Urban Form

Discussion

Urban form can affect the ability of cities to provide their citizens with a good way of life while minimising impacts on nature and the depletion of natural resources.

A compact city in which everyone lives and works within walking or cycling distance of everywhere else, or a network of compact urban districts connected by rapid public transport, minimises the need for cars, and the impacts they cause.

A city that sprawls into its rural hinterland, whose urban centres are mostly large shopping malls girded by massive carparks, which is connected up by freeways, and in which very little is within easy walking, cycling or public transport use of anywhere else, will maximise the need for cars.

Readings

Reshaping Cities

Reshaping Cities for a Sustainable Future. CSIRO Manufacturing and Materials Technology.

See also: Reduce Air Pollution: Redesign Your City. CSIRO. 1998.10.20

The CSIRO study, Reshaping Cities for a More Sustainable Future, considers how different city forms would affect fuel consumption, greenhouse gas emissions, and exposure to photochemical smog and fine particle emissions.

Six alternative scenarios of future urban form are examined:

Business as usual – laissez faire, low density, dispersed.

Compact city – increased population and density of inner suburbs.

Edge city – increased population, housing densities and employment at selected nodes within the city, with increased investment in orbital freeways linking the edge cities.

Corridor city –growth along linear corridors radiating from the central business district, supported by improved public transport.

Fringe city – additional growth predominantly on the fringe of the city.

Ultra city – additional growth predominantly in provincial cities within 100 km of a capital city and linked by high-speed rail transport.

Predictions regarding exposure to photochemical smog and fine particles:

Already, the cost of air pollution to Australia is high: the human health cost is estimated at between $3 billion and $5.3 billion every year, and annual damage to materials, property and buildings is between $3 billion and $5 billion – 1% of GDP.

Cars are the biggest cause of air pollution. Because most Australians shun public transport and rely on cars to transport them around their sprawling cities, we are among the highest per capita air polluters in the world.

Most people have come to accept urban sprawl and driving long distances to work as a way of life – but this has to change. As the pollution increases, the livability of our cities will worsen, and their attractiveness to investment and tourism will deteriorate.

It is estimated that 88% of the world’s population growth next century will be in urban areas. Australia’s cities will continue to grow as places where ever-increasing numbers of people both live and work.

Housing Form

Australian Governments and Sustainable Housing. T. Playford. GEOView. 2001

Cities can negatively impact on the environment. Large numbers of people require large amounts of housing. The impacts of housing include the embodied energy in the building materials of the house, the physical space they occupy, the waste outputs they produce, and the energy that the people who inhabit them consume (in part influenced by the nature of the dwelling).

The environmental impact a dwelling has is also influenced by its position relative to the needs of its occupants, for example the proximity to workplaces or schools can determine the amount of transport energy they will use in travelling to work, school, or elsewhere.

The Australian government at all levels has tried to make housing more environmentally sustainable through a mixture of incentives, pricing strategies and legislation.

There have been some increases in residential density through urban consolidation. But higher densities do not automatically reduce transport emissions unless improvements are made to public transport systems

"Urban Village" type developments offer improved environmental performance, but unless adopted on a broad scale may not significantly alter the sustainability of urban housing.

Often there are conflicts of interest between departments or levels of government. Needed: a comprehensive, holistic set of strategies and targets that complement one another, from the Commonwealth level down to the local level.

Maybe the most important thing that needs to be addressed is people’s attitudes and values. In spite of the achievements of governments, car use continues to rise and most Australians still prefer to live in a detached family home on a separate block.

The One Hour Limit

Why We're Reaching Our Limits as a One-Hour City. Peter Newman, Sydney Morning Herald. 2004.4.26

How we want to use our time will determine how we want to build a metropolis.

Marchetti's Constant: The average travel time budget, around the world, in every city, is about one hour, per person, per day. If you take half an hour for the journey to work and home again then that's it. If you take less, you'll probably go walking with the dog or something but you'll take about an hour on average.

We need to have a restorative, reflective time.

[Thus] the city is always one-hour wide. The walking cities of the past - historic, medieval cities - were five to eight kilometres wide. You could walk across them in an hour. Victorian cities, the industrial revolution cities, spread out because the pipes and the rails meant that we could now travel 20 to 30 kilometres. And the city remained one hour wide.

[Motorways] spread the city out further. In an hour you could go 50 kilometres.

The Marchetti principle means that if you have a good public transport system there will be a market for dense, walkable development.

2007.7.16