Survey Instrumentation

Document No:  D12#434750
 
Revision:  3A
 
Date amended:  14-May-2015
The information below is intended to reflect the preferred practice of Main Roads Western Australia ("Main Roads"). Main Roads reserves the right to update this information at any time without notice. If you have any questions or comments please contact Greg Myers by e-mail or on ph (08) 9323-4667.

To the extent permitted by law, Main Roads, its employees, agents, authors and contributors are not liable for any loss resulting from any action taken or reliance made by you on the information herein displayed.

 

Revision Register

 

Ed/Version Number Clause Number Description of Revision Date
1 All Complete conversion to Guideline to incorporate work instruction. 19-Feb-2009
​2 ​All ​Survey Instrumentation revised and updated ​04-Feb-2013
​3 ​All Changes from 3rd order to differential ​12-Feb-2014
​3A​Header​Guideline introduction amended​14-May-2015

Table of Content




1 GENERAL

Mainroads WA through both its inhouse survey capacity and survey suppliers, undertakes a variety of surveys that have varying degrees of accuracy requirements. It is the responsibility of the Consulting Surveyors to use and determine instrumentation relevant to the accuracies required for their surveys. It is therefore the responsibility of the Consulting Surveyor to ensure that the survey instrument being used to perform the work is in working order and within its specified calibration ranges.

This guide for Mainroads WA survey equipment custodians, provides examples of typical modern Instrument Specifications which could be used as a basis for contract audit, checking or preparation. The use of instrumentation appropriate to the task is an important contract function that should be monitored by Mainroads Project Managers.

The procurement,registration,maintenance and disposal of survey instrumentation for Mainroads is the responsibility of the asset custodian in their respective Region.

The Surveying and Geospatial Services branch will continue to provide technical advice and support to the organisation in regards to instrument calibration and testing, purchase and loan requirements, and storage and handling responsibilities.

Refer to Surveying and Geospatial Services 67-08-43 "Digital Ground Survey" for the class of survey accuracy requirements and also 67-08-107 being the "Guideline for Settlement Monitoring Surveys" for accuracies and minimum Instrument capabilities required to achieve the survey outcomes.
 


2 FIXED ASSET MANAGEMENT( SURVEY INSTRUMENTATION)

It is the responsibility of the Senior Engineering Surveyor to register and maintain details for the following survey instruments and equipment as part of the Fixed Asset System for the Surveying and Geospatial Services Branch:

  • Total Stations
  • Traverse Kits 
  • GPS systems
  • Ruggedised Computer
  • Survey Levels
  • Calibrated Measuring Bands
  • Differential Levelling Staves
  • Tribrachs, Optical Plummets

The Fixed Asset records should include the following details:

  • Instrument type or other description
  • Model Number
  • Serial Number
  • Main Roads Fixed Asset Number
  • Purchase Price.

Additional records to be maintained on file for each respective instrument should include any service details and Calibration data where appropriate and include:

  • Date last serviced
  • Service cost and details
  • Date calibrated
  • Calibration values
  • Calibration reports/certificates

 

Minor survey equipment (

 

It is the task of each Responsibility Area to allocate an officer to manage Survey instruments within their Region.



3 CALIBRATION, TESTING AND ADJUSTMENT

It is the responsibility of the Senior Engineering Surveyor to maintain calibration records for the following survey instruments and equipment for the Surveying and Geospatial Services Branch (see above).

The nominated Asset Manager will monitor all arrangements for the instruments and equipment that are to be calibrated or tested in their respective fixed asset organisation.

The calibration, testing and adjustment of the survey instruments should be undertaken by Mainroads Surveying and Geospatial Services staff, a third party certified survey company or a licensed distributor, details of whom are available from the Senior Engineering Surveyor.

Refer to Appendix A for a summary of typical testing and adjustment procedures, which is relevant to this Guideline.

As a guide, the schedule below illustrates the frequency that instrument calibration, testing and adjustment should occur.

Type of Instrument

Calibration and
Testing Periods

Location of Calibration
or Test

Total Station 
Monthly with regular use
Biannual Calibration
Appropriate Servicing 
Field Test-by Surveyor
Curtin Baseline
Manufacturer
GPS Systems  Annual  Calibration
Appropriate Servicing 
Curtin GPS/GNSS Baseline
Manufacturer
Theodolite or
Electronic Theodolite 
Annual
Appropriate Servicing 
Field Test
Manufacturer
Survey Level or
Electronic Level 
As shown at Appendix A
Minimum weekly test
Appropriate Servicing 
Field Test-Surveyor
Field Test - Surveyor
Manufacturer
Calibrated Survey
Measuring Band 
Initial Calibration then annual  Manufacturer/Landgate
Differential Levelling Staves  Annual Calibration 
Landgate
Tribrachs,
Optical Plummets 
Monthly
Biannual Test 
Field Test-Surveyor
Field Test-Surveyor
Levelling Staves, Poles,
Survey Bands and Tapes  
Monthly 
Field Test-Surveyor


3.1 Servicing or repair

Instrumentation requiring servicing should be forwarded, with its accessories, to the relevant manufacturer or licensed distributor. The manufacturer should provide a report on all servicing and repair details. The Senior Engineering Surveyor can supply details of the most suitable distributor for for specific instrumentation.

3.2 Purchase of survey equipment

The purchase of all major survey instruments and equipment is the responsibility of the asset custodian in each respective fixed asset organisational structure. Advice regarding the latest specifications of all major items of survey equipment is available from the Senior Engineering Surveyor. These specifications are to be used to ensure purchased instruments have the capability, expected accuracy and range required for its intended use.

3.3 Loan of survey equipment

A limited number of survey levels and total stations have been retained within the Surveying and Geospatial Services Branch at DAC for temporary loan purposes. All requests for the temporary loan of instrumentation shall be made in writing to the Senior Engineering Surveyor.

3.4 Disposal of survey equipment

The disposal of all major survey instruments and equipment is the responsibility of the asset custodian in each respective fixed asset organisational structure. The Senior Engineering Surveyor is available to provide assistance in regards to organising instrument appraisals.



4 TYPICAL SURVEY INSTRUMENT SPECIFICATION FOR MAINROADS PROJECTS

The following information is provided as a guide to show details of typical modern Instruments which Contractors may use on Mainroads contracts.There are now too many Instuments available in the marketplace to list individually so the following is only a sample. Note that "reflector-less" instruments which use a laser beam to measure to remote objects or surfaces are now widely available but these have a limited measuring range and reduced accuracy on flat surfaces at the same height as the Instrument. The Senior Engineering Surveyor can provide some details on these Instruments if requested.


4.1 Robotic Total Station

This instrument would be used for high accuracy surveys such as Bridge Construction or Monitoring and may have refletorless capabilities built in. The instrument could also be used for Digital Ground Surveys.

Theodolite
  Angle Measurement
Dual circle Observations (reads both sides of circles)
  Minimum reading  
Horizontal
Vertical 
1"
1"
  Standard Deviation (either)    2.0"
  Motorisation    
 

Positioning Accuracy    
Rotation Speed 

  0.5 mgon
50 gon/sec
   Operation Mode
 

Fully Robotic 

 

Clamp free manual mode
Lock and Auto tracking (Auto Target  Recognition)
Remote Control (one-man)
Telescope                 
Magnification                      30x or better
Image Erect  
Minimum Focus      1.7m
Distance Meter
  Normal & Repeat Measurement             
  Accuracy / Standard Deviation   + (2mm + 2ppm)
  Measuring Time   3 sec
     
  Tracking Measurement  
  Accuracy / Standard Deviation   + (5mm + 2ppm)
  Measuring Time   0.3 sec
       
  Range    
  1 to 3 prisms (Average Conditions)   2.5 km / 3.5 km
Recording
 

Hardware   

 

 PCMCIA Memory Card or built in memory chip
Internal Memory (for programs)
RS232 or Bluetooth Interface
  0.5 mb card -       (4000 data blocks)    7000 pts
  1.0 mb card -   14000 pts
  2.0 mb card -       30000 pts
​ 
Data Transfer
​1. Total Station > PCMCIA Card > PC
2. RS232 Interface or Bluetooth
  Raw Data

Raw data must be compatible with 12D and/or
MOSS software and customised to accommodate
Main Roads current procedures.
   Note : PC = IBM Pentium PC or equivalent (running Windows XP or later).

Prisms     

360 degrees (capable of being observed from all directions)
Automatic Correction  Line of sight error / Vertical Index Error; Standing Axis Tilt; Earth Curvature & Refraction; Circle Eccentricity; Tilting Axis Error.
Internal Programs 

Tie Distance; Remote Heights; Hidden Points; Set-out; Resection / Freestationing (Least Square Adjusted); Orientation; Reference line; Traversing; Road construction (Alignments Horizontal and vertical); Auditing / surface analysis.
General
  Power Supply
  Built in rechargeable x 2 4.0hr life minimum
  (one in unit + one spare)
  Heavy Duty rechargeable x 1 14hr life minimum
  Rapid Charger   Single unit to charge both power
supplies preferred
  Car battery Adapter x 1 12 Volt source
Warranty  ​Two year on electronics and batteries preferred.
Maintenance Contract
​Period ​5 years
​Basis ​Annual Fee


4.2 Total Station-fully manual operation

This Instrument would be used for high accuracy surveys such as Bridge Construction or Monitoring and may have reflectorless capabilities built in.The instrument could also be used for Digital Ground Surveys.

Theodolite
Angle Measurement  
Minimum reading

Horizontal

Vertical

1"

1"

Standard Deviation (either)   1.5"
Angle Measurement Horizontal 1"
Magnification  30x or better  
Image Erect
Minimum Focus 1.7m  
Distance Meter
Range (for visibility 15 km)  1800m to 1 prism 
  2500m to 3 prisms
  3300m to 9 prisms
 Accuracy + (3mm + 2ppm)
 Measuring Time  (measure mode) first reading 5 sec
  (track mode) better than 1 sec
     
Memory card/module
Capacity                       Capable of storing 6000 points in User Definable Format.
Remark/text storage option preferred.
Options shall be detailed (number of cards, etc).
Data Input/Output  

1. Direct from Total Station via RS232C or Bluetooth interface.

2. Stand-alone 'Card to PC' interface module.

​Note: Both of the above to IBM PC or equivalent (running Windows XP or later).
General
Power Supply  
Built in rechargeable x 2 1.5hr life minimum
(one in unit + one spare)  
Heavy Duty rechargeable  7hr life minimum
Rapid Charger   Single unit to charge both power 
supplies preferred
Car battery Adapter  12 Volt source
Warranty  Two year on electronics and batteries preferred
Maintenance Contract
​Period ​5 years
​Basis ​Annual Fee

 

5 TYPICAL SPECIFICATION FOR LEVELS


5.1 Surveyor's Level

These levels would typically be used for minor works and 3rd Order levelling.

Type    Automatic
Image    Erect
Objective Aperture     Greater than or equal to 30mm
Magnification Greater than or equal to 32 times
Horizontal Circle        1o graduation
Compensator Air or Magnetic damping  
Compensator Range      Not less than + 10'
Compensator Accuracy      Not greater than +0.3"
Standard Deviation of 1 km double run  Not greater than + 1.5mm
Minimum Focus        1.6m
Levelling Mechanism      Foot Screws


5.2 Construction Level

These levels would typically be used for minor works and 4th Order levelling.

Type    Automatic
Image    Erect
Objective Aperture     Greater than or equal to 30mm
Magnification Greater than or equal to 25 times
Horizontal Circle        1o graduation
Compensator Air or Magnetic damping  
Compensator Range      Not less than + 15'
Compensator Accuracy      Not greater than +0.5"
Standard Deviation of 1 km double run  Not greater than + 2.5mm
Minimum Focus        1.6m
Levelling Mechanism      Foot Screws


6 TYPICAL SPECIFICATION FOR ELECTRONIC LEVELS



6.1 4th Order Level & Staves

Typically used for Road Reference Mark surveys.

Image   Erect
Objective Aperture  36mm  
Magnification  24 times  
Horizontal Circle   360o
Compensator Pendulum with electronic range control
Compensator Tilt Range   + 12'
Compensator Settling Accuracy  +0.8"  
Standard Deviation of 1 km double run    
          Electronic   1.5mm using specified stave
          Optical   2.0mm
Distance function   preferred
Electronic Measuring Range   1.8m to 100m
Minimum Focus (Optical) 0.6m  
Measuring Time (typical) 4 sec  
Internal battery life To allow full days work from 1 battery
Staff   4m dual face : barcode/cm


6.2 3rd Order Level & Staves

Typically used for control surveys requiring mm accuracy 

 

Image                                                       Erect
Objective Aperture     36mm  
Magnification  24 times  
Horizontal Circle        360o
Compensator Pendulum with electronic range control
Compensator Tilt Range      + 12'
Compensator Settling Accuracy   +0.4"  
Standard Deviation of 1 km double run    
          Electronic         0.5mm using specified stave
          Optical        2.0mm (using normal graduation stave)
Distance function        Required
Electronic Measuring Range     1.8m to 60m
Minimum Focus (Optical)   0.6m  
Measuring Time (typical)   4 sec  
Internal battery life     To allow full days work from 1 battery
Staves (Matched pair)      
 
  3m Invar or fibreglass : Single Face : Barcode

 



7 TYPICAL DUAL FREQUENCY GEODETIC TYPE GPS

These units are kept and maintained by the Surveying and Geospatial Services branch.They are expensive units requiring specialist skills to operate and process data. These units may be used for control densification in Static mode or full detail pickup(except hard surfaces) in RTK mode.

The following specifications are typical:

  • High precision multiple correlator for GNSS psuedorange measurements
  • Very low noise GNSS carrier phase measurements
  • 72 channels
     

Static and Fast Static surveying precisions:

Horizontal:                                     +/- 5mm  + 0.5 ppm
Vertical :                                         +/-  5mm + 1 ppm


Kinematic surveying precisions:

Horizontal :                                   +/- 10mm  + 1ppm
Vertical :                                        +/- 20mm  + 1ppm
Initialisation time :                       typically 10 seconds

Hardware:

Weight     :                   - approx  1.4kg GPS unit only
                                     - approx  3.7kg unit with pole,battery,data recorder

Operating temperature:      - 40deg to + 65 deg.
Water/dustproof :                 IP 67 standard dustproof:temporary immersion to 1 metre
Shock/vibration  :                 withstand a 2 metre pole drop onto concrete

Electrical:                          : 11 to 28V DC
                                            : Rechargeable,removeable lithium ion battery


Communications and data storage

  • 7 pin lemo on port 1 plus full RS-232 serial on Port 2
  • Fully integrated and sealed 450 MHz receiver/transmitter option
  • Fully integrated 2.4GHz Bluetooth port
  • External cell phone support for GSM.
  • Data storage on 11 MB internal memory
  • 1,2,5,10 Hz positioning
  • RTCM input and output
  • NMEA output-various types


8 GPS --- HANDHELD TYPE

There are numerous types of handheld units within Mainroads WA but typically
They may conform to the following.

  • Instantaneous positional accuracy of 3 to 5 metres
  • Dustproof, waterproof(splashproof)
  • Menu driven or touch screen
  • Waypoint storage for 500 to 1000 points.
  • SD card or onternal memory
  • Battery(usually AA type)driven-up to 10 hours continuous use.
  • Built in or optional maps
  • Upload/download capability through proprietary software.


9 SPECIFICATIONS FOR ANCILLARY EQUIPMENT

9.1 To be compatible with supplied Robotic Total Station

 

Prism pole


      x 1


2m telescopic graduated in centimetres such that graduations are compatible with the following prism combinations for the Robotic application:
Triple Prism set    x 1 zero constant, with target
Single prism with holder         
  
x 1
zero constant, with target for use with tribrach mount.
360 degree passive single prism x 1 zero constant, for use with prism pole.

Tribrach
Tribrach to prism adapter



x 2

 

 

Incorporating an optical plummet,
Tribrach to prism adapter  compatible with the electronic theodolite's optical plummet system.  i.e. if the theodolite tribrach has an optical plummet then so must the ancillary tribrach or vice versa.
Radio Modems x 2 Freewave Radio Modems and tripod pouches
Remote Surveying Controller  x 1 Remote survey external controller
12v battery    
Barometer(For accurate
monitoring surveys)
x1
Graduated in mm, 2mm graduations
Thermometer(For accurate
monitoring surveys)
x1
1 degree graduations in solid casing
Transport case

x1

To hold all of the above, except poles, plus power supply components not in Robotic Theodolite case.
Tripod 
x3
Timber, heavy duty, telescopic flat head.  Extended length 1.7m.
Instrument Height Pole 

x1

Graduated in centimetres, compatible with electronic theodolite and all supplied tripods.


9.2 To be compatible with supplied manual Total Station

 

Prism pole

x 1

2m telescopic graduated in centimetres such that graduations are compatible with the following prism combinations:
Triple Prism set    x 1 zero constant, with target
Single prism with holder         
  
x 1
zero constant, with target for use with tribrach mount.
Single prism with holder          x 1 zero constant, for use with prism pole.

Tribrach plus
Tribrach to prism adapte


x 2


 

Incorporating an optical plummet,
compatible with the electronic theodolite's optical plummet system. i.e. if the theodolite tribrach has an optical plummet then so must the ancillary tribrach or vice versa.
Barometer(For accurate
monitoring surveys)
x1
Graduated in mm, 2mm graduations
Thermometer(For accurate
monitoring surveys)
x1
1 degree graduations in solid casing
Transport case

x1

To hold all of the above, except poles, plus power supply components not in Electronic Theodolite case.
Tripod 
x3
Timber, heavy duty, telescopic flat head.  Extended length 1.7m.
Instrument Height Pole 

x1

Graduated in centimetres, compatible with electronic theodolite and all supplied tripods.


9.3 To be Compatible with Supplied Level

9.3.1 Electronic Level

Tripod           Timber, telescopic flat head.  
                       Extended Length 1.7m.

9.3.2 Surveyors Level

Tripod           Timber, telescopic flat head.
                       Extended Length 1.7m.

Staff              Aluminium, Australian metric 0.5cm face, 5m, 4 piece telescopic.

9.3.3 Construction Level

Tripod            Aluminium, heavy duty, telescopic flat head.  Extended Length 1.7m.

Staff               Aluminium, metric 1 cm E face, 5m, 4 piece telescopic.



10 REFERENCES

The following documents relate to this Guideline: 
 
Surveying and Geospatial Services Standard 67-08-43 "Digital Ground Survey"
Surveying and Geospatial Services Guideline 67-08-107 "Settlement Monitoring Surveys"



11 APPENDIX A-TESTING AND ADJUSTMENT OF SURVEY EQUIPMENT

The following is provided as information only and is a suggested methodology for the testing and adjustment of standard survey instrumentation.

1.0    Testing and adjustment of Optical Theodolites, Electronic Theodolites and Total Stations

The following procedure shall be undertaken for the testing of  horizontal and vertical collimation in Optical Theodolites, Electronic Theodolites and Total Stations. 

These procedures shall be read in conjunction with the handbook for the instrument as the testing procedure and adjustment does vary between different makes and types of instruments such as optical or electronic.


When an instrument is to be tested and if necessary adjusted it should be set up on firm ground and the tripod should form a stable support.

1.1    Horizontal Plate Bubble Adjustment

  • Set the instrument up, by means of the bubble, so that the vertical axis is approximately vertical.
  • Set the bubble across two foot screws and bring the bubble to the centre of its run.
  • Rotate the plate exactly 180 degrees (use the horizontal circle for accuracy).
  • If the bubble is in adjustment it will remain central.  If not it may be adjusted by taking half the error out with the foot screws and half with the bubble adjusting screws.

Repeat the procedure to check the adjustment is applied correctly.
 
1.2    Adjustment of the Cross-Hairs

 As the horizontal and vertical adjustments are linked, they should be carried out jointly and both conditions satisfied before proceeding to adjustment 1.3

1.2.1    Adjustment for Horizontal Collimation

  • Select an area of cleared level ground and set up the instrument between point A, a definite point greater than 500 metres away and a tripod approximately 100m from the instrument.  Make the vertical axis vertical.

horizontal-collimation.GIF

 

  • At point A choose a reference object which is a definite point greater than 500 metres away and approximately the same level as that of the instrument.
  • At point B set up a horizontal scale or staff so that the top is about the same level as the instrument.
  • With the telescope on face left., sight on point at A.
  • Transit the telescope and note reading on B.
  • Rotate the telescope horizontally and point back at A (it will now be pointing face right).
  • Transit the telescope again and note the second reading at B.
  • If the readings are identical the instrument is in adjustment.  If not the instrument should be adjusted so the line of sight is moved ¼ of the distance towards the first reading.

Repeat the procedure to check the adjustment is applied correctly.

1.2.2    Adjustment for Vertical Collimation

  • Set the instrument up so that the vertical axis is vertical.
  • Point the telescope so that the top, or bottom, of the vertical hair is aligned on some clearly defined target and clamp the telescope. An example of  a well defined point is a plumb-bob hanging from a fixed point.
  • Lower, or raise, the sight by means of the vertical circle tangent screw and watch the apparent travel of the target along the vertical hair.
  • If the target remains aligned with the vertical hair throughout the whole movement, then the vertical hair is perpendicular to the horizontal axis. If it does not then the instrument must be adjusted until the desired relationship exists.  To do this, may upset the horizontal collimation adjustment.

Repeat the procedure 1.2.1 and 1.2.2 to check the adjustments have been applied correctly.

1.3    Horizontal Axis Adjustment

  • Set up the instrument with the Vertical Axis exactly vertical.
  • Direct the telescope to a clearly defined high point A, example on the top of a high wall.  The angle of elevation should be at least 30°.
  • Lower the telescope to a horizontal position and make a mark B on the wall.
  • Reverse face and repeat the last two steps.

If the two marks at B coincide the instrument is in adjustment.

  • If the two marks do not coincide, direct the line of sight to the mean position at B using the horizontal tangent screw.
  • Elevate the telescope to sight A.  Because the line of sight has been moved it will not pass through A.  The adjustment consists of moving the line of sight until it does pass through A.  This is achieved by adjusting screws on the transit axis as per the handbook for the instrument.

Repeat the procedure to check the adjustment is applied correctly.

1.4    Vertical Circle Index Adjustment

  • Set the instrument up and level it.  Point the line of sight at a wall or a staff.
  • Make the vertical circle read 90 or 270 degrees, using the vertical circle tangent screw and, if necessary, the micrometer setting knob. 
  • Make a mark where the line of sight strikes the wall (or read the staff).
  • Change face and repeat the last two steps.

If the marks (or the readings) coincide the instrument is in correct adjustment, otherwise :

  • Set the line of sight on the mean reading (using the vertical circle tangent screw).  The line of sight will now be horizontal, but changing the line of sight will have altered the zero setting.
  • Set the vertical circle to read zero by adjusting either 
         -  the clip screw, if present, or
         -  the vertical circle adjusting device on an Automatic instrument.

Repeat the procedure to check the adjustment is applied correctly.

1.5    Adjustment Screws

Ensure when adjusting an instrument that the last movement of the adjustment screw is clockwise (tightening) to prevent the instrument falling out of adjustment.

1.6    Recording of Tests

All tests for the adjustment of optical theodolites, electronic theodolites and total stations shall be recorded in a Survey Equipment Field Test Record sheet and filed with the equipment records.
 

2.0    Testing and Adjustment of Survey Levels

 Survey levels can be tested and adjusted using the procedure known as the ' Two Peg Test'.

2.1.    Set-up One

Set the instrument up midway between 2 pegs A and B, 60 metres apart on fairly level ground.  Level the instrument and read the staves at pegs A and B  (a1 and b1). This will give the true difference in height,  Δ H, between pegs A and B. In Figure 1 below, the line of collimation is inclined downwards by an angle causing the staff reading at A to be in error by an amount e. Note that because peg B is exactly the same distance from the instrument as peg A the same error e occurs. This same error e is applied to each staff reading and thus the true difference in height can be found. 

Note:   This difference may have been determined from previous tests on two fixed points.  In the case where the true height difference is known this step may be omitted.  Fixed points shall be tested and results recorded at least once every six months

 

survey-levels-1.GIF
 


2.2.    Set-up Two

Set up approximately 2 metres behind the staff at A, in position 2. Centre the circular bubble and record the staff readings a2. Apply the difference in height, Δ H, to reading a2 to predetermine the reading b2. Read the staff at position B, as shown in figure 2 below, compare the two values.

 

survey-levels-2.GIF 


 
2.3     Adjustment
 
If the actual reading differs from the pre-determined value b2 by more than 2mm, then the level should be adjusted using the adjustment screws on the eyepiece of the instrument and in accordance with the handbook for the instrument. Ensure the last movement of the adjustment screw is clockwise (tightening) to prevent the instrument from falling out of adjustment.

Always repeat the procedure to ensure the instrument is now in adjustment.


2.4     Example of a Two Peg Test


 two-peg-test.GIF


After readings are taken at the 2nd position, the difference = 0.691 (2.833 - 2.142), instead of 0.705 (2.074 - 1.369) as at the 1st position. Thus the level has an error of 0.705 - .691 = 0.014.


The correct reading at B should be 2.847 (2.142 + .705); the level is adjusted to this reading using the adjustment screws on the eyepiece of the instrument and in accordance with the handbook for the instrument. For this example, the following would be entered in a Level Calibration Field Record Sheet . (the tabulation includes a recheck)

 


OBSERVER....................................                              DATE........................

 

 BACK

 FORE

RISE 

FALL

DIST 

 REMARKS

 1.369   2.074      0.705   30 / 30   
 2.142  2.833    0.691    2 / 62  Misc 14mm Adjusted
 1.401  2.105    0.704  30 / 30  Check
 2.151  2.856    0.705    2 / 62  OK

3.0    Calibrated Survey Measuring Band

Calibrated measuring bands in continuous use should be calibrated annually. Calibrated measuring bands used only for standardisation of measuring equipment should be calibrated every five years. The calibration shall be performed under  Landgate supervision, using an approved procedure and certified as to its accuracy.

The original of the calibration certificate shall be filed with the equipment records, and a copy issued with the calibrated measuring band.

4.0   Differential Levelling Staves

4.1    Calibration

Annual calibration of all differential levelling staves is recommended. The calibration is to be performed on the Landgate Test site in Boya , using an approved procedure.

The calibration certificate shall be placed on the equipment file and a copy issued with the staves.


4.2     Calibration Factors

Staff calibration factors can be obtained from the latest calibration certificate attached to the differential staves.These are used to provide final adjusted levels in a levelling traverse when completing a level abstract form. If there is a large height difference along the traverse then the Calibration factor will make a significant difference in the final adjustment.

 

5.0    Tribrachs and Optical Plummets

5.1    Field Testing Method

  • Set tribrach or optical plumb on instrument legs and level using bubbles.
  • Using plumb-bob supplied with suitable attachment to instrument legs, mark truly vertical point.
  • Remove plumb-bob and check optical plumb for coincidence with point marked.
  • Adjust (move cross-hairs) using adjustment screws.  Ensure the last movement of the adjustment screw is clockwise (tightening) to prevent the tribrach from falling out of adjustment.

Repeat the procedure to check the adjustment is applied correctly.
 
For tribrachs or optical plummets that can be rotated an alternative method can be used by rotating the mechanism through 60 degrees and plotting the circle of error. The error can be then removed by moving the cross-hairs using the adjustment screws.

 

6.0    Levelling Staves

These  are to be tested by a visual inspection of the staff face, condition of the foot and joints and measuring with a five metre steel tape, which has been tested against a calibrated survey measuring band. 

A comparison of  staff graduations against equivalent marks on the steel tape shall be made over the entire length of the staff. 

Should any reading disagree by more than 2 millimetres for a 5 mm staff face or 4 mm for a 10 mm staff face, the staff shall be not be used and clearly marked as such.

7.0    Poles, Survey Bands, and Tapes

All Poles, Survey Bands and Tapes shall be tested by a visual inspection for condition of the item and by measuring against a calibrated baseline or a calibrated survey measuring band.

All Poles, Survey Bands and Steel Tapes shall not be used if any graduation is in error by 5 millimetres or more.

Poles should be straight and the level bubble checked regularly for adjustment (by using a detachable staff bubble)

All fibreglass or cloth Tapes shall not be used if any graduation is in error by 50 millimetres or more.

 

8.0     Measuring Wheel

Measuring wheels shall be tested by a visual inspection for the condition of the item and by measurement against a calibrated baseline or calibrated survey band. Measuring wheels shall not be used if the measured distance is +0.1 metres over  50 metres.

9.0     GPS/GNSS Systems

The Curtin University GPS/GNSS testing pillar network should be used together with thier recommended observation and data processing techniques. In this way, results for baselines observed can be compared to those of the network to ensure that the GPS/GNSS receiver used is performing to the manufacturer's specifications and that the processing software used produces the desired outputs for analysis.