survey report on theodolite traversing

OBJECTIVES
To know the advantages of bearing and their use in various survey works.
To be familiar with the checks and errors in a closed traves and solve them.
To be familiar with various types and methods of traves surveying fot detailing.
To know well about the travese computation and be fluent in it.
INSTRUMENTS REQUIRED
Tape
Ranging rod
Pegs
Hammer
Theodolite with tripod
Prismatic compass
THEORY
Travesing is that type of survey in which member of connected survey lines from the frame work and the direction and lengths of the survey lines are measured with the help og an angle (or direction) measuring instrument and a tape(or a chain). When the lines form a circuit which ends at the starting points, it is known as closed traverse. It the circuit ends else where, it is said to be an open traverse.
The close traverse is suitable for locating the boundaries of lakes, wood etc and for the survey of large araes, whereas open traverse is suitable for surveying a long narrow strip of land as required for a road or canal or the coast line.
The main principle of traverse is that a series of the straight line are connected to each other and the length and direction of each lines are known. The traverse lines or legs should be passed through the area to be surveyed. The joins of two points of each lines is known as traverse station and the angle at any station between two consecutive traverse legs is known as traverse angle.
Traversing by compass and theodolite
The traverse in which the length of the traverse leg is directly measured by taping or chainging on the ground and the bearing of the traverse station is measured by the compass is called compass traversing. The traversing in which the length between two stations of the traverse is measured directly by chaining or taping in the ground and angle of the station is measured by the theodolite is called theodolite traversing.
Procedure
First of all the traverse stations were fixed around the given area to the surveyed keeping in the ratio of traverse legs 1:2 for major and 1:3 for minor traverse. The number of the stations were choosen in convinient manner.
Measurement of the horizontal distance of the traverse legs were taken by the tape. Two ways ie forward and backward measurement of each traverse leg were taken.
Now, with the help of theodolite two sets of horizontal angle between the traverse legs were measured.
At the same time, one set of vertical angle were also measured.
The height of the instrument in every set up of theodolite was also measured.
Now, with help of level machine, the height of signal or say RL of each stations with respect to the given assumed BM was measured.
With the help of prismatic compass, magnetic bearing of one traverse line was measured.
Observation and calculations

Comments and discussions
Here the traverse computation is done in a tabular form, called Gale’s Traverse table. For complete traverse computations, following steps were carried out:
The interior angles were adjusted to satisfy the geometrical conditions, ie sum of interior angles to be equal to (2n-4)x90
Starting with observed bearing of one line the bearings of all the others lines were calculated.
Consecutive co-ordinates ( latitude and departure ) were calculated.
∑ L and ∑ D was calculated.
Necessary corrections were applied to the latitudes and departures of the lines so that ∑ L=0 and ∑ D=0. The corrections were applied by the transit rule.
Using the corrected consecutive co-ordinates, the independent values…….. were calculated.
The correct lengths and the correct bearings of the traverse lines were also calculated using the corrected consecutive co-ordinates.
ie true length (l) =√(L^2+D^2 )
true bearing (θ) = tan-1( D/L )