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ARIA

The Accessibility/Remoteness Index of Australia (ARIA) continues to be developed and maintained by the Hugo Centre. ARIA was created as a joint project with the Australian Department of Health and Ageing in 1998. The most widely used ARIA product is ARIA+.

ARIA map

ARIA+, like its predecessor ARIA, is an unambiguously geographical approach to defining remoteness. ARIA+ is a continuous varying index with values ranging from 0 (high accessibility) to 15 (high remoteness), and is based on road distance measurements from over 12,000 populated localities to the nearest Service Centres in five size categories based on population size.

The resulting index is a 1km grid covering all of Australia for which accessibility/remoteness values can be extracted for any geographic location of interest.

The major advantages of ARIA over other methods of measuring remoteness are;

  • it is a purely geographic measure of remoteness, which excludes any consideration of socio-economic status, 'rurality' and populations size factors (other than the use of breaks in the population distribution of Urban Centres to define the Service Centre categories);
  • it is flexible and can be aggregated to a range of spatial units, used as a continuum or classified;
  • its methodology is conceptually clear;
  • it is precise; and
  • it is relatively stable over time.

As a comparable index of remoteness that covers the whole of Australia, ARIA provides a measure of remoteness that is suitable for a broad range of applications including assisting in service planning, demographic analysis and resource allocation.

ARIA provides a remoteness, or accessibility, value for every location in Australia (to 2 decimal places), and can be purchased for Australian Bureau of Statistic (ABS) geographies and non-ABS geographies (eg Local Government Areas) as well as scores of each populated locality/town used in the creation of the index.

View ARIA+ 2011

View ARIA+ 2001 & 2006

Purchasing ARIA Scores

The Hugo Centre currently distributes two versions of ARIA (ARIA+ & ARIA++) for three different time periods (2001, 2006, and 2011). To purchase an ARIA product, please use the ARIA Order Form to place an order online. For more information or assistance with placing an ARIA order, please email the Hugo Centre

The 2016 version of ARIA is planned for release in early 2018. If you wish to be notified when ARIA 2016 is available, please email us your contact details.

ARIA+ Methodology

ARIA+ measures remoteness in terms of access along the road network from populated localities to each of five categories of Service Centre based on population size, as indicated in the below table. If one thinks of ARIA as based on the distances people have to travel to obtain services, then populated localities are where they are coming from, and Service Centres are where they are going to.

Service Centre Category Urban Centre Population
A 250,000 persons or more
B 48,000 - 249,999 persons
C 18,000 - 47,999 persons
D 5,000 - 17,999 persons
E 1,000 - 4,999 persons
F (ARIA++ only) 200 - 999 persons

The ARIA+ methodology regards services as concentrated into Service Centres. Populated localities with populations of greater than 1,000 persons are considered to contain at least some basic level of services (for example health, education, or retail), and as such these towns and localities are regarded as Service Centres. Those Service Centres with larger populations are assumed to contain a greater level of service provision.

The road distance from each of the 12,000+ populated localities to the boundary of the nearest Service Centre in each category was calculated. This calculation resulted in five distance measurements being recorded for each populated locality, one for each Service Centre. Populated towns within a Service Centre (based on ABS-defined Urban Centre boundaries) in the relevant category were given a distance value of zero for that category. Each distance value was divided by the Australian average (mean) for that category in order to derive a standardised (or ratio) value. Distance measurements are standardised so that large distance measurements would not overwhelm the effect of the other distance measurements.

Each ratio value is thresholded at three (i.e. three times the Australian mean) to remove the effects of any remaining extreme values from the index. All towns with a ratio value higher than three for a given category are considered 'remote' in terms of access to that category, and were given a value for that category equal to the threshold. For each populated locality, the standardized value from each of the five Service Centre categories is summed to produce an overall index value ranging between 0 and 15. The lower the value, the greater the access to services.

An interpolation procedure is then used to derive the index values for each of the localities to a 1 km grid so that all areas of Australia are able to be assigned an index value.

Example ARIA+ Calculation

The example below shows how the ARIA+ 2011 score for Pine Creek is calculated (Please note: rounding has been applied for the purpose of this example).

The locality of Pine Creek in the Northern Territory is:

  • 2,819 km from the nearest Category A Service Centre (Adelaide)
  • 212 km from the nearest Category B Service Centre (Darwin) 
  • 212 km from the nearest Category C Service Centre (Darwin)* 
  • 92 km from the nearest Category D Service Centre (Katherine) 
  • 92 km from the nearest Category E Service Centre (Katherine)**

Next, divide by national average for each category:

  • Its Category A score is 2,819 / 418 (national average for category A) = 6.74 {exceeds threshold so score = 3.00}
  • Its Category B score is 212 / 217 = 0.98
  • Its Category C score is 212 / 132= 1.61
  • Its Category D score is 92 / 84 = 1.10
  • Its Category E score is 92 / 47 = 1.96

The ARIA score is thus 3.00 + 0.98 + 1.61 + 1.10 + 1.96 = 8.65

* There were no Category C Service Centres closer to Pine Creek than Darwin, so Darwin functions as both the closest Class B and Class C centre.
** There were no Category E Service Centres closer to Pine Creek than Katherine, so Katherine functions as both the closest Class D and Class E centre

Although ARIA+ provides a measure of accessibility and remoteness for the whole of Australia, including metropolitan and non-metropolitan areas, the principal focus of the index has been to quantify accessibility in non-metropolitan Australia. This is not to deny the importance of service access issues within major urban areas, but a detailed analysis of accessibility within urban areas is believed better served by a dedicated methodology - Metro ARIA.

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hugocentre@adelaide.edu.au

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