The Urban Transect
A diagram based on Alexander von Humbolt's transect theory that everything has its place in nature. Considering the transect theory, fish are not likely to live in the forest, just as pristine wilderness is not likely to be found in the urban core of large cities. Exceptions, like Central Park can be made, of course.
Urban Design Derived from Nature
DPZ's plans are often accompanied by Form-Based codes keyed to a Transect, an ordering device adapted by DPZ from the world of science. A geographical cross-section of a selected environment, that helps identify the habitats in which certain plants and animals thrive, the Transect has existed as an analytical tool used by scientists, such as Alexander von Humbolt, as early as the 18th century. As human beings also thrive in different habitats (some would never choose to live in the urban core, and some would wither in a rural place), the Transect can be applied to urban design.
DPZ's Transect is a master planning tool that guides the placement and form of buildings and landscape, allocates uses and densities, and appropriately details civic spaces, including the selection of tree types and lighting poles for thoroughfares. A model Transect, depicted below, is included in the SmartCode. For simplicity is it divided into six zones, nicknamed "T-Zones", which increase in intensity of development towards the higher T-zones (T5 and T6) and decrease to the agrarian and untouched natural conditions (T2 and T1). Many human settlements are organized this way, in which the walkable neighborhood with a center and an edge, provides this natural gradient. This can be seen in traditional towns around the world, from those recorded in the ancient scrolls of China to medieval english villages to pre-war american towns.
The Urban Transect guides the development intensity from nature (T1) to the most urban (T6).
More About the Transect
The following is an updated excerpt from a 2000 Article in the Fordham Law Journal by Andrés Duany and Emily Talen - Making the Good Easy: The SmartCode Alternative
Transect is a geographic cross section of a region used to reveal a sequence of environments. For human occupied environments, this cross-section can be used to identify a set of habitats that vary by their level and intensity of urban character - a continuum that ranges from rural to urban. This range of environments is the basis for organizing the components of the built world: building, lot, land use, street, and all of the other physical elements of the human habitat. In each human habitat along the rural to urban Transect, “immersive” environments are created - places that have an integrity and coherence about them because of their particular combinations of elements.
The Transect works by allocating elements that make up the human habitat to appropriate geographic locations. For example, human habitats that are rural might consist of wide streets and open swales. Human habitats that are more urban will likely consist of multi-story buildings and public squares. Accordingly, wide streets and open swales should be allocated to more rural zones whereas multi-story buildings and public squares should be allocated to more urban zones. This proper geographic “appropriation” serves to better integrate natural and urban systems because one is defined in tandem with the other. Conventional zones ignore this interrelationship.
The Transect seeks to rectify the inappropriate intermixing of rural and urban elements known as sprawl. No desire for a particular type of development is categorically “wrong;” it is just in the wrong Transect location. The transect eliminates the “urbanizing of the rural” - office towers in otherwise pristine environments - or equally damaging, the “ruralizing of the urban” - undefined, vacant open space in the urban core. The prescribed urban pattern is therefore based on, theoretically, finding the proper balance between natural and human-made environments along the rural-to-urban Transect.
In nature, the sequence of habitats is continuous, but in human environments the rural-to-urban continuum must initially be segmented into discrete categories. This is dictated by the requirement that human habitats fit within the language of our current approach to land regulation - zoning. In other words, codes of perfectly familiar formats can be written based on Transect Zones. To explain this more exactly, a diagram of the nomenclature of the Transect is presented in Figure 1.
The Segmentation of the Transect continuum is accomplished by dividing it into six different Transect Zones: Rural Preserve (T1), Rural Reserves (T2), Sub-Urban (T3), General Urban (T4), Urban Center (T5), and Urban Core (T6). While these categories work well, it is important to note that other immersive categories have been proposed that somewhat resemble the zones discussed here. Brower’s typology of neighborhoods is one example.
The Transect approach is essentially a matter of finding an appropriate spatial allocation of the elements that make up the human habitat. Rural elements should be located in rural locations, while urban elements should be located in more urban locations - not unlike natural ecological systems where plant and animal species coexist within habitats that best support them. In the Transect system, urban development is distributed so that it strengthens rather than stresses the integrity of each immersive environment. The Transect approach also controls the geographic extent of zones, disallowing the creation of large monocultures of any one particular type of Transect Zone.
The Transect should also be viewed as a way of applying good urban principles to a range of human habitats. The idea that human environments should be pedestrian-oriented, divers and public is intrinsic to each type of environment along the Transect. The Transec approach also factors in the element of time, as a Transect Zone can change to another type of immersive environment (usually one of higher urban intensity - though at the current moment we are likely to be seeing mostly devolution of sprawl, returning to a more rural character and only occasionally intensifying where appropriate).