Environmental Engineering Reference
In-Depth Information
walk/bike trips. As well the inner/core has three times the level of public
transport use with 0.66 trips per person per day compared to 0.33 trips in
the outer/fringe. In Sydney 17 per cent of people in the outer suburbs use
public transport for work but in the inner suburbs it is 33 per cent.
To make it worse, the people who are most car dependent are the least
able to afford it. So the question boils down to how we can begin to reduce
car dependence in Australian cities, especially in the outer areas, in ways that
do not make inequalities worse.
The models of how Australian cities need to be planned are being set out
in all the planning systems mentioned above. They are showing the impor-
tance of new, more viable subcentres, especially in outer areas, linked by
quality public transport routes (both into the city centre and around it) that
are faster than the car traffic in those corridors. They also reflect a clear
policy of restraining growth at the fringe and therefore concentrating devel-
opment into these centres.
Overcoming car dependence then comes down to two major issues: (1)
how to increase the viability of alternative transport modes in corridors and
in local areas, and (2) how to create viable centres that will enable good
public transport to be provided and to encourage sufficient services locally
in such centres.
The first issue is reasonably well known and is just a question of funding
priorities (see below). The second is less well known. From data collected
globally and locally there is evidence of a minimum level of density of popu-
lation and jobs (development intensity) that needs to be reached before car
dependence can be adequately addressed. This minimum development
intensity level is around 35 people and jobs per ha (Newman 2004). Once
the level of activity reaches this kind of intensity then the level of car use
drops dramatically and alternative sustainable transport modes begin to be
genuine options. Similar patterns are found in the world's cities where a 35
per ha minimum seems to be associated with car dependence in general.
What this means in urban design terms is that the number of people and
jobs in centres needs to be planned to try and reach this level. If a small centre
were to be built around a rail station then a viable number of people and jobs
within 1 km radius of the centre would be around 10 000. If a major regional
centre was to be built it would need around 100 000 people and jobs within a 3
km radius for it to be a viable centre. If centres don't reach these numbers then
they need to bring people from further out and the time/space limitations of
