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R.T.U / G.I.T Jaipur SUBJECT –Surveying (3CE4-05) CIVIL ENGG./ III SEM UNIT –2 Levelling 1 PRATEEK SHARMA R.T.U / G.I.T Jaipur SUBJECT –Surveying (3CE4-05) CIVIL ENGG./ III SEM • Blown up Detail:- 1.1 Definition of Levelling 1.2 Levelling Terms 1.3 Types of levelling 1.4 Reduced Level Calculation 1.5 Curvature correction(Cc) 1.6 Distance of visible horizon 1.7 Levelling Instrument 1.8 Errors in Levelling 1.9 Contours and contour lines 1.10 Methods of Contouring 1.11 Area and volume measurements 2 PRATEEK SHARMA R.T.U / G.I.T Jaipur Surveying (3CE4-05) CIVIL ENGG./ III SEM 1.1 Definition of Levelling • Levelling or leveling is a branch of surveying, the object of which is to establish or verify or measure the height of specified points relative to a datum. • It is widely used in cartography to measure geodetic height, and in construction to measure height differences of construction artifacts. • Leveling is the general term applied to any of the various processes by which elevations of points or differences in elevation aredetermined. 3 PRATEEK SHARMA R.T.U / G.I.T Jaipur Surveying (3CE4-05) CIVIL ENGG./ III SEM 1.2 Levelling Terms Basicterms: • Vertical line- A line that follows the local direction of gravity as indicatedby a plumbline. • Level surface - A curved surface that, at every point is perpendicular tothe local plumb line (the direction in which gravityacts). • Level line - A line lying in a level surface is a level line. It is thus a curved line normal to the plumb at all points. In field surveying, it is defined by the direction of a freely suspended plumb-bob. • Horizontal plane - A plane perpendicular to the local direction of gravity.In plane surveying, it is a plane perpendicular to the local verticalline. • Horizontal line - A line in a horizontal plane. In plane surveying, it is aline • perpendicular to the localvertical. • Vertical datum - Any level surface to which elevations are referenced. Thisis the surface that is arbitrarily assigned an elevation ofzero. 4 PRATEEK SHARMA
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