Surveying

A theodolite is an important instrument used for measuring horizontal and vertical angles in surveying. The system of surveying in which the angles (both horizontal & vertical) are measured with the help of a theodolite, is called Theodolite surveying.

In special instrument, we detailed discuss about hand leveling, abney level, indian pattern clinometer, ceylon ghat tracer, sextant, site square, mining dial, brunton’s compass, pantagraph, eidograph.

In this photogrammetry chapter, we detailed discuss about photogrammetry, aerial photogrammetry, vertical photograph, scale of photograph, datum scale of photograph, average scale of photograph, flying height, ground co-ordinates & length of a line from a vertical photograph, crab, drift, relief displacement, number of photograph required to cover an area, exposure interval, air base, etc.

In this triangulation chapter, we detailed discuss about classification of triangulation, triangulation layout, well condition triangle, trilateration, system of framework, objective of triangulation, ETC.

In this chapter, we detailed discuss about geographic information system, uses of gis, components of gis, global positioning system, remote sensing, type of remote sensing sensor systems.

In plane table surveying we details discuss accessories used in plane table surveying, alidade, tripod, level tube, compass, plumbing fork, setting up the plane table: centering, levelling, orientation, method of plane table survey.

In theory of errors we details discuss theory of errors, occurrence of error, type of error, gross errors or mistakes, systematic or cumulative errors, accidental or random errors, precision, accuracy, true value, true error, most probable value (M.P.V), principle of least square, residual error, law’s of weights, probable error, error in computed result.

In setting out of circular curve we details discuss offsets from long chord, offset from tangent, offset from chord produced in linear method & tape & theodolite/rankine method / tangential / deflection angles, two theodolite method, tachometer method in angular method.

In curve we details discuss about curve, type of curve, basic definitions of curve, elements of circular curve, apex distance, chainage of tangent points, intermediate chord length.

In tacheometry we details discuss about tacheometry, instrument used in tacheometry, tacheometer, stadia rod, stadia system, fixed hair system, movable hair system, tangential system, subtense bar system, theory of tacheometer, distance and elevation through tacheometer when a staff is vertical & staff is perpendicular to line of sight.

In trigonometric levelling, we details discuss about trigonometric levelling, determination of elevation of object when its base are accessible & not accessible & when the two instruments are not in the same vertical plane.

In measurement of area and volume, we details discuss about mid ordinate rule, average offset rule, trapezoidal rule, simpson’s rule for measurement of area & trapezoidal rule / end area method, prismoidal / simpson’s rule for measurement of volume.

In contour, we details discuss about use of contour, contour interval, properties of contour lines, ridge & valley line, overhanging cliff, vertical cliff. Etc.

In levelling, we are details discuss about elevation & altitude, reduced level, mean sea level, bench marks(B.M), horizontal line, vertical line, level line, back sight reading, fore sight reading, intermediate sight reading, method to find reduced level, height of instrument, rise and fall method, inverted staff, correction required in levelling work, distance of visible horizon, reciprocal leveling, collimation error, angular / inclination error, sensitivity of bubble tube, the sensitivity of level tube increases with?.

In traverse survey, latitude and departure, checks in a closed traverse, closing error, relative precision, bowditch’s rule, transit rule are details discuss.

Compass is a survey instrument used for the measurement of horizontal angles and the bearing of a line of sight.Surveyor Compass and Prismatic Compass are discussed in detailed.

Bearing measured from one station to adjacent next station in the direction of traverse is called fore bearing. Back Bearing, Magnetic Declination, Angle of Dip are discussed in detailed.

In compass surveying each control point is established with the help of linear and angular measurements and this process is termed as traversing. Traverse, Meridian, Bearing are discussed in detailed.

In equipment used in chain surveying,we details discuss about surveying chain, types of chain- revenue chain, gunter’s chain, engineer’s chain, metric chain, suitability of chain, unsuitability of chain, units of measurement, tapes-cloth or linen tape, metallic tape, steel tape, invar tape, pegs, arrows, ranging rods, offset rods, plumb bob, clinometer, cross-staff, optical square, prism square, chain survey instruments, distance measuring device, instruments used for various types of measurement

In liner measurements,we details discuss about procedure in chain surveying,basic definition of chain surveying- main station, tie station, main survey line, tie line/ subsidiary line, base line, check line/ proof line, offset, chainage, well conditioned triangle.Correction in chaining,limiting length of offsets.