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INTRODUCTION

Levelling is a method to measure the elevation difference between two (2) or more

points. In this practical, focus is shifted to one of levelling techniques namely , fly level

observation or also known as the rise and fall method . The observation will be initiated

from a known reduced level (RL) value of a benchmark (BM) and end at another

known RL value of BM. In between the BMs, a number of change points (CPs) will be

set up to observe the fore sight reading and the back sight reading of each stationed

staves and the values are booked. Upon completion of the observation, the RL values

will be calculated and booked. After the RL values are known, three (3) arithmetical

checks will be calculated to ensure the precision of the works. Consequently, the

adjustment value can be computed where this value will be distributed accordingly to

each station. Finally, the adjusted RL values are booked and the misclosure will be

calculated to be compared with the adjusted values to determine whether the levelling

works is accepted or unsatisfactory.

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OBJECTIVE

Objective in this report for :

1. To carry out fly level observation (Rise and Fall method) from bench mark (BM)

to temporary bench mark (TBM).

2. To compute the transferred RL from BM/SBM to TBM.

3. To adjust and check the levelling data.

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INSTRUMENT

1. Tripod

2. Staff

3. Level

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4. Staff bubble

5. Picket

6. Hammer

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PROCEDURE

GENERAL PROCEDURE

1. Adjust the height of the tripod to balanced the level properly.

2. Set the level. Adjust the screw below of the tripod to tighten the level on the

tripod.

3. Adjust the bubble until the bubble stay on the center.

4. Ask your groupmate to hold the staff at the BM, and take the reading.

SPECIFIC PROEDURE

FIGURE 1.1

1. The level is set up at a convenient position, I1. The staff is held on the BM and a

reading is taken. This will be a back sight (BS), because it is the first staff reading

after the levelling instrument has been set up. The length of foresight and back

2. The staff is moved to point A and take reading. This will be a foresight (FS). And

point A will be a change point (CP).

3. Next, the levelling instrument is moved to position I2 and the staff is left at point A

and point B on the change point (CP). The staff is turned so that it faces the level

and a reading is taken. This will be a back sight for point A and fore sight for

point B.

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4. Next, the levelling instrument is moved to position I3 and the staff is left at point B

and point C on the change point (CP). The staff is turned so that it faces the level

and a reading is taken. This will be a back sight for point B and fore sight for

point C.

5. The same step is repeated for the position I4. The level instrument is set up and

the reading for both staff at point C and D are taken.

6. While the staff remains at D, the instrument level is moved to another position, I5.

A reading taken from new position to the staff at D and E. D is a BS and E is a

FS.

7. The level moved to position I6 and staff at point E be a BS. The staff at TBM1 be

a FS.

8. The staff is moved to TBM and F in turn and reading taken while the level at I7

Point F will be the FS and TBM will be an BS.

9. When the level is at position I8, the staff have been moved at point F and G. the

point F will be the BS and the G will be the FS.

10. Staff moved to position I9 and the point will be at G and H. The point G will be

the BS and H will be the FS.

11. Move the level at position I10 and move the staff at point I and point H then take

both readings. The BS is point I and FS is point H.

12. The same step for position I11,move the staff at point I and point J and take the

readings.

13. Finally, the level is moved to I12, a BS is point J and FS is the BM. The final staff

position is at a point of known RL. This is most important as all levelling

fieldwork must start and finish at points of known reduced level, otherwise it is

not possible to detect misclosures in the levelling.

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RESULT & ANALYSIS

The reading are shown booked by the rise and fall method in table 1.1. These are

normally recorded in a level book containing all the relevant column. Each line of the

level book corresponds to a staff position and this is confirmed by the entries in the

Remarks column. The calculation proceeds in the following manner, in which the

reduced level of a points is related to that of a previous point.

BS IS FS RISE FALL REDUCED

LEVEL

CORRECTION ADJUSTMENT

REDUCED

LEVEL

DISTANCE REMARKS

1.090 12.875 0 12.875 TBM =

12.875

1.127 1.117 0.027 12.848 -0.010 12.838 A

1.118 1.120 0.007 12.855 -0.019 12.836 B

1.129 1.126 0.008 12.847 -0.029 12.818 C

1.118 1.120 0.009 12.856 -0.038 12.818 D

0.290 1.120 0.002 12.854 -0.048 12.806 E

2.162 1.144 0.854 12.000 -0.057 11.943 TBM 2=

11.943

1.180 1.255 0.907 12.907 -0.067 12.840 F

1.230 1.305 0.125 12.782 -0.076 12.706 G

1.412 1.250 0.030 12.812 -0.086 12.726 H

1.261 1.335 0.077 12.889 -0.095 12.794 I

1.155 1.081 0.180 13.069 -0.105 12.964 J

1.235 0.080 12.989 -0.114 12.875 TBM =

12.875

TABLE 1.1

1. From the first BM to A a BS of 1.090 m has been recorded at the BM and FS of

1.117 m at A. The resulting height difference is given by (1.090 m – 1.117 m) = -

0.027 m. The positive sign indicates the fall and is entered at point A.

2. The procedure is repeated and the height difference from A to B is given by

(1.127 m – 1.120 m) = + 0.007 m. This is entered as rise at point B.

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3. When calculating the rises or falls in the FS or IS column must be subtracted

from the line immediately above, either in the same column or one column to the

left. The FS is subtracted from the IS or BS in the line above and the BS on the

same line as the FS is the used to continue the calculation with the next IS or FS

in the line below.

4. When the table is complete, a check on the arithmetic involved is possible and

must always be applied. This check is

∑ (BS ) -∑ ( FS ) = ∑ ( RISES ) -∑ ( FALLS ) = RL – ADJUSTMENT RL

5. In table 1.1, the difference between the adjusted RL of the first BM and adjusted

RL of the final BM is 0.00. The result show that the levelling is accurate and

pricise. It is mean that we do not have to make an adjustment.

6. The allowable misclosure for any levelling sequence is allowable misclosure

= ±5√ n mm where n is the number of instrument positions. If the actual value is

greater than the allowable value, the levelling should be repeated. However, if

the actual value is less than the allowable value, the misclosure should be

distributed equally between the instrument positions.

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BS IS FS RISE FALL REDUCED

LEVEL

CORRECTION ADJUSTMENT

REDUCED

LEVEL

DISTANCE REMARKS

1.251 11.891 0 11.891 0 TBM=11.891

0.451 0.800 12.691 -0.007 12.684 5 1

0.453 0.002 12.689 -0.007 12.682 10 2

0.448 0.005 12.694 -0.007 12.687 15 3

0.495 0.047 12.647 -0.007 12.640 20 4

0.425 0.070 12.717 -0.007 12.710 25 5

0.452 0.027 12.690 -0.007 12.683 30 6

0.460 0.008 12.682 -0.007 12.675 35 7

0.475 0.015 12.667 -0.007 12.660 40 8

0.483 0.008 12.659 -0.007 12.652 45 9

0.480 0.003 12.662 -0.007 12.655 50 10

1.442 0.472 0.008 12.670 -0.007 12.653 55 11 CP)

2.140 0.698 11.972 -0.014 11.958 62.071 13

2.159 0.019 11.953 -0.014 11.939 67.071 14

2.109 0.050 12.003 -0.014 11.989 72.071 15

2.105 0.004 12.007 -0.014 11.993 77.071 16

2.158 0.053 11.954 -0.014 11.940 82.071 17

2.179 0.021 11.933 -0.014 11.919 87.071 18

2.210 0.031 11.902 -0.014 11.888 92.071 19

2.215 0.005 11.897 -0.014 11.883 97.071 20

1.240 2.190 0.025 11.922 -0.014 11.908 102.071 21 (CP)

1.365 0.125 11.797 -0.02 11.959 109.142 23

1.354 0.011 11.808 -0.02 11.788 114.142 24

1.369 0.015 11.793 -0.02 11.773 119.142 25

1.405 0.036 11.757 -0.02 11.737 124.142 26

1.388 0.017 11.774 -0.02 11.754 129.142 27

1.400 0.012 11.762 -0.02 11.743 134.142 28

1.389 0.011 11.773 -0.02 11.753 139.142 29

1.408 0.019 11.754 -0.02 11.734 144.142 30

1.370 0.038 11.792 -0.02 11.772 149.142 31

1.425 0.055 11.737 -0.02 11.717 154.142 32

1.356 0.069 11.806 -0.02 11.786 159.142 33

1.251 0.105 11.911 -0.02 11.891 164.142 TBM=11.891

TABLE 1.2

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COMPUTATION

1. Arimethic checking

FORMULA : ∑ (BS ) -∑ ( FS ) = ∑ ( RISES ) -∑ ( FALLS ) = LAST RL – LAST ARL

3.936 – 3.853 = 1.216 – 1.196 = 11.911 – 11.891 = 0.020

2. Misclosure

FORMULA : (± 5 √𝑛) = 𝑛 = 𝑡𝑜𝑡𝑎𝑙 𝑝𝑜𝑠𝑖𝑡𝑖𝑜𝑛 𝑜𝑓 𝑙𝑒𝑣𝑒𝑙

±5√3 = 8.66 𝑚𝑚

FORMULA : (± 0.012 √𝐽)𝑚 = 𝐽 = 𝑡𝑜𝑡𝑎𝑙 𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒 𝑖𝑛 𝐾𝑀

= (±0.012√0.164)

= ±0.00486

3. Correction

0.02

3=0.07

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CONCLUSION

We manage to carry out fly level observation from Bench Mark (BM) to Temporary

Bench Mark (TBM). All the readings data were booked by the rise and fall method.

Arithmetical check was applied in fly level method for verify the accuracy of calculation.

ƩBS – ƩFS = Ʃ RISES – Ʃ FALLS = LAST RL – LAST ARL is the arithmetical check to

verified the accuracy of calculation. The leveling was done from a known BM to

unknown TBM and reversed to the known BM again. Then we compute the transferred

level from BM to TBM and compute the level back to the BM to checked our data is

correct.

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REFERENCES

1. SURVEYING FOR ENGINEERS : J.UREN AND W.F.PRICE : THIRD EDITION :

ISBN 0-333-57705-1 .

2. LECTURE NOTE, PROF SR. DR. HJ. ABD MANAN BIN HJ.SAMAD,

ENGINEERING SURVEYING 1

3. MODUL POLITEKNIK KEMENTERIAN PENDIDIKAN MALAYSIA, C1005 UKUR

KEJURUTERAAN 1 : MOHAMAD KELANA BINTI JUWIT: MOHD FAHMI BIN

ABD RAZAK