UNIT 5 SETTING OUT OF WORKS & MODERN FIELD SURVEY … · 1.3 Control for setting out 1.3.1...

UNIT – 5

SETTING OUT OF WORKS & MODERN FIELD

SURVEY SYSTEMS

R.T.U KOTA / G.I.T JAIPUR SUBJECT – Surveying (3CE4-05) CIVIL ENGG./ III SEM

PRATEEK SHARMA1

Blown up Detail

1.1 Introduction

1.2 Aims

1.3 Control for setting out

1.3.1 Horizontal Control

1.3.2 Vertical Control

1.4 Setting out of Building

1.5 Setting out of Culverts

1.6 Introduction of E.D.M

1.7 Principle of E.D.M

1.8 Measurement of distance

1.9 Introduction of Total Station

1.10 Parts of Total Station

1.11 Advantage of Total Station

1.12 Application of Total Station

1.13 Disadvantage of Total Station

R.T.U KOTA / G.I.T JAIPUR SUBJECT – Surveying (3CE4-05) CIVIL ENGG./ III SEM

PRATEEK SHARMA2

1.1 Introduction

R.T.U KOTA / G.I.T JAIPUR Surveying (3CE4-05) CIVIL ENGG./ III SEM

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• Setting out is the process of transferring the distance from the plan already

prepared, to the ground before starting a construction.

• The plan as designed and prepared is set out on the ground in the correct position.

• The branch of surveyingdealing with the setting out on the ground is known as

construction surveying.


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1.2 Aims

-Understand the roles of the various different types of personnel who are involved in the

setting out process.

-Understand the aims of setting out

-Refer to the different types of plans that may be used in the setting out process

-Appreciate the good working practices that should be undertaken in order that the aims

of setting out can be achieved

-Understand the procedures required to ensure that the horizontal and vertical control

requirements of setting out operations can be met

-Set out design points on site by a number of methods

-Apply horizontal and vertical control techniques to second-stage setting out operations

-Appreciate the application of laser instruments in surveying and setting out


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1.3 Controls For Setting Out

The setting out of work required the following two controls:

1. Horizontal control

2. Vertical control


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1.3.1 Horizontal control

• It consist of establishing reference marks of known plan positions from which

horizontal distances are measured for setting out.

• The control points are generally used to establish a base line near one face of the

structure.

• The setting out is done by taking measurements from the base line.

• Horizontal control can be achieved by establishing reference grid.

• The grid which is used for actual setting out of the salient points of the structure.

• The primary control points may be the triangular stations.

• The secondary control are referred to these primary control stations.


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Fig. Primary and Secondary control Points


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1.3.2 Vertical control

• It consist of establishment of reference marks of known elevation relative to some

specified datum.

• All levels at the site are normally reduced to a nearby bench mark, usually known

as Master Bench Mark(MBM).

• This Master Bench Mark(MBM) is used to establish a number of Temporary Bench

Mark(TBM).


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1.4 Setting out of Buildings

The foundation plan of the building is usually supplied or it can be prepared from the

given wall plan of the building and size foundations for different wall.

Setting out of a building involves the transfer of the foundation plan frim paper into the

actual size.

The object of setting out a building is to provide the builder with clearly defined

outlines for excavations.


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The equipment required for the job are:-

• A 30 m steel tape

• Two metallic tapes (15 m or 30 m)

• A long cord

• A plumb-bob

• Stakes or pegs

• Nails

• A hammer


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• It is of litter use to set the pegs or stakes at the exact position of each of the

corners of the building as they would be dug out while excavating the foundations.

• It is therefore advisable to first set out a reference rectangle either out side the

limits of the excavation or along the centre lines of the outside walls of the building

and then to locate each centre by means of co-ordinates with reference to the

sides of this rectangle.

• Both the methods of forming reference rectangle and setting out the building are

described below.

● Method(1):-Setting out building by circumscribing rectangle

● Method(2):-Setting out building by centre-line-rectangle

Method(1)

By using a Circumscribing Rectangle:

Since stakes cannot be set at the exact corner points of a building, these are set at the

corners of a bigger rectangle circumscribing the actual building. Any suitable distance of

the outer rectangle from the building can be chosen, but a distance of usually 2 to 5 m is

considered to be ideal. The actual procedure consists of the following steps :

Procedures:

Preparation of the foundation trench plan showing the width of the foundations

for various walls.

• Temporary pegs are driven at the actual corner points of the foundation plan.

• Then using these pegs as reference, a parallel line, say PQ of required length is

set out at a arbitrary selected distance from the actual centre line.

• A cord is stretched between the pegs P and Q. At P, a line is set out

perpendicular to PQ.On this line, the position S is marked by setting a peg.


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Step (4) is repeated at point Q so asto obtain point R.• Having now set out the referencerectangle PQRS, the actual cornerscan be marked using the sides of thereference rectangle PQRS.• Once all the points are staked, acord is passed around the peripheryof the rectangle and the actualexcavation lines are marked usingline.Checks :

In steps (4) and (5), after marking

points S and R, respectively, the

diagonals QS and PR should be

measured. These lengths should

correspond to the distances on the

plan.

In this method rectangle formed by the centre lines of the outer walls of the building is

used.

Procedure

• The reference rectangle formed by centre lines of the out side walls of the building as

shown in fig. Is known as centre line rectangle. The corners are located by measuring

their co-ordinates with reference to the sides of this rectangle. The temporary stakes are

fixed at these points.

• By using these stakes, the position of any point can be obtained by plotting its

coordinates using the reference stakes.

• In case of precise working i.e. For important building, a theodolite should be used for

setting out right angles.

• Bench marks should be established in convenient positions away from the site of work so

that they remain undisturbed until the work is completed.


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Method(2):- By using centre-line-rectangle


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a) Setting out of culvert involves locating the corners of the abutments and the spring

walls with respect to the respective centre lines of a road or railway and the

drainage nullah, stream, etc.

b) While designing the culvert, the designer uses these centre lines as axes of coordinates

and their point of intersection is taken as the origin. A detailed tracing of

the plan shows the co-ordinate of the corners of abutments and the wing walls in a

tabular form.


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1.5 Setting out of Culverts


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Setting out a culvert is simple because there is only one span and the flow of

water is less.

If the flow of water is more, it can be easily diverted.

For bridges, flow of water can not be diverted and length may be very long.

Due to above reasons, the setting out can not be carried out from the centre of

the bridge. So, it is not easy to setting out bridges.

• Method of measuring distance between points electronically by using electro magnetic

waves (Infra red, Micro waves etc.)

• Microwave requires transmitters/receivers at both ends.

• Infra red use a transmitter at one end and a reflecting prism at the other end

(Most commonly used).

• EDM devices are typically mounted on top of a theodolite, but can directly mounted

onto a tribrach.

• For Eg. Total Station is a combination of theodolite with built in EDM and

Microprocessor.


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1.6 Introduction of E.D.M

1.7 Principle of E.D.M

EDM is very useful in measuring distances that are difficult to access and are long

distances.

It measures the time required by a wave to be sent to a target and reflect back.


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1.8 Measurement of distance

• Two Methods

• 1. Pulsed laser system

• 2. Phase shift Method (Most commonly used)

• Pulsed Laser System

• Make uses pulses derived from an infra red/ visible laser diode.

• Distance is obtained by measuring transit time and velocity of pulsed electro

magnetic signal in travelling between TS & target and back

• Velocity V of pulses gets determined.

• Transit time t is measured using electronic signal processing technique.

• Distance, D = 0.5 * V * t

• Large no. of pulses gets analyzed during measurements


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• PHASE SHIFT METHOD

• Uses continuous EM waves.

• Measures length by indirectly determining the number of full and partial cycles

of transmitted E M between the two ends of a line.

• EDMI (Electronic Distance Measuring Instrument) consisting of an electro

wave generator, an oscillator, a modulator, a transmitter, and a receiver etc..

• Modulated EM Wave is transmitted to the target , Placed at the other end of the line.

The target, acting as a reflector, reflects the light beam back to the receiver , where the

incoming light is converted to an electrical signal. A phase comparison is made between the

projected and reflected signals. Then the amount by which the transmitted and received

signals are out of phase gets measured electronically and get registered in a meter by getting

converted to an equivalent distance.


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• An electronic / Optical Instrument.

• An electronic theodolite having optical telescope integrated with EDM (Electronic

Distance Meter) and Microprocessor with memory unit and other accessories

• Accessories consists of Keyboard , Display , Power Supply, data collectors, field

computers, memory card etc…

• Provides (By measuring or estimating)all parameters (Distances &Angles) & derived

values(corrections & cordinates) of surveying simultaneously.

• Values of parameters can get displayed in viewing panel

• Precision may vary from 0.1” to 20”.




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• TOTAL STATION TYPES

• Based on minimum circle reading accuracy :

0.1” to 20” (For eg: 1” total station, 2” total station, 5”, 15” , 20” etc..)

• Based on Control

• Manual

• Robotic : (Operator controls from distance via remote)


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1.10 PARTS OF A TOTAL STATION


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1.10 PARTS OF A TOTAL STATION


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SCREEN AND KEYS


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WORKING OF SALIENT PARTS

• Handle : To carry the Instrument physically

• Bluetooth antenna : To communicate via Bluetooth wireless

technology

• External interface hatch : To connect to external devices

• Instrument height mark : To measure height of Instrument

• Luminance sensor : Adjusts the brightness of screen automatically

• Guide light : To carry out setting out measurement effectively

• Objective lens :

• Laser pointer function : To sight a target in dark location

• Vertical clamp screw :

• Vertical fine motion screw


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Trigger key: To carry out operation indicated by the soft key in bold type on the screen

• Horizontal clamp screw:

• Horizontal fine motion screw:

• Tribrach clamp: clamp the upper part of the instrument with lower part

• Telescope eyepiece screw:

• Telescope focusing ring:

• Sighting collimator : To aim in the direction of measurement point

• Instrument centre mark


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• A Total Station primarily consist of an electronic theodolite, an EDM,

Microprocessor and many other accessories.

• Body of a theodolite is divided into two broad parts, upper part –The Alidade &

lower part – The Tribrach

• Alidade includes standards, telescope,EDM, Circles (horizontal &

vertical) and other elements for measuring angles and distance.

• Tribrach contains foot screws, circular level, clamping devise and treads.

• Objective lens : focus on the object to form image at the plane of reticle

• Eyepiece lens : focus on the plane of reticle

• Axis or line of sight : Line joining the objective lens and the eyepiece lens.

• Parallax : If there is relative motion between Image formed & reticle, parallax is present

which should be avoided.

• Lock & tangent screws for revolutions & rotations.

• AUTOFOCUS

• It makes the telescope focus automatically to target. After aiming the telescope to the

target., autofocus button gets pressed


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• TELESCOPE


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ANGLE MEASUREMENT SYSTEM

• For horizontal angle measurement, two glass circles within the alidade are mounted

parallel one on the top of other , with a slight spacing between them. In a levelled TS

(Total Station) horizontal angle circles should be in horizontal plane.

• For vertical angle measurement, two more glass circles are mounted in parallel with

slight spacing between them but aligned in a vertical plane automatically in a levelled TS.

MICROPROCESSOR

• Controls , measures , computes , Reduces observations/ data by providing commands

through keyboard.

• Some salient functions.

• To make circles zeroed instantaneously.

• To observe angles by method of reiteration in either direction.

• To observe angles by method of repetition.

• Averaging multiple distances and angle observations.

• Reducing slope distances into horizontal & vertical distances.

• Computation of elevation from vertical distance components.

• Computation of coordinates from horizontal angle and horizontal distance components.


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1.11 ADVANTAGES OF TOTAL STATION

• Quick setting of the instrument on the tripod using laser plummet

• On-board area computation program to compute the area of the filed

• Local language support

• Full GIS creation

• Automation of old maps

• Greater accuracy in area computation

• Graphical view of plots and land for quick visualization

• Integration of data base

• The area computation at any user required scale

• Once the field jobs are finished , the map of the area with dimensions is ready

instantly after data transfer.

• It reduces the time taken for the survey considerably and it also able to measure

up to 3 to 5 km distances.

• Comparatively easy to work with High precision.


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1.12 APPLICATIONS OF TOTAL STATION

• To measure horizontal and vertical angles

• To obtain the horizontal distance, inclined distance and vertical distance between

points.

• To get the three-dimensional co-ordinates i.e.[x,y,z] of a point in space.

• To find the length of a missing the line

• To find the elevation of the remote object.

• To find the distance to a remote object

• To locate the points at a predetermined distance along gridlines.

• Calculation of Area of a closed figure.


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• Total station is extensively used in Mine Survey, Cadastral Survey, Engineering

Survey, Large scale Survey, Road / rail/ canal Survey.

• Some total stations also have a GNSS (Global Navigation satellite System) interface

which combines the advantages of these two technologies (GNSS – line of sight not

required between measured points; Total Station – high precision measurement

especially in the vertical axis compared with GNSS) and reduce the consequences of

each technology’s disadvantages (GNSS – poor accuracy in the vertical axis and lower

accuracy without long occupation periods; Total Station requires line of sight

observations and must be set up over a known point or with line of sight to 2 or more

points with known location).


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1.13 DISADVANTAGE OF TOTAL STATION

• It may be difficult for the surveyor to look over and check the work while surveying.

• The instrument is costly. And for conducting surveys using Total station, Skilled

personnel are required.

• For an over all check of the survey, It will be necessary to return to the office and prepare

the drawings using appropriate software.

• The instrument contains sensitive electronic assemblies which have to be well protected

against dust and moisture

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UNIT 5 SETTING OUT OF WORKS & MODERN FIELD SURVEY … · 1.3 Control for setting out 1.3.1...

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