The following text summarizes the content of the first lecture for this course.
On Urban Form
Michael Dennis
A city has three constituent elements according to William Westfall:
"the political character of its citizens; their institutional arrangements; and the embodiment of their politics and institutions in architectural and urban form."
As architects and citizens we should be mindful of the first two of these. As architects and urban designers, however, our focus should be on urban form as the physical embodiment of the idea of the city.
The physical form of the traditional city is comprised of buildings, blocks, streets, squares, and parks that form neighborhoods and a legible civic structure.
The city may also represent the political aspirations of its citizens, but most cities have reflected different political aspirations over their history, and these are visible in their form.
Worldwide, cities exhibit more in common than in differences. Many physical attributes, such as typology, are persistent and cross-cultural. Indeed, it can be argued that the biggest changes in the long evolution of traditional urban form have been prompted by changes in technology - especially the technology of movement: e.g. the invention of the sprung carriage in the eighteenth century; the advent of the railroad and the elevator in the nineteenth century; and the advent of the motor car in the twentieth century. The traditional city loosened to accommodate this new condition of movement, and expanded to accommodate the urban population explosion precipitated by the industrial revolution. But all these changes utilized traditional urban typologies. Cerda's Barcelona is a particularly beautiful example.
In the mid-twentieth century a new, fundamentally anti-urban, architectural typology conspired with increased freedom of movement to challenge the hegemony and validity of traditional urban form. Until this time there was a symbiotic relationship between architecture and urbanism: architectural styles could change as desired because there was hegemony of the urban realm; when architecture achieved hegemony over urbanism, however, the public realm disappeared as a legible, spatial entity.
For many architects and urbanists today the reconstruction, or redefinition, of the physical public realm is a prerequisite for the continuation of quality urban life. The utilization of time-tested principles - those of the world's most beautiful cities - should be the basis of that effort.
The most fundamental characteristics of urbanity are density, spatial definition, and mixed uses. Other physical characteristics are also important: continuity, scale, pedestrian orientation, varied neighborhoods, uniqueness of place, possibilities of both community and anonymity, incremental growth, and possibility of movement through accommodation of the automobile and public transit. If the city is comprised of buildings, blocks, streets, squares, parks, neighborhoods, and a legible civic structure, a few basic principles suffice to guide development.
Urban Design Principles
Buildings
- Should (usually) be smaller than blocks
- Should align on streets or squares, with limited and proportional heights
- Should have legible fronts and backs
- Should have facades on streets and squares
- Should have articulate ground floors
- Should have expressive form appropriate to their public role
Blocks
- Should have clearly defined exterior edges
- Should be modest in size: ca 150-300' x 200-600'
- Should be consistent enough to make identifiable urban fabric
Streets
- Should be the minimum width required
- Should be a hierarchy from lanes to boulevards and avenues
- Boulevards, avenues, and some streets should be tree-lined
Squares
- Should have adequate spatial closure and legibility
- Should be of modest size: ca 200-400' x 300-600'
- There should be a hierarchy of neighborhood and civic squares
Parks and Gardens
- There should be a hierarchy of neighborhood and civic parks and gardens
Neighborhoods and Districts
- Should be of perceptible size
- Should have a clear center, identifiable fabric (and clear edge?)
Civic Structure
- Should have a legible form of the most important civic institutions and spaces