Datum Modernisation in Australia

Nothing on the surface of the Earth is fixed. The Earth's tectonic plates are constantly moving - in different directions and at different speeds. The Australian plate is moving in a north-easterly direction at a rate of about 7cm per year, or about 5mm per month.

This means the latitude and longitude of points in Australia are changing. Coordinates are calculated using a set of defined reference points called a geodetic datum. The current Australian datum, the Geocentric Datum of Australia 1994 (GDA94), is now over 20 years old.

We have moved approximately 1.6m since 1994, and Australia's coordinates are no longer accurate or in alignment with global navigation satellites systems (GNSS) such as GPS, which use the reference frame, WGS84. This becomes highly significant when it comes to the use of applications that rely on accurate satellite positioning such as in-vehicle navigation; smartphones; automated mining operations; precision agriculture; and surveying where high absolute accuracies are required. To address this, Australia is implementing a new datum that will be known as the Geocentric Datum of Australia 2020 (GDA2020).

The Intergovernmental Committee on Surveying and Mapping (ICSM) is responsible for modernising Australia's Datum to ensure that all Australians can take advantage of the increased accuracy that current and future positioning and navigation technologies provide. The ICSM formed a dedicated working group, the GDA Modernisation Implementation Working Group, to oversee the implementation of the modernised datum across Australia's government, academic and industry sectors.

Geoscience Australia is the peak science agency responsible for technical development and maintenance of the national geodetic datum, and will update the coordinates of reference points that define Australia's new national datum, GDA2020. Geoscience Australia will also be assisting Australian Government agencies and Spatial Software providers to adopt the new datum.

Please note that there are limitations in using WGS84 in Australia.

Datum Modernisation is required due to the significant growth in the number of users of precise positioning and the expected improvement in positioning technology over the coming decade. The change is particularly relevant to the surveying, spatial sciences and mapping industries.

Australia's datum will be modernised in a two stage approach to ensure that Australians continue to have access to the most accurate location. The first stage, the Geocentric Datum of Australia 2020 (GDA2020), will be released in early 2017. GDA2020 will be based on the projected position of the Australian continent in 2020 according to the global standard, the International Terrestrial Reference Frame (ITRF). This datum will be fixed to the Australian continent, where coordinates do not change with time. As a consequence, in 2017 coordinates from global navigation satellites systems (GNSS) such as GPS, which are based on WGS84/ITRF will be approximately 20cm offset from GDA2020 in 2017; however, this gap will slowly close by 2020 as GNSS coordinates move towards GDA2020.

Stage 2 will commence in January 2020, when users will be able to transition to a time dependant reference frame. This datum will be called the The Australian Terrestrial Reference Frame (ATRF) and will provide the Australian community with a sustainable, traceable, high-precision geodetic reference system capable of meeting the most demanding positioning requirements. This datum will be fixed to the earth, and will model the locations of reference points and their movement over time by maintaining full alignment to ITRF.

Users in State and Territory governments, academic and industry sectors should contact the Intergovernmental Committee on Surveying and Mapping (ICSM) for implementation assistance.

To support the transition of spatial software providers and Australian Government agencies to the new datum, Geoscience Australia is developing a range of tools and technical resources. The first of these will be available in December 2016, with other tools available from early 2017. This includes a web service and software to support transformation of existing datasets from GDA94 to GDA2020. Refer to the Information for Spatial Software Providers tab for further details.

Australian Government agencies that generate or manage spatial information will need to accommodate the forthcoming changes to the national geodetic datum. Geoscience Australia will work with agencies to ensure seamless implementation of the new datum and with minimal disruption to existing systems and processes.

Geoscience Australia will work with your organisation to identify how the implementation can be incorporated into your data supply chain, and at which stage you should transition your spatial datasets. We will provide Australian Government stakeholders with the information and technical assistance required to transition to a modernised datum. For those agencies that require more accurate positioning data for their applications, Geoscience Australia will assist with providing the required transformation tools.

Transitioning to GDA2020 is not mandatory; however Australian Government agencies are strongly encouraged to transition their spatial data as early as possible. This will ensure datasets are consistent across government and are compatible with current and future positioning and navigation technologies.

The initial impact of the datum change will be greatest for existing spatial datasets and precise positioning systems with coordinate uncertainties of less than 3m. Datasets with greater uncertainties may generally only require a change to their metadata.

Geoscience Australia is developing a range of tools and technical resources to support your agency's transition to the new datum including a web service and software to support transformation of existing datasets from GDA94 to GDA2020. The first of these will be available in December 2016, with other tools available from early 2017. These support tools will be available for download via the Information for Spatial Software Providers tab.

For further information contact: geodesy@ga.gov.au.

For details on implementation within Australia's States and Territories and their respective plans on datum modernisation, please refer to the Intergovernmental Committee on Surveying and Mapping (ICSM) webpage.

GDA2020 will be available to adopt from early 2017, and geospatial software providers are strongly encouraged to adopt GDA2020 as early as possible. Early adoption by you will provide users the confidence of knowing that their software provider has adopted the datum modernisation for their data.

Geoscience Australia is developing a range of tools and technical resources to support your organisation's to transition to the new datum including a web service and software to support transformation of existing datasets from GDA94 to GDA2020. For those organisations that require more accurate positioning data for their applications, Geoscience Australia will assist with providing the required reference parameters.

Tools and software available, includes:

  1. Finalising the new ICSM GDA2020 Technical Manual that will have information on the two transformation datasets needed by the spatial information industry—the 7 transformation parameters that define the 3 shifts, 3 rotations and the scale change; and the distortion grid needed for more accurate transformations.
  2. Updating the offline software used to support transformations.
  3. The development of a new online web service that can be used to upload files to transform to GDA2020.

Geoscience Australia is currently building a suite of test data with preliminary transformation parameters that you can use to begin some of your development work.

Geoscience Australia has been working with the European Petroleum Survey Group (EPSG) of the International Association of Oil and Gas Producers to define the EPSG geodetic codes for GDA2020, and these codes are available in the GDA2020 technical specifications tab.

The Australian Terrestrial Reference Frame (ATRF) will commence implementation in January 2020. ATRF realisations will be Earth-fixed and highly accurate with respect to the International Terrestrial Reference Frame (ITRF)and WGS84 reference frame realisations utilised by GNSS, meaning Australian spatial information and GNSS measurements will be directly interoperable.

Official transformation parameters and tools to convert between GDA94 and GDA2020 and vice-versa have been developed by the Intergovernmental Committee on Surveying and Mapping (ICSM), led by Geoscience Australia in conjunction with other jurisdictions and the Cooperative Research Centre—Spatial Information.

This includes:

  • A 2D transformation and distortion grid file in the widely used Canadian National Transformations version 2 (NTv2) format
  • 7 parameter (Helmet) transformation
  • A 3D transformation grid file—format yet to be determined.
  • Values supporting conversion of datasets between GDA2020 and ITRF2014 utilising either a plate motion model or 14 parameter transformation will also be published.

These transformation details will be provided directly to the EPSG Geodetic Parameter Registry which is referred to by spatial software and hardware providers worldwide before incorporating transformation parameters into software and firmware.

The Intergovernmental Committee on Surveying and Mapping (ICSM) has released information to aid in the uptake of the Geocentric Datum of Australia 2020 (GDA2020) and provide time for software developers to update and test their software before GDA2020 is officially released. To download a copy, please click here.

Datum:

Geocentric Datum of Australia 2020 (GDA2020)

Geographical coordinate set:
(latitude, longitude)

Geocentric Datum of Australia 2020 (GDA2020)

Grid coordinates:
(eastings, northings, zone)

(Universal Transverse Mercator, using the GRS80 ellipsoid)
Map Grid of Australia 2020 (MGA2020)

Reference Frame:

ITRF2014 (International Terrestrial Reference Frame 2014)

Ellipsoid:

GRS80

Semi-major axis (a):

6,378,137 metres

Inverse flattening (1/f):

298.257222101

Epoch:

2020.0

EPSG CRS code

EPSG name

Type

Area Description

1168

Geocentric Datum of Australia 2020

GeodeticDatum

Australia including Lord Howe Island, Macquarie Islands, Ashmore and Cartier Islands, Christmas Island, Cocos (Keeling) Islands, Norfolk Island. All onshore and offshore.

7842

GDA2020

GeodeticCRS (geocentric)

Australia including Lord Howe Island, Macquarie Islands, Ashmore and Cartier Islands, Christmas Island, Cocos (Keeling) Islands, Norfolk Island. All onshore and offshore.

7843

GDA2020

GeodeticCRS (geographic 3D)

Australia including Lord Howe Island, Macquarie Islands, Ashmore and Cartier Islands, Christmas Island, Cocos (Keeling) Islands, Norfolk Island. All onshore and offshore.

7844

GDA2020

GeodeticCRS (geographic 2D)

Australia including Lord Howe Island, Macquarie Islands, Ashmore and Cartier Islands, Christmas Island, Cocos (Keeling) Islands, Norfolk Island. All onshore and offshore.

7845

GDA2020 / GA LCC

ProjectedCRS

Australia - Australian Capital Territory; New South Wales; Northern Territory; Queensland; South Australia; Tasmania; Western Australia; Victoria.

7846

GDA2020 / MGA zone 46

ProjectedCRS

Cocos (Keeling) Islands - offshore west of 96°E.

7847

GDA2020 / MGA zone 47

ProjectedCRS

Cocos (Keeling) Islands - onshore and offshore east of 96°E.

7848

GDA2020 / MGA zone 48

ProjectedCRS

Australia - offshore west of 108°E. Christmas Island - onshore and offshore west of 108°E.

7849

GDA2020 / MGA zone 49

ProjectedCRS

Australia - onshore and offshore west of 114°E. Christmas Island - offshore east of 108°E.

7850

GDA2020 / MGA zone 50

ProjectedCRS

Australia - onshore and offshore between 114°E and 120°E.

7851

GDA2020 / MGA zone 51

ProjectedCRS

Australia - onshore and offshore between 120°E and 126°E.

7852

GDA2020 / MGA zone 52

ProjectedCRS

Australia - onshore and offshore between 126°E and 132°E.

7853

GDA2020 / MGA zone 53

ProjectedCRS

Australia - onshore and offshore between 132°E and 138°E.

7854

GDA2020 / MGA zone 54

ProjectedCRS

Australia - onshore and offshore between 138°E and 144°E.

7855

GDA2020 / MGA zone 55

ProjectedCRS

Australia - onshore and offshore between 144°E and 150°E.

7856

GDA2020 / MGA zone 56

ProjectedCRS

Australia - onshore and offshore between 150°E and 156°E.

7857

GDA2020 / MGA zone 57

ProjectedCRS

Australia including Lord Howe Island and Macquarie Islands - onshore and offshore between 156°E and 162°E.

7858

GDA2020 / MGA zone 58

ProjectedCRS

Australia - offshore east of 162°E. Norfolk Island - onshore and offshore west of 168°E.

7859

GDA2020 / MGA zone 59

ProjectedCRS

Norfolk Island - offshore east of 168°E.

7899

GDA2020 / Vicgrid

ProjectedCRS

Australia - Victoria.

8013

GDA2020 / ALB2020

ProjectedCRS

Australia - Western Australia - Albany area onshore below 190m AHD.

8014

GDA2020 / BIO2020

ProjectedCRS

Australia - Western Australia - Barrow Island and Onslow area onshore.

8015

GDA2020 / BRO2020

ProjectedCRS

Australia - Western Australia - Broome area onshore below 130m AHD.

8016

GDA2020 / BCG2020

ProjectedCRS

Australia - Western Australia - Busselton area onshore below 250m AHD.

8017

GDA2020 / CARN2020

ProjectedCRS

Australia - Western Australia - Carnarvon area onshore.

8018

GDA2020 / CIG2020

ProjectedCRS

Christmas Island - onshore.

8019

GDA2020 / CKIG2020

ProjectedCRS

Cocos (Keeling) Islands - onshore.

8020

GDA2020 / COL2020

ProjectedCRS

Australia - Western Australia - Collie area between 50m and 310m AHD.

8021

GDA2020 / ESP2020

ProjectedCRS

Australia - Western Australia - Esperance area onshore.

8022

GDA2020 / EXM2020

ProjectedCRS

Australia - Western Australia - Exmouth area onshore below 160m AHD.

8023

GDA2020 / GCG2020

ProjectedCRS

Australia - Western Australia - Geraldton area onshore below 195m AHD.

8024

GDA2020 / GOLD2020

ProjectedCRS

Australia - Western Australia - Kalgoorlie area.

8025

GDA2020 / JCG2020

ProjectedCRS

Australia - Western Australia - Jurien Bay area onshore below 200m AHD.

8026

GDA2020 / KALB2020

ProjectedCRS

Australia - Western Australia - Kalbarri area onshore.

8027

GDA2020 / KAR2020

ProjectedCRS

Australia - Western Australia - Karratha area onshore.

8028

GDA2020 / KUN2020

ProjectedCRS

Australia - Western Australia - Kununurra area onshore below 200m AHD.

8029

GDA2020 / LCG2020

ProjectedCRS

Australia - Western Australia - Lancelin area onshore below 200m AHD.

8030

GDA2020 / MRCG2020

ProjectedCRS

Australia - Western Australia - Margaret River area onshore below 200m AHD.

8031

GDA2020 / PCG2020

ProjectedCRS

Australia - Western Australia - Perth area onshore below 165m AHD.

8032

GDA2020 / PHG2020

ProjectedCRS

Australia - Western Australia - Port Hedland area onshore.

For more details on the EPSG Geodetic Parameter Registry, please see www.epsg.org.

If further assistance is required, please contact: geodesy@ga.gov.au.