The pros and cons of population density in general and in times of disaster

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Gov. Andrew Cuomo of New York was blunt about the rationale behind this time of quarantine.

“There is a density level in NYC that is destructive,” he tweeted Sunday, after similar comments at one of his daily press briefings. He’d seen New Yorkers out in parks together, behaving as if this were a normal sunny spring weekend, and he was dismayed. Togetherness itself could now be deadly.

“It has to stop and it has to stop now,” he tweeted. “NYC must develop an immediate plan to reduce density.”

This has been an especially painful realization in major cities: The very thing that makes cities remarkable — the proximity of so many people to one another — is now making them susceptible in a pandemic. Density, suddenly, is bad for our health. And we are trying everything we can think of to dismantle it.

Special grocery store hours for older people — those are about reducing density. Closed schools and dispersed children — the same.

 

Telework is the least dense version of office life; takeout the least dense way to eat someone else’s cooking. Governor Cuomo has even suggested opening roads normally reserved for cars to pedestrian traffic. An empty street is the least dense way to walk somewhere, even in a seemingly empty city.

What feels so disconcerting about this is not just that density normally brings urban perks — diverse restaurants, rich cultural institutions, new business ideas — that we can’t enjoy right now. Even more than that, density, in the right conditions, is good for us. It even protects against other kinds of calamities.

Density makes mass transit possible. It allows for more affordable housing. It creates environments where people can walk and where children can find playgrounds. It enables us to pool risks. It supports big public hospitals and stronger safety nets. It allows us to curb climate emissions, which present a public health problem of an entirely different kind.

Crucially, it enables the kind of redundancies that make communities more resilient during disasters.

How, then, do we reconcile the benefits of density for a healthy society with the threat of density in a pandemic? And what happens if we lose sight of those benefits — including the ways they are operating even now — while we are preoccupied by the harm?

Since the 1990s, researchers and planners have increasingly come to argue that dense urban environments, derided historically as diseased, can actually foster health. They don’t mean overcrowded tenements, but places where people live close enough to one another to walk where they need to go and to support one another. Such environments offer an alternative to sedentary, car-dependent sprawl, an antidote to growing health problems like obesity.

“This does feel like something that’s going to set all of that back a little bit,” said Sara Jensen Carr, a professor of architecture, urbanism and landscape at Northeastern University. She is working on a book, due out this fall, looking at how urban landscapes have been designed in response to epidemics, from cholera to obesity.

Cholera outbreaks helped lead to the design of modern sanitation systems. Respiratory diseases in the early 20th century encouraged city dwellers to prize light and air, and something that looked more like country living. Now Ms. Carr worries that the coronavirus may teach people to further fear density, even in the form of new housing proposed nearby.

But if the earlier history of American cities is full of public-health horror stories about substandard housing, factory pollution and poor sanitation, more recent history tells of the health and resiliency density can provide.

In practical ways, density makes possible many of the things we need when something goes wrong. That is certainly true of hospital infrastructure — emergency response times are faster, and hospitals are better staffed in denser places. When one store is closed or out of toilet paper, there are more places to look. When people can’t leave home for essentials, there are alternative ways to get them, like grocery delivery services or bike couriers. When people can’t visit public spaces, there are still ways to create public life, from balconies, porches and windows.

When New York’s subways were inundated during Hurricane Sandy, the city could lean on its bus system (made possible by density). And now that the buses seem off-limits, the city’s bike-share system offers backup (that also exists thanks to density). When all else fails or floods or shuts down, walking is still possible in New York and Washington, San Francisco and Seattle. And many of the things people need are close enough to walk to.

Atlanta illustrated the opposite lesson in 2014, when two inches of snow brought the entire region to a standstill, trapping tens of thousands of people in highway gridlock, some for 12 hours or more. The region, critics pointed out, had for decades failed to invest in a transit system that could have offered an alternative to those highways — and in the density that could make transit viable and highways less essential.

Hurricane Katrina survivors displaced to more walkable communities around the country later showed signs of health benefits. Older Chicago residents in the 1995 heat wave were more likely to survive in neighborhoods dense with neighbors, stores, public spaces and street life.

“Dense social networks in communities save people,” said Jacob Remes, a historian at N.Y.U. who has studied urban disasters. “That’s what makes communities resilient, and it’s what then helps communities recover.”

But it’s unclear how we’re supposed to leverage all those dense connections this time.

“What does that look like when the thing we have to do is stay apart from each other, when what we need to do is further isolate ourselves?” Mr. Remes said. “I don’t know. I don’t know what the answer is.”

One hopeful note is that Singapore, Hong Kong and parts of Taiwan, places as dense or denser than New York, were able to pursue early testing and extensive tracing of coronavirus cases rather than widespread isolation.

Mr. Remes, Ms. Carr and others are also sure of this: It will be a shame if we come away from this moment skeptical of density itself, or if some of the benefits of density, like mass transit and bustling commercial corridors, suffer lasting damage. Whether or not we fully appreciate them right now, we may need them in the next disaster.

Why it’s hot: Will there be a move away from walk-able neighborhoods and dense cities for businesses and young people in the post Covid-19 world? Will there be greater migration into suburbs for both businesses and people? Will this affect housing, building, and transportation patterns in the years to come?

Source: New York Times