Living Urbanism

Living Urbanism and Sustainable Commerce by russellpreston
December 8, 2010, 11:10 AM
Filed under: Commerce & Retail, Volume 003 | Tags: , , , ,

By Seth Harry, AIA, CNU – October 6, 2010

Historical Background

Emerging coincidently with the advent of agriculture, urbanism—a tool for maximizing the value of limited resources through spatial efficiencies and the effective leveraging of collective skills— is one of mankind’s greatest and most enduring inventions.  The surplus production and storage of food that agriculture provided encouraged stability and allowed for both specialization and the systematic exchange of goods and services on a localized basis.  This, in turn, led to the creation of a rational framework of land division and individual access based upon formal geometric relationships that have proven remarkably consistent across both geographical and generational divides:  The long-gone residents of Pompeii—the Roman-era town frozen in time by volcanic eruption 2,000 years ago—would have felt right at home as contemporary inhabitants of Antigua de Guatemala, a vibrant, colonial-era New World capitol, and vice-versa.

This continuity of form and function over the centuries is no accident.  Specialization and the division of labor encouraged the development of more complex and robust systems from which modern civilization emerged, including efficient social and production networks optimized around the unique features and indigenous resources found within the regions in which these settlements formed.  As a complex dynamic system for human habitation, urbanism shares many attributes and characteristics with natural ecosystems in the sense that the competitive checks and balances within the collective enterprise, by nature, work toward maximizing efficiency and resource utilization over time. This system is enhanced and facilitated through the physical characteristics of the built environment itself.  The result is a sustainable model in which the value and usefulness of the output routinely surpasses that of the collective inputs, such that a progressively higher quality of life is consistently realized over time.

Once the basic framework of urban form was established, the competing dictates of access, capacity, and mobility quickly generated the basic format that emerged— a contiguous network of small-scale blocks and streets.  The desire for frontage (width), balanced against the need for capacity (depth), and the shared interests of collective mobility tempered both, keeping block dimensions to a minimum in size, facilitating movement across the fabric.  This archetypal form has remained relatively unchanged over the millennia that followed, and continues to prove its relevance to this day.

Over time, these individual settlements typically coalesced within a regional context into semi-autonomous economic constructs, which translated agrarian, craft, and cultural traditions into a coherent set of principles and practices through which the local trade in goods and services could be effectively managed over time.  Prior to the industrial revolution, this approach generally encouraged a sense of stewardship toward the land which promoted long-term sustainability through the carefully managed use of local resources, and shared assets, in a largely agricultural-based economy.

As these regions matured, and the scale and nature of local production increased to encompass a broader range of consumer goods, these products were typically distributed and marketed within the community through an efficient network of small-scale merchants and entrepreneurs relying primarily on locally sourced goods for inventory, and tied closely to the physical and spatial structure of the settlements they served.

This model was not only inherently efficient, it also internalized local consumer spending in a systemic fashion which recycled the value of those purchases many times over throughout the local economy.  This, in turn, helped ensure a stable and prosperous community, supported by a largely self-sustaining economic system that could operate independently of extra-regional economic trends and developments.

The Modern Era

Beginning in the early Twentieth century, this systemic model of localized production and consumption began to change.  Innovations in mechanized transport expanded the reach of urban cores, as the promise of personal mobility on a mass scale precipitated the first substantive break from the established geometric and spatial patterns of the previous four thousand years.  As documented in the analysis of neighborhood street patterns, by Michael Southworth and Peter Owens, the enhanced mobility provided by the automobile began to subtly change settlement patterns and their associated road networks, over the course of the 20th century.  Their diagram shows a progression of street network types from the traditional “gridiron” of 1900, through “fragmented parallel” circa 1950, proceeding through “warped parallel” (c1960), “loops and lollipops” (c. 1970), and finally, “lollipops on a stick”  (c. 1980), the latter representing a 70% reduction in connectivity, from the original grid configuration.  As it became both feasible, and  more marketable, to segregate uses and residential product types from one another into physically discrete pods, or sub-groupings, this trend toward income stratification and spatial isolation was further exacerbated.

Characterized by ad-hoc, “leap-frog” development, these new large-scale subdivisions and so-called planned communities fully exploited these newly articulated class distinctions, and became the dominant new model of growth in the last half of the last century, the cul-de-sac its increasingly ubiquitous symbol.

The street patterns described in Southworth’s and Owens’ diagram, which were typically overlaid directly upon the existing rural road networks of the immediate post-war era, resulted in a steady decrease in the level of overall connectivity at the regional scale.  This trend, combined with the lower densities of suburbia, generally meant that trips between home, work, and school required a greater number of individual vehicle trips over ever increasing distances.  This, in turn, had its own implications—a decrease in overall economic productivity, greater levels of environmental degradation associated with increased vehicle miles traveled (VMT) and corresponding greenhouse gas emissions, an increase in impervious areas and related loss of habitat, productive farmland and reduced water and air quality—all related to accommodating the automobile both on the road and at rest.

The evolution of Omaha's street grid shows an increasing reliance on a limited network of over-scaled arterials, which results in a substantial increase in the amount of vehicle miles traveled and an overall loss of retail diversity.

Over time, this transformation from the fine-grained street networks of our traditional urban cores, to an ever more dendritic street system, spreading relentlessly outward with new suburban development, meant that increasing numbers of car trips were traversing a less and less well-connected arterial network (see illustration # 1).  The net result was that everyone residing within a particular suburban trip-shed were collectively delivered—with unfailing predictability—to the same major arterial interchange as everyone else in that trip shed, just as surely as a squirrel working his way down the branches of a tree would arrive at the same place, on the same trunk, as any other squirrel starting from a completely different branch on that tree would.

The implications of this phenomenon became quickly apparent to the burgeoning suburban retail industry, which perceived itself as distinct from the “old fashioned” urban retailers. It further segregated by creating its very own trade associations (the International Council of Shopping Centers); for the first time in the history of human settlements, the merchant was no longer obligated to deliver his wares to the consumer. Rather, the consumer was obligated to drive past the merchant, and the industry responded by building ever bigger boxes to dominate and control this new domain.

The underlying dynamics of how and why this system worked so well can be explained by two basic concepts.  The first is Casey Wahthorne’s “Traffic Route Equation,” which shows the exponential relationship between the number of intersections in a street network and the possible number of routes which can be taken between two points within that network.  A traditional urban “grid” as illustrated in the first diagram of the Comparative Analysis of Neighborhood Street Patterns, above, contains a continuous fabric of interconnected streets.  In that context, even two relatively close by destinations (say, within an 8 X 8 grid – much smaller than a typical neighborhood) yields as many as 12,870 possible ways in which one can choose travel between Point A and Point B.

That means that in a traditional grid system, the distribution and nature of retail offerings are effectively moderated by the merchant’s proximity to, and the density of, its immediate consumer market.  In suburbia, however, everyone is more-or-less required to traverse the same piece of asphalt over and over again, meaning that the size of the box is essentially determined solely by the size of the road in front of it, regardless of context.

This relates directly to the second concept, Riley’s Law of Retail Gravitation, which  says that “all things being equal, people will shop at the largest concentration of retail most easily reached, in direct proportion to the relative size of the retail centers being compared.”  While this theorem was originally conceived to define the relative break point in the respective trade areas between two competing urban centers, it also works wonderfully to describe how retail markets work in the contemporary equivalent of a featureless, generic context, i.e., suburbia.

Given these two interrelated concepts, the most consistently effective strategy for suburban retailers to control market share was to build the biggest box supportable, based upon its associated dendritic market-shed, irrespective of the immediate context. The result is an ironic “suburban conundrum” whereby road and box sizes typically increase in an inverse relationship to the decrease in connectivity and gross density.

And because this transition happened not only gradually over time, but over distance (see previous illustration), each subsequently larger generation of retail development, consistent with Reilley’s law, was able to usurp a portion of the previous generation’s consumer base.  The latest generation of suburban retail thereby cannibalizes market share on a kind of “trickle down” basis, as each preceding generation did, all the way back to the earliest vestige of extant urban fabric in the chain.  And as misguided changes in land-use and zoning regulations intended to “suburbanize” existing urban centers further corrode existing fabric, the amount of viable, extant urbanism able to withstand these competitive threats, diminishes with each passing year.


An increasingly over-scaled street and block network, abutted by a disconnected, dendritic street pattern of residential enclaves forces inhabitants to run the gauntlet of over-scaled retail boxes—sized in accordance with Reilly's Law of Retail Gravity—on their daily commutes.

Remediation – the Coming Restorative Age

One way to “prove” an empirically-based hypothesis is that if a certain casual relationship is said to produce one set of results, presumably the elimination of that casual factor should reverse the outcome.  If the basic premise is that intrinsic features of suburbia–segregated, low density, single-use, poorly connected development–enabled and encouraged a fundamental change in the nature of goods production and distribution on a global basis, than the opposite must also be true.

The generic nature of suburbia places an emphasis on quantity over quality and price over value, such that the nature in which the consumer engages the producer is less than merely incidental to the transaction.  The advent of industrial farming, and global production and distribution networks means that what goes on “behind the curtain” in delivering a particular product to the shelf of the local big box retailer is of little consequence to the prospective buyer. Their only concern is that it is cheaper than it was yesterday, and cheaper still than the day before that. The larger systemic consequences of everything from the near collapse of global environments and ecosystems, to the global economic crisis and record unemployment, could be legitimately related to the cumulative long-term effects of what may have at first appeared to be an innocent, and well-intended objective, providing the consumer with the most product at the least price.  Unfortunately, the real long-term cost of those goods may still be coming due.

However, if, in fact, these larger systemic crises may have had — at least in part — their genesis in the unintended consequences of our embrace of suburban land-use and transportation policies, then it is reasonable to assume that the reverse might be true.  As the mega-retailers who honed their competitive models in the wide-open landscapes of suburbia begin their move into the final market frontier in their ceaseless quest for global domination—into our urban centers—the reapplication of the moderating forces whose absence encouraged and enabled their quantum leaps in scale should begin to shrink their size and trade area.   This is exactly what has been happening.  Many of the major big box retailers including Walmart, Target, and Meijer, have recently announced plans to launch new, smaller formats, specifically in anticipation of pursuing urban markets.  This trend has been further hastened by new players like Tesco, a UK-based grocer that has long used multiple formats tailored to fit a spectrum of urban/suburban contexts, has recently introduced its 15,000 sq. ft. Fresh and Easy grocery concept in the US. This is a clear effort to preemptively deny market share to established big-box players like Walmart, by going into urban markets which cannot easily accommodate Walmart’s conventional suburban stores.

This small-scale mixed-use building, and its ground floor commercial tenant are typical of the independent business found in the neighborhoods surrounding downtown Grand Rapids.

Certainly, in some places, these suburban retailers are building full-size stores, but that shouldn’t necessarily be seen as a contradiction to this inverse proof. They are typically only able to do this where the localized density or the presence of transit are effectively compelling the retail format to match the local market potential, in the same way that large department stores were traditionally part of the downtown landscape.  However, in true urbanism, unlike in suburbia, Hawthorne’s Route Equation helps ensure that no single retailer can dominate the market purely on the basis of overwhelming scale.  In fact, local and independent retail often thrive alongside national and multinational chains in healthy urban fabric.


The small-scale mixed-use building type and uses shown in Illustration 3A contrasts dramatically with the large format, generic retail boxes, which are susceptible to loss of future market share to even bigger competitors, situated on even bigger roads.

In the absence of “downtown” urban densities, the moderating effects of urban form will still generate a retail culture distinct from suburbia’s.  The accompanying illustrations from Grand Rapids, Michigan, show small-scale, independent retail lining the small arterials within the city’s pre-war residential fabric, an area characterized by a contiguous network of fine grained streets and blocks.  This stands in stark contrast with the large scale block and arterial network only a short distance away, in the southeastern reaches of the city.  Certainly, Grand Rapids is a small enough market, both physically and demographically, that these suburban retail concentrations have had a notably deleterious effect on the overall regional retail landscape. But where these urban characteristics are still viably extant at the neighborhood scale, local, small-scale retail remains healthy and vibrant (see illustrations #2,#3).

It would be arbitrary and unreasonable to demand an urban retail format to compete directly in an otherwise suburban market context without some type of mediation that acknowledges the distinctions in how both formats have optimized around their respective environments.  However, in consciously planning a long-term transition from suburban to urban form through the deliberate application of a transformative regulatory mechanism, such as a comprehensive form-based code, it is critically important to establish a credible baseline frame of reference. This should be based upon a defensible conceptual model that accurately represents the fundamental way in which urban markets work, so that it may be effectively calibrated to existing local conditions.


This diagram, part of the SmartCode Module on Sustainable Commerce, provides an ideal schematic illustration of a coherent urban structure which the distribution of retail goods and services are balanced, relative to demand, across the full spectrum of urban contexts (Transect zones).

Restoring Diversity and Establishing Local Markets

One such tool for establishing this credible reference and for facilitating local calibration of an existing commercial context is the SmartCode Module for Sustainable Commerce.  The triangle diagram contained within the module (illustration #4), shows how an idealized retail ecosystem, efficiently allocated within a coherent urban fabric, evolves over time through successional levels of scale and complexity that correspond perfectly to its associated urbanism.

In an attempt to mediate suburban retail trends, and to create a more vibrant and walkable context to our suburban communities, a number of strategies have been explored and developed. These illustrations demonstrate how a typical single-use suburban commercial node, located at the intersection of two large arterial corridors, can be redeveloped as a higher-density, mixed-use place-based commercial center.

Using a template like this can be helpful in crafting non-arbitrary regulatory entitlements that incentivize a design-based approach to remediating suburban markets, allowing them to function more like traditional urban consumer markets over time.  The benefits of this approach is in allowing a more diverse, and hence, more resilient and flexible commercial ecosystem to emerge; an ecosystem that returns more of the resident consumer expenditures back into the local economy, encouraging healthier consumer choice in terms of locally-sourced food and produce, supporting local agriculture, CSAs, and farm-to-table programs.  This has the added benefit of making agriculture a more competitive economic alternative to sprawl, while encouraging smaller scale, non-industrial farms and farming practices, employing more sustainable models of high-yield cultivation (permaculture), and providing additional incentives to build more compactly, preserving open space, and reducing sprawl-related environmental impacts. Ultimately, this model provides a backbone impetus to a range of more sustainable land-use and transportation practices, including a broad spectrum transportation system.

Examples of remedial applications in archetypal suburban settings including the introduction of transit and infill residential into dense commercial districts, and the redevelopment of suburban corridors and nodes (illustrations #5,#6, #7). These can be strategically planned to provide a realistic, market-driven implementation that builds cumulatively toward ever higher levels of performance and efficiency. Based upon urban principles, the SmartCode Retail Module for Sustainable Commerce provides a legally defensible basis for instituting appropriate regulatory policies and infrastructure investments to reshape our communities: from an unsustainable automobile-reliant urban form to a flexible and robust Living Urbanism, capable of continual reinvention over time while rewarding true entrepreneurial initiatives that benefit the individual and the entire community.

Against this backdrop it is not a coincidence that Detroit, a failed symbol of automobile-based economies, and one of the first cities to embrace it as a planning paradigm, has reemerged as a leader in local entrepreneurship and self-sufficiency.  As the region continues its efforts to reinvent itself, it is finding that going back to basics and the intrinsic, underlying attributes of place, have reenergized the true capitalist power of urbanism. Ultimately, Fair Trade, record high unemployment, and a more liberalized currency policy in China could be the catalyst for a lasting and sustained recovery.   This is not about looking backward, but about rebuilding our local economies in a fundamental way that will allow us to refocus our efforts on competing effectively in the global economy.

– – –

1 A dendritic street pattern resembles a tree-like structure, with a large trunk and smaller branches all connecting to the main trunk. The term borrows from the physiological term dendrite, which refers to the branching structure at the end of nerve cells.

2 Riley’s Law of Retail Gravitation here is loosely translated to make it more relevant to contemporary transportation planning principles. It was originally postulated in the 1930’s to describe the relative market draw, between two distinct consumer markets in an otherwise generic regional context. In economicsReilly’s law of retail gravitation states that larger cities will have larger spheres of influence than smaller ones, meaning people travel further to reach a larger city.

The law presumes the geography of the area is flat without any rivers, roads or mountains to alter a consumer’s decision of where to travel to buy goods. It also assumes consumers are indifferent between the actual cities.

The law was developed by William J. Reilly in 1931.

A plain English paraphrase would be that the balance or Break Point (BP) is equal to the Distance (d) between two places, divided by the following: Unity or Total (1) plus the Square Root of the size of Place One (p1) divided by the size of Place Two (p2). d is distance and p1 and p2 are the sizes of the places between which the distance exists; the answer will give the distance from p2, also called a break-point. What is the break-point? As an example: after leaving a store you remember something that you wanted to buy; it just so happens that you are headed towards an alternative store b. The break-point can be thought of as the point after which you would travel towards store b instead of store a because of its notional “gravity”. This would happen sooner, for example, if store b is an equivalent store but with greater square footage, suggesting that you are more likely to go to store b for greater available utility. This notional gravity can be influenced by a number of things, but square footage is simple and effective.

3 A broad spectrum transportation system uses a range of mobility and transit options specifically tailored to settlement patterns and place-types to efficiently accommodate a wide range of lifestyle choices, while providing convenient access to daily needs and other consumer goods within a compact, walking neighborhood structure.


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