Surveying Principles and Scales

GLOBAL INSTITUTE OF TECHNOLOGY
JAIPUR
BASIC CIVIL ENGINEERING CIVIL ENGG I/II SEM
BY
Prateek Sharma
Asst. Professor in Civil Engineering
Deptt.
G.I.T JAIPUR
Unit – 3
Surveying

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UNIT 3
BASIC CIVIL ENGINEERING
JAIPUR

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RTU SYLLABUS:
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Surveying: Object & principles of Surveying, plans and maps, Scales, Unit of
measurement. Linear measurements: Direct measurements- Tape & Chain,
Ranging out survey lines, taking measurements of sloping ground. Tape
correction, conventional symbols.
Introduction to Compass Surveying & Leveling.
Introduction to total station,
Contour maps

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BLOWN UP:
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3.1 Surveying: Object
3.1.1 Principles of Surveying
3.2 Plans
3.2.1 Maps
3.3 Unit of measurement
3.3.1 Scales
3.4 Linear measurements: Direct measurements.
3.5 Tape
3.6 Chain
3.7 Ranging out survey lines
3.8 Measurements on sloping ground
3.9 Tape correction
3.10 Conventional symbols
3.11 Introduction to Compass Surveying
3.12 Introduction to Leveling
3.13 Introduction to total station
3.14 Contour maps

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3.1 Objectives,
• The primary object of survey is the preparation of plan estate or buildings roads, railways,
pipelines, canals, etc. Or to measure area of field, state, nation.
• Object of geodetic surveying is to determine precise positions on the surface of the earth
of widely distant points.
Some of Objectives are as below:
1 To determine the relative position of any objects or points of the earth.
2 To determine the distance and angle between different objects.
3 To prepare a map or plan to represent an area on a horizontal plan.
4 To develop methods through the knowledge of modern science and the technology and
use them in the field.

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1. Principle of working from whole to part –
• It is a fundamental rule to always work from the whole to the part. This implies a precise
control surveying as the first consideration followed by subsidiary detail surveying.
• This surveying principle involves laying down an overall system of stations whose
positions are fixed to a fairly high degree of accuracy as control, and then the survey of
details between the control points may be added on the frame by less elaborate methods.
• Once the overall size has been determined, the smaller areas can be surveyed in the
knowledge that they must (and will if care is taken) put into the confines of the main
overall frame.
• Errors which may inevitably arise are then contained within the framework of the control
points and can be adjusted to it.
• Surveying is based on simple fundamental principles which should be taken into
consideration to enable one get good results.

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1. Principle of working from whole to part –
• It is achieved by covering the area to be surveyed with a number of spaced out control
point called primary control points called primary control points whose pointing have been
determined with a high level of precision using sophisticated equipments.
• Based on these points as theoretic, a number of large triangles are drawn. Secondary
control points are then established to fill the gaps with lesser precision than the primary
control points.
• At a more detailed and less precise level, tertiary control points at closer intervals are
finally established to fill in the smaller gaps.
• The main purpose of surveying from the whole to the part is to localize the errors as
working the other way round would magnify the errors and introduce distortions in the
survey.
• In partial terms, this principle involves covering the area to be surveyed with large
triangles.
• These are further divided into smaller triangles and the process continues until the area has
been sufficiently covered with small triangles to a level that allows detailed surveys to be
made in a local level.
• Error is in the whole operation as the vertices of the large triangles are fixed using higher
precision instruments.

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2. ) Using measurements from two control parts to fix other points –
• Given two points whose length and bearings have been accurately determined, a line can
be drawn to join them hence surveying has control reference points. The locations of
various other points and the lines joining them can be fixed by measurements made from
these two points and the lines joining them. For an example, if A and B are the control
points, the following operations can be performed to fix other points.
i) Using points A and B as the centers ascribe arcs and fix (where they intersect).
ii) Draw a perpendicular from D along AB to a point C.
iii) To locate C, measure distance AB and use your protractor to equally measure angle ABC.
iv) To locate C the interior angles of triangle ABC can be measured. The lengths of the sides
AC and BC can be calculated by solving the triangle.

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3.2 Plans
Planning maps:
A map is a visual representation of an area a symbolic depiction highlighting relationships
between elements of that space such as objects, regions, and themes.
Plans are a set of two-dimensional diagrams or drawings used to describe a place or an
object, or to communicate building or fabrication instructions.

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3.2.1 Maps

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3.3 Unit of measurement

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Scales in Civil Engineering:
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Types of Scales: Types of Scales in engineering drawing, Plain Scale, Diagonal Scales,
Comparative Scale, Fernier Scale, Scale of Chords Scales are classified as:
1. Plain Scale
2. Diagonal Scales
3. Scale of Chords
Plain Scale Plain scale is cleanly a line which is separated into a proper number of equal
parts, first of which is further sub-divided into small parts. It is use to represent either two
units or a unit or a unit and its fraction for example km and hm, m and dm, cm and mm etc.
3.3.1 Scales

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Plain Scale:
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Plain Scale: Plain scale is cleanly a line which is separated into a proper number of equal
parts, first of which is further sub-divided into small parts. It is use to represent either two
units or a unit or a unit and its fraction for example km and hm, m and dm, cm and mm etc.
1. Plain Scale

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Diagonal Scales :
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2. Diagonal Scales: Diagonal scale is use to signify three units. i.e., main unit, its sub-unit
and further sub-division of subunit. Such as, a diagonal scale can signify (a) metres,
decimetres and centimetres (b) kilometre, hectometre and decameter (c) yards, feet and
inches and so on. Sub-division of small unit of a plain scale is prepared by diagonal principal.
As third unit of scale is calculated by the help of this diagonal the scale is being name as
diagonal scale.

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Scale of Chords:
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5. Scale of Chords: In absence of a protractor, a scale of chords can be use to calculate angle
or to set necessary angle.
Process: Draw a line AB and divide in Nine equal parts . Draw an arch having A as center
and AB as radius. Now draw the arch CB. Taking O as center Draw another arch AC. Now
connect C to O point. Now complete all arch’s on line AB extending to Arch AC. Connect
all intersection points to O. Your Scale of Chords is ready. You can measure any angle on it.

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3.4 Linear measurements: Direct measurements.
The three different methods to measure linear distances is the Direct measurement method,
measurement by Optical means and Electro-magnetic methods. The merit of each method is
dependent on the accuracy of the values provided by each method.

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3.5 Tape

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3.5 Tape –
• Tapes are used where greater accuracy of measurements are required, such as the setting
out of buildings and roads. They are 15m or 30m long marked in metres, centimeter and
millimeters. Tapes are classified into four types;
•i. Linen or cloth tape - Linen tape, also known as cloth tape is a varnished strip made of
closely woven linen. The width of the strip is about 12 to 16 mm. It is available in different
lengths such as 10m, 20m, 30m, and 50m. Both ends of the linen tape are provided with
metallic handles and the whole tape is wounded in leather or metal case.
•Linen tapes are light in weight and easy to handle. These tapes may shrink when exposed to
water and also elongate when pulled. Hence, these tapes are not suitable for accurate
surveying measurements. These are generally used for measuring offsets and for ordinary
works.
ii Metallic tape -A steel tape consists of a light strip of width 6 to 10 mm and is more
accurately graduated as compared to cloth and metal tape. Steel tapes are available in lengths
of 1, 2, 10, 20, 30 and 50 metres. The tapes of lengths 10, 20, 30 & 50 metres are provided
with a brass ring at outer end, fastened to it by a metal strip of the same width of the tape.

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3.5 Tape -
iii. Steel Tape - A steel tape consists of a light strip of width 6 to 10 mm and is more accurately
graduated as compared to cloth and metal tape. Steel tapes are available in lengths of 1, 2, 10, 20,
30 and 50 metres.
• The tapes of lengths 10, 20, 30 & 50 metres are provided with a brass ring at outer end, fastened
to it by a metal strip of the same width of the tape.
• The length of the tape is included in metal ring. Steel tapes vary in quality and in accuracy of
graduation, but even a poor steel tape is generally more useful and accurate as compared to
cloth or metallic tape.
• Steel tapes are wound on a corrosion resisting metal case with winding device.
• Steel tape is a delicate and light weight instrument hence it cannot withstand rough usage. Tape
should be cleaned, dried and oiled after use so that it does not get rusted.
iv. Invar tape - Invar tapes are available in lengths of 20, 30 and 100 metres. Invar tapes are
used whey high degree of accuracy and precision in linear measurements is required such as
measurement of base lines. Invar tapes are made of alloys of nickel and steel and have very
low coefficient of thermal expansion. Invar tapes are more expensive as compared to other
tapes. Main disadvantage of this tape is that it’s length and coefficient of thermal expansion is
not constant. It keeps changing with time. Therefore it is suggested to determine the length
and coefficient of thermal expansion time to time.

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3.6 Chain
• The chain is usually made of steel wire, and
consists of long links joined by shorter
links. It is designed for hard usage, and is
sufficiently accurate for measuring the
chain lines and offsets of small surveys.

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3.6 Chain
• Chains are made up of links which measure 200mm from centre to centre of each
middle connecting ring and surveying brass handless are fitted at each end.
• Tally markers made of plastic or brass are attached at every whole metre position or
at each tenth link. To avoid confusion in reading, chains are marked similarly form
both end (E.g. Tally for 2m and 18m is the same) so that measurements may be commenced
with either end of the chain.
•There are three different types of chains used in taking measurement namely:

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3.6 Chain : -
A. Metric chains
Metric chains are the most commonly used chain in India. These types of chains comes in
many lengths such as 5, 10, 20 and 30 meters. Most commonly used is 20m chain. Tallies are
provided at every 2m of the chain for quick reading. Every link of this type of chain is 0.2m.
The total length of the chain is marked on the brass handle at the ends.
B. Gunter’s chain or surveyor’s chain
Gunter chain comes in standard 66ft. These chain consists of 100links, each link being 0.66ft
or 7.92inches. The length 66ft is selected because it is convenient in land measurements.
C. Engineer’s chain
This chain comes in 100ft length. Its consist of 100 links each link being 1ft long. At every 10
links a brass ring or tags are provided for indication of 10 links. Readings are taken in feet and
decimal.
D. Revenue Chain
The standard size of this type of chain is 33ft. The number of links are 16, each link being 2
ft. This chain is commonly used in cadastral survey

Arrows:
Arrow consists of a piece of steel wire about 0.5m long, and is used for marking
temporary stations. A piece of colored cloth, white or red ribbon is usually attached
or tied to the end of the arrow to be clearly seen on the field.
R.T.U KOTA / G.I.T JAIPUR JAIPUR SURVEYING CIVIL ENGG / III SEM
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Pegs
•Pegs are made of wood 50mm x 50mm and some convenient
length. They are used for points which are required to be
permanently marked, such as intersection points of survey lines.
Pegs are driven with a mallet and nails are set in the tops.

 Ranging Rod:
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These are poles of circular section 2m, 2.5m or 3m long, painted with characteristic
red and white bands which are usually 0.5m long and tipped with a pointed steel shoe
to enable them to be driven into the ground. They are used in the measurement of lines
with the tape, and for marking any points which need to be seen.

 This instrument is used for setting out lines at right angle to main chain line. It is
used where greater accuracy is required. There are two types of optical square, one
using two mirrors and the other a prism.
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• The mirror method is constructed based on the fact that a ray of light is reflected
from a mirror at the same angle as that at which it strikes the mirror.
• The prism square method is a simplified form of optical square consisting of a
single prism. It is used in the same way as the mirror square, but is rather more
accurate.

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This consists of two pairs of vanes set at right angle to each other with a wide and
narrow slit in each vane.
The instrument is mounted upon a pole, so that when it is set up it is at normal eye
level. It is also used for setting out lines at right angle to the main chain line.

 NECESSARY PRECAUTIONS IN USING CHAIN SURVEYING
INSTRUMENTS
1. After use in wet weather, chains should be cleaned, and steel tapes should
be dried and wiped with an oily rag.
2. A piece of colored cloth should be tied to arrow (or ribbon – attached)
to enable them to be seen clearly on the field.
3. Ranging rods should be erected as vertical as possible at the exact station point.
4. The operating tension and temperature for which steel bands/tapes
are graduated should be indicated.
5. Linen tapes should be frequently tested for length (standardized) and
always after repairs.
6. Always keep tapes reeled up when not in use.
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 GENERAL PROCEDURE IN MAKING A CHAIN SURVEY
1. Reconnaissance: Walk over the area to be surveyed and note the general layout,
the position of features and the shape of the area.
2. Choice of Stations: Decide upon the framework to be used and drive in the station
pegs to mark the stations selected.
3. Station Marking: Station marks, where possible should be tied - in to a
permanent objects so that they may be easily replaced if moved or easily
found during the survey. In soft ground wooden pegs may be used while
rails may be used on roads or hard surfaces.
4.Witnessing: This consists of making a sketch of the immediate area around
the station showing existing permanent features, the position of the stations and
its description and designation. Measurements are then made from at least
three surrounding features to the station point and recorded on the sketch.
 The aim of witnessing is to re-locate a station again at much later date even by
others after a long interval.
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 GENERAL PROCEDURE IN MAKING A CHAIN SURVEY
 5. Offsetting:-Offsets are usually taken perpendicular to chain lines in order to
dodge obstacles on the chain line.
 6. Sketching the layout on the last page of the chain book, together with the date
and the name of the surveyor, the longest line of the survey is usually taken as the
base line and is measured first.
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CRITERIA FOR SELECTING A SURVEY LINES/OFFSETS
During reconnaissance, the following points must be borne in mind as the criteria to
provide the best arrangement of survey lines.
a. Survey lines: the number of survey lines should be kept to a minimum but must be
sufficient for the survey to be plotted and checked.
b. Long base line: A long line should be positioned right across the site to form a base
on which to build the triangles.
c. Well conditioned triangle with angles greater than 30 degree and not exceeding 150
:
It is preferable that the arcs used for plotting should intersect as close as 900
in order to
provide sharp definition of the stations point.
d. Check lines: Every part of the survey should be provided with check lines that are
positioned in such a way that they can be used for offsetting too, in order to save any
unnecessary duplication of line.
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CRITERIA FOR SELECTING A SURVEY LINES/OFFSETS
e. Obstacles such as steep slopes and rough ground should be avoided as far as possible.
f. Short offsets to survey lines (close feature preferably 2m) should be selected: So
that measuring operated by one person can be used instead of tape which needs
two people.
g. Stations should be positioned on the extension of a check line or triangle. Such
points can be plotted without the need for intersecting arcs.
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3.7 Ranging Out Survey Lines

 Ranging involves placing ranging poles along the route to be measures so as to get
a straight line. The poles are used to mark the stations and in between the stations.
(a) Direct Ranging
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 Ranging involves placing ranging poles along the route to be measures so as to get
a straight line. The poles are used to mark the stations and in between the stations.
(b) Indirect Ranging – When two points are not visible due to the hill or high
ground between them.
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3.8 Measurements on sloping ground

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3.9 Tape Correction
• The following corrections are to be applied to the linear measurements with a
chain or a tape where such accuracy is required.
(i) Correction for absolute length
(ii) Correction for pull or tension
(iii) Correction for temperature
(iv) Correction for Sag
(v) Correction for Slope
(vi) Correction for Alignment
(vii) Reduction for the sea level

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3.9 Tape Correction
1. Correction for Absolute Length
• If Ca is the correction for absolute length or the actual length, then it is given by:
• Ca = L.c/l
• Where, L = Measured length of the line; c = Correction per tape length; l= designated
length of the tape or the nominal length.
• Different cases are:
• Absolute length > Designated length means Measured distance is short, hence the
correction is additive.
• Absolute length < Designated length means, Measured distance is long, hence the
correction is subtractive.
• The sign of correction Ca is the same as that of ‘c’.

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3.9 Tape Correction
(ii) The correction for temperature Ct is given by
the formula:

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3.9 Tape Correction
(iii) Correction for pull or tension

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3.9 Tape Correction
(iv) . Correction for Sag
• Stretching the tape between two supports make the tape to form a horizontal
catenary. Hence, the horizontal distance becomes greater than the distance along the
curve. Hence,
• Sag Correction = Horizontal distance – length along the horizontal catenary
• As shown in the figure below, the curve is assumed as a parabola to facilitate the
calculation of correction for sag.
•
Tape correction per length is given by,
Cs = lW2 /24n2P2
Where, Cs = Tape Correction per Tape length; l=Total length of the tape; W= total
weight of the tape; n= number of equal spans; P= Pull applied;

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3.9 Tape Correction
•
(v) Correction for Slope or Vertical Alignment

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3.10 Conventional symbols

 Meaning and types of compass survey
 In compass survey, the direction of the survey line is measured by the use of a
magnetic compass while the lengths are by chaining or taping. Where the area to be
surveyed is comparatively large, the compass survey is preferred, whereas if the area
is small in extent and a high degree of accuracy is desired, then chain survey is
adopted. However, where the compass survey is used, care must be taken to make
sure that magnetic disturbances are not present. The two major primary types of
survey compass are: the prismatic compass and surveyors compass.
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Compass surveys are mainly used for the rapid filling of the detail in larger surveys
and for explanatory works.

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This is an instrument used for the measurement of magnetic bearings. It is small and
portable usually carried on the hand.
This Prismatic Compass is one of the two main kinds of magnetic compasses included
in the collection for the purpose of measuring magnetic bearings, with the other being
the Surveyor's Compass.
The main difference between the two instruments is that the surveyor's compass is
usually larger and more accurate instrument, and is generally used on a stand or tripod.

 The prismatic compass on the other hand is often a small instrument which is held
in the hand for observing, and is therefore employed on the rougher classes of
work.
 The graduations on this prismatic compass are situated on a light aluminum ring
fastened to the needle, and the zero of the graduations coincides with the south
point of the needle.
 The graduations therefore remain stationary with the needle, and the index turns
with the sighting vanes.
 Since the circle is read at the observer's (rather than the target's) end, the
graduations run clockwise from the south end of the needle (0º to 360º), whereas in
the surveyor's compass, the graduations run anti-clockwise from north.
 The prismatic attachment consists of a 45º reflecting prism with the eye and
reading faces made slightly convex so as to magnify the image of the graduations.
The prism is carried on a mounting which can be moved up and down between
slides fixed on the outside of the case.
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 The purpose of this up-and-down movement is to provide an adjustment for
focusing.
 The image of the graduations is seen through a small circular aperture in the prism
mounting, and immediately above this aperture is a small V cut on top of the
mounting, over which the vertical wire in the front vane may be viewed.
 Using the V cut, the vertical wire and the station whose bearing is required are
viewed in one line, the bearing is directly read off the graduated arc at the point
immediately underneath the vertical wire.
 The mirror located in front of the forward vane slides up and down the vane, and is
hinged to fold flat over it or to rest inclined at any angle with it.
 This mirror is used for solar observations, or for viewing any very high object, and
is not a normal fitting to a compass.
 The two circular discs in front of the back vane are dark glasses which can be
swung in front of the vane when solar observations are being taken.
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 Prismatic compass consists of a non-magnetic metal case with a glass top and contain the following:
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 Elements of prismatic compass
 Cylindrical metal box:
Cylindrical metal box is having diameter of 8to 12 cm. It protects the compass and
forms entire casing or body of the compass. It protect compass from dust, rain etc.
 Pivot:
Pivot is provided at the center of the compass and supports freely suspended
magnetic needle over it.
Lifting pin and lifting lever:
 lifting pin is provided just below the sight vane. When the sight vane is folded, it
presses the lifting pin. The lifting pin with the help of lifting lever then lifts the
magnetic needle out of pivot point to prevent damage to the pivoted.
 Magnetic needle:
Magnetic needle is the heart of the instrument. This needle measures angle of a line
from magnetic meridian as the needle always remains pointed towards north South
Pole at two ends of the needle when freely suspended on any support.
 Graduated circle or ring:
This is an aluminum graduated ring marked with 0o to 360o to measures all possible
bearings of lines, and attached with the magnetic needle. The ring is graduated to half
degree.
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 Elements of prismatic compass
 Prism :
prism is used to read graduations on ring and to take exact reading by compass. It is
placed exactly opposite to object vane. The prism hole is protected by prism cap to
protect it from dust and moisture.
 Object vane:
Object vane is diametrically opposite to the prism and eye vane. The object vane is
carrying a horse hair or black thin wire to sight object in line with eyesight.
 Eye vane:
Eye vane is a fine slit provided with the eye hole at bottom to bisect the object from
slit.
 Glass cover:
 It covers the instrument box from the top such that needle and graduated ring is seen
from the top.
 Sun glasses:
These are used when some luminous objects are to be bisected.
 Reflecting mirror:
It is used to get image of an object located above or below the instrument level
while bisection. It is placed on the object vane.
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 The following procedure should be adopted after fixing the prismatic compass on
the tripod for measuring the bearing of a line.
 Centering :
Centering is the operation in which compass is kept exactly over the station from
where the bearing is to be determined. The centering is checked by dropping a
small pebble from the underside of the compass. If the pebble falls on the top of the
peg then the centering is correct, if not then the centering is corrected by adjusting
the legs of the tripod.
 Leveling :
Leveling of the compass is done with the aim to freely swing the graduated
circular ring of the prismatic compass. The ball and socket arrangement on the
tripod will help to achieve a proper level of the compass.
 Focusing:
The prism is moved up or down in its slide till the graduations on the aluminum
ring are seen clear, sharp and perfect focus. The position of the prism will depend
upon the vision of the observer.
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 OPERATION PROCEDURE
 Remove the corner and open out the prism and window, holding the compass as
level as possible.
 Then focus the prism by raising or lowering its case until the divisions appear sharp
and clear. If necessary with the needle on to its pivot.
 Holding the compass box with the thumb under the prism and the forefinger near
the stud, sight through the objector station lowering the eye to read the required
bearing as soon as the needle comes to rest naturally.
 The bearing read will be a forward bearing and normally a “whole circle” bearing
clockwise angle between 0 degree to 360 degree.
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 Surveyor’s Compass:
 Similar to the prismatic compass but with few modifications, the surveyors
compass is an old form of compass used by surveyors. It is used to determine the
magnetic bearing of a given line and is usually used in connection with the chain or
compass survey.
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The important parts and the construction of surveyor compass are similar to that of a
prismatic compass except for the following points.
(1) Whereas the prismatic compass consists of a reflecting prism along with the eye
vane, the surveyor’s compass consists of only a narrow vertical slit instead of a prism.
(2) The magnetic needle is of broad form in a prismatic compass whereas it is of an
edge-bar type in a surveyor compass.
(3) In the surveyor compass the graduated circle is fixed to the box and moves with the
box while the magnetic needle remains stationary along the north-south line.
(4) In a prismatic compass, as the reflecting prism carries the eye vane also, the sighting
of the object and taking the reading are done simultaneously, whereas in a surveyor
compass the object should be sighted first and then the surveyor should go round the
instrument to read the graduation on the graduated ring corresponding to the north end of
the needle. The readings are taken with the naked eye.
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(5) In a Surveyor Compass, the ring is divided into four quadrants and graduations are
made from 0 to 90 degrees in each quadrant.0 degrees is marked at the North and South
points, and 90 degrees is marked at the east and west points. The letter E and W are
interchanged from their true position so that the bearing of a line may be read in the
correct quadrant.
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(6) Whereas the prismatic compass may be held in hand for taking the reading,
the surveyor’s compass should be supported on a tripod.

Bearing of line : Direction with respect to a given meridian.
Meridian is a fixed reference line.
 Types of meridian and bearing
 True Meridian - Line through true north and south poles, and this remains constant
throughout. To find out this line, we need astronomical observations.
 Bearing with respect to true meridian is known as true bearing.
 Magnetic Meridian - Direction indicated by freely suspended magnetic needle, and this
magnetic N-S line changes with location and time as they are affected by earth’s
magnetism.
 Bearing with respect to magnetic meridian is known as magnetic bearing.
 Arbitrary Meridian - Well defined reference object like a tower whose position is not
going to change, directions are measured with respect to it and they are known as
arbitrary bearings.
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 Introduction:
 In this section, we will examine the back and fore bearing; and the steps to be taken
when traversing with compass survey.
 Back and fore bearing
 Fore bearing is the compass bearing of a place taken from a status to the other in
the direction that the survey is being carried out.
 The back bearing in the other hand is the bearing in the opposite direction i.e. the
bearing taken backwards from the next station to its preceding station that the fore
bearing was taken.
 The difference between BB and FB is always 180.
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 The bearing are designated in the following two system:-
 1) Whole Circle Bearing System.(W.C.B)
 2) Quadrant Bearing System.(Q.B)
 Whole circle bearing system(W.C.B.)
 The bearing of a line measured with respect to magnetic meridian in clockwise
direction is called magnetic bearing and its value varies between 0ᴼ to360ᴼ.
 A bearing that defines the direction of a survey line by its horizontal angle
measured clockwise from true north.
 Quadrantal bearing system (Q.B.)
 In this system, the bearing of survey lines are measured with respect to north line or
south line whichever is the nearest to the given survey line and either in clockwise
direction or in anti clockwise direction.
 Reduced bearing (R.B)
 When the whole circle bearing is converted into Quadrantal bearing, it is termed as
“REDUCEDBEARING”.
 Thus , the reduced bearing is similar to the Quadrantal bearing.
 Its values lies between 0ᴼ to 90ᴼ, but the quadrant should be mentioned for proper
designation.
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 Traversing with the compass involves taking the bearing along a series of
connecting straight lines and in the same time measuring the distances with the
tape. The compass is read at each point and a back bearing is equally taken to serve
as a check. This continues until the traverse closes.
 Choosing a suitable scale, the traverse is then plotted taking into consideration the
general shape of the area.
 Observing Bearing of Line
 Consider a line AB of which the magnetic bearing is to be taken.
 By fixing the ranging rod at station B we get the magnetic bearing of needle with
respect to North Pole.
 The enlarged portion gives actual pattern of graduations marked on ring.
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 Local attraction is the influence that prevents magnetic needle pointing to
magnetic north pole.
 Unavoidable substance that affect are:
 Magnetic ore.
 Underground iron pipes.
 High voltage transmission line.
 Electric pole etc.
 Influence caused by avoidable magnetic substance doesn‟t come under local
attraction such as instrument, watch wrist, key etc.
 Detection of Local attraction
 By observing the both bearings of line (F.B. & B.B.) and noting the difference (180
degree in case of W.C.B. & equal magnitude in case of R.B. We confirm the local
attraction only if the difference is not due to observational errors.
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 Checks in closed Traverse
 Errors in traverse is contributed by both angle and distance measurement
 Checks are available for angle measurement but
 There is no check for distance measurement
 For precise survey, distance is measured twice, reverse direction second time.
 Checks for angular error are available
 Interior angle, sum of interior angles = (2n-4) x right angle, where n is number of
traverse side
 Exterior angle, sum of exterior angles = (2n+4) x right angle, where n is number of
traverse side
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Prismatic Compass

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3.11 Comparison between Prismatic & Surveyor’s Compass
SR.N
O.
ITEM. SURVEYOR COMPASS. PRISMATIC SURVEY
1 Magnetic
Needle
The needle is of edge bar type The needle is a broad needle.
2 Graduated
Ring
1. The graduated ring is attached to the box and
rotates along with the line of sight.
2. The graduations have 0° at N and S., and 90° at E
and W. The letters E and W are interchanged from
their true positions to read the bearing in its proper
quadrant (below fig.). As the graduated ring is
attached to the box, it moves with the sight. If the
hearing of a line in the first quadrant is to be
measured, since the letters E and W are reversed
from their natural positions, the proper quadrant NE
will be read
3. The graduations are engraved erect, since the
graduated ring is read directly.
1. The graduated ring is attached with the needle and does not
rotate with the line of sight.
2. The graduations have 0° at S, 90° at W, 180° at N and 270° at E
(as below fig.). When the needle points north, the reading under
the prism should be zero. It is so because the prism is placed
exactly opposite the object vane, i.e. on the observer's side, and
the south end will be under the prism while the needle points
north. Hence, the Zero is placed at the south end then the ring is
graduated clockwise from it
3. Graduations are engraved inverted since the graduated ring is
read through the prism.
3 Reading
System
1. The readings are taken directly by seeing through
the top of the box glass.
2. Sighting and reading cannot be done
simultaneously.
1. The readings are taken with the help of a prism, provided at the
eye vane.
2. Sighting and reading can be done simultaneously.
4 Tripod The instrument cannot be used without a tripod. The instrument can be held in hand also while making the
observations.
5 Vanes The eye vane consists of the small vane with a small
slit.
The eye vane consists of a metal vane with a large slit.

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3.12 Introduction to Leveling

 Levelling or leveling is a branch of surveying, the object of which is to establish or
verify or measure the height of specified points relative to a datum.
 It is widely used in cartography to measure geodetic height, and in construction
to measure height differences of construction artifacts.
 Leveling is the general term applied to any of the various processes by which
elevations of points or differences in elevation are determined.
R.T.U / G.I.T Jaipur Surveying (3CE4-05) CIVIL ENGG./ III SEM
PRATEEK SHARMA
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Basic terms:
 Vertical line- A line that follows the local direction of gravity as indicated by
a plumb line.
 Level surface - A curved surface that, at every point is perpendicular tothe local
plumb line (the direction in which gravityacts).
 Level line - A line lying in a level surface is a level line. It is thus a curved line normal
to the plumb at all points. In field surveying, it is defined by the direction of a freely
suspended plumb-bob.
 Horizontal plane - A plane perpendicular to the local direction of gravity.In plane
surveying, it is a plane perpendicular to the local verticalline.
 Horizontal line - A line in a horizontal plane. In plane surveying, it is aline
 perpendicular to the local vertical.
 Vertical datum - Any level surface to which elevations are referenced. This is the
surface that is arbitrarily assigned an elevation of zero.
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 Elevation - The distance measured along a vertical line from a verticaldatum
to a point or object.
 Benchmark (BM) - A relatively permanent object, natural or artificial, having a
marked point whose elevation above or below a reference datum is known or assumed.
• Station- A point where the leveling staff is kept.

 Height of instrument: It is the elevation of the plane of sight with respect to
assumed datum. It is also known as plane of collimation.
 Back sight(BS): It is the sight taken on the level staff, of a known elevation with the
intention to obtain the elevation of plane of collimation. It is called PLUS sight
because it is added to elevation of that point to get height of instrument or plane of
collimation.
 Intermediate sights(IS): These are the sight taken after back sightand before sighting
the final point. These are called MINUS sights. These are subtracted from plane of
collimation to find the reduced level of different points.
 Fore sight(FS): The last reading taken from the instrument. This isalso a MINUS sight.
 Change point(CP) or turning point(TP): The point at which both BSand FS are taken.
 Reduced level(RL): The elevations of the points with respect to assumed
datum.
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Levelling Terms

 Simple levelling
 Differential levelling
 Fly levelling
 Profile levelling
 Cross sectional levelling
 Reciprocal levelling
 There are two methods for obtaining the elevations at different points:
- Height of instrument (or plane of collimation) method
- Rise and fall method
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 When the difference in the elevation of two nearby pointsis required then simple
levelling is performed.
 Assume the elevation of BM Rock is known to be 820.00 ft.
 The BS at BM Rock is 8.42ft. So HI = (820 + 8.42)ft.
 Now the FS on “X” is 1.2ft.
 So the RL at “X” = HI – FS= 828.42ft
 Note that the RL of theinstrument station will never comes in the calculation.

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 Performed when the final point is very far from the final point.
 We have to find RL at B.
 It is given that RL at A is 100m and BS at A is 2.45m
 So, HI at L1=(100+2.45)=102.45m
 FS at CP1=2.41m
 RL at CP1=(102.45-2.14)=100.31m
 Now BS at CP1=1.43m
 HI at L2=(100.31+1.43)=101.74m
 FS at CP2=2.18m
 RL at CP2=(101.74-2.18)=99.56m
 BS at CP2=1.38m
 HI at L3=(99.56+1.38)m=100.94m
 FS at B=1.54m
 RL at B= (100.94-1.54)=99.4m (ans)

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 Performed when the work site is very far away from the bench mark.
 The surveyor starts by taking BS at BM and proceed towards worksite till he finds a
suitable place for temporary BM.
 All works are done with respect to temporary BM.
 At the end of the day the surveyor comes back to original BM.
 This is called fly levelling.
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 Profile leveling, which yields elevations at definite points along a reference line,
provides the needed data for designing facilities such as highways, railroads,
transmission lines.
 Reduced levels at various points at regular interval along the line is calculated.
 After getting the RL of various points the profile is drawn. Normally vertical scale is
much larger than horizontal scale for the clear view of the profile.
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Plan
Sectional
View

 In many projects not only profile along the line is required but also profile of
Cross- section at a regular interval is required. (here 20m)
 Levels are taken at every 3m distance (till 9m i.e. 3 readings on one side) to left and
right of the line AB and BC for cross section profile.
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 We have found by the principle of equalizing backsight and foresight distances that if
the level is placed exactly midway between two points and staff reading are taken to
determine the difference of level, then the errors (due to inclined of collimation line,
curvature and refraction) are automatically eliminated.
 But in the case of a river or valley, it is not possible to set up the level midway between
the two points on opposite banks. In such case the method of reciprocal levelling is
adopted, which involves reciprocal observation both banks of the river or valley.
 In reciprocal leveling, the level is set up on the both banks of the river or valley and
two sets of staff readings are taken by holding the staff on both banks.
 In this case, it is found that the errors are completely eliminated and true difference of
level is equal to the mean of the true apparent differences of level.
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(A) Height of Instrument Method :-
The basic equations are :-
 Height of instrument for the first setting= RL of BM + BS(at BM)
 Subtract the IS and FS from HI to get RL of intermediate stations and change points.
 Checking: ∑BS - ∑FS = Last RL – First RL. This is –ve for FALL and +ve for RISE.
(B) Rise and Fall method :-
 In this method the difference of the present staff reading is subtracted from the
previous staff reading.
 Previous reading – present staff reading = +ve, denotes RISE
 Previous reading – present staff reading = -ve, denotes FALL
 Checking: ∑BS - ∑FS = Last RL – First RL= ∑Rise - ∑Fall
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 Cc is always negative.
 A properly adjusted instrument take the readings with respect to horizontal line.
 So something has to be subtracted from the staff reading to get actual reading.
 Cc= d2/2R and -ve
 D is distance of the staff from the point of tangency and R is the radius of the Earth =
6370km
 Cc= -7.849 x 10-8 x d2 meters, if d is inmeters.
 Effect of refraction (Cr)
 Air is denser near the earth and becomes thinner as we go far from the surface of the
earth. This causes refraction.
 Cr=(1/7) x (d2/2R) and +ve
 Combined effect
 Cc + Cr = - (6/7) x (d2/2R) = - 6.728 x 10-8 x d2 meters,if d is in meters.

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 A Level is an instrument with a telescope that can be leveled with a spirit bubble.
 A level is basically a telescope attached to an accurate levelling device, set upon a
tripod so that it can rotate horizontally through 360°.
 The optical line of sight forms a horizontal plane, which is at the same elevation
as the telescope crosshair.
 By reading a graduated rod held vertically on a point of known elevation (Bench
Mark) a difference in elevation can be measured and a height of instrument (H.I.)
calculated by adding the rod reading to the elevation of the bench mark.
 Once the height of instrument is established, rod readings can be taken on
subsequent points and their elevations calculated by simply subtracting the
readings from the height of instrument.

Devices are classified leveling in terms of accuracy into three categories:
1. Precision: the settlement where the bubble is very sensitive as are high magnification
power and uses this type of work and Geodetic Survey businesses that require high
precision.
2. Precision medium: It is less accurate than the first category and dominated the use of
this type in most engineering projects.
3. Low-precision devices: and make this kind of hardware specifically for the purposes of
settlement approximate as in building projects Ltd. and settlement cases within short
distance.
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(a) Dumpy levels - These are more basic levels often used in construction work. The
telescope is rigidly attached to a single bubble and the assembly is adjusted either by
means of a screwed ball-joint or by foot screws which are adjusted first in one
direction, then at 90°.
(b) Tilting levels -This type of level is fitted with a circular bubble for preliminary
approximate levelling and a main bubble which is attached to the telescope.
 For each observation (not setup) the main bubble is viewed through an eyepiece and
the telescope tilted by a fine screw to bring the two ends of the bubble into
coincidence.
(c) Automatic levels - This more modern type of level is now in general use. It has a
compensator which consists of an arrangement of three prisms. The two outer ones are
attached to the barrel of the telescope.
 The middle prism is suspended by fine wiring and reacts to gravity. The instrument is
first levelled approximately with a circular bubble; the compensator will then deviate
the line of sight by the amount that the telescope is out of level.
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(b) Tilting levels –
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(c) Auto levels –
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Leveling of the instrument is done to make the vertical axis of the instrument truly vertical.
It is achieved by carrying out the following steps:
Step 1: The level tube is brought parallel to any two of the foot screws, by rotating the
upper part of the instrument. Step 2: The bubble is brought to the centre of the level tube
by rotating both the foot screws either inward or outward. (The bubble moves in the same
direction as the left thumb.)
Step 3: The level tube is then brought over the third foot screw again by rotating the upper
part of the instrument. Step 4: The bubble is then again brought to the centre of the level
tube by rotating the third foot screw either inward or outward.
Step 4: The bubble is then again brought to the centre of the level tube by rotating the third
foot screw either inward or outward.
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There are following types of Errors in Leveling :-
1.Instrumental Errors
2.Collimation Error
3.Error due to Curvature & Refraction
4.Other Errors
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1. Instrumental error and Correction
a) Collimation error
Correction: Check before use and equalise sights.
b)Under sensitive bubble.
c)Errors in staff graduation
Correction: Check
d)Loose tripod head.
e)Telescope not parallel to bubble tube
Correction: Permanent adjustment.
f) Telescope not at right angles to the vertical axis
Correction: Permanent adjustment
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2. Error of Collimation
Collimation error occurs when the collimation axis is not truly horizontal when the
instrument is level. The effect is illustrated in the sketch below, where the collimation axis
is tilted with respect to the horizontal by an angle a.
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3. Curvature & Refraction
The earth appears to “fall away” with distance. The curved shape of the earth means that
the level surface through the telescope will depart from the horizontal plane through the
telescope as the line of sight proceeds to the horizon.
This effect makes actual level rod readings too large by:
Curvature Formula
where D is the sight distance in thousands of feet.
Effects of Curvature are:
 Rod reading is too high
 Error increases exponentially with distance
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4. Other sources of errors in levelling
1. Incorrect setting-up of instrument
2. Movement of staff from position when changing level station
3. Staff not held vertically
4. Parallax: Instrument knocked or moved during backsight-foresight reading
5. Tripod or rod settles between measurements e.g Bubble off center
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3.12 Methods of Leveling
Height of the Instrument Method
The following readings were observed with a levelling instrument, the instrument was
shifted after 5th and 11th reading.
0.585, 1.010, 1.735, 3.295, 3.775(5th)
0.350, 1.300, 1.795, 2.575, 3.375
3.895 (11th), 1.735, 0.635, 1.605
Determine the RLs of various points if the reduced level (RL) of a point on which the
first reading was taken is 136.440 gives the height of collimation method and applies
the check.
HI = RL + BS
= 136.440 + 0.585
= 137.025
RL = HI – IS
Check
(Summation of BS)-(Summation of FS) = Last RL – First RL
2.670 – 9.275 = 129.835 – 136.440
-6.605 = -6.605

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Station BS IS FS HI RL Remarks
123
4
5
0.585
0.350
1.0101.7
35
3.295 3.775
137.025
133.600
136.440
136.015
135.290
133.730
133.250
RL of I
point
CPI
678
9
10 1.735
1.3001.7
952.575
3.375 3.895 131.440
132.300
131.805
131.025
130.225
129.705
CP II
1112 0.635 1.605 130.805
129.835
Sum of
BS=2.67
0
Sum of
FS
=9.275

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3.13 Introduction To Total Station
A Total Station is a modern surveying instrument
that integrates an electronic theodolite with an
electronic distance meter. ... Total Stations use
electronic transit theodolites in conjunction with a
distance meter to read any slope distance from the
instrument to any particular spot.

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3.13 Introduction To Total Station
• 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”.

GLOBAL INSTITUTE OF TECHNOLOGY Surveying (3CE4-05) CIVIL ENGG./ III SEM
PRATEEK SHARMA
PARTS OF A TOTAL STATION

PRATEEK SHARMA

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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

PRATEEK SHARMA
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

PRATEEK SHARMA
 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
PRATEEK SHARMA
• TELESCOPE

PRATEEK SHARMA
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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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.

PRATEEK SHARMA
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).

PRATEEK SHARMA
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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3.13 CONTOURING

 Contour An imaginary line on the ground surface joining the points of equal elevation
is known as contour.
• It facilitates depiction of the relief of terrain in a two dimensional plan or map.
• In other words, contour is a line in which the ground surface is intersected by a
level surface obtained by joining points of equal elevation. This line on the
map represents a contour and is called contour line.
• Contouring is the science of representing the vertical dimension of the terrain on
a two dimensional map.
 Contour Map : A map showing contour lines is known as Contour map.
A contour map gives an idea of the altitudes of the surface features as well as
their relative positions in plan serves the purpose of both, a plan and a section.
 Contouring : The process of tracing contour line on the surface of the earth is
called Contouring.
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Contour Line : A Contour line is an imaginary outline of the terrain obtained by joining its
points of equal elevation.
Contour Interval (CI) – It is the vertical distance between any two consecutive contours.
Suppose a map includes contour lines of 100m, 98m ,96 m and so on .The contour interval
here is 2 m.
This interval depends upon
the nature of the ground (i.e. whether flat or sleep).
the scale of the map
the purpose of the survey.
Contour intervals for flat country are generally small, e g. 0.25 m, 0.5 m, 0.75m. etc.
Contour interval for a steep slope in a hilly area is generally greater. e.g. 5m. 10 m, 15 m
etc.
It should be remembered that the contour interval for a particular map is Constant.
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CHARACTERISTICS OF CONTOURS
 All points in a contour line have the same elevation.
 Flat ground is indicated where the contours are widely separated and steep-slope
where they run close together.
 A uniform slope is indicated when the contour lines are uniformly spaced.
 A plane surface when they are straight, parallel and equally spaced.
 A series of closed contour lines on the 80 map represent a hill 75, if the higher values
are inside.
 A series of closed contour lines on the map indicate a depression if the higher values
are outside
PRATEEK SHARMA
34

1. Direct method
2. Indirect method
1. Direct Method of Contouring
It consists in finding vertical and horizontal controls of the points which lie on the selected
contour line.
For vertical control levelling instrument is commonly used. A level is set on a commanding
position in the area after taking fly levels from the nearby bench mark. The plane of
collimation/height of instrument is found and the required staff reading for a contour line is
calculated.
The instrument man asks staff man to move up and down in the area till the required staff
reading is found. A surveyor establishes the horizontal control of that point using his
instruments.
PRATEEK SHARMA
35

PRATEEK SHARMA
36
After that instrument man directs the staff man to another point where the same staff
reading can be found. It is followed by establishing horizontal control.
Thus, several points are established on a contour line on one or two contour lines and
suitably noted down. Plane table survey is ideally suited for this work.
After required points are established from the instrument setting, the instrument is
shifted to another point to cover more area. The level and survey instrument need not
be shifted at the same time. It is better if both are nearby to communicate easily.
For getting speed in levelling some times hand level and Abney levels are also used.
This method is slow, tedious but accurate. It is suitable for small areas.

2. Indirect Method of Contouring –
In this method, levels are taken at some selected points and their levels are reduced. Thus
in this method horizontal control is established first and then the levels of those points
found.
After locating the points on the plan, reduced levels are marked and contour lines are
interpolated between the selected points.
For selecting points any of the following methods can be used:
a. Method of squares
b. Method of cross-section
c. Radial line method
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37
Method of Contouring

a. Method of Squares - In this method area is divided into a number of squares and all
grid points are marked (Fig.).
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38
Commonly used size of square varies from 5 m × 5 m to 20 m × 20 m. Levels of all
grid points are established by levelling. Then grid square is plotted on the drawing
sheet. Reduced levels of grid points marked and contour lines are drawn by
interpolation Fig.

b. Method of cross-section
In this method cross-sectional points are taken at regular interval. By levelling the reduced
level of all those points are established. The points are marked on the drawing sheets, their
reduced levels (RL) are marked and contour lines interpolated.
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39
Figure shows a typical planning of this work. The spacing of cross-section depends
upon the nature of the ground, scale of the map and the contour interval required. It
varies from 20 m to 100 m. Closer intervals are required if ground level varies
abruptly.
The cross- sectional line need not be always be at right angles to the main line. This
method is ideally suited for road and railway projects.

c. Radial Line Method :-
In this method several radial lines are taken from a point in the area. The direction of each
line is noted. On these lines at selected distances points are marked and levels determined.
This method is ideally suited for hilly areas. In this survey theodolite with tacheometry
facility is commonly used.
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40

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