William E. Rees and Mark Roseland

Developing sustainable human communities will require an unprecedented emphasis on reducing urban sprawl and its unsustainable consequences. Such an effort must simultaneously create more efficient use of urban space, reduced consumption of material and energy resources, improved community livability, and improved administrative and planning processes capable of dealing effectively, sensitively, and comprehensively with the social and environmental complexity of urban settlements.

Most North American cities were built using technologies that assumed an inexhaustible abundance of cheap energy and land. These communities grew inefficiently, becoming increasingly dependent on lengthy distribution systems. Cheap energy fostered an addiction to the automobile, and increased the separation of workplaces from homes.

Urban sprawl is the legacy of abundant fossil fuel and a perceived right to unrestricted use of the private car, whatever the social costs and externalities. Per capita gasoline consumption in many cities in the United States and Canada is now more than four times that of European cities. It is over 10 times greater than in high density cities like Hong Kong and Tokyo. These differences in consumption are not due to large car sizes and low gasoline prices, so much as differences in the efficiency and compactness of land-use patterns. Sprawling suburbs are arguably the most economically, environmentally, and socially costly pattern of residential development humans have ever devised.

The negative local and regional level consequences of sprawl - such as congestion, urban air pollution, and commuting distances between home and work - are now widely recognised. Less widely acknowledged are the global ramifications of North American land-use patterns. Largely because of low-density sprawl, the residents of Canadian cities produce about twice as much carbon dioxide per capita as do Amsterdam residents.

A San Jose, California study compared the environmental demands of 13,000 new residential units contained within an urban "greenbelt" with the same number if they were built in the usual exurban pattern. The exurban homes would require 200,000 more miles of auto commuting and three million more gallons of water per day. The exurban units would also require 40 percent more energy for heating and cooling than would their urban counterparts.

Cities with low "automobile dependence" are more centralised; use land more intensively; place more restraints on high-speed traffic; and offer better public transit, walking, and cycling facilities. This points to the considerable need for a new approach to urban transportation planning and traffic management. In the past several decades transportation planning has consisted largely of reacting to increasing highway congestion, which often is a direct result of the low-density outward expansion of the city, by building more highways. This pattern is painfully evident in many of the rapidly growing cities of the South, such as Manila, Jakarta, Bangkok. If sustainability is to be taken seriously, transportation planning must become a tool for inducing changes in the physical layout of cities.

Similar reforms are needed in urban land-use planning and controls. Metropolitan planning must shift away from the prevailing assumption that the primary urban access will be by automobile or even mass transit. Planning for sustainable urban centres must be based on the contrary assumption that people will be concentrated in the urban centre and that access will be determined primarily by the proximity of residences to work, recreation, shopping, and services.

Urban sprawl can be contained by setting limits on physical expansion and favouring alternatives to the automobile. Appropriate measures include limiting automobile access to inner cities, levying regional carbon dioxide taxes, restricting parking availability, and using traffic-calming street designs.

Governments, investors, and banks should all be required to analyse alternative long-term least-cost strategies for transportation and land-use investments. This would tend to give pedestrians, cyclists, and public transit riders priority over the automobile. It would favour building surface light rail and bikeway systems connecting higher density pedestrian-friendly city and suburban centres. It would favour building bicycle parking garages and policies that slow down car traffic to improve conditions for pedestrians and cyclists.

The models and strategies for limiting urban sprawl through innovative and provincial state planning, local government initiatives, and public-community partnerships are available. Promoting their more extensive use is an area that merits major attention from nonprofit organisations.

William E. Rees is a Professor in the School of Community and Regional Planning, University of British Columbia, Vancouver, Canada. Mark Roseland teaches in the Resource Management Programme at Simon Fraser University in Vancouver.

Source: PCDForum, based on their article "Sustainable Communities: Planning for the 21st Century".