FIELD WORK NO. 5 DIFFERENTIAL LEVELING WITH AND WITHOUT TURNING POINTS.pdf

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 POINTS

DIFFERENTIAL LEVELING WITH AND WITHOUT TURNING

DATE: AUGUST 7, 2014 TIME: 8:30AM – 12:00PM WEATHER: SUNNY

GROUP NO.: 4 LOCATION: INTRAMUROS GROUND PROFESSOR: ENGR. CERVANTES

A. DIFFERENTIAL LEVELING: WITHOUT TURNPING POINT (SINGLE SET-UP) STATION

BS

FS

DIFFERENCE IN ELEVATION

A B

155 cm 146 cm

133 cm 140 cm

22 cm 6 cm

MEAN OR MOST PROBABLE DIFFERENCE IN ELEVATION 14 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 = Mean Difference in Elevation =

Difference in Elevation A+ Difference in Elevation B 2 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 BM-1 TP-1 TP-2 BM-2 TP-3 TP-4 BM-1

BS 1.465 m 1.462 m 1.465 m 1.44 m 1.49 m 1.445 m

HI 101.465 m 101.462 m 101.492 m 101.467 m 101.537 m 101.512 m

FS 1.465 m 1.435 m 1.465 m 1.42 m 1.47 m 1.442 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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ELEVATION 100 m 100 m 100.027 m 100.027 m 100.047 m 100.067 m 100.07 m

REMARKS

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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. [4]

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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

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