"The New American Dream Is Living in a City," Time magazine declared -- just one of the thousands of think pieces over the last few years about why young people today are choosing to live downtown, where they can have diverse experiences, inhabit public spaces and walk everywhere they need to go.
That certainly sounds like lovely way to live -- healthy, connected and car-free. Unfortunately, residents many urban neighborhoods have been experiencing a different reality.
The truth is, many urban neighborhoods are effectively cut off from their cities by highways, constraining access to jobs and public services for the residents who live there. These highways may pose a health risk, too: studies from the Centers for Disease Control and Prevention and the Environmental Protection Agency suggest air pollution from traffic can exacerbate health issues for those living, working or attending school near major roads.
It's taken almost 60 years, but we are finally realizing the error we made when the United States built highways through the middle of its cities, displacing and isolating hundreds of thousands of residents, and we're beginning to do something about it.
US Transportation Secretary Anthony Foxx has made improving neighborhood connectivity and walkability a major part of one of his signature initiatives, Ladders of Opportunity. But as Charlie Sorrels noted in Fast Company, even Foxx can't rip out highways that are already there.
But local leaders can. In fact, cities all over the world are removing highways, rail lines, and other disruptive or derelict transportation infrastructure and replacing it with linear parks.
Here in Boston, near my home, a section of I-93 running through the middle of downtown was converted to the Rose Kennedy Greenway, a string of parks that reconnects some of Boston's oldest neighborhoods. New York's High Line, a converted industrial rail line, is perhaps the most famous example in the US, attracting 5 million visitors every year; the Cheonggyecheon Stream recreation area, the former site of a downtown highway in Seoul, South Korea, sees 64,000 visitors a day.
Greener Cities are Healthier Cities
Linear parks are more than just tourist destinations, though: they offer wide range of benefits to city residents and to urban wildlife, too. There is growing body of research suggesting that being around trees can actively improve one's mental health, and some studies show that children learn better in schools located near vegetated areas. New research from the National Institutes of Heath suggests that living near vegetated areas can actually reduce mortality, perhaps because people in these areas get more exercise and social interaction.
Parks and other vegetated spaces also reduce the urban "heat island." In Seoul, the effects are quite dramatic: temperatures near the Cheonggyecheon Stream can be 3.3 to 5.9°C cooler than temperature along roads four to seven blocks away.
Removing highways doesn't necessarily create traffic problems, either. Drivers tend to respond to "flexible demand": when there is more road capacity, more people drive, and there reverse is true, too. This has proved to be the case in Seoul--despite dire predictions, there's been little increase in congestion since the removal of the highway over Cheonggyecheon. Instead, more people are taking public transit, which has helped reduce air pollution in downtown--another health benefit.
Preserving Biodiversity
And it's not just people that benefit--linear parks can help preserve biodiversity in urban areas. Wildlife, too, suffers when habitats are fragmented and cut off from larger natural areas. Parks of any kind can offer refuge, particularly for migratory birds passing through urban areas, but linear parks are particularly beneficial because they often connect multiple parks and green spaces within an urban area. This creates "green corridors" that species can use to travel between habitats.
Linear-shaped parks also serve more people, as Dave Maddox explains at Nature of Cities. A long, narrow park provides more access than a square or circular park of the same area because it has a larger perimeter--more communities are adjacent to the park and more people live in walking distance.
The Future of Cities?
Highway removal and linear parks are major trends in urban design right now, but we can't let this just be a trend, something that passes from fashion--green spaces should remain a part of all our urban planning. And not just where there's a road or railroad that's easily removed. With the world's population rapidly growing and urbanizing, we need to start thinking deliberately about where we put parks. What if we made proximity to green space part of the planning for new schools?
In a recent speech about Ladders of Opportunity, Secretary Foxx suggested US infrastructure planning should be driven by one question: "What kind of country do we want to build?" I say, let's make sure its one where people and nature thrive together--and where the benefits of this relationship are shared with everyone.
Pascal Mittermaierhttps://global.nature.org/experts/pascal-mittermaier is the Global Managing Director for Global Cities at The Nature Conservancy. You can follow Pascal on Twitter @PascalMitter and learn more about his work at nature.org/global.