EQUIPMENTS FOR CHAIN
SURVEY
SURVEY
The following equipments
are required for conducting chain survey:
are required for conducting chain survey:
- Metric
chain (20 m)
=
1 no. - Arrows
=
10 nos. - Metallic
tape (15
m)
= 1 no. - Ranging
rods
= 3 nos. - Offset
rod
=
1 no - Clinometer
=
1 no - Plumb
bob with
thread
= 1 no - Cross
staff or optical square
=
1 no - Prismatic
compass with stand
= 1 no. - Wooden
pegs
=
10 nos. - Mallet
=
1 no - Field
book
=
10 nos. - Good
pencil
=
1 no - Pen
knife
=
1 no. - Eraser
(rubber)
= 1 no.
3.7 THE FIELD BOOK
The notebook in which
field measurements are noted is known as the ‘field book’. The size of the
field book is 20 cm x 12 cm and it opens lengthwise. Field books may be of two
types:
field measurements are noted is known as the ‘field book’. The size of the
field book is 20 cm x 12 cm and it opens lengthwise. Field books may be of two
types:
- Single
–line , and - Double-line.
1. Single-line
field book In this type of
field book, a single red line is drawn through the middle of each page. This
line represents the chain line, and the chainages are written on it. The
offsets are recorded, with sketches, to the left or right of the chain line.
The recording of the field book is started from the last page and continued
towards the first page. The main stations are marked by ‘’ and subsidiary
stations or tie stations are by ‘’
field book In this type of
field book, a single red line is drawn through the middle of each page. This
line represents the chain line, and the chainages are written on it. The
offsets are recorded, with sketches, to the left or right of the chain line.
The recording of the field book is started from the last page and continued
towards the first page. The main stations are marked by ‘’ and subsidiary
stations or tie stations are by ‘’
2. Double-line
field book In this type of
field book, two red lines, 1.5 cm apart, are drawn through the middle of each
page. This column represents the chain line, and the chainages are written in
it. The offsets are recorded, with sketches, to the left or right of this
column. The recording is begun from the last page and continued towards the
first. The main stations are marked by ‘’ and subsidiary or tie stations by ‘’
This type of field book is commonly used.
field book In this type of
field book, two red lines, 1.5 cm apart, are drawn through the middle of each
page. This column represents the chain line, and the chainages are written in
it. The offsets are recorded, with sketches, to the left or right of this
column. The recording is begun from the last page and continued towards the
first. The main stations are marked by ‘’ and subsidiary or tie stations by ‘’
This type of field book is commonly used.
A. Problems on Entering
Records in Field Book
Records in Field Book
Problem 1 While measuring a chain line AB, the
following offsets are taken. How would you enter the field book ?
following offsets are taken. How would you enter the field book ?
(a) A telegraph post is
10 m perpendicularly from chainage 2.5 m to the right of the chain line.
10 m perpendicularly from chainage 2.5 m to the right of the chain line.
(b) A road crosses
obliquely from left to right at chainage 10 m and 14 m. Perpendicular offsets
are 2m and 3m to the side of the road from chainage 5m and 20 m respectively.
obliquely from left to right at chainage 10 m and 14 m. Perpendicular offsets
are 2m and 3m to the side of the road from chainage 5m and 20 m respectively.
(c) A tube-well is 5m
perpendicularly from chainage 30 m to the left of the chain line.
perpendicularly from chainage 30 m to the left of the chain line.
(d) Total chainage of AB
is 45 m.
is 45 m.
Problem 2 The base line AC of a chain survey is
measured and the following records are noted. Make the necessary entries in a
field book.
measured and the following records are noted. Make the necessary entries in a
field book.
(a) The corners of a
building are 9 and 9,5m from chainage 7.5 and 18 m to the left of the chain
line. The building is 7m wide.
building are 9 and 9,5m from chainage 7.5 and 18 m to the left of the chain
line. The building is 7m wide.
(b) A 4 m wide road runs
about parallel to the right of the chain line. Offsets are 2,2.1,2.2, and 2.15m
at chainages 0,20,40, and 55.5m respectively.
about parallel to the right of the chain line. Offsets are 2,2.1,2.2, and 2.15m
at chainages 0,20,40, and 55.5m respectively.
(c) A check line is
taken from the sub-station at chainage 25 m to the left.
taken from the sub-station at chainage 25 m to the left.
(d) The total chainage
of the base line is 55.5m.
of the base line is 55.5m.
(e) The fore bearing and
back bearing of the base line are 30030’ and 21003C’
respectively.
back bearing of the base line are 30030’ and 21003C’
respectively.
Problem 3 Enter the field book according to the
following field notes:
following field notes:
(a) Chainage of line AB
is 95.5m
is 95.5m
(b) The offsets to the
pond at the left of chain line are as follows:
pond at the left of chain line are as follows:
Chainage –
10,15,20,25,30 m
10,15,20,25,30 m
Offset – 16,12,10,14,20
m
m
(c)
The offsets to the river at the right of the chain line are :
The offsets to the river at the right of the chain line are :
Chainage – 5,25,40,80 m
Offset -13,17,19,19.5m
B. Precautions to be
Taken While Entering the Field book
Taken While Entering the Field book
1. All measurements
should be noted as soon as they are taken.
should be noted as soon as they are taken.
2. Each chain line
should be recorded on a separate page. Normally it should start from the bottom
of one page and end on the top of another. No line should be started from any
intermediate position.
should be recorded on a separate page. Normally it should start from the bottom
of one page and end on the top of another. No line should be started from any
intermediate position.
3. Over –writing should
be avoided.
be avoided.
4. Figures and
hand-writing should be neat and legible.
hand-writing should be neat and legible.
5. Index-sketch,
object-sketch and notes should be clear.
object-sketch and notes should be clear.
6. Reference sketches
should be given in the field book, so that the station can be located when
required.
should be given in the field book, so that the station can be located when
required.
7. The field book should
be entered in pencil and not in ink.
be entered in pencil and not in ink.
8. If an entry is
incorrect or a page damaged, cancel the page and start the entry from a new
one.
incorrect or a page damaged, cancel the page and start the entry from a new
one.
9. Erasing a sketch,
measurement or note should be avoided.
measurement or note should be avoided.
10. The surveyor should
face the direction of chaining so that the left-hand and right-hand objects can
be recorded without any confusion.
face the direction of chaining so that the left-hand and right-hand objects can
be recorded without any confusion.
11. The field-book
should be carefully preserved.
should be carefully preserved.
12. The field-book
should contain the following:
(i) name,
should contain the following:
(i) name,
(ii) location, and
(iii) date, of survey,
(iv) name of party
members, and
members, and
(v) page index or chain
line.
line.
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