What is precise leveling in surveying?
Precise levelling is a particularly accurate method of differential levelling which uses highly accurate levels and with a more rigorous observing procedure than general engineering levelling. A reduced level is the vertical distance between a survey point and the adopted level datum.
Which levelling is most accurate levelling?
Differential leveling
There are three leveling techniques: differential, trigonometric, and barometric. Differential leveling is the most accurate of the three methods.
What is datum in levelling?
Datum: this is a horizontal plane of known height to which the elevation of all other points is referenced. The mean sea level is the level generally adopted as a datum. Reduced level (RL): this is the height or elevation above the point adopted as the site datum for the purpose of establishing levels.
Which instrument is mainly designed for precise levelling work?
surveyor’s level, instrument used in surveying to measure the height of distant points in relation to a bench mark (a point for which the height above sea level is accurately known). It consists of a telescope fitted with a spirit level and, generally, mounted on a tripod.
Which levelling staff is used for precise levelling work?
and an invar precision levelling staff are commonly used.
What is height of collimation method?
The collimation method is the height-of-instrument method of leveling whereby fore-and-aft readings are made on a leveling staff by an instrument placed intermediately so that the rise or fall between the fore station and the back station is shown by a change in the staff reading. See Also: rise and fall. ii.
What is a datum in engineering?
A datum is a plane, a straight line, or a point that is used as a reference when processing a material or measuring the dimensions of a target.
What are the different types of leveling staves?
There are usually three forms of self-reading staff. They are solid staff, folding staff and telescopic staff.
What is theodolite used for?
theodolite, basic surveying instrument of unknown origin but going back to the 16th-century English mathematician Leonard Digges; it is used to measure horizontal and vertical angles. In its modern form it consists of a telescope mounted to swivel both horizontally and vertically.
Which leveling rod is used for precise work?
A level staff, also called levelling rod, is a graduated wooden or aluminium rod, used with a levelling instrument to determine the difference in height between points or heights of points above a vertical datum.