Glenn Baddeley - GPS Mapping in Australia

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UTM Zones in Australia

Australia is covered by 30 zones in the Universal Transverse Mercator grid system.

Each zone is referred to by:

Within each zone a cartesian coordinate system is used to specify a location in units of metres (or meters if you are from the U.S.A.).

eg. A typical set of fully specified coordinates are E 578315, N 5789240, UTM Zone 54H, Datum GDA94.

This image has been derived from UTM Grid Zones of the World compiled by Alan Morton. This page presents a large map of the world and shows all the UTM zones and explains how they are defined.

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UTM Zones in Victoria

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UTM Datums and Map Grids in Australia

Australia now uses the GDA94 datum (Geocentric Datum of Australia 1994) for latitude / longitude and the MGA94 map grid (Map Grid of Australia 1994) for UTM coordinates. This supercedes the AGD66 (Australian Geodetic Datum 1966) and the AMG66 map grid (Australian Map Grid 1996), and their very similar counterparts AGD84 and AMG84 which were used in some parts of Australia. The change in map grid results in UTM coordinates moving about 100 - 200 metres to the North-East, so it is important to always specify the datum when recording or publishing UTM coordinates.

GDA94 is the same as the WGS84 (World Grid System 1984) for most practical purposes. The differences are of the order of a few centimetres.

For Australian GPS users this means that they should switch the datum / grid on their GPS receivers from AGD66 (Aus Geoid '66) or AGD84 (Aus Geoid '84) to use WGS84, and replace their old topographic maps with new ones which are being updated and published with the new map grid.

See the following links for further explanation, information and tools:

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Copyright © Glenn Baddeley 2005
http://home.pacific.net.au/~gnb/gps/mapping.html was last updated 11 October 2005.
Report problems and send comments to Glenn Baddeley.