surveying
Surveying
♣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.
♣ It involves the measurement and recording of the size
and shape (including the vertical shape) of an area on the
earth's surface.
(a) Field work- taking measurements
(b)Office work- computing and drawing
The process of survey divided into two parts:
Object of survey
♣The primary object of survey is the preparation of plan
or map.
♣The results of surveys when plotted and drawn on paper
constitute a plan.
♣The representation is called a map, if the scale is small.
If the scale is large, it is called a plan.
Primary division of surveying
Surveying may be divided into two general
classes:
(a) Geodetic surveying
(b)Plane surveyingGeodetic surveying is also called trigonometrical surveying . In this survey, the
curvature of the earth is taken into account, since large distances and areas are
covered.
In plane 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.
CLASSIFICATIONS
I. Classification based upon the nature of the field of survey:
(a) Land Surveys.
(b) Marine or Navigation Surveys.
(c) Astronomical Surveys.
II. Classification 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.
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.
Uses of survey:
The planning of all engineering and construction
projects extending over large areas, such as highways,
railways, irrigation, water supply etc., are based upon
elaborate and complete surveys.
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