Sunday 5 August 2018

Booking of Detail.




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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