--- title: "Principles of surveying with examples" subject: "Surveying I" chapter: 1 key: "semester_3/surveying_i:principles-of-surveying" source: https://www.bctengineer.com/q/semester_3/surveying_i/principles-of-surveying site: BCT Engineering --- # Principles of surveying with examples Surveying I · Chapter 1: Introduction - Asked in: 2081 Baisakh, 1+3 marks; 2080 Baisakh, 2+2 marks; 2080 Bhadra, 1+3 marks; 2078 Bhadra, 4 marks; 2076 Chaitra, 4 marks; 2075 Chaitra, 4 marks; 2075 Asoj, 4 marks; 2074 Chaitra, 4 marks; 2064 Jestha, 6 marks (asked 9 times) - Video: [Definitions Principles Objective Classification - Introduction to Surveying - Surveying 1](https://www.youtube.com/watch?v=2bZTNGheX3o) — Ekeeda - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_3/surveying_i/principles-of-surveying - Whole chapter: https://www.bctengineer.com/md/semester_3/surveying_i/chapter-1 ## Question What are the fundamental principles of surveying? Describe any two of them with suitable examples. ## Short answer Surveying relies on working from whole to part, where a precise control framework is established first and details are filled in later, preventing error accumulation. The second principle is fixing a new point by at least two independent measurements from fixed stations, such as two distances or a distance and angle, with a third check measurement. ## Answer Surveying is based on two fundamental principles. Every survey, large or small, follows them to control error and to fix points correctly. 1. **Working from whole to part.** 2. **Fixing the position of a new point by at least two independent measurements** from points already fixed. (A third working rule, always check the measurements, supports both.) #### Principle 1: Working from whole to part First a framework of control stations is fixed over the whole area with high accuracy (a few widely spaced stations, using precise instruments). Then the area is divided into smaller parts and the details are surveyed inside this framework with less precise methods. Reason: errors do not accumulate. If we worked from part to whole, small errors of each part would add up and grow. If a mistake occurs in a small part, it stays inside that part and does not spoil the whole survey. Example: For a large town map, main triangulation stations are fixed first with a theodolite. Inside each big triangle, smaller chain-survey triangles are laid and the buildings, roads and boundaries are located from them by offsets. ```text Whole: big triangle ABC (precise) A /\ / \ / .. \ Part: small triangles /______\ and details inside B C ``` #### Principle 2: Location of a point by two independent measurements A point can be located from two known points A and B by any one of these pairs of measurements: - two distances (A-P and B-P, intersection of two arcs), - one distance and one angle (e.g. angle at A and distance AP), - two angles (angles at A and B, intersection of two lines), - a perpendicular offset from a known line and the distance along that line. Example: In chain surveying a tree P near line AB is fixed by measuring the distance along AB to the foot of the perpendicular (chainage) and the length of the perpendicular offset. A third measurement, the tie distance to a point on the line, is taken as a check. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. Why is the 'working from whole to part' principle followed? A. Errors do not accumulate, and a mistake in one part stays inside that part B. It lets the details be measured with the most precise instruments C. It removes the need to check measurements D. It makes the survey cheaper because no control stations are required Answer: A. A precise control framework is fixed first and details are fitted inside it, so errors are localised instead of adding up. (Key point: Why whole to part) 2. How should a new point be fixed according to the second principle? A. By one measurement from one fixed point B. By measuring only angles at the new point itself C. By at least two independent measurements from points already fixed D. By estimating its position by eye and checking later Answer: C. A point needs at least two independent measurements (distances, angles, or an offset and chainage) from known points. (Key point: Two measurements) 3. What would happen if the survey were done from part to whole? A. Errors would cancel out automatically B. Small errors of each part would add up and grow C. The accuracy would be uniform over the area D. Only the control stations would be affected Answer: B. Working part to whole lets errors accumulate and distort the survey, which is why whole to part is used. (Key point: Part to whole) 4. In chain surveying, how is a tree P near line AB fixed? A. By two angles measured at P only B. By the area of the triangle formed with A and B C. By the bearing of line AB alone D. By the chainage of the foot of the perpendicular and the perpendicular offset length Answer: D. The chainage along AB plus the perpendicular offset are two independent measurements that fix P; the tie distance checks it. 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