2. Surveying
• Surveying is the art of determining the relative
positions of different objects on the surface of
the earth by measuring the horizontal
distances between them and by preparing a
map to any suitable scale
3. Object of surveying
• To prepare a map to show the relative
positions of the objects on the earth surface
• Natural features – towns, villages, roads,
railways, rivers etc.
4. Uses of surveying
• To prepare a topographical map – hills, valleys,
rivers, villages etc..
• To prepare a cadastral map showing the
boundaries of fields, houses and other
properties
• To prepare engg map – roads, railways etc..
• To prepare contour map – capacity of
reservoir
5. Uses of surveying
• To prepare geological map showing areas
including underground resources
• To prepare an archeological map including
places where ancient relics
6. General principle of surveying
• To work from whole to part
• To locate a new station by atleast two
measurements (linear or angular) from fixed
reference points
9. Plane surveying
• Curvature of earth is not taken into consideration
– considered plane
• Plane surveying – small area < 250 km2
• line joining any two points is considered a straight
• Triangle formed by any three points is plane
• Lower degree of accuracy
• Conducted by irrigation department, railway
department
10. Geodetic surveying
• Curvature of earth is taken into account
• Extended over larger areas > 250 km2
• Line joining two points – curved
• Triangle formed by any three points –
spherical
• Angles of triangle – spherical angles
• Higher degree of accuracy
• Conducted by Survey of India
23. Instruments used in Chain survey
• Instruments used for measuring distances
– Chain
– Tape
• Instruments used for marking survey station
– Ranging rod
– Offset rod
– Pegs
24. Instruments used in Chain survey
• Instruments used for setting right angles
– Cross staff
– Optical square
• Other instruments
– Arrow
– Plumb bob
25. Chain
• The chain is composed of 100 or 150 pieces of links,
made up of 4 mm diameter galvanized mild steel wire.
• The ends of each link bent into a loop and connected
together by means of three oval rings which offered
flexibility to the chain and make less liable to become
kinked.
• The length of a link is the distance between the
centers of the two consecutive middle rings.
• The end links include the handles.
26. Chain
• Metallic tags or indicators of distinctive
pattern are fixed at various distinctive points
of the chain to felicitate quick reading of
fraction of a chain in surveying
measurements.
28. Metric chain
• Length - 20 and 30 meters .
• To enable the reading of fractions of a chain with
out much difficulty, tallies are fixed at every two-
meter length and small brass rings are provided
at every metre length, except where tallies are
attached.
• Connecting links between two large links are oval
in shape, the central one being a circular ring.
• The length of each link is 0.2 m (20cm) in 20m
chain is provided with 100 links and 30 m chain
divided into 150 links
30. Gunter's Chain
• English Astronomer Mr. Gunter
• length -66 feet - divided into 100 equal parts
• very convenient to measure distances in miles
and furlongs and for measuring land when the
unit of area is an acre
31. Revenue chain
• commonly used for measuring fields in
cadastral survey
• 33 ft long and divided into 16 links
32. Engineers chain
• 100 ft long and is divided into 100 links, each
one foot in length.
• used on all engineering surveys
• distances measured with engineer's chain are
recorded in feet and decimals
33. Tapes
• Tapes are made of various materials and are
therefore divided into five types.
• Cloth or linen
• Metallic
• Steel
• Synthetic material
34. Ranging rods
• either wooden poles or steel rods painted black
and white or red and white alternatively –
visibility
• Lower end is pointed or provided with iron shoe
• two sizes namely, one of 2 m and other of 3 m
and are divided into equal parts each 0.2 m long
• circular or orthogonal in cross-section having 3
cm diameter
• used for ranging lines and also for marking the
points between which the linear measurements
are to be taken
36. Arrows
• Made of tempered steel wire of diameter 4
mm.
• One end of the arrow is bent into a ring of
diameter 50 mm and other end is pointed.
• Arrows are used for counting the number of
chains while measuring a chain line
38. Cross staff
• Whenever it is intended to set a right angle on
a chain line - cross staff
• 3 types of cross staff
– Open type
– French
– Adjustable type
• Open type is most commonly used
40. Chain surveying
• Principle of chain surveying – triangulation
• Area to be surveyed is divided into a number
of small
• Sides of triangles are measured directly on the
field by chain or tape
• No angular measurements are made
41. Chain surveying is recommended when:
• The ground surface is more or less level
• A small area is to be surveyed
• A small-scale map is to be prepared
• The formation of well-conditioned triangles is
easy
42. Chain surveying is unsuitable when:
• The area is crowded with many details
• Area consists of too many undulations
• The area is very large
• Formation of well-conditioned triangles
become difficult due to obstacles
43. Chain and cross staff surveying -
procedure
• In order to calculate the area of any piece of
land which is irregular in shape it is necessary
to divide the area into number of right angled
triangles and trapezoidal in shape.
• Corners along the boundary of the field
should be first identified and named as
A,B,C,D,E,F and G.
45. Chain and cross staff surveying -
procedure
• Any two stations located in opposite sides should
be selected in such a way that distance between
them is the longest of other stations and almost
equal number of corners (stations) are located on
both sides.
• Chaining should be started along the base line
and offset distance of the corners on both sides
are to be measured simultaneously.
• All the details should be entered in the field
observation book.
