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ELEMENTARY SURVEYING FIELD
MANUAL
FIELD WORK NO. 5 DIFFERENTIAL LEVELING WITH AND
WITHOUT TURNING POINTS
CE120-0F / A1
SUBMITTED BY:
NAME: STUDENT NO.:
GROUP NO. 4
DATE OF FIELD WORK: AUGUST 7, 2014
DATE OF SUBMITTION: AUGUST 14, 2014
CHIEF OF PARTY:
SUBMITTED TO:
PROFESSOR: ENGR. CERVANTES
GRADE
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FIELD WORK NO. 5 DIFFERENTIAL LEVELING WITH AND WITHOUT TURNING POINTS
FINAL DATE SHEET
FIELD WORK 5 DIFFERENTIAL LEVELING WITH AND WITHOUT TURNING POINTS
DATE: AUGUST 7, 2014 GROUP NO.: 4 TIME: 8:30AM – 12:00PM LOCATION: INTRAMUROS GROUND WEATHER: SUNNY PROFESSOR: ENGR. CERVANTES
A. DIFFERENTIAL LEVELING: WITHOUT TURNPING POINT (SINGLE SET-UP)
STATION BS FS DIFFERENCE IN ELEVATION
MEAN OR MOST PROBABLE DIFFERENCE
IN ELEVATION
A 155 cm 133 cm 22 cm 14 cm
B 146 cm 140 cm 6 cm
B. COMPUTATIONS:
Difference in ElevationA = |BS – FS|
Difference in ElevationA = |155 cm – 133 cm|
Difference in ElevationA = 22 cm
Difference in ElevationB = |BS – FS|
Difference in ElevationB = |146 cm – 140 cm|
Difference in ElevationB = 6 cm
Mean Difference in Elevation = Difference in Elevation A+ Difference in Elevation B
2
Mean Difference in Elevation = 22 cm +6 cm
2
Mean Difference in Elevation = 14 cm
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FIELD WORK NO. 5 DIFFERENTIAL LEVELING WITH AND WITHOUT TURNING POINTS
C. DIFFERENTIAL LEVELING: WITH TURNING POINT (SINGLE RODED)
STATION BS HI FS ELEVATION REMARKS
BM-1 1.465 m 101.465 m 100 m
TP-1 1.462 m 101.462 m 1.465 m 100 m
TP-2 1.465 m 101.492 m 1.435 m 100.027 m
BM-2 1.44 m 101.467 m 1.465 m 100.027 m
TP-3 1.49 m 101.537 m 1.42 m 100.047 m
TP-4 1.445 m 101.512 m 1.47 m 100.067 m
BM-1 1.442 m 100.07 m
D. COMPUTATIONS:
H.I. = ELAEVATION + B.S.
H.I. = 100 m + 1.465 m
H.I. = 101.465 m
ELEVATION = H.I. – F.S.
ELEVATION = 101.465 m – 1.465 m
ELEVATION = 100 m
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FIELD WORK NO. 5 DIFFERENTIAL LEVELING WITH AND WITHOUT TURNING POINTS
E. SKECTH
FIGURE 1 FIGURE 2
Figure 2 portraits the instrument man, together with the recorder, reading the height of the
back sight from the leveling rod held by the rod man.
FIGURE 3
Taking the foresight (FS) reading of the leveling rod.
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FIELD WORK NO. 5 DIFFERENTIAL LEVELING WITH AND WITHOUT TURNING POINTS
DISCUSSION
Leveling is the measurement of geodetic height using an optical leveling instrument
and a level staff or rod having a numbered scale. Leveling is a branch of surveying, the
object of which is to find the elevation of a given point with respect to the given or assumed
datum and establish a point at a given elevation with respect to the given or assumed
datum.
Leveling is done for following purposes:
1. To prepare a contour map for fixing sites for reservoir dams, barrages etc… and to
fix the alignment of roads, railways, irrigation canals, and so on.
2. To determine the altitudes of different important points on a hill or to know the
reduced levels of different points on or below the surface of the earth.
3. To prepare a longitudinal section and cross-section of a project (road, railways,
irrigation cannels, etc) in order to determine the volume of earth work.
4. To prepare a layout map for water supply, sanitary or drainage schemes.
Leveling is classified into three types: geometric leveling, trigonometric leveling, and
precise leveling. In geometric leveling the difference of height between two points is
determined by differences of readings to the leveling rod placed on those points. The
readings are made with a leveling instrument.
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FIELD WORK NO. 5 DIFFERENTIAL LEVELING WITH AND WITHOUT TURNING POINTS
While in trigonometric leveling the difference in elevation between two points is
determined by measuring distance (slope or horizontal) and vertical angle.
And lastly, precise leveling is a particularly accurate method of geometric leveling
which uses highly accurate levels and with a more rigorous observing procedure than
general engineering leveling. In precise leveling we aim to achieve high orders of accuracy
such as 1 mm per 1 km traverse.
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FIELD WORK NO. 5 DIFFERENTIAL LEVELING WITH AND WITHOUT TURNING POINTS
CONCLUSION
On this field work, we tried to determine the difference in elevation between two
points, both of which are accessible from a single point of observation using a dumpy level
and find the elevation of a point from a benchmark of unknown elevation. Based on the
data gathered, the elevation of the ground we observed is not really leveled. The ground
elevation fluctuates from a range of 0 to 6 cm.
According from the lecture being discussed, a well-leveled ground should have the
same elevation with respect to the sea level. The common sources of error on this field
work are the inaccurate reading of measurements, human errors and instrumental errors.
Human errors include not holding the leveling rod in a vertical position. While instrumental
errors include if the instrument/s used for getting the data in the field work, which is precise
level for this field work, is/are defective or if the instrument’s bubble is not centered.
It is recommended to have patience in doing the field work because this field work
has so much part and a lot to be done. Also check first if the measuring tape is completely
perpendicular to the ground before recording the measurement to lessen the error that
might be acquired. Using a plumb bob is also recommended to see if the measuring tape is
perpendicular to the ground. Team work is also required for this experiment because
everyone has their assigned task to do to finish the field work on time. Follow the
instructions on the manual carefully to avoid errors.
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FIELD WORK NO. 5 DIFFERENTIAL LEVELING WITH AND WITHOUT TURNING POINTS