The purpose of cross-sections leveling is to understand the undulation of the ground surface transverse to the center line or profile line. The Cross-Section are taken perpendicular to the center line of the alignment at some regular intervals.
The length of the cross-section depends on the type of work. In road work, it may happen 30 to 60 m, in railway 200 to 300 m, In mining, it may occur full length or breadth on either side of the center line. They are taken at each 30 m station on the center line. In mining generally probably 10 or 15 m grid systems.
Requirement:-Level instrument, Theodolite, Total station, Tape or chain and material for Mark on the ground.
Process:- (1) Set the level instrument between A and B ones side of the profile line, and make necessary temporary adjustment.set the line cs-1 right angle to the line A-B, from uses of tape, chain and theodolite. From the level, instrument take first reading on A and Book as B.S reading in level book for zero chainage. Elevation of point A comes from profile Levelling. Take intermediate reading on along with cs-1 line at the required length. complete the Levelling process, and booked in level book.
(2)Another Process of Cross -Sectioning use in the mining:- Cross-section measurement in opencast mine has important in volume measurement, shown mines section, coal stock measurements. Generally, two types of methods used for measurement with the help of the Total station.
Requirement:- Total station with all it's accessories. Communication accessories etc.
(A) In the above figure, for example, to take the measurement along section line 1400.Set the total station at that place from where section line 1400 complete visible.layout the section line 1400 on the according mining conditions on the ground and take the reduced level
(B) In the second method, the measurement of the mine complete by taking randomly point reading according to mine benches. Calculate RL where require by interpolation,
(3) In this process the section line Mark by use of theodolite, Total station and the level instrument. In the above picture, a line AB is marked on the mine bench according to visible Capacity and bearing of this line take by use of theodolite or T.S. The coordinates of nothing on any grid calculate by formula = Angle of TAN= Difference of departure ÷ Difference of latitude and the distance from Instrument station to the next grid is calculated by formula = Departure÷Angle of sin.
Procedure:- Set the theodolite or Total station on point A. Temporary adjustment makes.
Take the bearing of the line AB. In the above figure, the coordinate of point A departure=1163.1595 and Latitude=1237.8380 and bearing is 99°19'30''. For use of the above formula.The length of the line instrument station A to grid 1200 = 36.8405÷sin99°19'30''= 37.3339. Then measure the distance 37.3339 m from instrument Station A get grid 1200 on ground. The northing value of grid for line AB is also calculated formula.Difference of latitude from point A for grid 1200 = 36.8405÷Ta99°19'30''= -6.0493 m . Then northing value on grid 1200= 1237.8380- 6.0493 = 1231.7885m.
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