Intersection Method || Tripod || civil || Blub || plumbing Fork

Instruments Required for Plane Table Survey:
Tripod
Plane Table
Plumbing Fork
Level
Magnetic needle compass
Alidade
Measuring Tape
Ranging Rods (For demonstration purpose)
Other accessories
28in x 22in drawing sheet
Scotch Tape
Chisel pointed Pencil
Eraser
Procedure:
Select two instrument stations P and Q, such that all the points or details to be located are visible from both the stations.
Now set the table on P and make it centered and level.
Using the plumbing form locate the ground station on the sheet i.e. p, such that the point p on the sheet is exactly over the point P on the ground.
Measure the distance between P and Q.
Now using the alidade pivoted at P orient the table so that other instrument station Q is sighted and clamp the table and draw a line along the fidicual edge of the alidade according to a suitable scale. This line pq is a base line and hence must be measured and drawn accurately
With the alidade pivoted on p sight other details and draw rays as a’, b’ c’, d’ etc as shown in Figure 0-1
Now shift the table to station Q and make it centered and leveled such that point q on sheet is exactly above the Q on the ground
With the alidade placed along line pq orient the table and back sight the station P and clamp the table.
With the alidade pivoted on q sight other details and draw rays as a’’, b’’ c’’, d’’ etc as shown in Figure 0-2
The intersection of a’, b’ c’, d’, e’ with a’’, b’’ c’’, d’’, e’’ are named as a, b, c, d, e respectively. Join a, b, c, d, e as shown in Figure 0-3