GUIDELINE FOR PLACEMENT OF STANDARD SURVEY
MARKS (SSMs)
The installation of Landgate Standard Survey Marks is to be in accordance with Special Publication No 1
(SP1 v2.1) and the SP1 Guideline for Installation and Documentation of Survey Control Marks. These
Landgate guidelines prevail over the SP1 v2.1 guidelines where there is inconsistency between the two.
1. SITE REQUIREMENTS
The placement of an SSM should be undertaken giving consideration to the following:
1.1
Long-term stability
1.2
Clear sky view, free of potential multi-path and RFI sources
1.3
Ease of access and occupation
1.4
Minimal vegetation clearing (present and future)
1.5
Avoidance of creating an OHS hazard.
It is preferable that the site be selected to avoid any service corridors, and that it be located sufficiently
distant from any potential works to prevent future damage to the mark.
2. PLACEMENT OF SSM
2.1
2.2
2.3
2.4
2.5
2.6
The mark will consist of a Landgate precast SSM or brass plaque set in concrete, constructed in
accordance with the sketches attached. A hatch cover is required in built-up areas or where the
SSM may be at risk, or pose an OHS risk.
The Landgate assigned unique identifier shall be stamped on the brass plaque.
A minimum of three (3) reference marks (RMs) shall be placed, preferably at 120 degree
separation in a safe position at least 0.2 metres below the natural surface and approximately 3
to 5 metres distant. The RMs should be 13mm diameter mild steel rods, of sufficient length to
ensure stability (0.6m preferred) and surrounded by a 0.2m diameter concrete collar of one half
the RM length in depth. If the placement of subsurface marks is impractical alternative types of
RMs (bridge nails in bitumen, nails in wall, etc) are suitable..
Where precast marks cannot be used good quality materials are to be used in the construction
of the SSM and RMs.
Measure and provide the height difference from the mark to ground level and where a hatch
cover has been installed from the hatch cover to ground level.
Place a Landgate witness plate in close proximity to the SSM, either attached to a star iron
picket or a suitable nearby fixture. The distance and bearing to the SSM is to be stamped onto
the witness plate. Where public safety is likely to be an issue, the requirement for a witness
plate can be waived.
3. REFERENCE MARK MEASUREMENT
3.1
3.2
3.3
3.4
3.5
3.6
3.7
All distances between the SSM and RMs, and between RMs must be recorded to three decimal
places.
Bearings from the new SSM to each RM are to be recorded to 20 seconds of arc. The bearings
will be oriented to true azimuth by observing an angle from an adjacent known point. If a known
point is not visible, azimuth should be established by observing to a temporary GNSS station.
Irrespective, compass bearings from the SSM to all RMs must be recorded.
Differences greater than 5mm between measured and calculated distances are unacceptable.
The difference in height between RMs and SSM must be accurately measured (eg spirit level or
total station).
Measure and provide the height difference from the RMs to ground level.
RMs are numbered consecutively clockwise with number 1 being assigned to the first RM as
viewed clockwise from north.
The use of RTK is not acceptable for the measurement of RMs.
STATION SUMMARIES
A sketch of access information and a description of physical characteristics of the SSM and RMs are to
be provided. This should include sufficient access and recovery information and connections to any local
features that will enable the SSM to be readily found.
Appendix 1 Installation of Precast SSM
Appendix 2 Installation of Brass Plaque SSM