ENGINEERING ADDA 72 / VIP ENGINEERING LOKSEWA

CENTRAL LEVEL PSC EXAM FOR SUB-ENGINEER

 ENGINEERING ADDA 72 / VIP ENGINEERING LOKSEWA

SURVEYING
OBJECTIVE
• 2 MCQs : each of 2 marks  2 x 2 = 4

SUBJECTIVE
1 Short Question of 5 marks : 1 x 5 = 5
Probability of 1 long question of 10 marks
ENGINEERING ADDA 72 / VIP ENGINEERING LOKSEWA

JOB BASED KNOWLEDGE: SYLLABUS

ENGINEERING ADDA 72 / VIP ENGINEERING LOKSEWA

OBJECTIVE SYLLABUS cont…

SUBJECTIVE SYLLABUS
 1.1 GENERAL
• Definition of Surveying:
Surveying, is defined as “taking a general view of, by
observation and measurement determining the
boundaries, size, position, quantity, condition, value etc. of
land, estates, building, farms, mines etc. and finally
presenting the survey data in a suitable form”.

The process of surveying is therefore in three stages namely:

• (i) Taking a general view
• (ii) Observation and Measurement
• (iii) Presentation of Data
 Primary Divisions of surveying
• Surveying may be divided into two general classes:
1. Plane surveying and 2. Geodetic surveying.

• Plane Surveying: Plane surveying is the type of surveying in which mean

surface of earth is considered as plane and curvature of the earth is
neglected, as the survey extends over small area. Surveys covering an area of
upto 250 sq.km may be considered as plane survey. In this survey, line
connecting any two points on the earth surface is considered as straight line
and angle between these lines as plane angle. Plane survey is used for layout
of canals, highways, railways, construction of bridges, dams, buildings etc.

• Geodetic surveying: Geodetic surveying is also called trigonometric surveying.

In this survey it is necessary to take into account curvature of the earth.
Geodetic survey used when survey extends over large area or accuracy of
work required is great. In this survey, line connecting any two points on the
earth surface is curved or arc of a great circle.
Classification (Secondary divisions) of Surveys
 Basic Principles in Surveying
1) PRINCIPLE OF WORKING FROM WHOLE TO PART
2) INDEPENDENT CHECK ON MEASUREMENTS
3) REDUNDANCY- LOCATION OF A POINT BY MEASUREMENT FROM AT LEAST TWO
CONTROL POINTS
4) ECONOMY OF ACCURACY AND ITS INFLUENCE ON CHOICE OF EQUIPMENTS
5) CONSISTENCY
6) SAFEGUARDING
7) IMPORTANCE OF SCIENTIFIC HONESTY
 PRINCIPLE OF WORKING FROM WHOLE TO PART
The purpose of working from whole to part is
 to localize the errors and
 to control the accumulation of errors.

In order to localize errors and prevent their accumulation, a set of

control points is always established with great precision first for the
whole area to be surveyed. Later on, details are filled in between
these control points to a relatively smaller precision. If it becomes
necessary to work outside the control framework then it must be
extended to cover the increased area of operations. Failure to do so
will degrade the accuracy of later survey work even if the quality of
survey observations is maintained. Errors which may inevitably arise
are then contained within the framework of the control points and
can be adjusted to it. Thus they have no chance of building up on
accumulating throughout the whole survey.
 PLAN AND MAP
 The main Object of the survey is to develop a plan or a map.
 On a plan or a map only horizontal distances are shown.
 The plan or map is made according to some scale chosen. If the scale is small, the representation is
called map, while it is called plan if the scale is large. Therefore the basic difference between map
and a plan is that of scale.

Mapping Fundamentals
• Since, the actual surface of the earth is curved, and the surface of the map is flat, a method of
projection is usually used to fit a curved surface of earth into a plane surface of paper. However, no
map can represent a terrain without some distortion. To minimize the effect of distortion,
conformal projections are generally employed.
• In case of plane surveying, the earth's surface is regarded as plane and thus, a map is constructed
by orthographic projection. Points are being plotted by their rectangular coordinates, angles and
distances as horizontal.

During the preparation of maps, the factors which need important considerations are:
• • Scales
• • Conventional symbols
• • Generalisation of details
• • Plotting accuracy
• • Rectangular Coordinates
ENTRY INTO SURVEY FIELD BOOKS
BASIC LEVEL MCQs
OLD PSC MCQs

d
1. d, 2. b
 PROBABLE SHORT QUESTIONS
• PRINCIPLES OF SURVEYING
• DIVISION OF SURVEYING
• GEODETIC VS. PLANE SURVEYING
• IMPORTANCE OF SURVEYING TO CIVIL ENGINEERS
 CONTOURING
Contouring in surveying is the determination of elevation of
various points on the land and fixing these points of same
horizontal positions in the contour map.

A line joining points of equal elevations is called a contour line. It

facilitates depiction of the relief of terrain in a two dimensional
plan or map.

Contour Interval: The difference in elevation between successive

contour lines on a given map is fixed. This vertical distance
between any two contour lines in a map is called the contour
interval (C.I.) of the map.

The horizontal distance between two points on two consecutive

contour lines for a given slope is known as horizontal equivalent.
• Contouring: The method of establishing /
plotting contours in a plan or map is known as
contouring. It requires planimetric position of
the points and drawing of contours from
elevations of the plotted points. The field
methods of contouring may be divided into
two classes: direct methods and indirect
methods.
 Characteristics of contour
• The variation of vertical distance between any two contour lines is assumed
to be uniform.
• The horizontal distance between any two contour lines indicates the amount
of slope and varies inversely on the amount of slope. Thus, contours are
spaced equally for uniform slope; closely for steep slope contours and widely
for moderate slope.
The steepest slope of terrain at any point on a contour is represented along the
normal of the contour at that point. They are perpendicular to ridge and valley lines
where they cross such lines.
• Contours deflect uphill at valley lines and
downhill at ridge lines. Contour lines in U-
shape cross a ridge and in V-shape cross a
valley at right angles. The concavity in contour
lines is towards higher ground in the case of
ridge and towards lower ground in the case of
valley.
• Contours do not pass through
permanent structures such as
buildings.

• Contours of different elevations

cannot cross each other (caves
and overhanging cliffs are the
exceptions).

• Contours of different elevations

cannot unite to form one
contour (vertical cliff is an
exception).
 A closed contour line on a map represents either depression or hill. A set of
ring contours with higher values inside, depicts a hill whereas the lower value
inside, depicts a depression (without an outlet).
• Contour lines cannot begin or end on the plan.
• A contour line must close itself but need not be necessarily within the
limits of the map.
• Contours do not have sharp turnings.
METHODS OF LOCATING CONTOUR
• The field methods of contouring may be divided into two
classes: direct methods and indirect methods.
• Direct Method: In the direct method, the contour to be plotted
is actually traced on the ground. Points which happen to fall on
a desired contour are only surveyed, plotted and finally joined
to obtain the particular contour. This method is slow and
tedious and thus used for large scale maps, small contour
interval and at high degree of precision. Direct method of
contouring can be employed using Level and Staff.
• Indirect Methods: In this method, points are located in the
field, generally as corners of well-shaped geometrical figures
such as squares, rectangles, and spot levels are determined.
Elevations of desired contours are interpolated in between spot
levels and contour lines are drawn by joining points of equal
elevation.
 CONTOUR PLOTTING
The choice of suitable contour interval in a map depends upon following
principal considerations:
A) Nature of Terrain:
For flat ground, a small contour interval is chosen whereas for undulating
and broken ground, greater contour interval is adopted. i.e. CI is
inversely proportional to the flatness of the ground.
B) Scale of the Map:
• The contour interval normally varies
inversely to the scale of the map i.e., if the
scale of map is large, the contour interval is
considered to be small and vice versa.
C) Accuracy:
Surveying for detailed design work or for earthwork
calculations demands high accuracy and thus a small
contour interval is used. But in case of location
surveys where the desired accuracy is less, higher
contour interval should be used.

D) Time and fund available:

If the contour interval is small, greater time and funds will
be required in the field survey, in reduction and in
plotting the map. If the time and funds available are
limited, the contour interval may be kept large.
 MCQs on CONTOURING

1- The line joining the points having the

same elevation above the datum surface,
is called a
A. contour surface
B. contour line
C. contour interval
D. contour gradient
2- Contour lines
(a) End abruptly
(b) (b)Cross each other
(c) Are uniformly spaced
(d) Close somewhere
3- Contour lines look to cross each other in
case of
(a) an overhanging cliff
(b) (b) a dam of vertical face
c) a steep hill
d) d) a deep valley
4- The horizontal distance between any two
consecutive contours is called
A. vertical equivalent
B. B. horizontal equivalent
C. contour interval
D. contour gradient
5- When several contours coincide, it indicates
A. a vertical cliff
B. B. a valley
C. C. a ridge
D. D. Plane
6- These V- shaped contours represent fig
a) a ridge
b) a valley
c) An overhanging cliff
d) Nothing
7- In indirect method of contouring, the best
method of interpolation of contours is
A. by graphical method
B. B. by estimation
C. by arithmetical calculation
D. all of these
8- Contour lines cross ridge or valley lines at
A. 30 B. 45 C. 60 D. 90

9- In route surveys, the most suitable method

of contouring is
A. by squares
B. B. by radial lines
C. by cross-sections
D. by tacheometer
10- Which of the following statement is wrong?
A. A series of closed contour lines on the map
indicates a depression if the higher values are
inside
B. A series of closed contour lines on a plane
indicates a hill if the higher values are outside.
C. The uniformly spaced contour lines indicates a
plane surface.
D. all of the above
 ANSWERS- CONTOURING
• 1- b
• 2- d
• 3- a
• 4- b
• 5- a
• 6- d
• 7- c
• 8- d
• 9- c
• 10- d
 Levelling
L4-BAGMATI-CENTER SYLLABUS
3.2.1. Classification of levelling works
3.2.2. Methods of levelling
3.2.3. Levelling instruments and accessories
3.2.4. Principles of levelling
3.2.5. Temporary and permanent adjustments of a
level
3.2.6. Profile levelling
3.2.7. Booking and reducing levels
3.2.8. Errors and its adjustment
L5-BAGMATI-PROVINCE AND LOCAL SYLLABUS

1.2 Levelling
1.2.1 Methods of levelling
1.2.2 Levelling instruments and accessories
1.2.3 Principles of levelling
 Basic Principle of Leveling
• The fundamental principle of leveling lies in
finding out the separation of level lines
passing through a point of known elevation
(B.M.) and that through an unknown point
(whose elevation is required to be
determined).
Definition of Geometry
 Definition of Geometry
• Level line: A line in a level surface (a curved
line)
• Vertical line: A line that follows the direction
of gravity as indicated by a plumb line
• Horizontal line: A line in horizontal plane. In
plane surveying, a line perpendicular to the
vertical
• Level surface: A curved surface that every
point is perpendicular to the local plumb line
(the direction in which gravity acts)
• Horizontal plane: A plane perpendicular to the
direction of gravity. In plane surveying, a plane
perpendicular to the vertical line
• Vertical datum: Any level surface to which
elevations are referred. This is the surface that is
arbitrarily assigned an elevation of zero.
• Elevation: The distance measured along a vertical
line from a vertical datum to a point or an object.
• Geoid: A particular level surface which serves as a
datum for elevations and astronomical
observations.
 Definition of terms
• Differential leveling is the term applied to any
method of measuring directly with a graduated
staff the difference in elevation between two or
more points.

• Precise leveling is a particularly accurate method

of differential leveling which uses highly accurate
levels and with a more rigorous observing
procedure than general engineering leveling. It
aims to achieve high orders of accuracy such as 1
mm per 1 km traverse.
• A level surface is a surface which is everywhere
perpendicular to the direction of the force of gravity.
An example is the surface of a completely still lake. For
ordinary leveling, level surfaces at different elevations
can be considered to be parallel.

• A level datum is an arbitrary level surface to which

elevations are referred. The most common surveying
datum is mean sea-level (MSL).

• An assumed datum, which is established by giving a

benchmark an assumed value (e.g. 100.000 m) to
which all levels in the local area will be reduced. It is
not good practice to assume a level which is close to
the actual MSL value, as it creates potential for
confusion.
• A reduced level (RL) is the vertical distance between a
survey point and the adopted level datum.

• A bench mark (BM) is the term given to a definite,

permanent accessible point of known height above a
datum to which the height of other points can be
referred.
• It is usually a stainless steel pin embedded in a
substantial concrete block cast into the ground. At
hydrological stations rock bolts driven into bedrock or
concrete structures can be used, but structures should
be used warily as they themselves are subject to
settlement. The locations of benchmarks shall be
marked with BM marker posts and/or paint, and
recorded on the Station History Form.
• A set-up refers the position of a level or other instrument at the
time in which a number of observations are made without mooring
the instrument. The first observation is made to the known point
and is termed a back sight; the last observation is to the final point
or the next to be measured on the run, and all other points are
intermediates.

• A run is the leveling between two or more points measured in one

direction only. The outward run is from known to unknown points
and the return run is the check leveling in the opposite direction.

• A close is the difference between the starting level of the initial

point for the outward run and that determined at the end of the
return run. If the levels have been reduced correctly this value
should be the same as the difference between the sum of the rises
and falls and also the difference between the sum of the back sights
and foresights.
• Height of Collimation is the elevation of the optical axis of the
telescope at the time of the setup.
• The line of collimation is the imaginary line at the elevation.
• Turning/Change points:- For leveling over a long
distance, the instrument has to be set up a
number of times. A turning point is the point
selected on the route before shifting the
instrument. These are the points of measurement
which are used to carry the measurements
forward in a run. Each one will be read first as a
foresight, the instrument position is changed, and
then it will be read as a back sight.

• Station:- The station is the point where the staff

is held for taking observation from a leveling
instrument.
• Height of Instrument (H.I.) It is the elevation of the
line of sight ( or a horizontal plane containing the line of
sight) with respect to the datum. It should be noted that
the height of instrument is not the height of the line of
sight above the ground where the leveling instrument is set
up.

• Back Sight (B.S.) It is the reading taken on a staff held at a

point of known elevation or at the point whose elevation
has already been determined. The back sight is usually the
first reading taken after setting up the instrument. The back
sight is taken on a BM for the first setting of the instrument
and on a turning point (T.P.) for the subsequent settings
because the level of turning point can be determined
before the shifting of the instrument.
HI = Known elevation + BS
• Fore sight (F.S.) It is the reading taken on the staff either
held at the last point whose elevation is required or held at
the turning point just before shifting the instrument.
Elevation = HI-FS

 Intermediate Sight (I.S.) It is the reading taken on a staff

held at a point whose elevations is required, but which is
not a turning point or the last point. The intermediate sight
is also known as the intermediate fore sight (I.F.S.). The
intermediate sights are taken at the intermediate stations.
BASIC MCQs
OLD MCQs
BASIC MCQs on “Principle of levelling”
1. When a level is in adjustment, the line of sight
of the instrument is
(a) perpendicular to the vertical axis of the
instrument and parallel to the bubble tube axis.
(b) perpendicular to the vertical axis of the
instrument and bubble level axis.
(c) perpendicular to the bubble tube axis and
parallel to the vertical axis.
(d) none of the above.
2. Change points in levelling are
(a) the instrument stations that are changed
from one position to another.
(b) the staff stations that are changed from
point to point to obtain the reduced levels of
the points.
(c) the staff stations of known elevations.
(d) the staff stations where back sight and fore
sight readings are taken.
3. Reduced level of a point is its height or
depth above or below
(a) the ground surface.
(b) the assumed datum.
(c) assumed horizontal surface.
(d) the line of collimation.
4. A line normal to the plumb line at all points
is known as
A. horizontal line
B. vertical line
C. level line
D. line of collimation
5. An imaginary line tangential to the
longitudinal curve of the bubble tube at its
middle point is called
A. axis of telescope
B. B. axis of level tube
C. level line
D. line of collimation
• Answers:
• 1- a, 2-d, 3-b, 4-c, 5-b
 Determination of reduced level
Whenever any leveling is to be carried out, the first reading is taken on
a point of known elevation. This is called back sight (B.S.) reading.
Before shifting the instrument one reading is taken on a firm object
whose elevation is to be determined. This is known as fore sight
(F.S.) reading.

Between the B.S and F.S numbers of readings known as intermediate

sights (I.S) are taken. All these readings are required to be tabulated
and converted to reduced levels (R.L) for practical use. There are
two systems of working out the reduced levels of points from the
staff readings in the field: (i) the collimation or the height of
instrument (H.I.) and (2) the rise and fall system.
 Height of Instrument (collimation system):
At first, the R.L. of the plane of collimation i.e., height of
instrument (H.I) is calculated for every setting of the
instrument and then R.L. of different stations re calculated
with reference to the height of the instrument. In the first
setting, the H.I. is calculated by adding the B.S. reading
with the R.L. of the bench mark. By subtracting all the
readings of all the intermediate sights and that of the first
change point from the H.I. , then their reduced levels are
calculated. The new H.I is calculated by adding the B.S.
reading with the R.L. of the first change point. The process
is repeated till the entire area is covered.
Arithmetical check: The difference between the sum of back
sights and the sum of fore sights should be equal to the
difference of first and last R.L.
 Rise and fall system:
taken on different stations are compared with the readings taken from the interm
fference in the readings indicates rise or fall depending upon whether the staff re
at of the preceding reading. The rise is added and fall is subtracted from the R.L. o
next station.
k: The difference between the sum of back sights and the sum of fore sights is equ
m of the rise and fall and should be equal to the difference of first and last R.L.
known, the R.L. of B may be found by the following relation:
+ B.S. - F.S.
termediate points may be found by the following relation:
L of B.M + B.S. - I.S
level between A and B is equal to the algebraic sum of these differences or eq
um of back sights and the sum of the foresights (B.S - F.S.). If the difference is p
B is higher than the point A, while if the negative, the point B is lower than the poin
1- A back sight indicates the
A. shifting
B. B. setting up
C. C. height
D. D. angle
2) A staff reading taken on a point whose
elevation is to be determined as on a change
point is called.
A. fore sight reading
B. B. back sight reading
C. C. intermediate sight
D. D. none of these
3) The height of instrument is equal to
A. reduced level of bench mark + back sight
B. B. reduced level of bench mark + fore sight
C. C. reduced level of bench mark +
intermediate sight
D. D. back sight + fore sight
4) The collimation method for obtaining the
reduced levels of points does not provide a
check on
A. fore sights
B. B. back sights
C. C. change points
D. D. intermediate sights
5) The rise and fall method for obtaining the
reduced levels of points provides a check on
A. fore sights only
B. B. back sights only
C. C. intermediate sights only
D. D. all of these
6) Collimation method is used in
A. profile leveling
B. B. differential levelling
C. C. check leveling
D. D.both (a) and (b)
7) Rise and fall method is used in
A. profile leveling
B. B. differential levelling
C. C. check leveling
D. D. none of these
ANSWERS
1- b
2-a
3-a
4- d
5-d
6-a
7-c
Equipment for leveling
 Functions of Salient Parts
Telescope : used to sight a staff placed at desired
station and to read staff reading distinctly.
Diaphragm : holds the cross hairs (fitted with it).
Eye piece : magnifies the image formed in the plane of
the diaphragm and thus to read staff during leveling.
Level Tube : used to make the axis of the telescope
horizontal and thus the line of sight.
Leveling screws : to adjust instrument (level) so that
the line of sight is horizontal for any orientation of
the telescope.
Tripod stand : to fix the instrument (level) at a
convenient height of an observer.
 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°.
 Tilting levels
This type of level is fitted with a circular bubble
for preliminary approximate leveling 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.
 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 leveled
approximately with a circular bubble; the
compensator will then deviate the line of sight by
the amount that the telescope is out of level.
 Digital level
There are fundamentally two types of automatic levels.
First, the optical one whose distinguishing feature is self-
leveling i.e., the instruments gets approximately
leveled by means of a circular spirit level and then it
maintains a horizontal line of sight of its own.
Second, the digital levels whose distinguishing features
are automatic leveling, reading and recording (Figure).
 Staves
The leveling staff is a box section of aluminium or
wood, which will extend to 3 or 5 m in height by
telescoping, hinging or addition of sections. One
face has a graduated scale attached for reading
with the cross-hairs of the level telescope. These
faces can vary in pattern and graduation; 5mm
graduations should be the maximum for accurate
leveling of gauging stations.
 Staff bubbles
These are generally a small circular bubble on an angle
plate which is held against one corner of the staff to
ensure that the staff is held in a vertical position. If the
staff is not held vertical, the reading will be too large
and may be significantly in error.
A staff bubble shall be used at all times. If one is not
available, the "chainman" (staff operator) shall rock the
staff slowly back and forth about the vertical in a line
towards the instrument. The observer notes the
smallest reading which will occur when the staff is
vertical.
8) The telescope of a Dumpy level
(a) Is rigidly fixed to the levelling head
(b) (b) Can be tilted in a vertical plane
(c) (c) Can be taken out of its supports and
reversed
(d) (d)Permits interchange of eye piece and
object glass
 9) The correct position of holding staff is
(a) held vertical
(b) (b) Held vertically and swung to left and right
and the least reading is recorded
(c) (c) Held vertically and swung towards and
away from the person holding and the
highest reading is recorded
(d) (d)Held vertically and swung towards and
away by the person holding it and the least
reading is recorded
10) An invert is taken when the point is
(a) Having high elevation
(b) (b) Above the line of sights
(c) (c) Below the line of sight
(d) (d) Below ground level