Leveling, Instruments of Leveling, Bearings (Surveying, ECE)

Height of Collimation method
#KaushalJigar#KaushalJigar

Leveling is the process used to determine a difference in elevation
between two points.
A Level an instrument with a telescope that can be leveled with a
spirit bubble. The optical line of sight forms a horizontal plane,
which is at the same elevation as the telescope crosshair. By
reading a graduated rod held vertically on a point of known
elevation (Bench Mark) a difference in elevation can be measured
and a height of instrument (H.I.) calculated by adding the rod
reading to the elevation of the bench mark. Once the height of
instrument is established, rod readings can be taken on subsequent
points and their elevations calculated by simply subtracting the
readings from the height of instrument.

1. Precision: the settlement where the bubble is very
sensitive as are high magnification power and uses
this type of work and Geodetic Survey businesses
that require high precision.
2. Precision medium: It is less accurate than the first
category and dominated the use of this type in most
engineering projects.
3. low-precision devices: and make this kind of
hardware specifically for the purposes of settlement
approximate as in building projects Ltd. and
settlement cases within short distance.

 Datum line ( M.S.L. ) :- Is the level (line), which are attributed to it
points levels on the surface of the Earth. Which is the average sea level.
 Reduced level ( R.L) :- Is the high point from datum line.
 Benchmark (B .M ) :- Are fixed points information site and attributed
placed in different places until you start racing them when conducting
settlement .
 Back sight ( B.S.) :- Is the first reading taken after placing the device in
any position so that we see the greatest possible number of points
required to find the elevation .
 Fore sight (F.S) :- Is the last reading taken before the transfer device

 Intermediate sight ( I.S.) :- Is reading taken between the back sight and fore
sight reading .
 Elevation of line of sight ( H.I) :- Is the imaginary vertical level determined by
the line of sight to the amount of increase or decrease for sea level .
 Tripod :- is a portable three-legged frame, used as a platform for supporting the
weight and maintaining the stability of some other object.

 A level is an instrument giving
horizontal line of sight and
magnifying the reading at a far
away distance. It consists of the
following parts:
(i) A telescope to provide a line
of sight
(ii) A level tube to make the line
of sight horizontal and
(iii) A leveling head to level the
instrument

 Is a wooden or metal ruler one side runway to meters and centimeters.
And is a ruler of solid wood 2 , 3 , 4 , 5 meters in length and usually 4
meters .

 Step 1: The level tube is brought parallel to any two of
the foot screws, by rotating the upper part of the
instrument.

 Step 2: The bubble is brought to the centre of the level
tube by rotating both the foot screws either inward or
outward. (The bubble moves in the same direction as
the left thumb.)

 Step 3: The level tube is then brought over the third
foot screw again by rotating the upper part of the
instrument.

 Step 4: The bubble is then again brought to the centre
of the level tube by rotating the third foot screw either
inward or outward.

 Step 5: By rotating the upper part of the instrument
through 180 ° , the level tube is brought parallel to first
two foot screws in reverse order. The bubble will
remain in the centre if the instrument is in permanent
adjustment.

 1 – direct leveling a back sight is taken on the rod held at the bench mark
( A ) .
 H..I = E.L.V of B.M. ( A ) + B.S.
 Turning the telescope to bring into view the rod held on point B afore
sight is taken .
 elev. Point B = H .I – F .S
 check the work by the following equation :-
∑ B.S. - ∑ F.S. = Last R.L. – First R.L.

 A level loop is closed either to another Benchmark or back
to the starting Benchmark. To check for errors in the loop
sum the Back sights (BS) and the Foresights (FS). Calculate
the difference between the BS and FS (BSFS).
Algebraically add this difference to the starting elevation, to
yield the closing elevation. This elevation should be within
accepted industry standards tolerances of the closing
Benchmark’s published elevation.

 The azimuth of a line on the ground is its horizontal angle
measured from the meridian to the line.
 In plane surveying, azimuths are generally measured from the
north.
 Azimuths may have values between
0 and 360 degrees.

 The bearing states whether the angle is measured from
the north or the south and also whether the angle is
measured toward the east or west. For example, if a
line has a bearing of S 47° E, the bearing angle 47° is
measured from the south meridian eastward.

 N.E. Quadrant: Bearing equals Azimuth
 S.E. Quadrant: 180° -Azimuth = Bearing and 180° - Bearing
= Azimuth
 S.W. Quadrant: Azimuth - 180° = Bearing and Bearing +
180° = Azimuth
 N.W. Quadrant: 360° -Azimuth = Bearing and 360° -
Bearing = Azimuth

#KaushalJigar#KaushalJigar
Kaushal Mehta … .. twitter@kaushalmehta96
Jigar Patel … ..twitter@jigarpatel_jp

Leveling, Instruments of Leveling, Bearings (Surveying, ECE)

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