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Land Surveying 2 (DE 6207 & ENGG 6207) Lecture 1 NDS & NZDE

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This lecture note gives a detail insight into land surveying. Total page: 102 pages

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Land

Surveying 2

(DE 6207 & ENGG 6207)

Lecture 1

NDS & NZDE

Introduction

Course Details

• Lecturer: David Allen – (Room 114 – 4024 on extn 8641).

• My background & experience in surveying & land development industries, working as a surveyor, an engineer and project manager.

• Values - (Respectful environment, everyone is valued, welcome & encourage your input).

• Working relationship, between you and me

• We want you to enjoy the learning experience, work hard and be successful in your endeavours.

Introduction

Expectations

• 13 weeks course time – mix of theory lectures, field practical components, calculations and written reports, with some revision

• Internal Assessment is a mix of three assignments; two Tests; and a final exam

• Reiterate the importance of completing assignments and practicals.

• 50% internal assessment & tests; 50% external exam

• Attendance & completion of all internal assessment elements is critical to your success.

• Intention to have one or two guest lecturers (TBA), and possibly a site visit.

Land Surveying 2

Aim & Purpose

•To develop further land surveying knowledge, skills & understanding.

Land Surveying 2

Learning Outcomes

• Undertake advanced setting out & levelling techniques

• Demonstrate knowledge of the cadastral survey system and land subdivision process in NZ

• Application of GPS in surveying

• Demonstrate knowledge of survey computations

Land Surveying 2

Course Outline / content / topics • 13 week program (divided by mid-term break in

October)

• Further develop your knowledge of surveying principles and the use of GNSS equipment for different types of survey project. – Working from the whole to the part; error theory; control

networks for engineering projects

• Develop an understanding of survey specialisation in certain areas, (i.e. setting out of complex engineering works; GNSS survey methods; advanced levelling procedures and techniques; & computer applications)

• A mix of lecture (theory), field work elements, self directed learning, assignments and tests

Land Surveying 2

Course Objectives Enable students to gain an understanding of:

• The principles of GNSS measurement, including different measurement modes & techniques

• Advanced levelling techniques, including trigonometric levelling principles

• Gain some hands-on experience using Leica VIVA GPS equipment, as well as digital precise level

Land Surveying 2

Course Objectives (cont) Enable students to gain an understanding of:

• Basic knowledge of 3D reference & measurement surfaces, and the relationship to height values.

• Explain construction methods & associated surveying setting-out techniques used for specific engineering works.

• Outline the land development process from start to finish, including design, costings, compliance.

Land Surveying 2

Course Assessment

Mix of Assignments; Tests & Individual Assessment & a Final Exam (Total 100%)

• Three (3) assignments (50% of total course mark)

– Assign’t 1: a practical field element for setting out and levelling - 20%

– Assign’t 2: A survey computations assignment - 10%

– Assign’t 3: Related to cadastral survey / land tenure aspects - 10%

• Tests (x2) – Duration will be 1.0 – 1.5hr (One Open book & one Closed Book) - (10% of total mark)

• Final Exam – 3hrs duration (on everything covered within the course – (50% of total marks)

Land Surveying 2 - content

• Define the terms “engineering works and engineering surveys”. – What are they? What are the requirements?

• Outline GNSS (for those who are new to this technology). – Principles and techniques

– Accuracy, knowledge of potential errors, equipment constraints, personnel & logistic limitations.

• A quick review / definition of survey reference surfaces & their relationship.

• Levelling techniques (ordinary, precise, & trigonometric heighting).

Land Surveying 2 content (cont)

• Complete a field project (survey set-out of engineering works) to demonstrate understanding of survey practice

• Land tenure systems & interests in land – LINZ role & standards, including a review of Landonline

– NZ land legislation

• An overview of the land development process – Resource Management Act & Land Transfer Act

– A look at the typical subdivision process

– An analysis of subdivision costs, including a case study example

– Infrastructure design requirements

– Compliance requirements

• Survey computations – Areas, resection, intersection, & free station calculations

Land Surveying 2

• Engineering works defined – What do you think they are?

– Mainly concerned with those works associated with civil & structural engineering projects.

– Civil engineering – The design and construction for engineering projects, such as public and private works, such as infrastructure (roads, railways, water supply & treatment etc), pipelines, dams & reservoirs, bridges & tunnels, and buildings.

Land Surveying 2

Engineering surveys

• Engineering surveying covers the detailed surveys required for design of engineering projects (roads, bridges, dams, buildings, tunnels etc) as well as the setting out and monitoring of the subsequent construction or structures.

Construction surveying

• Construction surveying is generally performed by specialised technicians.

• Construction surveyors perform the following tasks:

– Survey existing conditions of the future work site, including topography, existing buildings & infrastructure (including underground infrastructure)

– Construction surveying setting-out: involves staking out reference points & markers that will guide the construction of new structures such as roads or buildings for subsequent construction.

– Verify the location of structures during construction

– As-Built surveying: a survey conducted at the end of the construction project to verify that the work authorised was completed to the specifications set on plans.

Engineering Works

The terms is wide and varied & relates to numerous facets & project types

• Building or construction projects • Relates to specific structures

• e.g. low level; medium to high rise buildings, stadiums; residential buildings; standard & odd shaped structures, etc.

(The list is extensive) • Can include civil structures, (such as bridges, tunnels,

dams, drainage facilities such as treatment plants, pump stations, etc) with significant structural elements involved.

Engineering Works

• Infrastructure projects

• Infrastructure is the basic physical and organisational structures needed for the operation of a society or enterprise, or the services and facilities necessary for an economy to function. (Wikipedia, 2012)

• The term typically refers to the technical structures that support a society, such as roads, water supply, sewers, power grids, telecommunications, and so forth.

Engineering Works

• Infrastructure projects

• Civil engineering projects normally (i.e. motorways & roading projects, bridges, tunnels, rail, drainage & pipeline projects; utility services projects (power, telecoms, gas, water supply).

• Hard Infrastructure: transport, energy, water management, communications, solid waste management, earth monitoring & measurement networks

Building or Construction projects

Building or Construction projects

Building or Construction projects

Building or Construction projects

Hydropolis

Hotel,

Dubai

Building or Construction projects

Sagrada Familia

(Barcelona)

Infrastructure projects

Roading projects

Rail projects

Bridges & Tunnels

Drainage projects

Utility Services

Land Development

The terms land improvement and land development are general terms that in some contexts may include infrastructure. Generally refer only to smaller scale systems or works that are not included under an infrastructure definition, as they are typically limited to a single parcel of land, and are owned and operated by the land owner.

For example, a regional irrigation canal compared to a private irrigation system on an individual land parcel.

Service connections to municipal service and public utility networks would also be considered land improvements, not infrastructure.

Engineering Works

• Land development projects Numerous project types

• e.g. Urban, Rural, Rural-Residential

• (residential, commercial, industrial, recreational),

Differing project & site conditions

• Greenfields

• Brownfields (in-fill development)

• Stratum estates; Apartment developments

• Retirement Villages

• Sporting & Recreational facilities

• Industrial complexes

Land Development Projects

Engineering Works

• Civil construction • Earthworks, dams, roading, harbours, structures

• Special purpose

• Mining

• Energy sector (i.e. hydro-electric, wind, geothermal, petrochemical)

• Structure positioning (e.g. oil rigs, cranes, tunnelling machines)

• Industrial applications (e.g. related to production machinery – aspects of alignment, extension, flatness, uniformity)

• Earth deformation; geotechnical sub-surface movement

Special Purpose Surveys

Mining • Pit and open-cast operations)

Special Purpose Surveys

Energy sector • Hydro-electric; Wind farm; Geothermal; petrochemical

Special Purpose Surveys

Structure positioning • Oil rig location; Mechanical structures

Special Purpose Surveys

• Earth Deformation Surveys • Fault line monitoring, & landslip & subsidence

• Geotechnical sub-surface survey • Sub-surface profiling; piezometer & borehole location, ground

radar surveys, seismic surveys

Engineering Surveys

• Engineering surveys are conducted to obtain data essential for planning, estimating, locating and layout for the various phases of projects.

• The objectives of engineering surveys include obtaining preliminary data required for selecting suitable routes and sites and for preparing structural designs, establishing a system of reference points, and marking lines, grades and principal points.

Engineering Surveys

• Buildings • set-out both horizontal & vertical elements, during

construction; & can include post construction monitoring)

• Industrial applications • Often associated with manufacturing processes

• Deals with issues such as alignment; flatness; truly level surface

• e.g. Pacific Steel Bar mill; F & P crane gantry

• Relative precision a key issue

• Can be high accuracy requirements depending on applic’n (e.g. Pacific Steel bar mill: ±1mm in Z)

Engineering Surveys

• Processing or treatment plants • Similar to industrial applications in some instance

• (i.e. alignment, flatness; etc)

• Asset location fixing (e.g. Watercare); monitoring; quantities

• Infrastructure projects • Numerous project types

• e.g. roading, drainage, utility services, rail,

• Again encounter differing project & site conditions

• Require a good understanding of accuracy requirements, specifications & an understanding of what they actually mean (e.g. Metrowater ICS spec’n)

• (i.e. Fitness for Purpose)

• Access & OSH issues applicable

Engineering Surveys

• Survey Methodologies • As with many surveys, often requires a mix of

instrumentation to achieve end result

• Selection of instrument type critical: ~ to ensure required specification can be met or exceeded.

• Sometimes restricted by what is available.

• Check project brief for relevant accuracy specifications & other data

• Relevant checks & Q.A • Depends on survey requirements

• Must be able to determine if specification has been met

• Redundant observations & suitable checks onto known points

Engineering Surveys

Principles of Surveying

There are a few rules that apply to all categories and whenever field work is being carried out & should be adhered to at all times.

Worthwhile reiterating these again. 1. Working from the whole to the part

• One of the underlying principles of surveying (i.e. working within a framework of established points to “fix” points that are unknown)

2. Accuracy • Use of instruments to measure angles, distances and level

(requires techniques & procedures to be mastered)

• Important to realise that Absolute precision can never be obtained, despite ideal conditions and the use of the best equipment & techniques

Principles of Surveying

3. Errors • Much of what is done in surveying is prone to errors

• Gross (mistakes), systematic & random (unavoidable)

• Mistakes arise from inattention, inexperience and carelessness. Important to adopt procedures or independent checks that eliminate or isolate such errors.

• Systematic errors are those which may exist but whose pattern and effects are known, can be monitored and compensated for by applic’n of appropriate corrections. (e.g. EDM distance; - also measure temp & pressure)

• Random errors are unavoidable & due to imperfections in instruments used, human elements such as eyesight, & inconsistent conditions that cause such errors.

Principles of Surveying

4. Survey methods

• Surveys can usually be executed in several ways by a combination of instruments and methods. Main factors to consider when deciding upon technique to be used:

Purpose & extent of the survey

Degree of accuracy required

Control of errors

Nature of the country (i.e. topography, vegetation, visibility & access issues, etc)

Commercial issues (i.e. budget & programme considerations)

Principles of Surveying

5. Good survey practice (As a general guide)

• Use equipment which is well maintained, regularly checked and “calibrated”

• Analyse acceptable error limits for each component of the survey (i.e. set the target accuracy specification)

Be aware of likely error sources; resolve existing & underlying errors (don’t introduce new ones)

• Conform with defendable marking, measuring, recording and processing methods.

• ALWAYS take check (‘redundant’) measurements.

• Be careful & objective when collecting, assessing and recording measurements & data, & while documenting and analysing results

• (Don’t cook the books!!)

Land Surveying 2

Exercise ~ What is the difference between how engineers

& surveyors perceive the requirements for surveying on engineering projects?

~ Split into 2 groups (5 to 10 minutes), discuss, formulate opinion & then report to the class.

47

BREAK

Survey Control Networks

A control network is a set of

reference points of known

geo-spatial coordinates.

The higher-order control points

are normally defined in both &

time using global or space techniques, & are used for lower order points to tie into.

Survey Control Networks

The discipline that deals with the

establishment of coordinates of

points in a higher order, control

network is called geodetic

surveying.

A control network is normally

divided into horizontal (X & Y) and vertical

(Z) controls, but with the advent of GPS, this division is becoming obsolete.

Survey Control Networks

Control networks provide a reference framework of points for:

1. Topographical mapping & large-scale plan production.

2. Dimensional control of construction work.

3. Deformation surveys for all manner of structures, both new & old.

4. The extension & densification of existing control networks.

Control Networks

In general & in relation to engineering projects

• A survey control system (network) consists of physical control marks, often with beacons to promote remote access to a network.

• Traditional networks of control marks consist of a hierarchy of marks based on accuracy (called orders).

Control Networks

In general & in relation to engineering projects

• The NZ geodetic system enables consistent spatial positioning (X,Y & Z) across the country, playing an important role in the development of our country.

• The geodetic system includes the control system, geodetic datums, vertical datums, projections & other information used to define a nationally consistent reference frame.

Control Networks

In terms of NZ national control

system, the most accurate control

marks are Order 0 (are also CORS

stations i.e. GNSS Continuously

Operating Reference Stations).

There are 33 CORS stations in total

(PositioNZ network)

Several of the PositioNZ station are also International GNSS Service (IGS) sites.

Control Networks

• Enhancements to the PositioNZ network, such as the provision of real-time data in being considered.

• Connects NZ to Global Reference systems, ensuring that NZ geodetic system is comparable with international systems.

Control Networks

• This control network is being continually upgraded and extended to meet increased accuracy requirements and to meet the needs of an increasing range of users.

• Measuring and mapping continues today, with the management of our natural and economic resources becoming increasingly dependent on the availability of accurate and consistent spatial geographic information.

• Require an accurate spatial reference system, being the NZ geodetic system.

NZ Geodetic Datum 2000

(NZGD2000) • Is the official geodetic datum of NZ & its offshore

islands (implemented in 1998, replacing NZGD1949).

• It is a three-dimensional semi-dynamic datum (i.e. positions described by coordinates in terms of latitude, longitude, and ellipsoidal heights).

• Uses a “deformation model” to correct coordinates and survey observations for the effect of regional-scale tectonic movements.

• NZGD2000 is essentially coincident with World Geodetic System 1984 (WGS84), being the reference system used by GNSS receivers.

• Accuracy defined by a series of

‘ORDERS’ classifications.

NZ Geodetic Datum 2000

(NZGD2000)

Name New Zealand Geodetic Datum 2000

Abbreviation NZGD2000

Reference Ellipsoid GRS 80

Reference Frame ITRF96

Reference Epoch 01 January 2000

Deformation Model LINZ deformation model

NZ Geodetic Datum 2000

Relevance

The network forms the basis for geodetic networks within all the meridional circuits (e.g. Mt Eden 2000)

NZTM2000 uses a Transverse Mercator projection and is based on the NZGD2000 datum using the GRS80 reference ellipsoid.

Many engineering projects require survey networks to be established in terms of such localised reference datums (e.g. NZTA projects, Watercare projects, etc).

Vertical elements usually in terms of a Local Vertical Datum (LVD) or NZVD2009

Final as-built certification values usually

required in terms of local projection.

Control networks for engineering sites

General Principles

• A control survey provides a framework of survey points, whose relative positions (2D or 3D) are known to specified degrees of accuracy (Schofield &

Breach, 2007)

• Areas covered:

• Whole country as basis for national maps

• Smaller areas, encompassing a construction site

• Must work from the “whole to the part”

• Preservation of precision important.

Control networks for engineering sites

General Principles (cont)

• Important to understand the project specifications (what do they actually mean?)

• How precise & reliable does the survey control need to be?

• Specification limits will also determine instrumentation requirements & appropriate survey methodologies.

• Horizontal and vertical elements should be considered separately. They will utilise different origin datums.

• Control networks will usually be specific to the engineering project concerned. Common for them to be in terms of local external systems.

Control networks for engineering sites

General Principles (cont)

• Remember, a survey is designed for a specific purpose, so that a technical and commercial objective can be achieved at minimum cost.

• Questions to be answered:

1. What is the survey for?

2. How extensive does it need to be?

3. What are the budgetary & programme constraints exist? (i.e. commercial factors)

4. With logistical constraints in mind, where is it?

5. How precise & reliable does it need to be?

• Faulty set-out causes loss of time & money in corrective work.

Control networks for engineering sites

Adjustment of Control Networks

• Necessary for all site specific control networks to be properly adjusted. (Depends on req’ts).

• Remember – adjustment it is not simply a means of getting rid of gross errors in the observation phase.

• Methods on larger projects usually RIGOROUS. • i.e. Least squares estimation technique (statistical

probability analysis that details precisions/accuracies)

• Important to understand what accuracies are achieved in the control network, to ensure that set-out accuracies & tolerances can be met • (i.e. working from the whole to the part)

Setting out (definition)

• Setting out is the establishment of marks & lines to define the position & level of elements of the construction work so that works may proceed with reference to them. This process may be contrasted with the purpose of Surveying which is to determine by measurement the positions of existing features. (ISO_7078: 1985 Building Construction – Procedures for Setting out, Measurement & Surveying – Vocabulary & Guidance Notes.)

• Alternate definition is that setting out is the reverse of Surveying. (i.e. surveying is a process of producing a plan or a map of a particular area, setting out begins with the plan and ends with the various elements of an engineering project correctly positioned in the area. (Uren, J. et al 2006).

Setting out (definition)

• Attitudes to setting out vary from site to site, with generally insufficient importance attached to the process.

• It tends to be rushed (time constraints & pressure from contractors), often leading to errors & in some cases resultant costly corrections

• Good work practices & techniques in setting out essential to minimise errors & to ensure the construction process proceeds smoothly.

• Good knowledge is vital, as the setting out phase is one of the most important stages in any civil engineering construction project.

Setting out (AIM)

• The aims of setting out are to position the works in their correct relative spatial and absolute positions, & to ensure that they proceed smoothly and that their costs are minimised. (Uren, J. et al 2006)

• Chances of this aim being achieved will be greatly enhanced by the use of suitable control methods, availability & reference to correct plans, and where good working practices are adopted.

Setting out (AIM)

Two main aims:

1. Various elements of the scheme must be correct in all three-dimensions both relative and absolute (i.e. correct size, plan position & reduced level).

2. Once set-out begins, it must proceed quickly & with little or no delay so the works can proceed smoothly and costs can be minimised.

Note* - worth remembering that the construction contractor’s main commercial purpose is to make a profit, & hence efficient setting out procedures will help this be realised.

Setting out (dimensional control)

• In engineering, first step in the planning and design of a construction project is the production of an accurate scaled plan.

• Thereafter, the project, designed in terms of this plan, must be set-out on the ground in correct absolute and relative position, & to its correct dimensions.

Setting out (dimensional control)

• 3D survey control planned with the setting out (& monitoring & compliance elements) in mind & control stations conveniently sited accordingly • (i.e. to facilitate easy, economical set-out).

• Control marks placed must survive the construction processes (i.e. stability, permanence, reliability).

Setting out (dimensional control)

• A complete & thorough understanding of the plans, setting out data, tolerances, & the time scale of operations is imperative. • Make sure you are working off the current set of design plans

& calculations data !!!!

• Surveyors should be proficient in AutoCAD.

• enables data manipulation prior to bringing into survey package.

• Have a sound working knowledge of the survey instrumentation available, including the effects of instrumental errors on setting-out observations. • Select the right instrument(s) for the project.

Setting out (dimensional control)

General Principles

• Points of known plan position must be established within or near the site from which the design points can be set out in their correct plan positions (i.e. involves horizontal control techniques)

• Points of known elevation relative to an agreed datum are required within or near the site from which the design points can be set out at their correct reduced levels. (i.e. involves vertical control techniques).

• Accurate methods must be adopted to establish design points from this horizontal and vertical control. This involves positioning techniques.

Setting out

Most important aspects • Making sure that the data provided to you is

suitable for set-out, so check this in the office prior to going to site.

• Understand the importance of completing independent checks on computations, set-out data extrapolation & actual setting out procedures.

• You will sleep better at night when you complete your checks.

• Remember: if it doesn’t look right, then review & recheck it. Don’t just proceed.

Planning & layout of survey control

Building construction

1. Small scale buildings (i.e. residential, commercial)

• Building dimensions usually obtained from architects plans. Always CHECK them – they are often incorrect.

Planning & layout of survey control

Architects plans

Planning & layout of survey control

Building construction

1. Small scale buildings (i.e. residential, commercial)

• Individual building corners, or specific foundation positions (piles), set-out from known control. – (i.e. bearing & distance to each corner). Usually in X & Y only.

– GPS or total station techniques (GPS suitable for X & Y only)

• Perpendicular offset methods can be used

• Height value obtained when set-out peg has been placed, and then used as a height reference (or use separate BM)

– Height control normally achieved via standard levelling techniques, to achieve required accuracy.

Planning & layout of survey control

Building construction

1. Small scale buildings (i.e. residential, commercial)

• Importance of checking right angles & cross-dimensional angle and distances – (i.e. nothing is ever square when set out from a single point).

• Corner markers can be offset if required. – Initial foundation excavation will likely destroy the set-out mark as

placed

– Always discuss with the building contractor (what do they need?)

– Builders still use stringlines, via profile boards

• Alternative: – set-out marks on builder’s profiles.

• Check offsets to boundaries – Verify location of building on the site

– Check any HIRTB requirements

Planning & layout of survey control

Building construction

1. Small scale buildings (i.e. residential, commercial)

Planning & layout of survey control

Building construction

2. Large buildings (i.e. industrial, medium & high rise)

• Important for the surveyor to liaise with architects, structural & civil engineers involved (where appropriate), & the site foreman.

• Set out data must be consistent from all sources; must be the latest version & suitable for setting out purposes. Everyone must be working from the same set of plans or data.

• Accuracy can be achieved in a variety of ways, using different instruments. Accuracy specs sometimes dependent on construction method – (e.g. precast panels, therefore requires tight tolerance)

Planning & layout of survey control

Building construction

2. Large buildings (i.e. industrial, medium & high rise)

• Survey control can (& often is) site specific, not connected to a wider control network

• Can be achieved using building coordinates, specifically setting-out individual corners or columns, foundation piles, or services.

• Extended baselines can be utilised where building profiles or stages extend over distance.

– (e.g. retirement village complex).

• Via the building (structural) grid system. These are coincident with the structural (column) elements & form the basis for multiple level construction.

• Legal boundary issues must be considered.

Planning & layout of survey control

Building construction

2. Large buildings (i.e. industrial, medium & high rise)

• On medium and high rise structures, verticality & height transfer from level to level is an issue, and as such must be checked at every floor.

• Various techniques to achieve this. – Conventional levelling using precise methods & equipment

– Trigonometric heighting (requires room to make the observations).

– Direct optical (vertical) transfer at building corners • (i.e. optical or laser plummets)

– Precise GPS (RTK) techniques to plumb building columns. Larger high rise buildings are now incorporating inclination sensors to monitor building deviation (corrects for displacements due to tilt, contraction & expansion, as well as wind).

• Case studies (IBM House, & Skytower).

Planning & layout of survey control

IBM House, Auckland CBD. (5-storey medium rise building; 2 parts to the bldg design.)

– Grid system for horizontal control, on the alignment of the main columns. (Site control network only, not linked to outside control).

– Heights in terms of local AK MSL 1946 datum; (site BM required).

– Instrumentation: Standard precision theodolite, right angle eye-piece for vertical alignment facet; ordinary Leica level for height control.

– Trigonometric heighting & standard levelling used for height control

– Floor by floor construction, reinforced concrete structure.

– Column lines setout & alignment extended onto adjacent bldgs.

– Grids transferred floor by floor,(became more difficult with height).

– Distances setout using EDM & calibrated steel band.

– Time pressures the norm (setout just ahead of construction)

– Heaps of independent checks !!!

Planning & layout of survey control

Auckland Skytower, Auckland CBD. • Construction is reinforced concrete;

type of slip-form formwork.

• Unique survey methodology; (precise tolerances)

• Close relationship with technology suppliers &

international experts.

• Challenging site conditions (high risk; complex).

• Contract had tight timeframe (penalties?) so

surveyors on call 7 days a week (2.5 yrs).

• External control system for horizontal control.

• Alignment control; direct measurement

from external locations; GPS meas’t &

direct vertical alignment observation.

• Account for building sway (up to 1m)

• Control points located on adjacent

high rise structures (e.g. ASB Tower).

Planning & layout of survey control

Infrastructure projects

1. Roading highways or motorway projects

• Numerous elements to consider.

– Earthworks; roading alignments (H & V); drainage elements; retaining structures; bridges & tunnels; services locations; as-builts; monitoring; legal boundary elements;

– Often high risk environments for the surveyors (due to construction machinery; proximity to existing live road environment).

• Huge OSH requirements (Site Induction, Site Safe passports)

– Starts with surveyor accepting data design in electronic format to load into instruments.

• Data can be manipulated to suit (i.e. offsets & height adjustments).

• Proprietary packages assist process

Planning & layout of survey control

Infrastructure projects

1. Roading highways or motorway projects

• Numerous elements to consider.

– Survey control needs to account for all facets of the project (i.e. relative accuracy spec set appropriately; - usually defined at contract tender stage with reference to NZTA survey stds document).

– Set-out methods need to be adaptive to the conditions. • Get the maximum benefit out of the equipment available

– Alignment corridors long and narrow; survey controls designed to fit the specific environment

– Communication!-(working with the contractor, engineers etc).

– Contractors often have their own surveyors

Planning & layout of survey control

1. Roading highways or motorway projects

Planning & layout of survey control

1. Roading highways or motorway projects

Planning & layout of survey control

Roading highways or motorway projects

Numerous elements to consider. • Main survey control marks located outside construction zone, along full

length of the project; utilises existing LINZ control marks where available as the basis for the control network. (requires search of LINZ geodetic database form control framework).

• Main marks need to be protected during project duration. Costly & time consuming to replace (possibly delays).

• Control network observed with a mix of GPS, total stations & precise levelling methods. Normally adjusted using rigorous method

– (i.e. Least squares estimation technique).

• Internal set out marks required (temporary in nature)

• Setouts include: horizontal & vertical positioning for roading centrelines, kerb lines, centre islands, barrier locations; retaining walls, bridge piers & alignments; formwork locations; drainage locations (cesspits, culverts, etc); lighting; signage;

Planning & layout of survey control

Infrastructure projects

2. Urban & rural roads

• Network required to cover entire project.

• Different levels of control & set-out for each – OSH requirements (roading environments are dangerous)

– horizontal & vertical elements (local coordinate & height systems)

– Contract documents usually specify accuracy requirements.

– Necessary to work closely with the contractor

– Again set-out requirements linked to the nature of the work • Centrelines, kerb & channel alignments; cesspits & culverts; embankments &

any retaining structures; specific detail at intersections.)

– On rural roads, contractor can usually interpret from centreline positions only.

Planning & layout of survey control

Infrastructure projects

1. Drainage projects

Planning & layout of survey control

Earthworks construction projects

1. Conventional methods

• Staked set-out for bulk earthworks sites. – Cuts or fill measurements marked on stakes.(Sometimes colour

coded for cut or fill).

– Stakes left on small mounds, with earthworks going on around them.

– Mark out the perimeter (edge) of the excavation; (i.e. site rail level)

– Regular survey undertaken to monitor progress & to reinstate visual markers for the contractor (time consuming & costly).

– Stake markers often destroyed, as they were needed in the construction zone.

– Spray marks on the ground sometimes used to mark works limit, or to indicate cut or fill depths

– Achieved construction precision not great; often required rework

– More precise works - greater surveyor input

Planning & layout of survey control

Earthworks construction projects

2. Machine guidance & machine control

• The use of GPS, Total Stations or Lasers technology to

guide or control agricultural, construction and mining

machinery.

• Accurately guiding, positioning or controlling the machine

can significantly improve accuracy, and productivity as well

as reducing operational costs. (Global Survey, 2011).

• Machine Guidance vs. machine control

– Guidance is the where the operator fully controls the machine, and

they receive visual indications and prompts from the system

– Control is where the system provides full hydraulic control

• Guest lecturer (Ray Copeland, 10 August

MD for Global Survey Ltd, NZ)

Machine Control

Planning & layout of survey control

Industrial applications

1. Manufacturing / processing

• High precision / accuracy the norm • Flatness, alignment, orientation; position

• Linked to manufacturing processes,

or machinery installation. – E.g. kiln alignment; power generator positioning; satellite dish

position and alignment

• Instrumentation choice & methods used are critical. – Accuracy usually the key aspect (right first time imperative)

– Localised control if any. Usually related to position of other plant

– Confined space & working environment aspects to consider

• Examples: – F & P crane rail; Genesis Huntly generator;

– Waihi Gold Mine conveyor setout

Good working practices when setting out

1. Keep careful records

– Neat & tidy records (field books, sheets, digital files).

– Note any that had an influence on the works.

– Can be used as evidence in any dispute

2. Adopt & implement sensible filing procedures

– Quantum of field records & setting out documents grows quickly as project proceeds.

– Often only record of particular activity (i.e. evidence)

– Important that they are carefully stored (i.e. safe & easily retrievable).

– Records properly & adequately labelled and marked

Good working practices when setting out

3. Care of instruments & safe use

– Look after the tools of the trade (i.e. care of equipment imperative. Instruments kept adjusted, calibrated & in good working order).

– Transported correctly (in the vehicle & in the field)

– Consequences of loss of time due to badly adjusted or damaged instruments can be serious (i.e. construction plant & workers kept idle; programme delays; wastage of

materials). Time is money !!

4. Check the drawings / plans

– Essential that you have the correct information at hand.

– Check them for consistency & completeness

– Drawing versions are current

Good working practices when setting out

5. Walk the site

– Initially walk the whole site & carry out reconnaissance.

– Must be familiar with the area (cannot do this from inside the office).

– Note any ground surface problems, & discrepancies between the site & the drawings to be reported.

– Inspect the site regularly (i.e. missing or damaged control or set-out points; carry out checks where necessary)

6. Work to the programme

– Be familiar with the works programme.

– Plan setting out operations in advance

– Execute them on time to prevent delays

– Agreed changes to be immediately recorded

Good working practices when setting out

7. Work to the specifications

– Contract documents specify required tolerances for different setting out operations.

– Adopt suitable equipment & techniques to meet spec’ns

8. Maintain accuracy

– Working from “whole to the part” principle should apply.

– In practise this means that all design points must be set out from control framework.

– This approach avoids any compounding errors.

Good working practices when setting out

9. Check the work

– Each setting out operation must incorporate a checking procedure.

Golden Rule: work is not completed until checked.

– Checks must be independent of the initial method used (e.g.).

• Points fixed from one position checked from another

• Critical points may require a third check.

• If all four corners of a building have been established, the two diagonals should be measured and checked.

• Use correct (closed loop) levelling procedures to known RL pts.

• Once distance has been set out, it should be measured twice as a check. Measured in both directions if possible.

Good working practices when setting out

10. Communicate

– Lack of communication is one of the main causes of errors on construction sites.

– Essential to understand what is to be done before proceeding with the task.

– Verbal comm’n acceptable in most cases, however for matters which may be disputed .. requires confirmation in writing

– Errors reported as soon as discovered.

– Nothing to be gained trying to hide errors. Prompt action may save considerable amount of money.

Developments in surveying technology

Towards integrated surveying

• Major advances in recent years • total stations, satellite and airborne surveying systems,

data collection & data communication aspects, software

• Trend towards “integrated surveying”. • System made up of:

– A surveying sensor (instrument) - (e.g. total station, GPS receiver, laser scanner, digital level)

– Data collection hardware & software

– Data communications

– Processing & design software

Developments in surveying technology

Towards integrated surveying

• In practical terms, it means that all surveying instruments (sensors) will be interchangeable & data flow across all surveying disciplines will be seamless. (Uren & Price, 2006).

• For example, data from control survey, acquired by GPS, then transferred directly on site to a total station or laser scanner for mapping purposes.

• Several instruments involved; but each dataset combined by one software application to produce a map, DTM or plan.

Developments in surveying technology

Towards integrated surveying

• Predicted that sensor technology will continue to improve.

• Especially laser scanning & systems based on airborne mapping

• Advancements in wireless communications

• Mobile (cellular) phone technology – increasingly important

• Significant changes to GNSS systems • new players; signal modifications

• Proper data integration will enable surveyors & engineers to combine all kinds of data & information, without complicated conversions & data loss.

Engineering surveyors role in the future?

• Still requires the ability to observe and measure angles, distances and heights using fairly basic equipment • Conventional theodolites, steel tapes, std levelling equipment

• Retain the ability to use a calculator & process observations by hand

• Construction phase .. Most of time in engineering surveying involves setting out work.

• Is the practical application of routine survey techniques to construction, & requires knowledge of these. • Such knowledge obtained through training & practical experience

• Surveyor needs to understand best methods for specific aspects

• Engineering surveyors also involved to improve data integration (i.e. data managers, that oversee the continuous acquisition, processing & transfer of data between site & office)