Construction Surveying

Document No:  D12#434555
 
Revision:  7A
 
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 the Senior Engineering Surveyor by e-mail or ph MRWA Contact Centre 138 138.

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 below.

 

Revision Register

 

Ed/Version Number Clause Number Description of Revision Date
 1 All  Guideline Developed  13-June-2001
 2 2.5 Update link to DGS standard  07-May-2009
 3 All Guideline Revised and Approved. 14-Aug-2009
 3A All Links to Road Reference Marks updated. 04-Oct-2010
 3B All Links to Road Reference Marks updated. 25-May-2011
 3C 2.1.1, 2.1.2, 2.2, 2.4, 4.3, 4.6 and 8.2 Links to Road Reference Marks updated. 29-Nov-2011
 3D All Links to Road Reference Marks updated. 09-Mar-2012
​4 ​All ​Content Cleanup ​5-Feb-2013
​5 ​All ​Changes from 3rd order to differential ​12-Feb-2014
​6 ​Header ​Document Number Changed ​16-Jun-2014
​7 ​All ​Guideline Revised and Approved ​23-Jun-2014
​7A​Header​Guideline Introduction Amended​14-May-2015

Table of Content


GENERAL

The following guideline has been developed to assist, project managers, superintendent's and their representatives in sourcing the survey construction needs of their projects using internal and/or external support.

1 SURVEYING PERSONNEL

1.1 CONTRACTOR'S SURVEYOR (SCC15)

  • The contractor shall only use surveyors who are third party certified to AS/NZS ISO 9001:2008.
  • Alternatively, where the contractor uses their own in-house surveying resources, the contractor's third party certified quality system should include surveying as a special process.
  • A surveyor who is eligible for Membership of the Surveying & Spatial Sciences Institute as a certified engineering or mining surveyor shall be on-site at all times during survey work.

1.2 SUPERINTENDENT'S SURVEYOR

As Above.

1.3 PROCUREMENT OF SURVEY SUPERINTENDENTS SURVEYOR FOR AUDIT AND SUPPORT SERVICES

Due to the irregular frequency of survey audit and support requirements on construction contracts, it is recommended that flexibility be built into the contract when engaging survey audit and support services for the lifetime of a project. In addition to flexibility other considerations should be given to response time, availability and mob/demob costs particularly on remote rural projects.

MRWA primarily uses Contract 291/09 Survey and Mapping Panel Contract and/or Engineering Technical Services procurement of survey and audit services:

 

  • Contract C291/09 Survey and Mapping Panel Contract

     Survey Services 1: Request Form C291/09

  • Period Contract for Engineering Technical Services
    The following ETS survey audit and support briefs are available for general use and may be modified to suit individual project requirements:
    ETS Survey Audit and Support For AS2124
    ETS Survey Audit and Support For Design and Construct

  • Public Tender
    Up to $5,000: - Direct Purchase
    $5,001 - $20,000: - Request sufficient verbal quotations
    $20,001 - $150,000: - Request sufficient written quotations. 
    Above $150,000: - Open tender through a public advertisement

2 CONSTRUCTION SURVEY CONTROL

The control network provides the basis for all design set out, measurement, compliance and audit surveys and  therefore represents the critical datum reference for all road construction projects. The accuracy and quality of the network will directly affect the quality and accuracy of the final product and earthwork measurements for payment.

2.1 ESTABLISHMENT

2.1.1   Random Construction Control

A network of control points must be established over the proposed construction area.

All construction control shall be located, installed and surveyed in accordance with MRWA Survey and Mapping standard 67-08-36 "Road Reference Marks".

2.1.2   Bridge works

The contractor must establish/nominate two random construction control points for each bridge site. The two marks will provide line, level, and origin for the bridge set out. Only these control points should be used for the bridge construction. This will eliminate the introduction of error from additional control and ensure a high level of relative internal precision as opposed to absolute location.

All construction control shall be located, installed and surveyed in accordance with MRWA Survey and Mapping standard 67-08-36 "Road Reference Marks".

2.2 RE-ESTABLISHMENT:

  • If during the construction phase, control points have to be relocated or additional points installed, then these points shall be connected to the existing network and surveyed in accordance with the MRWA Survey and Mapping standard 67-08-36 "Road Reference Marks".
  • Computations of coordinates for these new control points shall be ancillary to the main traverse adjustment so that minor adjustments to previously fixed points are avoided.

2.3 CONTROL NETWORK VERIFICATION AND MAINTENANCE

  • If the survey control has been established prior to the start of construction, the superintendent's representative should check to ensure the survey control points have not been disturbed or moved. An agreed value between principal and contractor for all road reference marks must be obtained prior to commencement of construction.
  • Verification of the control network should be conducted periodically over the project duration by the contract surveyor. The frequency will vary in accordance with the environment. For example, control points located in marshland are more prone to subsidence than those located in pindan soils.
  • If discrepancies are observed between adjacent control points and they appear undisturbed then this may indicate a need for network verification.
  • The verification process should be clearly indicated in the quality plan.

2.4 PROTECTION OF SURVEY MARKS

  • Any road reference marks disturbed by the contractor during construction will be replaced by the contractor in accordance with MRWA Survey and Mapping standard 67-08-36 "Road Reference Marks".
  • The contractor will be responsible for all associated re-establishment costs resulting from any disturbance to existing established survey marks (BM's,SSM's and boundary/ fencing pegs) resulting from the contractor's activities under the contract.
  • When the contractor is required to re-establish either of these types of mark, the following will apply:

(a) Cadastral Marks: In accordance with the Landgate regulations, a licensed surveyor must carry out all re-establishment cadastral surveys. The contractor will ensure that its licensed surveyor provides a "Regulation 25A certificate" for the superintendent upon completion of the survey.

(b) SSM's and BM's: The contractor must, through the superintendent, notify the Main Roads Senior Geodetic Surveyor who will arrange re-location and/or replacement through Landgate. Once the notification has been made, no delay to the works is required for the re-location and/or replacement of SSM's and BM's, unless directed otherwise by the superintendent.

2.5 CONTROLLED SURVEY MARK RECORDS

  • The contract surveyor shall maintain a site listing of all the survey control mark coordinates, summary sheets and adjustments. A logbook shall be available indicating control point history clearly indicating where survey points have been disturbed or moved.
  • This process should be clearly indicated in the quality plan.

3 MAIN ROADS SUPPLIED SURVEY INFORMATION FOR SET OUT

To enable survey set out to be performed on a construction project, the following information should be supplied to the surveyors onsite. This is the minimum information required to perform all survey duties pertaining to the project.

  • Digital Design Model
  • A1 Construction Drawings
  • Survey Control Point listing and Summaries (Note this information can be sourced from Main Roads' Survey Portal)
  • Technical Specification
  • String reports (992 MX output) and cross section reports (994 MX output) can be supplied if requested.

MX Digital Design Amendments

In the event of a digital design amendment, the following information should be supplied to the contractor:

  • The amended full digital design in default MX genio format (cleaned of all designer construction strings);

and in addition

  • A separate MX genio file consisting of just the amended design strings.

This enables the surveyor the option of updating his design model with just the amended strings (in the event significant work as been conducted on the surveyor's model to date) or replacing the entire model.

4 SURVEYING as a "SPECIAL PROCESS" - (AS 2124 Contracts Series 201)

Where the surveyors are not 3rd Party Certified the construction contractor's quality system requirements, Special Process procedures shall be prepared for all surveying and measuring activities. The contractor shall treat as a "special process" those surveying and measuring activities which:

  • Verify conformance with all design surfaces, layers, dimensions, locations and positions within specified tolerances.
  • Determine lengths, areas or volumes of materials, products or scheduled work items within specified tolerances.

In some cases the procedures provided may simply consist of a cross-reference to another section of the contract quality plan, or to existing procedures in the contractor's quality management system. In the former case, the cross-referencing must occur in both sections of the plan.

It is recommended that at a minimum, the following criteria are addressed in the quality plan, and where applicable cross-reference made to the relevant Survey and Mapping standards.

 
 

4.1 QUALIFICATIONS, EXPERIENCE AND RESPONSIBILITIES

4.1.1   Contract Surveyor (as defined in SCC 15 clause 28.5 ):

  • Eligible for membership within the Surveying and Spatial Sciences Institute as a certified Engineering or Mining Surveyor,
  • Knowledge and understanding of the different accuracy classes for control surveys, construction set out surveys and construction audit surveys,
  • Knowledge and understanding of the different materials/construction methods to be used for each class of control point.

For Road Construction Contracts:

  • Knowledge and understanding of the interpretation of MX genio digital design models and use of road construction plans, string reports, etc for construction set out.

For Bridge Construction Contracts:

  • Knowledge and understanding of the interpretation of MX genio digital design models and use of bridge structural construction plans, etc for construction set out.
  • Knowledge and understanding of deformation monitoring.

For Compliance (Audit) Surveying:

  • Knowledge and understanding of analysis / statistical reporting of audit results against digital design models.

 

4.1.2   Surveyors Responsibilities- Typical

  • Prepare set out data from plans and digital design, prior to and during construction.
  • Identify any design errors or ambiguities and provide immediate feed back to project manager.
  • Implement any design changes as advised.
  • Collect and collate data to assist with reports and to monitor project progress.
  • Ensure suitable survey procedures and accuracies are adopted for construction set out to satisfy required accuracies.
  • Maintain a current survey control listing and update as necessary.
  • Maintain and periodically calibrate survey instrumentation to ensure good working order.
  • Maintain a complete record of surveys for inspection by the quality control officer or project manager.

4.2 SURVEY EQUIPMENT AND CALIBRATION

The following items need to be addressed:

  • Storage and handling.
  • Calibration regime.
  • Types of equipment and fitness for purpose.
  • Details of computer hardware / software for survey computations.

4.3 SURVEY CONTROL ESTABLISHMENT & MAINTENANCE

The following requirements apply to existing (Principal Supplied) control, and control installed under the contract:

  • Verification of existing survey control network.
  • Action required if control not in place or additional control to be installed.
  • Maintenance of control - method / frequency of audit, records.
  • The quality plan shall document the contractor's intended compliance with the contract specifications and MRWA Survey and Mapping standard 67-08-36 "Road Reference Marks", specifically clause 6.0 "Random Construction Control" for the maintenance and re-establishment of the control network.
 
 

4.4 SURVEY METHODS FOR SET OUT AND COMPLIANCE

The following should be documented in any contract:

  • Required accuracy, frequency and methodology for different stages of construction.
  • Survey methods for major structures. i.e. All major structures will have separate fixed control stations established solely for setting out those structures. The relative position of the structure is more critical than the absolute.
  • Survey methods for joint surveys.
  • Survey methods for compliance surveys.
  • Overall responsibility matrix defining the reporting line for the surveyor.

 

4.5 SURVEY DATA CONTROL

  • Data storage/ backup / registration: who, when, where, why, how, must all be recorded.
  • All digital terrain models shall be supplied in MX Genio format.
  • All naturally occurring and man made features, both above ground and below, shall be captured, labelled and lodged in accordance with the MRWA Survey and Mapping standard 67-08-43 "Digital Ground Survey".

4.6 DOCUMENT CONTROL

Documentation of the process for data storage,  back up, registration and controlled distribution of survey records on site. The procedure should include reference to:

  • Certificates, sketches, tables and printouts prepared and endorsed by surveyors.
  • Product conformance spreadsheets and reports.
  • Field notes and calculations
  • Calibration certificates and records.
  • A register of all raw data files and the purpose for which they were taken.
  • A register of all computer jobs (with a description of their purpose) created for volume calculation or set out, or verification.
  • A register of field book allocations, issue dates and contents.
  • A control registry which should include summary sketches, least square and differential level adjustments, field observations and quality statements, as stipulated in the MRWA Survey and Mapping standard 67-08-36 "Road Reference Marks".
 
 

4.7 REPORTING STANDARDS FOR AS CONSTRUCTED DATA (COMPLIANCE SURVEYS)

  • Provide an audit schedule for each lot stipulating the product to be sampled; sampling frequency, size and observation density; and order of accuracy and confidence level.
  • The quality plan shall include a sample of presentation for the compliance reporting.
  • At a minimum the compliance report spreadsheet should include the Easting, Northing, Chainage and offset of the observed point and the corresponding ascon elevation and design elevation. The spreadsheet should include the elevation differences and a status of compliance for each sample point relative to design tolerances.

5 CONSTRUCTION PEGGING

It is the responsibility of the contract surveyor to determine and undertake all construction pegging requirements. This section has therefore been included as a guide only based on past MRWA practice.

RTK GPS complies with vertical accuracy to Sub-Grade only. It is not to be used for vertical set out on base course final level or for structural set out (vertical or horizontal).

RTK GPS provides an acceptable accuracy for horizontal set out of all sub grade, sub base and base course pegging.

5.1 CONSTRUCTION PEG SET OUT

5.1.1   Clearing Line

  • The clearing line is pegged to enable removal of topsoil and vegetation.
  • Pegging is done by either stakeout from digital design model using RTK GPS, string line radiation, offsetting from previously set out string lines, scaling and measuring from the plan using established features such as fences, edge of road, cadastral boundary etc.
  • Accuracy required for this work is generally 0.5m or as specified by the contract documents or the project engineer.

 

5.1.2   Batter Line

  • The batter line shall be set out by either stakeout from digital design model using RTK GPS, string line radiation or from cross section reports which define position and level.
  • It is necessary to confirm the actual ground levels at points set out as any level discrepancy affects the batter grade, hence to string line radiation shall be used as a guide only.
  • The toe of batter shall be located where the design batter slope from the hinge point intersects with the natural surface.
  • Accuracy for batter pegging is generally 0.2m horizontally and 0.1m vertically or as specified by the project engineer.
  • During construction of the batter, the shape is generally controlled either by the stepping method or fixed batter boards depending on the depth of the earthworks and the soil type.

 

5.1.3   Drainage Manholes, Gullies and Culverts

  • Position is set out from the primary control and the pegs are placed at an offset to enable excavation and construction.
  • Pegs are marked with the centre line offset, top of excavation offset and cut to invert level.
  • To ensure the structure remains parallel to the kerb line, additional points may be required adjacent to the structure on the kerb line.
  • Vertical accuracy in drainage works especially flat terrain, is critical and shall be surveyed to 5mm, or as specified in the contract docuyment and/or Project Manager.
  • For sub soil drains and table drains the horizontal and vertical alignment of these structures is set out using the appropriate string line from the cross section report.

 

5.1.4   Formation

  • The edge of formation is set out using the verge or shoulder strings and is placed by either stakeout from digital design model, string line radiation from the cross section reports or by offset from the existing centre line pegging.
  • The shoulder string is usually offset by 0.3 - 1.0m to allow compacting machinery to operate to the edge of the formation. If the verge string is set out, no offsetting is usually required. These string lines form the basis of horizontal and vertical control for the pavement construction. It is the surveyor's responsibility to maintain a continuous control on alignment and levels.
  • The pegging interval for sub-grade should be no more than 20 metres and every 10 metres for sub-base and base-course.
  • When machine guidance with GPS or laser is being used then it is recommended that shoulder pegs are installed every 200 metres so that chainage is readily located.

 

5.1.5   Priming, Sealing Edge

  • Usually only one edge of the pavement requires marking out for the primer seal edge to ensure that spray run is on correct alignment and uniform.
  • The alignment should be nailed every 10m with spring head nails and flagging under the nail for better visibility. Paint can also be used for better visual affect.

 

5.1.6   Kerbing

  • Set out will be to face of kerb.
  • Kerbing alignments shall be surveyed in from control points and nailed with springhead nails and flagging.
  • Intervals between nails should not exceed 15m on straights and 5m on large radius curves. On traffic islands and median noses, the interval must be adequate to define the alignment clearly and precisely.

 

5.1.7   Asphalt Pavement, Lane Marking

  • Before asphalt paving can proceed, the proposed lane marking has to be established in order for the asphalt joins to coincide with the line markings.
  • The markings shall be established in accordance with the MRWA Survey and Mapping Guideline 67-08-40 "Spotting in Preparation for Longitudinal Line Marking".
  • These may be set out using RTK GPS.
 
 

5.2 PEG COLOUR CODING SYSTEMS

5.2.1   Urban Projects

  • As a guide for metropolitan projects, construction pegs can be colour coded as follows:

 

metro1x.gif.GIF 

 

Setting Out Colour System

For box construction, surveyors should set out finished levels only, using yellow self adhesive tape.

NOTE: Bottom of the tape denotes the finished level. In cases where this is not possible because the design level is below the surface, red tape shall be used and depth of cut marked on the stake, usually in 0.5m divisions.
Other pavement layer levels are measured down from the yellow (finished level) tape by construction personnel.

For construction set out (Rural Type) as illustrated, the surveyor should set out all levels.

5.2.2   Rural Projects

  • In regards to rural projects, the following offers an alternative where phases of work are indicated by respective coloured ribbon variations.

 

rural1x.gif.GIF 


A4 print outs are available from the following links:

Metro Projects.doc
Rural Projects.doc

 
 

5.3 CONSTRUCTION PEG OFFSETS AND INTERVALS

  • Construction pegs will be located at fixed offsets from their design positions to avoid disturbance from machinery and to ensure compaction to the road edge. The offset distance shall be set by the project engineer and can vary from 0.3 - 1.0m from project to project.
  • The pegging interval will vary according to the type of work and the construction environment.
  • Generally, the pegging interval is the same as the cross section drawings, however additional cross sections may need to be created from the digital model as required. Metropolitan projects usually peg at 10m intervals due to the increase in complexity of designs and drainage.
  • Less traffic and coarser tolerances result in most rural projects being pegged at 20m intervals.
     

5.4 PEG ANNOTATION

  • To define levels, self adhesive tape (eg insulation tape) is attached to each peg so that the bottom of the tape is at the construction level for that peg position.
  • Due allowance shall be made for the offset distance when determining construction levels so that the level is placed with cross fall taken into account.
  • In areas of cut the level placed on the peg shall be an even increment of 0.5m from the final level and the amount of cut to come down from the tape clearly marked on the peg.
  • Pegs should be clearly annotated with a reference chainage relative to the master alignment, an offset relative to a reference design string and the reference design string label.

5.5 PEG MATERIALS

  • Pegs can be timber, aluminium, steel or plastic depending on environmental constraints and local needs.
  • The pegs are driven firmly into the ground, positioned vertically and annotated with the respective chainage, offset from the centre line and design elevation.
  • All pegs are to be placed within 50mm of their true horizontal position.

5.6 PEGLESS CONSTRUCTION

  • Modern construction techniques are now utilising machine control technologies to enable them to construct with minimal pegging. Project Managers must be aware that GPS technology will not enable final pavement level tolerances to be achieved and Laser systems must be utilized for final pavement accuracy.
  • All AS2124 Contracts require pegging at a minimum as stated in General Requirements 100 Series (102.06).

6 MEASUREMENT SURVEYS

Measurement surveys or foundation surveys, are performed by the superintendent. This survey defines a particular surface of a feature for area and volume earthwork computations and subsequent schedule of rates payment.

Measurement surveys are used to determine:

  • Actual earthwork quantities against design quantities (extent of cuts and fills, batter slopes etc).
  • Identification of lots and layers for embankment fill (i.e. to control and ensure that all lots were tested for compaction).
  • Calculating volumes of cuts and embankment  fill.
  • Calculating foundation areas for payment verification.

6.1 EMBANKMENT FOUNDATION SURVEYS

Embankment foundation surveys (stripped ground surveys) are performed prior to the commencement of any earthworks or culvert work, and subsequent to clearing, removal of topsoil and compaction of the embankment foundation.

The contractor shall give the superintendent at least 24 hrs notice of when levelling is required for the purpose of earthworks measurement.

6.2 JOINT SURVEY REQUIREMENT

  • Joint surveys are performed when both the superintendent's and contractor's surveyor are present during the field observations. This minimises disruption.
  • There is no set joint survey procedure for data capture, this is usually agreed on site between both parties. The observations are performed using either party's total station and or RTK GPS.
  • Joint surveys can help eliminate issues relating to the ground model integrity in the event volume discrepancies should arise over the course of the project. It is recommended joint surveys be performed on all earthworks where the volumes are a schedule of rates payment.
  • A hardcopy raw data output of the survey should be signed in agreement by both parties and forwarded, with the digital ground model, to the superintendents representative. The raw data output should include the date of survey and a descriptive of the lot location, survey methodology and equipment used.

 

6.3 TYPICAL MEASUREMENT SURVEY APPLICATIONS

6.3.1   Area Definition

  • Clearing
  • Spoil and borrow pits
  • Sub grade
  • Bitumen removal

 

6.3.2   Volume Definition

  • Borrow pits
  • Rock
  • Unsuitable material
  • Stockpiles
  • Bulk earthworks / mass haul.

6.4 CONTROLLED DATA RECORDS

  • Copies of all details including survey requests, raw data hardcopies and MX genio files of the digital ground model should be retained by the superintendent's representative. The lodged information should be supplied to the superintendent's representative in accordance with the lodged information and data format requirements stipulated in the MRWA Survey and Mapping guideline "Data Lodgement".
  • In regards to joint surveys, a hardcopy of the raw data (unprocessed observational data  direct from instrument) is signed in agreement by both parties and forwarded, together with the MX genio digital terrain model, to the superintendent's representative. The raw data output should as a minimum include a date, lot location, survey methodology and equipment used. Control points used during the survey and appropriate check shots should be clearly defined in the raw data.

7 COMPLIANCE SURVEYS

Compliance surveys are undertaken by the contractor to ensure as constructed products comply with project specification tolerances. They are usually required on 100% of all as constructed surfaces and structures.

The compliance survey results provide the superintendent's representative with evidence for the release of hold points. The survey results should clearly indicate the product to be sampled; sampling frequency, size and observation density; and order of accuracy and confidence level. These criteria should be reflected in the contractors quality management system.

For compliance testing of formations and pavement layers, a tabulated spreadsheet is an effective means of presentation and should include as a minimum:

  • Sample point location by Easting, Northing, Chainage and offset.
  • As constructed elevation and corresponding design elevation.
  • Elevation differences and a status of compliance for each sample point relative to design tolerances.
  • Straight edge delineation's.

In the case of structures and culverts, diagrammatic representations showing the as constructed
dimensions can be an effective means of presentation.

It is recommended that compliance survey observations be conducted at corresponding locations on each respective pavement layer i.e. chainage 13500 o/s 5.0 on sub-grade, sub-base, base-course, and asphalt. A simple reduction of elevations from the previous pavements compliance results at each corresponding location will provide a test for layer thickness in addition to surface level tolerance.

 

8 AUDIT SURVEYS

An audit is the process by which the superintendent satisfies himself that he is actually getting the product specified in the contract. In that sense an audit can be a desktop examination of information supplied by others, or it could be a comprehensive on-site corroboration of the contractors checking team, or some combination of field inspection and verification of contractors' records.

8.1 AUDIT FREQUENCY AND OBSERVATION DENSITY

  • The superintendent's representative should be requesting a minimum level of audit on all survey and construction products and processes. The superintendent's representative will determine if the audit frequency can be reduced or increased depending upon the confidence obtained from the initial minimum auditing regime.
  • Minimum audit can be defined as the minimum survey requirement necessary to establish a degree of confidence that the product being delivered complies with contract specification.
  • Minimum audit may well constitute 100% sampling of the product depending on the origins, however, generally minimum audit is in the order of 5 - 15% of the product being audited.
  • The frequency of product audits will depend upon the confidence obtained from the contractor's compliance test results when compared with audit results.
  • A recommended minimum survey audit surveillance plan is available for reference:

Survey Audit Surveillance Plan


 

8.2 SURVEY CONTROL REQUIREMENTS FOR PERFORMING AUDIT SURVEYS

  • Construction audit surveys shall be conducted using verified primary construction control as supplied at the commencement of the project by Main Roads.
  • Supplementary construction control established by the contractor may be utilised for audit purposes provided it has been verified for horizontal and vertical position relative to the primary control network and the MRWA Survey and Mapping standard 67-08-36 "Road Reference Marks". A minimum of two adjacent control points from the original primary network shall be utilised for the verification.
  • If auxiliary control is required for audit purposes then it shall be established in accordance with the Survey and Mapping specification 67-08-36 "Road Reference Marks" with the exception of its construction. The construction of the control point will be determined by the superintendents representative based on whether its retention will benefit future audit or construction set out.
  • The surveyor will be required to submit in conjunction with the audit results, all field measurements and adjustments pertaining to the verification/establishment of construction control for survey audit.
  • It is recommended verification of observations be an inherent requirement for all construction survey audits.

8.3 SUPPLIED INFORMATION

The following information will be required by the superintendent's representative surveyor to perform survey audits:

  • Construction control coordinates and summary sheets.
  • MX cross section (994 output) and geometric string (992 output) reports.
  • A1 construction drawings
  • MX digital design model (default 081 genio output) if requested.
  • Technical  specification

 
 

 

 

 
 

8.4 SURVEY EQUIPMENT

  • A valid calibartion certificate shall accompany all survey equipment utilised for survey audit and will be made available on request to the superintendents' representative.

8.5 RECOMMENDED AUDIT SURVEY VERIFICATION PROCEDURE

  • Prior to the submission of audit resulst for analysis it is recommended that an overlap section be captured from adjacent control points between observation sets. Common points to both observation sets within the designated overlap area will be measured from each Image4x.gif.GIF
 
Figure 1 - Field Checking procedure for audit measurements
 

8.6 OBSERVATION CONSIDERATIONS

It is ultimately the responsibility of the project surveyor to ensure suitable survey practices are adopted to achieve and/or better the survey accuracies required for each respective survey application.

The following considerations have been supplied as a guide for superintendent representatives:

  • All surveying methods have intrinsic weaknesses and errors. This error is minimised with correct survey practices using appropriate survey instrumentation.
  • It is recommended the following sighting distances using Total Station not be exceeded:

(a)   High precision structures (sub 2mm): 80m
(b)   Pavement formations (incl. asphalt): 130m
(c)   Earthworks: 260m

  • These distances are based on ideal survey conditions when total station observations are able to achieve highest accuracy. The surveyor shall reduce the sight distances accordingly if weather conditions are extreme.
  • All surveying methods have intrinsic weaknesses and errors. This error is minimised with correct survey practices using appropriate survey instrumentation.
  • As a guide for audit measurement, the automatic level and staff should be capable of repeatedly measuring a pavement to 2mm (1mm for structures) for vertical accuracy at the 95% confidence level using SP1 differential levelling techniques. Whereas the 3" total station using the trig heighting method is realistically capable of repeatedly achieving 3 to 5mm for vertical at the 95% confidence level in ideal observing conditions where the distance does not exceed 130m.
  • This error associated with trig heighting can be attributed to instrument or prism pole height error, instrument collimation, poor target bisection and poor target point selection.
  • It is recommended the trig heighting method be used for audit measurement. It provides an acceptable level of accuracy for pavement auditing and is significantly quicker and more efficient than conventional levelling. The error associated with trig heighting can be attributed to instrument or prism pole height error, instrument collimation, poor target bisection and poor target point selection.
  • Technology today enables the uploading of vertical and horizontal design alignments directly into survey instrumentation. This enables instantaneous comparisons of as constructed pavements with design in the field from random sampling. All observations can be referenced to the master alignment by chainage and offset.
  • RTK GPS complies with vertical accuracy for Sub-Grade only. It is not to be used for vertical set out on base course final level and structural set out.

 

8.7 DATA RECORDS AND PRESENTATION

  •  Audit surveys will require the submission of a digital MX genio file together with a tabulated spreadsheet summarising the results in a format stipulated by the superintendents' representative. Additional diagrammatic representation may be required if the tabulated output is inappropriate. A copy of the least squares adjustment is to be included in the quality statement if additional control is established.