I'm a Surveyor... what does it mean for me ?

As a surveyor you will be aware of datums, and also the need for an Australian datum that is fit for purpose.

GDA2020 is the datum that will replace GDA94… it was adopted in early 2017. All the states will need to coordinate their move to GDA2020

The CORS network will be among the first to make the move - they are ready now. So an action on you today is to make sure your Total Station firmware is updated to handle it…. get onto Leica or Trimble to see if an update is available.

And remember to specify what datum you are using when to send in a sketch plan. Just specifying GDA or MGA is no longer good enough, you will need to state a year - MGA94 or MGA2020. The problem with a 1.8, shift between GDA94 and GDA2020 is that it may not be immediately obvious that there is an error. This is in contrast with the last shift that was around 200m.

And if you use GIS software, be aware of what datum each layer of your map is, you may need to re-project some of them. Your software supplier probably hasn’t set up a projection for GDA2020 yet. However, some software packages allow you to create your own custom projections. Depending on what level of accuracy you require you may be able to just transform your existing 94 datum.

However, it is a little more complicated for those who require sub centimeter precision. Different parts of Australia are moving are different rates, and also distorting slightly. These distortions aren’t large by some standards - the whole continent sits on a single tectonic plate, so we don’t have the issues that New Zealand or US or many other countries have. We don’t experience earthquakes, or plates moving together to form Himalayan scale mountains. Consequently, distortions are limited and fairly localised. However, there is a small amount of natural movement and also a degree of man-made ground movement caused activities such as mining and sub-surface water extraction.

All this seems a fairly poor excuse to cause so much upheaval for surveyors and other GIS professionals. However, there is a fairly good reason for the change, and it all comes down to how technology has changed how surveyors do their job.

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