Fused Grid - Terminology and History

Terminology and History

Aristotle, a pre-eminent philosopher and classifier, when writing about Hippodamus and his works a century hence, has no typological name for either his new city layout system or for the pattern that preceded it. It is now often called, erroneously, the Hippodamian grid. The grid pattern had emerged earlier elsewhere.

Twentieth century urban planners classify street networks into “organic” and “planned”; very general categories. Planned networks are invariably geometric, an intentional and studied application of a chosen geometry, while the organic are believed to emerge from spontaneous, unguided growth. Planned networks include mostly a wide variety of “grids” and occasionally polygonal, circular or other mixed geometries.

Architectural historian Spiro Kostof writes that “The word 'grid' is a convenient, and imprecise, substitute for 'orthogonal planning'. 'Gridiron' in the US implies a pattern of long narrow blocks, and 'checkerboard' a pattern of square blocks”. In addition to the right angle being a key characteristic, a second attribute of equal importance is its imputed openness and unconstrained expandability. Loosely interpreted, the term “grid” can be applied to plans such as the Vitruvian octagonal plan for an ideal city, resembling a spider web, or to plans with radiating streets intersected by consecutive circular streets. These are all “grids”, “grates” or “griddles” in that a regularly spaced armature leaves recurring openings and that they could, conceivably, expand outward. (To avoid confusing the strict orthogonal grid with its loose interpretations the term “grid-type’ will be used in the subsequent sections of this text.)

The emergence of the pure, rectilinear, orthogonal grid, or Hippodamian grid, is explained by the natural tendency of people to walk in a straight line, particularly in the absence of obstacles and on level land. This intuitive explanation leaves the question of pre-grid and post grid non-rectilinear city patterns to be better understood, particularly those on plane territory such as Marrakech. Another potential influence may have been exerted by the second frequent user of city streets – horses. Horses also tend to move in a straight line, particularly at trotting, canter or galloping pace. When horses serve a city and draw chariots singly or in pairs, or, similarly, carts for a variety of transportation and processional functions, straight line travel becomes imperative; turns force a sluggish pace and cumbersome manoeuvres that reduce their efficiency of movement. The need for speed accentuates with city size; distances to the public functions at the centre increase and, consequently, the need for quick access intensifies. Speed in turn implies straight lines. It is plausible that the drivers for rectilinear layouts may have been man’s horses, mules and carts as much as man himself, spurred by the growth of settlements. The creation of the Radburn pattern is attributed to Clarence Stein but has a lineage of ideas that preceded it in Raymond Unwin and Barry Parker’s work that included the use of cul-de-sac and crescent street types. In contrast to the scarcity of records that obscures the original rationale for the grid, the reasons for the Radburn pattern has been articulated clearly in Stein’s writings and those of his predecessors.,

“Radburn” (after a place in New Jersey) now denotes a street network configuration. It signifies a departure from the strict orthogonal geometry and regularity of the grid and a distinct approach to laying out new districts. As a system, it can be described more accurately as a “cellular” network that has a characteristic hierarchy of streets as distinct from identical streets intersecting at regular intervals. Its derivatives and idiosyncratic imitations are often characterized as “cul-de-sac and loop” patterns highlighting the distinguishing street types that are used systematically in this network. A second term equally uncharacteristic is “suburban”. This association of a pattern with a location is inaccurate and unintentionally misleading: entire early cities such as Cairo and Fez are structured on this pattern whose newer suburbs follow the grid reversing the urban/suburban relationship. “Suburban” is also devoid of geometric descriptors of the pattern. These shorthand expressions conceal the variety of patterns that emerged in the 20th century that are decidedly neither grids nor “Radburn” and the "system" aspect of the pattern. The “loop and lollipop” label may be a more applicable descriptor of later interpretations of the Radburn model that appear to lack structure and to overlook key elements of the original concept such as its emphasis on pedestrian priority, for example. The pattern’s systematic use of the cul-de-sac and loop is decidedly linked to automotive mobility as a means of controlling and guiding its flow. The Radburn pattern is a complex system; more than a series of identical orthogonal city blocks in a linear progression. It rests on a functional program plus an intentional picturesque aesthetic: it avoids straight lines, limits four-way intersections and shuns repetitive blocks all of which enhance its picturesque imagery. To facilitate the discussion, the name “Radburn-like” or “Radburn-type” will be used in the subsequent sections.