Short Answer:
Chain surveying is a simple method of land measurement where distances are measured using a chain or tape, and angles are determined by sighting along straight lines. It is best suited for small areas with clear and even ground. Chain surveying is commonly used in plot measurement, small land surveys, and road construction planning. It is easy to perform and requires minimal equipment, making it useful for preliminary surveys before detailed measurements are taken.
Detailed Explanation:
Chain surveying is one of the oldest and simplest methods of surveying used for measuring distances and creating maps of small areas. It is based on linear measurements, meaning only distances between points are recorded, and no advanced instruments are used to measure angles or heights.
Principle of Chain Surveying:
- The land is divided into triangles for easy measurement.
- A chain or measuring tape is used to measure distances between points.
- Ranging rods and arrows help in marking survey points and aligning straight lines.
- A field book is used to record measurements and sketch the area being surveyed.
Instruments Used in Chain Surveying:
- Surveying Chain: A metallic chain (e.g., Gunter’s chain or Engineer’s chain) used to measure distances.
- Tape Measure: A flexible tape used when greater accuracy is required.
- Ranging Rods: Tall poles used to mark straight lines and survey points.
- Arrows: Small metal pins placed in the ground to indicate measured points.
- Plumb Bob: Helps in ensuring vertical alignment while measuring distances.
Where Chain Surveying is Used:
- Small Land Surveys: Used for measuring plots of land, farms, and residential areas.
- Road and Railway Projects: Helps in planning straight sections of roads and tracks.
- Field Mapping: Used in topographic surveys to create rough sketches of an area.
- Boundary Surveys: Determines land ownership and property lines.
- Preliminary Construction Work: Helps in initial site planning before detailed measurements are taken.
Advantages of Chain Surveying:
- Simple and easy to use, requiring minimal equipment.
- Suitable for small, open areas with relatively flat terrain.
- Provides quick results without complex calculations.
Disadvantages of Chain Surveying:
- Not suitable for large or hilly areas.
- Errors can occur due to human mistakes and uneven ground.
- Weather conditions like wind and temperature changes can affect measurements.
Conclusion:
Chain surveying is a basic and effective method for measuring small land areas using simple tools like chains and tapes. It is widely used for plot measurement, road planning, and preliminary surveys where high precision is not required. Despite its limitations, it remains a valuable technique in civil engineering for quick and straightforward land measurement.