____ is the method used when the ground is unsuitable for chaining and...
Two Theodolite Method:
- This method is very useful in the absence of a chain or tape and also when the ground is not favorable for accurate chaining.
- In this method, the property of the circle 'that the angle between the tangent and the chord equals the angle which that chord subtends in the opposite segment' is used.
- This is a simple and accurate method of setting out the curve.
- It requires two instruments and two surveyors to operate upon them, so it is not as commonly used as the method of deflection angles.
Tachometric Method:
- In this method, the horizontal and vertical positions of points on the earth's surface relative to one another are determined without using a chain or tape, or a separate leveling instrument.
Rankine’s Method of Tangential or Deflection Angles:
- In this method, the curve is set out by the tangential angles (also known as deflection angles) with a theodolite and a chain or a tape.
- The method is also called as chain and theodolite method.
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____ is the method used when the ground is unsuitable for chaining and...
Understanding the Two Theodolite Method
The Two Theodolite Method is particularly useful in surveying when the ground is unsuitable for chaining, such as in hilly terrains or uneven surfaces. This method leverages the geometric relationship between angles and distances.
Principle Behind the Method
- The Two Theodolite Method relies on the principle that the angle between the tangent and the chord of a curve is equal to the angle subtended by that chord in the opposite segment.
- By utilizing two theodolites placed at different positions, surveyors can accurately determine horizontal angles and distances without needing a continuous chain line.
Procedure
1. Setup Two Theodolites: Place one theodolite at each end of the line to be surveyed.
2. Measure Angles: Use the two instruments to measure the angles subtended at each theodolite.
3. Calculate Distances: Employ trigonometric relationships to calculate the distances based on the measured angles, providing a more accurate representation of the terrain.
Advantages of the Two Theodolite Method
- Accuracy: This method minimizes errors that can arise from chaining on uneven ground.
- Flexibility: It can be applied in various terrains where conventional chaining is impractical.
- Efficiency: Reduces the need for intermediate points, streamlining the surveying process.
Conclusion
The Two Theodolite Method is an effective surveying technique that ensures accurate measurements in challenging terrains. By understanding and applying this method, civil engineers can enhance the reliability of their surveying projects.