surveying - module i - introduction to surveying
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OPTC Edavanna Page 1
MODULE I: INTRODUCTION TO SURVEYING
1. Define surveying?
Art/Science of determining the relative positions of points on, above or below earths
surface by means of direct or indirect measurement of distances, elevations or
2. What are the primary objects of surveying?
a) Preparation of plans / maps
b) To find horizontal distances b/w points
c) To find elevation (height) b/w points
d) To find relative and absolute directions
3. What are the primary divisions of surveying?
a) Plane survey
Curvature of earth is not considered
For small areas
b) Geodetic survey
Curvature of earth is considered
For large areas
4. Write down the cardinal principles of surveying?
a) Working from whole to part
Area to be surveyed is divided into large triangle and further divided into
small triangles (Triangulation)
A system of control points is identified and located with high precision
To prevent accumulation of errors
To control and localize minor errors
b) Locating a point with reference to two fixed points
5. List classification of surveying based on instrument used?
a) Chain surveying
b) Compass surveying
c) Theodolite surveying
d) Plane table surveying
e) Tachometric surveying
Orphanage Polytechnic College, Edavanna REVISION PACKAGE
Surveying - I ( Revision 2015)
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6. Name instruments required for chain survey?
a) Chain or tape
c) Ranging rods
d) Cross staff
e) Offset rods
g) Plumb bob
7. What is reconnaissance? What is its importance in chain surveying?
Before starting the actual survey, surveyor walks around the area to prepare a
reference sketch of the ground to fix best positions of survey lines and stations.
To check the possibility of a building / constructing road through that area
To choose best route and mark on maps
To prepare estimate and draft report
This gives the surveyor an overall idea of the land and the important features.
8. What is mean by ranging? What is direct and indirect ranging? or Write the
basic methods of ranging out survey lines?
The process of establishing intermediate points on a straight line between the end
stations is called ranging. Intermediate ranging rods are placed to maintain correct
direction. There are two methods of ranging on slopping grounds.
a) Direct ranging
b) Indirect ranging
When the starting, ending points and intermediate stations are intervisible along a
straight line. It can be done by eye, line ranger or theodolite.
Line Ranger: The line Ranger is a small reflecting instrument used for fixing
intermediate points on the chain lines. Without going to either end, we can fix the
(i) To range a point P, two ranging rods are fixed at ends A and B
(ii) Surveyor hold the line ranger near AB
(iii) The reflected rays forms imag, but may not be in same vertical line.
(iv) Surveyor moves the line ranger sideways till both images are in same
vertical line as in figure.
(v) Point P is transferred to ground with help of plumb bob
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If the end stations are not intervisible due to hill/other land features.
Also known as reciprocal ranging
9. What is mean by reciprocal ranging? Write the condition under which the
reciprocal ranging is resorted to. Explain the procedure for indirect ranging?
It is the method of fixing intermediate station points b/w two terminal points, when
they are not intervisible. This method is adopted under following situations or
A raising ground b/w the two end points
A hill (Steeply raising ground) b/w the end points
A deep valley b/w the end points
1. The ranging rods are drawn vertically at A and B
2. The person carrying ranging rods C and D should be sent to the positions
that they are to be visible from A and B.
3. The initial positions of C and D are marked on the ground as C1 and D1
4. The surveyor at A will now direct the man at C1 to put his rod at C2 in line with
A and D1
5. The surveyor at B will next direct the man at D1 to put his rod at D2 in line with
B and D2
6. This process is repeated several times till the points C and D are found out in
the line AB
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10. Briefly explain the direct and indirect method of measuring distances, if the
ground is slopping?
There are two methods of chaining on sloping grounds,
Direct method (Method of stepping or stepping method):
The horizontal distance between A and B is measured in small horizontal steps
Total horizontal distance = l1 + l2 + l3 + l4
The follower holds the zero end of the tape at A while the leader selects any
suitable length of tape and moves forward.
In case of irregular slopes, this is the only suitable method
Indirect method: Three types
a) By using clinometer
b) By applying hypotenusal allowance
Correction is applied in the field at every chain length and at every point
where the slope changes
BC Hypotenusal allowance
c) By knowing the difference of level between the points
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11. What is well conditional triangle and ill conditional triangles?
well conditional triangle ill conditional triangle
Error is minimized due to equal
Error gets accumulated in one
angle or one length only
All angles are nearly equal to 600 Angles are 120
12. Explain reference sketch, Index sketch?
Index sketch Reference sketch
It is a rough sketch of the
entire area to be surveyed
It is a rough sketch showing
location/reference of a
All lines, stations,
topographical features are
minimum two distances are
shown w.r.t. permanent
object like building
Useful for proper selection of
Used for locating a station
13. Explain the principle on which chain survey is based? Mention the different
methods generally adopted to find the areas from previously plotted plan?
Basic principle used in chain survey is triangulation. The plotted framework is
divided into number of connected triangles.
14. Explain the terms: Main line, Base line, Check line, Tie line?
Main Line: Lines joining main stations Base line : Biggest line that divides the total area almost into two parts
Check line: Lines drawn to check accuracy of survey
Tie line : Lines drawn to collect more details of object 15. Describe different types of chain used for linear measurements?
Following are the various types of chain in common use
1) Metric chains
2) Gunter` s chain or surveyors chain
3) Engineers chain
4) Revenue chain
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Metric chains are made in lengths 20 m and 30 m.
Tallies are fixed at every 5 m length
Brass rings are provided at every one meter length except where tallies are
20 m chain has 100 links and 30 m chain has 150 links.
Length of one link is 20 cm.
Gunters or Surveyors Chain
It is 66 feet long
It is divided into 100 links
Each link is 0.66 feet long
It is 100 feet long
It is divided into 100 links
Each link is 1 feet long
It is 33 feet long
It is divided into 16 links
Each link is 2.06 feet long
16. Mention the three different operations in chain surveying?
(i) Ranging: The process of locating intermediate points on a straight line between two end points in a straight line
(ii) Chaining: The process of measuring the distance with a chain or tape. (iii) Offsetting: The process of measuring the lateral distance of the object from the
survey line to the left or right according to their positions.
17. Explain the process of setting plane table over a station?
(i) Fixing: Fixing the table on the tripod
(ii) Setting : (a) Levelling the table (b) Centering (c) Orientation
(iii) Sighting the points
18. How levelling is done in plane table survey?
For small work, levelling is done by estimation. For accurate works, spirit level is used
19. What is meant by centering?
The process of making the point correctly on paper by placing the table exactly over
the ground station point is called centering.
20. What is orientation?What are the different methods of orientation of plane table?
Orientation is the process of putting the plane table into some fixed direction so that
the line representing a certain direction on the plan is parallel to the direction on the
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The methods of orientation are
(i) Orientation by means of trough compass