The plane table surveying is the fast method of surveying. In this type of surveying plotting of the plan and field observations can be done simultaneously. In case of plane table surveying Geometrical conditions of site are manuscript in the map sheet using plane table and alidade after that topographic details are arranged on the map.
General equipment used for conducting plane table survey are
Plane table
Alidade for sighting (telescopic or simple)
Plumb bob and plumb fork
Compass
Spirit level
Chain
Ranging rods
Tripod
Drawing sheet and drawing tools
Paper clips or screws
Plane table survey is done in 4 steps :-
1. Fixing of table
Fix the plane table to the tripod stand. Arrange the drawing sheet on the plane table using paper clips or thumb screws. The sheet should be in one position from first to last.
2. Leveling of Plane Table
Plane table should be leveled using spirit level. For small works, eye estimation can be ok.
3. Centering of Plane Table
The table should be centered by using plumbing fork. By which we can arrange the plotted point exactly over the ground point.
4. Orientation of Plane Table
Whenever we are using more than one instrument station, orientation is essential. It can be done by using compass or back sighting. In this case, the plane table is rotated such that plotted lines in the drawing sheet are parallel to corresponding lines on the ground.
