Example

Ex13-3 Complete the differential-level notes and determine the error of closure of the level circuit and adjust the elevations of B.M.2 and B.M.3 assuming that the error is constant per set up.

Level book note for Level Net

 

Staff Reading

Height of Instrument (m)

 

R.L. (m)

 

Points

B.S (m)

F.S.(m)

B.M.1
2.125
 
 
 
T.P.1
1.830
2.945
 
 
T.P.2
2.100 
3.225
 
 
T.P.3
1.650
3.605
 
 
B.M.2
2.365
2.805
   
T.P.4
2.885
2.530
   
T.P.5
3.065
2.350
   
B.M.3
3.855
1.100
   
T.P.6
3.270
1.660
   
T.P.7
3.865
2.110
   
B.M.1
 
3.455
 
 

Solution :

 

Staff Reading

Height of Instrument (m)

 

R.L. (m)

 

Points

B.S (m)

F.S.(m)

B.M.1
2.125
 
102.125 
100.000
T.P.1
1.830
2.945
101.010
99.18 
T.P.2
2.100 
3.225
99.885 
97.785 
T.P.3
1.650
3.605
97.93
96.280
B.M.2
2.365
2.805
97.49
95.125
T.P.4
2.885
2.530
97.845
94.960
T.P.5
3.065
2.350
98.56
95.495
B.M.3
3.855
1.100
101.315
97.46
T.P.6
3.270
1.660
102.925
99.655
T.P.7
3.865
2.110
104.680
100.815
B.M.1
 
3.455
 
101.225

 

Error of closure = 101.225 - 100 = + 1.225 m

There are ten (10) set up for the instrument. Thus for each set up, there is an error of 0.1225 m.

Therefore correction for each set up = - 0.1225 m

Adjusted elevation of B.M.2 = 95.125 - 4 x .1225 = 94.635 m

Adjusted elevation of B.M. 3 = 97.46 - 7 x .1225 = 96.603 m

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