Surveying miscellaneous
- The following table gives data of consecutive co-ordinates in respect of a closed theodolite traverse PQRSP.
The magnitude and direction of error of closure in whole circle bearing are
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∑L = 400.75 + 100.25 – 199 – 300 = 2
∑D = – 300.5 + 199.25 + 399.75 – 200.5 = – 2
Error of closure = √(∑C)² + (∑D)² = √4 + 4 = 2√2tan θ = ∑D = - 1 ∑L
∴ θ = 315°
Correct Option: C
∑L = 400.75 + 100.25 – 199 – 300 = 2
∑D = – 300.5 + 199.25 + 399.75 – 200.5 = – 2
Error of closure = √(∑C)² + (∑D)² = √4 + 4 = 2√2tan θ = ∑D = - 1 ∑L
∴ θ = 315°
- The magnetic bearing of a line AB is S 45° E and the declination is 5° West. The true bearing of the line AB is
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SE – therefore 2nd quadrant
True bearing = S 40° E.Correct Option: B
SE – therefore 2nd quadrant
True bearing = S 40° E.
- The length and bearings of a closed traverse PQRSP are given below.
The missing length and bearing, respectively of the line SP are
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For closed traverse in WCB,
Sum of latitude, ∑L cos θ = 0 and sum of departure ∑L sin θ = 0.
∑L cos θ = 200 cos 0° + 1000 cos 45° + 907 cos 180° + x cos θ = 0
∴ x cos θ = – 0.1068°
∑L sin θ = 0 = 200 sin 0° + 1000 sin 45° + 907 sin 180° + x sin θ = 0
∴ x sin θ = – 707.11
∴ from both equation, θ = 270°
x = 707.1068 mCorrect Option: B
For closed traverse in WCB,
Sum of latitude, ∑L cos θ = 0 and sum of departure ∑L sin θ = 0.
∑L cos θ = 200 cos 0° + 1000 cos 45° + 907 cos 180° + x cos θ = 0
∴ x cos θ = – 0.1068°
∑L sin θ = 0 = 200 sin 0° + 1000 sin 45° + 907 sin 180° + x sin θ = 0
∴ x sin θ = – 707.11
∴ from both equation, θ = 270°
x = 707.1068 m
- The plan of a survey plotted to a scale of 10 m to 1 cm is reduced in such a way that a line originally 10 cm long now measures 9 cm. The area of the reduced plan is measured as 81 cm2. The actual (m2) of the survey is
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Actual area = Actual scale 2 × measured area × scale Reduced scale = 100 × 81 × 100 = 10000 m2 81 Correct Option: A
Actual area = Actual scale 2 × measured area × scale Reduced scale = 100 × 81 × 100 = 10000 m2 81
- The observed magnetic bearing of a line OE was found to be 185°. It was later discovered that station O had a local attraction of + 1.5°. The true bearing of the line OE, considering a magnetic declination of 3.5° E shall be
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Corrected magnetic bearing = measured value – Local attraction
= 185 – 1.5 = 183.5°
True bearing = magnetic bearing + magnetic declination
= 183.5 + 3.5 = 187°Correct Option: B
Corrected magnetic bearing = measured value – Local attraction
= 185 – 1.5 = 183.5°
True bearing = magnetic bearing + magnetic declination
= 183.5 + 3.5 = 187°