Australia Is On The Move
The New 2020 Datum and Map Grid of Australia
Did you know Australia is constantly on the move? The continent is galloping towards the Papua New
Guinea at 7cm a year. We are the fastest moving continent and over 35 million years this means
Australia has effectively moved from Melbourne to Townsville.
Did you also know that your GPS will soon, if not
already, be able to locate positions to an accuracy of
10cm?
These two astounding facts may not directly impact
navigation when in your 4WD (I’m sure that track
intersection should be a metre to the left………..),
however it does mean a new datum and new map grid
have recently been adopted in Australia and you may
come across them, so here’s an overview of the
various coordinate systems and datums in use.
Figure 1: Difference between MGA94 and MGA2020
If you’ve completed the Club navigation course you may remember the two main map grids used on
Australian maps in the last 54 years, namely AMG66 and MGA94 (yes there was also AMG84 but not
for Victoria). If you really paid attention you will know that MGA94 coordinates are about 200m north
east of the AMG66 coordinates.
Now to confuse things a bit further two new systems have recently been introduced, namely
MGA2020, which is a successor to MGA94, and ATRF2014 which can be viewed as Australia’s version
of WGS84, or in other words the GPS coordinate system.
Some Terminology
The first thing to understand is what a geodetic datum is. It is made up of three things
1. the shape used to model the earth. As the earth is not a perfect sphere, but squashed at the
poles, a geoid is used which is a mathematical shape of the Earth;
2. a coordinate system – better known as latitude and longitude;
3. a set of reference points on the Earth’s surface to locate the coordinate system, such as the
zero meridian which is very close but not quite at the Greenwich Observatory in London.