Surveying notes for GATE, PSUs - Part 10

Hello there,
How have you been? Here is 10th part of one liners for the preparation of the GATE and PSUs.
All information is learned through books and practical exercises.
  • To find the R.L. of a roof slab of a building, staff readings were taken from a particular set-up of the levelling instrument. The readings were 1.050 m with staff on the benchmark and 2.300 m with staff below the roof slab and held inverted. Taking the R.L. of the B.M. as 135.150 m, the R.L. of the roof slab will be 138.500 m.
  • Operations involved in a spire test are : 1) Sight a well-defined high point on a high building 2) Clamp horizontal plates  3) Depress the telescope and sight a point on the ground nearer to the instrument 4) Change face and repeat the procedure.
  • Accurate centering in plane table surveying is necessary for large scale maps.
  • Exact orientation is more important than accurate centering for small scale maps.
  • The intersection method of plane table surveying is particularly employed for inaccessible points.
  • Plane table survey is useful for open country with good inter-visibility.
  • Simpson's method estimates best the area of an irregular and curved boundary.
  • In a closed traverse, the sum of south latitudes exceeds the sum of north latitudes and the sum of east departures exceeds the sum of west departures. The closing line will lie in N-W quadrant.
  • In reciprocal levelling, the difference in elevation of two points is calculated by taking the average of the differences obtained by taking measurements from two different instrument settings, one at near to first station and second at near to second station.
  • A lemniscate curve between the tangents is transitional throughout,the polar deflection angle of its apex is equal to A/6.
Other parts :

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