The Australian Government's release of Administrative Boundaries and G-NAF under open data terms is now available on data.gov.au.
- How accurate are the boundaries in Administrative Boundaries?
- Why are there overlaps or gaps in boundaries?
- Database tables
- Included Data
- Australian Bureau of Statistics (ABS) data
How accurate are the boundaries in Administrative Boundaries?
The boundaries used to represent each feature within the Administrative Boundaries dataset have been collected from official government sources. These governments create these boundary representations using a variety of techniques, including:
- tracing (digitising) from aerial imagery or paper plans
- copying pre-existing representations of physical features (such as roads or rivers), and
- field-based surveys.
The dataset does not include information on how the representation of any boundary has been collected or how far away it is from the on-ground (real world) object it represents. Irrespective of how the boundary has been captured, the general practice within state and territory jurisdictions is to record any boundary representation to the nearest 0.001m (1mm). This figure effectively describes the resolution of the data and is typically expressed using the terms tolerance and precision within spatial sciences. This value does not mean that all boundaries are within 1mm of the true representation of any feature.
Why are there overlaps or gaps in boundaries?
All data within each theme contained in the Administrative Boundaries dataset includes representations determined independently by each jurisdictional authority and reflects their individual policies and responsibilities. PSMA is continuously working with the relevant authorities to improve consistency and alignment. Some things to note on specific types of data:
These boundaries reflect the responsibilities associated with each theme but misalignment will occur where each jurisdiction has different policies defining their area of responsibilities (eg. the distance of regulation out from the coastline). It is important to note that external boundaries should not be used as a representation of coastline.
As each jurisdiction has different policies for making a determination on representation then misalignment will occur. The Intergovernmental Committee on Surveying and Mapping (ICSM) is currently working towards the construction of single agreed national boundary representation.
The Suburbs-Localities theme within the Administrative Boundaries dataset can have overlapping polygons where they have different CLASS CODES. For example, in South Australia, there are features overlapping gazetted suburbs which represent a related class of locality known as ‘HUNDREDS’. Within the Australian Capital Territory, there are gazetted suburbs as well as ‘DISTRICTS’. All classes of locality are listed in the LOCALITY table under the LOCCL_CODE field. Filtering the dataset by selecting only gazetted localities (locality_class_code = 'G') will assist in improving the representation.
The dataset incorporates the best available data and for some layers, not all parts of the country are covered. For example, there are no Local Government Areas in the Australian Capital Territory. Some parts of South Australia and the Australian Capital Territory are not covered by suburbs.
Is the data available in a single national table?
No. You will need to use a database or equivalent process to merge the jurisdiction tables.
Why are the spatial elements separate from the data elements?
The dataset has been modelled in a way to support the widest possible use of the information. The data is intended for use in a GIS application or database that supports spatial functionality.
Are the relationships for database tables available?
You will need to construct the relationships between tables using the Administrative Boundaries Product Description document as a guide.
Can I get help with using Administrative Boundaries?
PSMA resellers provide a range of commercial products based on Administrative Boundaries including software solutions, consultancy and support.
What are Other Territories (OT)?
Boundaries covering external territories such as Christmas Island, Cocos (Keeling) Islands, Jervis Bay or Norfolk Island are considered OT; generally in accordance with the ABS classification of this area.
What coordinates are used to represent the data?
All data sets are represented using geographic coordinates (longitude and latitude) on the Geocentric Datum of Australia (GDA94).
How often is the dataset updated?
PSMA issues four releases of the Administrative Boundaries data set annually.
Are the Electoral Boundaries up-to-date?
The electoral boundary redistribution process typically updates boundaries between elections. Whilst these boundaries can be finalised sometime before an election, they will typically only be adopted at the time of the election. Generally only the active boundaries (those supporting the current Parliament) are included in this theme with updates applied at the most appropriate opportunity.
Australian Bureau of Statistics (ABS) data
Are ABS Collection Districts (CD) and Statistical Local Areas (SLA) shown?
No. Collection Districts (CDs) and Statistical Local Areas (SLAs) were part of the Australian Standard Geographical Classification (ASGC) used by the ABS between 1984 and 2011. More information.
The ASGC was replaced by the Australian Statistical Geography Standard (ASGS) in July 2011.
There is mesh block information for 2006 and 2011. Which one should I use?
It is strongly recommended that the Mesh Blocks 2011 (*_MB_2011) be used as a reference dataset as it is the base geography for the most recent Census and other statistical geographies (ASGS). The 2006 experimental mesh blocks were published for illustrative purposes and to facilitate consultation. They were not formally used to create any ABS statistical products. While total usual residence persons and total dwelling counts were published with the 2006 experimental mesh blocks, these counts were not passed through the full 2006 Census quality assurance process and therefore should also be treated as experimental in nature.
How often is mesh block information updated?
While mesh block information is included in every quarterly release of the Administrative Boundaries dataset, it is only updated every five years around Census time.