Question 1

Rectangle bearings and parallel sides: ABCD is a rectangular plot. If the whole-circle bearing (WCB) of side AB is 75°, what is the bearing of the opposite side DC (taken from D to C)?

Accepted Answer

Introduction / Context: In plane surveying, parallel lines have identical bearings when measured in the same direction. A rectangle has opposite sides parallel, so the bearing of DC should match AB provided we observe DC from D to C (i.e., the same direction of travel along that pair of parallels). This conceptual check is common in traverse adjustment and plotting. Given Data / Assumptions: ABCD is a rectangle, so AB ∥ DC and BC ∥ AD. Bearing of AB (A→B) is 75° (WCB). We need bearing of DC from D→C. Concept / Approach: Parallel lines share the same direction. The side DC when taken from D→C runs parallel and in the same sense as AB from A→B. Therefore, their bearings are equal. Note the difference between a “forward bearing” of a line and its “back bearing” (which differs by 180°). Here we are not asked for the back bearing of AB; we are asked for the forward bearing of DC, which equals the forward bearing of AB. Step-by-Step Solution: Identify parallel sides: AB ∥ DC.Match direction: A→B corresponds to D→C for these parallels.Equal bearings for equal directions on parallels → Bearing(DC) = Bearing(AB) = 75°.Therefore, select 75°. Verification / Alternative check: Back bearing of AB would be 75° + 180° = 255°. That would correspond to C→D, not D→C. This cross-check confirms that D→C must be 75° to stay parallel to A→B in the same sense. Why Other Options Are Wrong: 255°: this is the back bearing of AB (B→A) or the bearing of CD (C→D), not of DC. 105° and 285°: do not match either the parallel or perpendicular directions in this case. Common Pitfalls: Confusing which way along a side the bearing is taken; mixing forward and back bearings; forgetting that opposite sides of a rectangle are parallel and have identical forward bearings when taken in consistent directions. Final Answer: 75°

Question 2

Highway alignment – lemniscate transition curves: A lemniscate is considered not to remain transitional throughout if the deflection angle of the curve is greater than which value?

Accepted Answer

Introduction / Context: Transition curves provide a gradual change of curvature from a tangent (infinite radius) to a circular arc (finite radius), improving comfort and safety. Lemniscate curves are a family of spirals used where large deflection angles are involved. The question checks the commonly cited limit beyond which a lemniscate does not remain transitional throughout its length. Given Data / Assumptions: Transition curve purpose: vary curvature progressively to avoid sudden lateral acceleration. Lemniscate properties are used for large deflection angles but are bounded by practical geometry. “Transitional throughout” means the entire curve maintains the desired monotonic curvature change. Concept / Approach: Standard references note that lemniscates behave as desirable transition spirals up to about a right angle of total deflection. Beyond this, the curvature progression or practical setting out may cease to meet the continuous transition requirement for the entire extent, and composite solutions are adopted. Thus, the threshold value used in classical design problems is 90°. Step-by-Step Solution: Recognize the role of a transition spiral: curvature increases from zero to a target value smoothly.Recall lemniscate usage: good for substantial deflection but with a conventional upper bound.Apply the cited criterion: not transitional throughout if the deflection angle exceeds 90°.Select the nearest exact option: 90°. Verification / Alternative check: Design literature often contrasts lemniscates with clothoids; while clothoids can be extended, lemniscates are quoted with practical deflection limits to preserve the transitional property throughout. Why Other Options Are Wrong: 45° and 60°: overly conservative; lemniscates remain transitional within these smaller angles. 120° and 180°: too high; beyond 90° the entire curve may not satisfy a single transition spiral behavior. Common Pitfalls: Assuming all transition curves are interchangeable without limits; ignoring vehicle dynamics and sight distance which also govern feasible deflection management. Final Answer: 90°

Question 3

Precision levelling: In a properly adjusted level, when the bubble is centered, the axis of the bubble tube becomes parallel to which line?

Accepted Answer

Introduction / Context: Accurate levelling depends on precise geometric relationships within the instrument. When a level is correctly adjusted and the bubble is centered, the line of collimation must be truly horizontal to ensure that staff readings represent vertical offsets from a horizontal plane of collimation. Given Data / Assumptions: The instrument has undergone proper permanent and temporary adjustments. Bubble tube axis is perpendicular to the vertical axis after adjustment. The line of collimation has been set parallel to the bubble tube axis. Concept / Approach: In a correctly adjusted level: when the bubble is centered, the bubble tube axis is horizontal. Since the line of collimation is made parallel to the bubble tube axis during adjustment, it is also horizontal. The phrase “axis of the telescope” is ambiguous (mechanical tube axis), whereas “line of collimation” is the exact optical line used for sighting staff graduations. Step-by-Step Solution: Center the bubble to create a horizontal reference.Use the adjustment that sets the line of collimation parallel to the bubble tube axis.Infer parallelism: bubble axis ∥ line of collimation when centered.Therefore, the correct relation is with the line of collimation. Verification / Alternative check: Two-peg test and collimation checks confirm that, with the bubble centered, foresight and backsight differences reflect true level differences, implying horizontal collimation line. Why Other Options Are Wrong: “Line of sight” is sometimes used loosely, but the rigorous term in survey optics is “line of collimation.” “Axis of the telescope” refers to the mechanical tube axis, not necessarily coincident with the optical collimation line. “None of these” is invalid because the exact parallelism is known. Common Pitfalls: Confusing mechanical alignment with optical collimation; assuming a centered bubble guarantees accuracy without prior instrument adjustment. Final Answer: Line of collimation (line through cross-hair intersection and objective center)

Question 4

Computation by Simpson’s 1/3 rule (double ordinates method): If d is the uniform interval between consecutive ordinates h1, h2, …, hn along a baseline, the approximate area under the boundary by Simpson’s rule is

Accepted Answer

Introduction / Context: Area computation from offset ordinates is a staple of surveying. Simpson’s 1/3 rule improves accuracy by fitting parabolas through successive pairs of intervals. Knowing the correct weight pattern on even and odd interior ordinates avoids large numerical errors in earthwork or plotting calculations. Given Data / Assumptions: Ordinates h1 to hn are measured at equal spacing d along a straight baseline. Number of intervals (n − 1) is even, as required by Simpson’s 1/3 rule. Boundary is sufficiently smooth for parabolic approximation to be reasonable. Concept / Approach: Simpson’s 1/3 rule assigns weights 1 to the first and last ordinates, weight 4 to even-numbered interior ordinates, and weight 2 to odd-numbered interior ordinates. The composite area is then multiplied by d/3. This contrasts with the trapezoidal rule, which uses weights 1, 2, …, 2, 1 and a factor d/2, and with crude averaging methods not suited to curved boundaries. Step-by-Step Solution: Ensure an even number of intervals: n − 1 must be even.Apply weight pattern: 1 for ends, 4 for h2, h4, …, h_{n−1}, and 2 for h3, h5, …, h_{n−2}.Form the sum S = h1 + hn + 4Σ(even interiors) + 2Σ(odd interiors).Compute area: Area = (d / 3) * S. Verification / Alternative check: For a quadratic boundary y = ax^2 + bx + c, Simpson’s rule gives the exact area, which confirms the weight pattern and the d/3 multiplier. Why Other Options Are Wrong: (d / 2) formula is the trapezoidal rule, not Simpson’s. Average-of-ordinates times d is a rough method, typically inaccurate for curved lines. Option D swaps the 4 and 2 weights, which is incorrect for Simpson’s 1/3 rule. Common Pitfalls: Using Simpson’s rule with an odd number of intervals; mixing up which interior ordinates are “even” and “odd” relative to h1; forgetting the d/3 factor. Final Answer: Area = (d / 3) * [ h1 + hn + 4(h2 + h4 + … + h_{n-1}) + 2(h3 + h5 + … + h_{n-2}) ]

Question 5

Magnetic meridian definition: At any station, the magnetic meridian is the direction given by which condition on the magnetic needle?

Accepted Answer

Introduction / Context: Compass bearings are referenced to the magnetic meridian, which is defined physically by the equilibrium direction of a magnetic needle at the location. However, practical instruments must eliminate biases from imbalance and local attraction to represent the true magnetic field direction. Given Data / Assumptions: The needle is supported with minimal friction and correct balance for local dip. Nearby ferrous objects or electric currents can distort readings (local attraction). The desired reference is the undisturbed magnetic field direction at the station. Concept / Approach: The magnetic meridian is the direction assumed by a freely suspended, properly balanced magnetic needle uninfluenced by local attraction. Balancing compensates for dip so the needle remains essentially horizontal, while avoiding local attraction ensures the indicated direction aligns with Earth’s magnetic field and not with nearby stray fields or iron masses. Step-by-Step Solution: Ensure correct balance using rider weights appropriate to latitude (compensating dip).Eliminate local attraction sources by clearing the vicinity or checking from different stations.Allow the freely suspended needle to settle; the direction it assumes is the magnetic meridian.Thus, the full condition is: properly balanced and free from local attraction. Verification / Alternative check: Compass “local attraction test” compares forward and back bearings; discrepancies indicate disturbance. Removing such effects restores alignment with the magnetic meridian. Why Other Options Are Wrong: Merely “freely suspended” is insufficient if the needle is unbalanced. Balance alone is not enough if local attraction remains. An iron pivot can create attraction and bias. Common Pitfalls: Ignoring vehicle bodies, tools, or power lines near the compass; failing to re-balance after moving long distances in latitude. Final Answer: A properly balanced magnetic needle that is free and uninfluenced by local attraction

Question 6

Railway engineering – equilibrium super elevation (cant): For a locomotive running at speed V (km/h) on a circular curve of radius R (m), with g as acceleration due to gravity (m/s^2) and G as the distance between running faces of rails (m), what is…

Accepted Answer

Introduction / Context: On curved tracks, raising the outer rail (super elevation or cant) balances the lateral acceleration so that the resultant pressure acts normal to the rail plane. The equilibrium cant depends on speed, curve radius, and track gauge. This relation is essential for safe and comfortable railway operation and for setting out permanent way on curves. Given Data / Assumptions: V is train speed in km/h. R is curve radius in meters. G is the distance between running faces of the rails (m). g ≈ 9.81 m/s^2 is acceleration due to gravity. Concept / Approach: For equilibrium: e / G = v^2 / (g * R), where v is speed in m/s. Converting V (km/h) to v: v = V / 3.6. Substituting gives e = G * (V^2 / 3.6^2) / (g * R) = (G * V^2) / (g * R * 12.96). With g ≈ 9.81, the denominator becomes about 127; hence, the practical design formula is e = (G * V^2) / (127 * R), with e in meters when G is in meters and V in km/h. Step-by-Step Solution: Start with equilibrium: e / G = v^2 / (g * R).Convert speed: v = V / 3.6, so v^2 = V^2 / 12.96.Compute: e = G * (V^2 / 12.96) / (g * R) = (G * V^2) / (12.96 * g * R).Approximate 12.96 * g ≈ 127 → e = (G * V^2) / (127 * R). Verification / Alternative check: For standard gauge G = 1.676 m and V = 60 km/h, R = 300 m, e = 1.676 * 3600 / (127 * 300) ≈ 0.158 m (≈ 158 mm), matching handbook values. Why Other Options Are Wrong: e = (V^2) / (g * R): missing G factor and wrong units. e = (G * g) / (R * V): incorrect dependence; cant increases with V^2, not decreases with V. e = (R * G) / (127 * V^2): inverted speed dependence. Common Pitfalls: Mixing unit systems (m/s vs km/h); forgetting that e is measured vertically at the rail; applying equilibrium cant to circumstances that require limiting cant due to low-speed freight operations. Final Answer: e = (G * V^2) / (127 * R)

Question 7

Optics used in surveying telescopes: Which statement set correctly describes the power of a lens and its sign convention and unit?

Accepted Answer

Introduction / Context: Surveying instruments such as levels and theodolites use compound lenses. Understanding “power” helps relate focal length to optical strength and ensures correct interpretation when lenses are combined or replaced during maintenance. This question checks the standard definition, sign convention, and unit of lens power used in optics. Given Data / Assumptions: Thin lens approximation is valid for first-order calculations. Focal length f is expressed in meters for power calculations. Sign convention follows the usual physics/optics practice. Concept / Approach: Lens power P is defined as P = 1 / f, with f in meters. Converging lenses (convex) have positive focal lengths and thus positive power; diverging lenses (concave) have negative focal lengths and thus negative power. The SI unit is the diopter (1 diopter = 1 m^-1). These conventions are used when combining thin lenses: P_total ≈ P1 + P2 for lenses in contact. Step-by-Step Solution: Write the definition: P = 1 / f (f in meters).Apply sign: convex → positive f → positive P; concave → negative f → negative P.Note the unit: diopter (m^-1).Combine statements: all are simultaneously true. Verification / Alternative check: Example: a 0.25 m focal length lens has P = 4 D; a −0.5 m focal length lens has P = −2 D. Combining them in contact gives net ≈ 2 D, validating the definitions and signs. Why Other Options Are Wrong: Any individual statement alone is incomplete; the complete and correct description is captured only by “All of the above.” Common Pitfalls: Using centimeters for f while quoting power in diopters; confusing magnification with power; ignoring that real instruments use multi-element designs but the power definition still applies element-wise. Final Answer: All of the above

Question 8

Deflection surveying — to directly observe a right deflection angle at a station, how should the theodolite be set on the back station reading before turning to the forward line? Choose the most appropriate setting.

Accepted Answer

Introduction / Context: In route surveying and curve setting, deflection angles are frequently used to turn the forward direction from a back tangent. The reading you set on the back station determines whether the deflection to the new line is read directly and with the correct sense (right/left). This question reinforces the standard field convention for measuring a right deflection cleanly and unambiguously. Given Data / Assumptions: The instrument is centered and leveled at the point of deflection (station). The back station (back tangent) is sighted first to establish reference. A right deflection to the forward line must be read directly from the circle. Concept / Approach: When the vernier/circle is set to 180° while sighting the back station, a clockwise turn to the forward line yields the right deflection angle as a direct reading. This convention minimizes sign confusions and aligns with many field books that list right deflections as positive clockwise rotations from the back tangent. Step-by-Step Solution: Center and level the theodolite at the station of deflection.Back-sight the previous station (back tangent) and clamp the lower plate.Set the horizontal circle to read 180° on the back station.Turn clockwise to the forward line; the circle now directly shows the right deflection angle. Verification / Alternative check: Field practice notes show that setting 0° on the back station typically makes left deflections read directly; setting 180° makes right deflections read directly. Crews maintain this habit to avoid transcription errors. Why Other Options Are Wrong: Zero on back station: Suits left deflections; not the standard for direct right deflection readings. 90°/270° on back station: Arbitrary and do not map the forward direction to the deflection directly. Common Pitfalls: Failing to re-zero or set 180° consistently between stations, causing sign flips in the field book. Final Answer: 180° on the back station

Question 9

Bearings — a line has reduced (quadrantal) bearing N 87° W. What is its whole circle bearing (WCB), measured clockwise from north (0°–360°)?

Accepted Answer

Introduction / Context: Survey lines may be expressed either as reduced (quadrantal) bearings like N θ E/W or S θ E/W, or as whole circle bearings (WCB) measured 0°–360° clockwise from true or magnetic north. Converting correctly between these systems is essential for plotting, computations, and using different instruments consistently. Given Data / Assumptions: Reduced bearing: N 87° W (i.e., 87° west of north). WCB is measured clockwise from north. Standard quadrant conventions apply. Concept / Approach: N 87° W lies in the northwest quadrant. From north (0°), rotating clockwise to the west side means passing through 360° back to just beyond it. The equivalent WCB is 360° − 87° = 273°. General rule: N θ W → WCB = 360° − θ; N θ E → θ; S θ E → 180° − θ; S θ W → 180° + θ. Step-by-Step Solution: Identify quadrant: N 87° W → NW.Compute WCB: 360° − 87° = 273°.State final bearing: 273°. Verification / Alternative check: Sketch axes and mark 0° at north; move clockwise nearly to west (270°) and add 3° more: 273°, which matches the conversion. Why Other Options Are Wrong: 87°: This would be N 87° E. 93°: Lies in NE quadrant; wrong side. 3°: Near north; not in NW quadrant. Common Pitfalls: Forgetting that N θ W and S θ E swap around 360° and 180° respectively; always visualize the quadrant. Final Answer: 273°

Question 10

Transit theodolite — when the instrument is not in perfect adjustment, which observing procedure still yields accurate deflection angles?

Accepted Answer

Introduction / Context: Theodolites may suffer from residual collimation or axis errors if not fully adjusted. However, careful observing procedures can remove or greatly reduce their effects so that deflection angles remain reliable. This is especially important during route surveys and curve setting where many short turns are made. Given Data / Assumptions: The instrument is not perfectly adjusted (small collimation/axis errors). Deflection angles must be measured as accurately as possible. Standard reversing (face left/face right) procedures are available. Concept / Approach: Observations in both positions of the telescope (normal and inverted) reverse the sign of collimation error. By taking readings in both faces and averaging, the error cancels, leaving the true angle. This is the essence of the double-sighting (repetition with faces reversed) procedure widely recommended for precise work with imperfectly adjusted instruments. Step-by-Step Solution: Back-sight with telescope normal (face left/right as per instrument), set the reference, and note the reading.Reverse the telescope (plunge), re-sight the same back station, and note the reading again.Turn to the forward station for both faces and compute the deflection angles.Average the two face results to obtain the corrected deflection angle. Verification / Alternative check: The face-averaging method is standard in geodetic practice; residuals indicate adjustment quality and random error magnitude. Why Other Options Are Wrong: Setting zero and plunging without dual observations does not inherently cancel collimation error. Turning directly in one face carries the full error into the reading. “None” is incorrect because the two-face method is known to work. Common Pitfalls: Failing to record both faces consistently; not re-sighting carefully on the same points can defeat the cancellation. Final Answer: Take two back sights: one with the telescope normal and one with the telescope inverted, then use the mean

Question 11

Bearings — if a line has whole circle bearing (WCB) 120°, what is its reduced (quadrantal) bearing?

Accepted Answer

Introduction / Context: Reduced bearings express directions within one of four quadrants relative to north or south. Converting accurately from whole circle bearings (0°–360° clockwise from north) to reduced bearings is a routine but crucial task in plotting and computations. Given Data / Assumptions: WCB = 120°. WCB is measured from north, clockwise. Reduced bearing should be stated as N/S θ E/W. Concept / Approach: Angles 90°–180° lie in the southeast (SE) quadrant. The reduced bearing equals S (180° − WCB) E. Here, 180° − 120° = 60°, so the reduced bearing is S 60° E. Step-by-Step Solution: Identify the quadrant: 120° is between 90° and 180° → SE.Compute interior angle with south: 180° − 120° = 60°.State reduced bearing: S 60° E. Verification / Alternative check: Sketching the axes confirms the direction: 30° beyond east towards south does not fit; it is indeed 60° east of south. Why Other Options Are Wrong: S 20° E: Wrong magnitude. N 120° E / N 60° E: These lie in NE quadrant, not SE. Common Pitfalls: Confusing which reference (north or south) to use per quadrant; 90°–180° always references south. Final Answer: S 60° E

Question 12

Transition curves — why are transition (spiral) curves provided at the ends of a circular curve in highway/rail alignment? Choose the most correct objective.

Accepted Answer

Introduction / Context: Vehicles cannot safely jump from a straight tangent (zero curvature) to a full circular curve at once. Transition curves (such as clothoids/spirals) smooth this change by gradually introducing curvature and the associated super-elevation, enhancing comfort and safety and reducing lateral jerk. Given Data / Assumptions: Plan (horizontal) curve design is considered. Super-elevation is applied progressively along the transition. Vertical gradient changes are handled by separate vertical curves. Concept / Approach: A proper transition curve ensures curvature varies linearly with length so that lateral acceleration and its rate of change (jerk) are controlled. At the same time, the roadway crossfall is rotated gradually to the required super-elevation. Vertical gradient transitions are unrelated and are designed with parabolic vertical curves, not with horizontal transitions. Step-by-Step Solution: From the tangent, start with zero curvature and ramp up to the design circular curvature smoothly.Simultaneously, rotate the cross-section to increase super-elevation to the target value.Avoid including vertical grade changes here; those belong to vertical curve design.Thus, objectives (a) and (b) are correct together. Verification / Alternative check: Design manuals specify transition length based on speed, design radius, comfort jerk limits, and super-elevation runoff, confirming the dual role. Why Other Options Are Wrong: (a) alone omits the essential super-elevation runoff. (b) alone omits the curvature ramp. (c) confuses horizontal transitions with vertical curves. (d) is incorrect because (a)+(b) is the correct purpose. Common Pitfalls: Mixing vertical and horizontal design elements; forgetting that comfort depends on controlling jerk as curvature changes. Final Answer: Both (a) and (b)

Question 13

Vertical curves — for an up-grade of +g1% meeting a down-grade of g2% (summit curve) with total curve length L (measured horizontally), what is the horizontal distance between the point of intersection (PVI) and the highest point on the parabolic ve…

Accepted Answer

Introduction / Context: On a summit vertical curve formed by +g1% (up) and −g2% (down), the highest point occurs where the slope (grade) becomes zero. Knowing its location relative to the point of vertical intersection (PVI) is important for sight distance checks and profile detailing. Given Data / Assumptions: Parabolic vertical curve of total length L (PVC to PVT). Grades: +g1% approaching, −g2% leaving (g1, g2 > 0). Horizontal distances are used. Concept / Approach: Let x be the distance from the PVC to any point on the curve. For a simple parabola, the local grade at distance x is: G(x) = g1 − ((g1 + g2) / L) * x. At the highest point, G(x) = 0, so x_HP = g1 * L / (g1 + g2). The PVI lies midway in chainage between PVC and PVT, i.e., at L/2 from PVC. Therefore, the offset distance from PVI to the highest point equals |x_HP − L/2| = L * |g1 − g2| / (2 * (g1 + g2)). For a summit where g1 and g2 are positive magnitudes, we customarily write the algebraic expression as L * (g1 − g2) / (2 * (g1 + g2)), taking direction according to whether g1 > g2 or vice versa. Step-by-Step Solution: Write grade function: G(x) = g1 − ((g1 + g2)/L) * x.Set G(x) = 0 → x_HP = g1 * L / (g1 + g2) from PVC.Locate PVI at L/2 from PVC.Distance from PVI to highest point: |x_HP − L/2| = L * |g1 − g2| / (2 * (g1 + g2)). Verification / Alternative check: For a symmetric curve (g1 = g2), the formula gives zero, i.e., the highest point is exactly at the PVI projection, which is correct. Why Other Options Are Wrong: Option (b) inverts the numerator/denominator and does not reduce to zero for g1 = g2. Options (c) and (d) give the distance from PVC to the highest point, not from PVI to the highest point. Common Pitfalls: Confusing the distance from PVC with the offset from PVI; always check the reference point requested. Final Answer: L * (g1 - g2) / (2 * (g1 + g2))

Question 14

Curvature correction in precise levelling — if the horizontal distance L is in kilometres, what is the curvature correction (in millimetres) to apply to a staff reading?

Accepted Answer

Introduction / Context: Over long sights in levelling, the Earth’s curvature makes the line of sight diverge from the level surface. The staff reading at distance L therefore includes a curvature effect that must be corrected for precise work. A standard approximate formula expresses this correction in convenient units for field computations. Given Data / Assumptions: L is the sight length in kilometres. Only curvature is considered here (refraction is excluded). Small-angle approximations are acceptable for standard levelling distances. Concept / Approach: The curvature correction, C_c (meters), is approximately 0.0785 * L^2 when L is in kilometres. Expressed in millimetres, this is about 78.5 * L^2 mm; many texts round to 78.4 * L^2 mm. The correction is subtractive from the observed staff reading because the line of sight is above the level surface at the staff position. Step-by-Step Solution: Use C_c (m) ≈ 0.0785 * L^2.Convert to millimetres: C_c (mm) ≈ 78.5 * L^2.Standard rounding used in practice: 78.4 * L^2 mm.Apply with a negative sign to reduce the staff reading. Verification / Alternative check: Typical combined correction (curvature + refraction) is about 67.3 * L^2 mm; the difference confirms that 78.4 * L^2 mm corresponds to curvature alone. Why Other Options Are Wrong: 58.2/64.8/74.8 * L^2 mm: Do not match the standard curvature coefficient; some are closer to combined or unrelated rounded values. Common Pitfalls: Mixing curvature-only with combined curvature-and-refraction coefficients; always confirm which correction is being asked. Final Answer: 78.4 * L^2 mm

Question 15

Tape correction for pull — a 30 m standard steel tape (cross-section 15 mm × 1.0 mm) was standardized at 25°C under 30 kg pull. The base line was measured at the same temperature but with a 40 kg pull. Given E = 2.2 × 10^6 kg/cm^2, compute the pull …

Accepted Answer

Introduction / Context: A steel tape elongates when subjected to higher pull than its standardization tension. If not corrected, the measured distance will be underestimated, because each laid tape length is slightly longer than nominal. The pull correction quantifies this elastic extension using Hooke’s law. Given Data / Assumptions: Tape length, L = 30 m = 3000 cm. Cross-section area, A = 15 mm^2 = 0.15 cm^2. Standard pull, P0 = 30 kg; field pull, P = 40 kg → ΔP = P − P0 = 10 kg. Modulus of elasticity, E = 2.2 × 10^6 kg/cm^2. Temperature is unchanged (no thermal correction). Concept / Approach: Elastic extension ΔL under axial force follows ΔL = (ΔP * L) / (A * E), in consistent units. A positive ΔP means the tape is longer than standard, so the correction to the measured length is additive by +ΔL per tape length used. Step-by-Step Solution: Convert to consistent units: L = 3000 cm; A = 0.15 cm^2.Compute ΔL = (10 kg * 3000 cm) / (0.15 cm^2 * 2.2 × 10^6 kg/cm^2).Denominator = 0.15 * 2.2 × 10^6 = 330000; numerator = 30000.ΔL = 30000 / 330000 = 0.090909… cm = 0.00090909 m.Sign: + (tape lengthened) → add 0.000909 m to the measured distance per 30 m length. Verification / Alternative check: Sensitivity: If the pull were less than standard, the correction would be negative (tape shorter). Magnitude scales linearly with ΔP and L, and inversely with A and E. Why Other Options Are Wrong: + 0.0909 m: Off by a factor of 100 (centimetre vs metre conversion error). - 0.000909 m: Wrong sign; higher pull increases tape length. None of these: Incorrect, as + 0.000909 m is correct. Common Pitfalls: Unit mistakes between mm^2 and cm^2, and forgetting that correction is added when the tape is longer than standard. Final Answer: + 0.000909 m

Question 16

Prismatic compass — where is zero (0°) placed on the graduated circle?

Accepted Answer

Introduction / Context: Unlike surveyor’s compasses, the prismatic compass has a distinctive graduation system used to read bearings directly while sighting. Recognizing the position of zero and the clockwise graduation order helps avoid 90° misreads and ensures correct plotting. Given Data / Assumptions: Standard prismatic compass graduation is clockwise. Cardinal points correspond to specific degree values. Concept / Approach: In a prismatic compass, 0° is at the south end, 90° at the west, 180° at the north, and 270° at the east. Readings increase clockwise. This arrangement allows direct forward bearings when sighting through the prism while aligning the line of sight with the object. Step-by-Step Solution: Recall the standard layout: S = 0°, W = 90°, N = 180°, E = 270°.Confirm clockwise graduation.Therefore, zero is at the south end. Verification / Alternative check: Most instrument dials and textbooks illustrate the prismatic compass with this graduation; a quick look at a dial confirms the S-0° marking. Why Other Options Are Wrong: North/east/west ends do not carry 0° on the prismatic compass; they are at 180°, 270°, and 90° respectively. Common Pitfalls: Confusing prismatic with surveyor’s compass conventions; always check the instrument type before converting bearings. Final Answer: At the south end

Question 17

Magnetic declination — how does declination behave at a given place over time?

Accepted Answer

Introduction / Context: Magnetic declination is the horizontal angle between magnetic north and true north. Surveyors must account for it when converting magnetic bearings to true bearings and vice versa. Understanding its temporal behavior prevents systematic errors when older maps or bearings are reused. Given Data / Assumptions: Declination is influenced by Earth’s geomagnetic field and local anomalies. We are discussing the general trend over days to years. Survey adjustments often require epoch-specific values. Concept / Approach: Declination does not remain constant. It exhibits long-term secular variation (years to decades), annual changes, and short-term daily (diurnal) fluctuations. While these variations are typically gradual rather than abrupt, they are significant enough to require periodic updates from isogonic charts, models, or local observations. Therefore, the most accurate general statement is that declination varies with time and is not constant. Step-by-Step Solution: Recognize multiple time scales of variation: diurnal, seasonal, and secular.Conclude that a fixed declination value becomes outdated as time passes.Adopt practice: note epoch on maps and apply corrections for current year. Verification / Alternative check: Geomagnetic models (e.g., WMM/IGRF) are updated every 5 years, reflecting that declination changes measurably over time. Why Other Options Are Wrong: Remains constant: False in practice. Fluctuates: Partly true but incomplete; the broader statement “does not remain constant” captures all time scales. Changes abruptly: Not generally; changes are usually gradual. Common Pitfalls: Using declination values from old field books without updating to the present epoch. Final Answer: It does not remain constant (varies with time)

Question 18

Traverse Computations – Deflection Angle Between Consecutive Legs Using Reduced Bearings Given two consecutive traverse legs with bearings AB = N 52°45' E and BC = N 34°30' E (both as reduced bearings), determine the deflection at station B (state m…

Accepted Answer

Introduction: In plane traversing, the deflection angle at a station is the acute angle through which the direction of travel turns from one leg to the next, measured from the forward extension of the incoming tangent to the outgoing line, and designated as Right (R) or Left (L). Correctly interpreting reduced bearings is essential for consistent traverse adjustment and plotting. Given Data / Assumptions: Bearing of AB = N 52°45' E (first quadrant). Bearing of BC = N 34°30' E (first quadrant). Both are reduced bearings; deflection is the change in direction from AB to BC at B. Concept / Approach: When bearings lie in the same quadrant, the deflection is simply the numerical difference in their angles from the north line, with the sense determined by whether the second bearing rotates clockwise (Right) or counter-clockwise (Left) from the first. A smaller second bearing means turning toward the north line, i.e., a Left deflection. Step-by-Step Solution: Compute difference in magnitudes: 52°45' − 34°30' = 18°15'.Determine sense: from 52°45' down to 34°30' is a counter-clockwise turn ⇒ Left.State deflection: 18°15' L.Record at station B for plotting and computations. Verification / Alternative check: Consider limiting cases: if the two bearings were equal there would be zero deflection; if BC angle were larger, the turn would be Right. The present case matches a Left turn by the calculated difference. Why Other Options Are Wrong: Options with compass letters (E, N, W) are not deflection senses; “R” is incorrect because the rotation is toward the north line; only “L” with 18°15' matches the geometry. Common Pitfalls: Mixing whole circle and reduced bearings; forgetting to attach the correct sense (R/L) even with the right magnitude. Final Answer: 18° 15' L

Question 19

Survey Errors – Understanding Systematic Errors in Field Measurements Which statement best characterizes systematic errors in surveying observations and instruments, in contrast to random (accidental) errors?

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Introduction: Error analysis is central to reliable surveying. Systematic errors differ fundamentally from random errors: they follow known laws and hence can often be modeled and corrected. Identifying this distinction guides calibration, observation procedures, and error budgeting in traverse, levelling, and angle work. Given Data / Assumptions: Survey observations include random and systematic components. Examples: tape length error, collimation error, refraction, temperature expansion. Goal: select the most accurate characterization of systematic errors. Concept / Approach: Systematic errors have a known or knowable cause-and-effect relation (predictable sign and approximate magnitude). Because their behavior is understood, they are amenable to prevention (instrument adjustment) or correction (mathematical compensation). Random errors, by contrast, are unpredictable in sign and magnitude for individual observations but follow statistical laws collectively. Step-by-Step Solution: Identify hallmark: predictability based on physics/instrument characteristics.Conclude that “character is understood” succinctly captures systematic errors.Acknowledge that many systematic errors are cumulative unless corrected.Therefore option (b) is the most precise definition. Verification / Alternative check: Calibration reports (e.g., tape standardization) quantify systematics via constants and coefficients, confirming their predictable nature and enabling corrections. Why Other Options Are Wrong: (a) contradicts the essence of systematic errors; (c) is often true but describes a consequence rather than the defining trait—definitionally, “predictable/understood character” is primary; (e) describes random errors, not systematic ones; (d) is invalid. Common Pitfalls: Defining by effect (cumulative) rather than by cause (predictable law); assuming systematics always vanish without explicit correction. Final Answer: Errors whose character is understood (predictable behavior)

Question 20

Linear Measurement Methods – Which Gives Greater Accuracy Under Normal Conditions? Considering standard field practice and instrument capabilities, which method generally provides the highest accuracy in measuring linear distances?

Accepted Answer

Introduction: Linear measurement accuracy depends on the method and equipment. While tacheometry is fast and useful for topographic detail, its distance precision is limited by angular reading and staff intercept errors. Direct measurement with a properly standardized steel tape (and applied corrections) yields superior accuracy for baselines and control lines. Given Data / Assumptions: Ordinary field conditions (no EDM considered). Careful taping with temperature, pull, sag, and alignment corrections. Chaining refers to link-chain use, typically less precise than steel tapes. Concept / Approach: Direct steel-tape measurement minimizes intermediate computations and leverages instrument calibration. Systematic effects can be modeled and corrected, enabling sub-centimeter accuracy over tens of meters. Tachymetric distances, even with good instruments, rarely match high-grade taping due to compounding angular and staff reading uncertainties. Link chains further suffer from wear, kinks, and poor standardization compared to steel tapes. Step-by-Step Solution: Identify the hierarchy: taping > chaining > tacheometry for precision.Note correction capability in taping: length, temperature, sag, pull, slope.Conclude that direct taping (with corrections) is most accurate among the listed options.Select option (c). Verification / Alternative check: Specifications for baseline measurements prescribe steel tapes (or EDM) with detailed corrections, reflecting recognized superior accuracy over tachymetric methods. Why Other Options Are Wrong: (a) and (b) are generally less precise; (d) is false because methods are not equally accurate; (e) is the least accurate and used only for reconnaissance. Common Pitfalls: Overestimating tachymetric accuracy; neglecting tape standardization and correction application which are essential to realize the method’s potential. Final Answer: Direct steel-tape measurement (taping) with corrections

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