Fore sight (FS) short for "fore sight reading", the last staff reading taken before changing the instrument to the other position. It is the staff reading taken on point whose RL is to determined. This sight is considered as negative and deduced from Height of Instrument to determine RL of the point.
How do you determine backsight and foresight?
https://www.youtube.com/watch?v=v0oFRqnI0GY
How do you find foresight in surveying?
For angle measuring or line prolongation, the foresight is the angle measurement on the graduate( horizontal circle of the instrument (set or to be read and recorded) when the vertical cross hair of the instrument is visually coinciding with the foresight point or with a marker in the vertical plane through the
What is the purpose of backsight?
backsight-1 A point used to determine the elevation and/or angular orientation of the surveying instrument.
How is foresight calculated?
Foresight is taken at S2 and its elevation (98.245m) is determined by subtracting the foresight (3.570m) from the height of the instrument (101.815 m). In this way, elevation of points are calculated by Height of instrument method.
What is a foresight in survey?
foresight-1A point to which an instrument sighting is made for measuring or establishing its elevation and/or its horizontal position.
What is a foresight in levelling?
The point where the line of sight meets the levelling staff is point Y. Measure BY. This is called a foresight (FS).
What is backside and foresight?
As nouns the difference between backsight and foresight is that backsight is the rear sight of a firearm while foresight is the ability to foresee or prepare wisely for the future.
What is a turning point in levelling?
A turning point (T.P.) is an intermediate point between benchmarks which provides a temporary point of known elevation for a level circuit between two benchmarks a long distance apart. A turning point may be an iron pin which is driven firmly into the ground at a convenient location.
What is a turning point in civil engineering?
Change point or Turning point (TP) It is a point denoting the shifting of the level. It is a station at which both BS and FS readings are taken. Stable and well defined objects must be chosen as change points for accurate results.
What is the meaning of foresight in survey?
the act of looking forward. surveying a reading taken looking forwards to a new station, esp in levelling from a point of known elevation to a point the elevation of which is to be determinedCompare backsight.
What is backsight and foresight 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 is Backsight calculated?
Measure a backsight on A (for example, BS = 1.89 m). Calculate HI = BS + E(A) = 1.89 m + 100 m = 101.89 m. Find the elevation of turning point C as E(C ) = HI-FS = 101.89 m - 0.72 m = 101.17 m.