Surveying MCQ Quiz - Objective Question with Answer for Surveying - Download Free PDF

Concept: 

Least count = \(\frac{S}{n}\)

n → no. of divisions on vernier scale

s → smallest division of main scale

Calculation: 

s = 10’ = 10 minutes

L.C = 10” = \(\frac{{10'}}{{60}} = \frac{1}{{6}}\) minutes

\(\frac{1}{{6}} = \frac{{10}}{n}\)

n = 10 × 6

n = 60

Concept:

Prismatic compass:

• The graduated ring is attached to the needle and does not rotate with the line of sight.
• The graduations have 0 at S, 90° at W, 180° at N, and 270° at E.
• Graduations are engraved inverted since the graduated ring is read through the prism.
• The readings are taken with the help of a prism provided at the eye vane.
• Sighting and reading can be done simultaneously.
• The instrument can be held in hand also while making the observations.
• The eye vane consists of a metal vane with large silt.

Additional Information

• The graduations have 0 at N and S, 90° at  East and West in the surveyor compass.

Concept:

True difference is given by the following formula:

TD = (δh_PQ when instrument is at Q + δh_PQ when instrument is at P)/2

where,

TD = True Difference

δh_PQ = Apparent difference in elevation between P and Q

Calculation:

When the instrument is at P, apparent height difference = 2.123 - 1.543 = 0.58

When the instrument is at Q, apparent height difference = 1.750 - 1.121 = 0.629

So,

\(TD = \frac{{0.629 + 0.58}}{2} = 0.6045\)

Now, doing the adjustment,

When the instrument is at Q, staff reading at Q = 1.750

So, Adjusted reading = 1.750 - TD = 1.750 - 0.6045 = 1.1455 = 1.146 m

Concept:

Plane table survey:

A plane table surveying is a graphical method of surveying. In this method of surveying, field observation and plotting are done simultaneously helping the surveyor to compare the plotted details with actual features of the ground.

Advantages of Plane Table Survey:

• It is suitable for the location of details as well as contouring for large-scale maps directly in the field.
• As surveying and plotting are done simultaneously in the field, chances of getting omission of any detail get less.
• The plotting details can immediately get compared with the actual objects present in the field. Thus errors, as well as the accuracy of the plot, can be ascertained as the work progresses in the field.
• The plane table survey is generally more rapid and less costly than most other types of survey.

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Disadvantages of Plane Table Survey:

• The plane table survey is not possible in unfavorable climates such as rain, fog, etc.
• This method of survey is not very accurate and thus unsuitable for large scale or precise work.
• As no field book is maintained, plotting at different scale require full exercise.
• The quality of the final map depends largely on the drafting capability of the surveyor.

Important Points

The setting of Instruments:

• Fixing
• Leveling
• Centering

Different methods for plane table survey:

• Radiation
• Intersection
• Traversing 
• Resection

Explanation:

Plumb bob and plumb fork: 

• A plumbing fork is a hairpin-shaped brass frame made of arms of equal length.
• One is horizontal (upper arm) has a pointed end and is kept over the drawing sheet touching the plotted position of the instrument station while the other is inclined at a certain angle(lower arm) has a hook from which plumb bob is suspended as shown in the figure.

∴ Hence accurate centering of the plane table is done by using a plumbing fork.

Additional Information

Alidade: 

• It is an instrument used in plane table surveys.
• It is a wooden or brass ruler of about 50-60 cm in length. It is also known as the sight rule.
• Two vanes, the “object vane” and the “sight vane” are hinged at their two ends.

Spirit level (Bubble tube): 

• It is an instrument used in leveling.
• The glass tube containing the liquid and bubbles at a spirit level. In leveling, it is used to check the accuracy of the horizontal surface.

Important Points

The Basic surveying instruments required for plane table surveying are:

1. Plane table
2. Alidade for sighting (telescopic or simple)
3. Plumb bob and plumb fork
4. Compass
5. Spirit level
6. Chain
7. Ranging rods
8. Tripod
9. Drawing sheet and drawing tools

The different types of area measuring devices are as follows:

1. Clinometer or Inclinometer: It is used to measure angles of slopes either elevation or depression of an object with respect to gravity direction as reference.

2. Planimeter: It is the mechanical device used to measure area of plane. This measurement consists of dragging along boundary region.

Explanation:

Cadastral survey: Cadastral survey are made incident to the fixing of property lines, the calculation of land area, or the transfer of land property from one owner to another. They are also made to fix the boundaries of municipalities and of state and federal jurisdictions.

Topographical survey: This consist of horizontal and vertical location of certain points by linear and angular measurements and is made to determine the natural features of a country such as rivers, streams, lakes, woods, hills etc and such artificial features like roads, railways etc.

City survey: They are made in connection with the construction of streets, water supply systems, sewers and other works.

Topographical, cadastral and city survey are the parts of Land surveying.

Concept:

The correction due to the wrong alignment of the chain is given by

\({\rm{C}} = \frac{{{{\rm{d}}^2}}}{{2 \;\times\; {\rm{L}}}}\)

d - Difference in elevation due to the wrong alignment

L - The sloping length

l - True length

Correction due to the wrong alignment of the chain is always negative

 True length = Measured length - Correction

Calculation:

Given: d = 2 m, L = 50 m

\({\rm{C}} = \frac{{{{\rm{2}}^2}}}{{2 \;\times\; {\rm{50}}}}\)

⇒ C = 0.04

True length (l) = 50 - 0.04 = 49.96 m​.

Concept:

The precision of leveling is ascertained according to the error of closure. The permissible limit of closing error depends upon the nature of the work for which the leveling is to be done. The permissible closing error may be expressed as, \(\text{E} = \text{C}\times\sqrt{D}\)

Where,

E = the error in metres,

C = the constant, the value of which depends upon the type of instrument, nature of the country, atmospheric conditions and care and judgement of the level man  

D = distance in kilometre

• Rough levelling: \(\text{E} = \pm\text{0.100}\times\sqrt{D}\)
• Ordinary levelling: \(\text{E} = \pm\text{0.025}\times\sqrt{D}\)
• Accurate levelling: \(\text{E} = \pm\text{0.012}\times\sqrt{D}\)
• Precise levelling: \(\text{E} = \pm\text{0.006}\times\sqrt{D}\)

Explanation:

Given Link length = \(2\frac{1}{16}\) ft

Chain has 16 Links ⇒ Total Length = 16 × \(2\frac{1}{16}\) = 33 ft

Revenue Chain:

The revenue chain is 33 ft long and consists of 16 links. 

Additional InformationThese chains are mainly used for measuring field in cadastral survey.

Concept:

Dip:

• It is the inclination of the magnetic needle with the horizontal. The dip is zero at the equator and the needle will remain horizontal.
• At a place near 70° north latitude and 96° west longitude, the dip will be 90°. This area is called the magnetic north pole. Similarly, near the south magnetic pole, the dip is 90°.

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Declination: 

• It is the angle between the magnetic and geographic meridians or the angle in the horizontal plane between magnetic north and true north.

Explanation:

Explanation:

The difference (degree) in the magnitude of the fore bearing and back bearing of any line is 180° or if the difference is exactly 180°, the two stations may be considered as not affected by local attraction.

For regular hexagon, Sum of interior angles = (n - 2)180° 

Sum of interior angles = (6 - 2)180° = 720° 

Each interior angle = \(\frac{720}{6}\) = 120° 

Back bearing = 180° + Fore bearing = 180° + 36°45' = 216°45'

∴ Fore bearing of BC = 216°45' - 120° = 96°45'

Explanation:

Leveling staff:

• It is a self-reading graduated wooden rod having a rectangular cross-section. The lower end of the rod is shod with metal to protect it from wear and usually point of zero measurements from which the graduations are numbered.
• Staff are either solid (having a single piece of 3-meter height)  or folding staff (of 4-meter height into two or three pieces)
• The least count of a leveling staff is 5 mm.
• Leveling used with a leveling instrument to determine the difference in height between points or heights of points above a vertical datum.

Important Points

Due earth refraction, line of sight bends towards the earth, therefore we noted less value of staff of reading i.e. Decrease in staff reading. To understand this refers the following figure:

Instrument

SR₁ = Staff reading without refraction

SR₂ = staff reading with refraction (Noted value)

It is clear from above that: SR₂ < SR₁

∴ Staff reading reduces due to refraction.

Important Point:

Concept:

Vernier Scale is used to measure the fractional part of the least division marked on the main scale.

Types of Vernier Scale

• Direct Vernier:
  • N divisions of the direct vernier = (N - 1) division of the main scale
• Retrograde Vernier:
  • N divisions of the retrograde vernier = (N + 1) division of the main scale
• Extended Vernier:
  • N divisions of the extended vernier = (2 N - 1) division of the main scale

Calculation:

N divisions of the extended vernier = (2 N - 1) division of the main scale

8 divisions of the extended vernier = (2 × 8 - 1) division of the main scale