Basic Concepts of Surveying Principles of surveying purpose of surveying uses of surveying

1. Prepared by
Prof. Janki Patel
INTRODUCTION

2. Surveying and levelling
■ Surveying is the art of determining the relative positions of points on, above or
beneath the surface of the earth. The relative positions are determined by
measuring horizontal distances, vertical distances (elevations), horizontal
angles and vertical angles accurately using various surveying instruments.
■ Levelling is a branch of surveying dealing with determination of relative heights of
the point on the surface of the earth in vertical plane.
■ Surveying deals with measurements in a horizontal plane.
■ Levelling deals with measurements in a vertical plane.

3. Surveying and levelling

4. Purpose of surveying
■ To take measurements to determine the relative positions of the points on
above or beneath the surface of the earth.
■ To determine areas and volumes.
■ To layout or to mark the positions of the proposed structures on the ground
e.g. building, canal, road, etc.
■ To prepare a map or plan to show the relative positions of the objects on the
surface of the earth.
■ To fix the boundaries of districts, states and countries.

5. Uses of surveying
■ To prepare a topographical map which shows natural features of a country
such as rivers, streams, lakes, hills, valleys forests etc.
■ To prepare a cadastral map which shows the boundaries of fields, plots etc.
■ To prepare contour map to know the topography of the area to find out the
best possible site for dam, canals, buildings, roads, railways, bridges etc.
■ Route surveys are conducted to fix the alignment of road, railway, canal,
electrical tower line, tunnel, bridge etc. on the ground.

6. Uses of surveying
■ To plot irregular boundaries of lots and existing structures on paper.
■ To lay particular gradient or slope for water supply, drainage, gas line or
road.
■ To carry out survey on lakes, rivers and sea to study the bed profile.
■ Finding out level difference between various points on the ground surface.
■ Military survey is used for determining points of strategic importance.
■ Mine survey is used for the exploring mineral wealth.
■ City survey is used for planning streets, water supply systems, sewers etc.
■ Remote sensing is useful to determine agricultural soil, forest cover, water
bodies etc.

8. Principles of surveying
■ To work from whole to part
■ To fix positions of new points by at least two independent processes.

9. To Work From Whole To Part
According to this principle, it is always
desirable to carryout survey work 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.

10. To fix positions of new points by at
least two independent processes.
■ According to this principle, the relative position of a point to be surveyed
should be located by measurement from at least two points of reference,
the positions of which have already been fixed.
■ If P and Q are the two reference points on the ground, any other point, such as
R, can be located by any of the direct methods shown in the above figures.
But, although a single method is sufficient to locate the relative position of ‘R’
with respect to reference points P and Q, it is necessary to adopt at least any
two methods to fix the position of point ‘R’.

12. a) Distances PR and QR are measured.
b) Angle QSR is a right angle and distances QS and SR are measured.
c) Angle PQR and distance QR are measured.
d) Angle PQR and distance QPR are measured.
e) Angle PQR and distance PR are measured.

13. Method of Surveying in Civil
Engineering
■ Primary types of Surveying are:
■ Plane surveying
■ Geodetic surveying

14. Plane surveying
■ Plane surveying is conducted by state agencies as well as private agencies.
■ As we know earth is spherical in shape but its diameter is big enough to
consider plane in small dimensions.
■ It is that type of surveying in which the mean surface of the earth is
considered as a plane and the spheroidal shape is neglected.
■ All triangles formed by survey lines are considered as plane triangles.
■ Plane surveying is done of the area of survey is less than 250 km2.

16. Geodetic surveying
■ Geodetic survey is conducted by survey department of the country.
■ It is that type of surveying in which the curved shape of the earth is taken in
to account.
■ The object of geodetic survey is to determine the precise position on the
surface of the earth, of a system of widely distant points which form control
stations in which surveys of less precision may be referred. .
■ Line joining two points is considered as curved line and angles are assumed
as spherical angles.
■ It is carried out if the area exceeds over 250 km2.

17. Classification of surveys
■ Based on the nature of field of survey.
■ Based upon object of survey.
■ Based upon instrument used.
■ Based upon the method employed,

18. Based upon the nature of the field
■ Land Surveying – Conducted on the earth’s surface/land.
■ Marine Surveying – Conducted on water bodies like ocean,
rivers etc.
■ Astronomical Surveying – Conducted to study the position
and movement of cadastral bodies.

19. Based upon the object of survey
■ Archeological surveys
■ Geotechnical and geographical surveys
■ Mine surveys
■ Military surveys
■ Control surveys
■ Topographical surveys
■ Cadastral surveys
■ Route surveys
■ Engineering surveys
■ Construction surveys

20. Based upon the object of survey
■ Archeological surveys – Conducted for unearthing relics of antiquity.
■ Geotechnical and geographical surveys – Conducted for determining the
different strata in the earth’s crust.
■ Mine surveys – Conducted for exploring mineral wealth and to guide mining
operations.
■ Military surveys – Conducted for military purpose.
■ Control surveys – Conducted for establishing a network of control points which
serve as reference frame work.

21. Based upon the object of survey
■ Topographical surveys – Conducted to determine the nature of features of
hills, river, lakes, towns, villages, buildings, roads, railways etc.
■ Cadastral surveys – Conducted to determine the details of boundaries of fields,
houses and other private and public properties.
■ Route surveys – Conducted to determine the alignment of highway, railway,
canal, pipelines, transmission line etc.
■ Engineering surveys – Conducted for collecting data for engineering purposes
like design of dam, road, bridges etc.
■ Construction surveys – Conducted for location of construction works, giving
line, fixing grades etc.

22. Based upon instrument used
■ Chain surveys – Chain or tape is used for linear distance measurement.
■ Compass surveys – Compass is used for measurement of horizontal angles.
■ Plane table surveys – Plane table is used for preparing plan of given area and
collecting details.
■ Theodolite surveys – Theodolite is used for measuring vertical and horizontal
angles.
■ Tachometric surveys – Tachometer is used for measuring horizontal and vertical
distance.

23. Based upon instrument used
■ Photographic and aerial surveys – Photographs taken from higher altitude are
used for collecting the details of earth’s features.
■ Electronic distance measurement surveys – Device working on the principle of
electronic distance measurements is used for determining the distance
between two inter-visible objects.
■ Remote sensing – Data collected from satellites are used for determining the
positions of earth’s features.

24. Based upon the method employed
■ Triangulation surveys – The area is covered with a network of triangles and
details are collected.
■ Traverse surveys – The area is covered by a series of survey lines forming
traverse and details are collected.

25. THANK YOU
PREPARED BY
- PROF. JANKI PATEL