Bushwalks and Emergency Services Personnel

Back in the year 2000, the GDA94 datum was implemented in Australia, and Topographic maps produced after that date used the new datum. The previous datum was AGD66 - Australian Geodetic Datum implemented in 1966. The difference between GDA94 and AGD66 was approximately 200 meters, so bushwalkers and rogainers needed to be aware of which datum a map used. Some Australian States produced Topo maps with both datums marked along the edges, and a few handy tips on conversion.

The GDA2020 datum moves all Australian coordinates by approximately 1.8 meters to the North and slightly to the East. Since the thickness of each contour line on a 1:25,000 Topographic map represents around 8 meters on the ground, your navigation won’t be too affected.

Today, when you’re using your GPS you will get an accuracy of close to 5 meters. You GPS is probably set to use the WGS84 (or MGA) datum which is very close to GDA94, and will also be very close to GDA2020. It’s possible that Topo maps will start being produced using the GDA2020 projection as soon as 2017, so do a quick double check anyway when you buy one.

And if you’re keen to know what’s causing this pressing need to move the whole of Australia a couple of meters away from where it was in 1994…..

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