Module 4 Introduction to Surveying and Levelling.pptx

Definition of Surveying
• Surveying is one of the basic area in civil engineering which includes
linear and angular measurement of the relative positions of the points
on the surface of the earth.
• Linear and angular measurements enable the civil engineer to obtain
information of the piece of ground, land or plot in a locality.
• From this information; civil engineer or surveyor can locate the
boundaries of the plot or features and finally bring it on paper to a
suitable scale, which furnishes a further tool to prepare a layout plan in
which planning of any building project work can easily be done.

Objective of Surveying
• Surveying is very important branch or basic area of civil
engineering because starting any construction work of any structure
or project; the surveying of land or ground is done first of all.
• Surveying is the method of taking the measurement of the relative
positions of the points on, above or beneath the earth surface so that
the points may be represented on a map or plan.
• In short, surveying deals with the linear measurement and angular
measurement in horizontal plane and in vertical plane.

Objective of Surveying
• By the methods of surveying, points on the ground or land can also be
established from the predetermined angular and linear measurement.
• Surveying also includes determining the relative positions of points in
the vertical plane, which comes under the part of levelling.
• In levelling, vertical measurement or levels or elevations of relative
positions of points are found out and then contour map can be prepared
so as to know the ground profile of the earth surface or land on which
any structure is to be built.

Fundamental Principal of Survey
• The various methods of surveying are based on planning following
two main principles:
1. To work from whole to part
• This principle states that it is essential to first establish control
points with high precision and then establish minor control points.
• Any inner details can further be located within the minor control
points.
• To work from whole to the part means that entire area or a
very large from the area to be surveyed is first considered and
then its smaller parts are considered.

Fundamental Principal of Survey
• Working by this procedure enables to prevent the accumulation of
possible errors in the surveying work of larger area. The principle to
work from whole to part can be well understood by the following
example.
• Consider a very large area like a town to be surveyed as shown in Fig. 1
• First of all, control points A, B, C, D and E are fixed or located with
great care within the boundary of the area of town as shown in Fig. 1.
• The area which is obtained from these control points is divided into
number of triangles which are further sub-divided into small triangles
by the method of triangulation; e.g. Triangle CED is further divided
into small triangle 'pqr' as shown in Fig. 1.

• The details within these triangles are surveyed with less accuracy. This is
known as working from whole to the part.
• By this principle or system, accumulation of possible errors in the
surveying work can be prevented.
• It is noted that, if we start from small areas and then cover large area then
mistakes or errors may go on accumulating and finally affects the surveying
work resulting in less accuracy.
• City survey or town survey or topographical survey can more precisely be
carried out by this principle.

2. To fix or to locate a new point or station by at least two
independent measurements or processes
In surveying, the relative positions of points are located by measurements from at
least two points of reference whose positions are known.
In short, the position of new points from the two known points can be fixed or
located by taking (a) linear measurements (b) angular measurements or (c) both
linear and angular measurements.
In this method, two points are selected in the field and distance between them is
measured.
Then relative positions of the other points in the field can be located from these
two reference points.
For example, refer Fig. 6.3.2. From known positions of P and Q, the positions of a
new point 'R' is fixed or located by measuring any of the following:

2. To fix or to locate a new point or station by at least two
independent measurements or processes
i) By the perpendicular 'RS' and distance 'QS'. see Fig. 6.3.2(a).
ii) By the two lengths 'PR' and 'QR' see Fig. 6.3.2(b).
iii) By the angle 'a' measured at Q and length 'QR'. See Fig. 6.3.2(c).
iv) By the length 'QR' and angle 'B' measured at P. see Fig. 6.3.2(d).
By the two angles a and ẞ measured at Q and respectively see Fig. 6.3.2(e).

Classification of Surveying
1. Primary divisions of survey
i. Plane surveying
ii. Geodetic surveying
2. Secondary classification of surveying

Primary Divisions of Survey
• Primarily surveying can be divided into two classes.
• Plane surveying is that type of surveying in which the mean surface of
the earth is considered as a plane and the spheroidal shape is
neglected.
• Geodetic surveying : is that type of surveying in which the shape of
the earth is taken into account. All lines lying in the surface are curved
lines.

• The following are the various uses of surveys based on plane and
geodetic surveying.
1. Plane surveying
(1) It is useful for measuring the area of land or plot.
(2) It is useful for engineering, architectural, commercial, scientific,
military, navigational, etc purpose.
(3) It is used for both location as well as construction of different classes
of work.
2. Geodetic surveying
(1) To obtain accurate maps of wide areas and controls for all other
surveys.
(2) To obtain information regarding the positions of points, heights
above sea level.

Difference between Plane Survey and Geodetic Survey
Plane Survey Geodetic Survey
1 The surveying in which the mean surface of
the earth is considered as a plane and
spheroidal shape is neglected, is called as
plane survey.
The surveying in which the shape of the earth or
curvature of earth and all the lines lying in the
surfaces are being curved, is called as geodetic
survey. Geodetic Survey is also called as
trigonometrically survey.
2 Plane Survey is used for measuring the area
of land or plot.
Geodetic survey is used to obtain accurate maps of
wide areas and controls for all other surveys.
3 It is used for
engineering, architectural, commercial,
scientific, military. navigational purpose.
It is used to obtain the information regarding the
portion of points, heights above sea level. Hence it
is used for topographical, engineering, cadastral
etc.
4 In plane survey, small distance and area are
covered.
In geodetic survey; large distance and areas are
covered

Secondary Classification of Surveying
• Surveys may be classified under headings which define the uses or
purpose of the resulting maps.
(A) Based upon the nature of the field survey
(B) Classification based on the object or purpose of survey
(C) Classification based on instruments used or Methods employed

(A) Based upon the nature of the field survey
(1) Land surveying
(a) Topographical surveys
(b) Cadastral surveys
(c) City surveying
(2) Marine survey
(3) Astronomical survey

(1) Land surveying
(a) Topographical surveys
It is made to determine the natural features of a country such as river, streams,
lakes, woods, hills etc and such artificial features as roads, railways, canals,
towns and villages.
(b) Cadastral surveys
Cadastral surveys are made for fixing of property lines, the calculation of land
area, or the transfer of land property from one owner to another.

(1) city surveying
City surveying are made in connection with construction of
streets, water supply system etc.
(2) Marine survey
Marine survey or hydrographic survey deals with bodies of water
for purpose of navigation, water supply etc.
(3) Astronomical survey
It is used to determine the absolute location of any point or the
absolute location and direction of any line on the surface of the
earth.

(B) Classification based on the object or
purpose of survey
(1) Engineering survey
(2) Military survey
(3) Mine survey
(4) Geological survey
(5) Archaeological survey

(C) Classification based on instruments used or
methods employed
(1) Chain survey
(2) Theodolite survey
(3) Transverse survey
(4) Triangulation survey
(5) Tacheometric survey
(6) Plane table survey
(7) Photographic survey
(8) Aerial survey

What are applications of surveying?
I. Maps and plans of the existing area of land or ground can be prepared from
the field observations taken in horizontal plane.
II. Relative positions of the points on the earth surface can be or can be
established.
III. The horizontal distances between the different points can be found out and
finally plan or traverse of an area can be prepared by the method of
surveying.
IV. Alignment of road, railway line, electric tower line, tunnel, bridges, electric
poles and marine structure can be fixed by the method of surveying.

What are applications of surveying?
V. Levels or elevations of various points along the proposed road, railway track,
canal or earthen dam can be found out.
VI. Particular slope or gradient for water supply, drainage, gas line and for
roadwork can be laid.
VII. Contour maps can be prepared which give the correct idea of the ground
profile (i.e. undulations of ground) from which the projects such as dam,
canal, buildings, roads and railway track are further carried out. This is
known topographical survey.
VIII.Plotting of irregular boundaries of plots and existing structure on paper.

ix) Finding the horizontal distances with the help of tape, or electronic distance
meter depending upon the precision required.
x) Carrying out the survey on lakes, rivers, nala and sea to study the bed
profile. This is known as hydrographic survey.
xi) Finding out level difference between various points on the ground surface.
xii) Carrying out aerial photography of earth's surface with the help of aerial
cameras kept inside the airplane or helicopter. Aerial photographs make it
possible to get all information required and are useful for route surveys, town
planning, understanding forest cover. ground water hydrology.

xiii) Carrying survey in city areas to locate details like open area, streets,
buildings, water supply and sewer lines etc. This is known as city surveying.
xiv) Remote sensing: This is the most advanced method of surveying where
pictures of the earth surface are taken from unmanned satellites revolving
around the earth in orbits. These are called as satellite imageries which has
numerous applications to determine

(a) Agricultural soil,
(b) Cover of forests over an area,
(c) Investigation of rock,
(d) Environmental studies.
Plan
Definition: Graphical representation of a building structure like residential,
commercial, public, bridge, dam etc. to a smaller scale such as 1:20, 1:50,
1: 100 etc. is called as plan.
Map
Definition: Graphical representation of a very bigger land like land of city,
land of nation to a greater scale such as 1:1000, 1:5000, 1: 10000 etc. is
called as map. For example, map of Maharashtra, map of India, map of city
like Pune, Nashik

Difference between Plan and Map
Plan Map
1 It is the graphical representation of a
building structure like residential,
commercial, public, bridge, dam etc
It is the graphical representation of bigger land like
city land, land of state and nation.
2 It is drawn a smaller scale such 1:20, as
1:50,1:100 etc.
It is drawn is bigger scale such as 1:1000, 1:5000,
1:10000 etc.
3 For example:
1. Plan of residential building
2. Plan of culvert
3. Plan of swimming
For example:
1. map of Gujarat
2. Map of India
3. Map of Surat city
Unit of Measure
1. Plain scales
2. Representative Fraction (R.F.)

1. Plain scales
With the help of plain scale, it enables to read
only two dimensions or digits digits such as;
meter (m), kilometer (km), tenths of km, tenths of
meters and unit meters etc.
The plain scale can be constructed as follows:
Plain scale 1 cm = 10 m can be constructed to
read a meter.
Procedure
Take a line 10 cm long representing 100 m on the
ground.
Divide this line into ten equal parts. Again divide
the first on the left side into ten equal parts as
shown in Fig. 6.7.1.

In first division, each subdivision reads 1 meter.
Mark the zero between the subdivided part and undivided part and then
mark the figures 10, 20, 30, 40, 50 etc. to right side and left side of the
zero mark as shown in Fig. 6.7.1.
In Fig. 6.7.1, according to the construction of plain scale as 1 cm = 10 m;
42 m can be shown on it.

Representative Fraction (R.F.)
• The plan of the building structure or map of town or city cannot be
made full size on a drawing sheet.
• Therefore conveniently it is essential to draw these plans or maps to a
reduced size. This is called as drawing to scale.
• Definition: If a line of 1 cm long drawn on sheet or paper representing
30 m on ground, then this scale can be expressed as 1cm = 30 m i.e. 1
cm on drawing sheet and 30 m on ground. Such a scale is called as
plain sca

The scale can also be expressed by 'Representative Fraction' (R.F.)
The representative fraction can be defined as the ratio of distance on paper
to the corresponding distance on ground considering a fraction with unity as
its numerator, forming the representative fraction in such a way that both
numerator and denominator must be reduced to same unit.
R.F. = Distance on plan or map/Corresponding distance on ground
For example; If plain scale is 1 cm = 5m then R.F. to the scale can be obtained
as follows:
(1cm)/(5 * 100cm) = 1/500
R.F.= 1 : 500
Note: 1 : 500 means 1 cm = 500 cm such that both numerator and
denominator are reduced to same unit.

The plain scale can be converted to R.F as follows:
(i) Plain scale of 1cm = 10m;
R.F.= (1cm)/(10 * 100cm) = 1/1000
R.F.= 1 : 1000
(ii) Plain scale 1cm = 20m ;
R.F.= (1cm)/(20 * 100cm) = 1/2000
R.F.= 1 : 2000
(iii) Plain scale 1cm = 2km ;
R.F.= (1cm)/(2 * 1000 * 100cm) = 1/200000
R.F.= 1 : 200000

The following are some of the scales in the form
of R.F. recommended for survey maps:
i. City map or Cadastral Map, 1/1000 to 1/500
ii. Location maps, 1/2500 to 1/500
iii. Large - scale Maps, 1/10000 to 1/20000
iv. Topographical maps, 1/250000 to 1/25000

Introduction
• Chain Surveying is the type of surveying in which only
linear measurements are taken in the field. Linear
measurements are carried out for finding out
measurements in horizontal plane.

Methods
There are 3 methods of making linear measurements.
1- Direct Method.
In the case of direct measurements the distances are actually measured on the ground
with the help of a chain or tape.
2- Optical Method.
In this method no direct measurements are done but the observation are taken through a
telescope on a levelling staff and then these values are substituted in standard formulae
to obtain the horizontal distance. E.g. Tachometry or triangulation
3- E.D.M Method.
The E.D.M. is the nearest example of electronic methods where the distance are
measured with instruments that work on the principal of propagation of waves.
Distance up to many kilometers can be measured with great precision within no time by
employing this method.

Approximate Methods
• Pacing.
• Passometer.
• Pedometer.
• Odometer.
• Speedometer.
• Measuring Wheel.
Speedometer
pedometer

Method of Direct Measurements
A. Chaining
B. Instruments used in chaining
i. Chains
ii. Tapes
iii. Arrows
iv. Ranging Rods and Offset Rod
v. Pegs
vi. Plumb- bob

Types of Chains
• Metric chain
• Gunter’s chain or Surveyor’s chain
• Engineer’s chain
• Revenue chain
• Steel band or Band chain

A. Chaining
• In the method of chaining to denote horizontal distance, either a chain or a
tape is used for making direct measurements.
• A chain is less precise than a tape and therefore for works with precision a
tape is used.
B. Instruments used in chaining
(1) Chain and Tape
• The chain is made of straight links of galvanized mild steel wire of 4 mm
in diameter.
• The links are bent into rings at the ends because of which they offer
flexibility.
• The ends of the chain are provided with brass handle at both ends.
• The brass handle is joined to chain with a swivel joint. Handles serve as a
means to pull the chain on the ground.
• The length of the chain includes both the handles.
• At every one metre mark the chain is provided with a brass ring to indicate
a completed metre.
• Brass tallies are provided at every 5 m of the chain.

Taking measurements on chain
• Metric chains are made in lengths 20m and 30m. Tallies
are fixed at every five-meter length and brass rings are
provided at every meter length except where tallies are
attached.

• Each tally has different shape
which indicates either 5m, 10m or
15m, completed distance from any
of the ends of the chain. Refer Fig.
7.2.1(a).
• The chains are available in lengths
of 20m and 30m. A 20m chain
consists of 100 links of 20 cm
length each and a 30 m chain
consists of 150 links of 20 cm
length each.
• Brass tallies of variable shapes as
shown in Fig. 7.2.1(b) are provided
• In a 30 m chain, 5 m and 10 m
tallies are provided from both ends
of the handle with a 15 m tally at
the center.

Testing of the chain
• Before the start of the chaining work to measure horizontal distance,
it is necessary to ensure that the chain is of correct length.
• A chain may either be tested with reference to a standard chain or
with reference to a steel tape.
• Sometimes the chain is compared with a permanently established
gauge as shown in Fig. 7.2.2.

Adjustment of chain
While testing of chain if it is found that the chain is either too long or too short, then
the following adjustments shall be made:
If the chain is too long then the following adjustments can be carried out :
(a) The opened up joints are closed by hammer.
(b) The rings at the ends of the links may have turned into oval shape which are again
made rounded.
(c) Some of the links may be removed to reduce the length of chain.
If the chain is too short then the following adjustments can be carried out :
(a) The bent links are made straight.
(b) Rings are flattened by hammering.
(c) Some smaller size rings are replaced by large size rings.

Tapes
Tapes are used for more accurate measurements of length. Tapes are classified and
used based on material of
which they are made as follows:
Classification of Tapes
(1) Cloth or Linen tape
(2) Metallic tape
(3) Steel tape
(4) Invar tape

(i) Cloth or linen tape
• The linen tape can be used for taking subsidiary measurements of
offsets.
• Cloth or linen tapes are made of varnish strip of woven linen 12 mm
to 15 mm wide, calibrated in 'm' and 'cm’ on one side and feet inches
on the other.
• These tapes are light, flexible and handy and available in 10 m, 20
m, and 30 meters length.
• The ends of the tape are provided with small brass ring.
• It is noted that length of brass ring is included in the length of the
tape itself.
• The ring serves a purpose to stretch the tape on the ground for better
accuracy.
• A cloth tape or linen tape has following disadvantages.
• Affected by moisture and therefore shrinks.
• Changing of length while stretching.
• Not durable.
• Due to these disadvantages, there is less use in surveying work.

(ii) Metallic tape
• This type of tape is used for general
purpose measurements.
• It is also used for taking offsets, location
sketches etc. during linear
measurements.
• A metallic tape is made up of varnished
strip of fine brass, copper or bronze wires
so as to prevent twisting and stretching.
• It is better than linen tape.
• These types of tapes are available in
lengths of 5 m, 10 m, 15 m and 50
metres, fitted in a metal or a leather case
with a winding device.
• These tapes are calibrated in 'm' and 'cm'.

(iii) Steel tape
• Steel tapes are used for all types of
work where great accuracy and
precision is required.
• A steel tape is superior to a cloth or
metallic tape and consists of a light
strip of stainless steel of width 6 mm
to 10 mm.
• It is delicate and very light, therefore
shall be carefully handled.
• The tape must be wiped clean and
made dry after its use. Steel tapes are
available in 2, 5, 10, 30 and 50 metres
length.

(iv) Invar tape
• Invar tapes are used for linear
measurements of a very high degree of
precision and accuracy.
• The invar tape is made of alloy of nickel
and steel and has a very low coefficient of
thermal expansion.
• Due to least value of coefficient of
thermal there is no effect of temperature
on it, making the tape more precise.
These tapes are expensive and more easily
deformed than steel tape.

(2) Pegs
Pegs are made of timber or steel and
they are used to mark the positions of
the stations or terminal points of a
survey line.
Pegs are 15 cm long and are driven in
ground with the help of hammers.

Pegs
• Made of timber or steel.
• Used to mark the position of stations.
• Pegs are in length of 15 cm.

(3) Arrows
• When chaining is done for longer distances, to
count the number of chains, arrows are inserted
into the ground after every chain length measured
on the ground.
• At the end of the chaining work the number of
arrows utilized multiplied by the length of chain
gives the total length traversed by chain.
• Arrows are made of good quality hardened and
tempered steel wire of 4 mm in diameter.
• The length of arrow is 40 cm.
• One end of the arrow is made sharp and the other
end is bent into a loop to facilitate carrying of
arrows. Fig. 7.2.4 shows a 40 cm long arrow.

Arrows
• Arrows are made of tempered steel wire of diameter
4mm.
• One end of the arrow is bent into a ring of diameter
50mm and the other end is pointed.
• Its overall length is 400mm.
• An arrow is inserted into the ground after every chain
measured on the ground.

(4) Ranging Rods
• The ranging rods are circular in section and
generally 2 to 3m in length.
• These rods are painted with the alternate
bands of black and white or red and white
colours in length of 20 cm, so that they can
be seen at a longer distance at the time of
ranging.
• For better visibility, sometimes, coloured
flanges are provided at the top of the rod.
• An iron shoe is provided at the bottom of
ranging rod for fixing it firmly into the
ground.

Ranging Rods and Offset Rod
• Ranging rods are 2 to 3 m in length.
• Used for ranging some intermediate points on the survey line.
• Painted with alternate bands of black and white or red and white
colours.
• With length of each equalising 20 cm.

(5) Plumb bob
• A plumb bob is used to transfer the
points to the ground.
• It is also used to make ranging poles
truly vertical and to transfer points
from a line ranger to the ground.
• With the help of plumb bob,
cantering in prismatic compass,
theodolites and plane table is done.
See Fig.

Ranging
Q- What is Ranging? Enumerate various methods of ranging?
Definition : The method of locating or establishing intermediate points
on a straight line between two survey stations or between the two
fixed points is called as Ranging.
There are two methods of ranging:

(a) Direct method or Direct ranging
This method is employed in the field when the two ends of the survey lines are
intervisible.
Direct ranging can be done by two methods:
(i) Ranging by eye
• Consider two points A and B at the end of survey line which is spaced at a
distance greater than one tape length as shown in Fig. 7.3.1.
• For ranging by eye judgment, ranging rods are fixed at station A and station B.
• The surveyor stands half a meter back side of ranging rod at A in line with AB.
• The assistant then moves the ranging rod under the guidance of the surveyor
in such way that the ranging rod hold by the assistant is in line with AB at
point 'C' between A and B. See Fig. 7.3.2.

• Similarly other intermediate points are located by eye judgment.
• In this way, ranging by eye finally brings the intermediate points in a
straight line with respect to station A and station B.
• Surveyor has to guide his assistant by giving him some hand signals so
that assistant holding ranging rod finally comes in a line, between
station A and station B.
• Electric poles are located in a straight line by this method which is a
good practical example of the field work.
• Code of signals for ranging to be given by surveyor to his assistant are
tabulated in Table 7.3.1 (section 7.3.1).

(ii) Ranging by line ranger
Q. Explain with sketch, the use of line ranger. GTU-Sep. 2009, 2 Marks
Q. Explain the direct ranging with the use of Line Ranger. GTU-May 2016, 4 Marks
• The line ranger is a handy and light instrument by which the intermediate points between the two
ranging rods can be established. It consists of two plane mirrors or two right-angled isosceles prisms
placed one above the other as shown in Fig. 7.3.2.
• The diagonals of the two prisms are silvered so as to reflect the incident rays.
• The lower prism is fixed but the upper one is adjustable.
• This instrument can easily be held by the surveyor with handle provided at the bottom.
• When the two images of ranging rods coincide, then from the bottom of the handle, a small pebble is
dropped on ground, thus a required point can be transferred to the ground with respect to the line of
two ranging rods which are already fixed.
• Fixing the positions of electric poles in a straight line with the help of line ranger is good practical
example of field work.

Indirect Ranging or Reciprocal Ranging
Q. Define Reciprocal ranging.
Q. Explain the procedure of reciprocal ranging. GTU Jan. 2010, Dec. 2015, 5 Marks
Q. Explain reciprocal ranging. GTU-Dec. 2010, 4 Marks
Q. Explain with neat sketch the procedure for indirect ranging. GTU Jan. 2011, 3 Marks
Q. Explain reciprocal ranging with neat sketch. GTU-Dec. 2014, 5 Marks
This method of ranging is adopted when the two ends of a survey line are not visible from either of the
stations due to a hill or high ground between them. See Fig. 7.4.1. Point A is not visible from B and point B is
not visible from point A. Then to proceed in straight line between A and B. the process of indirect ranging is
done.

• As shown in Fig. 7.4.2 two surveyors station themselves at say M{1} and M{2}
approximately in line with AB. Person with ranging rod at M{2} can see M1,
and A whereas person with ranging rod at M{1} can see M{2} and B.
• Now Person at M_{2} will guide the person at M_{1} to come in line with M1,
and A on a new position M_{3}.
• The person on M_{3} will guide the person at M_{2} to come to a position
M_{4} Such that M_{3} , M_{4} and B are in one line.
• Ranging rods are fixed at M_{7} and M_{8} and then chaining continued along
the hill with reference to intermediate points M_{2} and M_{8}.

Principal of chain Surveying
The principal of chain surveying is chain triangulation.
Triangulation provides a skeleton or frame work consisting of a number of connected
triangles.
Since a triangle is the only simple lane figure which can be plotted by measuring its
sides alone in the field.
Definition: To get good results in plotting, the framework should consist of triangles
which are as nearly equilateral as possible. Such triangles are known as well
conditioned or well shaped triangles.
In such triangles no angle smaller than 30° and no angle greater than 120°.
Definition: Triangles having angles less than 30 or greater than 120 are known as ill
conditioned triangles.
Such triangles should always be avoided.
If they are unavoidable great care should be taken in chaining on plotting.

Survey Stations
A survey station is a prominent point on
the chain line and can be either at the
beginning of the chain line or at the end.
Stations are of two kinds :
1) Main
2) Subsidiary or tie.

• Definition: Main stations are the ends of the lines which command the
boundaries of the survey, line joining such stations are called the main
survey line or chain lines.
• However, subsidiary or tie stations can be selected well anywhere on the
chain line and subsidiary or tie line may be run through them.
• Stations are usually denoted with a small circle round the station point 'O'
• Main stations are denoted by capital letters and subsidiary or tie stations
by small letters e.g. AB or arb etc. survey lines are indicated by the letters
of stations e.g. AB, BC, ab, bc etc.
• The systems of lines of this triangles covering the area to be surveyed is
called the skeleton or frame work of survey.

Selection of Survey Stations
1. Survey stations must be mutually visible.
2. If possible survey lines should run roughly through a level ground.
3. The main lines should form well condition triangles.
4. Each triangle or portion of section must be provided with at least one check line.
5. As far as possible main survey line should not pass through obstacles.
6. If possible, a long line should run roughly through the centre and the whole length of area.
7. Survey line should be run to locate the details and to avoid long offsets.
8. The framework must have one or two base line.
9. If one base line is used, it must run along the length and through middle of the area. If two base
lines are used they must intersect to form a letter x.
The Field Book
Field book is a note book in which survey work is recorded. The chain line is represented either by a
ruled single line or by two lines.
Single line field book is used for large scale and the double line field book is used for normal work.
The chainages are entered in the column and on the either side of the chain line sketches of the
objects are drawn.
Following are the instruction given to a fresh trainee surveyor regarding the care and used of field
book for recording survey measurement.

1. Draw index map in the beginning of the work.
2. Enter chainages in the central column.
3. Indicate main survey stations by equilated triangles.
4. Each survey line should be recorded on a separate page.
5. Chainages of tie stations should be written clearly.
6. Offsets of the features should be written clearly.
7. You should face the forward direction while entering the readings i.e. objects
to the right of the chain should be entered to the right of the central column.
8. The features crossing the chain line are broken off on one side of the central
column and continued horizontally opposite on its other side.
9. The sketching of the objects is not to scale but in proportional.
10. Offsets measurements are written against the objects to which they refer.
11. Entries should be recorded in good quality pencil.
12. The field book should be kept neat and clean.

Field Work
Field work consists of following operation:
Operations of Field work
a) Reconnaissance
b) Marking stations
c) Location sketch
d) Running survey line

a) Reconnaissance
Definition: The preliminary inspection of area to be surveyed is called reconnaissance.
• The first principle of any type of surveying is to work from whole to part. Before starting
the survey measurements, the surveyor should walk around the area to fix best position of
survey line and survey station and prepare a neat sketch called an Index Sketch in the field
book showing the plan of area, principle features such as building, roads etc.
• He should see the intervisibility of survey stations also investigate various difficulties that
may arise and time required.
b) Marking stations
Stations are marked on the ground in such a way that they can be easily discovered during
the progress of work.
The following methods are adopted to mark the survey stations,
1. By driving wooden pegs.
2. Nails or spikes may be used in case of road.
3. By fixing ranging rod.
4. By a stone of any standard shape which may be embedded in the ground.

c) Location sketch
• Clear references must be given for each and every survey station so that any future work setting
out or checking work etc. can easily be done with reference to these stations.
• Hence location sketches of different objects with respect to survey station are drawn.
• A sketch showing location or reference of a station is drawn in the field book which includes north
direction and minimum two measurements taken from the some permanent object like temple,
building corner, or tree upto the survey station or survey peg. See Fig. 7.9.1.

Concepts of Base Line, Tie Line and Check Line
• In plain surveying, the area of land or ground is divided into number of triangles, then
linear measurements of the sides of the triangles are taken.
• There are no angular measurements.
• When the three sides of a triangle are known, then it can be plotted on a paper to a
suitable scale.
• Suppose the land shown in Fig. 7.10.1 is to be plotted, then first of all, marking of
stations P, Q, R, S is done at the periphery of land and then triangles A PQS and A QSR
are formed.
• In Fig. 'QS' is a base line. PQ, QR, RS, SP and ST are survey lines. UV is a tie line and PT is
a check line.
• Along the survey lines and tie lines, the interior details are marked by taking
perpendicular distances i.e. offsets and recorded in the field book which helps further in
plotting.
• Accuracy of surveying work after plotting can be checked by check line.

(a) Base line
Definition: The longest survey line passing through the centre of the area to
be surveyed is called as base line.
• In trigonometrical survey, base line should be laid on fairly level ground as
far as possible roughly through the centre of the area as shown in Fig.
• It fixes up the direction of all the survey lines.
• It is very important line because complete frame work of triangles is formed
on this line.
• The main purpose of selecting the base line in the centre of the area under
surveying work is to avoid possibly the accumulation of errors in a process
of triangulation.
• It should be measured with great care as the accuracy of the complete work
depends upon the base line.
• In Fig. 'QS' is a base line.

(b) Tie line
Definition: A line joining some fixed points as tie stations on the main survey
line or main survey line is called as tie line.
• In Fig. 'UV' is a tie line.
• When it is not possible to locate interior details from main survey lines of
the triangles, then a tie line is provided so as to locate the interior details.
• Tie line helps to check the accuracy of the framework.
(c) Check line
Definition: A line joining between the apex of triangles and some fixed point
on survey lines or on base line is called as check line.
• Accuracy of surveying work when plotted can be checked by check line.
• In Fig. 'PT' is a check line.

Offsets
Q. Define perpendicular offset and oblique offset. GTU-Jan. 2010, 2 Marks
Definition: Distances are measured from the survey lines to the object right or left of the survey line are called
as offsets.
Offsets are normally measured by metallic tape. For accuracy, steel tapes are used for measuring the offsets.
There are two types of offsets:
Types of offsets
(i) Perpendicular offsets
(ii) Oblique offsets
(iii) Short offsets
(iv) Long offsets
(v) Swing offsets
(i) Perpendicular offsets
Definition: When distances are measured at right angles (909 to the chain line, then such distances are called
as offsets or only offsets.

(ii) Oblique offsets
Definition: When distances are measured other than 90% then such
distances are called as oblique offsets.
In Fig. 7.11.2, 'QR' shows the oblique offset.
(iii) Short offsets
Definition: When offsets are set out by eye or by swinging the tape on chain
line, it should not be longer than 15 m such offsets are known as short
offsets.
• Offsets should be as short as possible, However limiting length of offset
depends upon accuracy desired, nature of ground, scale of plotting.
(iv) Long offsets
Definition: Offsets which are more than 15 m are set by optical square or
cross staff, such offsets are known as long offsets.
(v) Swing offsets
Definition: Offsets taken by swinging tape or chain is called swing offsets.

Obstacles in Chaining
• Various obstacles such as hills, ponds, lake, river, forest etc. are met with in
chaining.
• This obstacle to chaining prevent Chainman from measuring directly between two
points and give rise to problems, therefore special methods are employed in
measuring distance across the obstacles.
Obstacles to chaining may be classified as :
Classification of obstacles in chaining
(i) Obstacles to ranging but not chaining
(ii) Obstacle to chaining but not ranging
(iii) Obstacles to both chaining and ranging

(i) Obstacles to ranging but not chaining
Example: A hill or rising ground.
In this type of obstacle, the ends of a line are not intervisible. There may
be two cases of this obstacle.
1) Both ends of the line may be visible from intermediate points.
2) Both ends of the line may not be visible from intermediate points.

(ii) Obstacle to chaining but not ranging There may be two cases of this
obstacle :
(A) When it is possible to chain round the obstaclen example a pond, hedge
etc.
(B) When it is not possible to chain round the obstacle e.g. river.

(B) When it is not possible to chain round
the obstacle.
There may be several methods available, in case when it is not possible
to chain round the obstacle for example river. However a few are
described below:
Method 1
P and Q are two points on the chain line, PQ is the obstructed length.
Select another point R on the chain line. Erect a perpendicular PS and
RU and range Q S U in one line. Measure PR, SP and UR. Set out
perpendicular ST meeting T on UR.

Errors in Chaining
The errors that occur in chaining are classified as:
Errors in Chaining
1) Compensating errors
2) Cumulative errors
3) Personal mistake

(1) Compensating errors
Definition: The errors which are liable to occur in either direction and
hence tend to compensate are called compensating errors.
Compensating errors may arise due to the following reasons.
a) Incorrect length of chain or tape
b) Careless holding and marking
c) Displacement of arrows
d) Stepping operation may be done by dropping the stone instead of
plumbing.

(2) Cumulative errors
Definition: Errors which occur in the same direction and tend to add up is called as cumulative
errors.
• Such errors get accumulate and make the measurement too long or too short. Cumulative
errors may be positive or negative.
• When the measured length is more than the actual then positive cumulative error.
Positive errors may arise from:
(1) Incorrect length of chain or tape
(2) Sag in chain
(3) Inaccurate ranging
(4) The slope correction is not applied to the length measured along the sloping ground.
• When the measured length is shorter than the actual then the negative error negative errors
may arise from:
(1) Incorrect length chain or tape
(2) Careless handling and marking
(3) Variation in pull.

(3) Personal mistake
The following are the most common mistakes:
(i) Displacement of arrows
(ii) Reading of chain in wrong manner
(iii) Noting the readings in wrong way
(iv) Misreading.
• Errors in length due to incorrect chain.
• If the length of the chain used for measuring distance is incorrect, then
correction has to be applied to the measured distance to find the correct
distance.
• If the chain is too long, the measured distance will be less and the correction
is positive but if the chain is too short, the measured distance will be more
and hence the correction is negative

True length of line = L’/L × Measured length of line
Where,
L' = The incorrect length of a chain or tape
L = True length of a chain or tape
Error in area due to incorrect chain
True area =(L’/L) x Measured area

Conventional Symbols
• Sign Conversions or conventional symbols play a very important role
in topographical survey for representing the different features of the
ground or land.
• It gives the proper directional understanding and reading the various
topographical maps.
• Some of symbols recommended by ISI.

Tape Corrections
It is necessary to apply the following corrections to the measured
length of a line in order its true length.
1) Correction for absolute length
2) Correction for Temperature
3) Correction of Pull
4) Correction of Sag
5) Correction of Slope

1. Correction for absolute length
C=
𝑳𝑪𝒓
𝒍
Where,
Ct = True length
L = Measured length
l = Nominal length
Cr = Correction to Tap

2. Correction for Temperature
• Ct = a(Tm –To) L
• Where, Ct = Correction for Temperature
a = Coefficient of thermal expansion
Tm = The mean temperature during measurement
To = The Temperature at which the tape is standardized
L = Measured length

3. Correction of Pull
Cp = (P-Po)L/AE
Cp = Correction of Pull
P = Pull applied during measurement, n kilograms
Po= The pull under which the tape is standardized in kilograms
L= The measured length in m
A = C/s area of the tape in sq. cm.
E = The modulus of elasticity of steel

4. Correction of Sag
Cs = L1(W)2/ 24P2
Cs = The sag correction for a single span in m
Where
L₁ = The distance between supports in meters
W = Weight of the tape, in kilograms per meter
P = The applied pull in Kilograms

5. Correction of Slope
Slope correction= h2/2l
Where,
l = Length of any one slope
h = Difference in height between the ends of the slope

Introduction
• There are two methods for angular measurement:
1) Triangulation Survey
2) Traverse Survey

Triangulation Survey
In the past it was difficult to accurately measure very long distances, but it was possible to
accurately measure the angles between points many kilometers apart, limited only by
being able to see the distant become. This could be anywhere from a few kilometers, to
50 kilometers or more.
Triangulation is a surveying method that measures the angles in a triangle formed by
three survey control points. Using trigonometry and the measured length of just one
side, the other distances in the triangle are calculated.

Traverse Survey
DEFINITION:- Traversing is that type of survey in which a number of
connected survey lines form the framework and the directions and
lengths of the survey lines are measured with the help of an angle
measuring instrument and a tape or chain respectively.
TYPES OF SURVEYING
There are two types of traverse surveying. They are:
• Closed traverse: When the lines form a circuit which ends at the
starting point, it is known as closed traverse.
• Open traverse : When the lines form a circuit ends elsewhere except
starting point, it is said to be an open traverse.

Close Traverse Open Traverse
Suitability of Closed and Open travers
• The closed traverse is suitable for locating any existing structure, wood, boundaries of
plots or lakes etc.
• Open Traverse is suitable for locating long canals, roads or coastlines.

Compass
• A compass is a small instrument essentially consisting of a graduated
circle, and a line of sight.
• The compass can not measures angle between two lines directly but
can measure angle of a line with reference to magnetic meridian at
the instrument station point is called magnetic bearing of a line.
Instruments or angles Measurements
• For measuring angles in survey work the instruments commonly used
are (i) compass (ii) Theodolite and sometime sextant.
• The compass does not measure angle between two lines directly , but
measured bearing the theodolite whereas measures the angle between
two lines directly and also the bearing of the line.

Types of compass
• There are two types of magnetic compass they are as follows:-
• The Prismatic Compass
• The Surveyor’s Compass
• The Transit Compass

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: A 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 pivot head.
• 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 a degree.
• 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 eye sight.
• Eye vane: Eye vane is a fine slit provided with the eye hole at bottom to
bisect the object from slit.
• Glass cover: its 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.
• Spring brake or brake pin: to damp the oscillation of the needle before
taking a reading and to bring it to rest quickly, the light spring brake
attached to the box is brought in contact with the edge of the ring by gently
pressing inward the brake pin.

Temporary adjustment of prismatic compass
• 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.
This can be checked by rolling round pencil on glass cover.
• 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.

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 wrt
north pole.
• The enlarged portion gives actual
pattern of graduations marked on ring.
• Horizontal angle measured for any line
with respect to fix direction is called
bearings.
• N-S line is only a meridian line, so
bearing must be taken from N-S line.
NORTH
OBJECT B
A
SOUTH
LINE OF
SIGHT
90
180
270
0

The Surveyor`s Compass
• It is similar to a prismatic compass except that it has a only plain eye
slit instead of eye slit with prism and eye hole.
• This compass is having pointed needle in place of broad form needle
as in case of prismatic compass.

Working of Surveyor`s Compass
1) CENTERING
2) LEVELING
3) OBSERVING THE BEARING OF A LINE
• First two observation are same as prismatic compass but third
observation differs from that.
• 3) OBSERVING THE BEARING OF A LINE : in this compass ,the reading
is taken from the top of glass and under the tip of north end of the
magnetic needle directly. No prism is provided here.

Meridian
• Bearing of a line is always measured clockwise wrt some reference line or
direction. This fixed line is known as meridian.
• There three types of meridian:
1) Magnetic meridian: The direction shown by a freely suspended needle which is
magnetized and balanced properly without influenced by any other factors is
known as magnetic meridian.
2) True meridian : True meridian is the line which passes through the true north
and south. The direction of true meridian at any point can be determined by either
observing the bearing of the sun at 12 noon or by sun’s shadow.
3) Arbitrary meridian: In case of small works or in places where true meridian or
magnetic meridian cannot be determined, then ,any direction of a prominent
object is taken as a reference direction called as arbitrary meridian.

BEARINGS
• The bearing of a line is the horizontal angle which it makes with a reference
line(meridian).
• Depending upon the meridian , there are four type of bearings they are as
follows:
1) True Bearing: The true bearing of a line is the horizontal angle between the
true meridian and the survey line. The true bearing is measured from the true
north in the clockwise direction.
2) Magnetic Bearing: the magnetic bearing of a line is the horizontal angle
which the line makes with the magnetic north.
3) Grid Bearing: The grid bearing of a line is the horizontal angle which the line
makes with the grid meridian.
4) Arbitrary Bearing: The arbitrary baring of a line is the horizontal angle which
the line makes with the arbitrary meridian.

BEARINGS
TRUE
MERIDIAN
MAGNETIC
MERIDIAN
TRUE BEARING
MAGNETIC
BEARING
A
B
MN
TN
Line connecting true north
and true south along
curvature is called true
meridian.
Bearing measured
with respect to true
meridian is called true
bearing.
Line connecting magnetic north
and magnetic south along
magnetic flux direction is called
magnetic meridian.
Bearing measured
with respect to
magnetic meridian
is called magnetic
bearing.
Magnetic Declination : Horizontal
angel between magnetic meridian and
true meridian is called magnetic
declination.

Designation of bearing
• The bearing are designated in the following two system:-
1) Whole Circle Bearing System.(W.C.B)
2) Quadrantal Bearing System.(Q.B)

Whole circle bearing system(W.C.B.)
• The bearing of a line measured with respect to magnetic north in
clockwise direction is called magnetic bearing or whole circle bearing.
• Its value varies between 0ᴼ to 360ᴼ.
• The quadrant start from north an progress in a clockwise direction as
the first quadrant is 0ᴼ to 90ᴼ in clockwise direction , 2nd 90ᴼ to 180ᴼ ,
3rd 180ᴼ to 270ᴼ, and up to 360ᴼ is 4th one.
• Prismatic Compass

Whole circle bearing system(W.C.B.)

Quadrantal bearing system(Q.B.)
• In this system, the bearing of survey lines are measured wrt to north
line or south line which ever is the nearest to the given survey line
and either in clockwise direction or in anti clockwise direction.
• Surveyor Compass

Quadrantal bearing system(Q.B.)

Reduced bearing (R.B)
• When the whole circle bearing is converted into Quadrantal bearing ,
it is termed as “REDUCED BEARING”.
• 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.

conversion of WCB to RB.
Line W.C.B Between Rule For R.B Quadrant
AB 0◦ and 90◦ R.B=W.C.B NE
AC 90◦ and 180◦ R.B=180◦-W.C.B SE
AD 180◦ and 270◦ R.B=W.C.B-180◦ SW
AF 270◦ and 360◦ R.B=360◦-W.C.B NW
conversion of RB to WCB .
Line R.B Rule For R.B Quadrant
AB Nq1E R.B=W.C.B 0◦ and 90◦
AC Sq2E W.C.B=180◦-R.B 90◦ and 180◦
AD Sq3W W.C.B=180◦+R.B 180◦ and 270◦
AF Nq4W W.C.B=360◦-R.B 270◦ and 360◦

Fore bearing and Back bearing
• The bearing of a line measured in the forward direction of the survey
lines is called the ‘fore bearing’(F.B.) of that line.
• The bearing of a line measured in direction backward to the direction
of the progress of survey is called the ‘back bearing’(B.B.) of the line.
• The negative sign is used when the fore bearing exceed 180.
• The rule of B.B.=F.B.+/- 180 degree is applied only in Whole circle
bearing.

FB of line AB
BB of line AB
A
NORTH
NORTH
Θ1 Θ2
B
FB of AB = Θ1(from A to B)
BB of AB= Θ2(from B to A)
Remembering following points:
1) In the WCB system ,the differences
b/n the FB and BB should be exactly
180ᴼ. Remember the following
relation :
BB=FB+/-180ᴼ
+ is applied when FB is <180ᴼ
- is applied when BB is >180ᴼ
2) In the reduced bearing system the FB
and BB are numerically equal but the
quadrants are just opposite.

• Magnetic declination: The horizontal angle between the magnetic
meridian and true meridian is known as magnetic declination.
• Dip of the magnetic needle: If the needle is perfectly balanced before
magnetization, it does not remain in the balanced position after it is
magnetized. This is due to the magnetic influence of the earth. The needle
is found to be inclined towards the pole. This inclination of the needle
with the horizontal is known as dip of the magnetic needle.
• Local Attraction
• Method of correction for traverse:
• First method: Sum of the interior angle should be equal to (2n-4) x 90.
if not than distribute the total error equally to all interior angles of the
traverse. Then starting from unaffected line the bearings of all the lines
are corrected using corrected interior angles.
• Second method: Unaffected line is first detected. Then, commencing
from the unaffected line, the bearing of other affected lines are
corrected by finding the amount of correction at each station.

LEVELLING
What is Levelling?
 Use of Levelling
 Levelling Terminology
Types of Levelling
 Geometric Levelling
 Trigonometric Levelling
 Precise Levelling

What is Levelling?
Levelling, is the process of measuring, by direct or indirect
methods, vertical distances in order to determine elevations.

In the context of measurements, levelling is used for the
following purposes:
Referencing of Points:- To determine and check the vertical
stability of the point with respect to reference points
(benchmarks) in its immediate vicinity.
Connection to GPS Reference Points:- To determine its regional
stability and to separate sea level rise from vertical crustal
motion, the point should be connected via GPS to reference
stations fixed in a global co-ordinate system.
Uses of Levelling

Connection to National Levelling Network: -Mean sea level is used to
define vertical datums for national surveying and mapping , hence the
point must be connected to the national levelling network. Connection
to the network will also allow all points to be connected to each other,
providing information on spatial variations in mean sea level.
Uses of Levelling

Levelling Terminology
• Geoid; is a surface coinciding with mean sea level in the
oceans, and lying under the land.
• Level surface; is a curved surface that at every point is
perpendicular to the plumb line.
• Level line; is a line in a level surface, therefore a curved line.
• Mean Sea Level (MSL): is the average height of the sea’s
surface for all stages of the tide over a 19year period.

•Datum:- is a level surface to which elevations are referred
(for instance mean sea level).
•Elevation is the vertical distance from a datum (usually mean
sealevel) to a point or object.
•Bench Mark (BM) is a relatively permanent object, natural or
artificial, having a marked point whose elevations above or
below an adopted datum is known or assumed (metal disks
set in concrete, large rocks, non movable parts of fire
hydrants, and curbs
Levelling Terminology

Types of Levelling
• Geometric Levelling :- In geometric levelling the difference of
height between two points is determined by differences of readings to
the levelling rod placed on those points. The readings are made with a
levelling instrument.

• Trigonometric Levelling :- The difference in elevation
between two points isdetermined by measuring distance
(slope or horizontal) and vertical angle.

Precise Levelling :- is a particularly accurate method of geometric levelling
which uses highly accurate levels and with a more rigorous observing
procedure than general engineering levelling.In precise levelling we aim to
achieve high orders of accuracy such as 1 mm per 1 km traverse.

Errors in Levelling
Collimation Error:- Collimation error occurs when the
collimation axis is not trulyhorizontal when the instrument is
level.The effect is illustrated in the sketch below, where the
collimation axis is tilted witrespect to the horizontal by an angle

Errors in Levelling
Earth Curvature:- Due to the curvature of the Earth, the
line of sight at the instrumentwill deviate from a
horizontal line as one moves away from the level.

Errors in Levelling
Refraction:-The variable density of the Earth’s
atmosphere causes a bending of the rayfrom the staff to
the level.

Testing and Adjustment of a Level
Determining Collimation Error
Collimation error is much more significant than the other
errors. It should be kepsmall as possible so that one need not be
too precise in ensuring that fore and bsights are of equal length.
It is possible to determine the collimation error and reduce its
size using Two-peg test.
There are three steps involved in this procedure:

1. Set out and mark on the ground two point some 30m apart. Set
up the level exactly mid-way between them

2. Next, move the level to a position just beyond the fore staff
position (about 5m):

3. The difference dh:-Testing and Adjustment of a Level dh2- dh1
can be used to calculate what the true back sight reading would
be for the second setup, if collimation error were not present:
The purpose of the adjustment is to reduce the size of this
error. If the discrepancy dh2 – dh1 can be reduced to around 2mm
this is perfectly adequate, provided sight lengths are there after kept
reasonably similar.

1. Set out and mark on the ground two point some 30m apart. Set
up the the level to a position just beyond the fore staff position
(about 5m):

2. The difference between A and B:

LEVELLING
 Errors in Levelling
• Collimation Error
• Earth Curvature Error
• Refraction Error
 Testing and Adjustment of a Level
• Determining Collimation Error

Introduction to Theodolite
Definition: Theodolite is most accurate instrument used for
measurement of horizontal and vertical angle.
• It can also be used for various other purposes such as laying off
horizontal angles, prolonging survey line, determining difference in
elevation, locating points on a line, establishing grade etc.

Classification of Theodolite
Theodolite are primarily classified as :
Classification of Theodolite
(i) Transit theodolite
(ii) Non transit theodolite
Theodolite can also be classified as :
(i) Vernier theodolite (ii) Micrometer theodolite
(i) Transit theodolite
Definition: The theodolite in which the telescope can be revolved through a complete
revolution about its horizontal axis in a vertical plane is known as Transit Theodolite.
(ii) Non transit theodolite
Definition: The theodolite in which the telescope is mounted in such a manner that the line of
sight cannot be reversed by revolving the telescope is known as Non Transit Theodolite.
Now a days transit theodolite is most commonly used and the non transit theodolites have
become obsolete.

Components of Transit Theodolite (20")
and their Function
A transit theodolite essentially consists of following:
Components of Transit Theodolite
1. The Levelling head
2. The two spindles
3. The lower circular metal plate
4. Vernier plate or upper plate
5. Telescope
6. The level tube
7. The standards
8. The Vertical circle
9. The Vernier frame
10. The compass

1. Levelling head
The levelling head comprises two parts.
i) A levelling base i.e. tribranch and trivet plate fitted with foot screws for
levelling.
ii) Shifting bead or movable head is provided to center the instrument quickly
and accurately.
Function of levelling head:
Levelling head supports the main working parts of the instrument and screws on
to a tripod.
2. Two spindles
There are two spindles or centers one inside the other.
The outer axis is hollow to fit inner spindle.
Inner spindle is solid and conical.
Function: Spindles forms the vertical axis of the instrument.

3. Lower circular metal plate
The outer spindle is attached to the lower plate.
Lower plate is also called as scale plate.
The edge of the lower plate is levelled.
The edge is silvered and graduated from 0° to 360° in a clockwise direction.
The horizontal circle may be graduated to:
(a) Degrees and half degrees
(b) Degrees and thirds of a degree
(c) Degrees and sixths of degrees,
depending upon the size of instruments.
4. Vernier plate or upper plate
The upper plate is attached to the inner spindle.
The upper plate carries two verniers with magnifiers placed 180° apart for reading horizontal angles.
The upper plates also carries standards used for supporting the telescope and sprite level used for levelling the
instrument.
Function of lower plate and upper plate is, to the measurement of horizontal angles.
5. Telescope
The telescope is fitted at the center and at right angle to the horizontal axis.
Function: To see the object sighted clearly.

6. The level tube
The two level tubes are placed at right angles to each other. Of the two tube one is
fixed on the upper surface of the vernier plate and The another is parallel to the
horizontal axis.
Function: The level tube is used for levelling the instrument.
7. The standards
Definition: A frame stand upon the vernier plate to support the horizontal axis is
known as the standard.
8. Vertical circle
It is attached to the horizontal axis of the telescope.
It is usually divided into four quadrants (but in some instruments it is graduated
continuously from 0° to 360°).
The graduation in each quadrant are numbered from 0° to 90° in opposite directions.
The sub-division of the vertical circle are similar to those of horizontal circle.
9. Vernier frame
It is carrying an index and verniers or micrometer to measure vertical angles.
The following parts are also essential features of theodolite:

Vernier frame
(a) Lower clamp and lower tangent screw
(b) A upper clamp and upper tangent screw
(c) Plumb bob
(d) Compass
(e) Diaphragm
(f) A vertical circle clamp and tangent screw

(a) Lower clamp and lower tangent screw
• Lower clamp, clamps the lower plate and outer spindle to the leveling base.
• The lower tangent screw enables finely circular motion of it.
(b) A upper clamp and upper tangent screw
• It clamps the upper plate to lower one. Upper tangent screw enables finely controlled circular motion about vertical
axis.
(c) Plumb bob
• To center the instrument exactly over a station mark, a plumb bob is suspended from the hook fitted to the bottom of the
central vertical axis.
(d) Compass
• A circular or trough compass may be mounted on the vernier plate between the standards.
• Trough compass is used to indicate the N direction.
• Where circular compass can be used to indicate the N direction as well as to observe bearings.
(e) Diaphragm
• Diaphragm with cross hairs is provided in telescope to give a definite line of sight.
• It is stadia type diaphragm.
(f) A vertical circle clamp and tangent screw
• A vertical circle clamp, clamps the vertical circle and, telescope
• Its tangent screw enables a finely controlled circular movement to be given to the combined. telescope and circle about
the horizontal

Terms Used in Manipulating a Transit Theodolite
(1) Centering
(2) Transiting or Plunging of Telescope
(3) Face right
(4) Face left
(5) Face right observation
(6) Face left observation
(7) Telescope normal
(8) Telescope inverted
(9) Swinging the telescope
(10) Changing face
(11) Transit station
(12) Line of collimation
(13) Horizontal axis
(14) Axis of telescope
(15) Bubble line or axis of bubble tube
(16) Transit line

(1) Centering
The process of setting the instrument exactly over a station point is
known as centering.
Centering can be done with the help of plum bob, by suspending it to a
hook attached to the underside of the vertical axis.
(2) Transiting or Plunging of Telescope
The process of turning the telescope through 180° in a vertical plane
about its horizontal axis.

(3) Face right
When the vertical circle of a theodolite is on the right position with respect to the
observer while taking reading, the position is called face right..
(4) Face left
When the vertical circle of a theodolite is in the left position with respect to the
observer while taking reading, the position is called face left.
(5) Face right observation
It is the observation of an angle made with the face of the vertical circle on the
right of the observer.
(6) Face left observation
It is the observation of an angle made with the face of the vertical circle on the
left of the observer.
(7) Telescope normal
The position of telescope with the face left is known as telescope normal.

(8) Telescope inverted
The position of telescope with the face right is known as telescope inverted.
(9) Swinging the telescope
Swinging the telescope is turning the telescopic in a horizontal plane. Right
swing means rotating the telescopic in clockwise direction. Left swing means
rotating the telescopic in anti-clockwise direction.
(10) Changing face
It is the process of bringing the vertical circle to right of the observer, if
originally it is to the left, and vice versa.
(11) Transit station
The over which the transit theodolite stands and is centred when in use.

(12) Line of collimation
It is also known as line of sight. It is an imaginary line joining the intersection of
the cross hairs of the diaphragm to the optical centre of the object glass and its
continuation.
(13) Horizontal axis
The axis about which telescope can be rotated in a vertical plane.
(14) Axis of telescope
It is the line joining the centre of eye piece to the optical centre of object glass.
(15) Bubble line or axis of bubble tube
It is a straight line tangential to the longitudinal curve of the level tube at the
centre of bubble.
(16) Transit line
It is a straight line between two transit stations. Syllabus Topic: Introduction to
Total Station.

Total Station
Definition: An electronic total station means an E.D.M. and a
digital theodolite built as one unit.
•The total station is powered by small rechargeable batteries
and built into its memory are a number of self- contained
functions which include the measurement of slope, distance,
horizontal distance, vertical distance.
•There is a data recording module which is also called as
electronic field book. This data recording module records the
data and additional information. In total station, field survey
data consists of the angles, distance and related information is
stored in electronic field book.

Advantages of Total Station over Dumpy Level and Theodolite
• With total station, distance is measured by Instrument itself as total
station consists features of EDM, thus accuracy increases.
• It is digital instrument which gives the direct reading personal mistake
can be eliminated.
• There is a data recording module which is also called as electronic field
book. This data recording module records the data and additional
information.
• The total station is powered by small rechargeable batteries and built
into its memory are a number of self- contained functions which
include the measurement of slope, distance horizontal distance,
vertical distance.

Use of Total Station
1. With the help of electronic total station, measurement of slope distance,
horizontal and vertical distance can accurately and precisely found out.
2. Electronic total station gives the complete basic surveying exercise in order
to appreciate how land survey measurements can be used in support of
engineering construction and environmental restoration activities.
3. Vertical angle and horizontal angle are accurately measured by electronic
total station.
4. Total station for levelling classified as the indirect levelling method and
since it is judged that the method can maintain the considerable accuracy,
now it has been increasingly used for many public works as road. airport
and city etc.

Following are special features of total station.
A. High accuracy and long measuring range
B. Versatile application programs
C. Enhanced absolute encoder
D. Superior water-resistant and dust proof
E. No worry about sudden bad weather

A. High accuracy and long measuring range
(1) Higher accuracy: ± (2 mm + 2 ppm)
(2) Long measuring range with mini prism is 0.9 km.
Long measuring range with single prism is 2 km.
Long measuring range with 3 prism is 2.7 km.
B. Versatile application programs
(1) On board data collection, stakeout / survey road calculation, and many more
functions.
(2) Integrated alphanumeric key realizes the quicker operation.
(3) Large internal memory up to 24000 points.
C. Enhanced absolute encoder
Adopted absolute encoder, which need not require zero set and it can also realize
stable measurement with less reading error.
D. Superior water-resistant and dust proof
E. No worry about sudden bad weather

Component Parts of Total Station
a) Optical plummet
b) Display
c) Battery compartment
d) Leveling tube
e) Levelling screws
f) Vertical clamp
g) Telescope
h) Horizontal clam

Introduction to GIS
GIS
Q. Explain with sketch GIS and its components? State its objectives. GTU-Sept.
2009, 7 Marks
Q. State and explain the components of GIS. GTU-Jan. 2010, Dec. 2011, 7 Marks
Q. Explain Geographical information system. GTU-Dec. 2010, 5 Marks
Definition: Geographic information system (GIS) is computer software which
gives information of any discipline.
GIS can present many layers of different information. Hence GIS technology is
latest and one of the hottest new research tool in academia today.
Surveyors and engineers understand the importance of geographic data.

•A Geographic Information System (GIS) is not one
thing, nor a single analysis, but rather a collection of
hardware, software, data organizations and
professionals that together help people to
represent and to analyze geographic data.
•A GIS can combine geographic and other type of
data to generate maps and reports, enabling users
to collect, manage and interpret location-based
information in a planned and systematic way.

Key Components of GIS
Q. What are the key components of GIS. Describe them briefly. GTU-Dec. 2011, 7 Marks
The key components of GIS are as follows:
1. Geographic data
2. Method
3. Hardware
4. Software
5. People

1. Geographic data
• The geographic data includes the data related to the various types of features such as
houses, population, rivers, mountains, climate, soil, boundaries, oceans, forest etc.
streets, state
• The geographic data can be collected from the various sources like public agencies,
satellite images, manual field surveys etc. and this collected data is then stored in the
forms of digital maps.
• These digital maps can store the maximum information and provide more details
related to any features than the paper maps.
Types of geographic data
(i) Spatial data
(ii) Non-spatial data or Attributes
(iii) Hybrid data

(i) Spatial data
The spatial data depicts the geographical features of a place using symbols like a
point on a map can able to give the location of a college in an area.
(ii) Non-spatial data
It is also termed as 'attributes'. It depicts the additional information about the
spatial data such as amenities in the college, facilities in the school and the
number of rooms in the school which depicted by the spatial data.
(iii) Hybrid data
• It is a combination of spatial data and non-spatial data.
• Hybrid data Spatial data + Non-spatial data. = Location in case of spatial data
and features of a school and population covered under this school are combined
together and named as hybrid data.

2. Method
• After collecting the geographic data, next step is method in which
data is organized in a structured way for easy retrieval, editing and
analysis.
• The method of organizing data is known as a data model. Data model
can be organized just like the books are arranged on bookshelf in a
library. The method of data structuring may be different from project
to project.
• While handling and analyzing large volumes of data, it is more
essential to maintain the accuracy of data for correct analysis.
• Data structuring in method can be illustrated by giving the example as
shown in fig in which unorganized the books are organized by keeping
them properly in bookshelf.

3. Hardware
• Hardware is also key components of GIS; which require powerful computer hardware
which can support its massive database and huge images.
• Processing speed of a CPU must be more enough to run the software for GIS use and
also ram requirements in GIS should be more higher due to very large size of database
and images. The recommended size of ram is 128MB.
• To store the GIS data, secondary memory must be large. System can also be supported
with external storage media such as CD-ROMS and tape drives.
The main input devices which are required for GIS are as follows:
(i) Monitors
(ii) Printers
(iii) Plotters
(iv) Film recorders
Proper installation and configuration of each hardware component is important since
the hardware is an important component for the performance in GIS.

4. Software
The software is needs for GIS. Software comprises the operating system and GIS application software.
Windows 9x and later and UNIX are the two main operating system in GIS. Software gives the several mapping and
analyzing tools in GIS application.
Types of GIS software are available in market are:
(i) Auto CAD map from Autodeck Inc.
(ii) PCI Geomatics, Geomedia and TNT
(iii) Arc view, Arc / Info and Arc Ims from ESRI Inc.
(iv) Free software such as GRASS
(v) Manifold from Manifold corporation (vi) MapInfo professional and MapXtreme from MapInfo corporations.
5. People
• People are the most important component because of the most resources which help GIS so as to achieve the
variation applications.
• People are responsible to set the framework for computer hardware, software and process data for analysis for
GIS which is applicable in a university, business or government organization.
• A group of people conduct surveys and collects data. Another group of people analyses the raw data, digitizes it,
checks for errors, and edit it. Another team give support to protect data, troubleshoot and find the solution for
complex analysis.
• Next team of people provides software support and updates of the software whenever the new and improved
methods and techniques are employed.
• There are trained programmers who develop and provide user interfaces for the end users. Another team
specializes in the study of systems design.

Applications of GIS
1. GIS is used to improve organizational integration.
A GIS can link data sets together by common location of data, such as addresses,
which help department and agencies to share their data. By creating a shared
database, one department can get benefit from the work of another. In GIS, data can
be collected once and used many times.
2. GIS is used to make better decision.
The old adage "better information leads to better decision" is true for GIS. A GIS is not
just an automated decision making system but a tool to analyze and map data in
support of the decision making process.
3. GIS is used for making maps.
GIS is flexible enough to map of any kind of terrain; even the human body. GIS can
map any data we with to make. For example, GIS is used for mapping in which one
can find individual feature of any object an the land like building antennas, towers
and landscape etc.

4. GIS is used for every organizations of the defence industry is many nations around the world.
5. Surveyor use precise instruments, procedures and computations to accurately locate and
define geographic features while conducting field survey that range from cadastral to
engineering construction layout.
6. GIS is used as an interface for integrating and accessing massive amounts of location-based
information in the public safety market.
7. GIS software to study epidemiology; look at health care facilities and map any system that is
visual or spatial including inside a patient body.
8. GIS helps students and teachers engage in studies that require and promote critical thinking,
integrated learning and multiple intelligences at any grade level.
9. Architect makes the design, planning in proper and precise way quickly with the help of GIS.
10. GIS provides the analytical capabilities that form the hub of successful precision agriculture
system. GIS lets farmers perform site-specific analyses of agronomic data.
11. GIS technology enables telecommunications professionals to integrate location-based data
into analysis and management processes in network planning and operations, marketing and
sales, customer care, data management and many other planning and problem-solving tasks.
12. GIS is used in libraries and museums, in education, in conservation of water and wastewater,
transportation, in universities, in mining and earth sciences and in other so many institutions and
organizations.

GPS
Q. Write a short note on "Global positioning system“ GTU-May 2009, 4
Marks
Q. What is GPS? GTU June 2010, 2 Marks
Definition: Global positioning system (GPS) technology is a fast and
accurate method of determining the locations of any point of interest
anywhere on the face of earth of any time during the day or night.
The technology collects and processes signals from satellites in orbit
around the earth to determine the location of points of interest on the
ground.

Types of GPS
There are the basic types of survey grade system in GPS.
(i) Single Frequency
This type of surveying with a single frequency system is called as 'static
mode' GPS surveying.
(ii) Dual Frequency
Dual frequency systems only require post processing when operating in
static or fast static.

Classification of GPS Applications
(i) Surveying and mapping on land, at sea and from the air. The applications
are of relatively high accuracy, for positioning in both the stationary and
moving media. It includes geophysical and resource surveys, GIS data
capture survey etc.
(ii) Land, sea and air navigation, including enroute as well as precisions
navigations, cargo monitoring, vehicle tracking etc.
(iii) Search and rescue operations including collision avoidance.
(iv) Spacecraft operations
(v) Military applications
(vi) Recreational uses, on land, at sea and in the air
(vii)Other specialized uses, such as time transfer, altitude, determinations,
automatic operations etc.

Applications of GPS
Q. Explain GPS use in Civil Engineering field. GTU June 2010, 2 Marks
Following are the applications of Global Positioning system (GPS) widely used in any field of interest.
1. Determining the boarders, making existing utilities like highway, municipal amenities
photogrammetric and private site specific projects make then more dense or compact.
2. GIS data acquisition.
3. Monitoring, well, soil bring and other types of sampling locations.
4. Establishing state plane coordinates or geodetic coordinates.
5. Used in 'As-Built Survey and Topographic survey.
6. Used for mine exploration.
7. Used in Baseline survey and traverse control survey or traverse verification surveys.
8. Used in natural resource mapping.
9. Used in communication tower site survey and certifications.
10. Used in construction stakes out-utilities, highways, facilities, pilling etc.

Remote Sensing
Q. Briefly discuss about remote sensing. GTU Dec. 2015, 3 Marks
Definition: Remote sensing is a method of collecting and interpreting
information about terrain and other objects from a distance without being in
physical contact with the objects.
• Remote sensing involves the use of electromagnetic energy for the
characteristics determination of the object.
• In remote sensing, the imagery is obtained with a sensor. Special techniques
are used in remote sensing to process and interpreted remote sensing
imagery to obtain conventional maps, resource surveys etc.
• It collects information about geology, geography. forestry agriculture etc. and
has a vast application in exploration of natural resources.
• Remote sensing has application in the study of natural hazards such as earth
quakes, landslides and land subsidence.

Electromagnetic Energy
Electromagnetic energy is a form of energy which moves with the velocity of light.
The sun and various artificial sources radiate electromagnetic energy of variable
wavelengths.
This energy can be detected only when it interacts with matter changes in
electromagnetic energy takes place when it interacts with the earth's surface and the
environment. Remote sensing detects these changes and the data obtained is used
for determination of the characteristics of the earth's surface.
Passive system: The system in which sum and earth's materials are used as a natural
sources so as to radiate electromagnetic energy of variable wavelength is called as
passive system.
Active system: when the system in which irradiance from artificially generated
energy sources such as radar is used then it is called as active system. The
atmosphere affects the electromagnetic radiation in two ways:
Atmosphere affects the electromagnetic radiation
1. Scattering
2. Absorption

1. Scattering
Scattering of the electromagnetic radiation is caused by the molecules of gases, dust and
smoke in the atmosphere.
2. Absorption
Molecules of Ozone, CO, and water vapour in the atmosphere absorb some of the
electromagnetic radiation.
Interaction of electromagnetic radiation with matter: Electromagnetic radiation striking the
matter on earth's surface is called incident radiation.
The type of matter may change the characteristics of the incident radiation, such as intensity,
direction, wave length and phase.
The remote sensing systems are designed to detect and record these changes Fig. 9.16.6
shows the Electromagnetic radiation with matter and its interaction in five ways.
Electromagnetic radiation interaction
1. Transmission
2. Absorption
3. Emission
4. Scattering
5. Reflection

1. Transmission
Incident radiation which passes through the matter.
2. Absorption
Incident radiation absorbed by matter.
3. Emission
Emission is the energy emitted by the matter.
4. Scattering
Rough surfaces cause scattering.
5. Reflection
Some of the electromagnetic energy is reflected from the surface of
the matter.

Stages in Remote Sensing System
Q. Describe briefly the six elements involved in Remote sensing
process. GTU-Jan. 2013, 7 Marks
The remote sensing system consists of six stages:
(1) Energy source
(2) Propagation of energy
(3) Interaction with matter
(4) Return signal
(5) Recording
(6) Supply of information

Procedure
(1) The source produces electromagnetic energy.
(2) The energy from the source propagates to the
target.
(3) The energy received by the target interacts
where it is either transmitted, absorbed,
scattered, emitted or reflected from the target.
(4) The return signal is set to the sensor which
responds to all wave lengths.
(5) The data recorded is then processed for useful
interpretation.
(6) information about the target obtained from
the remote sensing is made available to the users
in the desired form.

Principle of Remote Sensing
• Remote sensing based on the following principle. "Sensing the Earth's surface from space by
making use of the properties of electromagnetic waves emitted, reflected or diffracted by the
sensed objects by using natural resource management, land use and artificial resources".
• The passive remote sensing system depends upon the strongest source of EM energy i.e.
Sun. The passive remote sensing measures energy which is either reflected or emitted from
the earth's surface features. But active remote sensing system uses their own energy source.
• The electromagnetic energy from the source passes through atmosphere to the earth's surface
and it get reflected from the earth's surface and it again pass. through the atmosphere to the
sensors.
• This is the principle of energy interaction in atmosphere and earth's surface features.
• The wave length and spectral distribution of energy is modified by the atmosphere to some
extent and this modification varies with respect to wave length.

Applications of Remote Sensing
(1) Resource exploration
(2) Environmental application
(3) Land use and land cover analysis
(4) Locating natural hazards

(1) Application of remote sensing in resource exploration
• Remote sensing has been successfully used in exploration of non-renewable resources such as minerals and
fossil fuels, and deposits of oil.
• The geological features can be studied in detail by remote sensing method like faults in rocks and geothermal
reservoirs in them.
(2) Environmental application of remote sensing
• Remote sensing gives environmental information about the atmosphere, continents and oceans.
• Behaviours of the ocean such as circulation, productivity and sea ice distribution could be properly studied by
remote sensing.
• Hydrologic phenomena such as cloud-motion, precipitation, freeze, hurricanes can be studied by remote
sensing.
(3) Application of remote sensing for land-use and land cover analysis
• For planning purposes land use and land cover should be known so as to locate vacant pieces of land.
• Land use means the purpose for which the land is used and land cover means the vegetation cover on the surface
of earth.
• Remote sensing is useful for mapping land use and land cover.
• By remote sensing large areas can be studied. Mapping of inaccessible areas can be done effectively. This
information is useful for forestry, agriculture and urban growth.
• Difficulty while working with remote sensing imageries is that, sometimes it becomes extremely difficult to
distinguish images of different land use.

Module 4 Introduction to Surveying and Levelling.pptx

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Similar to Module 4 Introduction to Surveying and Levelling.pptx

Similar to Module 4 Introduction to Surveying and Levelling.pptx (20)

More from SilasChaudhari

More from SilasChaudhari (12)

Recently uploaded

Recently uploaded (20)

Module 4 Introduction to Surveying and Levelling.pptx