FUNDAMENTALS OF SURVEYING

They are 4 types of surveying:

• geodetic survey
• topographical survey
• hydrographical survey
• plane survey

Hydrographical survey
This type of survey deals with water bodies like
streams, lakes etc.
It is also called as bathymetric surveying which is
done to identify physical features present
underwater.
It is the science of measuring all factors beneath
water that affect all the marine activities like
dredging, marine constructions, offshore drilling etc.
It is mainly carry out by sensors, sounding or
electronic sensor system for shallow water.
This survey takes part in necessary data collection
relating to construction and developments of port
facilities, such as pier construction, breakwater
construction etc.
Topographical survey
This type of survey is conducted d to locate natural
and artificial features present on the earth Surface.
Artificial features are building,
monuments etc while
atural features means hills. rivers etc.

with
low estimate the exact quantities and cost of project,
the choice of the best option/location for the project.
It is done to collect precise information required for
to identify all issues in the project development process.
of field work and gathering data from a veriety of sources
Preliminary surveying: A preliminary survey consists
Survey upto 195.5 km² in area.
of earth is regarded as plane surface. It is adopted for
Plane surveying: It this type of surveying, mean surface
Note:
km²).
plane surveying generally adopted for lager area (>195.5
of earth is taken into account. It is more accurate than
Geodetic surveying: In this type of surveying curvature
water bodies like streams, lakes etc.

1. Land surveying
   Topographical surveys: This consists of horizortal
   and vertical location of certain points by linear and
   angular measurements and is made to determine
   the natural features of a country such as diverse,
   streams, lakes, woods, hils etc. and such artificial
   features as roads, railways, canals, towns and
   villages.
   Cadastral survey: Cadastral survey are nade
   incident to the fixing of property lines, the
   calculation of land area. They are also made to fix
   the bourndaries of municipalities and of state and
   City survey: They are made in connection with
   the construction of streets water supply systerm,
   sewers and other works.
2. Marine or hydrographic survey
   Marine or hydrographic survey deals with bodies of
   water for purpose of navigation, water supply.
   harbour works or for the determination of mean
   sea level.
   The work consists in measurement of discharge of
   streams, making topographic survey of shores and
   banks, taking and locating sounding to determine
   the depth of water and observing the fluctuations
   of the ocean tide.
3. Astronomical survey
   The astronomical survey offers the Surveyor means
   of determining the absolute location of any point or
   the absolute location and direction of any line on
   the surface of the earth. This consist an observations
   to the heavenly bodies such as the sun or any
   fixed star.
   federal jurisdictions.

The magnetic needle when suspended freely takes
up a position parallel to earth magnetic line. Its
horizontal projection defines the magnetic meridian
and exhibit the direction magnetic North and South.
At elevation, the lines of magnetic earth are inclined
downwards towards north in Northern hemisphere
and vice-versa.
So magnetic needle in equilibrium is not in a
horizontal plane but at a plane inclined at definite
angle to the horizontal. This angle is known as
dip.
The angle of dip is 0° at equator and 90° at
magnetic poles.
A small sliding sleeve weight is attached to one
end of magnetic needle.
Lines joining the place of same dip are known
as isoclinic lines.
Lines joining the place of zero dip are aclinic
lines.

Obstacles in Chaining :
When chaining a survey line, sometimes various
obstacles are encountered in the field. These
obstacles are of various types.
Some obstacles are such that chaining round the
obstacle is possible, such as a small pond, a
small bend in the river, etc. While in other cases,
the chaining round the obstacle is not possible, for
example a long river across the survey line.
Depending upon the type of obstacies, a suitable
method has to be take
Obstacles in Ranging :
Sometimes, there are obstacles, such as a forest
or a hill, on survey lines which obstruct ranging as
both end stations of the line are not intervisible.
Then the method used in ranging out past these
obstructions will depend upon whether both ends
are visible from some other (intermediate) points
or not.
If both ends are visible from some intermediate
point, reciprocal ranging may be use. However, if
both the end stations are not visible from an
intermediate point, the method of the random line,
shall be use.

Cloth or Linen tape: This is closely woven linen
or synthetic material and is varnish to resist the
moisture and are available in lengths of 10-30 m
and widths of 12-15 mm.
Disadvantages of cloth or linen tape is
length get changes by stretching.
Metallic tape : This is a linen tape with brass or
Copper wires woven into it longitudinally to reduce
stretching. The wires are not visible because it is
varnished.
Steel tape : They are made up of steel or stainless
steel strips. These are available in lengths of 1-50
m and width of 6-10 mm. Steel tapes cannot be
used in ground with vegetation and weeds.
Invar Tape : These are made up of an alloy of
nickle (36%) and steel (64%). These tapes have
very low coefficient of thermal expansion (0.122 x
10-6/°C). These are available in lengths of 30, 50
and 100 m and width of 6 mm.
Advantages of invar tape is that it is highly precise
and less affected by temperature changes in
comparison to the other tapes.

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