Ge 105 lecture 3 (LEVELING ADJUSTMENT) by: Broddett B. Abatayo
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ENGR. BRODDETT B. ABATAYO, GE, REA Part - time Lecturer – GE division, CEIT, CSU, Ampayon , Butuan City Research Assistant – Phil - LiDAR 2 Project, CSU, Ampayon , Butuan City Proprietor – BPA ABATAYO Land Surveying Services 1 with CASIO fx-991 es plus Calculator Technique Lecture 3 Caraga State University College of Engineering and Information Technology Ampayon , Butuan City 8600 LEVELING ADJUSTMENT GE 105 – Theory of Errors and Adjustments
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Transcript of Ge 105 lecture 3 (LEVELING ADJUSTMENT) by: Broddett B. Abatayo
ENGR. BRODDETT B. ABATAYO, GE, REA
Part-time Lecturer – GE division, CEIT, CSU, Ampayon, Butuan CityResearch Assistant – Phil-LiDAR 2 Project, CSU, Ampayon, Butuan City
Proprietor – BPA ABATAYO Land Surveying Services1
with CASIO fx-991 es plus Calculator Technique
Lecture 3
Caraga State University
College of Engineering and Information Technology
Ampayon, Butuan City 8600
LEVELING
ADJUSTMENT
GE 105 – Theory of Errors and Adjustments
PEG METHOD OF
ADJUSTMENT
In a two peg test using dumpy level, the following observations were taken:
1. What is the true difference in elevation between A and B?
2. Determine the error in the line of sight for the net distance AB ?
3. Determine the correct reading at A that will give level line of sight with the instrument still at point P.
A
B
M
PEG METHOD OF ADJUSTMENT
line of sight
level line
Rod reading Instrument M set
up near at A
Instrument P set
up near at B
on point A
on point B
1.623 m
2.875 m
In a two peg test using dumpy level, the following observations were taken:
Rod reading Instrument M set
up near at A
Instrument P set
up near at B
on point A
on point B
1. What is the true difference in elevation between A and B?
2. Determine the error in the line of sight for the net distance AB ?
3. Determine the correct reading at A that will give level line of sight with the instrument still at point P.
A
PEG METHOD OF ADJUSTMENT
0.362 m
P
1.623 m
2.875 m
B
1.622 m
Ans. 1.) 1.256 m
2.) 0.004 m
3.) 0.366 m
The line of sight of a wye level was tested by setting up exactly midway between two points A and B.
Rod reading Instrument M midway
bet. A and B
Instrument P
near at B
on point A 1.520m 1.683m
on point B 1.395m 1.490m
1. What is the true difference in elevation between A and B?
2. What is the error in the line of sight?
3. Determine the reading at A that will make the line of sight horizontal with the instrument still at
point P?
A
B
M
PEG METHOD OF ADJUSTMENT
The line of sight of a wye level was tested by setting up exactly midway between two points A and B.
A
B
P
PEG METHOD OF ADJUSTMENT
1. What is the true difference in elevation between A and B?
2. What is the error in the line of sight?
3. Determine the reading at A that will make the line of sight horizontal with the instrument still at
point P?
Ans. 1.) 0.125m
2.) - 0.068m
3.) 1.615m
Rod reading Instrument M midway
bet. A and B
Instrument P
near at B
on point A 1.520m 1.683m
on point B 1.395m 1.490m
P
1
To make peg adjustment, the following notes were taken.
Wye level @ 1 Wye level @ 2
Rod reading @ P 0.75m 1.906m
Rod reading @ Q 2.766m 3.789m
Point 1 is on the line PQ and midway between P and Q. Point 2 is on the same line as P and Q but not between them. Point 2 is 25m from P and 230m from Q. With the wye level at point 2, what is the rod reading at P for a level sight?
PEG METHOD OF ADJUSTMENT
Q
To make peg adjustment, the following notes were taken.
Point 1 is on the line PQ and midway between P and Q. Point 2 is on the same line as P and Q but not between them. Point 2 is 25m from P and 230m from Q. With the wye level at point 2, what is the rod reading at P for a level sight?
Ans. 1.921
2
PEG METHOD OF ADJUSTMENT
P
Q
Wye level @ 1 Wye level @ 2
Rod reading @ P 0.75m 1.906m
Rod reading @ Q 2.766m 3.789m
ADJUSTMENT OF
LEVEL CIRCUIT
Adjustment of LEVEL CIRCUITS
The known elevation of BM1 is 728.730m. A 30,500m long level circuit is run, closing back on BM1 with an elevation, as determined from the notes, of 728.486m. The observed elevations of other bench marks which were established during the run, and their distances from the initial bench mark are given as follows:
Sta Distance from BM1 km
Observed elevation m
BM6
BM1
BM2
BM3
BM5
BM4
BM1 0.000 728.730
BM2 5.245 783.213
BM3 11.271 891.764
BM4 17.718 843.195
BM6 25.247 702.956
BM1 30.500 728.486
BM5 21.964 739.708
728.486m
702.956m
739.708m
843.195m
891.764m
783.213m
728.730m
Determine the ff:
1.) The error of closure.2.) Correction to be applied to each observed
elevation.3.) Adjusted elevations of the bench marks along the
level route.
Adjustment of LEVEL CIRCUITS
BM6
BM1
BM2
BM3
BM5
BM4
728.486m
702.956m
739.708m
843.195m
891.764m
783.213m
728.730m
Determine the ff:
1.) The error of closure.2.) Correction to be applied to each observed
elevation.3.) Adjusted elevations of the bench marks along the
level route.
ADJUSTMENT OF
LEVEL NET
1. From the following observation shown, compute the adjusted elevation of A, B and C when the elevation of D and E are 100m and 130m, respectively. (30pts.)
A
C
BD = 100 m
E = 130 m
QUIZ 3 ½ cross wise
-15.193
