An angle made by a survey line with the prolongation of the proceeding line, is known as

Explanation:

Deflection Angle

Definition: A deflection angle is the angle formed by a survey line with the prolongation (or extension) of the preceding survey line. It is measured either to the right or left of the prolongation of the previous line. This type of angle is crucial in surveying and is generally used in route surveying, such as for roads, railways, or pipelines, where changes in direction occur along the path.

Working Principle: In surveying, to determine the direction of a new line concerning the previously established line, the deflection angle is measured. This angle can be either clockwise (right) or counterclockwise (left), and it helps surveyors establish accurate alignments and ensure that the project layout is consistent with the intended design.

Measurement: A deflection angle is measured using a theodolite or a total station instrument. The prolongation of the preceding survey line is extended, and the angle between this prolongation and the new line is measured.

Types of Deflection Angles:

• Right Deflection Angle: If the new line deviates to the right of the prolongation of the previous line, the angle is termed a right deflection angle.
• Left Deflection Angle: If the new line deviates to the left of the prolongation of the previous line, the angle is termed a left deflection angle.

Importance in Surveying:

• Deflection angles are critical for setting out curves and ensuring the alignment of structures such as roads and railways.
• They help in avoiding obstacles and ensuring that the layout follows the design plan.
• Accurate measurement of deflection angles ensures that there are no errors in the alignment of successive survey lines.