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Surveyor-General’s DirectionNo. 5Calibration of Electronic Distance Measuring(EDM) Equipment

Title: Surveyor-General’s Direction No. 5Calibration of Electronic Distance Measuring (EDM) EquipmentPublished bySpatial ServicesA Unit of the Department of Customer Service346 Panorama AvenueBATHURST NSW 2795Tel: (02) 6332 8287www.spatial.nsw.gov.auCover photograph shows Lethbridge Park EDM BaselineEnquiriesAny enquiries regarding this Direction should be forwarded toCustomer Support - EDM Calibration & Baseline Booking SystemFor access to legislation in force in NSW go to the official NSW Government website for onlinepublication of legislation at www.legislation.nsw.gov.au.Copyright Crown in right of New South Wales through Spatial Services, a division of theDepartment of Customer Service (DCS Spatial Services), 2019.This copyright work is licensed under a Creative Commons Australia Attribution 4.0 licence.Spatial Services (B) P19/10/038II

Document Control SheetRecord of Document IssuesVersion No. Issue Date1.0November 19931.1August 19971.2January 19992.0March 20002.1December 20092.23.0June 2016July 2019Nature of AmendmentInitial ReleaseMinor RevisionMinor RevisionMinor RevisionMinor Revision - Surveying and Spatial InformationRegulation 2006Minor RevisionMajor Revision - Surveying and Spatial InformationRegulation 2017, removal of survey measuringbands, update of EDM calibration infrastructure andprocessesDocument Approval:Approved By:Narelle UnderwoodSurveyor-General of NSWDate of Approval: July 2019III

Surveyor-General’s Direction No.5 – Calibration of Electronic Distance Measuring (EDM) Equipment - Version 3.0 July 2019Contents1.Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.12.Background and Definitions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22.1 Description of EDM Baseline Facilities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22.2 Access to EDM Baselines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22.3 Verification of EDM Baselines by the Surveyor-General. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22.4 Calibration of EDM Equipment by the Surveyor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32.4.1 Preparation of the Equipment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32.4.2 Observation Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32.4.3 Data Recording. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62.4.4 Data Processing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62.4.5 Analysis of the Calibration Results and Application of Instrument Corrections. . . . . . . . . . . 93.Conclusion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114.Acronyms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115.References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126.Appendices. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136.1 Schedule of EDM Baselines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136.2 Change in Pressure (Millibars) Corresponding to Change in Height of 10 Geopotential Metres.14IV

Surveyor-General’s Direction No.5 – Calibration of Electronic Distance Measuring (EDM) Equipment - Version 3.0 July 20191. IntroductionThe Surveyor-General, as a verifying authority for Reference Standards of Measurement, Length,provides the infrastructure for surveyors to verify their Electronic Distance Measuring (EDM) equipmentin accordance with the National Measurement Act 1960. Consequently, surveyors are required by theSurveying and Spatial Information Regulation 2017, Clause 14, to verify their measuring equipment inrelation to an Australian or State Primary Standard of measurement of length, and thereby achieve legaltraceability of length.It should be noted that Legal Traceability of length measurement is not confined to cadastral surveys,as any length measurement stated by a surveyor could be subject to dispute and subsequent litigation.This direction outlines the facilities maintained for the verification of EDM equipment and theprocedures required to comply with the Surveying and Spatial Information Regulation 2017.1.1Background and DefinitionsThe National Measurement Act 1960 establishes the legislative framework for a national system ofstandards and prescribes the legal measurement units for all physical quantities. Length measurement,while being a fundamental element of survey work, is only one of more than thirty physical quantitiescovered by the Act.The National Measurement Act 1960 is administered by the National Measurement Institute (NMI) whichmay in turn appoint organisations as a Verifying Authority under the provisions of Clause 73 of theNational Measurement Act 1960. The Surveyor-General of NSW has been so appointed.The appointment of the Surveyor-General as a Verifying Authority is reviewed every eighteen months.The review consists of an audit of the quality management system and procedures against AS ISO/IEC17025 and is undertaken by the National Association of Testing Authorities (NATA) and NMI.Legal Traceability of length measurement refers to the legal hierarchy of measurement standardstraceable through an unbroken chain of verifications from the most precise standard (e.g. NationalStandard) down through the subsidiary standards to the working standard, being the surveyor’s EDMinstrument. In particular the National Measurement Act 1960, Section 10, requires that all measurementsof physical quantities are to be ascertained in accordance with appropriate Australian or Statestandards of measurement. Consequently, the requirements of the National Measurement Act 1960which are relevant to surveyors are incorporated in the Surveying and Spatial Information Regulation2017.Precision is generally defined as the repeatability of readings as displayed by measuring equipment,or the internal consistency of a measuring procedure, and would usually be quantified in terms of thestandard deviation or uncertainty of a set of observations.Accuracy is the closeness of the measured value to the true’ value.The Surveying and Spatial Information Regulation 2017, Clause 24 requires that both the accuracy of thecalibration and the field measuring technique is to be such that any length measurement made with theequipment will achieve an accuracy of 10mm 50ppm or better at a confidence interval of 95%.Surveyors have generally used the traverse closure as an indicator of survey accuracy, however this isonly a measure of internal consistency or precision.Verification is a test to confirm that the accuracy attained by a measuring instrument is withinallowable accuracy limits as defined in a specification or as required by legislation.1

Surveyor-General’s Direction No.5 – Calibration of Electronic Distance Measuring (EDM) Equipment - Version 3.0 July 2019Calibration is the determination of instrument errors by comparing the value indicated by themeasuring equipment with the known or true value. Consequently corrections must be applied to allmeasurements made with the equipment in order to obtain true’ measurements.2. ProceduresThe Surveying and Spatial Information Regulation 2017, Clause 14 requires surveyors to verify their EDMequipment in relation to the State primary standard of measurement of length at least once every yearand immediately after service or repair.2.1Description of EDM Baseline FacilitiesCommencing in the early 1980s a total of eighteen EDM testlines were established throughout NSW toenable the calibration of EDM equipment of that era. The Office of the Surveyor-General continues toupgrade the original 4-pillar “Testline” facilities to six or seven pillar Baselines to provide an increasedaccuracy for the calibration of EDM equipment. Four of the original 4-pillar facilities continue to bemaintained until they are either upgraded or replaced with a 7-pillar facility.Note, any reference in this direction to EDM Baseline also refers to EDM Testline.The Surveyor-General currently maintains twelve concrete pillared EDM baselines throughout NSW(Schedule of EDM Baselines).The NSW baselines use the Heerbrugg (Schwendener) design which enables the computation of theadditive constant without reference to the published inter-pillar distances, therefore avoiding the effectthat pillar movement can have on the computation of the additive constant.Each pillar contains a stainless steel plate with a 5/8” Whitworth screwed spigot to receive the tribrach.The spigot is protected by a PVC cap secured by three bolts which require the use of a 3/8inch or10mm Allen key for their removal. The PVC caps and bolts must be replace securely to minimisedamage caused by vandalism. Damaged or missing caps and bolts should be reported immediately toCustomer Support, so repairs can be undertaken promptly.2.2Access to EDM BaselinesUse of all baselines is provided free of charge for the calibration of EDM equipment and access to allEDM baselines must be booked using the online EDM Baseline Booking System.2.3Verification of EDM Baselines by the Surveyor-GeneralEDM baselines are currently verified using a Leica TS30 EDM instrument. This instrument has anaccuracy specification of (0.6mm 1ppm) and is verified annually by the National MeasurementInstitute (NMI) Lindfield, and issued a Regulation 13 Certificate, as a Reference Standard ofmeasurement.Each of the EDM baselines is re-verified within a two-year period in accordance with NMIrecommendations.2