Australia’s Intergovernmental Committee on Surveying and Mapping (ICSM) is developing a proposal plan to update Australia’s national datum. ICSM’s Permanent Committee on Geodesy (PCG) is currently preparing the documentation for consideration by ANZLIC at their July 2015 meeting for the proposed datum modernisation and its implementation timeframe.

PCG met in Canberra in February 2015 to consider and revise its Datum Modernisation Roadmap, which proposes an incremental, two stage implementation of a two-frame concept in which both a conventional datum and a reference frame will be simultaneously supported.

Stage-1 has been given a working title of Geocentric Datum of Australia 2020 (GDA2020) and Stage-2 has a working title of the Australian Terrestrial Reference Frame (ATRF). The PCG proposal will recommend formal release of all resources required for Stage–1 of the modernised Australian datum by 1 January 2017.

Stage–1 proposes a national adjustment of the geodetic network and the coordinates projected to a reference date of 1 January 2020. Horizontal coordinates will shift by approximately 1.8 metres to align with ITRF, meaning that any difference between ITRF and the new datum will be negligible for most users.

Stage–2 is proposed to commence 1 January 2020 and involves transitioning to the new reference frame, ATRF, which will be time dependent and highly accurate with respect to the ITRF. GDA2020 (or its successor) would also be retained unless it became evident that a static datum was no longer needed.

To view more details of the proposal, visit PCG’s website.

PCG has also drafted a statement on datum modernisation, which outlines the background to GDA94 modernisation, provides a brief synopsis of the drivers for change and describes the new two–frame proposal in more detail.