What does HPC mean in surveying?

There are two accepted methods of booking observations – Rise and Fall method and Height of the Plane of Collimation method (HPC/HOC).

How do you calculate HPC in surveying?

A second way to calculate the reduced levels is by using the Height (level) of collimation line (or plane). From the above numerical example, Height of Plane of Collimation (HPC) = +120.000 + 1.135 = +121.135m (as from Figure 2) => RLB = HPC – (Staff Reading at B)

What are the different equipment used in leveling field work?

Following are the types of different levels used for leveling in surveying:

• Dumpy Level. Dumpy level is the most commonly used instrument in leveling.
• Y Level. Y level or Wye-level consists y-shaped frames which supports the telescope.
• Cushing’s Level.
• Tilting Level.
• Cooke’s Reversible Level.
• Automatic Level.

Which instrument can be used for leveling survey?

The theodolite (q.v.), or transit, is used to measure horizontal and vertical angles; it may be used also for leveling.

What is foresight and backsight in surveying?

h) Back sight : (B.S.) – The first sight taken on a levelling staff held at a point of known elevation. B.S. enables the surveyor to obtain HI +sight i.e. Height of Instrument or line of sight. i) Fore Sight : (F.S.) – It is the last staff reading taken from a setting of the level. It is also termed as minus sight.

How do you calculate RL by HI method?

Rl of Hi = Rl of CP + BS.

How many axes are there in levelling instrument?

A modern theodolite consists of a movable telescope mounted within two perpendicular axes—the horizontal or trunnion axis, and the vertical axis.

What are leveling devices?

Levelling instruments are employed for determining the relative heights of different points on the earth’s surface. A level essentially consists of a telescope to which a bubble tube is attached such that the axis of the bubble tube and the line of collimation of the telescope are parallel to each other.