site surveying report 1

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BACHELOR OF QUANTITY SURVEYING (HONOURS) QSB60103103946-M - SITE SURVEYING Fieldwork Report 1 TITLE: LEVELING Name Student ID Yeo Dor Een 0316224 Welson Lum Wei Jiunn 0319514 Yap Jia En 0319550 Yong Sing Yew 0318766 1

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Page 1: Site surveying report 1

BACHELOR OF QUANTITY SURVEYING (HONOURS)

QSB60103103946-M - SITE SURVEYING

Fieldwork Report 1

TITLE: LEVELING

Name Student IDYeo Dor Een 0316224

Welson Lum Wei Jiunn 0319514

Yap Jia En 0319550Yong Sing Yew 0318766

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Table of Content

Content PagesCover Page 1

Table of Content 2Introduction to Leveling 3-5

Introduction of Apparatus 6-11Data and Results 12-14

Discussion 16

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INTRODUCTION TO LEVELINGLeveling may be part of determine the relative heights or elevation of points are object on the

earth’s surface. It deal with measurements in a vertical plane. It is also a level surface that

everywhere at right angles to the direction of gravity of the earth.

OBJECTIVES

The objectives of this field work 1 (Leveling) is to:

a) To give definitions as a basic for the proper understanding of leveling

b) To understand the methods used in leveling

c) To understand the collimation method and rise and fall method

There are few definitions of terms used in leveling which are:

DATUM

A datum may be a surface or a line to which observed heights are related. It is any arbitrarily

assumed level surface or line from which vertical distances are measured in India the datum

adopted for G.T.S. bench marks is the mean sea level at Karachi now in Pakistan. There are two

types of datum which are:

a) The ordnance datum (O.D) is the datum to which all heights shown on Ordnance Sydney

(O.S) maps are referred. The datum line is the mean sea level at Liverpool datum

b) Assumed datum is used where it is inconvenient or impossible to relate the work in hand

to the ordnance datum.

BENCH-MARK (B.M)

Bench-mark is a fixed point of know height above O.D from which the height above O.D of any

other point may be pointed. Bench-mark also used as our starting point and ending point during

our field work.

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REDUCED LEVEL

A reduced level is the height of a point or object stated with reference to the selected datum for

the work in hand. The reduced level can be increase or decrease at every points depends on the

datum. There are some formula to get the amount of reduce level which are:

a) The height of instrument - Back sight= Reduced level (Collimation method)

b) The previous height of instrument – (I.S) or (B.s)= Reduced level(Collimation Method)

For the rise and fall method is use the previous B.S to minus the I.S or F.S to get the amount

which will be negative or positive amount and add them with the reduced level of the previous

B.S.

LINE OF COLLIMATION

It is the line joining the intersection of cross hairs of the optical center of the object glass. The

line extending from an instrument along which distance objects are seen, when viewed with the

telescope. It also called the line of sight.

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BACKSIGHT

Back-sight is the first sight reading taken after the instrument has been set up. The sight taken to

a point whose height is known, has been assumed, or can be calculated. Its abbreviated is called

B.S and is taken at the start of the work at and a change point.

FORESGHT

Foresight also called the last staff reading denoting the shifting of the instrument. It is a termed

as minus sight. It is abbreviated to F.S and is taken a change point and at the end of operations.

INTERMEDIATE SIGHT

Intermediate sight is the sight or reading that take between the F.S and B.S. It is abbreviated to

I.S.

CHANGE POINT

It is appoint denoting the shifting of the level. It is after the reading of B.S and F.S where the

instrument is ready to move to a new position. It is abbreviated to C.P. A bench-mark may also

be taken as a changer point and it also called a turning point (T.P).

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APPARATUS USEDTelescope/Digital Level

1. Object Lens

2. Focusing Screw

3. Focusing Lens

4. Diaphragm

5. Eyepiece

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Tripod Stand

It have 3 legs which can be extend to the height required. It function is to carry the Digital Level

and it has a special screw is done purposely to lock the Optical Plummet which attached to the

Digital Level.

Optical Plummet

A device which use to make sure the Digital Level is on the center position over a point.

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Way to set-up the Optical Plummet so that the Digital Level are at the center position

Rotate A and B at the same time and C at the different time to adjust the bubble move into the

center which mean the Digital Level is already in the center position. Do not rotate the three

rotate buttons at the same time.

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Pond Bubble

-When pond bubble is centered this mean the instrument’s standing axis is approximately

vertical.

-The compensators in the instrument take over and adjust the optical of Line of Collimation so

that it is horizontal.

-When the instrument is rotated the compensator ensure that a horizontal plane of collimation is

swept out.

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E-type leveling ruler

This type of ruler can allow us have a better vision on the reading compare to normal type ruler.

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COMMON ERROR SOURCES

There are always some common error sources due to the failure of the measurement. The

common error sources are:

a) Level rod not vertical

b) Levelling rod not fully extended or incorrect length

c) Level instrument not level

d) Instrument out of adjustment

e) Environment – wind and heat.

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Data/ Result of Leveling

Height of Collimation Method

Backsight Intersight Foresight Height of Collimation

Reduced Level

1.519 101.519 100.0001.429 3.785 99.163 97.7341.369 1.330 99.202 97.8331.439 1.555 99.086 97.6471.631 1.495 99.222 97.5911.378 1.345 99.255 97.8771.303 1.384 99.174 97.8711.423 1.553 99.044 97.6211.490 1.391 99.143 97.6533.675 1.480 101.338 97.6631.479 1.317 101.500 100.021

1.468 100.03218.135 18.103 100.032

18.103 100.0000.032 0.032

Rise and Fall MethodBacksight Intersight Foresight Rise Fall Reduced

Level1.519 100.0001.429 3.785 2.266 97.7341.369 1.330 0.099 97.8331.439 1.555 0.186 97.6471.631 1.495 0.056 97.5911.378 1.345 0.286 97.8771.303 1.384 0.006 97.8711.423 1.553 0.250 97.6211.490 1.391 0.032 97.6533.675 1.480 0.010 97.6631.479 1.317 2.358 100.021

1.468 0.011 100.03218.135 18.103 2.796 2.764 100.032

18.103 2.764 100.000

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0.032 0.032 0.032

Adjusted Field Data

Height of Collimation Method

Backsight Intersight

Foresight Height of Collimation

Reduced Level

Adjustment Final Reduce Level

1.519 101.519 100.000 100.0001.429 3.785 99.163 97.734 -0.003 97.7311.369 1.330 99.202 97.833 -0.006 97.8271.439 1.555 99.086 97.647 -0.009 97.6381.631 1.495 99.222 97.591 -0.012 97.5791.378 1.345 99.255 97.877 -0.015 97.8621.303 1.384 99.174 97.871 -0.018 97.8531.423 1.553 99.044 97.621 -0.021 97.6001.490 1.391 99.143 97.653 -0.024 97.6293.675 1.480 101.338 97.663 -0.027 97.6361.479 1.317 101.500 100.021 -0.030 99.991

1.468 100.032 -0.032 100.00018.135 18.103 100.032

18.103 100.0000.032 0.032 Arith.

Checked

Rise and Fall MethodBacksigh

tIntersight Foresigh

tRise Fall Reduced

LevelAdjustment Final

Reduce Level

1.519 100.000 100.0001.429 3.785 2.266 97.734 -0.003 97.7311.369 1.330 0.099 97.833 -0.006 97.8271.439 1.555 0.186 97.647 -0.009 97.6381.631 1.495 0.056 97.591 -0.012 97.5791.378 1.345 0.286 97.877 -0.015 97.8621.303 1.384 0.006 97.871 -0.018 97.8531.423 1.553 0.250 97.621 -0.021 97.6001.490 1.391 0.032 97.653 -0.024 97.629

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3.675 1.480 0.010 97.663 -0.027 97.6361.479 1.317 2.358 100.021 -0.030 99.991

1.468 0.011 100.032 -0.032 100.00018.135 18.103 2.796 2.764 100.032

18.103 2.764 100.0000.032 0.032 0.032 Arith.

CheckedAcceptable Error of closure = ±12 √k

K = the number of set-ups

±12 √11 = ±39.799mm

Hence, the leveling is acceptable.

Correction per set-up

Error of misclosure ÷ Number of set up

= (100.0000-100.032) ÷ 11

= -0.003 m

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Discussion For the first fieldwork, we were required to set up the leveling instrument on a

suitable spot. After finished set up, the height of instrument will remain the same

for each observation made until the instrument is moved to a new position. Two

persons carried their own level rods (vertical rods) stood at two different points and

mark the places with correction fluid. Then, the level rods’ readings were

measured and recorded. We were asked to measure 11 points (included bench-

mark) with 10 set ups in this fieldwork. After that, calculate the readings we

recorded in two methods which are height of collimation method and rise and fall

method and calculate the reduced level of each station. To ensure the total readings

are same or within the allowable error of closure, we use the formula of constant ×

√(distance).

constant × √(distance)

= ± 12 √k

= ± 12 √11

= ± 39.799mm

Therefore, the acceptable range for error of closure is ± 39.799mm. If the answer

is over ± 39.799mm, we have to do the fieldwork again until we get it. For our

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group, we get the answer for the allowable error of closure, -0.032mm, thus it is

acceptable. After that, we need to do adjustment table for height of collimation

method and rise and fall method with this formula:

Correction per set-up

Error of misclosure ÷ Number of set up

= (100.0000-100.032) ÷ 11

= -0.003 m

Lastly, calculate the final reduced level with the addition of reduced level and

adjustment.

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