Engr. Shams Ul Islam is an assistant professor in the Civil Engineering Department at CECOS University Peshawar. He has a Ph.D. in structural engineering in progress from CECOS University, an M.S. in structural engineering from CECOS University, and a B.S. in civil engineering from UET Peshawar. He has teaching experience at several universities and his office is located in front of the main library at CECOS University. The document then provides an overview of surveying, including definitions, primary divisions of surveying into geodetic and plane surveying, classifications based on nature, object, and instruments used, as well as measurements, principles, operations, errors, and accuracy
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introduction of surveying
1. ENGR. SHAMS UL ISLAM
ASSISTANT PROFESSOR
CIVIL ENGINEERING DEPARTMENT
CECOS UNIVERSITY PESHAWAR
2. BRIEF INTRODUCTION
• Ph.D. (Structural Engineering in Progress) from CECOS
University Peshawar
• M.S (Structural Engineering) from CECOS University Pesh.
• B.S (Civil ) from UET Peshawar (Bannu)
• Teaching Experience in GCT Peshawar , GCT Nowshera
and CECOS University Peshawar
• Office located in from of Main Library CECOS Uni.
4. Surveying
Surveying is defined as “the science, art, and technology of
determining the relative positions of points above, on, or
beneath the Earth’s surface, or of establishing such points. OR It
is the art of determination of horizontal distances, differences in
elevation, directions, angles, locations, areas and volumes on or
near the surface of the earth.
4Engr.Shams Ul Islam (shams@cecos.edu.pk)
5. Primary Division of Surveying
Surveying may be divided into two general classes
Geodetic surveying
Plane surveying
5Engr.Shams Ul Islam (shams@cecos.edu.pk)
6. Geodetic Surveying
It is also called Trigonometrical surveying. The object of a
geodetic surveying is to determine the precise positions on the
surface of the earth of a system of widely distant points and the
dimensions of areas. In this survey, the curvature of the earth is
taken into account, since large distances and areas are covered.
6Engr.Shams Ul Islam (shams@cecos.edu.pk)
7. Plane Surveying
In this survey, the earth’s surface is considered as a plane. The
curvature of the earth is not taken into account, as the surveys
extend only to small areas. The line joining any two points as a
straight line and all angles are plane angles. Surveys normally
carried out for the location and construction of roads, canals
and, buildings. In general, the surveys necessary for the works
of man are plane surveys.
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8. Classification
Surveys may be classified in a variety of ways.
I. Classification based upon the nature of the field of survey:
(a) Land Surveys.
(b) Marine or Navigation Surveys.
(c) Astronomical Surveys.
II. Classification based upon the object of survey:
(i) Archaeological surveys.
(ii) Geological Surveys -for determining different strata in the earth’s crust.
(iii) Mine Surveys- for exploring mineral wealth such as gold, coal, etc.
(iv) Military Surveys- for determining points of strategic importance both offensive
and defensive.
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9. Continue…
III. Classification based upon the methods employed in survey:
(a) Triangulation Surveys.
(b) Traverse Surveys.
IV. Classification based upon the instrument employed:
(i) Chain Surveys.
(ii) Theodolite Surveys.
(iii) Tacheometric Surveys.
(iv) Compass Surveys.
(v) Plane Table Surveys.
(vi) Photographic and Aerial Surveys
9Engr.Shams Ul Islam (shams@cecos.edu.pk)
10. Measurements
There are two kinds of measurements used in plane surveying
Linear
Angular
The linear measurement may be further subdivided into:
Horizontal distances
Vertical distances
The Angular measurements may be further subdivided into:
Horizontal angle
Vertical angle.
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11. Principles of Surveying
The fundamental principles upon which the surveying is being
carried out are
1. Working from whole to part.
2. After deciding the position of any point, its reference must
be kept from at least two permanent objects or stations
whose position have already been well defined.
The purpose of working from whole to part is
• To localize the errors and
• To control the accumulation of errors.
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12. Operation in Surveying
Different operations performed in surveying are:
1. Planning
2. Field Observation
3. Office Works
4. Setting out Works
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1. Planning
Planning is performed to decide
• The methods to be adopted for surveying;
• The resources (instruments & personnel) to be used;
• The control points / stations to be used
The planning operation needs a-priori field visit and this is
known as reconnaissance.
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2. Field Observations
Field observations involves
• Collection of field data by making necessary measurements,
• Recording of observed data in a systematic manner.
Before starting any field observation, the permanent adjustments
of all the instruments need to be checked thoroughly by trained
personnel and if required, it must be adjusted.
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3. Office Work
It involves
• Processing, analyzing and calculation of observed data,
• Preparation of necessary data,
• Making of a plan or map of the area,
• Computation of relevant field parameters as per design for
setting out engineering works at site.
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4. Setting out work
To locate and establish different parameters / dimensions at the site
as per design for further engineering works or for the construction
purposes.
16Engr.Shams Ul Islam (shams@cecos.edu.pk)
17. Error in Measurements
Surveying is based on measurements and whenever we take measurements,
say of a length or of an angle, we make errors. These errors are due to
(i) Natural causes (ii) Instrumental imperfections and (iii) Personal
Limitations.
Examples of natural causes are variation in speed of wind, temperature and
magnetic declination. A tape or chain which is normally of 30 m length does
not remain so if the temperature changes and as a result error in the
measurement of length occurs. However sophisticated an instrument may be,
it is never perfect. Finally there are limitations of the human senses of sight
and touch. However much we , may try it is difficult to bisect exactly a rod
while taking measurements of an angle.
17Engr.Shams Ul Islam (shams@cecos.edu.pk)
18. Types of Errors
Very broadly errors are of two types;
1. Systematic or cumulative.
2. Accidental, random or compensating.
Systematic errors can always be corrected because their magnitude
and sign can both be determined. For example. if a chain is of
standard length under a particular pull and temperature and if the
pull or temperature changes. we can compute its effect on the
length of the chain. i.e. whether it will increase or decrease and by
how much and then apply suitable corrections.
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19. Systematic or cumulative.
Systematic errors can always be corrected because their
magnitude and sign can both be determined. For example. if
a chain is of standard length under a particular pull and
temperature and if the pull or temperature changes. we can
compute its effect on the length of the chain. i.e. whether it
will increase or decrease and by how much and then apply
suitable corrections.
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20. Accidental, random or compensating
Accidental. random or compensating errors are subject to chance
and hence follow the laws of probability. The magnitude and sign
of errors are not definitely known. They are sometimes positive.
sometimes negative, sometimes of small magnitude. sometimes of
large magnitude and hence cannot be computed or eliminated.
However, by taking a large number of observations we can make
an estimate of magnitude of the error likely to be involved.
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21. Accuracy and Precision of Measurements
Accuracy refers to how close a measurement is to the true
value where as Precision is how consistent results are when
measurements are repeated. Precise values differ from each
other because of random error, which is a form of
observational error.
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