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Booking
and Reduction
The information that needs to be booked is similar to that required
for the area levelling procedure.
The main thing to note for the booking procedure is that the BS
reading and FS reading to the same CP (staff position) are booked
on the same line. See table 1 at the right.
- The
reduction method for the series levelling is referred to a the
Rise and Fall method and is carried out as follows:
- All
BS, FS and Intermediate sights readings are booked in the appropriate
columns of the levelling field book.
- The
BS reading to the BM is booked in the back site column and the
name of the BM is booked in the remarks column.
-
The staff is moved to the next CP and a fore sight reading is
booked on the next line and the remarks column noted as a CP.
-
If any intermediate sights are taken then they are each booked
on a separate line as for the Area Levelling technique. See table
2 at the right.
- The
rise and fall (dH) between each successive point is then found
by subtracting the last level observation from the one previous
See table 3 at the right..
-
The RL for each successive point can then be determined by adding
the Rise or Fall to the preceding line RL.
RLA = RLBM + ( Fall)
RLA = 145.150 + (-2.297) = 142.853
RLB = 142.853 + (-0.607) = 142.246
-
Once the RL's for each point have been determined, the maths is
checked by:
SBS - SFS = SR - SF = RLLast - RLFirst
Any misclose between the given RL of the last point and the reduced
RL of that point is distributed through the survey linearly - see
attached example sheet- Misclose = RLGiven - RLLevelled.
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