Australia’s moving, and our GPS needs to keep up 

Australia is on the move. Literally.

The tectonic plate sitting under Australia, the ‘Australian Plate’, is moving at a rate of approximately seven centimetres each year. To put that in perspective, seven centimetres is about the diameter of your average apple, a seemingly microscopic adjustment when discussing the meanderings of an entire continental plate. However, imagine what effect this subtle change has over time.

The last time Australia’s Global Positioning System (GPS) coordinates were updated was in 1994, and this set is known as GDA94. Since then, your favourite drive-through has moved 1.68 metres to the North-East. A minor amount to the naked eye, but for a machine relying on fixed GPS coordinates for navigation, it could be enough to send a driverless car past the restaurant driveway and into the front door!

Further, as an ever-increasing array of industries and technologies become reliant on accurate satellite positioning, modernising Australia’s positioning and mapping data has become an important and pressing challenge for Government and industries. This is why tackling continental drift is an important and pressing challenge for the Geographic Information System (GIS) community.

Here’s what you need to know about our Global Positioning System and how your position is determined – brace yourself for acronyms from here on.

The Global Positioning System has become ubiquitous, it’s an integral component of most smartphones and built into almost all new cars. But how is your location actually determined?

Individual positions are mapped against a series of coordinates determined by a global reference frame called the International Terrestrial Reference Frame (ITRF). The ITRF that underpins Australia’s reference frame was first implemented in 1992. Since then the ITRF has undergone significant improvements, including allowing centimetre accuracy in real-time.

What is Australia doing?

Like all great things, the partnership between Australia and GDA94 is coming to an end. However, we are getting ready for an upgrade.

Stage 1 (currently underway)

Australia has implemented a new datum (data) standard known as the Geocentric Datum of Australia 2020 (GDA2020). This modernised approach will take advantage of the latest ITRF framework and ensure that all Australians can take advantage of the increased accuracy that current and future positioning and navigation technologies provide.

The first stage is underway with the transition to the GDA2020. The coordinate shift between GDA94 and GDA2020 will be roughly around 1.5 metres in the South Eastern region of Australia and 1.8 metres in Western Australia, which largely accounts for tectonic rotation of the Australian plate from 1994 projected to 2020. We have illustrated this below.

Stage 2 (starting in 2020)

The second stage (commencing in January 2020) will introduce a new datum called Australian Terrestrial Reference Frame (ATRF) but unlike GDA2020 (static datum), the ATRF will account for Australia’s drift dynamically and will maintain alignment with ITRF.

For the GIS community this is a big deal and not without some significant challenges. The 1.68 metre change requires a robust GIS transformation strategy and metadata must be changed, otherwise your autonomous vehicle might still end up missing your favourite drive-through.

Mitigating these challenges and the adoption of the ATRF will in turn bring major benefits. The benefits include improved accuracy for a wider spectrum of people who will use Global Navigation Satellite System (GNSS) precise positioning, but it also mitigates unmodelled errors arising from deformation events such as earthquakes.

How do the changes affect you?

The average Australian probably won’t notice a thing. However, our GPS-enabled devices can take advantage of increased accuracy. Regardless of even the most minor changes in our natural landscape, we can be rest assured that our automated cars can drive us to the precise location we want, automated drones can deliver packages right to our doorstep and our smart watch can tell us the exact track we ran this morning.

Unless of course, some of us prefer erroneous but enhanced running distances.

Saadullah Saddozai
Data Analyst

GWI Senior Consultant Gavin Deeprose

Gavin Deeprose
Consulting Manager

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