareness that all this has nothing to do with style and everything to do with structure. The process of spatial evolution in traditional cities has always been unplanned, and so it must be in part for good future cities. Planners have to focus on the structural drivers of such evolution in order to manage the seeds of change, and not try to control its final state.”

Here’s a more detailed outline of their critique:

The main misunderstanding with today’s urban form is that planners mistakenly believe that priority must be given to the fastest automotive traffic (Hall, 2008). This error in thinking precludes planning for all the myriad small-scale movements and slow flows necessary for a living city. Another casualty of this approach is that, as a general principle, flows are made to erase stationary places such as plazas and parks that combine tangential pedestrian flow with pedestrian nodes. Those spaces must be protected from street traffic (Salingaros, 2005).

Modernist planning is by its very nature devoted to separation. That practice draws back upon outdated scientific thinking (from which modernism claimed its roots), which in fact cannot deal with complex systems (Porta, 1999). Cities, like organisms, are the prime examples of complex systems. Separation is nevertheless the gospel in every aspect of modernist theories on cities; therefore, separation of urban space users is just an application of this attitude to over-regulating urban life. One example of this, in addition to squares and parks, is the boulevard. Boulevards successfully combine rapid mechanical flows, slow mechanical flows, pedestrian flows, pedestrian stationary nodes, etc. (Jacobs et. al., 2003). Boulevards were legally banned at the beginning of the 20th century because they were complex spaces that gave place to different kinds of networks altogether. A healthy mix of social classes and uses is obtained first of all by having an urban design that allows such a mix to occur. There exist distinct approaches, all converging towards a type of urban form that brings us back to the great historical city tradition.”

But can we actually know these rules. The authors affirm that this is indeed the case:

This characteristic ribbon geometry of urban pedestrian space follows very simple rules (Salingaros, 2005):

1. A city’s life is the direct result of pedestrians using its public urban spaces.

2. Urban space is an open container for crisscrossing footpaths, protected from, but at the same time connected to all other forms of transportation.

3. Urban space also provides the setting for the crucial human contact with nature.

4. The function of building fronts is to enhance the enclosure and informational properties of urban space.

5. All urban space is connected in a pedestrian network: sidewalks simply widen out into plazas.

6. A street is urban space that allows itself to be traversed by vehicular traffic, sacrificing pedestrian space locally in exchange for connecting pedestrian space globally.

7. Where the pedestrian network crosses another transport network, pedestrians must be protected by the physical structure itself.

8. When a city doesn’t provide living urban space, private developers will do so, but then it is disconnected from the urban fabric.”

To put these principles into practice, what is needed is a practice of urban seeding, instead of urban planning:

““wholeness” (Alexander, 2001-2005; Alexander et. al., 1987) … can only emerge and cannot be designed in cities, we need new practices for the description, prediction, and transformation of urban spaces of an entirely different genre. This different approach, which we term “urban seeding” instead of “urban planning”.

This calls for a ‘neo-traditional’ approach, that doesn’t just look at the past of premodern living cities, but uses the new technology for its capacity to uncover living patterns:

In short, GIS helps to develop a much deeper understanding of key factors that rule the emerging spatial order at the structural level of city evolution. Up until very recently, this extremely important factor has been elusive because of our limited methods of measurement. Gathering and processing data on human behavior in the past required very costly video cameras set up for weeks in a particular spot (Whyte, 1988). Now, we can display an enormous amount of data in visual form, processed in various ways that reference geographical locations in space by means of remote sensing techniques associated with GIS (Senseable City Lab, 2006). Discovered patterns of use that confirm earlier theoretical results can be used as the basis for a radical re-organization of urban use and government policy. Where strong connections are concentrated only into a few channels, and if those channels are exclusively long-distance, then the urban morphology must clearly change to encourage shorter connections.”

With such visualation at our disposal, the following method can be used:

As we accumulate data on pedestrian presence and movement, we can pick out and classify those urban regions where people can be found. Then, we can follow movement to plot frequency and length of pedestrian trips. For example, the front entrance to a suburban house is rarely used, remaining an expensive and stubbornly decorative architectural element. On the other hand, traditional urban space in historic cities, and open spaces in owner-built informal settlements (favelas) both attract an incredibly high density of human presence. Studies establish correlations between human presence and the shape of urban space (Salingaros, 2005). Those spaces are alive, providing paradigmatic urban environments of a living city. There is a growing interest in technologies for the remote sensing of people in urban spaces and for tracking the movement of persons in sectors of cities. There is more experience for small groups of people in small places. ”

The authors propose a new metaphor that is distinct of both the ancient and modern city visions, i.e. the city as computer:

The “city-as-computer”, distinguishes the two parts of any computing system into hardware and software (Salingaros, 2005: Chapter 7). A computer is clearly separated into its physical components (as built), and its software (which is strictly informational): each relies upon the other to work together. In a city, hardware is built into solid structures (buildings, roads, infrastructure, etc.) whereas software consists of the moving elements (people, cars, goods, energy, etc.). A city provides the solid framework upon which movement of information (the analogy to software) can take place.”

Distinguishing strong and weak network links is useful as well:

As described accurately by Hillel Schocken in his essay “Intimate Anonymity” (Schocken, 2003), human beings have a craving for community, and it could just as well be a community of strangers. Seeing other people up close has a biologically beneficial effect on our organism (Kellert et. al., 2008).

This is one aspect of biophilia: we crave intimate contact with plants, natural environments, other animals, and other human beings. We cannot satisfy this need for contact with only our close friends, thus the traditional urban environment of non-threatening strangers turns out to be a key factor in an emotionally-nourishing city (Oliva-i-Casas, 2001).

Scientists point out the importance of weak links between networks that are strongly connected internally (Granovetter, 1973). Those weak links tie distinct networks together into a larger network. We interpret this mechanism in the urban context as follows. People have a strongly-connected network supporting their everyday life. Strong connections do not necessarily mean nearby ones, however (a drastic reversal from village life). We could be telecommuting, working for a company in another city, or driving our children to a good school far from home. Those distant links are the strong ones. The weak links in this case could be the persons and urban nodes close to one’s own residence or workplace. Opening up the possibilities for casual contact and pleasurable direct experience outside one’s normal routine is what makes the city alive.

Unlike in the modernist planning philosophy, where behavior is strictly imposed on the population, we are referring to creating situations that make individual choice possible. We wish to facilitate the random exposure and contact with other human beings, which in a properly designed urban environment is not chaotic. Gathering of people as well as spatial changes at the micro-scale of the urban structure are not pre-determined by anyone else, but they are influenced by urban geometry and spatial morphology.”

There is of course a lot more of interest in this essay, but here is their conclusion:

We have inherited a rich variety of invariant patterns for urban structures. These have changed very little from what we see in traditional settlements, so we can apply those typologies to generate living urban structure today, i.e., a type of urban fabric that fosters the informal human exchanges which generate “life between buildings” (Gehl, 1996). Living urban fabric evolves with time through countless unplanned and unpredictable grass-roots contributions by citizens and social actors at all scales. The problem is that most architects and planners, influenced by decades of anti-traditionalist practices, have forgotten the morphology of such living urban structure. In fact, the discipline of architecture and urban planning itself as we know it needs to be substantially re-framed in a new “urban seeding” approach, so as to embrace the idea of self-organization as a key feature of successful urban spaces. Lacking those insights, whenever arrogant modernist and “star” architects try to design urban fabric today, it turns out to be dead. Those who argue most fanatically against the use of traditional forms are ironically the same persons who defend the deadening sameness of the sterile modernist forms they wish to apply for every case and for every locality. The diversity and adaptivity of traditional typologies is our guarantee against homogenization. There exist common bases, biological and perceptual, for any architecture and urbanism, and every human being can verify if those are adaptable to our living environment. We change the forms, following changing cultural traditions and needs, in which the common rules of behavior are manifested. What remains invariant, however, is the biological perception common to all people. ”

Request the full version from Nikos Salingaros, email: yxk833 at my.utsa.edu

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