---
title: "Principle of chain surveying"
subject: "Surveying I"
chapter: 3
key: "semester_3/surveying_i:principle-of-chain-survey"
source: https://www.bctengineer.com/q/semester_3/surveying_i/principle-of-chain-survey
site: BCT Engineering
---

# Principle of chain surveying

Surveying I · Chapter 3: Chain Survey

- Asked in: 2078 Kartik, 4 marks; 2068 Chaitra, 4 marks; 2074 Asoj, 4 marks (asked 3 times)
- Video: [Introduction to Chain Surveying || Principle of Chain Surveying || Chain Surveying || Surveying](https://www.youtube.com/watch?v=oOK23QA8I10) — Mukesh Kumar
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_3/surveying_i/principle-of-chain-survey
- Whole chapter: https://www.bctengineer.com/md/semester_3/surveying_i/chapter-3

## Question

What is chain surveying? Explain the principle of chain surveying.

## Short answer

Chain surveying uses only linear measurements. The principle is to cover the area with a network of well-conditioned triangles, whose sides are measured and details located by offsets from chain lines. The work follows working from whole to part, using check lines to control errors.

## Answer

**Chain surveying** is the type of surveying in which only linear measurements (with a chain or tape) are made in the field, without angular measurements. It is suitable for small, fairly flat areas with few details.

#### Principle
The area to be surveyed is covered by a **network of well-conditioned triangles**, because a triangle is the only simple figure that can be plotted from the lengths of its three sides alone. The sides (chain lines) are measured in the field. The details (buildings, roads, boundaries) are then located by measuring perpendicular or oblique **offsets** from the chain lines. On paper, the triangles are plotted to scale by intersecting arcs, and the details are plotted from the offsets.

```text
        C
       /|\ 
      / | \       triangle ABC: sides measured
     /  |  \      tie line / check line shown
    A---+---B     offsets to details from AB, BC, CA
```

The work follows the principle of **working from whole to part**: the big triangles (framework) are made first and the details are surveyed from them. To avoid accumulation of errors, check lines are measured.

## Check yourself

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

1. What is the basic principle of chain surveying?
   A. Measure all horizontal angles with a theodolite and plot by polar coordinates
   B. Cover the area with a network of well-conditioned triangles whose sides are measured, and fix details by offsets
   C. Level the whole area first and plot contours from the reduced levels
   D. Run one long traverse and fix details by magnetic bearings
   Answer: B. A triangle can be plotted from its three sides alone, so only linear measurements are needed; details are located by offsets from the sides. (Key point: Principle of chain surveying)

2. Why is the triangle chosen as the framework figure in chain surveying?
   A. It has the largest area for a given perimeter
   B. Its angles always add up to 360 degrees so closing is automatic
   C. It is the only simple figure that can be plotted from the lengths of its sides alone
   D. Its sides never need to be measured exactly
   Answer: C. Without angular measurement, a figure must be fixed by lengths only; a triangle is rigid by its three sides, while a quadrilateral is not. (Key point: Why triangles)

3. What does the principle of 'working from whole to part' mean here?
   A. Details are surveyed first and the framework is fitted to them
   B. The whole area is chained in one single line
   C. Small triangles are measured first and joined into larger ones
   D. Big framework triangles are fixed first and the details are surveyed from them
   Answer: D. Errors would accumulate if small parts were built up; the control framework is fixed first and details hang on it. (Key point: Whole to part)

4. Which description of chain surveying is correct?
   A. Only linear measurements are taken in the field; no angles are measured
   B. Both linear and angular measurements are taken with theodolite
   C. Only levels are taken
   D. Only angles are measured with a chain
   Answer: A. Chain surveying uses a chain or tape only, suited to small, fairly flat areas with few details. (Key point: Chain surveying defined)

## Related in Surveying I

- [Principle of chain surveying; well-conditioned triangle](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Achain-principle-well-conditioned-vs-error) — Surveying I, chapter 3
- [Field procedure of chain surveying](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Afield-procedure-chain-survey) — Surveying I, chapter 3, asked 4×
- [Chain survey principle and operations](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Achain-principle-and-field-procedure) — Surveying I, chapter 3, asked 2×
- [Principle of chain survey; types of offsets](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Achain-principle-and-offsets) — Surveying I, chapter 3
- [Engineering surveying; two-way principle application](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Aengineering-surveying-two-way-angle) — Surveying I, chapter 1
- [Obstacles in chain survey and remedies](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Aobstacles-chain-survey) — Surveying I, chapter 3, asked 4×