Urban planning

Urban, city, or town planning, deals with the physical, social and economic development of metropolitan regions, municipalities and neigrborhoods. Other professions deal in more detail with a smaller scale of development, namely architecture, landscape architecture and urban design. Regional planning deals with a still larger environment, at a less detailed level. The Greek Hippodamus is often considered the father of city planning, for his design of Miletus, though examples of planned cities permeate antiquity. Muslims are thought to have originated the idea of formal zoning (see haram and hima and the more general notion of khalifa, or "stewardship" from which they arise), although modern usage in the West largely dates from the ideas of the Congrès Internationaux d'Architecture Moderne.

Planning and transport

There is a direct, well-researched connection between the density of an urban environment, and the amount of transport into that environment. Good quality transport is often followed by development. Development beyond a certain density can quickly overcrowd transport.

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Good planning attempts to place higher densities of jobs or residents near high-volume transport. For example, some cities permit commerce and multi-storey apartment buildings only within one block of train stations and four-lane boulevards, and accept single-family dwellings and parks further away.

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Densities are usually measured as the floor area of buildings divided by the land area, or in a residential context, by the number of dwellings divided by the land area. Floor area ratios below 1.5 are low density. Plot ratios above five are very high density. Most exurbs are below two, while most city centers are well above five. Walk-up apartments with basement garages can easily achieve a density of three. Skyscrapers easily achieve densities of thirty or more. Higher densities tempt developers with higher profits. City authorities may try to encourage lower densities to reduce infrastructure costs, though some observers note that low densities may not accommodate enough population to provide adequate demand or funding for that infrastructure.

Related Topics:
Floor area ratio - Exurb

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Automobiles are well suited to serve densities as high as 1.5 with basic limited-access highways. Innovations such as car-pool lanes and rush hour-use taxes may get automobiles to neighbourhoods with plot ratios as high as 2.5.

Related Topics:
Automobile - Highway - Car-pool lane - Rush hour

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Densities above 5 are well-served by trains. Most such areas were actually developed in response to trains in the middle 1800s, and have historically high ridership that have never used automobiles for their work trip.

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A widespread problem is that there is a range of residential densities between about two and five that causes severe traffic jams of automobiles, yet are too low to be commercially served by trains or light rail. The conventional solution is to use buses, but these and light rail systems may fail where automobiles and excess road network capacity are both available, achieving less than 1% ridership. Some theoretricians speculate that personal rapid transit might coax people from their automobiles, and yet effectively serve intermediate densities, but this has not been demonstrated. The Lewis-Mogridge Position claims that increasing road space is not an effective way of relieving traffic jams as latent or induced demand invariably emerges to restore a socially-tolerable level of congestion.

Related Topics:
Train - Light rail - Bus - Personal rapid transit - Lewis-Mogridge Position - Latent or induced demand

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