1.0 SURVEYING:-
Surveying is a branch of civil engineering.
Surveying is used to represent the general features of land in their proper relative positions.
rom the measurements obtained by surveying, drawings are prepared, which may be in the form of a plan or a map.
Surveying is defined as, "the process of toking measurements on the earth surface to determine the relative positions of different points upon it so that, the points may be represented on a plan or a mop
Surveying deals with the measurements in horizontal plane
1.1 Purpose of surveying:-
1 To determine the relative positions of existing features of the ground.
2. To layout out mark position or proposed structure on ground.
3. To determine areas, volumes and other related quantities.
4. To prepare map of country and detailed locations of cities, towns, villages and major roads.
5. To prepare engineering plan in detail and section of various structures such as roads, railways, bridges,
dams etc.
6. To prepare topographical map showing details of hils, valleys and river
1.2 Type of Surveying:-
Surveying can be classified,
(1) According to Effect of curvature of Earth:
(i) Plane surveying:
In plane surveying, the effect of curvature of earth is not considered. The surface of earth is taken as plane.
The lines connecting any two points are considered as straight lines and the angles of polygon are considered as plane angles.
Plane surveys are carried out for small areas
The degree of accuracy is comparatively low. It involves plain trigonometry.
The extent of surveys up to 260 km' are considered as plane surveys
Plane survey can be carried by any agency concerned.
Uses of plane survey:-
(a) It is basically useful for measurement of areas
(b) It is useful for other purposes, such as engineering, architectural, commercial, scientific geographical exploratory, military, navigational etc.
(c) It can be used for making of plans in connection with legal documents.
(d) It is used for both the location as well as construction of different classes of work. which may include making of plans and the reverse process of working from the plan for setting out works.
(e) It is also useful for other routine works of surveying and levelling.
Engineering Surveying and Levelling
G) Geodetic Surveying:
In geodetic surveying, the curvature of earth is taken into consideration due to large extent of survey for large distances and areas. Geodetic survey involves spherical trigonometry and hence, it is also called as trigonometrical survey. Geodetic surveys are caried out for locating distant control points and for surveying large areas (e.beyond 260 sq.km.). Geodetic surveying is generally performed by Government agencies In India, it is done by Great Trigonometrical Survey (G.T.S) department Geodetic survey is carried out with a high degree of precision or accuracy to obtain data concerning the size and shape of earth.
Uses of Geodetic Surveying:
(a) Accurate maps of wide areas and controls for all ther surveys are obtained by this survey.
(b) Information regarding the positions of points, heights above sea-level, true bearings etc is provided by
this survey.
(c)It is useful for obtaining the most useful checks at various stages for survey work carried out by an engineer or a surveyor.
(d) t enables local surveys to be laid down and plotted on the official printed maps and plans.
(e) in case of dispute of property, certain plans may be used as legal documents.
(2) According to Nature of Field:-
Labeling Surveying: It includes,
•Topographical surveys to determine the natural of country, such as rivers, lakes, hills etc. and artificial features, such as, roads, railway, canals, towns and villages.
•Cadastral surveys to determine additional details, such as, boundaries of fields, houses and other properties. For this, cadastral surveys are plotted on larger scale than topographical surveys.
•Engineering surveys to determine quantities or to collect data for designing of engineering works, such as, roads, reservoirs, water supply system, sewage disposal systems etc. This can be also called as City Surveys.
(ii) Astronomical Surveying:-
• To determine the absolute location of any point or the absolute location and direction of any line on the surface of earth.
(iii) Marine Survey or Hydrographic Survey:-
•It deals with bodies of water for purpose of navigation, water supply etc.
•It is also called as hydrographic survey.
3.According to Instruments or Methods Employed
(i) Theodolite survey
(ii) Chain survey
(iii) Triangulation survey
(iv) Traverse survey
(v)Techometric survey
(vi) photographic survey
(vii) Aerial survey
(viii) Photographic survey
(4) According to object surveying
(i) Geological survey
(ii) Engineering survey
(iii) Archaeological survey
(iv) Military survey
(v) Mine survey
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