Geodetic survey mark information
The WA geodetic system, which consists of geodetic survey marks referenced to Geocentric Datum of Australia 2020, is prescribed as fundamental land information under the Land Information Authority Regulations 2007 (Land Information Authority Act 2006). Landgate, on behalf of the WA government, is the custodian of the geodetic system which carries obligations to provide a geodetic datum as one of the public utility services under the Land Administration Regulations 1998. Landgate maintains this important infrastructure for the benefit of the survey industry and the broader geospatial community. All geodetic marks have been erected and are protected under the Standard Survey Marks Act 1924.
The Geodetic On Line Access (GOLA) database stores the details of approximately 65 000 geodetic marks installed across Western Australia and includes the Christmas and Cocos (Keeling) islands. Geodetic mark report is available for all standard survey marks (SSMs), bench marks (BMs) and continuously operating reference stations (CORS).
Options for accessing geodetic mark information
- Map Viewer Plus (MVP) - provides full information about geodetic survey marks via a popup and links to the GOLA report and station access diagram. Geodetic marks information can be accessed by selecting 'Geodetic' from the MVP layer list. MVP works on most popular devices including mobile devices and has search options available to enable the location of marks. For details download this Map Viewer Plus - How to guide [PDF 1.0MB] or watch this how to video.
- Locate - provides full information about geodetic survey marks via a popup and links to the GOLA report and station access diagram. Select the Geodetic Survey Marks (LGATE-076) layer under the Locate Property and Planning (Locate - How to guide) [PDF 0.7MB]. Geodetic survey network observations (LGATE-261) are also available. Further information about Locate can be found here.
- Data.wa.gov.au - the open data portal provides the geodetic data (Geodetic Survey Marks (LGATE-076), Reference marks (LGATE-099) and Geodetic Survey Network Observations (LGATE-261)) in the form of a downloadable Shapefile or WMS access to the Landgate geodetic layer.
- Download a Google Earth KML file [KML 4KB] and open the link which will automatically download the current version of KML with all Western Australia’s geodetic marks directly to your Google Earth application. Note it takes time to download the complete file [approx. 2MB]. Once in Google Earth zoom to your area of interest to view geodetic marks. Selecting a geodetic mark symbol opens a popup with some basic attributes and links to a complete GOLA station report and access diagram. For details watch this how to video.
Geodetic mark report information
- Horizontal datum - geographic coordinates in GDA2020 and GDA94, UTM projected coordinates in MGA2020 and MGA94 and TM project grids where available. Other historic datums are available on request.
- Note - Currently GDA2020 is the primary horizontal datum and the only datum being maintained and GDA94 is now considered as a historic datum
- GDA2020 Technical Manual [PDF 3.08MB]
- GDA94 Technical Manual [PDF 2.18]
- Vertical datum - heights in AHD71, Christmas and Cocos (Keeling) height datums.
- For additional information about AHD71 modification around Perth please refer to this document [PDF 0.9MB] (Metro and Buffer Zones can be downloaded here [KML 0.5MB])
- GDA2020 ellipsoidal heights provided on GNSS surveyed marks. Derived GDA94 and GDA2020 ellipsoidal heights provided on all marks.
- The Australian Vertical Working Surface (AVWS) heights are not provided in this report but can easily be computed from GDA2020 ellipsoidal height. For more information on how to obtain AVWS heights refer to the section below.
- Geoid (N) values for AUSGeoid2020 and AUSGeoid09.
- AUSGeoid2020 product files
- AUSGeoids Calculators
- Important note: AUSGeoid2020 is not compatible with GDA94.
- Positional uncertainty (horizontal and vertical), relative horizontal accuracy, and error ellipses.
- Survey method.
- Reference mark information.
- Physical status and date of the mark (and reference marks).
- Cadastral connection, field books, and other notes.
- Station summary access diagram.
- Sample geodetic report [PDF 0.03MB]
- Sample station summary diagram [PDF 0.2MB]
Australian Vertical Working Surface
The Australian Vertical Working Surface (AVWS) is a new reference surface for heights in Australia and an alternative to AHD. AVWS is based on Australian Gravimetric Quasigeoid (AGQG) model and can be computed directly from GNSS without needing to connect to any survey mark with accuracy of 4-8 cm. Geoscience Australia has developed a tool that can transform between ellipsoidal and AWVS heights. To compute AVWS in your software the quasigeoid model is also available for download.
Accessing CORS data
CORS located in WA are operated and maintained by Geoscience Australia. For CORS operation related enquiries contact the GNSS Network Operations Centre Duty Officer on +61 (0) 2 6249 9004 or email email@example.com. CORS data can be accessed from https://data.gnss.ga.gov.au/. Geodetic mark reports for WA CORS are available via GOLA.
Update geodetic mark status
When a geodetic mark (SSM or BM) is used (for any reason other than a cadastral survey which requires a field book to be lodged) Map Viewer Plus should be used to report feedback about the condition of the mark. This information is used to keep the geodetic database up to date for the benefit of all geodetic mark users. You can also provide mark feedback via geodetic mark status report form [PDF 0.6MB] and email it to firstname.lastname@example.org.
Geodetic mark impending works notification
Where any geodetic mark is at risk of being damaged or destroyed, Landgate must be notified immediately to enable appropriate remedial action.The Geodetic mark impending works notification form [PDF 0.5MB] should be used in these circumstances or alternatively you can contact a member of the survey services team at email@example.com or phone +61 (0) 8 9273 7111.
Asbestos in geodetic mark hatch cover surrounds
A number of Landgate's early geodetic mark hatch cover surrounds were moulded using asbestos cement. Please read this asbestos notification before using geodetic marks [PDF 0.3MB].
Subscribe to our Geodetic Newsletter to stay up to date with the latest information from Landgate's Survey Services department.
For more information contact a member of the Survey Services team on +61 (0) 8 9273 7111 or email firstname.lastname@example.org.