ASRB NET — Farm Machinery & Power / Land & Water Management Engineering / Agricultural Structures & Process Engineering · India · Agricultural Scientists Recruitment Board (ICAR)
Original practice questions written to the published syllabus · not past papersMeasuring land, levels and volumes, from chain survey to total station and GNSS, and designing land grading.
In the exams: GATE AG Section 4 (surveying asked in 7 of 8 papers 2019–26); ICAR AIEEA-PG Unit VII; TNPSC Unit I; RPSC AAE Unit 1; NCEES PE surveying
How our questions for ASRB NET spread across the units of Surveying & Levelling. Difficulty: 1 easy, 8 medium, 21 hard.
| Land grading and levelling design | 7 | |
| Levelling: rise-and-fall and height-of-instrument methods | 3 | |
| Reciprocal levelling | 3 | |
| Theodolite traversing and closing error | 3 | |
| GPS/GNSS surveying | 3 | |
| Chain and tape surveying, including tape corrections | 2 | |
| Contouring | 2 | |
| Total station | 2 | |
| Earthwork volume computation | 2 | |
| Compass traversing and bearings | 1 | |
| Plane table surveying | 1 | |
| Computation of area: trapezoidal and Simpson's rules | 1 |
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
When the bubble of a level was moved through 4 divisions, the staff reading at 80 m changed by 0.012 m. What is the sensitivity of the bubble tube per division?
A. 7.7 seconds
α = 206,265 × s/(nD) = 206,265 × 0.012/(4 × 80) = 7.7″ per division. Forgetting to divide by the number of divisions gives 30.9″; multiplying by n gives 123.8″; 7.7 minutes has the right number with the wrong unit.
Further reading: Punmia, Jain and Jain, Surveying Vol. I
A staff is read from a level. The staff reading is 3.000 m when held vertical, but the staff was actually tilted 3° from the vertical in the direction of sight. What reading was observed (to 3 decimals), and what is the lesson?
C. 3.004 m; a tilted staff always reads too high
The horizontal line cuts the tilted staff at a graduation of 3.000/cos 3° = 3.004 m. Tilt in any direction increases the reading, which is why the staffman rocks the staff and the minimum reading is taken.
Further reading: Punmia, Jain and Jain, Surveying Vol. I
A level set at A reads 1.250 m on a staff at a point B 2.4 km away. Correcting for curvature and refraction (0.0673d² m, d in km), what is the corrected staff reading at B?
B. 0.862 m
Correction = −0.0673 × 2.4² = −0.3876 m, so corrected reading = 1.250 − 0.3876 = 0.862 m. The observed reading is too large because the level surface curves away below the horizontal line of sight; adding the correction is the sign slip. 0.798 m applies curvature alone (0.0785d²); 1.088 m forgets to square d; 1.638 m adds the correction.
Further reading: Punmia, Jain and Jain, Surveying Vol. I
Reservoir areas enclosed by contours at 100, 102, 104, 106 and 108 m are 1200, 2600, 4100, 5900 and 8000 m². What is the storage between 100 m and 108 m by the prismoidal formula?
D. 34267 m³
Prismoidal: V = (d/3)[(A1 + A5) + 4(A2 + A4) + 2A3] = (2/3)[9200 + 4 × 8500 + 2 × 4100] = 34267 m³. The trapezoidal formula gives 34400 m³; swapping the 4 and 2 weights is a common slip; using d = 4 m double-counts. Using d = 4 m gives 68533 m³; swapping the weights gives 28400 m³.
Further reading: Punmia, Jain and Jain, Surveying Vol. I
The transit rule for balancing a traverse is preferred over Bowditch's rule when
D. angles are measured more precisely than distances
The transit rule distributes corrections in proportion to the size of each latitude and departure, which assumes angles are good and lengths poorer (theodolite with tape). Bowditch assumes equal effect of angular and linear errors and is the usual rule for compass traverses. Neither can be applied to an open traverse.
Further reading: Punmia, Jain and Jain, Surveying Vol. I
An RTK GNSS survey gives an ellipsoidal height of 18.6 m at a point where the geoid undulation N from the geoid model is −52.3 m. What is the orthometric height (height above the geoid)?
C. 70.9 m
H = h − N = 18.6 − (−52.3) = 70.9 m. Where the geoid lies below the ellipsoid (negative N), orthometric heights exceed ellipsoidal heights. Adding N gives -33.7 m; using the ellipsoidal height as if it were above mean sea level is the classic mistake.
Further reading: Ghilani and Wolf, Elementary Surveying
Six offsets of 2.0, 3.5, 4.2, 3.9, 3.0 and 2.4 m are taken at 10 m intervals. Using Simpson's rule for the first five ordinates and the trapezoidal rule for the last strip, what is the total area?
A. 170.33 m²
Simpson on O1–O5: (10/3)[2.0 + 3.0 + 4(3.5 + 3.9) + 2(4.2)] = 143.33 m². Last strip: 10(3.0 + 2.4)/2 = 27.00 m². Total = 170.33 m². Forcing Simpson onto six ordinates gives 161.33 m², which is invalid; trapezoidal throughout gives 168.00 m².
Further reading: Punmia, Jain and Jain, Surveying Vol. I
When is the plane method of land-grading design NOT the best choice?
A. On fields so irregular that a single plane would require excessive earth movement
A single best-fit plane is efficient for fairly uniform fields; where the surface is strongly irregular, profile, plan-inspection or contour-adjustment methods allow varying grades and cut far less earth.
Further reading: Schwab et al., Soil and Water Conservation Engineering
Which is a well-documented agronomic drawback of deep cuts in land grading, and how is it usually managed?
A. Cut areas expose less fertile subsoil and can yield less for some seasons; minimise cut depth and apply organic matter or fertiliser to cut areas
Removing topsoil exposes subsoil lower in organic matter and nutrients, and crops on cut patches often lag until fertility is rebuilt. Designs minimise earth moved, and cut areas receive manure or fertiliser. The other options are not general truths.
Further reading: Schwab et al., Soil and Water Conservation Engineering
Which statement about contour lines is FALSE?
B. Contours of different elevations can merge into a single line on a gentle slope
Contours of different elevations merge only at a vertical cliff and cross only at an overhang; on a gentle slope they are widely spaced, never merged. The other three statements are standard characteristics.
Further reading: Punmia, Jain and Jain, Surveying Vol. I
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