Black Swans and Redundant Cities

Swine flu: legitimate global emergency or 24-hour Internet culture’s flavor of the weekend? Regardless, the story suggests that it’s getting easier and easier to view cities through the lens of risk and disaster preparedness. The past decade’s biggest news events—Hurrican Katrina and 9/11—both revealed key weaknesses in our most beloved cities’ infrastructure. Furthermore, Where has recently examined the nature of urban disasters and the importance of mitigating their impacts, along with the need to guarantee the provision of urban food and housing.

Cities and the people who inhabit them are inherently vulnerable. Urban environments depend on the basic means of survival—food and other resources—coming in from their hinterlands, while large populations living close together amplify the impacts of natural and manmade disasters (as Peter pointed out).

Faced with these risks, cities need to be more redundant. That is, critical urban systems like transportation and public health must become as reliable as possible by depending on more than one component. If one road goes out in an earthquake, there should be alternate routes. If one levee breaks, there should be multiple backups to protect a city from flooding. If a primary water source becomes contaminated, an alternate source should be ready to start pumping. In many cases, cities already achieve this. Modern road networks, for example, are among the most redundant systems in existence.

Redundancy is widely considered necessary in certain fields, like civil engineering, but it’s shockingly neglected in others that are equally vital. Nassim Nicholas Taleb has recently blamed the financial system’s meltdown on a lack of redundancy—everything depended on rising home prices and easy credit, and when those fell short of expectations the failure cascaded throughout the economy. There was no backup plan.

Taleb’s best-known metaphor is the Black Swan (also the title of his last book). Black Swans, Taleb writes, are fundamentally unpredictable based on past events but have potentially huge impacts. 9/11 may have been the quintessential Black Swan—it could not have been more catastrophic, and lacked any precedent that might have facilitated preparedness. Our civilization can best prepare for the Black Swan, Taleb says, by grasping our limited ability to predict and by making decisions that account for the unknown.

For the urbanist, this means building and maintaining resilient and redundant cities. It may have been impossible to predict the exact circumstances that caused New Orleans to flood. It’s not impossible, however, for urban citizens, communities and city officials to understand the vulnerabilities particular to their own city and to build a more resilient urban environment on the basis of that understanding.

(Photo from Flickr user mariemassacre.)


Patrick said...

Would you say this redundancy is similar to Christopher Alexander's idea that cities are overlapping networks of patterns (see "The City is Not a Tree," "The Timeless Way of Building")? It seems that his vision of a "whole" city is one that has many redundant, but individually unique networks.

Drew Austin said...

Patrick, I think the notion of redundancy is supported by Christopher Alexander's ideas. Cities are certainly made up of many overlapping networks and systems; ideally each of those systems would support each other rather than working in isolation (or being treated as such).

Jarrett said...

In its connotations, isn't resilience a batter term than redundancy? I think the latter term strikes the layman with a range of unwanted connotations: the redundant as something unnecessary. Redundancy in Commonwealth countries is also a euphemism for layoffs.

Resilience, I think, is a better term for exactly the quality you're discussing.

Manu Fernández said...

By the way, I have just read this: http://www.kiplinger.com/magazine/archives/2009/07/best-cities-2009-where-the-jobs-are.html