This set of Surveying Multiple Choice Questions & Answers (MCQs) focuses on “By Offsets from the Tangent”.
1. Which process can be used for setting a small curve?
a) Offsets from radial offsets
b) Offsets from perpendicular tangents
c) Bisection of arcs
d) Offsets from chords
Explanation: Even though the offset by radial and perpendicular tangents are under the same head, they are having difference in the process which makes perpendicular tangent method suitable for small curves and radial tangent method for long curve.
2. Which of the following describes the right usage of tangent method for offsets?
a) Smaller radius
b) Larger radius
c) Large deflection angle
d) More tangent length
Explanation: The tangential method can find its usage only in case of the smaller deflection angle and radius of curvature. Smaller radius of curvature enables this method to have a clear idea about setting offsets.
3. The points that are set by using the method of tangents will lie on ___________
c) Arc of circle
Explanation: The curve which is set by using the offsets produced by the tangent method involves formation of points on the parabola, but not on the arc of circle. If versine is considered then the curve will come close to the arc.
4. If the tangent distance increases, the offsets distance also increases.
Explanation: When the tangent distance increases, the offsets will become too large. It might create problem for accuracy. So, maintenance of appropriate lengths is very much needed as they are directly proportional.
5. Central position of curve can be set by _________
Explanation: Apex of the curve acts as the central position for the curve, which can be obtained by the intersection of the tangents which the touch the curve and a perpendicular can be drawn from it, which is able to determine apex distance.
6. Which of the following represents the correct set of classification in the method of setting offset by tangent method?
a) Radial, perpendicular
b) Radial, parallel
c) Parallel, perpendicular
d) Parallel, horizontal
Explanation: The method of determining offsets by the tangents method involves two classifications, radial offsets and perpendicular offsets. Each of them can be applied based on the type of work being done and their accuracy involved.
7. Find the radial offset if radius of the curve is given as 23.65m and the offset placement is at 15m.
Explanation: The formula for the radial offset can be given as
Ox = (R2 – (x)2)1/2 – R. on substitution, we get
Ox = – 23.65 + (23.652 – (15)2)1/2
Ox = -5.36m.
8. Set a radial offset by using the approximate method with radius of the curve given as 25.76m and the offset distance as 5m.
Explanation: The approximate method for finding the offsets can be determined by using the formula, Ox = x2 / 2*R. on substitution, we get
Ox = 52 / 2*25.76
Ox = 0.485m.
9. Find the perpendicular offset by using the general method, with radius of the curvature being 70.98m and the offset distance about 9m.
Explanation: The perpendicular offsets can be found out by using the formula, Ox = R-(R2 – (x)2)1/2. On substitution, we get
Ox = (70.982 – (9)2)1/2 – 70.98
Ox = -0.57m.
10. Set a perpendicular offset using the approximate method, having radius of curvature as 47.43m and the offset distance being 8m.
Explanation: The formula for finding the perpendicular offset using the approximate method can be given as Ox = x2 / 2*R. on substitution, we get
Ox = 82 / 2*47.43 = 0.67m.
Sanfoundry Global Education & Learning Series – Surveying.
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