Surveying – Main Divisions (Plane Surveying & Geodetic Surveying)

Surveying – Main Divisions (Plane Surveying & Geodetic Surveying)

Surveying is broadly divided into two main categories based on the consideration of the earth’s curvature: Plane Surveying and Geodetic Surveying. In ITI Draughtsman Civil, understanding these two divisions is essential for selecting the appropriate method of survey for different engineering projects.

1. Plane Surveying

Plane surveying is the method of surveying in which the curvature of the earth is neglected, and the surface of the earth is assumed to be flat. It is suitable for small areas where high precision is not required.

Features of Plane Surveying

• The earth’s surface is considered as a plane.
• Lines are treated as straight and parallel.
• Angles are assumed to be plane angles.
• Used for small-scale surveys.

Methods Used in Plane Surveying

• Chain Survey
• Compass Survey
• Plane Table Survey
• Levelling
• Theodolite Survey (for moderate accuracy)

Applications of Plane Surveying

• Preparation of small-scale maps.
• Survey of building sites.
• Road and canal alignment.
• Land measurement and plotting.

Advantages of Plane Surveying

• Simple and easy to perform.
• Less time-consuming.
• Economical method.

Limitations of Plane Surveying

• Not suitable for large areas.
• Less accurate compared to geodetic surveying.

2. Geodetic Surveying

Geodetic surveying is the method in which the curvature of the earth is taken into account. It is used for large areas and requires high accuracy.

Features of Geodetic Surveying

• Considers the earth as a spheroid.
• Lines are curved due to earth’s curvature.
• Uses spherical trigonometry.
• Highly precise and accurate.

Methods Used in Geodetic Surveying

• Triangulation
• Trilateration
• Precise levelling
• Satellite-based surveying (GPS)

Applications of Geodetic Surveying

• Survey of large areas such as countries and states.
• Preparation of topographical maps.
• Establishment of control points.
• Scientific and research purposes.

Advantages of Geodetic Surveying

• High accuracy and precision.
• Suitable for large-scale projects.

Limitations of Geodetic Surveying

• Complex and time-consuming.
• Requires skilled personnel and advanced instruments.
• More expensive.

3. Difference Between Plane and Geodetic Surveying

4. Importance of Classification

The division of surveying into plane and geodetic helps engineers choose the correct method based on the size of the area and accuracy required. It ensures efficient and reliable survey work.

Role of Draughtsman Civil

A Draughtsman Civil uses survey data to prepare plans and maps. Understanding the difference between plane and geodetic surveying helps in interpreting data correctly and applying it in construction drawings.

Conclusion

Surveying is mainly divided into plane surveying and geodetic surveying. Plane surveying is suitable for small areas and is simple, while geodetic surveying is used for large areas and provides high accuracy.

For ITI Draughtsman Civil students, knowledge of these main divisions is essential for selecting appropriate surveying methods and ensuring accurate construction planning.