i) Geodatic Survey
⇒Σangle < 540°
⇒By triangulation
ii) Plane Survey
⇒dam, highway, railway
⇒area < 260 km²
⇒195km²
iii) Topographical syr : natural features valley,lake,river
iv) Hydrographic syr : large water bodies
v) Engineering syr : design & construction of new routes ,roads & railway
vi) Geological syr : diff strata of earth surface
vii)Cadastral syr :plans of property boundaries for legal purpose. Revenue chain used
viii) Astronomic syr : azimuths , latitude, longitude, absolute location of a point on earth
ix) Longitudinal land syr : linear bars used
★SOI : toposhot 1:50000.
⇒Archeological syr : old & nelic str info.
★traffic(topographic)→Reconnaissance→Preliminary →Detail/location/final survey.
PRINCIPLE OF SURVEYING:
a) work from whole to part : localise error & prevent their accumulation
b) Locate a point by atleast two measurement
⇒two side
⇒one side one angle
⇒two angle
⇒one side one right angle
SCALE:
⇒engineer scale : 1cm = 30m , RF = 1/3000
⇒Repersentative fraction (RF) = map distance/ground distance.
Types of scale :
i) Plain scale : two dimensions, units & tenth
ii) diagonal : three dimensions ,units, tenth & hundreds :m dm cm
iii) Shrunk scale = Original scale x shrinkage factor (SF)
⇒SF or SR = shrunk/original length = shrunk RF/original = Shrunk scale/original.
⇒Graphical scale not affected due to shrinkage of map ∴ better than Numerical scales.
⇒1/100 is larger than 1/1000
⇒ correct L & A = Lm / S.R. & Am / (SR)².
★correct = ( std ± δ ) x L,A,V. (+ longer than std & -ve shorter than std.)
iv) Vernier : (DRE 10 = 9 11 19)
a) Direct vernier
⇒shorter than div. main scale
⇒reading /graduatⁿ in directⁿ of main scale
⇒n div of direct = ( n - 1 ) div. of main scale.
b) Retrograde Vernier.
⇒longer than div. of main scale
⇒opp direction of main scale
⇒n div = (n + 1) div of main scale
c) Extended Vernier.
⇒ n div = ( 2n - 1 ) div of main scale.
⇒Least count of main scale = s/n,
s = value of one smallest div. of main scale
n = no. of div. on the Vernier.
Building = 1 : 1000
Town planing = 1 : 5000
Route (Rd & rail) = 1 : 10000
Topogrphical syr = 1 : 25000
Error = measured - true.
Correction = True - measured.
i). Cumulative/systematic errors :
⇒ ∝ L ,(+ve or -ve )
⇒may increase or decrease with increase in measurement
⇒ occur in same direction & tend to accumulate
ii). Compensating/Random errors
⇒ ∝ √L , (
⇒occur in both direction & tend to compensate.
★permissible error hilly/rough region = 1 in 250.
Instruments:
⇒Horizontal distance = tape ,chain, tachometer & EDM
⇒Vertical distance = Tacheometer & Level
⇒H. Angle = compass, theodolite, total station & sextant.
⇒V.Angle = sextant, clinometer, theodolite.
⇒Paralex bar: parallex diff, use with mirror stereoscope.
⇒Substance bar: horizontal distance only.
⇒minidraft = T square + set square.
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