Introduction
Of Chain Surveying
China survey is a
traditional method of surveying which does not have much accuracy. This survey
is done for a less important project or to get preliminary information about a important
project. In this survey, China is used to measure the length of survey lines. There
is different type of chain. its selection according to the purpose of the
survey.. All this information is entered in the field book.
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| Chain Surveying |
Instruments
Used In Chain Surveying
Distance
Measuring Instruments
·
Chain
·
Steel band
·
Tap
Instruments
For Ranging
·
Ranging Rod
·
Line Ranger
Angles
Measuring Instruments
·
Abney Level
·
Clino Meter
Marking
Instrument
·
Arrow
·
Peg
Perpendicular
Erecting Instrument
·
Cross Staff
·
Optical Square
Graphical
Instrument
·
Plani Meter
·
Panta Graph
ININTRODUCTION OF SURVEYING (TOPIC # 1)
Method
For Chain Surveying
i.
Reconnaissance
ii.
Preparation Of Index Plan
iii.
Selection Of Station Points
iv.
Selection Of Base Line
v.
Chaining
vi.
Taking Offset
vii.
Drawing Work
Reconnaissance
A preliminary survey of
the entire area is carried out before starting the China survey And the index
of the whole area is planned. These places include roads, canals, streams,
canals, railway lines, power poles, telephone lines, cemeteries, settlements,
and forests. The area to be surveyed in China is first inspected .In this
inspection, the whole area is surveyed. An index plan is also called a key plan.
Preparation
Of Index Plan
After a preliminary
inspection of the area, a rough sketch of the entire area is prepared. The
sketch which shows the prominent areas of the area such as the boundaries of
the area, railway line, roads, drains, population and cemeteries etc. is called
the Index Plan.
Selection
Of Station Points
After moving around the
area and preparing the index plan, the selection of station points is carried
out. Station points are selected in such
a way that the next and previous stations are visible from each station And they can also be measured. The station
points in the China survey are selected so that the whole area is divided into
different parts and then all the lines are measured with the help of chain and
tape. Care is taken while selecting the station points. The stations are
visible to each other and the distance between them can be measured with the
help of China. There should be no barrier between any two connected stations.
Selection
Of Base Line
After choosing the
station point, the route of the base line and other lines is decided. This is
an important step during which an effort is made to ensure that no area is far
from the survey line so that the details of all the important points can be
obtained and the lines can be passed at a minimum. The baseline is passed
through the middle of the area so that it does not face any obstruction as the
accuracy depends on the same line. The whole area is divided into triangles to
pass the other lines. The choice of check line and tie line is also implemented
to check the survey work.
At this stage the set
take is measured and the data of the key points located around the lines are
obtained.
Chaining
At this stage the baseline is measured and
the details of the key points around it are obtained then similarly other lines
are chained. The distance from the beginning of a point on the chain line is
called changing. Full details of the survey are recorded in the field book.
This description includes reference sketches of all designated stations and
index plan of the entire area and names of all chain lines. For them, the
direction of a single line is recorded with respect to the north direction. Different
station points are also displayed in this diagram. At the same time the
measurement of the important location on both sides of the lines is noted in
the field book in case of changing and offset.
Method For Chain Surveying
Taking
Offset
Their distances from
China are measured to note the different locations around the China Line. The
distance from China to a place is called offset. If this offset forms the angle
of inclination along the chain line, it is called vertical offset. If its angle
is any other than 90 then it is called oblique offset. If the distance of a
point is far from China and the length is not measured there, but the rays are
applied from two places in China, then it is called long offset. The length of
the offset is determined on both sides of the chain line for taking offset. Its
length depends on the importance and nature of the project. After measuring the
chain line, it is measured by laying the chain on it. At this stage the details
of the various bodies present on both sides of the chain line are noted. For
this, the offset is taken to the relevant object from China. Offsets can be
vertical or oblique. One vertical offset number is sufficient while diagonal
offsets are taken for at least two And it is noted on the field book. The
length of the offset and the distance of the chain line at its starting point
are also noted. The maximum length of the offset depends on the importance of
the project for which it is being surveyed. It is usually 30 meters for road
and 100 meters for railway line. If there is an obstruction in the measurement
between the object and the chain line, rays are applied to the object from both
sides of the chain line The radios of these two points along the distance and
the angle formed along the race chain line are noted and all these details are
recorded in the field book.
Drawing
Work
The drawing is then
prepared according to these details. For this the first chain lines are
displayed on the drawing sheet according to the appropriate scale. If there is
a slight decrease in it, it is corrected and then other details are fixed on
these lines and their respective marks are displayed according to the scale.
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| Method For Chain Surveying |
After completing the
survey fieldwork, a drawing of the entire area is prepared. In which all the details
obtained are displayed. The work done is examined before the drawing is
prepared and every effort is made to avoid revealing any details. To prepare
the drawing, first the scale is selected according to the size of the area and
the size of the drawing sheet. Then it is prepared accordingly and all the
details are displayed in it. All these details are displayed with the help of
set marks. To prepare the drawing the first baseline is displayed in the
appropriate direction, according to the selected scale. The other lines are
then displayed on the drawing set, forming triangles. If an error is found
after display, it is removed. Then the data entered in the field is scaled to
the right and left of each line.
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