[background image] image of construction equipment
Choosing a datum

GDA94 or GDA2020?

Use the datum your designs and site control are in. Choose the wrong one and everything is out by about 1.5 metres. If you are not sure, ask whoever supplied the design.

You choose by mountpoint

NEAREST_20 sends GDA2020. NEAREST_94 sends GDA94. Both are included for every rover, and you can change between them in your rover at any time.

Two datums, one ground

Which one is yours?

Both describe the same ground. They differ because Australia has moved since GDA94 was set.

image of commercial construction project

GDA2020: use NEAREST_20

The current national datum. Most new designs are in GDA2020.
image of commercial construction project

GDA94: use NEAREST_94

The earlier datum. Older designs and long-running sites are often still in GDA94.