Effective Quarantines and Strong Towns
Image by Leon Krier.
Image by Leon Krier.
The images above are related and I’m going to explain how, but first I want to start with a personal anecdote. My siblings and I have always loved playing with dominoes to create intricate chains that snake around the house. After setting up the course, we would watch as the first domino toppled into the second, creating a chain reaction that was mesmerizing.
One thing we learned quickly through our domino creations was the importance of introducing regular breaks in the chain. The purpose of these was to isolate the effect of an accidental fallen domino or an ill-placed footstep. Without breaks, a single stray piece could completely destroy our creation prematurely. Only after each section was complete would we bridge the gaps to unify the whole.
This same thinking is present in many systems. Firefighters use firebreaks to slow the spread of wildfires. Builders use firewalls to prevent or slow the spread of a building fire. You are likely familiar with this principle in your own life in some form.
Right-Sizing a COVID-19 Response
In this era of COVID-19, the concept of isolation has become ubiquitous as we all hunker down at home hoping for the pestilence to pass us by. The current response in most places has been unnecessarily slow and inadequate. In an odd way, current measures have also been at once overly restrictive and too permissive. As with many of the issues that modern society faces, the root of this dichotomy is an inability to appreciate scale in solving problems.
Let’s go back to one of the images above:
This visualization is actually part of a study conducted by researchers at the New England Complex Systems Institute in the wake of the Ebola virus. The authors modeled the outbreak of a virus in individuals (represented by cells in the grid) and various strategies for containing and extinguishing the threat. In the visualization, which illustrates the most effective response, you can see the early stages of the outbreak as a few random points become infected and begin to transmit the disease to neighbors. The moment when the image explodes with orange represents the point at which travel restrictions are imposed. Each large square is bounded by impermeable borders that disallow travel (and therefore virus transmission) between communities. Like the break in my dominoes, the travel restrictions ensure that an outbreak in one community is contained without spreading to a nearby community. It also allows authorities to focus resources on affected communities, avoiding the need to spread already-strained resources to areas where no outbreak has been identified.
The key takeaway from the study is that applying restrictions at varying scales is vastly more effective at containing an outbreak. It is also vastly less demanding on people in communities where no outbreak is active. As an added bonus, the scale-dependent response is effective even with low rates of compliance. In the simulation, even if 60% of the population refuses to comply there’s still a dramatic reduction in the rate of spread (and therefore the time needed to return to normal life). To illustrate this, imagine if travel restrictions to and from China had been imposed at the early days of the outbreak. The disease has effectively been contained in China now and the rest of the world could be going about its business, with China starting to re-open its borders. Closer to home, imagine if my state (Washington) had shut down movement between counties as the outbreak took hold in the Seattle area. Even as I write there are counties with no confirmed cases and yet these residents are subject to the same stay-at-home orders as those living at ground zero.
As Joseph Norman, Yaneer Bar-Yam, and Nassim Taleb articulated very early in this crisis (note the January publish date), the sooner we act, the smaller the costs are. We’ve waited too long already, but there’s still time to limit the scope of destruction by implementing scale-aware restrictions.
Travel Restrictions and Strong Towns
Much has been made in recent weeks of the supposed superiority of suburbs over central cities in a pandemic because of lower population densities. As usual, this discussion completely misses the point. First, let’s establish that in terms of social interactions that can lead to disease transmission, the differences between a typical suburbanite and a typical city dweller are not appreciable at the scale of a global pandemic. Both people are making trips to the grocery store, offices, restaurants, movie theaters, and other places where large numbers of people pass through, not to mention that many suburbanites commute into city centers for work and entertainment.
Rather than density, the important question relates to whether your place resembles a complex ecosystem or a complicated machine. And now we come back to the others illustrations from the top by famed architect Léon Krier.
Image by Leon Krier.
Image by Leon Krier.
Our predominant mode of thinking over the last century, afflicting cities and suburbs alike, favors highly centralized systems that prize efficiency over resilience. We see this in the left image representing “overexpansion.” This city exhibits two extremes: intense development in the core surrounded by uniform, sparse development far into the periphery. The functional unit of this city—the smallest recognizable area you could divide the city into while maintaining similarity with other cities and other scales of human habitat—is effectively the entire city or region. There’s no way to divide this up further without leaving out something crucial to the idea of what a city is.
The image on the right is characteristic of a complex habitat. Although some parts are more densely built up than others, there’s no one monolithic center. There’s a rhythm to this city. The functional unit here is the neighborhood, each with its unique character and hub of activity, but all of them exhibiting high levels of self-similarity. This city grows through incrementalism and duplication—a new area at the edge develops over time into a coherent neighborhood and seamlessly stitches together with the rest of the urban fabric. It is also highly resilient. You could shut down an entire neighborhood without significantly impacting other neighborhoods because services and amenities are distributed as part of the duplication process rather than centralized in one district. Your body understands this too, which is why you have two kidneys.
And now we come to the connection between these two ideas. If you’re faced with viral transmission of a deadly disease, the most effective way to stop the spread and stamp it out is to solidify borders at varying scales to contain the outbreak. If your city, region, state, and nation is highly centralized, solidifying borders and reducing travel can be fatal. A centralized system requires high levels of movement to ensure distribution to all parts of the system. Ask yourself: if my city had to cut off my neighborhood temporarily, could we survive? If my city had to cut off our downtown, could we survive? If my state had to cut off my region, could we continue?
Our world is connected globally at a scale and speed that was unfathomable until the 20th-century. With that connectivity has come increased centralization at all levels and in virtually all facets of life. The result is a system that is extremely efficient for getting you cheap toilet paper, low-cost calories, and fast cars—until it’s not. It’s also a system that is extremely fragile, optimized for distributing a deadly disease rapidly and completely while maximizing the cost of isolating outbreaks. A Strong Town prizes the resiliency that comes with incremental duplication, over the short-term gains that come from hyper-efficiency.
Spencer Gardner has been writing for Strong Towns since 2016. He is a transportation planner based in Spokane, WA, who spends his spare time chasing his children, riding bikes, and doing hobbyist computer programming. He's also getting started on his own missing middle development project in Spokane's West Central neighborhood.