Concept Notes
1. Introduction
- Chain Surveying is the simplest and oldest method of surveying.
- It is mainly suitable for small, level, and open areas where details are less and accuracy required is moderate.
- Instruments: Chain, Tape, Arrows, Ranging rods, Pegs, Cross staff, etc.
2. Principles of Chain Surveying
- Principle of Working from Whole to Part
- First, establish a large framework of triangles (main survey lines).
- Then, divide into smaller triangles (sub-triangles) for details.
- Reduces accumulation of errors.
- Principle of Triangulation
- Area is divided into triangles because a triangle can be plotted easily with three known sides.
- Triangles should be well-conditioned (not too acute or obtuse).
- Best triangle: having angles between 30° to 120°.
- Principle of Accuracy by Checking
- Provide check lines and tie lines to detect mistakes.
- Example: A check line connects two fixed points to ensure correctness.
- Principle of Simplicity in Layout
- Main survey lines should form a simple framework, avoiding unnecessary complexity.
- Base line is chosen as long, straight, and clear line.
- Principle of Intervisibility
- End stations of survey lines should be mutually visible for accurate ranging.
- Obstacles (trees, hills) should be avoided.
3. Types of Lines in Chain Surveying
- Main Survey Lines – Framework of triangles.
- Base Line – The longest line, foundation of survey.
- Check Line – To check accuracy of framework.
- Tie Line – Joins interior points to main lines for detailing.
4. Example
If a rectangular plot is to be surveyed:
- First select base line along longer side.
- Then create main triangles covering the whole plot.
- Use tie lines to take details of boundaries or buildings.
⚙️ Formulas
Chain surveying is principle-based, mostly no numerical formulas. But related geometry of triangles is used.
- Length of diagonal in a rectangle:
Area of triangle (Heron’s formula):
where 
Well-conditioned triangle rule:
🔟 10 MCQs
Q1. Chain surveying is most suitable for:
a) Hilly areas
b) Small level ground
c) Large city survey
d) Railway alignment
Q2. The fundamental principle of chain surveying is:
a) Traverse method
b) Triangulation
c) Traversing + Triangulation
d) Compass bearing
Q3. A well-conditioned triangle should not have angle less than:
a) 15°
b) 20°
c) 30°
d) 60°
Q4. The longest line in a chain survey is:
a) Tie line
b) Base line
c) Check line
d) Main line
Q5. A tie line is used to:
a) Establish check
b) Join interior details
c) Form base
d) Mark boundary
Q6. A check line in chain surveying is meant for:
a) Measuring long distances
b) Ensuring accuracy
c) Dividing triangles
d) None
Q7. The best triangle in chain surveying has angles:
a) 20°, 40°, 120°
b) 30°, 60°, 90°
c) 10°, 80°, 90°
d) 25°, 25°, 130°
Q8. The principle of “whole to part” is used to:
a) Reduce errors
b) Increase errors
c) Increase speed
d) Avoid measurements
Q9. Which instrument is not used in chain surveying?
a) Cross staff
b) Ranging rod
c) Prismatic compass
d) Pegs
Q10. The area of a triangle with sides 5 m, 6 m, 7 m is:
a) 12 m²
b) 14 m²
c) 16 m²
d) 10 m²
✅ Answer Key
| Q | Answer |
|---|---|
| 1 | b |
| 2 | b |
| 3 | c |
| 4 | b |
| 5 | b |
| 6 | b |
| 7 | b |
| 8 | a |
| 9 | c |
| 10 | b |
🧠 Explanations
- Q1: Chain surveying is suitable for small, level areas → (b).
- Q2: Principle is triangulation → (b).
- Q3: Triangle should not be less than 30° → (c).
- Q4: Base line is the longest line → (b).
- Q5: Tie line joins interior details → (b).
- Q6: Check line ensures accuracy → (b).
- Q7: 30°, 60°, 90° is well-conditioned → (b).
- Q8: Whole to part reduces errors → (a).
- Q9: Compass not used in chain surveying → (c).
- Q10: Using Heron’s formula, area = 14 m² → (b).
🎯 Motivation / Why Practice Matters
Chain surveying is a basic but scoring topic in ECET Civil.
- Questions are mostly conceptual → quick to solve.
- Understanding “principles” helps in advanced topics like compass surveying and theodolite surveying.
👉 Practicing small numericals (triangle area, distances) ensures accuracy and avoids silly mistakes.
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