Surveying miscellaneous
- During a levelling work along a falling gradient using a Dumpy level and a Staff of 3m length, following successive readings were taken: 1.785, 2.935, 0.360, 1.320. What will be the correct order of booking these four readings in a level book? (BS : Back Sight IS : Intermediate Sight, FS : Fore Sight)
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For first reading it is BS and then FS. Sudden change in value represent shifting of instrument. Therefore again first reading BS and then FS.
Correct Option: A
For first reading it is BS and then FS. Sudden change in value represent shifting of instrument. Therefore again first reading BS and then FS.
- Following bearings are observed while traversing with a compass.
Line Fore Bearing Back Bearing AB 126°45' 308°00' BC 49°15' 227°30' CD 340°30' 161°45' DE 258°30' 78°30' EA 212°30' 31°45'
After applying the correction due to local attraction, the corrected fore bearing of line BC will be
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The difference between back bearing and fore bearing of line DE = 258°30' – 78° 30' = 180°
∴ Station D and E are free from local attraction
Fore bearing of line EA = 212° 30'
Correct back bearing of line EA = 216° 30' – 180° = 36° 30'
∴ Error at A = 31° 45' – 36° 30' = – 4° 45'
Hence correction at A = + 4° 45'
∴ Correct fore bearing of line AB = 126°45' + 4°45'= 131° 30'
Correct back bearing of AB = 131° 30 + 180° = 311° 30'
∴ Error at B = – 3° 30'
Correction at B = + 3° 30'
Hence correct bearing of BC = 45° 15' + 3° 30' = 48° 45'Correct Option: D
The difference between back bearing and fore bearing of line DE = 258°30' – 78° 30' = 180°
∴ Station D and E are free from local attraction
Fore bearing of line EA = 212° 30'
Correct back bearing of line EA = 216° 30' – 180° = 36° 30'
∴ Error at A = 31° 45' – 36° 30' = – 4° 45'
Hence correction at A = + 4° 45'
∴ Correct fore bearing of line AB = 126°45' + 4°45'= 131° 30'
Correct back bearing of AB = 131° 30 + 180° = 311° 30'
∴ Error at B = – 3° 30'
Correction at B = + 3° 30'
Hence correct bearing of BC = 45° 15' + 3° 30' = 48° 45'
- In a leveling work, sum of the Back Sight (B.S.) and Fore Sight (F.S.) have been found to be 3.085 m and 5.645 m respectively. If the Reduced Level (R.L.) of the starting station is 100.000 m, the R.L. (in m) of the last station is ______ .
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∑BS = 3.085
∑F.S = 5.645 m
Fall = ∑FS – ∑BS
= 5.645 – 3.085 = 2.560
R.L of last station = R.L of first station – Fall
= 100 – 2.560 = 97.44 mCorrect Option: A
∑BS = 3.085
∑F.S = 5.645 m
Fall = ∑FS – ∑BS
= 5.645 – 3.085 = 2.560
R.L of last station = R.L of first station – Fall
= 100 – 2.560 = 97.44 m
- A tacheometer was placed at point P to estimate the horizontal distances PQ and PR. The corresponding stadia intercepts with the telescope kept horizontal, are 0.320 m and 0.210 m, respectively. The ∠QPR is measured to be 61° 30' 30''. If the stadia multiplication constant = 100 and stadia addition constant = 0.10 m, the horizontal distance (in m) between the points Q and R is ___________
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NA
Correct Option: A
NA
- A theodolite is set up at station A and a 3 m long staff is held vertically at station B. The depression angle reading at 2.5 m marking on the staff is 6°10'. The horizontal distance between A and B is 2200 m. Height of instrument at station A is 1.1 m and R.L. of A is 880.88 m. Apply the curvature and refraction correction, and determine the R.L. of B (in m).
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R.L. of A = 880.88 m
R.L. of Plane of Collimation = 880.88 + 1.2 = 882.08m
True staff reading at station B = 2.5 – 0.0673 × 2.22 = 2.174 m
Now, B'B'' = (tan6º 10') × 2200 = 237.701 m
R.L. of station B = R.L. of Plane of Collimation – true staff reading – B'B''
= 882.08 – 2.174 – 237.701 = 642.205 mCorrect Option: B
R.L. of A = 880.88 m
R.L. of Plane of Collimation = 880.88 + 1.2 = 882.08m
True staff reading at station B = 2.5 – 0.0673 × 2.22 = 2.174 m
Now, B'B'' = (tan6º 10') × 2200 = 237.701 m
R.L. of station B = R.L. of Plane of Collimation – true staff reading – B'B''
= 882.08 – 2.174 – 237.701 = 642.205 m