Top 100 Interview Questions on Plane Table Surveying

Introduction

Welcome, aspiring surveyors! If you’re gearing up for a Plane Table Surveying interview, you’ve come to the right place. In this guide, we’ll delve into the Top 50 Interview Questions on Plane Table Surveying, providing you with insights, tips, and everything you need to nail that interview.

1. What is Plane Table Surveying?

   • Answer: Plane Table Surveying is a graphical method of surveying in which the field observations and plotting are done simultaneously in the field.

2. What is a plane table?

   • Answer: A plane table is a drawing board mounted on a tripod that can be leveled. It has an alidade with a sight vane for sighting the survey stations.

3. Explain the principle of Plane Table Surveying.

   • Answer: The principle involves the direct observation and plotting of survey details on a plane table in the field. It eliminates the need for field notes and allows for real-time mapping.

4. What is a back sighting in Plane Table Surveying?

   • Answer: Backsighting is the process of sighting back to a point whose position is already known. It helps in maintaining the accuracy of the survey.

5. What is Traversing in Plane Table Surveying?

   • Answer: Traversing is the process of surveying a series of connected points in a sequence to determine their relative positions.

6. Explain Radiation in Plane Table Surveying.

   • Answer: Radiation is the process of drawing rays from a single known point to locate other points on the plane table.

7. What is Resection in Plane Table Surveying?

   • Answer: Resection is the process of determining the position of the plane table station by sighting back to two or more known points.

8. Why is a plane table always leveled before starting a survey?

   • Answer: Leveling the plane table ensures that the plotted points are accurate and eliminates errors caused by the table not being level.

9. What is meant by the term “orienting” in Plane Table Surveying?

   • Answer: Orienting refers to the process of setting the plane table in such a way that its plane is parallel to the ground surface.

10. Explain the difference between a fore bearing and a back bearing.

    • Answer: A fore bearing is the direction of a line measured in the direction of survey, while a back bearing is measured in the opposite direction.

11. What is the purpose of a fiducial mark on a plane table?

    • Answer: A fiducial mark is used to establish a reference direction for plotting and sighting. It is often placed on the rim of the alidade.

12. How is a magnetic meridian related to Plane Table Surveying?

    • Answer: The magnetic meridian is used in Plane Table Surveying to correct the observed directions for magnetic declination.

13. Explain the concept of magnetic declination.

    • Answer: Magnetic declination is the angle between the magnetic meridian and the true meridian at a specific location. It is used for correcting magnetic bearings.

14. What are the advantages of Plane Table Surveying?

    • Answer: Advantages include real-time plotting, simplicity, and the ability to visualize the survey area in the field.

15. How is the scale of a map determined in Plane Table Surveying?

    • Answer: The scale is determined by the distance between the plane table station and the paper, known as the “plane table to paper distance.”

16. What is a “lost station” in Plane Table Surveying?

    • Answer: A lost station is a point whose position cannot be determined by direct observation due to obstacles. It requires additional methods like resection.

17. Explain the purpose of a survey traverse in Plane Table Surveying.

    • Answer: A traverse helps in connecting and determining the relative positions of different survey stations.

18. What are the limitations of Plane Table Surveying?

    • Answer: Limitations include the inability to survey large areas efficiently, susceptibility to errors due to instrument setup, and the need for skilled personnel.

19. What is meant by “meridian convergence” in Plane Table Surveying?

    • Answer: Meridian convergence is the angle between the magnetic meridian and the true meridian, which varies with location.

20. How is a closed traverse different from an open traverse in Plane Table Surveying?

    • Answer: A closed traverse is a series of connected survey lines forming a closed figure, while an open traverse does not close upon itself.

21. Explain the procedure for plotting a point using radiation in Plane Table Surveying.

    • Answer: The alidade is sighted to a known point, and rays are drawn from that point to the desired point. Where the rays intersect is the plotted location.

22. What is a “station mark” in Plane Table Surveying?

    • Answer: A station mark is a point on the ground where the plane table is set up for surveying. It should be easily identifiable and have a known position.

23. How is a topographic map created using Plane Table Surveying?

    • Answer: Contour lines are drawn based on elevation data collected during the survey to represent the terrain’s relief.

24. Explain the role of an alidade in Plane Table Surveying.

    • Answer: The alidade is used for sighting and measuring angles. It has a sight vane for aiming at survey stations and an index arm for measuring angles.

25. What is the purpose of a “hinge pin” in the alidade of a plane table?

    • Answer: The hinge pin allows the alidade to rotate and change its direction during surveying.

26. How does the selection of a fiducial mark affect the accuracy of a Plane Table Survey?

    • Answer: A well-chosen fiducial mark improves the accuracy of the survey by providing a stable reference direction.

27. What is the significance of the “two-point problem” in Plane Table Surveying?

    • Answer: The two-point problem refers to the situation where two known points are visible from the plane table station, and the surveyor must decide which one to use as a reference.

28. Explain the concept of “closure error” in a traverse.

    • Answer: Closure error is the algebraic sum of the differences between the measured and calculated values in a closed traverse. It indicates the precision of the survey.

29. How does the curvature of the Earth affect Plane Table Surveying?

    • Answer: For long survey lines, the curvature of the Earth must be considered to correct the observed directions and distances.

30. What is the purpose of “radiation tables” in Plane Table Surveying?

    • Answer: Radiation tables provide pre-calculated values for the distances and angles in the radiation process, saving time during the survey.

31. How does atmospheric refraction affect the accuracy of Plane Table Surveying?

    • Answer: Atmospheric refraction can cause errors in sighting, especially near sunrise and sunset, and corrections may be needed.

32. Explain the concept of “triangulation” in Plane Table Surveying.

    • Answer: Triangulation is the process of surveying by measuring the angles of a triangle formed by three survey stations. It is used for accurate mapping of large areas.

33. What is the purpose of a “drawing sheet” in Plane Table Surveying?

    • Answer: The drawing sheet is the paper on the plane table where the survey details are plotted. It serves as the map or plan of the surveyed area.

34. How is a magnetic needle used in Plane Table Surveying?

    • Answer: A magnetic needle is used to establish the magnetic meridian, which is then used to correct magnetic bearings during the survey.

35. What precautions should be taken during the leveling of a plane table?

    • Answer: The table should be leveled carefully using the leveling screws, and the bubble in the spirit level should be centered.

36. Explain the process of “reciprocal leveling” in Plane Table Surveying.

    • Answer: Reciprocal leveling involves checking the level of the plane table by leveling it in two opposite directions and ensuring that both readings are the same.

37. How can the accuracy of a Plane Table Survey be improved?

    • Answer: Accurate leveling, careful sighting, proper fiducial mark selection, and the use of radiation tables are some ways to improve accuracy.

38. What is meant by the “accuracy ratio” in Plane Table Surveying?

    • Answer: The accuracy ratio is the ratio of the horizontal distance between the plane table station and a plotted point to the corresponding ground distance.

39. What are the factors affecting the selection of a fiducial mark in Plane Table Surveying?

    • Answer: Visibility, stability, and ease of identification are important factors in selecting a fiducial mark.

40. How is the magnetic declination determined in the field during a Plane Table Survey?

    • Answer: The magnetic declination can be obtained from a magnetic declination chart or by using a magnetic compass.

41. What is the significance of contour lines in a Plane Table Survey?

    • Answer: Contour lines represent lines of equal elevation on the map and help in visualizing the topography of the surveyed area.

42. Explain the concept of “radial plotting” in Plane Table Surveying.

    • Answer: Radial plotting involves drawing rays from the plane table station to the plotted points, and the intersection of these rays gives the positions of the points.

43. How can errors due to magnetic disturbances be minimized in Plane Table Surveying?

    • Answer: Avoiding ferrous objects, using a non-magnetic alidade, and taking magnetic readings away from magnetic disturbances can minimize errors.

44. What is the purpose of “trial sketches” in Plane Table Surveying?

    • Answer: Trial sketches are preliminary sketches made during the survey to check the accuracy of the plotted details.

45. Explain the concept of “interior orientation” in Plane Table Surveying.

    • Answer: Interior orientation involves determining the position of the plane table station with respect to the plotted points on the map.

46. How can errors due to atmospheric conditions be minimized in Plane Table Surveying?

    • Answer: Taking readings during stable atmospheric conditions, avoiding extreme temperatures, and using proper surveying techniques can minimize errors.

47. What is the role of “accuracy checks” in a Plane Table Survey?

    • Answer: Accuracy checks involve verifying the measured and calculated values during the survey to ensure the reliability of the results.

48. Explain the concept of “closing error” in Plane Table Surveying.

    • Answer: Closing error is the discrepancy between the first and last survey points in a traverse, and it indicates the overall precision of the survey.

49. What are the common sources of errors in Plane Table Surveying?

    • Answer: Errors can arise from instrument inaccuracies, improper leveling, sighting errors, atmospheric conditions, and inadequate fiducial mark selection.

50. How can a Plane Table Survey be extended to cover a large area?

    • Answer: By connecting adjacent surveys through common points, establishing control points, and using a systematic approach, Plane Table Surveying can be extended to cover larger areas.

51. What is the purpose of “offsetting” in Plane Table Surveying?

• Answer: Offsetting involves measuring perpendicular distances from a surveyed line to locate features or details that are not directly accessible.

52. Explain the term “collimation” in the context of Plane Table Surveying.

• Answer: Collimation is the process of aligning the line of sight of the alidade with a reference line, ensuring accurate sighting during the survey.

53. How is a Plane Table Survey affected by terrain irregularities?

• Answer: Terrain irregularities can impact visibility and the ability to establish direct lines of sight, requiring additional methods like triangulation or traversing.

54. What is the role of a “sighting vane” on the alidade?

• Answer: The sighting vane is used to aim at the survey stations. It is an essential part of the alidade for accurate sighting during the survey.

55. Explain the significance of “forward and backward sighting” in Plane Table Surveying.

• Answer: Forward sighting involves sighting from the instrument to a target, while backward sighting involves sighting from the target to the instrument. Both are crucial for accurate measurements.

56. How can a plane table be protected from adverse weather conditions during a survey?

• Answer: Using a rain cover or tent can protect the plane table and drawing sheet from rain or wind, ensuring the survey is not affected by adverse weather.

57. What is the purpose of a “radial line” in Plane Table Surveying?

• Answer: A radial line is a line drawn from the station through a surveyed point to facilitate accurate plotting and location determination.

58. Explain the concept of “folding the plane table” during a survey.

• Answer: Folding the plane table involves closing the alidade and securing the instrument when not in use, protecting it from damage during transportation.

59. What is the importance of “checking angles” during a Plane Table Survey?

• Answer: Checking angles ensures the accuracy of the measured angles and helps identify any instrument or observational errors.

60. How is “radiation surveying” different from other surveying methods?

• Answer: Radiation surveying is unique to Plane Table Surveying, involving drawing rays from a known point to locate other points directly on the field.

61. What precautions should be taken when using a magnetic compass in Plane Table Surveying?

• Answer: Avoiding nearby magnetic objects and ensuring the compass is level are important precautions to minimize errors in magnetic readings.

62. Explain the term “free station” in the context of Plane Table Surveying.

• Answer: A free station is a point chosen in the field without regard to its known position, and its coordinates are determined during the survey.

63. How can the accuracy of distance measurement be improved in Plane Table Surveying?

• Answer: Using a stadia rod, measuring distances in flat terrain, and avoiding slopes can improve the accuracy of distance measurements.

64. What is the purpose of “running a checkline” in Plane Table Surveying?

• Answer: Running a checkline involves sighting back to a known point from a plotted point, ensuring the accuracy of the survey.

65. Explain the concept of “line of collimation” in Plane Table Surveying.

• Answer: The line of collimation is an imaginary line passing through the sighting vane and the fiducial mark, ensuring accurate sighting during the survey.

66. How can a Plane Table Survey be adjusted for scale distortion?

• Answer: A scale factor can be applied to correct for scale distortion, ensuring that the plotted distances accurately represent the ground distances.

67. What is the significance of “staking out” in Plane Table Surveying?

• Answer: Staking out involves physically marking the ground positions of surveyed points, providing reference points for construction or further activities.

68. How does the selection of contour intervals affect the representation of terrain on a map?

• Answer: Smaller contour intervals provide more detailed representations of terrain features, while larger intervals result in more generalized maps.

69. What is the role of “subsidiary stations” in Plane Table Surveying?

• Answer: Subsidiary stations are additional survey points established to improve the accuracy and reliability of the survey.

70. How can the accuracy of angular measurements be improved in Plane Table Surveying?

• Answer: Using a theodolite or a theodolite attachment, and ensuring proper leveling and collimation, can improve the accuracy of angular measurements.

71. Explain the term “composite error” in the context of Plane Table Surveying.

• Answer: Composite error is the combined effect of various errors in surveying, including instrument errors, observational errors, and atmospheric errors.

72. What precautions should be taken to avoid errors due to poor illumination during a Plane Table Survey?

• Answer: Adequate lighting, using reflective materials, and avoiding surveys during low-light conditions can minimize errors due to poor illumination.

73. How is “closure” achieved in a Plane Table Survey traverse?

• Answer: Closure is achieved by comparing the first and last surveyed points, adjusting measurements or angles if necessary to minimize any closure error.

74. What is the purpose of “anchoring” the plane table during a survey?

• Answer: Anchoring involves securing the plane table to the ground or a stable platform, preventing movement that could introduce errors during the survey.

75. Explain the concept of “visual intersection” in Plane Table Surveying.

• Answer: Visual intersection involves locating a point by intersecting lines of sight from two or more survey stations, providing redundancy and improving accuracy.

76. What is the purpose of “reduction to the meridian” in Plane Table Surveying?

• Answer: Reduction to the meridian involves correcting the observed angles for the local meridian, ensuring accurate representation on the map.

77. Explain the significance of “perspective center” in Plane Table Surveying.

• Answer: The perspective center is a point on the drawing sheet directly above the station on the ground. It helps maintain accuracy in the plotted details.

78. How can a Plane Table Survey be adapted for underground mapping or confined spaces?

• Answer: Using auxiliary instruments like mirrors, prisms, or extensions can allow for surveying in confined spaces or underground environments.

79. What is the role of a “parallel rule” in Plane Table Surveying?

• Answer: A parallel rule is used to transfer lines and distances accurately from one part of the drawing sheet to another, aiding in the map preparation.

80. Explain the concept of “reflected ray plotting” in Plane Table Surveying.

• Answer: Reflected ray plotting involves using a mirror to reflect the image of the fiducial mark, facilitating accurate orientation of the plane table.

81. How does Plane Table Surveying differ from Total Station Surveying?

• Answer: Plane Table Surveying involves real-time plotting in the field, while Total Station Surveying typically relies on electronic instruments for data collection and post-processing.

82. What challenges are associated with surveying in densely vegetated areas using Plane Table Surveying?

• Answer: Vegetation can obstruct visibility, and additional efforts may be required to clear sightlines or use alternative surveying methods.

83. Explain the purpose of “sketch mapping” in the initial stages of a Plane Table Survey.

• Answer: Sketch mapping involves creating rough outlines of the surveyed area, helping to plan the survey and identify key features.

84. How can the effects of “scale distortion” be minimized in Plane Table Surveying?

• Answer: Choosing an appropriate plane table to paper distance and applying a scale factor can help minimize scale distortion.

85. What precautions should be taken when conducting a Plane Table Survey near power lines or electrical equipment?

• Answer: Maintaining a safe distance, avoiding metal instruments, and using non-magnetic materials can minimize errors near power lines.

86. Explain the significance of “ground control points” in Plane Table Surveying.

• Answer: Ground control points are known, accurately surveyed points used to georeference the Plane Table Survey data to a coordinate system.

87. What role does “map orientation” play in Plane Table Surveying?

• Answer: Map orientation involves aligning the map with the true or magnetic north, providing a reference for accurate plotting.

88. How can Plane Table Surveying be used for environmental monitoring?

• Answer: Plane Table Surveying can be employed to monitor changes in land cover, vegetation, and other environmental factors over time.

89. Explain the concept of “continuous traverse” in Plane Table Surveying.

• Answer: Continuous traverse involves surveying continuously from one point to the next without closing the traverse until the entire area is covered.

90. What is the purpose of “contour interpolation” in Plane Table Surveying?

• Answer: Contour interpolation involves estimating contour lines between surveyed points to create a more detailed representation of the terrain.

91. How can Plane Table Surveying be applied in urban planning and development?

• Answer: It can be used to map existing infrastructure, plan new developments, and assess the impact of proposed changes on the urban landscape.

92. Explain the concept of “photogrammetric Plane Table Surveying.”

• Answer: Photogrammetric Plane Table Surveying involves integrating aerial photographs with ground survey data to create detailed maps.

93. What are the advantages of using Plane Table Surveying for cadastral mapping?

• Answer: Real-time plotting allows for immediate verification of property boundaries, reducing the likelihood of errors in cadastral mapping.

94. How can Plane Table Surveying be adapted for use in archaeological site mapping?

• Answer: It can be employed to create detailed maps of archaeological sites, recording the location and layout of artifacts and features.

95. What is the role of “scale determination” in Plane Table Surveying?

• Answer: Scale determination involves choosing an appropriate scale for the map based on the size and extent of the surveyed area.

96. Explain the significance of “terrain analysis” in Plane Table Surveying.

• Answer: Terrain analysis involves studying the topography to identify natural features, drainage patterns, and potential areas of concern.

97. How can Plane Table Surveying contribute to disaster management and response?

• Answer: It can be used to quickly assess and map the extent of damage after a disaster, aiding in efficient response and recovery efforts.

98. What is the role of “aerial triangulation” in conjunction with Plane Table Surveying?

• Answer: Aerial triangulation involves determining the position of ground points using overlapping aerial photographs, improving the accuracy of Plane Table Survey data.

99. How does Plane Table Surveying handle irregularly shaped survey areas?

• Answer: Irregularly shaped areas can be surveyed by adapting the traverse or triangulation methods to cover the entire extent.

100. What advancements in technology have influenced Plane Table Surveying in recent years? – Answer: Integration with GPS technology, digital mapping software, and the use of unmanned aerial vehicles (UAVs) have significantly influenced the field of Plane Table Surveying.