by Stephen Kieran, FAIA and James Timberlake, FAIA
As a nation, we have long preferred to live in the suburbs, a way of life sustained by the regional highway system. Increasingly, we are moving our businesses to new, car-oriented cities that are springing up all over the country. These "perimeter centers" are not defined by the edge of a host city, but rather are ordered by the highway interchange. Perimeter centers cannot be understood in terms of conventional building-to-building or building-to-road relationships, but as abstract circuitries of roadway, each isolated from the next by an insulating "green veil" connecting unseen structures in gardens of commerce and living.
Perimeter centers and their emerging building typologies have been unfairly criticized for deficiencies in comparison to traditional urban forms. They represent a morphological change as different from the Strip as the Strip was from Main Street and the conventional urban grid. In 1968, Robert Venturi, Denise Scott Brown, and Steven Izenour analyzed the Las Vegas Strip as the dematerialization of Main Street's slow-moving spatial enclosure into a mid-speed array of information. The Strip, in turn, has been further dematerialized by the interstate highway network into an aspatial, but ordered, contemporary City in the Garden.
It is interstate highways that have provided the mechanism on a regional scale for the reclamation of paradise in the extended garden of America. This high-speed system and accompanying development cannot be comprehended through traditional types of urban analysis. Search the figure-ground topographies of King of Prussia, Pennsylvania; Perimeter Center, Georgia; Tysons Corner, Virginia; or Irvine, California, and few, if any, spaces attain focal status as "rooms." Like a broken kaleidoscope in which the elements fail to coalesce into recognizable patterns, buildings and asphalt appear like isolated, internalized fragments, neither figure nor ground.
Perimeter Center icon
The Nolli plan of Rome has become the architect's icon of the traditional city, and the Strip as information overlay has assumed a comparable role in our understanding of the mid-speed automotive world. What is the graphic icon of the high-speed perimeter center? Neither figural space nor information display, the icon of this new urban form most closely resembles electronic or hydraulic circuitry, with each line representing an individual automotive passage, each overlay an interchange, and each node in the diagram corresponding to a destination. In short, the only self-contained spaces in the new perimeter center are internalized and privatized automobile and building interiors; everything beyond these realms is simply asphalt circuitry overlaying a garden. Nonetheless, this circuitry, and the garden it occupies, can sustain analysis as a purposeful -- even desirable -- vernacular form. Further, and perhaps more disturbing to architects, it is our contention that architecture is rendered nearly meaningless in this new tapis vert.
Prior to the advent of the interstate highway system, infrastructure and buildings normally shadowed each other, with the road, be it Main Street or the Strip, providing the economic and social justification for buildings or signs that define its sides. The conventional building-to-street relationship, however, dissolves along the interstate highway system. Motorists cannot reach buildings directly from the high-speed roadway. The result is the disassociation of building from street infrastructure; the interstate highway exists visually independent of buildings. Its formal organizing principle is the green veil rather than adjacent buildings or signs. Like insulation surrounding electrical wiring, the landscape visually isolates the roadway from buildings and other roads, first by a uniformly deep band of lawn to either side, and, in some instances, by a border of trees. This fragmented, green-veil concept is extended to perimeter center roadways at all hierarchies of scale. Garden is substituted for building and roadway as the principal ground of the new city. Unlike the conventional American city or the Strip, in which buildings and roadways define each other, it is the garden network of roadway green veils that provides the most basic continuity of perception in a perimeter center.
From chessboard to hourglass
The omnipresent arrangement of streets in the conventional American city is the grid. In theory, the grid affords a nearly infinite potential for movement from one position to another. But like a chessboard, such variables as size, direction, turn limitations, and blockages may preclude certain permutations. By contrast, the citizen motorist in a perimeter center moves about in a morphological model that may best be characterized as an hourglass. Proceeding from home to work or the mall by automobile, the potential field of choices narrows in successive stages as the motorist approaches the perimeter-center interchange. His or her daily journey starts at the front door, then proceeds from the driveway through an extensive network of local capillary streets to two-lane, mid-speed collectors, to a regional highway, to an interstate access interchange, then to an interstate itself, and finally to a perimeter-center interchange.
It is this interchange, not the mall, that is the true focus of perimeter center. It is the single experience that all citizen motorists of the new city share daily. From the passage through the vortex of path and time, the potential for movement again expands outward with an increasing array of choices available to the motorist as he or she nears the destination, be it office, mall, or store. Those choices are inversely related to speed of movement. The greater the speed, the fewer the choices (hence the term limited access); the lower the speed, the greater the potential number of destinations. The profound change in infrastructure from the chessboard to the hourglass model is in the dematerialization of connections between destinations that follows from limited-access highways. At the high speeds characteristic of travel on the interstate highway system, distance is collapsed so that 20 miles may be traversed in the same time that it takes to cross the 2 miles of the central Philadelphia grid, river to river. The result of these increases in distance between elements in the new city is an altogether new urban form that manifests itself with few conventional object-to-object connections. Nonetheless, with time -- not distance -- as the measure, this new city is arguably as dense as the conventional city.
The land bay as private garden
The separation of building from building and building from roadway in perimeter centers has been codified in the basic unit of perimeter centers: the land bay. The land bay is a ready-for-development parcel, complete with looping access road, utility infrastructure, and planning permits. It may vary in size, from a circumference of more than 1 mile to less than 500 feet, and it usually houses a single use with attendant parking.
In contrast to the land bay, the basic cell of the conventional city, the block, is a regular spatial unit that may be subdivided into hundreds of buildings or spaces, each with a different function, or it may be occupied by a single building or space. The subcellular structures that occupy the block are coded, typically through zoning ordinances, to exhibit conventional relationships to each other and to adjoining streets and sidewalks. The word block implies a unit to be assembled by addition or subtraction, or alternatively, to be carved away. It is entirely consistent with Nolli's image of the figured city as a solid form given comprehensibility by its voids. Conversely, the land bay conjures up an almost nautical image of amorphous space anchored above, shiplike, by a temporary tenant. In this sense, it is entirely consistent with the high-speed, self-mobile, driven world of perimeter center.
The zoning regulations that govern perimeter center, particularly setbacks and floor-to-area ratios, have come under recent widespread attack as the progenitors of anti-urban form. But these regulations are as consistent with the form of new perimeter centers as traditional urban zoning regulations, such as height and setback, are with the form of the conventional city. And that new form is a garden with buildings subservient to the garden. Perimeter centers can be interpreted as deliberate collections of individual land bays docked against one another; they are developed as privatized gardens in which one works, markets, and resides and that define a collective realm of sorts, interconnected by a network of green-veiled roadways.
The building in the garden
Within perimeter centers, building-to-garden relationships, not building-to-building relationships, are the only formally substantive morphology. The buildings themselves may be best analyzed as components of garden typologies, not as structures that exist independent of landscape. In Perimeter Center, north of Atlanta, this understanding is manifested by applying garden names to office complexes that would formerly have been referred to by number. And each such Office in the Garden is evocative of a landscape type. For example, Ravinia, a mixed-use office and hotel complex, is a hybrid of two landscape types: "ravine" and "arcadia." It is the ravine, complete with stream and waterfalls in a densely wooded arcadian landscape, that dominates Ravinia -- not the buildings, which are only obliquely perceived through the garden. The operative image here is Asher Durand's 19th-century vision of contemplation in the American wilderness, with the office structure, not a rock outcropping, becoming the new vantage point for observation of the garden.
Just as the workplace in a perimeter center may be understood through reference to landscape, so too the mall may be comprehended as a composite landscape/parkingscape. The mall is not Main Street, namely a mixed-use outdoor space accessible to wheeled vehicles and pedestrians. It is a privatized mercantile wintergarden centered within an asphalt parterre of parking lots and encircled by a green-veiled loop road. It displaces our retail experience from the 19th-century streetscape to the climatized garden.
The typical perimeter center residence is either a single-family detached house with front-, side-, and rear-yard setbacks, or a townhouse or garden apartment on an attached, multifamily development. It is the most extended component of the new city, and it may be located anywhere within a 45-minute commute of the citizen motorist's destination. This means that, given the maximum 55-mile circumference of most central city beltways, perimeter center workers and shoppers may live anywhere within a metropolitan region. In this regard, Frank Lloyd Wright's Broadacre proposal, with its even dispersal of houses on 1-acre plots stretched across the continent, has proved prophetic of perimeter center development.
New form of paradise
The modern vision of the city in the garden has not yet evolved as Ebenezer Howard, Le Corbusier, and Wright had hoped, through displacement, replacement, or absorption of the central city, but has come to pass as a new peripheral Eden coexistent with the central city. The terrace view of Le Corbusier's Villa Contemporaine can be likened to developers' visions of life in perimeter centers. In short, the vision has come to pass, but it's been displaced to the urban perimeter. Moreover, the uniform landscape topographies of both Villa Contemporaine and Broadacre have given way in perimeter centers to specificity of individual landscape types. Le Corbusier's desired reduction to a single object-type, applied to both landscapes and buildings, is diffused in the hands of developers to a kaleidoscopic landscape that is consistent with our market economy and politics. Rather than a single public garden, the new city is a collection of privatized gardens, each designed to be unique and easily distinguished from its competing neighbors. Each garden is also separated from its neighbors by a green veil and by patterns of automobile access that stress discord, discontinuity, and distinction to enhance marketing. A modern Eden has indeed been attained: in a perimeter center, the garden precedes all else and lends the center its form and substance.
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