---
title: "Principle methods of levelling"
subject: "Surveying I"
chapter: 5
key: "semester_3/surveying_i:list-principle-methods-leveling"
source: https://www.bctengineer.com/q/semester_3/surveying_i/list-principle-methods-leveling
site: BCT Engineering
---

# Principle methods of levelling

Surveying I · Chapter 5: Leveling

- Asked in: 2080 Bhadra, 1+3 marks
- Video: [Levelling #Principle of Levelling #Objective of Levelling](https://www.youtube.com/watch?v=LoWjyMAKtBE) — Civil Samajh
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_3/surveying_i/list-principle-methods-leveling
- Whole chapter: https://www.bctengineer.com/md/semester_3/surveying_i/chapter-5

## Question

List the principle methods of levelling and describe any one method.

## Short answer

Methods: direct (spirit), trigonometric, barometric, hypsometric, and stadia levelling. In direct levelling, a level sets a horizontal line of sight; staff readings on points give HI = RL+BS, and RL = HI−reading. The arithmetic check ΣBS−ΣFS = last RL−first RL verifies the reduction.

## Answer

#### Principle methods of levelling

1. **Direct (spirit) levelling:** staff readings with a level.
2. **Trigonometric levelling:** from the vertical angle and the distance.
3. **Barometric levelling:** from the atmospheric pressure.
4. **Hypsometric (boiling point) levelling:** from the boiling point of water.
5. **Stadia levelling** (tacheometric) and **GPS/total station levelling** are also used in modern work.

#### Direct (spirit) levelling

The differences in level are found with a level and a vertical staff. A horizontal line of sight is obtained from the level.

1. Set the level at a convenient point, level it with the foot screws and bubble.
2. The BS is read on a BM of known RL; the HI is found: $HI = RL + BS$.
3. The staff is held at the other points (IS), and finally the FS is read at a change point; $RL = HI - \text{staff reading}$.
4. The instrument is moved ahead; the staff stays at the CP and a new BS is taken. The process continues up to the last point.
5. The readings are booked in a level field book and checked: $\Sigma BS - \Sigma FS = \text{last RL} - \text{first RL}$.

It is the most accurate method and is used for fixing benchmarks, roads, canals, and building sites.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Which method finds elevation differences from the vertical angle and the distance?
   A. Barometric levelling
   B. Trigonometric levelling
   C. Hypsometric levelling
   D. Direct levelling
   Answer: B. Trigonometric levelling computes the height difference from a measured vertical angle and horizontal distance. (Key point: Methods list)

2. Hypsometric levelling determines elevation from:
   A. Staff readings
   B. Atmospheric pressure
   C. The boiling point of water
   D. Vertical angle
   Answer: C. The boiling point of water falls with altitude, so it indicates elevation; barometric levelling uses pressure. (Key point: Hypsometric levelling)

3. In direct levelling, how is the height of instrument obtained after a BS on a BM?
   A. HI = RL + FS
   B. HI = BS - FS
   C. HI = RL + BS
   D. HI = RL - BS
   Answer: C. The line of sight is above the BM by the BS reading, so HI = RL + BS; then RL = HI - staff reading. (Key point: Direct levelling HI)

4. When the instrument is moved ahead in direct levelling, what happens to the staff at the CP?
   A. It is moved to the BM
   B. It is removed and a new CP chosen
   C. It is read as an IS
   D. It stays on the CP and is read as a new BS from the new setup
   Answer: D. The staff stays at the CP so that the FS and next BS are on the same point, linking the levels. (Key point: Level shifting)

## Related in Surveying I

- [Levelling methods; errors eliminated by balancing](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Aprinciple-methods-leveling-balancing-sight) — Surveying I, chapter 5, asked 2×
- [Reciprocal levelling: why and formula](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Areciprocal-leveling-derivation) — Surveying I, chapter 5, asked 3×
- [Reciprocal levelling: RL of A, B at 1160.18 m](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Areciprocal-leveling-rl-b-1160-18) — Surveying I, chapter 5, asked 2×
- [Reciprocal levelling: RL of A, B at 1260.18 m](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Areciprocal-leveling-rl-b-1260-18) — Surveying I, chapter 5, asked 2×

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