Topics covered: Chain Surveying, Compass Surveying, Levelling
Surveying Topic-wise Questions for APSC PWD JE Exam
Topic: Chain Surveying
1. The principle of surveying is to work from:
Answer: A
The fundamental principle of surveying is to work from the whole to the part. This means establishing a framework of control points first (primary survey) and then filling in details (secondary survey) to prevent accumulation of errors.
2. The length of Gunter's chain is:
Answer: C
Gunter's chain is 66 feet long and divided into 100 links. Each link is 0.66 feet long. It was commonly used for land measurement in the imperial system.
3. The number of links in a 30m metric chain is:
Answer: B
A 30m metric chain has 150 links, with each link being 20cm long. The chain has tallies at every 5m (25 links) for easy measurement.
4. The permissible error in chaining for ordinary work is:
Answer: C
For ordinary chain surveying work, the permissible error is 1 in 1000. For more precise work, the standard is 1 in 5000.
5. The instrument used for measuring horizontal angles in chain surveying is:
Answer: D
In chain surveying, no angular measurements are taken. Only linear measurements are made using chains or tapes to determine relative positions of points.
6. The correction for sag in chain surveying is always:
Answer: B
Sag correction is always negative because the actual measured length is more than the horizontal distance due to the sagging of the chain or tape between supports.
7. The best shape of a triangle in chain surveying is:
Answer: A
An equilateral triangle is considered the best shape in chain surveying because it provides the strongest network with minimum error propagation when plotting.
8. The limiting length of an offset is when its direction error exceeds:
Answer: C
The limiting length of an offset is reached when the probable displacement due to direction error exceeds 15°. Beyond this, the offset becomes unreliable.
9. The correction for temperature in chain surveying is given by:
Answer: A
Temperature correction formula is C = α(T₂-T₁)L, where α is coefficient of thermal expansion, T₂ is field temperature, T₁ is standardization temperature, and L is measured length.
10. The instrument used for running a straight line between two points is:
Answer: D
A line ranger is used to establish intermediate points on a straight line between two end points. It consists of two mirrors or prisms at 45° to the line of sight.
Topic: Compass Surveying
11. The magnetic bearing of a line is 48°24'. If the magnetic declination is 5°38' West, the true bearing is:
Answer: A
True Bearing = Magnetic Bearing - Westerly Declination = 48°24' - 5°38' = 42°46'. West declination is subtracted from magnetic bearing to get true bearing.
12. The angle between the magnetic meridian and the true meridian is called:
Answer: B
Magnetic declination is the angle between the magnetic meridian (direction shown by compass needle) and true meridian (geographic north-south line). It varies with location and time.
13. The temporary adjustments of a prismatic compass include:
Answer: C
Temporary adjustments of prismatic compass include: (1) Centering over station point, (2) Leveling using ball and socket arrangement, and (3) Focusing the prism for clear reading.
14. The horizontal angle between the forward direction of survey line and the reference meridian is called:
Answer: C
Bearing is the horizontal angle between the reference meridian (true or magnetic) and the survey line, measured clockwise from the north direction.
15. The dip of the magnetic needle is maximum at:
Answer: C
Magnetic dip (inclination) is maximum (90°) at magnetic poles where the magnetic field lines are vertical. At the equator, dip is 0° (needle remains horizontal).
16. The type of bearing measured clockwise from the preceding line to the following line is called:
Answer: D
A deflection angle is the angle between the prolongation of the preceding line and the following line, measured clockwise (right) or counter-clockwise (left).
17. The error in compass surveying due to local attraction can be detected by:
Answer: B
Local attraction is detected when the difference between fore bearing and back bearing of a line is not exactly 180°. The correct difference should be 180° in absence of local attraction.
18. The instrument used to measure the magnetic bearing of a line is:
Answer: C
A prismatic compass is used to measure magnetic bearings of survey lines. It consists of a magnetic needle, graduated circle, and a prism for reading bearings directly.
19. The bearing of a line AB is 150°15'. Its whole circle bearing is:
Answer: B
150°15' in whole circle bearing is equivalent to S 29°45' E in reduced bearing (quadrantal bearing). It lies in SE quadrant (180°-150°15' = 29°45').
20. The angle between two successive compass bearings is called:
Answer: B
Included angle is the interior angle between two successive survey lines in a traverse. It can be calculated from the difference of their bearings.
Topic: Levelling
21. The principle of levelling is based on:
Answer: B
Levelling is based on establishing a horizontal line of sight. The level instrument provides this reference line, and staff readings are taken to determine elevation differences.
22. The sensitivity of a bubble tube depends on:
Answer: D
Bubble tube sensitivity depends on: (1) Length - longer tubes are more sensitive, (2) Radius of curvature - larger radius increases sensitivity, (3) Liquid viscosity - affects bubble movement.
23. The correction for curvature in levelling is given by:
Answer: A
Correction for curvature (Cc) = 0.0673 D² meters, where D is distance in kilometers. Earth's curvature makes points appear lower than they actually are.
24. The combined correction for curvature and refraction is:
Answer: A
Combined correction = Cc - Cr = 0.0673D² - (1/7 × 0.0673D²) = 0.0573D² meters (where D is in km). Refraction correction is about 1/7th of curvature correction.
25. The temporary adjustments of a dumpy level include:
Answer: C
Temporary adjustments of dumpy level are: (1) Setting up the instrument on tripod, (2) Leveling using foot screws, and (3) Focusing to eliminate parallax.
26. The difference between backsight and foresight at a change point is equal to:
Answer: A
Difference between consecutive backsight and foresight gives the rise or fall between points. If BS > FS = Rise, if FS > BS = Fall.
27. The type of levelling used for establishing benchmarks over a wide area is:
Answer: C
Precise levelling is used for establishing benchmarks with high accuracy. It uses special precise levels, invar staves, and careful observation techniques to minimize errors.
28. The permissible closing error in ordinary levelling is:
Answer: B
Permissible error in ordinary levelling is 10√K mm, where K is circuit length in km. For precise levelling, it's 3√K mm or less.
29. The collimation error in levelling can be eliminated by:
Answer: A
Collimation error (line of sight not horizontal) is eliminated by keeping backsight and foresight distances equal at each setup. The errors cancel out in the elevation difference.
30. The staff reading taken on a point of known elevation is called:
Answer: A
Backsight is the first reading taken after setting up the instrument, usually on a benchmark or point of known elevation to determine the height of instrument (HI).