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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