Definition of backsight 1 surveying : a reading of the leveling rod in its unchanged position when the leveling instrument has been taken to a new position. 2 surveying : a sight directed backward to a previous station.
What is back sight and fore sight in levelling?
The backsight is the first staff reading taken after the level is set up and leveled at the point. Foresight (FS) or Foresight reading. It is a staff reading taken on a point whose elevation has to be determined through levelling process.
What is the fore sight reading?
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.
Why do you take a backsight?
A backsight (BS) is a sight taken with the level to a point X of known elevation E(X) , so that the height of the instrument HI can be found. Backsights are also called plus sights (+ S), because you must always add them to a known elevation to find HI.
What is a foresight in surveying?
foresight-1A point to which an instrument sighting is made for measuring or establishing its elevation and/or its horizontal position.
What are the different types of site survey?
- Existing buildings (including valuation, measured surveys, structural surveys, structural investigations, condition surveys, and demolition surveys).
- Geological and geotechnical.
- Topographical surveys, perhaps including laser scanning, Lidar or photogrammetry.
- Contamination.
What are the 3 types of land survey?
- ALTA / ACSM Survey. This type of survey is typically conducted for use in the buying and selling of real estate.
- Boundary Survey.
- Construction Staking.
- Location Survey.
- Right-of-Way Survey.
- Topographic Survey.
What is in a site survey?
A site survey is the examination of a location or spot in order to obtain data or information. This information includes feasibility reporting and estimation of cost and the time required to perform a certain task.
What is a site survey in construction?
What are Site Surveys? Site surveyors inspect the area of a proposed construction project. They gather information for a design or an estimate to complete the initial tasks required. It can also determine a precise location, access and best layout for the site.
How do you calculate backsight?
Measure a backsight on A (for example, BS = 1.89 m). Measure on C a foresight FS = 0.72 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.
What is foresight and backsight?
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.