Surveying interview Questions & Answers
The conceptual knowledge of Surveying is very important and necessary for Civil engineering works. Because it is the starting point for any engineering project. Surveys are required before and during the planning and construction of engineering projects. Hence the knowledge of surveying has become essential for a Civil engineer.
So, if you are looking for surveying questions that are mostly asked during an interview, then you will find those questions, answered with good explanations in this article.
What is Surveying?
The method of taking measurements to determine the relative positions of points on the surface of the earth.
What is the object of surveying?
The object of surveying is to prepare a map that is drawn to some suitable scale. These maps are made to represent the relative positions of objects or points on the surface of the earth.
What is the plane surveying?
When the area of the surveying is less than 250 km², the curvature of the earth is not considered. So then in that case the earth’s surface is assumed as a plane surface. Hence this type of surveying is known as plane surveying.
What is geodetic surveying?
When the area of the surveying is greater than 250 km², the curvature of the earth is considered. So then in that case the earth’s surface is assumed as a curved surface. Hence this type of surveying is known as geodetic surveying.
What are the basic differences between geodetic surveys and plane surveys?
(i) The curvature of the earth is not considered in plane surveying but in geodetic surveying curvature of the earth is considered.
(ii) Plane surveying method is adopted when the area is less than 250 km². But when the area is more than 250 km², the geodetic surveying method is adopted.
What are the objects of surveying?
(i) to work from the whole to part (this is followed in order to reduce the errors)
(ii) to establish a new station by taking at least two references (linear and angular measurements) from fixed points.
What is a Reconnaissance survey?
This is also known as the preliminary survey. This is a preliminary study of an area that might be used for a construction scheme such as for a road or railways project. It helps to determine the probable framework of surveying work to be adopted.
What is an archaeological survey?
An archaeological survey collects information about the location, distribution, and ancient human cultures and about relic structures.
What is the purpose of cadastral survey?
A cadastral survey is related to land ownership, measurement, and delineation of the boundary of properties.
What is a Topographical survey?
The topographical survey helps determine the natural features (i.e., topography) of a country. This technique of survey is used to identify and plot the contours of the ground surface and also existing features on the surface of the earth or below the surface of earth or above the surface of the earth.
What is catenary in chain survey?
When a chain or a tape is suspended from each end, it forms a curve which is called a catenary.
What do you know by normal-tension?
The tension at which the measured distance is equal to the measured distance in the case of chaining is known as normal tension. Actually, in normal tension, sag correction is neutralized by pull correction.
Why sag correction is always negative?
When a chain or tape is suspended during measurements, it forms a curve called a catenary due to its self-weight. Because of this, the curve is longer than the straight-line distance between the ends of the chain or tape. Thus the tape or chain reads longer than the actual distance. So the error in this condition is positive in nature. That’s Why it is corrected by sag correction which is negative in nature.
In a chaining surveying operation, who is the leader and who is the follower?
The person at the forward end of the chain who drags the chain is known as the leader. The person at the rear end of the chain is known as the follower.
What do you mean by RF?
The ratio of the length on the drawing to the corresponding actual length of the object is known as RF.
What is the basic difference between the diagonal scale and the plain scale?
On a plain scale, two consecutive units (e.g, cm & mm) can be measured. But in the case of a diagonal scale, three consecutive units can be measured.
How many ranging rods are required to range a survey line?
For direct ranging at least three ranging rods are required. In the case of indirect ranging at least four ranging rods are required.
What is the length of one link in a metric chain?
The 20 m metric chains are divided into 100 links. So one link is 0.2m, i.e., 20cm long.
The 30 m metric chains are divided into 150 links. So one link is 0.2m, i.e., 20cm long.
What is the length of the Gunter’s chain?
It is 66ft long. This chain is divided into 100 links so each link is 0.66ft long.
What is the length of the Revenue chain?
33 ft length and 16 links. It is mainly used in cadastral surveying.
What is the length of the Engineers chain?
100 ft length, 100 links, each link is 1 ft.
Which type of chain is used when greater accuracy is needed?
The steel band is used when more accuracy is required. The width of the ribbon of the steel band is 16 mm and the length is 20 or 30 m.
What is invar tape?
Invar tape is made of alloy metal. steel 64 % and nickel 36%. Its thermal coefficient is very low, that’s why it is not affected by the change in temperature. It is used when maximum precision is required.
What are the advantages of steel band?
Advantages: (a) very light and easy to open or fold, (b) maintain their standard length even after continuous use, (c) self-weight is less, so they sag slightly.
What are the advantages of chains?
Advantages: (a) can be used easily and quickly, (b) can withstand wear and tear, and (c) can be easily repaired in the field.
What is pacing or stepping?
For reconnaissance surveys, distances are often measured by counting the number of walking steps of a person. The walking step of a person is considered as 2.5ft or 80 cm.
What are the advantages of chain surveys?
(i) small area (ii) open and level ground with simple details (iii) large-scale maps.
What is the method referred to in chain surveying?
The method followed in chain surveying is triangulation. In this method, the total area is divided into a network of triangles, preferably well-conditioned triangles. The sides of the triangles are measured with a tape or chain. No angular measurements are taken in the chain survey.
What is a well-conditioned triangle?
A triangle with no angles is less than 30° and more than 120°.
What is an ill-conditioned triangle?
A triangle with any of its angles less than 30° and greater than 120°.
What is an offset?
The lateral measurements of the objects to the right or left of a chain line.
What are the types of offsets in chain surveying?
According to direction two types of offsets are there -(i) perpendicular offset and (ii) oblique offset.
According to length two types of offsets are there- (i) short offset and (ii) long offset.
What is the limiting length of an offset?
The limiting length of an offset is 15m.
What is the baseline?
The longest line through the center of the field is on a level ground unobstructed on which the framework of the triangle is built-up in case of chain surveying.
What is the main survey line?
The line joining the main survey stations is called the main survey line. Main survey lines form the boundary of the area.
What is used after every chain length measured on the ground?
An arrow is inserted into the ground after each chain length is measured. These are made of tempered steel wire 4 mm in diameter. One end of the arrow is pointed and the other end is bent into a ring of a diameter of 50 mm. The overall length is 400 mm. These are used for counting the number of chains while measuring a chain line.
What type of ranging method is adopted if both ends of surveying lines are visible?
Direct ranging is done when both ends of a survey line are mutually intervisible.
What type of ranging method is adopted if both ends of surveying lines are not visible?
Indirect ranging or reciprocal ranging is done when both ends of a survey line are not mutually intervisible.
What is the check line or the proof line?
The check lines are taken to check the accuracy of the framework. These are the lines joining the apex of the triangle to some fixed points on the opposite side and also the line joining the two fixed points on any two sides of the triangle.
What is the tie line?
A line joining the fixed point on the two sides of a triangle to locate interior details which are far away from the main survey line and to check the accuracy of the framework of the triangle.
What is the index map in surveying?
During the reconnaissance survey, the surveyor prepares a neat hand sketch of the area, called a reference sketch or index map, or key plan. This sketch shows the skeleton of the survey work. This key plan also indicates the positions of main survey stations, sub-stations, tie stations, baselines, arrangements of frameworks of triangles, and the approximate location of different objects. This sketch is a very important document for the surveyor and for the person who will plot the map.
What is the optical square in surveying?
An optical square is an instrument used by surveyors for setting out right angles (i.e., 90°). There are two glasses in the instruments (i) Horizon glass and (ii) Index glass.
What is horizon glass?
A horizon glass is fixed at the bottom of the metal box of the optical square. The lower half of the horizon glass is un-silver and the upper half is silvered. The horizontal glass is placed at an angle of 120° with the horizontal sight.
What is index glass?
An index glass is fixed at the bottom of the metal box of the optical square. This index glass is completely silvered. This is placed at an angle of 105° with index sight.
What is the angle between the horizon glass and the index glass?
The angle between the horizon glass and the index glass is maintained at 45°.
What is the working principle of an optical square?
An optical square works on the principle of reflecting surfaces, the angle between the first incident ray and the last reflected ray is twice the angle between the mirrors. In this case, the angle between the mirrors is fixed at 45°, so the angle between the horizontal sight and the index sight will be 90°.
What is the least count of a metric chain?
The least count of a metric chain is 20cm or 0.2 m.
How many types of obstacles of chaining are there?
A chain line may be obstructed in the following three ways -(i) Chaining free but the vision obstructed (e.g., jungle area), (ii) Chaining obstructed but vision free (e.g., pond), (iii) Chaining and vision both obstructed (e.g, building ).
What is the use of a ranging rod?
These are used for range, in other words, the process of making a line straight. Ranging rods are generally circular in section, 25mm in diameter, and 2m in length.
What is the use of cross-staff?
Cross-staff is an instrument used by surveyors for setting out right angles. There are three types of cross-staff -(i) open cross-staff (ii)French cross-staff (iii) adjustable cross-staff.
How many types of compass are used in surveying?
Two types- (i) prismatic compass (ii) surveyors compass
What is the principle of the Compass survey?
The principle of compass survey is traversing. In this method, magnetic bearings of a series of connected lines are measured with a compass and the distances between them are measured with a chai or tape. A compass survey does not require the formulation of a network of triangles.
In which area does compass surveying is not recommended?
Compass surveying is not suitable for the areas where the local attraction is suspected due to the presence of magnetic substances and electric cables.
What is the closing error?
The actual distance by which a traverse fails to close in case of a closed traverse.
What is the size of a field book?
This is the notebook in which field measurements are noted down during surveying. The size of a field book is 12 cm X 20 cm with two centrelines 12.5 mm to 15mm apart and it opens lengthwise.
What is the space between two entries in a field book?
Minimum 10 mm.
What is the prismatic compass?
This is an instrument used in surveying for measuring magnetic bearings. 85 mm to 110 mm in diameter, least count (i,e., minimum graduation) 30 minutes. 0° is marked at the south, 90° at the west, 180° at the north, and 270° at the east. Graduations are read through the prism.
What is a traverse?
A series of connected survey lines whose length and direction are known as traverse.
What is the bearing of a line?
It is the horizontal angle made by a line with any other reference direction.
What is a true meridian?
It is the vertical plane passing through the true north, true south, and the place.
What is a magnetic meridian?
It is the vertical plane passing through the magnetic north, magnetic south, and place.
What is a true bearing?
The angle or bearing made by a line with reference to the true meridian is known as a true bearing.
What is a Magnetic bearing?
The angle or bearing made by a line with reference to the magnetic meridian is known as a magnetic bearing.
What is Magnetic declination?
The horizontal angle between the true meridian and magnetic meridian is called declination.
What is the whole circle system of bearing?
In this system, the magnetic bearing of a line is measured clockwise from the north towards the line. A whole circle bearing may have a value between o° and 360°. A prismatic compass is used to measure the whole circle bearing of a line.
What is the fundamental difference between a prismatic compass and a surveyor’s compass?
A prismatic compass measures a magnetic bearing in a whole circle bearing system whereas in surveyors compass measures in the reduced bearing system.
What is the least count of the prismatic compass?
The Least Count of the Prismatic Compass generally depends on the graduation of its main scale. If 1° is divided into two divisions then the least count is 30′ ( i.e. thirty minutes). In the same way, 1° is divided into three divisions then the least count is 20′ (i.e. twenty minutes).
What is isogonic and agonic line ?
The isogonic line is the line passing through the equal declination.
The agonic line is the line passing through points of zero declination.
What is the chain angle?
The angle between any two adjacent sides is fixed by chain and tape only by taking a tie line is called a chain angle.
What is the local attraction?
The disturbing magnetic influence due to the presence of a magnetic substance on the magnetic needle is known as a local attraction.
How would you recognize the presence of local attraction in an area?
If the fore bearing and back bearing do not differ by exactly 180°, the local attraction is present in the area.
What is the check (angular ) of a closed traverse?
The sum of the interior angles should be equal to (2n-4)x 90°, where n is the number of the sides of the traverse.
What is the principle of the plane tabling?
The principle of the plane table survey is parallelism.
What method would you adopt for locating inaccessible points?
The method of intersection should be adopted in this case.
What is a datum surface?
An arbitrarily assumed level surface from which the elevation of various objects is measured.
What are the different types of benchmarks?
Four types of benchmarks are there – GTS BM, permanent BM, temporary BM, and arbitrary BM.
What are benchmarks?
These are the reference points whose RL (reduced level) is fixed with respect to the datum surface.
What does the term GTS mean?
Great Trigonometrical Survey.
What are the differences between a horizontal surface and a level surface?
The level surface is the surface parallel to the mean spheroidal surface of the earth. but the surface which is tangential to the level surface at any point is the horizontal surface.
The water surface of a still lake is considered the level surface. But the horizontal surface is perpendicular to the direction of gravity (indicated by the plumb line).
What is the difference between the line of collimation and the axis of the telescope?
The imaginary line joining the points of intersection of the crosshairs to the optical center of the object-glass is known as the line of collimation. But the imaginary line joining the optical center of the object-glass to that of the eyepiece is known as the axis of the telescope.
What is the relation between the axis of the telescope and the line of collimation?
These two lines should coincide.
What is the change point?
The change point indicates the shifting of the instrument (Auto level or Dumpy level). At this point, two staff readings are taken – a foresight is taken from one setting (previous) and a backsight is taken from the next setting.
What is the method of leveling by foot screws?
At first, the telescope is placed parallel to any pair of the foot screws, and the bubble is brought to the canter by turning the foot screws equally either inwards or outwards. Then the telescope is then turned through 90° and the bubble is brought to the canter by turning the third foot screw. This process is repeated until the bubble always is in the canter in any position of the telescope.
Suppose an auto-level is given to you whose line of collimation is not in adjustments: what is the method that you would follow in order to work with this instrument?
To work with this instrument, we have to maintain that the level should always be placed exactly midway between backsight and foresight. This way the collimation error will be adjusted.
How will you continue levelling across a river?
For leveling across a river reciprocal leveling method should be adopted.
What are the arithmetical checks for the rise-fall method and height of the instrument method?
In the rise-fall method:
∑BB-∑FB = ∑Rise -∑ Fall = last RL – first RL
In the height of the instrument method :
∑BB-∑FB = last RL- first RL
What is check leveling?
Check leveling is done in longitudinal leveling at the end of the day’s work to check the accuracy of the work. In this case, the finishing point is connected to the starting point by fly leveling.
What would you mean by positive and negative reduced level?
The elevation of a point above the datum surface is known as positive RL.
The elevation of a point below the datum surface is known as negative RL.
What are the differences between permanent and temporary adjustment of levels?
The temporary adjustment is done at each setup of the instrument before taking any staff reading. The permanent adjustment is done in order to rectify any disturbance between the fundamental survey lines.
What is fly leveling?
Fly leveling is a type of leveling in which only BS(backsight) and FS (foresight) readings are taken and no intermediate sights are taken is known as fly leveling.
Fly leveling is done for connecting the benchmark to the starting point of any project. In this type of leveling, no horizontal distance is required to be measured.
What is contour line?
It is a line joining point of equal elevation.
What is a planimeter?
An instrument used for measuring an area of a field from the map.
What is an Azimuth?
The true bearing of a line is known as azimuth.
What is the trunnion axis?
The horizontal axis of a line is known as the trunnion axis.
What is transiting?
Transiting is rotating the telescope in a vertical plane through 180°.
What is swinging?
Transiting is rotating the telescope in a horizontal plane.
What is the degree of a curve?
The angle subtended at the center of the circle by the unit chord of 30m is known as the degree of the curve.
What is the radius of a 1° curve?
The radius of a 1° curve is 1718.9 m.
What is the relation between the degree of curve and radius of curvature?
Degree of the curve (D)= 1719/Radius of the curvature(R).
Who is the first surveyor-general of India?
Major James Rennell was the first Surveyor-General of India (1767-1777).
Who is the father of surveying?
Major James Rennell is the father of surveying.
Where is the headquarters of Survey of India located?
The headquarters of Survey of India is located at Dehradun.
Who made India’s map first?
Major James Rennell constructed the first India map.
Where first India’s map was published?
India’s first map was published at A Bengal Atlas in the year 1781 which was Digitized on 13 November 2012.
Who is the current surveyor-general of India?
Shri Sunil Kumar is the current surveyor-general of India
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