Proposal for Compact Urban Growth in Adelaide

Michael Robertson and Andrew Tidswell. 2007.9.3

Urban Ecology Australia submission to Planning SA concerning proposed changes to Adelaide's urban growth boundary.

Proposal

Future urban growth in Adelaide should occur within established urban areas, close to activity centres and along public transport corridors, preferably within 10 km of the metropolitan centre. It should not occur on the periphery of the metropolitan area, some 40 or 50 km from its centre.

Well-planned urban consolidation in combination with faster, more frequent public transport, better developed local urban centres offering a greater variety of jobs, shops, and other facilities, and improved pedestrian and cycling paths, would help:

Reduce passenger car use.
Minimise car dependency.

Reducing passenger car use would:

Reduce world demand for transport fuel, and so make it more affordable for developing countries.
Reduce global greenhouse emissions and hence slow global warming.
Make urban roads safer, and main road precincts more attractive to residents, workers and visitors.

Reducing car dependency

By reducing the distances people need to travel, a compact city facilitates public transport, cycling and walking as an alternative to passenger car use. Not owning a car is much less daunting to people living nearer the centre of the metropolitan area, where job opportunities, shops, community facilities and social options are more densely clustered and therefore more easily accessed without a car.

Creating a city in which it is easy to access the benefits of urban life without needing to own a car would lift this financial burden from households on a low income, and allow much of the land and building space set aside for car movement and parking to be used for other purposes.

A compact city is more resilient to transport fuel price rises. If the world oil price continues to rise (due to rising world demand coupled with inability of cheap fuel sources to increase supply), then many low-income households will respond to the higher cost of running a car by turning to public transport. Coping with this extra load will prove more costly in sprawling cities than in compact ones, especially if the new users insist on public transport services with a speed and convenience comparable to that offered by the car.

Reducing World Demand for Transport Fuels

Reducing Adelaide's demand for transport fuel has a direct effect on prospective world demand (world demand = Adelaide demand + rest of the world demand), but the effect is small.

However, as a sprawling, low-density city that successfully reduced its demand for private, motorised transport (by becoming more compact, etc), Adelaide could have a significant indirect effect on world demand for transport fuel, by providing a model for many sprawling, low-density cities in the United States. These cities, which face similar problems to Adelaide, would closely scrutinize any solutions Adelaide developed.

A significant rejection by US cities of the car-based passenger transport model and development of alternative models of urban wealth and functionality, might slow the growth in demand for transport fuel in China, India, and other developing countries, whose expanding higher-income classes are influenced by the "prosperity = consumption" paradigm so celebrated in the United States and elsewhere.

Less world demand for transport fuel would be good news for many low-income communities in the world which rely on liquid fuel for electricity and freight transport, and have been hard pressed by rising petroleum prices. Benefits of mixed-use urban centres linked by public transport

Access by public transport, walking and cycling in Adelaide would be enhanced by developing numerous, small, mixed-use centres located along public transport routes within walking distance of most homes. Such centres would combine medium-density housing with a variety of commercial and light industrial activities. If your local centre did not have what you needed, it would be easy to catch a bus, tram or train to a centre that did. A proliferation of mixed-use centres, each hosting a variety of options, would be in contrast to the current situation in many areas of Adelaide, in which urban functions in are segregated, with housing in one district, industry in another, and shops set apart in large, exclusive blocks moated by extensive car parks.

Urban Regeneration for Improved Liveability

Many urban precincts along main roads are degraded from the point of view of urban liveability - disfigured by carparks and excessive road width, and subject to the noise, pollution, and pedestrian-injury-risk of passing motor vehicles.

Reducing vehicle traffic would make these environments healthier and more pleasant, and free up roadside space for buildings, trees, outdoor furniture and other amenities.

A main road intersection, for example, should not just be a place you pass through on the way to somewhere else. It should be a place you can visit just to enjoy that environment.

Ground-floor shops fronting onto wide, landscaped footpaths, (instead of large carparks abutting narrow footpaths), would make main road precincts more interesting to visitors and more supportive of emerging commercial enterprises. Small, street-side shops with cheap rental in village-like neighborhood centres are a good incubator for emerging, perhaps quirky small businesses. (Large, enclosed shopping centres, on the other hand seem to favour big-name chain stores or generic, high-volume food outlets).

Housing Affordability Without Urban Sprawl

A one-story house built on cheap, broad-acre land at the edges of metropolitan areas, can be cheaper per square meter than an equivalent house on expensive, inner-city land, even when the cost of new infrastructure is taken into account. Moreover, allowing unconstrained urban growth at the edges may reduce demand for housing in more established areas, thereby making such housing more affordable.

The challenge to proponents of compact cities then is: How can we increase the supply affordable housing without letting our cities continue to expand at the edges? One way of providing affordable housing in established urban areas is by building smaller dwellings there. High housing prices in Adelaide are due in part to the fact that there are few housing units for rent or purchase that are less than 50 square metres in size. Many one-person households that would be comfortably accommodated in dwellings of 30 square metres, are forced to live in dwellings twice this size for lack of choice.

Supply of small housing units is constrained by:

Zoning regulations which set minimum dwelling areas, require attached car-parking space, and limit heights in residential areas to one story.
Increasing demand for larger houses, which take up residential land that could have been used to build apartment buildings and other multi-unit clusters.

The demand for larger houses is partly due to a political and financial system that encourages residents to invest in the amenity of their private space, while denying them the opportunity to direct public investment in the amenity of their community space. Policies encouraging more compact cities would increase the funding available to neighbourhood amenity, and give local residents a greater say in how that money was spent.

Population Increase Without Urban Sprawl

Assuming that Adelaide's population will grow to 1.5 million by 2050 (water supplies permitting), how should the extra half million people be accommodated within the existing urban area?

Many railway stations on the current rail network, especially those located near commercial hubs, provide opportunities for more intensive, residential and mixed-use development. Similar developments can be planned along major roads to create transport hubs and medium density living where commercial development is already concentrated, ideally at major intersections where the radial and cross city roads intersect.

Adding 60 people per hectare to a zone 300 metres in radius around 20 railway stations would add 34,000 extra people. Adding 100 people per hectare to a zone 50 metres either side of 300 km of main roads would add 300,000 people. Adding 40 people per hectare to a zone 200 metres either side of 300 km of main roads, would add 480,000 people.

Concentrating a variety of destinations into a network of development zones along main roads would facilitate movement across the metropolitan area using the public transport that serviced these corridors.

Encouraging such development will require a change in land-use zoning to allow developers to build medium density housing over shops and other facilities. Plus traffic calming and landscaping along main roads to make them more attractive as places to live.

Need for Better Planning

At present there is some resistance to increased urban consolidation due to the unplanned and ad-hoc way in which it generally occurs in isolated pockets of the suburbs. We need good examples to demonstrate how urban consolidation can be done well, in order to gain public support.

Poorly planned urban consolidation results in loss of heritage buildings and gardens, and increased local vehicle traffic, to the dismay of established residents. Locating higher residential densities in mixed-use centres along main roads, combined with significant traffic-reduction measures, would help resolve these concerns.

Adelaide, with its single, accessible CBD and logical network of road and rail routes, is an ideal city to convert from a sprawling, car-based city to a more compact, transit-city. Developing this as a strategic planning priority would build on the legacy of earlier planning from Colonel Light onwards.

Such a transition would help realise the goals of South Australia's Strategic Plan, in particular improving wellbeing, attaining sustainability, fostering creativity and innovation, and building communities. And it would demonstrate that South Australia was serious in its intention to lead the world towards a more sustainable and liveable future.

2007.10.24