A comparative study of block size and form : (in selected new towns in the history of western civilization and in selected North American and Australian city centres)

Abstract

AimsThe study is concerned with the size and form of city blocks, one of the fundamental elements of the physical structure of urban areas. It was suggested by the lack of comparative factual information about the types, shapes, sizes and arrangements of blocks employed in different periods and places, and about the relative performance characteristics of different block forms in terms of circulation, land use and building forms.The aims of the study are to examine and compare:1) the block forms and sizes used in the main historical periods of new town foundation;2) the relative performance characteristics of selected North American and Australian city centres having different block forms and sizes.The study is conducted in two distinct but related parts reflecting these aims.ScopeThe scope of the study of block forms and sizes in history is limited to new town foundations in the following periods - Greek, Roman, medieval, and 17th to 19th century America and Australia. All these periods are pervaded by relatively similar colonial settlement objectives and circumstances. The common British influence on American and Australian settlements also gives them a similar cultural background for comparative purposes. The choice of countries and towns examined in each period has also been determined by the availability of suitable plans or texts for the examination of block sizes and forms. Comparative data and graphical illustrations are provided for each period, and the reasons for the use of different block sizes and forms is analysed, with a view to identifying any typical, or most common, block forms which might apply in particular periods or places.The scope of the study of performance characteristics of different block sizes and forms in city centres is confined to six North American and six Australian cities, covering the widest possible range of block sizes and forms but also having some unique or related features. Savannah is a unique case of small blocks arranged in a special layout. Portland and Seattle contain small square and rectangular blocks, while Chicago and Indianapolis are composed of medium square blocks. Brisbane and Melbourne have medium rectangular blocks; Perth, Adelaide and Toronto consist of very large rectangular blocks. As a contrast to the regularly planned cities, Sydney and Hobart possess varied and irregular block forms inherited from their less considered initial layouts.Both the evolution and the present performance of these cities is analysed systematically in terms of land uses and parcelling, building forms and circulation patterns - attempting to identify the effect produced by different block sizes and forms. In addition to examining each city, a comparative analysis of their relative properties and performance characteristics of the twelve different block forms is also undertaken.ConclusionsThe main conclusions of the study are that:• The choice of different block sizes and forms in the main historical periods of new town foundation has been determined primarily by the initial development requirements in terms of land parcelling.• Each period shows some degree of consistency of block size and form, and a predominant type of block can usually be identified, at least for particular geographical regions and sub-periods. This is caused primarily by similarity of functional requirements, but sometimes by the existence of planning regulations or the adoption of similar planning, surveying, and land subdivision practices.• In the city centres studied, layouts initially having different lot and block size and forms have, over time, tended towards similar patterns of land parcelling, building forms, and circulation routes as a result of their similar urban purposes and processes.• In the city centres of Australian and North American cities, certain forms, sizes and arrangements of lots, blocks and streets have been more adaptable, and have performed better for past and present requirements.• It has been possible to identify blocks forms and dimensions having optimal performance in certain aspects or circumstances, and to indicate predictable consequences and processes of other block forms and dimensions