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Examoogle • User • info@examoogle.com • EE-2024-8821
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What is said to when survey line makes with the prolongation of the preceding line?
Horizontal angle
Vertical angle
Deflection angle
Pont of intersection
Deflection angle
A deflection angle is the angle between a survey line and the prolongation (extension) of the preceding survey line. It indicates how much the new line turns away from the direct path of the previous line.
A deflection angle is the angle between a survey line and the prolongation (extension) of the preceding survey line. It indicates how much the new line turns away from the direct path of the previous line.
δ=∣Included Angle−180°∣ — relationship between included angle and deflection angle
Right Deflection=Forward Azimuth - Back Azimuth—calculation from bearings
In traversing with a theodolite, the instrument is set up at a station and back-sighted along the previous line. The telescope is then inverted (plunged) to point along the prolongation of that line, and swung horizontally to sight the forward station to measure the angle turned.
Deflection angles vary from 0° to 180° and are designated as Right (clock-wise) or Left (counter-clockwise).
Widely used in open traverses for continuous linear surveys such as roads, railways, pipelines, and canals.
For a closed traverse with N sides, the algebraic sum of deflection angles equals 360° (Right angles taken as positive, Left as negative).
Simplifies field notes and layout procedures for long linear route surveying.
Directly provides the turning angle needed for setting up circular curves.
Instrument errors (like collimation error) double if the telescope is plunged without double centering.
Errors can accumulate sequentially along an open traverse if not checked regularly.
Highway and railway alignment surveys.
Pipeline, canal, and transmission line surveys.
Option A (Horizontal angle): General term for any angle measured in a horizontal plane between two lines.
Option B (Vertical angle): The angle measured in a vertical plane between the line of sight and the horizontal plane.
Option D (Point of intersection): The vertex point where two straight tangents of a curve intersect.
C is correct — The deflection angle is explicitly defined as the angle made by a survey line with the extended prolongation of the preceding survey line.
Remember for curve design: the deflection angle between the initial tangent and final tangent equals the total central angle (Δ) subtended by the circular curve at its center.