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Australia is moving two hundred and fifty metres to the north east

While most people will not feel the earth move, census clients may have heard about the change to mapping systems and want to know how it will affect Census mapping products.

In the mid 1990s Australia's mapping agencies agreed to adopt a new Geocentric Datum for Australia (GDA94) and to implement this new model of the earth in their mapping systems by the year 2000. Implementation is slightly behind schedule but some States have changed to the new datum and others will change in the next year.

The adoption of GDA94 will make Australian mapping directly compatible with the Global Positioning System (GPS) which is widely used for professional and recreational navigation. It will mean, however, that the coordinates or latitudes and longitudes of all Australian mapping will change by about 250 metres to the north east.

All ABS spatial data such as the Master Spatial Database (MSD), used for Census Collection District design and mapping, and the Reduced Output Spatial Database (ROSD), used in CDATA96, are currently on the old datum (AGD66). All ABS digital boundary files (CD, SLA, etc) are also on the old datum. The ABS GDA implementation strategy is to convert the MSD to the new datum during 2001 and to make all 2001 Census output products GDA compliant. In the meantime ABS clients are advised that:

• all ABS spatial data is currently AGD66 datum;
  
• 2001 Census output products including CDATA topography and boundaries will be GDA compliant;
  
• Australian Standard Geographical Classification (ASGC) 2001 Edition boundaries will be GDA compliant; and
  
• a new version of ASGC 1996 Edition boundaries will also be created on GDA datum so that they can be directly overlaid with 2001 boundaries.