Surveying 2

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Prepared by R.Vijayakumar, B.Tech (CIVIL), CCET, Puducherry
SURVEYING – II
UNIT – I
1. What is Satellite Station?
A Subsidiary Station is established as near the true or principal station
as possible, the station so established is called a satellite station or eccentric
station or false station.
2. What is working from whole to part?
This means, when an area is to be surveyed, first a system of control
points is to be established covering the whole area with very high precision.
Then minor details are located by less precise methods. The idea of working
this way is to prevent the accumulation of errors and to control and localize
minor errors which, otherwise, would expand to greater magnitudes if the
reverse process is followed, thus making the work uncontrolled at the end.
3. What are the applications of triangulation?
 Optical 3d measuring systems use this principle as well in order to
determine the spatial dimensions and the geometry of an item.
(Basically, the configuration consists of two sensors observing the
item. One of the sensors is typically a digital camera device, and the
other one can also be a camera or a light projector. The projection
centers of the sensors and the considered point on the object’s surface
define a (spatial triangle).
 Within this triangle, the distance between the sensors is the base b and
must be known. By determining the angles between the projection

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rays of the sensors and the basis, the intersection point, and thus the
3d coordinate, is calculated from the triangular relations.
4. List the requirements in selecting a site as a baseline.
 The site should be fairly level. If, however, the ground is sloping, the
slope should be uniform and gentle. Undulating ground should, if
possible be avoided.
 The site should be free from obstructions throughout the whole of the
length. The line clearing should be cheap in both labour and
compensation.
 The extremities of the base should be intervisible at ground level.
 The ground should be reasonably firm and smooth. Water gaps
should be few, and if possible not wider than the length of the long
wire or tape.
 The site should suit extension to primary triangulation. This is an
important factor since the error in extension is likely to exceed the
error in measurement.
5. What is meant by the strength of figure of a triangulation system?
The strength of figure is a factor to be considered in establishing a
triangulation system to maintain the computations within a desired degree of
precision. It plays also an important role in deciding the layout of a
triangulation system. It is based on the fact that computations in
triangulation involve use of angles of triangle and length of one known side.
The other two sides are computed by sine law.

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6. State the objectives of Triangulation survey?
 To establish accurate control for plane and geodetic surveys of large
areas, by terrestrial methods.
 To establish accurate control for photogrammetric surveys of large
areas,
 To assist in the determination of the size and shape of the earth by
making observations for latitude, longitude and gravity, and
 To determine accurate locations of points in engineering works such
as piers and abutments of long span bridges, fixing centre line,
terminal points and shafts for long tunnels, measurement of the
deformation of dams, etc.
7. Write some of the modern surveying equipments.
Total station is a theodolite with an Electronic Distance Measurement
Device. Total station has also been one of the reasons behind the drastic
change of technology in the surveying field. EDMD shifted the surveying
technology from optical mechanical devices to digital electronic devices. In
spite of just being distance measuring equipment, total station can also be
used for leveling when adjusted in a horizontal plane. Most of the ultra-
modern surveying devices are a combination of one or more of these
devices.
8. Define bench marking.
Bench mark is a relatively permanent point of reference whose
elevation with respect to some assumed datum is known. It is used either as
a starting point for leveling or as a point upon which to close as a check.

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9. What is meant by Trignometrical leveling?
Trignometrical leveling is the process of determining the differences
of elevation of the given station from observed vertical angles and known
distance.
10.Define Signals.
A signal is a device erected to define the exact position of an observed
station. It may be classified as,
 Daylight or Non luminous (opaque) signal
 Sun or luminous signal
 Night signal
UNIT – II
1. What are the functions of reverse curve?
Reverse curves are useful when laying out such things as pipelines,
flumes, and levees. The surveyor may also use them on low-speed roads and
railroads. They cannot be used on high-speed roads or railroads since they
cannot be properly super elevated at the PRC. They are sometimes used on
canals, but only with extreme caution, since they make the canal difficult to
navigate and contribute to erosion.
2. How curves are designated?
A curve may be designated either by the radius or by the angle
subtended at the centre by a chord of particular length. In India, a curve is
designated by the angle (in degrees) subtended at the centre by a chord of 30
metres (100 ft.) length. This angle is called the degree of curve (D). The
degree of the curve indicates the sharpness of the curve.

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3. Define vertical curve.
Vertical curves are equal-tangent curves, which mean that the
horizontal distance from the center of the curve to the end of the curve is
identical in both directions. Unequal-tangent vertical curves, which are
simply equal-tangent curves that have been attached to one another, are used
only infrequently.
4. Write the methods of setting out a circular curve.
 Linear methods
 By ordinates or offsets from long chord
 By successive bisection of arcs
 By offsets from the tangents
 By deflection distances
 Angular method
 Rankine’s method of tangential angle
 Two theodolite method
 Tacheometric method
5. What is transition curve?
A curve of constantly changing radius, used to connect a circular arc
to a straight line or to an arc of different curvature.
6. What is sag or valley curves?
Valley curve or sag curves are vertical curves with convexity
downwards. They are formed when two gradients meet in any of the
following four ways:

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 When a descending gradient meets another descending gradient
 When a descending gradient meets a flat gradient
 When a descending gradient meets an ascending gradient
 When an ascending gradient meets another ascending gradient
7. Why the reverse curve is not provided in high speed ways?
According to the laws of mechanics, when a vehicle travels on a curve
it is forced outward by centrifugal force. It is impractical to balance
centrifugal force by super elevation alone, because for any given curve
radius a certain super elevation rate is exactly correct for only one driving
speed. Hence we cannot provide reverse curve in high speed ways.
8. List the various types of curve.
 Simple curve
 Compound curve
 Reverse curve
 Transition curve
 Vertical curve
9. What are the functions of a transition curve?
Primary functions of a transition curves (or easement curves) are:
 To accomplish gradual transition from the straight to circular curve,
so that curvature changes from zero to a finite value
 To provide a medium for gradual introduction or change of required
super elevation
 To changing curvature in compound and reverse curve cases, so that
gradual change of curvature introduced from curve to curve

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10.What are the uses of vertical Curves?
 Allow smooth transition from one grade to another (driver comfort)
 Provide adequate sight distance at junction of grades and for
overtaking (safety)
 Provide satisfactory appearance (aesthetics)
UNIT – III
1. What are accidental errors?
Accidental errors are those which remain after mistakes and
systematic errors have been eliminated and are caused by a combination of
reasons beyond the ability of the observer to control. They tend sometimes
in one direction and some times in the other, (i.e.) they are equally likely to
make the apparent result too large or too small.
2. What is well conditioned triangle?
The triangles having internal angles between 30o
& 130o
are known as
well conditioned triangle. In other words, the shape of the triangle should be
such that any error in the measurement of angle shall have a minimum effect
upon the lengths of the calculated side. Such a triangle is then called well -
conditioned triangle.
3. Define photogram metric.
Photogram metric surveying or Photogrammetry is the science and art
of obtaining accurate measurements by use of photographs, for various
purposes such as the construction of planimetric and topographic maps,
classification of soils, interpretation of geology, acquisition of military

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intelligence and the preparation of composite pictures of the ground. The
photographs are taken either from the air or from station on the ground.
4. What is meant by method of equal shifts?
The method of equal shifts indicates that any shift which is necessary
to satisfy the local equation should be the same for each triangle of the
polygon. Similarly, any shift necessary to satisfy the side equation should
be the same for each triangle.
5. What is the use of correlates?
Correlation is a statistic that measures the linear relationship between
two variables. This explanation is intended to help the layperson understand
the basic concept of correlation without requiring a lot of technical
knowledge. We use correlation to help understand what drives employee
satisfaction or employee engagement within organizations. The same
technique can also be used for customer satisfaction or other types of
surveys as well.
6. Define normal equations.
A normal equation is the one which is formed by multiplying each
equation by the coefficient of the unknown whose normal equation is to be
found and by adding the equation thus formed. As the number of normal
equations is the same as the number of unknowns, the most probable values
of the unknown can be found from these equations.

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7. What are the triangulation adjustments?
 Single angle adjustment
 Station adjustment
 Figure adjustment
8. Define Residual error.
A residual error is the difference between the most probable value of a
quantity and its observed value.
Residual error = Most probable value – Observed value
9. Write the types of error measurements.
 Mistakes or Gross error
 Systematic or Cumulative error
 Accidental or Random error
10.What are systematic errors?
A systematic error is an error that under the same conditions will
always be of the same size and sign. A systematic error always follows
some definite mathematical or physical law, and a correction can be
determined and applied. Such errors are of constant character and are
regarded as positive or negative according as they make the result too great
or too small. Their effect is therefore, cumulative.
11.What is the principle of least square?
According to the principle of least square, the most probable value of
an observed quantity available from a given set of observations is the one for
which the sum of the squares of errors is a minimum.

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12.Define most probable value.
The most probable value of a quantity is the one which has more
chances of being true than has any other. It is deduced from the several
measurements on which it is based.
13.What are Mistakes or Gross errors?
Depends upon the observer, a mistake cannot be corrected unless the
observer get training. The mistakes are errors that arise from inattention,
inexperience, carelessness and poor judgment of confusion in the mind of
the observer.
14.Distinguish between true value and most probable value.
S.NO TRUE VALUE MOST PROBABLE VALUE
1. The true value of a quantity is
the value which is absolutely
free from all the errors.
The most probable value of a
quantity is the one which has
more chances of being true than
has any other.
2. The true value of a quantity is
indeterminate since the true
error is never known.
It is deduced from the several
measurements on which it is
based.

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UNIT – IV
1. What are the uses of Tellurometer?
 The instrument is highly portable.
 Observations can be taken both during day as well as night, while in
the geodimeter; observations are normally restricted in the night.
2. List out apparatus for making sounding.
 Sounding boat
 Sounding rods or poles
 Lead lines
 Sounding machine
 Fathometer
3. What is the use of Electromagnetic Distance Measurement?
The term EDM is used to describe a category of instruments that
measure distance using an electronic signal. The instrument broadcasts a
focused signal that is returned by a prism or reflection from the object.
4. What do you meant by carrier wave?
A carrier signal, carrier wave or just carrier is the electromagnetic
wave that can be modulated, as in frequency, amplitude or phase, to transmit
speech, music, images or other signals. A wave form (usually sinusoidal)
that is modulated (modified) with an input signal for the purpose of
conveying information. This carrier wave is usually a much higher
frequency than the input signal. The purpose of the carrier wave is usually
either to transmit the information through space as an electromagnetic wave
(as in radio communication), or to allow several carriers at different

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frequencies to share a common physical transmission medium by frequency
division multiplexing.
5. Write the uses of electro optical instruments.
Electro-optical EDMs use the velocity of light waves to determine
the distance between two points. Electro-optical systems are available for a
wide range of applications including night vision systems, medical & laser
surgical instruments, industrial lasers for marking, cutting & welding,
optical information storage systems, imaging systems for satellites, camera,
telescopes & microscopes, laser imaging systems & laser range-finding &
target designator systems for the military.
6. Define electromagnetic waves.
Electromagnetic waves are waves that contain an electric field and a
magnetic field and carry energy. They travel at the speed of light.
Electromagnetic waves, though extremely complex in nature, can be
represented in the form of periodic sinusoidal waves.
7. What are the sources of error?
The errors may be classified as,
 Instrumental errors
 Personal errors
 Errors due to natural causes
8. Define control segments.
Control segment is the vital link in GPS technology. The Control
Segment consists of facilities required for satellite health monitoring,

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telemetry, tracking, command and control, ephemeris computations and up
linking. Control segment functions, providing command and control of the
GPS constellation.
UNIT – V
1. What are the advantages of fathometer?
 It is more sensitive than the lead line
 The speed of sounding and plotting is increased
 It can be used when a strong current is running and when the weather
is unsuitable for the soundings to be taken with the lead line
 A record of the depth is plotted immediately and provides a
continuous record of the bottom as the vessel moves forward
 The error due to estimation of water level in a choppy sea is reduced
owing to the instability of the boat
2. Define the term remote sensing.
Remote sensing is broadly defined as science and art of collecting
information about objects, area or phenomena from distance without being
in physical contact with them.
3. What are the basic principles of remote sensing?
Every object on the earth emits its own internal energy according to
its molecular and atomic structure, in addition to reflecting sun light during
the day time. The radiations can be registered by sensors in several
wavelengths, including those in the infrared and microwave regions of the
spectrum. When such sensors are installed on aircrafts or on satellites they
can record the earth’s objects from for off distances. Such distant

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acquisition of information about the objects on the earth’s surface is known
as remote sensing.
4. List the types of EDM instruments.
 Microwave instruments
 Visible light instruments
 Infrared instruments
5. What are the applications of fathometer?
 It is used for ocean sounding where the depth of water is too much,
and to make a continuous and accurate record of the depth of water
below the boat or ship at which it is installed.
 It is adjusted to read depth in accordance with the velocity of sound in
the type of water in which it is being used.
6. Define GPS?
The Global Positioning System (GPS) is a space-based satellite
navigation system that provides location and time information in all weather
conditions, anywhere on or near the earth where there is an unobstructed line
of sight to four or more GPS satellites.
7. Define GIS?
The modern computers can process maps and data with suitable
computer programmer. The process of integrating and analyzing various
types of data with the help of computer is known as Geographic Information
System.

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8. Define spatial data and non – spatial data.
SPATIAL DATA: Any data which are directly or indirectly referenced to a
location on the surface of the earth are spatial data. Also known as
geospatial data or geographic information it is the data or information that
identifies the geographic location of features and boundaries on Earth, such
as natural or constructed features, oceans, and more. Spatial data is usually
stored as coordinates and topology, and is data that can be mapped.
NON-SPATIAL DATA: Data that relate to specific precisely defined
location. The data are often statistical but may be text, images or
multimedia. These are linked in the GIS to spatial data that defines the
location.
9. What are the uses of Total station?
 Angle measurement
 Distance measurement
 Coordinate measurement
 Data processing
 Mechanical and Electrical Construction
 Mining
10.What are the characteristics of different platforms?
Platforms refer to the structures or vehicles on which remote sensing
instruments are mounted. The platform on which a particular sensor is
housed determines a number of attributes, which may dictate the use of
particular sensors. These attributes include: distance the sensor is from the
object of interest, periodicity of image acquisition, timing of image

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acquisition, and location and extent of coverage. There are three broad
categories of remote sensing platforms: ground based, airborne, and satellite.
11.What are the basic principles of data processing?
It is the activity to convert data in to information. The three activities
in data processing are capturing data (Input), manipulating data (Process)
and outputting the result (Output). It is classified in to two, Manual Data
Processing (MDP) and Electronic Data Processing (EDP).

Surveying 2

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