City as Terrestrial Crustacean: Structural Engineering and Resilient Cities

On September 26, 2017, I was the featured speaker at a conference sponsored by the National Academies of Sciences, Engineering, and Medicine. The topic was “The Role of Advanced Technologies in Structural Engineering for More Resilient Communities.” I was asked to address the question, “what are cities thinking about and expecting from technology and structural engineering regarding resilience?” Here’s and excerpt from my remarks. The entire address can be found here.

Tech Wksp – Paul Brown from The National Academies on Vimeo.

In response to your question, my short answer is: Cities need your help reinventing urban policies, decision-making, and governance for this new epoch we are entering — while you continue making the component parts of cities more durable, less energy-intensive, and smarter. Thinking at the highest level about how to drive rapid adaptation and agility into the ancient DNA of cities.

As engineers, architects, and builders we may be so attached to the idea that resilience is a design problem, we forget that cities are people, places, and processes that depend on the built environment but are not defined by it.

Cities evolve because of the collaboration and conflicts that exist among citizens, elected officials, local authorities, regulators, developers, businesses, and many other institutions – the long list of interests and stakeholders active in every community.

In a 2013 paper published in Science, Luís Bettencourt reported on his research to model relationships that might apply across all urban systems. He acknowledges the difficulties associated with simulating the behavior of urban systems right up front:

“Despite the increasing importance of cities in human societies, our ability to understand them scientifically and manage them in practice has remained limited. The greatest difficulties to any scientific approach to cities have resulted from their interdependent facets, as social, economic, infrastructural, and spatial complex systems that exist in similar but changing forms over a huge range of scales.”

Bettencourt concludes his paper with the following observation: “although the form of cities may resemble the vasculature of river systems or biological organisms, their primary function is as open-ended social reactors.”

When asked in an interview what the heck that meant, Bettencourt replied (referring the city), “it’s really its own new thing, for which we don’t have a strict analogy anywhere else in nature.”

Despite Bettencourt’s caution that there is no good analogy for a city found in nature, I’m going to fall back on one to make a simple point. Let’s imagine the city as a land-based crustacean — like a crab or a terrestrial lobster.

As cities, we nest in locations accessible to water and occasionally subject ourselves to the threat of drowning. We grow a complicated exoskeleton that adheres itself to solid surfaces, extending rigid linear arteries in all directions that transport food, water, and goods into the guts of the city, and then carry waste products away.

As engineers, architects, and builders, we have an important role on this “land lobster.” We oversee the exoskeleton, including pincer and crusher claw design, construction, operations, and maintenance. Of course, the living heart and body of the city is inside the exoskeleton. It has no observable shape other than its eyes, antennae, and shell. And the living city takes the exoskeleton entirely for granted — never really thinks about it.

Now what if our habitat changes radically, and we need to quickly become more flexible, agile, and shape-shifting like say an octopus? How can that possibly happen? Probably it needs to happen from the inside out, gradually over time. Progressive changes in the city’s DNA, rather than cosmetic surgery on its shell.

But that doesn’t mean that those of us assigned to the “shell engineering” have nothing to do but wait for evolution to takes its course. Assuming we know the new objectives of flexibility, agility, and rapid response to unexpected attacks, maybe we do research and development on adaptation itself, on how to re-engineer the periodic molting process to improve mobility for example.

We need to encourage the acceleration of our evolution as cities and embrace the challenge of needing systems that are multi-purpose, durable, flexible, regenerative, and possibly “anti-fragile” (to use a term coined by Nassim Taleb).

We could work on system components that comply with the Department of Defense’s elegant definition of system resilience:

“A resilient system is trusted and effective out of the box, can be used in a wide range of contexts, is easily adapted to many others through reconfiguration and/or replacement, and has a graceful and detectable degradation of function.”

The good news is we are not locked in a shell, and the shape-shifting capacity of our cities is remarkable, when they show the political will to do so.

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