An innovative street grid proposal
Of all the changes in the built environment in the 20th Century, none had more impact than abandoning the street grid—which occurred in the US around 1950.
That one change did more to eliminate walkability long-term, and the effects on public health and safety are dramatic. The street network change triples road fatalities, according to a study of 24 California cities—half of which were laid out mostly before 1950, and the other half mostly after. A second study of these same cities correlated the post-1950 networks with higher obesity, heart disease, and high blood pressure.
The studies may underestimate the impact of the street network shift since all of the cities have some sprawl. Jeff Speck reports that if you compare traditional cities like New York or San Francisco to a place that is nearly 100 percent sprawl (Hillsboro County, FL), the sprawl has 17 times higher road fatalities.
As of 2020 there were hopeful signs that US street grids were coming back due to infill development and New Urbanism, according to USC researcher Geoff Boeing. But I fear that the population shifts this decade signal a return to development on the suburban fringe, where dendritic street networks still dominate.
We need more innovative street networks that apply to contemporary conditions and economies. In that interest, I highlight the work of Korkut Onaran and Andres Duany, detailed in Onaran’s 2022 book Urbanism for a Difficult Future. The book describes the Adaptation Village, a response to climate change, which offers a new twist on connected street networks.
Adaptation Villages, which accommodate 5,000 people, are designed around self-reliance, and that means efficient, low-cost, fine-grained walkability. Only the primary thoroughfares heading in and out of the village are designed as typical streets with sidewalks—and these with relatively modest curb-to-curb widths of 32 to 44 feet. “No vehicle would need to travel these streets at more than 25 miles per hour speed,” Onaran writes. Streets would have all of the commercial frontages in the village center and include on-street parking.
The bulk of the village thoroughfares would be shared-use mews streets, in which people walk, bike, and drive (slowly) in the same right of way. The “primary mews” would have a 60-foot right of way, with street trees and parking in the center. The secondary mews would be half that size, detailed essentially as lanes. All mews, primary and secondary, would have a minimum of “20 foot clear” to meet codes for emergency response apparatus.
“The design of this network follows two principles,” Onaran explains. “The first is slow speed; there is no need for high-speed roads in a settlement that operates primarily within a walking shed. The second is sharing; pedestrians may easily share these thoroughfares with low-speed motorized and non-motorized vehicles, with no separation or sidewalks. There are sidewalks only on regular streets, which are limited to those leading to the village center and looping around the central greens.”
The blocks, which are squarish in shape, are large and accessed only by pedestrian paths in the interior. The block shares a center-block open space. The blocks each have eight “compounds,” or groupings of houses, which allow for extended families or other units of households. Adaptation Villages have a social structure designed to make them more resilient in a “difficult future” of climate change and unreliable national energy systems. But you don’t have to share that future vision to see why this block and street structure would be effective regarding costs, health, and quality of life.
This system of paths, mews, and a few full-fledged streets delivers very efficient walkability. At a time when housing costs are high, and the supply of walkable neighborhoods is low, the Adaptation Village grid is a proposal worth considering. There's much more to the Adaptation Village concept and Urbanism for a Difficult Future. If you want to take a deeper dive, see the On the Park Bench webinar from November, 2022.
