Scribd
Upload
13 views3 pages

Levelling Notes

Levelling is a surveying technique used to measure vertical distances and determine the relative heights of points on the earth's surface, essential for construction and mapping. It involves various types such as differential and profile levelling, and utilizes instruments like dumpy levels and leveling staffs. Key concepts include benchmarks, back sights, and methods for booking and reducing levels, along with common errors and important formulas for calculations.

Uploaded by

alok kumar
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
13 views3 pages

Levelling Notes

Levelling is a surveying technique used to measure vertical distances and determine the relative heights of points on the earth's surface, essential for construction and mapping. It involves various types such as differential and profile levelling, and utilizes instruments like dumpy levels and leveling staffs. Key concepts include benchmarks, back sights, and methods for booking and reducing levels, along with common errors and important formulas for calculations.

Uploaded by

alok kumar
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
You are on page 1/ 3

Levelling (Surveying)

1. Introduction to Levelling

Levelling is a branch of surveying that deals with measuring the vertical distance of a point relative to a

datum. It is used to determine the relative heights of different points on the earth's surface.

2. Purpose of Levelling

- To determine elevations of points

- For the construction of roads, canals, railways

- For contouring and mapping

3. Types of Levelling

- Differential Levelling

- Profile Levelling

- Reciprocal Levelling

- Fly Levelling

- Precise Levelling

- Trigonometrical Levelling

4. Instruments Used in Levelling

- Dumpy Level

- Tilting Level

- Automatic Level

- Leveling Staff

5. Important Terms

- Bench Mark (BM): Fixed reference point

- Back Sight (BS): Reading on a point of known elevation

- Fore Sight (FS): Reading on a point of unknown elevation

- Intermediate Sight (IS): Between BS and FS


Levelling (Surveying)

- Height of Instrument (HI): Elevation of the line of sight

- Reduced Level (RL): Height of a point relative to the datum

6. Methods of Levelling

- Height of Instrument Method

- Rise and Fall Method

7. Booking and Reduction of Levels

Levelling observations are entered into a level book in a tabular format, followed by reduction using either HI

or Rise and Fall method.

8. Common Errors in Levelling

- Instrumental errors

- Personal errors

- Natural errors (e.g., refraction, curvature)

9. Solved Example

Example:

BS on BM = 2.345 m, IS = 1.500 m, FS = 2.900 m

BM RL = 100.000 m

HI = 100.000 + 2.345 = 102.345 m

RL of IS = 102.345 - 1.500 = 100.845 m

RL of FS = 102.345 - 2.900 = 99.445 m

10. Important Formulas

- RL = HI - Staff Reading

- HI = RL of BM + BS

- Arithmetic Check:
Levelling (Surveying)

(Sum of BS) - (Sum of FS) = Last RL - First RL

You might also like