Procedure of theodolite methods in setting out of stage?

Answer 1

Procedure:-

1) Let LOM is the horizontal angle to be measured as shown in fig. O is the station point

fixed on the ground by a peg. Set up the theodolite over the peg 'o' and level it

accurately.

2) Set the horizontal graduated circle vernier A to read zero or 360° by upper clamp

screw and slow motion screw. Clamp the telescope to bisect the bottom shoe of the

flag fixed at point 'L' and tighten the lower clamp. Exactly intersect the centre of the bottom shoe by means of lower slow motion screw. Check that the face of the

theodolite should be left and the telescope in normal position.

3) Check the reading of the vernier A to see that no slip has occurred .Also see that the

plate levels are in the centre of their run. Read the vernier B also.

4) Release the upper clamp screw and turn the theodolite clockwise. Biset the flag

bottom shoe fixed at point M by a telescope. Tighten the upper clamp screw and

bisect the shoe exactly by means of upper slow motion screw.

5) Note the reading on both the vernier to get the approximate value of the angle LOM.

6) Release the lower clamp screw and rotate the theodolite anticlockwise ai azimuth.

Bisect again the bottom shoe of the flag at 'L' and tighten the lower clamp screw. By

means of slow motion screw bisect exactly the centre of the shoe.

7) Release now the upper clamp screw and rotate the theodolite clockwise. Bisect the

bottom shoe of the flag fixed at M and tighten the upper clamp screw. By means of

slow motion screw bisect exactly the centre of the shoe. The vernier readings will bw

now twice the of the angles.

8) Repeat the process until the angle is repeated the required number of times (usually

3). Add 360° for every complete revaluation to the final reading and divided the total

angle by number of repetitions to get the value of angle LOM.

9) Change the face of the theodolite the telescope will now be inverted. Rrpeat the

whole process exactly in the above manner and obtain value of angle LOM.

10)The average horizontal angle is then obtained by taking the average of the

two angles obtained with face left and face right.

11)Usually three repetitions face left and three with face right should be taken and the

mean angle should be calculated.

by

M.laxminarayaan