On this street in Washington, D.C., old and new stand harmoniously side by side.Photo: Dave Reid

Jane Jacobs celebrated mixing the old and the new together, so much so that she considered it one of only four principles of good urban form. If a neighborhood is all old buildings, it’s either a staid museum piece for tourists or a victim of severe economic disinvestment. If a neighborhood is all new buildings, something else is lost. Families with less money are priced out by the costs of new construction, and so are the innovative new ventures that cities thrive on. As Jacobs puts it, “Old ideas can sometimes use new buildings. New ideas must use old buildings.” She believed that, as long as zoning laws are flexible or at least generously enforced, any urban neighborhood could naturally evolve into a vibrant, historically diverse district.

Can this kind of historical “character” be measured somehow? Today we have tools like Walk Score that measure the concentration of different amenities around a home. Prospective buyers or renters can use it to help them decide whether the home fits their lifestyle or not. And the online tool Abogo gives us some idea of how much transportation might cost while living at a given location. Wouldn’t it be cool if we could do the same thing for the historic diversity of the area around the home?

I decided to use my own home in Charlottesville, Va., as an experiment. First, I dug up the year that each building in my neighborhood was built, using the city’s tax assessment records, which should be publically available in your own community as well. The numbers gave me the map above.

Then I drew a circle with a quarter-mile radius around my house — basically encompassing anything I can walk to — and looked at all of the buildings that fell within it. There are 423 of them, and the chart below shows when they were built.

We see a nice balance of older working-class bungalows, lots of standard ranches, and even a smattering of funky new modernist homes here and there. There’s a quiet period between the ’60s and the ’90s, when builders bypassed our neighborhood for the greener pastures beyond. But in the last decade, newer infill homes have broadened the range of styles and quality available. This wide range of housing ages translates to a wide range of prices, which means a diverse cross-section of people living together. Of course, a lot of these features are what drew us to live here in the first place.

To come up with a meaningful way to compare different neighborhoods, we’d need a score for this kind of historic diversity. The easiest way to do this is to just take the standard deviation of the years each structure was built. For the area encircling our home, this comes out to 24.7. That’s our score. I see no reason why this couldn’t be plugged into a database and computed for every home in the United States. Then I’d have some frame of reference for what my number actually means.

Sure, it’s not the same as walking around the block and observing how the pieces of the built environment have grown up together over time, but it would put an objective stamp on an area that might help us explore all sorts of interesting correlations. Do historically diverse neighborhoods have more resilient property values? Are they more walkable? Are they also economically or racially diverse? Jane Jacobs thought so (and so do I), but it would be nice to be able to show it with numbers.

Designs that are easiest for the disabled to navigate can benefit all users.Illustration from Inclusive Design: A Pattern Book

I wouldn’t normally be this OCD about stroller convenience, but reading Inclusive Design: A Pattern Book is reorienting my perspective. The good folks at the Center of Inclusive Design and Environmental Access have just published, from what I can tell, the first guide to marrying sustainable urbanism to accessible design. Although my daughter can easily be carried over these obstacles, any disabled person in a wheelchair cannot. This trip would not be possible, nor would buying or renting my home without some serious modifications.

This matters to anyone hoping to encourage authentic urban living options — for a few reasons. We’re living longer and we’ll probably be frail for those last few years. More and more elderly Americans are looking for ways to avoid high-cost institutional living by staying independent in the homes they know. Remember, the baby boomers loom on the edge of retirement like an approaching tidal wave. They’ll want somewhere suitable to age in place.

Most observers believe the movement toward walkable, urban neighborhoods is being driven by two demographics. There’s the younger post-college set for whom the love affair with automobile has fizzled (and they’re not returning the phone calls). Let’s be honest. Many of us who chatter away on the internet have this group in mind, because many of us are this group.

But the other group carries arguably more force to the market. Their kids have left home, and the square footage they once coveted in a house is now just more to clean. The expansive lawn is just more to mow. Eventually, community and security begin to trump privacy. It’s no coincidence that the AARP is one of the strongest proponents for livable communities at all levels of policy and design. These retirees will need accessibility.

But the point of the book isn’t really to convince you of this. It’s to show builders and planners, or really anyone who’ll listen, how to design the urban environment to include those with special needs. The authors make the case that, as long accessibility is in mind from the outset, there’s very little extra cost or aesthetic sacrifice to it. For example, they show that purchasing a 36-inch door from a wholesaler costs only a few dollars more than a 32-inch one, regardless of the regional market. Most of us wouldn’t notice the difference, but a standard wheelchair cannot pass through the 32-inch door. There are dozens of simple design decisions that may be overlooked.

There’s a heavy emphasis on building right the first time. Those awkward ramps up the front steps you sometimes see get no accolades from the authors. Retrofits like these are Band-Aids that only serve to marginalize the homeowner. The better way is to grade up to a zero-step entrance before the house is ever built. Fair enough, but those of us who can only work with the template we’ve been given can feel a little left out while reading. The section on neighborhood design includes great advice on connecting blocks to allow easy walking routes, but it’s addressed to those “laying out a new neighborhood.” These are the days of adapting and transforming what we already have. Sequel, maybe?

Back to my daughter in her stroller. The point driven home by Inclusive Design is that placemaking for those with the greatest needs will benefit all of us. The bollards guarding the sidewalk from vehicular traffic protect the blind man and the distracted pedestrian on his cell phone alike. A graded entry up to a home is handy when you’re pushing a couch on a dolly. So are wider doorways. And, sure, I’ll survive lifting the wobbly stroller wheels off the ground, but I’d take the nicely graded path any day.

Grist’s Feeding the City series began by exploring how the history of urban agriculture should inspire its future, then went on to spotlight the farms, governments, businesses, and people who’re skillfully planting new ideas alongside the old. Here, as the series draws to a close, planner Daniel Nairn untangles how smart growth can include city farming.

The ’garden block’ concept embeds pockets of food growing within the urban fabric.Rendering: Daniel Nairn

Urban agriculture is a movement in transition. And it’s happening fast. Just a couple of years ago, we started hearing about Detroit’s guerrilla gardeners, reclaiming patches of vacant land in the name of fresh food, and now some of those same parcels are being assembled into large, commercially viable farming ventures. (See “Three projects that are watering Detroit’s food deserts.”) We’ve long had community gardens enriching neighborhoods, and now some architects and developers have their sights on large-scale developments centered on food production. On the zoning front, the major challenge was once just obtaining the legal right to grow vegetables and raise a chicken or two in your yard. Now some planners are pondering whole new agricultural districts within city limits.

Whenever any movement ratchets up to the next level, there’s a chance to take the message mainstream and get some powerful results. Big players who were cautiously watching the trends are now willing to put money or political capital on the table. There’s nothing wrong with seizing the moment while enthusiasm is high, but just as important is some careful and sober reflection on where it is all going. Land use is an incredibly complex arena, and no one answer is ever right in every situation. There are pitfalls to watch out for.

Strange fruit choices

Kaid Benfield, director of Smart Growth for the Natural Resources Defense Council, has long praised compact and vibrant urban neighborhoods as an antidote for chewing up more farmland on the exurban fringes. Thinking regionally, it just makes more sense to concentrate the dense network of human connections closer to the center of metro areas and to leave the natural systems in place at the edges. Benfield doesn’t hesitate to ask difficult questions about the experiments in agricultural urbanism that reverse this order.   

He points to two examples on opposite sides of the spectrum — a close-in site perfectly suited for the intensive uses being proposed for agriculture, and a farmland site on the far reaches of a metropolitan area being proposed for a village — all in the name of marrying the urban and the rural.

He’s blogged about the first case, a plot of land near Logan Square in the heart of Chicago. Despite its pedestrian-oriented location on a major street, mere hundreds of feet from a Chicago El transit stop, some advocates would like to use the recently cleared land for an orchard.

Making the most of the transit system and the dense patchwork of mixed uses along the street means condensing as much human activity as possible into one place. Benfield rightly asks whether an urban farm makes the most sense in this context. “I love the idea of the orchard in concept, but its proponents may be seizing the most opportunistic space rather than the best one for their project,” he says. “My instinct is that the residents of Chicago should have their orchard, but not on a potentially busy commercial strip so close to a transit station.”

The other case is Southlands, a proposed subdivision that would add thousands of homes into an existing agricultural landscape at the very outer fringes of Vancouver’s metro area. On paper, it’s an impressively designed village nestled into farmland and open space, with the laudable goal of enhancing residents’ recognition of and participation in growing their own food. This is probably why the jury at the Congress for New Urbanism selected it for a 2010 Charter Award.

But Benfield is concerned with how this would all play out. The proposed gross density is so low that residents will inevitably fire up their car engines for the 17-mile trip into Vancouver. Extending all of the water and sewer pipes to a previously undeveloped site is also inefficient. Once the land is fragmented, it’s harder for farmers to use it effectively.

Finally, development begets development. What happens when residents start asking for a shopping center or an office park nearby? Benfield wonders whether the project, however attractively packaged, could simply be “agri-spawl.”

It’s worth noting that the Vancouver Metro government has designated the Southlands site as a Green Zone, set aside exclusively for agriculture and open space. It’s part of an urban growth boundary that has been doggedly defended since the early ’90s. There’s no getting around the fact that the development would involve a rewrite of the earlier sustainability goals.

A marriage of equals

It looks like one of the main take-aways from the Congress for the New Urbanism 18 conference is something being labeled “agrarian urbanism.” Fast Company is calling it the “new new urbanism” and Treehugger has described the notion as the next phase in the evolution of this 30-year old movement. New Urbanism leader Andrés Duany, in particular, has been pushing pretty hard in this direction for the last couple of years.

Briefly, the idea is that walkable neighborhoods could be intentionally structured so that food production is integrated into the physical form and the lifestyle of the inhabitants. In other words, it’s a synthesis between urban and rural.

Instead of embedding hamlets within a rural landscape, the garden block embeds pockets of agriculture within the urban landscape. It is not a stand-alone community but just another gene sequence to be spliced into the DNA of existing inner suburbs and cities.

Of course, this new new urbanism is really no newer than the old new urbanism was (but that’s fine). One of the primary motivations behind Ebenezer Howard’s Garden Cities of To-morrow concept was to connect working-class households with a viable food supply to relieve some of their financial stress. He landed on the number of 12 dwelling units per acre (DUA) as the magic density for self-sufficiency with affordability, and he worked out a form of common land ownership to help it along. Urban planner Christopher Alexander thought that something more like a tenth of an acre was necessary to supply vegetables to a family of four. He had plenty of practical, timeless advice for arranging an urban living space accordingly. More recently, some architects have been using the word “rurbalization” to describe this sort of synthesis. Having recently passed through the grad-school circuit myself, I can attest to a strong interest in food systems among new graduates.

I think these are good trends. Local food systems should inform urban design and vice versa, but I’m not sure the new developments being modeled have been able to find this synthesis without swallowing one side with the other — specifically, subsuming the urbanism into the bucolic landscape. This seems to be the case with Southlands in British Columbia and Serenbe in the exurbs of Atlanta. Kaid Benfield has this to say about these “farming is the new golf” developments,

“In theory, these “new towns” are great — self-contained entities providing walkability, efficiency, and all the services of a community within the development. So, their proponents (nearly all of whom profit from them, one way or another) claim, it is a good thing to build them almost anywhere. In practice, though, the nearby once-remote locations soon become filled with sprawl, in no small part because of the initial development, and the theoretical self-contained transportation efficiency never comes. They become commuter suburbs, just with a more appealing internal design than that of their neighbors.”

So can this vision work? Or is building agrarian urbanism like serving a glass of hot cold water? I’d like to play with this a little and consider what it would look like if we followed Duany’s vision but flipped it on its head. Instead of embedding hamlets within a rural landscape, the garden block embeds pockets of agriculture within the urban landscape. It is not a stand-alone community but just another gene sequence to be spliced into the DNA of existing inner suburbs and cities.

Start with the standard grid. It can be found all over North America, but the following sketch is based on the 340-by-340-foot block in the Fan neighborhood of Richmond. Cobble together property ownership for the whole block into something like a community land trust. Households would own their home individually but share ownership of the land with the other 38, in this case, units on the block. Certain commitments to planting and maintaining the garden, either personally or through payment, would be built into an HOA contract.

(Daniel Nairn renderings)

The exterior of the block functions as in any other urban area. The public streets are activated by the fronts of the buildings and streetscape features, and the full range of transportation access to the rest of the city is available. The interior, on the other hand, is devoted to the more constrained social scale of the block community, and the structures serve as a wall protecting this garden area. Enclosure is necessary to provide a degree of privacy, to protect produce from theft and vandalism, and to keep animals from wandering.

By the numbers, this block allows a density of 15 DUA while keeping 28 percent of all land for growing produce. This is not food self-sufficiency, but I’m personally not too worried about these kinds of absolutes.

Here are some of the pieces: