Part 1:  What it is and why it’s in the news

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University of Michigan research finds that about a third of American homeowners would like to live in walkable urban neighborhoods such as those that comprise most of our city. But only 5-to-10% of metropolitan housing is located in such neighborhoods.

While demand for walkable neighborhoods is increasing across most demographic groups, it’s growing fastest among millennials—young adults born after 1980. 64 percent of them decide where they want to live, and only then look for a job. 77 percent say they want to live in an urban core. As this would imply, walkable communities have an advantage in attracting the most talented workers.

In its simplest terms, “walkability” is a measure of how much a neighborhood encourages, motivates, and supports walking. It’s a hot topic among city planners, developers, economists, government officials, and neighborhood activists.

Economist Joe Cortright has coined the term “walkability dividend,” which accrues to cities that encourage walkable neighborhoods. He analyzed data from 94,000 real estate transactions in 15 major markets and found that walkability translates into higher home values. And walkable cities’ property tax revenues increase, because property values increase.

Their city services costs go down as well. Over decades, transportation planners have learned the hard lesson of “Induced demand.” When they try to reduce congestion by expanding traffic capacity, they get more congestion—and more cost.

Brookings Institution Fellow Christopher Leinberger is a developer as well as a scholar. He says that real estate and infrastructure development are in the midst of a structural change comparable only to what took place following World War II. “We in real estate are fundamentally re-tooling how we design, plan, regulate, and finance to serve this pent up demand” for what he calls, “walkable urbanism.”

Epidemiologists tell us that people live longer, healthier lives in walkable neighborhoods than in nonwalkable neighborhoods, and in cities and towns rather than in sprawl. They are less obese, have lower levels of diabetes, and suffer less cardiovascular disease. The American Cancer Institute says that urban design should encourage walking because it reduces cancer rates.

Sociologists tell us that walkable neighborhoods provide more opportunities for social interaction and their residents have more friends and associates. They also have greater pride in their communities and they volunteer more often.

Criminologists tell us that walkable neighborhoods have markedly lower crime rates.

Biological scientist Craig Stanford tells us that upright gait and walking have been vital to the development of the human brain, raising the question of whether a century of driving has made us stupider.

Climate scientists and climate-change advocates tell us that a New York City resident has one-fifth the carbon footprint of a Dallas, Texas resident. And exhaustively reviewing the scholarly literature, urban researchers Reid Ewing and Robert Cervero tell us that, “Almost any development in a central location is likely to generate less automobile travel than the best-designed, compact, mixed-use development in a remote location.”

For all these reasons, walkability is an essential focus of the city’s Somerville by Design Initiative, a participatory effort to conserve neighborhood character and wisely plan the areas around new Green Line stations.

Consider a lover’s stroll from the Somerville Theater to the Rosebud Diner in Davis Square versus one from the Somerville Avenue Target Store to Twin Cities Plaza. In the former, the built environment participates in and enhances the experience. In the latter, the environment constrains and disrupts the experience. Thinking about why goes a long way toward understanding what makes for walkability.

Perhaps the most important factor is having someplace to walk to, and through. In Made for Walking, Julie Campoli illustrates how walkable neighborhoods offer a density and diversity of such places—restaurants, health services, retail financial institutions, stores, civic functions, entertainment, recreational facilities, schools, jobs, parks, and transit stops, all in walking distance.

Given desirable places to get to, walkability requires a means of doing so. This involves a density of street and path connections with many short links and many intersections. In other words, something like Somerville’s street grid.  It also involves easy access to transit that will take a walker to places of interest outside the neighborhood. We enjoy a reasonably good bus network, and the Green Line will further increase the walkability of Gilman Square, Magoun Square and Ball Square.

Walkable streets must be appealing. Threshold requirements are safety, cleanliness, and an acceptable level of noise, but they are not enough.

Perceived “walking distance” varies greatly depending on how comfortable, interesting, and engaging the walking environment is. Urban designers use terms like “human scale,” “sense of enclosure,” “imageability,” “transparency,” and “complexity.”

The more interesting the view and the more it changes, the more people will walk, and the longer they’ll walk. We like structures that are built out to the street, with lots of doors and windows. We like architecture, design, and streetscapes that are pleasant to look at and be in.

We like other people on the street. We’re social critters. We enjoy observing others of our species, and their presence suggests that we’re in a good place.

We’re more comfortable when we feel sheltered, by building height, or trees, or canopies and overhangs. Outdoor seating and places where we can linger increase walkability. And of course, one or more good bars is a must.

In my next column, I’ll talk about how cities, businesses, developers and residents create walkable neighborhoods and what we can learn from them. Cities on the leading edge of this movement aren’t just those we might think of as “trendy.” Cincinnati, for example, has produced a comprehensive plan that funnels growth into 40 walkable “Neighborhood Centers.”

Somerville enjoys a big head start, not because we’re so clever, but because our ancestors built a city around people rather than around the automobile. Jeff Speck is a “new urbanist” whose Walkable City book has garnered huge attention this year. Retained by the city as a consultant, he tells us, “You are already ahead…. You were born on third base.”