Surveying Top 100 One-Linear/Latest interview Questions & Answers
Surveying Top 100 One-Linear/Latest interview Questions & Answers:
Fundamentals of Surveying
NTSQA0001
Question: What is the main guiding principle of surveying?
Answer: Working from whole to part.
NTSQA0002
Question: What is the primary purpose of the "working from whole to part" principle?
Answer: To prevent the accumulation of errors and localize them.
NTSQA0003
Question: At what area limit is Plane Surveying generally conducted?
Answer: When the area is less than $195.5 \text{ km}^2$.
NTSQA0004
Question: What is the distinguishing factor of Geodetic Surveying?
Answer: The curvature of the Earth is taken into account for measurements.
NTSQA0005
Question: What are the fundamental units of measurement in surveying?
Answer: Length, Angle, Time, and Mass.
NTSQA0006
Question: Define Representative Fraction (RF).
Answer: It is the ratio of map distance to ground distance, expressed as a fraction (e.g., 1/1000).
NTSQA0007
Question: What is a "Great Circle" on Earth?
Answer: It is the largest possible circle that can be drawn on the Earth's surface, passing through the center of the Earth.
NTSQA0008
Question: What is the direction of a Plumb Line?
Answer: It is normal to the force of gravity and perpendicular to the level surface at any point.
Chain & Tape Surveying
NTSQA0009
Question: What is the standard length and link count of an Engineering Chain?
Answer: 100 feet in length with 100 links.
NTSQA0010
Question: What is the length of a Gunter’s Chain?
Answer: 66 feet (comprised of 100 links).
NTSQA0011
Question: How many links are in a Revenue Chain?
Answer: 16 links, with a total length of 33 feet.
NTSQA0012
Question: What are the two standard lengths for a Metric Chain?
Answer: 20m and 30m.
NTSQA0013
Question: What is the chemical composition of an Invar Tape?
Answer: An alloy of 36% Nickel and 64% Steel.
NTSQA0014
Question: Why is Invar Tape considered the best for baseline measurements?
Answer: Because it has an extremely low coefficient of thermal expansion, making it stable against temperature changes.
NTSQA0015
Question: When is Chain Surveying most suitable?
Answer: For small, fairly level ground areas with few details.
NTSQA0016
Question: What is a Base Line in a survey framework?
Answer: The longest and most important central line upon which the accuracy of the entire survey depends.
NTSQA0017
Question: What is the function of Check Lines?
Answer: They are used to verify the accuracy of the framework and the plotting.
NTSQA0018
Question: Why are Tie Lines established?
Answer: To locate subsidiary or interior details and to check the accuracy of the main survey lines.
NTSQA0019
Question: Define an "Offset" in surveying.
Answer: It is the lateral distance measured from the main survey line to locate an object.
NTSQA0020
Question: What are Cumulative Errors?
Answer: Errors that always occur in the same direction and increase as the survey progresses.
NTSQA0021
Question: What are Compensating Errors?
Answer: Errors that occur in both directions and tend to cancel each other out over a series of observations.
NTSQA0022
Question: What is the nature of Sag Correction in taping?
Answer: It is always Negative, as the sagged tape measures a distance longer than the actual straight line.
NTSQA0023
Question: Provide the formula for Slope Correction.
Answer: $C_s = h^2 / 2L$ (where $h$ is the vertical height and $L$ is the slope length).
Compass Surveying
NTSQA0024
Question: Where is the zero-degree mark located on a Prismatic Compass?
Answer: At the South end.
NTSQA0025
Question: Where are the zero-degree marks located on a Surveyor’s Compass?
Answer: At both the North and South ends.
NTSQA0026
Question: How are graduations marked on a Prismatic Compass?
Answer: They are marked inverted (upside down) and range from $0^\circ$ to $360^\circ$.
NTSQA0027
Question: What does WCB stand for?
Answer: Whole Circle Bearing.
NTSQA0028
Question: What does QB (or Reduced Bearing) stand for?
Answer: Quadrantal Bearing.
NTSQA0029
Question: What is Magnetic Declination?
Answer: The horizontal angle between the True North and the Magnetic North.
NTSQA0030
Question: What are Isogonic Lines?
Answer: Lines on a map joining points that have the same magnetic declination.
NTSQA0031
Question: What are Agonic Lines?
Answer: Lines joining points of zero magnetic declination.
NTSQA0032
Question: What is the value of the "Dip of the Needle" at the Equator?
Answer: Zero ($0^\circ$).
NTSQA0033
Question: What is the value of the "Dip of the Needle" at the magnetic poles?
Answer: $90^\circ$.
NTSQA0034
Question: What causes "Local Attraction"?
Answer: Magnetic interference from nearby objects like electric lines, steel structures, or iron deposits.
NTSQA0035
Question: How do you check if a line is free from Local Attraction?
Answer: If the difference between the Fore Bearing (FB) and Back Bearing (BB) is exactly $180^\circ$.
NTSQA0036
Question: Does True Bearing change with time?
Answer: No, True Bearing remains constant.
Levelling
NTSQA0037
Question: What is the primary use of a Dumpy Level?
Answer: To find the relative elevation difference between two or more points.
NTSQA0038
Question: Define Bench Mark (BM).
Answer: A fixed point of known elevation (Reduced Level) used as a reference.
NTSQA0039
Question: What is a Back Sight (BS)?
Answer: The first staff reading taken on a point of known elevation after the instrument is set up.
NTSQA0040
Question: What is a Fore Sight (FS)?
Answer: The last staff reading taken before shifting the instrument or finishing the work.
NTSQA0041
Question: What is the Line of Collimation?
Answer: The imaginary line passing through the intersection of the cross-hairs and the optical center of the objective lens.
NTSQA0042
Question: What are the three checks for the Rise and Fall method?
Answer: $\sum BS - \sum FS = \sum Rise - \sum Fall = Last RL - First RL$.
NTSQA0043
Question: Why is the Height of Instrument (HI) method faster?
Answer: Because it requires fewer arithmetic calculations for intermediate points.
NTSQA0044
Question: What is the sign of Curvature Correction?
Answer: Always Negative.
NTSQA0045
Question: What is the sign of Refraction Correction?
Answer: Always Positive.
NTSQA0046
Question: Provide the Combined Correction formula for levelling.
Answer: $C = 0.0673 D^2$ (expressed as a Negative value).
NTSQA0047
Question: When is Reciprocal Levelling used?
Answer: When an obstacle like a river or a wide valley prevents balancing of sights.
NTSQA0048
Question: What errors are eliminated by Reciprocal Levelling?
Answer: Errors due to Earth's curvature, atmospheric refraction, and collimation error.
NTSQA0049
Question: How is bubble tube sensitivity improved?
Answer: By having a larger radius of curvature for the tube.
Contouring
NTSQA0050
Question: Define a Contour Line.
Answer: A line on a map joining points that have the same elevation.
NTSQA0051
Question: What is a Contour Interval?
Answer: The constant vertical distance between two consecutive contour lines.
NTSQA0052
Question: What is Horizontal Equivalent?
Answer: The horizontal distance between any two consecutive contour lines.
NTSQA0053
Question: How are contours spaced on a steep slope?
Answer: They are closely spaced.
NTSQA0054
Question: How are contours spaced on a gentle slope?
Answer: They are widely spaced.
NTSQA0055
Question: Where do contour lines cross each other?
Answer: Only in the case of an Overhanging Cliff.
NTSQA0056
Question: What happens to contours in the case of a Vertical Cliff?
Answer: Multiple contour lines merge to form a single line.
NTSQA0057
Question: What do closed contours with higher values inside represent?
Answer: A hill or a ridge.
NTSQA0058
Question: What do closed contours with lower values inside represent?
Answer: A depression, hollow, or pond.
Theodolite & Traversing
NTSQA0059
Question: What is the purpose of a Theodolite?
Answer: Measuring both horizontal and vertical angles with high precision.
NTSQA0060
Question: What is a Transit Theodolite?
Answer: A theodolite whose telescope can be rotated $180^\circ$ in the vertical plane about its horizontal axis.
NTSQA0061
Question: What is the process of "Changing Face"?
Answer: Switching from "Face Left" to "Face Right" to eliminate instrument errors.
NTSQA0062
Question: Define "Swing of Telescope."
Answer: Rotating the telescope in the horizontal plane about its vertical axis.
NTSQA0063
Question: List the fundamental lines of a theodolite.
Answer: Vertical axis, Horizontal (Trunnion) axis, Line of Collimation, Bubble line.
NTSQA0064
Question: What are the temporary adjustments of a theodolite?
Answer: Centering, Levelling, and Elimination of Parallax (Focussing).
NTSQA0065
Question: Why are permanent adjustments performed?
Answer: To establish a fixed relationship between the fundamental lines of the instrument.
NTSQA0066
Question: What is the typical least count of a Transit Theodolite?
Answer: 20 seconds ($20"$).
NTSQA0067
Question: What is the least count of a Prismatic Compass?
Answer: 30 minutes ($30'$).
NTSQA0068
Question: What is a Traverse?
Answer: A series of connected survey lines whose lengths and bearings are measured.
NTSQA0069
Question: Provide the formula for Closing Error ($e$).
Answer: $e = \sqrt{(\sum L)^2 + (\sum D)^2}$ (where $L$ is Latitude and $D$ is Departure).
NTSQA0070
Question: When is Bowditch’s Rule applied?
Answer: When linear and angular measurements are assumed to be equally accurate.
NTSQA0071
Question: When is the Transit Rule applied?
Answer: When angular measurements are more accurate than linear measurements.
NTSQA0072
Question: What is the formula for Latitude ($L$)?
Answer: $L = l \cos \theta$.
NTSQA0073
Question: What is the formula for Departure ($D$)?
Answer: $D = l \sin \theta$.
Tacheometry & Plane Table
NTSQA0074
Question: Where is Tacheometry surveying primarily performed?
Answer: In rough, hilly, or broken terrain where chaining is difficult.
NTSQA0075
Question: What is a Tacheometer?
Answer: A transit theodolite fitted with a stadia diaphragm.
NTSQA0076
Question: What is the standard value of the Multiplying Constant ($k$)?
Answer: Usually 100 ($f/i$).
NTSQA0077
Question: What is the formula for the Additive Constant ($c$)?
Answer: $c = f + d$.
NTSQA0078
Question: What is the effect of an Anallatic Lens?
Answer: It makes the additive constant zero ($c=0$), simplifying distance calculations.
NTSQA0079
Question: What is the function of Stadia Hairs?
Answer: To take staff intercepts for calculating horizontal distances and vertical heights.
NTSQA0080
Question: What is the main advantage of Plane Table surveying?
Answer: Plotting and fieldwork are done simultaneously, reducing the chance of missing details.
NTSQA0081
Question: Define Orientation in plane tabling.
Answer: Keeping the table parallel to its position at previous stations.
NTSQA0082
Question: When is the Resection method used?
Answer: To locate the station point occupied by the plane table on the map.
NTSQA0083
Question: What is the Three-Point Problem?
Answer: A resection method to locate the table's position given three already plotted points.
NTSQA0084
Question: Where is Lehman’s Rule applied?
Answer: In the Trial and Error method of solving the Three-point problem.
NTSQA0085
Question: What is the greatest drawback of plane table surveying?
Answer: It is not suitable for work in wet or rainy weather.
Area, Volume, & Curves
NTSQA0086
Question: What instrument is used for measuring area on a map?
Answer: A Planimeter (specifically the Amsler Polar Planimeter).
NTSQA0087
Question: What is another name for Simpson’s Rule?
Answer: The Parabolic Rule.
NTSQA0088
Question: When can Simpson’s Rule be applied?
Answer: Only when the total number of offsets is Odd.
NTSQA0089
Question: Why is the Trapezoidal Rule less accurate than Simpson's?
Answer: Because it assumes the boundary between offsets is a straight line.
NTSQA0090
Question: What formula is used for calculating volume in earthwork?
Answer: The Prismoidal Formula.
NTSQA0091
Question: State the relationship between Degree ($D$) and Radius ($R$) of a curve.
Answer: $R = 1720 / D$ (for a 30m arc).
NTSQA0092
Question: What is the tangent length of a simple circular curve?
Answer: $T = R \tan(\Delta / 2)$.
NTSQA0093
Question: What is the formula for the length of a long chord?
Answer: $L = 2R \sin(\Delta / 2)$.
NTSQA0094
Question: Why is a Transition Curve provided?
Answer: To provide a gradual change in curvature from a straight path to a circular path.
NTSQA0095
Question: What is considered the ideal transition curve?
Answer: The Clothoid (Euler) spiral.
Modern Surveying & Others
NTSQA0096
Question: What parameters can a Total Station measure?
Answer: Horizontal/vertical angles, slope distances, and 3D coordinates.
NTSQA0097
Question: What does GPS stand for?
Answer: Global Positioning System.
NTSQA0098
Question: How many satellites are minimum required for a 3D GPS fix?
Answer: 4 satellites.
NTSQA0099
Question: Define Photogrammetry.
Answer: The science of obtaining reliable measurements and maps from photographs.
NTSQA0100
Question: What is "Sounding" in surveying?
Answer: The process of measuring depths below a water surface (Hydrographic survey).
Theodolite & Angle Measurement
NTSQA0101
Question: What is the "Horizontal Axis" of a theodolite also known as?
Answer: It is also known as the Trunnion Axis, about which the telescope rotates in the vertical plane.
NTSQA0102
Question: What is a "Vertical Circle" in a theodolite used for?
Answer: It is used to measure vertical angles (angles of elevation or depression) relative to the horizontal line of sight.
NTSQA0103
Question: Define "Centering" in theodolite adjustments.
Answer: The process of setting the vertical axis of the theodolite exactly over the center of the station mark using a plumb bob or optical plummet.
NTSQA0104
Question: What is "Transiting"?
Answer: The operation of rotating the telescope $180^{\circ}$ in the vertical plane about its horizontal axis.
NTSQA0105
Question: What error is eliminated by taking the average of both Face Left and Face Right readings?
Answer: It eliminates the error due to the line of collimation not being perpendicular to the horizontal axis and the error due to the horizontal axis not being perpendicular to the vertical axis.
NTSQA0106
Question: What is the "Telescope Normal" condition?
Answer: It is the condition when the vertical circle is to the left of the observer (Face Left).
NTSQA0107
Question: What is the "Index Error" in a theodolite?
Answer: The error caused when the vertical circle does not read exactly $0^{\circ}$ (or $90^{\circ}/270^{\circ}$ depending on the type) when the line of sight is perfectly horizontal.
NTSQA0108
Question: Define the "Plate Level" test.
Answer: A test performed to ensure that the vertical axis of the theodolite is truly vertical when the plate bubbles are centered.
Traversing & Coordinate Geometry
NTSQA0109
Question: What is an "Open Traverse"?
Answer: A traverse that starts from a known point and ends at an unknown point, making it impossible to check for closing errors mathematically.
NTSQA0110
Question: What is a "Closed Traverse"?
Answer: A traverse that either returns to its starting point or connects two points whose positions are already known.
NTSQA0111
Question: What is "Balancing a Traverse"?
Answer: The process of adjusting the observed latitudes and departures of traverse legs so that their algebraic sums equal zero (for a closed loop).
NTSQA0112
Question: In which quadrant is both Latitude and Departure positive?
Answer: The First Quadrant (North-East).
NTSQA0113
Question: If the Latitude is negative and Departure is positive, in which quadrant does the line lie?
Answer: The Second Quadrant (South-East).
NTSQA0114
Question: Define "Consecutive Coordinates."
Answer: The Latitude and Departure of a point measured with respect to the immediately preceding point.
NTSQA0115
Question: Define "Independent Coordinates" (Total Coordinates).
Answer: The coordinates of a point measured with respect to a common fixed origin (the starting point of the survey).
NTSQA0116
Question: What is the "Gale’s Traverse Table" used for?
Answer: It is a standardized table used for recording observations and calculating the adjusted coordinates of a traverse.
NTSQA0117
Question: What is "Angular Misclosure"?
Answer: The difference between the sum of measured interior angles and the theoretical sum $(2n - 4) \times 90^{\circ}$.
NTSQA0118
Question: What is the "Relative Precision" of a traverse?
Answer: It is the ratio of the closing error to the total perimeter of the traverse (e.g., 1:5000).
Tacheometry & Distant Measurements
NTSQA0119
Question: What is the "Stadia Interval" ($i$)?
Answer: The fixed distance between the upper and lower stadia hairs on the diaphragm of a tacheometer.
NTSQA0120
Question: What is the "Staff Intercept" ($s$)?
Answer: The difference between the readings of the upper and lower stadia hairs as seen on the levelling staff.
NTSQA0121
Question: When the line of sight is horizontal, what is the formula for horizontal distance ($D$) in tacheometry?
Answer: $D = ks + c$.
NTSQA0122
Question: What is the primary purpose of an "Anallatic Lens"?
Answer: To move the analytical center of the objective lens to the vertical axis of the instrument, thereby making the additive constant ($c$) equal to zero.
NTSQA0123
Question: Why is a Tacheometer preferred over a Chain in broken ground?
Answer: Because it measures distances optically, eliminating the physical difficulty and errors associated with dragging a chain over obstacles and uneven slopes.
NTSQA0124
Question: What is the "Subtense Bar" method?
Answer: A method of tacheometry where a horizontal bar of fixed length is used at the target point, and the horizontal angle subtended by it at the instrument is measured.
Curve Surveying
NTSQA0125
Question: What is a "Simple Circular Curve"?
Answer: A curve consisting of a single arc of a circle connecting two tangents.
NTSQA0126
Question: Define the "Point of Curve" (PC).
Answer: The point where the alignment changes from a straight line to a circular curve.
NTSQA0127
Question: Define the "Point of Tangency" (PT).
Answer: The point where the circular curve ends and the alignment becomes straight again.
NTSQA0128
Question: What is the "Deflection Angle" ($\Delta$) of a curve?
Answer: The angle between the back tangent and the forward tangent.
NTSQA0129
Question: What is "Super-elevation" (Cant)?
Answer: The raising of the outer edge of a road or railway track above the inner edge to counteract centrifugal force on a curve.
NTSQA0130
Question: Define the "Mid-ordinate" of a curve.
Answer: The distance from the midpoint of the long chord to the midpoint of the curve.
NTSQA0131
Question: What is a "Vertical Curve"?
Answer: A curve (usually parabolic) provided to connect two different gradients for a smooth transition.
NTSQA0132
Question: What is a "Summit Curve"?
Answer: A vertical curve with convexity upwards, formed when an ascending gradient meets a descending gradient.
NTSQA0133
Question: What is a "Valley Curve" (Sag Curve)?
Answer: A vertical curve with convexity downwards, formed when a descending gradient meets an ascending gradient.
NTSQA0134
Question: What is Rankine’s Method used for?
Answer: It is a method of setting out circular curves using a theodolite and tangential angles.
Plane Table Surveying (In-depth)
NTSQA0135
Question: What is an "Alidade"?
Answer: A straight-edge ruler with sighting vanes used in plane table surveying to draw lines of sight.
NTSQA0136
Question: What is the difference between a Plain Alidade and a Telescopic Alidade?
Answer: A Plain Alidade uses simple slits for sighting, while a Telescopic Alidade includes a telescope for better accuracy and sighting distant or elevated objects.
NTSQA0137
Question: What is the purpose of a "U-Frame" (Plumbing Fork) in Plane Table surveying?
Answer: It is used to center the point on the drawing sheet exactly over the station on the ground.
NTSQA0138
Question: What is "Orientation" by Trough Compass?
Answer: Aligning the plane table such that the magnetic north line drawn at the first station matches the magnetic north at subsequent stations.
NTSQA0139
Question: What is "Orientation" by Back Sighting?
Answer: Aligning the table by sighting back to a previously occupied station whose position has already been plotted.
NTSQA0140
Question: Why is the "Three-Point Problem" more efficient than the "Two-Point Problem"?
Answer: It requires fewer station setups and is mathematically more robust, though the two-point problem is used when only two known points are visible.
Levelling & Hypsometry (Advanced)
NTSQA0141
Question: What is "Fly Levelling"?
Answer: A type of levelling done to determine the approximate RL of a distant point from a known benchmark, usually using only back sights and fore sights.
NTSQA0142
Question: What is "Profile Levelling"?
Answer: Levelling performed along a central line to determine the elevations of points at regular intervals, used for designing roads or canals.
NTSQA0143
Question: What is "Check Levelling"?
Answer: Levelling done at the end of a day's work to verify the accuracy by returning to the starting benchmark.
NTSQA0144
Question: Define "Cross-sectioning" in levelling.
Answer: Determining the elevations of points on lines perpendicular to the main alignment (profile).
NTSQA0145
Question: What is a "Change Point" (CP) or Turning Point?
Answer: A stable point on which both a fore sight and a back sight are taken when the instrument is being moved to a new position.
NTSQA0146
Question: What is "Hypsometry"?
Answer: The measurement of height or elevation above sea level, often using the boiling point of water.
NTSQA0147
Question: How does the boiling point of water change with altitude?
Answer: The boiling point decreases as the altitude increases because the atmospheric pressure is lower.
NTSQA0148
Question: What is "Barometric Levelling"?
Answer: Determining the elevation difference between points based on the difference in atmospheric pressure.
Contours & Earthwork
NTSQA0149
Question: What is the "Contour Gradient"?
Answer: A line on the ground surface that maintains a constant inclination to the horizontal.
NTSQA0150
Question: What is a "Saddle" in a contour map?
Answer: A low point between two higher areas (summits) or a gap in a ridge.
NTSQA0151
Question: How is the "Contour Interval" decided for a map?
Answer: It depends on the scale of the map, the purpose of the survey, the nature of the terrain, and available time/funds.
NTSQA0152
Question: What is "Direct Method" of contouring?
Answer: Locating points of a specific elevation directly on the ground using a level and then plotting them.
NTSQA0153
Question: What is "Indirect Method" of contouring?
Answer: Taking elevations at various random or grid points and then interpolating the contour lines between them.
NTSQA0154
Question: What is "Interpolation" of contours?
Answer: The process of estimating the position of contour lines between points of known elevation.
NTSQA0155
Question: Which method of interpolation is most accurate?
Answer: Arithmetic Calculation.
Area & Volume Calculations
NTSQA0156
Question: What is the "Prismoidal Excess"?
Answer: The difference between the volume calculated by the Trapezoidal (End-Area) rule and the Prismoidal rule.
NTSQA0157
Question: Why is Simpson's Rule generally preferred for area calculation?
Answer: Because it assumes the boundary is a series of parabolic arcs, providing a more accurate result for irregular boundaries.
NTSQA0158
Question: What is "Cross-sectional Area" in earthwork?
Answer: The area of a vertical plane perpendicular to the centerline of a road or excavation.
NTSQA0159
Question: Define "Lead" and "Lift" in earthwork.
Answer: "Lead" is the horizontal distance over which excavated soil is transported, and "Lift" is the vertical distance.
Modern Surveying Equipment
NTSQA0160
Question: What are the components of a Total Station?
Answer: An electronic theodolite, an Electronic Distance Meter (EDM), and a microprocessor with internal storage.
NTSQA0161
Question: What is "EDM"?
Answer: Electronic Distance Measurement, which uses electromagnetic waves (like infrared or laser) to determine distance.
NTSQA0162
Question: How does a Total Station measure distance?
Answer: By measuring the "phase shift" or "travel time" of a reflected light pulse from a prism.
NTSQA0163
Question: What is a "Passive Remote Sensing"?
Answer: Sensing that detects natural radiation reflected or emitted by the Earth's surface (e.g., sunlight).
NTSQA0164
Question: What is "Active Remote Sensing"?
Answer: Sensing where the instrument emits its own energy (like Radar or Lidar) to scan objects.
NTSQA0165
Question: What is "GIS"?
Answer: Geographic Information System—a framework for gathering, managing, and analyzing spatial and geographic data.
NTSQA0166
Question: What is the "User Segment" in GPS?
Answer: It consists of the GPS receivers (like phones or surveying units) that receive signals from satellites.
NTSQA0167
Question: What is the "Space Segment" in GPS?
Answer: It consists of the constellation of satellites orbiting the Earth.
NTSQA0168
Question: What is "Differential GPS" (DGPS)?
Answer: An enhancement to standard GPS that uses a network of fixed ground-based reference stations to correct GPS signals for higher accuracy.
Photogrammetry & Hydrography
NTSQA0169
Question: What is "Tilted Photograph"?
Answer: An aerial photograph taken with the camera axis unintentionally tilted from the vertical.
NTSQA0170
Question: What is "Oblique Photograph"?
Answer: An aerial photograph taken with the camera axis intentionally inclined at a significant angle to the vertical.
NTSQA0171
Question: Define "Principal Point" in a photograph.
Answer: The point where the optical axis of the camera intersects the plane of the photograph.
NTSQA0172
Question: What is "Overlap" in aerial photography?
Answer: The area common to two successive photographs (usually 60% longitudinal overlap).
NTSQA0173
Question: What is "Side Lap"?
Answer: The area common to two adjacent strips of photographs (usually 30%).
NTSQA0174
Question: What is "Fiducial Marks"?
Answer: Small markers at the edges or corners of an aerial photograph used to define the principal point.
NTSQA0175
Question: What is a "Hydrographic Survey"?
Answer: A survey dealing with bodies of water, including mapping the underwater topography (bathymetry).
NTSQA0176
Question: What is an "Echo Sounder"?
Answer: An instrument used to determine water depth by measuring the time it takes for sound waves to reflect off the bottom.
NTSQA0177
Question: What is "Tide Gauge"?
Answer: An instrument used to measure and record the changes in water level (tides).
General Engineering Surveying
NTSQA0178
Question: What is a "Setting Out" operation?
Answer: The process of transferring the measurements from a plan or drawing onto the actual ground surface for construction.
NTSQA0179
Question: What is a "Batter Rail"?
Answer: A horizontal board used in setting out to indicate the slope of an excavation or embankment.
NTSQA0180
Question: What is "Sight Rail"?
Answer: Horizontal boards set at a fixed height above the required level to control the gradient of a trench or pipe.
NTSQA0181
Question: What is a "Bonning Rod"?
Answer: A T-shaped rod used in conjunction with sight rails to maintain a uniform gradient.
NTSQA0182
Question: Define "Precision" in surveying.
Answer: The degree of consistency or repeatability of a measurement.
NTSQA0183
Question: Define "Accuracy" in surveying.
Answer: How close a measurement is to its true or absolute value.
NTSQA0184
Question: What is a "Blunder"?
Answer: A gross mistake caused by carelessness or poor judgment (e.g., misreading a tape).
NTSQA0185
Question: What is a "Random Error"?
Answer: Small, unpredictable errors that remain after systematic errors have been removed.
NTSQA0186
Question: What is the "Law of Accidental Errors"?
Answer: It states that small errors are more frequent than large ones and that positive and negative errors are equally likely.
Miscellaneous Core Concepts
NTSQA0187
Question: What is the "Shrinkage Factor" ($SF$)?
Answer: $SF = \text{Shrunk Length} / \text{Original Length}$.
NTSQA0188
Question: If the RF is 1:500 and the shrinkage factor is 0.9, what is the Shrunk Scale?
Answer: $1 / (500 / 0.9) = 1 / 555.55$.
NTSQA0189
Question: What is a "Plan"?
Answer: A large-scale graphical representation of a small area (e.g., a house plan).
NTSQA0190
Question: What is a "Map"?
Answer: A small-scale graphical representation of a large area (e.g., a country map).
NTSQA0191
Question: What is "Oblique Offset"?
Answer: Any offset that is not perpendicular to the main survey line.
NTSQA0192
Question: What is the use of "Optical Square"?
Answer: It is used to set out a line at right angles ($90^{\circ}$) to the chain line.
NTSQA0193
Question: On what principle does an Optical Square work?
Answer: Double reflection.
NTSQA0194
Question: What is "Ranging"?
Answer: The process of establishing intermediate points on a straight line between two fixed end stations.
NTSQA0195
Question: What is "Indirect Ranging" (Reciprocal Ranging)?
Answer: Used when the end stations are not intervisible due to high ground or an obstacle.
NTSQA0196
Question: What is the length of a link in a 20m Metric Chain?
Answer: 20 cm ($20\text{ m} / 100\text{ links}$).
NTSQA0197
Question: What are "Tallies" in a chain?
Answer: Brass tags attached to the chain at every 5m or 10m interval to facilitate quick reading.
NTSQA0198
Question: What is the "Horizontal Equivalent" of a slope?
Answer: $L \cos \theta$, where $L$ is the slope distance.
NTSQA0199
Question: What is "Magnetic Dip"?
Answer: The vertical angle made by a freely suspended magnetic needle with the horizontal plane.
NTSQA0200
Question: What are "Agonic Lines"?
Answer: Lines passing through points of zero magnetic declination.
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