PROCEDURE OF FIELD WORK

PROCEDURE OF FIELD WORK

        1. Reconnaissance: Before starting the survey work over the whole area to be surveyed in order to examine the ground and determine the possible arrangement of the framework of survey. During this investigation, surveyor should examine the inter-visibility of the main survey stations. He should ensure the whole area enclosed by main survey line, so also that it is possible to form well-conditioned triangles. He should observe various objects and boundary line carefully and select the survey line in such a manner the object can be located by short offsets. The base line should be preferably be taken through the centre of the area and on fairly level ground.

        2. Index sketch: After preliminary inspection of the area, the surveyor prepare a neat hand sketch showing the arrangement of the framework and approximate position of the objects. He should note the name of the stations on the sketch maintaining some order (clockwise or anticlockwise). The field work should be executed according to this index sketch. The name and sequence of the chain lines should be followed as directed in the index sketch (Fig. 42). The base line should be clearly indicated in the index sketch.

          3.  Marking the stations on the ground: After reconnaissance, stations are marked on the ground by wooden or any kind of pegs. These pegs are generally 2.5 cm square and 15 cm long, and the pointed end. They are driven into the ground firmly, and there should be the height of 2.5 cm above the ground. The station point is marked with a cross so that it can be traced if the peg is removed by somebody (Fig. 43.a).

        4. Reference sketch: To take precaution against station pegs being removed or missed, a reference sketch should be made for all main stations. It is nothing but a hand sketch of station showing at least two measurements from some permanent objects. A third measurement also be taken (Fig. 43.b).

      5.Taking measurement survey lines and noting them in the field book: Ranging and chaining is started of the base line, which should be measured carefully. The magnetic bearings of the base line are measured by prismatic compass. These measurements are noted in the field book showing the offsets to the left or right according to their position. Then the other survey lines are ranged and chained maintaining the sequence of the traverse (i.e. AB, BC, CD, etc.). the offsets and other field records are noted simultaneously. The check lines and tie lines are also measured and noted at the proper place. The station marks are preserved carefully until field work is completed.      

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