Geography Reference
In-Depth Information
analytical issue of how these independent zonal structures can be spatially
integrated into a single, consistent set of geographical units. To overcome this
problem, an area interpolation technique was applied to transform the spatial
data from the zones supplied by the ABS to a new set of spatial units which
are consistent between 1996 and 2006. We used 2006 suburbs as the new
destination zones (consistent to the origin zones) and applied an areal
weighted proportioning method to transform the spatial data. The data
estimation for the new destination zones was based on the degree of spatial
overlap with known data for the previous destination zones. Although the
concept of the technique is fundamental, it proved challenging as the areal
calculation for the large spatial matrix data was computationally intensive.
Finally, the results of the average commuting distance across suburbs for
year 1996 and year 2006 are provided in Figure 3 (a) and (b). This shows that
the commuting distance tends to be shorter among workers who live closer to
central city areas (e.g. Brisbane metropolitan area, Gold Coast and
Toowoomba City), whilst longer commutes (mainly cross-suburban travel)
tend to be for workers in the middle and outer suburbs. Therefore, the regional
trend is that the travel distance increases as residences are separated further
from the city centre. The further one's home is from a city centre, the longer
one's commute tends to be.
The result also reveals the local difference in average commuting distance
between 1996 and 2006. In general, there was minor change in average JTW
distance between 1996 (15.75 km) and 2006 (15.95 km). There were an
increased number of commuters travelling shorter distances to work (less than
10 km) by 2006, but the distance of travel for commuters in the middle range
(e.g. 10 to 30 km) slightly increased. The number of commuters with very long
commutes (30 km or more) remained stable between 1996 and 2006. By
comparing Figure 3 (a) and (b), the map shows that over time a decrease in
average commute distance occurred at the Sunshine Coast (far north to
Brisbane), Brisbane's west, and the Gold Coast suburbs. The possible reasons
include fast urban growth and employment relocation, which have introduced
increasing numbers of employment opportunities into these areas. People
living in these areas tend to find work locally, travelling relatively shorter
distances. In addition, areas with an increased commuting distance were
observed at some outer-urban and regional areas. Tentatively, the increase in
long commuting could be driven by economic restructuring, and new residents
in emerging peri-urban locations who are often reliant on employment well
outside their local area, perhaps explaining increasing general commute
distances.
