Diploma Civil and Mechanical Engineering for Engineering Assistant · Chapter 10

Drawing and Survey for VRO/Surveyor (with Land-Revenue Basics)

What to remember

Survey fixes the relative positions of points on the ground; chain survey uses only linear measurements, compass survey adds bearings, levelling finds heights, plane tabling draws the map in the field.
Representative Fraction (RF) = length on drawing / actual length (same units); the Gunter's chain is 66 ft with 100 links, and 1 acre = 4840 sq yd = 40 guntas.
In village land records, the Adangal/Pahani records crops and possession, the 1-B register records ownership, and the FMB (Field Measurement Book) holds the sketch and area of each survey number.

Basics of drawing

Engineering drawing is the language of the engineer. A drawing must be clear, to scale and follow standard practice. Drawing sheets follow the A-series: A0 is 841 × 1189 mm (area about 1 sq m); each next size (A1, A2, A3, A4) is half the previous one by cutting along the longer side. A4 is 210 × 297 mm.

Pencils are graded: H, 2H (hard, for construction lines), HB, F (medium), B, 2B (soft, for dark lines). Basic tools are the drawing board, T-square, set squares (45° and 30°–60°), compass, divider, scale, protractor and French curves.

Types of lines (conventional):

Continuous thick: visible outlines and edges.
Continuous thin: dimension lines, extension lines, hatching.
Dashed (medium): hidden edges.
Chain thin (long dash and dot): centre lines.
Chain thick at ends: cutting plane.

Dimensioning: figures are written above the dimension line, with arrowheads touching the extension lines. Dimensions are not repeated and are given in one unit (usually mm).

Orthographic projection shows an object by views on mutually perpendicular planes: front view (elevation), top view (plan) and side view. In first angle projection (used in India), the object lies between the observer and the plane, so the plan comes below the elevation. In third angle projection the plane is between the observer and the object.

Scales

A scale reduces (or enlarges) a real length to drawing size.

Type	Reads	Use
Plain scale	two units (e.g. metre and decimetre)	simple maps
Diagonal scale	three units (e.g. m, dm, cm)	fine measurement
Vernier scale	very small parts of the smallest division	instruments
Scale of chords	angles	drawing angles

RF has no unit. Example: 1 cm on paper = 5 m on ground, so RF = 1 cm / 500 cm = 1/500. Length of scale = RF × maximum length to be measured. Area scales as the square of RF: on a 1/500 map, 1 sq cm = 25 sq m.

Chain survey

Chain survey is used for small, fairly flat areas with simple detail. The area is divided into well-shaped triangles (the base line is the longest line; check lines test the work).

Instruments: chain or tape, ranging rods (usually 2 m or 3 m, painted in alternate 20 cm bands of black and white or red and white), arrows (set of 10), pegs, cross staff, optical square, plumb bob.

Chain	Length	Links	Link length
Metric chain	20 m (also 30 m)	100 (for 20 m)	0.2 m
Gunter's chain	66 ft	100	7.92 in
Engineer's chain	100 ft	100	1 ft

Terms: offset is the lateral measurement from the survey line to a detail (perpendicular offset or oblique); ranging is fixing intermediate points in a straight line; tie line and check line control accuracy. Obstacles: if a pond blocks the line, use the offset or triangle method. Corrections: if the chain is too long, the measured distance is too short, so the true length is greater than the measured length (true length = measured × L'/L).

Compass survey

The prismatic compass measures bearing: the horizontal angle of a line from the north direction.

Whole Circle Bearing (WCB): 0° to 360° clockwise from north.
Quadrantal Bearing (QB): angle from the nearest north or south, e.g. N 30° E.
Back bearing = fore bearing ± 180°. Example: fore bearing 65°30' gives back bearing 245°30'.
Magnetic declination is the angle between true and magnetic meridians. Local attraction is the disturbance by iron, steel or electric lines; it is found when fore and back bearings do not differ by exactly 180°.
Included angle of a closed traverse: sum of interior angles = (2n − 4) × 90°. A pentagon (n = 5) has 540°.

Levelling

Levelling gives the height (reduced level, RL) of points. Instruments: dumpy level or auto level, levelling staff, tripod. Terms:

Backsight (BS): first staff reading after setting up; Foresight (FS): last reading before shifting; Intermediate sight (IS): any reading between.
Change point (turning point): where both FS and BS are taken.
Height of instrument (HI) = RL of benchmark + BS. RL of a point = HI − FS (or IS).
Benchmark (BM) is a fixed point of known RL; the Great Trigonometrical Survey benchmarks are the permanent ones.

Two reduction methods: HI (height of collimation) and Rise and Fall. In rise and fall, if the next reading is smaller, it is a rise. Arithmetic check: ΣBS − ΣFS = Σrise − Σfall = last RL − first RL.

Example: ΣBS = 5.20 m, ΣFS = 3.10 m, first RL = 100.00 m, so last RL = 102.10 m.

Contours join points of equal elevation. Properties: contours never cross (except in an overhanging cliff or a cave); closely spaced contours show a steep slope; widely spaced contours show a gentle slope; equal spacing shows uniform slope; a closed contour shows a hill or a depression; V-shapes pointing to the higher ground show a valley; V-shapes pointing to the lower ground show a ridge.

Plane table and theodolite

Plane table survey plots the map in the field. Parts: drawing board, tripod, alidade, spirit level, plumbing fork, trough compass. Orientation keeps the table in the same direction at every station. Methods: radiation, intersection, traversing and resection. Resection fixes the table's own position (the two-point and three-point problems).

The theodolite measures horizontal and vertical angles. A transit theodolite can rotate its telescope fully about the horizontal axis. Face left and face right readings are averaged to remove instrument errors. A total station adds electronic distance measurement.

Area calculation: trapezoidal rule A = d × [(O₁ + Oₙ)/2 + O₂ + … + Oₙ₋₁]; Simpson's rule needs an odd number of ordinates (even number of strips).

Instrument	Measures	Main use
Chain / tape	distance	small flat areas
Prismatic compass	bearing	traverse
Level	height difference	RL, contours
Plane table	map directly	quick small maps
Theodolite	angles	accurate traverse

Land-revenue basics (Andhra Pradesh)

AP follows the ryotwari system, where the cultivator (ryot) pays land revenue directly to the State. The village officer maintains the records and, in the Sachivalayam system, the Village Revenue Officer (VRO) is the village-level revenue official.

Area units: 1 acre = 4840 sq yd = 43,560 sq ft = 40 guntas; 1 gunta = 121 sq yd (1089 sq ft); 1 hectare = 2.47 acres; in local use 100 cents = 1 acre, so 1 cent = 48.4 sq yd.

Record	Purpose
Adangal / Pahani	field-wise crops, possession and irrigation source each season
1-B register	owner-wise land holding (Record of Rights)
FMB (Field Measurement Book)	sketch, dimensions and area of each survey number
Village map (tracing)	boundaries of all survey numbers in a village
Pattadar passbook / title deed	ownership document given to the pattadar
Mutation	change of the name in records after sale, gift or inheritance

Survey number identifies a parcel; sub-division splits it (e.g. 45/1, 45/2). Land is classed as wet (irrigated) and dry. Web-based records (Meebhoomi) let citizens see the Adangal and 1-B online. Disputes are resolved by the Tahsildar and revenue officers, and a licensed surveyor carries out the measurement.

Exam traps

RF is a pure ratio (no unit); do not write "1 cm".
Back bearing = fore bearing ± 180°, not ± 90°.
Rise and fall check includes ΣBS − ΣFS, not ΣBS + ΣFS.
A chain that is too long reads the distance too short.
Plain scale: two units; diagonal scale: three units.
1 gunta is 121 sq yd; 1 cent is 48.4 sq yd.
Adangal records crops; 1-B records ownership.
First angle projection: plan below elevation; third angle: plan above.

One-liners

1. Gunter's chain: 66 ft, 100 links.
2. Metric chain commonly used: 20 m.
3. A0 sheet: 841 × 1189 mm.
4. 1 acre = 40 guntas = 4840 sq yd.
5. 1 hectare = about 2.47 acres.
6. Ranging rods are painted in alternate bands.
7. HI = RL of BM + BS.
8. Closed traverse interior angle sum = (2n − 4) × 90°.
9. Contours close together mean steep slope.
10. A theodolite measures horizontal and vertical angles.
11. Back bearing of 120° is 300°.
12. FMB records the area and sketch of a survey number.

Practice questions

A drawing is made so that 1 cm on paper represents 5 m on the ground. The representative fraction is
1. 1/5
2. 1/5000
3. 1/50
4. 1/500
Answer
D. 1/500
5 m = 500 cm, so RF = 1/500.
The fore bearing of a line is 65°30'. Its back bearing is
1. 245°30'
2. 335°30'
3. 155°30'
4. 115°30'
Answer
A. 245°30'
Back bearing = fore bearing + 180° = 245°30'.
The sum of interior angles of a closed pentagonal traverse is
1. 450°
2. 540°
3. 360°
4. 720°
Answer
B. 540°
(2n - 4) x 90° = 6 x 90° = 540°.
Benchmark RL is 100.00 m and the backsight is 1.50 m. The height of instrument is
1. 101.50 m
2. 150.00 m
3. 98.50 m
4. 100.15 m
Answer
A. 101.50 m
HI = RL + BS = 100.00 + 1.50 = 101.50 m.
With HI = 101.50 m, a foresight of 2.30 m gives a reduced level of
1. 103.80 m
2. 99.20 m
3. 98.20 m
4. 101.50 m
Answer
B. 99.20 m
RL = HI - FS = 101.50 - 2.30 = 99.20 m.
The sum of backsights is 8.40 m and the sum of foresights is 6.15 m. If the first RL is 50.00 m, the last RL is
1. 47.75 m
2. 56.15 m
3. 48.55 m
4. 52.25 m
Answer
D. 52.25 m
Last RL = first RL + (ΣBS - ΣFS) = 50.00 + 2.25 = 52.25 m.
A farmer owns 3 acres. How many guntas is this?
1. 3 x 4840
2. 121
3. 120
4. 90
Answer
C. 120
1 acre = 40 guntas, so 3 acres = 120 guntas.
On a map of scale 1:500, a plot measures 4 cm by 5 cm. Its actual area is
1. 200 sq m
2. 500 sq m
3. 100 sq m
4. 2000 sq m
Answer
B. 500 sq m
4 cm = 20 m and 5 cm = 25 m; area = 500 sq m.
For a scale of RF 1/50, the length of scale needed to read a maximum of 5 m is
1. 10 cm
2. 25 cm
3. 5 cm
4. 50 cm
Answer
A. 10 cm
Length of scale = RF x max length = 500 cm / 50 = 10 cm.
How many square feet are there in 2 guntas?
1. 2420
2. 4356
3. 2178
4. 1089
Answer
C. 2178
1 gunta = 121 sq yd = 1089 sq ft; 2 guntas = 2178 sq ft.
12 cents of land (1 cent = 48.4 sq yd) equals
1. 1210 sq yd
2. 484 sq yd
3. 4840 sq yd
4. 580.8 sq yd
Answer
D. 580.8 sq yd
12 x 48.4 = 580.8 sq yd.
The sum of interior angles of a closed hexagonal traverse is
1. 900°
2. 1080°
3. 720°
4. 540°
Answer
C. 720°
(2 x 6 - 4) x 90° = 720°.
Using the trapezoidal rule with strip width 10 m and ordinates 2, 3, 4, 3, 2 m, the area is
1. 120 sq m
2. 140 sq m
3. 100 sq m
4. 160 sq m
Answer
A. 120 sq m
A = 10 x [(2+2)/2 + 3 + 4 + 3] = 10 x 12 = 120 sq m.
A 2 ha field equals about how many acres?
1. 2.47
2. 4.94
3. 9.88
4. 0.81
Answer
B. 4.94
1 ha is about 2.47 acres, so 2 ha is about 4.94 acres.
The length of a Gunter's chain is
1. 20 m
2. 100 ft
3. 30 m
4. 66 ft
Answer
D. 66 ft
Gunter's chain is 66 ft with 100 links.
The length of each link of a 20 m metric chain is
1. 0.2 m
2. 0.1 m
3. 0.02 m
4. 0.3 m
Answer
A. 0.2 m
20 m / 100 links = 0.2 m.
Which register in an Andhra Pradesh village records crops grown and possession season by season?
1. Village map
2. FMB
3. 1-B register
4. Adangal
Answer
D. Adangal
The Adangal (Pahani) is the crop and possession record.
The Field Measurement Book (FMB) contains
1. only the crop details
2. the tax receipts of the village
3. the list of village employees
4. a sketch and area of each survey number
Answer
D. a sketch and area of each survey number
FMB holds the field sketch, dimensions and area of every survey number.
Which register records the owner-wise holdings (Record of Rights)?
1. Crop booking register
2. Adangal
3. 1-B register
4. Village sketch
Answer
C. 1-B register
The 1-B is the ownership (RoR) record.
The land tenure system followed in Andhra Pradesh, where the cultivator pays revenue directly to the State, is
1. Mahalwari
2. Ryotwari
3. Zamindari
4. Jagirdari
Answer
B. Ryotwari
Ryotwari settles directly with the ryot.
A ranging rod is normally painted in alternate bands of
1. 1 m each
2. 50 cm each
3. 20 cm each
4. 5 cm each
Answer
C. 20 cm each
Standard bands are 20 cm.
The longest line of a chain survey network, running through the area, is called the
1. offset line
2. base line
3. check line
4. tie line
Answer
B. base line
The base line is the main and longest line; check lines test accuracy.
A line is run between two stations only to test the accuracy of the work. It is a
1. check line
2. ranging line
3. base line
4. offset
Answer
A. check line
Check lines verify the measured triangles.
If the chain used is longer than its standard length, the measured distance is
1. equal to the true distance
2. unaffected
3. less than the true distance
4. more than the true distance
Answer
C. less than the true distance
A long chain covers more ground per chain length, so fewer lengths are counted and the reading is smaller than the true distance.
The horizontal angle of a line from the magnetic north, measured clockwise from 0° to 360°, is
1. whole circle bearing
2. declination
3. dip
4. quadrantal bearing
Answer
A. whole circle bearing
This is WCB.
Disturbance of the magnetic needle by nearby iron or steel is called
1. magnetic declination
2. local attraction
3. parallax
4. dip
Answer
B. local attraction
Local attraction shows up as fore and back bearings not differing by 180°.
The angle between the true meridian and the magnetic meridian is
1. local attraction
2. dip
3. azimuth
4. magnetic declination
Answer
D. magnetic declination
This angle is the declination.
A reading taken on a staff held on a point of known RL is a
1. intermediate sight
2. backsight
3. foresight
4. change point
Answer
B. backsight
The first reading after setting up on a known RL point is the backsight.
Which readings are taken at a change point?
1. Only an intermediate sight
2. Only a backsight
3. Only a foresight
4. Both a foresight and a backsight
Answer
D. Both a foresight and a backsight
A change point carries the FS from one setup and the BS of the next.
The arithmetic check in the rise and fall method is
1. ΣBS - ΣFS = Σrise - Σfall = last RL - first RL
2. ΣBS = ΣFS
3. ΣBS + ΣFS = Σrise + Σfall
4. ΣIS = ΣFS
Answer
A. ΣBS - ΣFS = Σrise - Σfall = last RL - first RL
These three differences must agree.
Contour lines drawn very close together indicate
1. a flat plain
2. a gentle slope
3. a steep slope
4. a lake
Answer
C. a steep slope
Close spacing means rapid change in elevation.
Which statement about contours is correct?
1. Two contours of different elevations do not cross except at an overhanging cliff
2. Contours always cross at ridges
3. A contour can end suddenly in the middle of a map
4. Contours of different heights can merge on flat ground
Answer
A. Two contours of different elevations do not cross except at an overhanging cliff
Contours cannot cross, except in rare overhangs or caves.
Contour V-shapes pointing toward lower ground indicate a
1. pond
2. ridge
3. plateau
4. valley
Answer
B. ridge
V-shapes pointing downhill show a ridge; pointing uphill show a valley.
The process of keeping the plane table in the same direction at every station is
1. resection
2. radiation
3. levelling
4. orientation
Answer
D. orientation
Orientation keeps lines parallel to their ground positions.
Fixing the position of the table station by sighting to known points is
1. traversing
2. radiation
3. resection
4. intersection
Answer
C. resection
Resection locates the instrument station.
Which instrument measures both horizontal and vertical angles?
1. Dumpy level
2. Theodolite
3. Chain
4. Prismatic compass
Answer
B. Theodolite
The theodolite measures both.
In first angle projection, the plan is placed
1. below the elevation
2. above the elevation
3. behind the elevation
4. left of the elevation
Answer
A. below the elevation
In first angle projection, the plan is drawn below the front view.
In engineering drawing, hidden edges are shown by
1. continuous thick lines
2. chain thin lines
3. wavy lines
4. dashed lines
Answer
D. dashed lines
Hidden edges use dashed lines.
The size of an A4 drawing sheet is
1. 594 x 841 mm
2. 148 x 210 mm
3. 210 x 297 mm
4. 297 x 420 mm
Answer
C. 210 x 297 mm
A4 is 210 x 297 mm.
Consider the statements about scales. 1. A plain scale reads two units. 2. A diagonal scale reads three units. Which is/are correct?
1. 1 only
2. 2 only
3. Both 1 and 2
4. Neither 1 nor 2
Answer
C. Both 1 and 2
Plain scale: two units; diagonal scale: three.
Consider the statements. 1. The Adangal records ownership only. 2. The FMB shows the area of each survey number. Which is/are correct?
1. 1 only
2. Both 1 and 2
3. 2 only
4. Neither 1 nor 2
Answer
C. 2 only
Adangal records crops and possession; FMB holds the sketch and area.
Consider the statements. 1. Back bearing = fore bearing ± 180°. 2. A closed traverse's interior angle sum is (2n - 4) x 90°. Which is/are correct?
1. 1 only
2. Both 1 and 2
3. 2 only
4. Neither 1 nor 2
Answer
B. Both 1 and 2
Both are standard results.
Consider the statements. 1. RF has the unit of cm. 2. Area on a map scales with the square of the RF. Which is/are correct?
1. 2 only
2. 1 only
3. Both 1 and 2
4. Neither 1 nor 2
Answer
A. 2 only
RF is a unitless ratio; area scales as the square.
Change of the name of the holder in land records after sale or inheritance is called
1. resection
2. contouring
3. ranging
4. mutation
Answer
D. mutation
This is mutation.
A parcel of land is split into 45/1 and 45/2. This is an example of a
1. change point
2. benchmark
3. check line
4. sub-division of a survey number
Answer
D. sub-division of a survey number
Sub-divisions of a survey number take suffixes.

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