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Chapter: Civil Surveying - Control Surveying

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important Questions and Answers: Control Surveying

CiIvil Surveying - Control Surveying

Control Surveying

 

 

1.     Define Tacheometry:

 

i.      Tacheometry is a branch of angular surveying in which the horizontal and vertical distances (or) points are obtained by optional means as opposed to the ordinary slower process of measurements by chain (or) tape.

 

2.     Define Tacheometer:

 

i.      It is an ordinary transit theodolite fitted with an extra lens called analytic lens. The purpose of fitting the analytic lens is to reduce the additive constant to zero.

 

3.     Define Analytic lens:

 

a.     Analytic lens is an additional lens placed between the diaphragm and the objective at a

 

4.     fixed distance from the objective. This lens will be fitted in ordinary transit theodolite. After fitting this additional lens the telescope is called as external focusing analytic telescope. The purpose of fitting the analytic lens is to reduce the additive constant to zero.

 

5.     Define Substance bar:

 

a.     A Substance bar is manufactured by Mr. Kern. The length of the substance bar is 2m (6ft)

 

6.     for measurement of comparatively short distance in a traverse. A Substance bar may be used as a substance base. The length of the bar is made equal to the distance between the two targets.

 

7.     What are the merits and demerits of movable hair method? Merits:

 

i.      Long sights can be taken with greater accuracy than stadia method The error obtained is minimum

 

b.    Demerits:

 

The computations are not quicker Careful observation is essential

 

8.     Fixed hair method:

 

a.     In this method, the stadia wires are fixed (or) fitted at constant distance apart.

 

9.     Staff intercept:

 

a.     The difference of the reading corresponding to the top and bottom stadia wires.

 

10.                        Stadia intercept:

 

a. The difference of the distance between the top and bottom cross hairs. In this method stadia interval is variable. The staff intercept is kept fixed

 

while the stadia

 

b.   interval is variable.

 

11.                        The tangential method:

 

a.     In this method, the stadia hairs are not for taking readings. The readings being taken against the horizontal cross hair.

 

12.                        What are the systems of tacheometry measurements?

 

a.     The stadia system The tangential system

 

b.    Measurement by means of special instrument.

 

13.                        What are the types of stadia system?

 

a.     Fixed hair method, Movable hair method

 

14.                        What is the principle of stadia method?

 

The method is based on the principle that the ratio of the perpendicular to the base is constant to similar isosceles triangle.

 

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