Accessibility/Remoteness Index of Australia (ARIA+)​
​The Accessibility/Remoteness Index of Australia (ARIA+) is the leading Australian indicator of remoteness.
ARIA+ is an objective geographic measure designed to quantify remoteness across Australia.
About ARIA+
ARIA+ is a detailed, objective and nationally consistent measure of remoteness in Australia. Developed by the Australian Centre for Housing Research, ARIA+ has become the standard for classifying the accessibility and remoteness of locations across the country. ARIA+ is used in government and policy, research, and academia, and is used in the development of the Australian Bureau of Statistics (ABS) Remoteness Areas, Australia’s official classification of national remoteness.
Advantages of ARIA+
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It provides a nationally consistent measure of accessibility/remoteness, allowing the accurate comparison of any locations across the whole of Australia;
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it is a purely geographic measure of remoteness, which excludes any consideration of socio-economic status, 'rurality' and population size factors (other than the use of breaks in the population distribution of Urban Centres to define the Service Centre categories;
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it is flexible and can be aggregated to a range of spatial units, used as a continuum or classified;
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Its methodology is conceptually clear;
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It is precise; and
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It is relatively stable over time.
How ARIA+ is Calculated
ARIA+ is a continuous scale, with scores ranging from 0 (high accessibility) to 15 (high remoteness). ARIA values are calculated using road distance measurements from over 12,000 populated localities to population ‘Service Centres', each defined by population size.
The ARIA+ methodology assumes that Service Centres with populations of more than 1,000 persons contain at least some basic level of services (e.g. health, education, or retail), and that those with larger populations contain increasingly greater levels of service provision. The population thresholds for Service Centres are as follows:
Category
Urban Centre Population
​​A
B
C
D
E
250,000 persons or more
48,000 - 249,999 persons
18,000 - 47,999 persons
5,000 - 17,999 persons
1,000 - 4,999 persons
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 category). 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 to derive a standardised (or ratio) value. Distance measurements are standardised so that large distance measurements do not overwhelm the effect of the other distance measurements.
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Each ratio value is then thresholded to a value of 3 (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 standardised 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.
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The resulting index is a 1-kilometre grid covering Australia, from which accessibility/remoteness values can be extracted for geographic locations of interest. ARIA provides a remoteness, or accessibility, value for every location in Australia (to two decimal places), and can be purchased for Australian Bureau of Statistics (ABS) geographies and non-ABS geographies (e.g. Local Government Areas) as well as scores of each populated locality/town used in the creation of the index.
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Example Calculation
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The example below shows how the ARIA+ 2021 score for Pine Creek is calculated*.
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The locality of Pine Creek in the Northern Territory is:
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2,818 km from the nearest Category A Service Centre (Adelaide)
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206 km from the nearest Category B Service Centre (Darwin)
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206 km from the nearest Category C Service Centre (Darwin)**
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91 km from the nearest Category D Service Centre (Katherine)
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91 km from the nearest Category E Service Centre (Katherine)***
Next, distances are divided by the national average for each category:
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Category A score is 2,818 / 412 (national average for category A) = 6.84 {exceeds threshold so score = 3.00}
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Category B score is 206 / 214 = 0.96
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Category C score is 206 / 133 = 1.55
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Category D score is 91 / 88 = 1.03
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Category E score is 91 / 46 = 1.98
The ARIA score is thus: 3.00 + 0.96 + 1.55 + 1.03 + 1.98 = 8.52
Although ARIA+ provides a measure of accessibility and remoteness for all of Australia, including metropolitan and non-metropolitan areas, the principal focus of the index has been to quantify accessibility in non-metropolitan Australia.​​​
* Rounding has been applied in this example. This example does not reflect the actual ARIA score of Pine Creek, Northern Territory.
** There were no Category C Service Centres closer to Pine Creek than Darwin, so Darwin functions both as the closest Class B, and the nearest Class C service 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