Urban Quarter and Polycentric Cities

Neighborhood Structure

• The question being explored is how the idea of a neighborhood has been conceptualized in terms of its physical form.
• Leon Krier's concept of the polycentric city of urban communities is a basis for exploring ways to conceptualize neighborhood structure.

The Polycentric Idea

• A "mature" city cannot expand without sacrificing its essential qualities.
• Cities can grow by reproduction and multiplication becoming polycentric and polynuclear.
• The autonomous urban quarter serves as the fundamental building block. It is a true city within a city.

Urban Quarter Basics

• An urban quarter is a built environment that supports the collective and individual self-interests of a community.
• It is the basic component of every city.
• The urban quarter is largely self-sufficient.

Urban Quarter: Structural Components

• An urban quarter is autonomous with respect to kindergartens, primary schools, daily grocery shopping, markets, health services and cultural activities.
• A city is autonomous for monthly and seasonal shopping, administration, sport, services, culture, and leisure activities at a regional level.

Urban Quarter: Structure and Form

• An urban development significantly reduces the distance a person travels daily between their workplace, home, school, shops, and leisure activities.
• Neighborhood size is determined by daily pedestrian capacity. Pedestrians must access daily and weekly urban functions within a ten-minute walk, without using transport.
• The ideal area would be 500-600 m in diameter, or about 80 acres which is 30-40ha. One acre equals 4 Dunums, so roughly 300-400 Dunums.
• An urban quarter should be rounded and not sprawling.
• It should not extend more than 900m in any one direction.
• An urban quarter should not exceed 10,000 inhabitants and users.
• Urban quarters should have a clear hierarchy of streets and squares in a regular or irregular grid pattern or a mix of both.
• Each quarter needs a central square with a denser street network. The street network generates a feeling of centrality.
• Each quarter also requires at least one high street forming the backbone of the street and square network.
• A street network's efficiency is measured by its number of T-junctions and crossroads.
• The number of street corners indicates urbanity. The number of cul-de-sacs indicate a lack of urbanity.
• Cul-de-sacs and one-way streets should be avoided unless topographical conditions are exceptional.
• Boulevards, avenues, large squares, public gardens, fairgrounds and golf courses should not be inside urban quarters, but form its boundaries.
• Avoid flattening hills, filling valleys, and reducing inclines. Enhance distinctive site characteristics.
• Urban plans and skylines should take advantage of the specific nature of the topography.

Sitting of Buildings

• Dominant geographies should be reserved for significant buildings with high symbolic value.
• Public buildings for local use should be located within the quarter. Metropolitan, regional, or nationally important buildings should be on main squares, avenues, and boulevards bordering the quarters.

Urban Spaces

• Urban Space (public space) is a void with dimensions, forms, and characteristics.
• Public spaces can only be in the form of linear spaces (streets) and nodal spaces (squares).
• Public spaces should take up 25%-35% of a quarter's total area; too little is a false economy and too much, a false luxury.
• Public spaces organize into regular or irregular patterns and grids of avenues, boulevards, streets, squares, alleyways, courtyards, parks and gardens.
• Regular geometric and parallel public spaces need high architectural order. Streets and squares with non-parallel configurations can accommodate modest architecture.
• Modest architecture is generally inappropriate for highly formal public spaces.
• A good city or urban quarter plan uses all geometric and topographic devices, avoiding excessive regularity and enforced irregularity.

Circulation Hierarchy

• Through traffic must be at a tangent to urban quarters.
• Traffic is channeled along streets, boulevards, and avenues that create the urban quarter's physical boundaries.
• Vehicular and pedestrian movements need distinct spaces.
• Narrow, interlinked pedestrian alleys cut across urban blocks, creating a car-free network within each quarter.
• The central square of a quarter is reserved for pedestrians while parts of the high street could be closed to traffic at certain times.
• Cars can park parallel to the kerb on one side of most streets.
• Control vehicle speed through street and square design instead of signs and gadgets. Use geometric configuration, profile, paving, planting, lighting, street furniture and architecture.

Polycentric Zoning of Functions

• Commercial use should be permitted on the ground floor along the high street and in the central square, but not above the mezzanine or below ground floor.
• Small, medium businesses, nonresidential, and nonpolluting uses should have a place within the quarter.
• Locate large firms and large-scale non-residential uses on the perimeter of the quarters, fronting large avenues and boulevards.
• Public and civic functions should be dispersed and intermixed and not concentrated in specialized areas.

Building Heights

• Building heights should be limited by the number of floors not metrics, with a limit of two to five floors. The character of the city, building use, road width, and prominence of the site all weigh on height decisions.
• The plot ratio (ratio of floor area to plot area) should be 2:1, similar to historic cities.
• This density can be achieved with buildings of three to five floors, providing well-lit, well-proportioned private gardens and public spaces.