Booking of Detail.
Field Book
The notebook in which field measurements are noted is known as the
‘field book’. Generally the size of the field book is 20 cm x 12 cm and it open
lengthwise. Field books may be of two types:
1. Single-line, and
2. 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. The line
represents the chain line, and the chainages are written on it. The offsets are
recorded, with the sketches, to the left or right of the chain line. The
recording of the field book is started from the last page. The main stations
are by ‘Օ’ (Fig. 32).
3. Double-line
field book In this type of field book
two red line, 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 the sketches, to the left or right of this column. The
recording is begin from the last page and continued towards the first. The main
stations are marked by ‘∆’ and the subsidiary or tie stations by ‘Օ’ (Fig. 33). This type of field book is
commonly used.
Example on Entering Record in Field Book.
Example-I While measuring a chain line
AB, the following offsets are taken.
(a)
A telegraph post
is 10 metre perpendicularly from the chainage 2.5 metre to the right of the
chain line.
(b)
A road crosses
obliquely from left to right at cgainage 10 metre and 13 metre. Perpendicular
offsets are 2 metre and 3 metre to the side of the road from chainage 5 metre
20 metre respectively.
(c)
A tube-well is 7
metre perpendicularly from chainage 30 metre to the left of the chain line.
(d)
Total chainage
of AB is 45 metre.
Example-II
Base line
AC of a chain survey is measured and the following records are noted.
(a)
The corners of
the building are 8 metre and 10 metre from chainage 8 and 19 metre to the left
of the chain line. The building is 7.5 metre wide.
(b)
A 3 metre wide
road runs about parallel to the right of the chain line offsets are taken 1.8,
1.9, 2.0 and 2.05 metre at chainage 0, 20,40 and 60 respectively.
(c)
The fore bearing
and back bearing of the base line are 45⁰-30’ and 230⁰-30’ respectively.
(d)
Total chainage of
base line is 60 metre.
Example-III
While
measuring a chain line AB, the following offsets are taken.
(a)
Chainage of line
AB is 100.00 metre.
(b)
The offsets to
the ditch at the left of chain line are follows: Chainage – 12, 15, 20, 28 and 33 metre.
Offset- 13, 9, 7, 10 and 18
metre
(c)
The offsets to
the road at the right of chain line are
Chainage – 7, 13, 25, 45 and 78 metre.
Offset- 9, 14, 17, 20 and
21.5 metre.
Precautions to be taken while Entering the Field Book.
1. All measurements 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 top
of another. No line should be started from any intermediate position.
. 3. Over-writing should be avoided.
4. Figure and hand-writing should be neat
and legible.
5. Index-sketch, object-sketch and note
should be clear.
6. Reference sketches 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 not in ink.
8. If an entry is 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.
10. The surveyor
should face the direction of chaining so that the left-hand and right-hand
objects can be recorded without any confusion.
11. The field book
carefully preserved.
112. The field book
should contain the following- (i) Name, (ii) Location, (iii) Date of survey,
(iv) name of party members and (v) Page index of chain line.
(Next post on “Plotting Detail & Scale of plotting”)
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