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SCHOOL OF ARCHITECTURE, BUILDING AND DESIGN
BACHELOR OF QUANTITY SURVEYING (HONS)
SITE SURVEYING (QSB 60103)
SEMESTER 2
FIELDWORK 1 : LEVELLING
NAME STUDENT ID
TANG LAM YU 0324966
TEE WAN NEE 0325074
TEO CHIANG LOONG 0323762
WONG SHER SHENG 0329950
YAP CHOE HOONG 0323161
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CONTENT
NO CONTENT PAGE
COVER PAGE 1
TABLE OF CONTENT 2
1.1 INTRODUCTION TO LEVELLING 3-8
1.1 Levelling
1.2 Tools Used in Levelling
1.3 Uses Of Levelling
1.4 Definition of Terms Used in Levelling
1.5 Booking Methods
1.6 Differential Levelling
2.0 OUTLINE APPARATUS 9 - 13
2.1 Automatic Level
2.2 Adjustable Leg Tripod
2.3 Levelling Rod/ Levelling Staff
2.4 Optical Plummet
2.5 Bull’s Eyes Level ( Spirit Bubble )
3.0 OBJECTIVE 14
4.0 LEVELLING FIELDWORK MAP 15
5.0 FIELDWORK 16 – 18
5.1 Field Data
5.2 Adjusted Data
6.0 GROUP PHOTO 19
7.0 CONCLUSION AND DISCUSSION 20
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----
Surveying / Land Surveying
A technique/profession which determines the terrestrial or 3-D position of points and
distances and angles between them.
WHAT IS LEVELLING?
1.1 Levelling
Levelling is the measurement of geodetic height using an optical levelling instrument and a
level staff or rod having a numbered scale or it can be said also as a process of finding the
elevation at a specified location relative to another known elevation. It is the determination
of the elevation of a point or difference between points referenced to some datum. The
general term applied to any various processes by which elevations of points or differences
in elevations are determined.
Levelling is the general term applied to any of the various processes by which elevation are
determined. It is a vital operation in producing necessary data for mapping, engineering
design, and construction. Levelling results are used to:
Design highways, railroads, canals, sewers, water supply systems and other
facilities having grade line that best conform to existing topography.
Lay out construction project according to planned elevations
Calculate volumes of Earthwork and other materials
Investigate drainage characteristics of an area
Develop maps showing general ground configurations
Study of Earth subsidence and crustal motion
Common levelling instrument includes the spirit level, the dumpy level, digital level and also
the laser level
1.2 Tool used in levelling
Automatic Level
A device which gives a truly horizontal line.
Levelling staff
A suitably graduated staff for reading vertical heights.
1.0 INTRODUCTION TO LEVELLING
Levelling
Staff
Automatic
Level
FIGURE 1.1.2A levelling staff and automatic level
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1.3 Uses of Levelling.
1. To establish bench mark as vertical control points - serves as references for other
levelling.
2. To enable surveyor to calculate whether 2 points are inter-visible from each other on
ground surface.
3. To enable surveyors’ measurements to be reduced to the horizontal at sea level.
4. To provide information about the geometrical shape and structure of Earth.
1.4 Definition of terms used in surveying
TERM DEFINITION
LEVEL SURFACE A surface that is everywhere perpendicular to the direction of gravity
of Earth. It is also any surface parallel to the mean spheroidal surface
of the Earth. A level surface may be also regarded as a curved
surface, every point on which is equidistant from the center of the
Earth.
DATUM The level of a point or the surface with respect to which levels of
others points or plants are calculated. Which then is categorized into
2 :-
Ordnance Datum (O.D.) - a datum to which all heights shown
on Ordnance Survey (O.S.) maps are referred to. Hence the
datum line is the mean sea level at Liverpool datum.
Assumed Datum- is used where it is inconvenient or
impossible to relate the word in hand to the ordnance datum.
BENCH MARK
(B.M)
A fixed reference point on Earth’s surface whose level above O.D. is
known that are provided by the Department of Survey and Mapping
TEMPORARY
BENCH MARK
(T.B.M)
The benchmark that is established at the end of the day’s work, so
that the next work can be continue from this point. Such point should
be on a stable and (semi)permanent object so that it can be easily
identified.
CHANGE POINT
(C.P)/
TURNING POINT
(T.P)
The point at which fore-sight and back-sight are taken. It is an
arbitrary point which enables levelling to be continued from a new
instrument position.
ORDINARY
LEVELLING
The level surfaces at different elevations can be considered to be
parallel. A level datum is an arbitrary level surface to which
elevations are referred.
LINE OF
COLLIMATION
The true horizontal line of sight which passes through the optical
center of the telescope of the ‘level’ where they are in perfect
alignment.
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There are a few important terms used especially for data recording, namely:-
TERM DEFINITION
REDUCED LEVEL
(R.L)
The level of a point taken as height above datum surface, is known
as R.L. of that point. It is the height or elevation of survey points
stated with reference to a common assumed datum.
BACK-SIGHT
(B.S)
The first sight (reading) taken after setting up the instrument (level).
INTER-MEDIATE
SIGHT
(I.S)
Readings taken between back-sight and fore-sight. Also called the
‘inter-sight’ readings.
FORE-SIGHT
(F.S)
The last sight (reading) taken before moving the instrument or last
set-up. It is also a reading taken at a point whose height is required.
HEIGHT OF
INSTRUMENT
The elevation of the line of sight in the telescope of the level.
SETUP 1
SETUP 2
BM
FIGURE 1.1.5A terms used in levelling
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1.5 Booking methods:-
There are 2 booking methods which are:-
Height of Collimation
Rise & Fall Method (both are for vertical control survey)
Table 1: Rise & Fall Method
Back-
sight
Inter-
mediate
Fore-
sight
Rise Fall
Reduced
level
Distance
(m)
Remarks
T W 0 Given BM (X)
U
T – U =
+A
W + A = X 20 A
U1
U – U1
= -B
X – B = Y 40 B
V
U1 – V
= +C
Y + C = Z 60 C
Σ(BS) Σ(FS) ΣR ΣF
Last RL =
Z
First RL =
W
Difference
should be equal
If A & C is POSITIVE
(+), it will be RISE
If B is NEGATIVE
(-), it will be FALL
Fall (-) /Rise (+)
Procedure of booking the rise and fall method :
Back-sight, Intermediate sight and foresight readings are being entered in the appropriate
columns on different lines. However, back-sights and foresights are being placed on the
same line if there are turning points.
The first reduced level is the height of datum, benchmark or reduced level (R.L)
If an intermediate sight or foresight is SMALLER than the immediatey preceding staff
reading then the difference between the two reading is being placed in the RISE column.
If the intermediate sight or foresight is LARGER than the immediately preceding staff
reading than the difference berween the two readings is placed in the FALL column
A RISE is ADDED to the preceding reduced level (R.L) and a FALL is SUBTRACTED from
the preceding R.L
Rise and Fall Method :- Σ(BS) - Σ(FS) = ΣR - ΣF = Last RL - First RL
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Table 2: Height of Collimation Method (height of instrument)
Procedure of booking the height of collimation method :
Booking is the same as the rise and fall method for back-sight, intermediate sight and fore-
sight.There are no rise and fall method, instead a height of collimation method.
The first back-sight reading (staff on datum, benchmark or RL) is added to the first RL giving
the height of collimation
The next staff reading is entered in the appropriate column but on a new line. The RL for the
station is found by subtracting the staff reading from the height of collimation.
The height of collimation changes only when the level is moved to a new position. The new
height od collimation is found by adding the back-sight to the RL at the change point.
There is no check on the accuracy of the intermediate RL’s and errors could go undetected
1.6 Arithmetic check (for both methods)
- Arithmetic calculations can be checked whether or not there is no assurance that errors in
the field procedure. It proves that is the methods are being correctly recorded in the data.
- If the arithmetic calculations are correct,
Height of Collimation Method
Σ(BS) - Σ(FS) = Last RL - First RL
Rise and Fall Method
Σ(BS) - Σ(FS) = ΣR - ΣF = Last RL - First RL
Back-
sight
Inter-
mediate
Fore-
sight
Height of
collimation
Reduced
level
Distance
(m)
Remarks
Y Y+ Z = X Z 0
Given
BM
A1 X - A1 = Z1 20 A
A2 X - A2 = Z2 40 B
Y3 A3 Y3 + Z3 = X1 X - A3 = Z3 60
C
(turning
point)
A4 X1 - A4 = Z4 80 D
A5 X1 - A5 = Z5 100 E
Σ(BS) Σ(FS) Last RL = Z5
Differenc
e should
be equal
Height of Collimation Method :- Σ(BS) - Σ(FS) = Last RL - First RL
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1.7 Differential Levelling
The establishment of differences in elevation between two or more points with
respect to a datum, with process of repeated levelling at each instrument setup.
This method is used to find the difference in the elevation between points if they are
too far apart or the difference in elevation between them is too much.
*the proceeding steps will be shown in the Field Data measurements. (eg:- error
distribution, accuracy check, mis-closure and adjustment)
FIGURE 1.1.8A Differential Levelling
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2.1 AUTOMATIC LEVEL
An automatic level is an optical instrument used in surveying and building to transfer,
measure, or set horizontal levels. An Auto Level is a Professional Leveling Tool used by
Contractors, Builders, Land Surveying Professionals, or the Engineer who demands
accurate leveling every time. Auto Levels set up fast, are easy to use, and save time and
money on every job.
The automatic level instrument is set up on a tripod stand and depending on the type,
either roughly or accurately set to a leveled condition using footscrews ( levelling screws ).
The operator looks through the eyepiece of the telescope while an assistant holds a tape
measure or graduated staff vertical at the point under the measurement. The instrument
and staff are used to gather and/or transfer elevations (level) during site surveys or building
construction. Measurement generally starts from a benchmark with known height
determined by a previous survey, or an arbitrary point with an assumed height.
An automatic level, self-levelling level, or builder's auto level includes an internal
compensator mechanism (a swinging prism) that, when set close to level, automatically
removes any remaining variation. This reduces the need to set the instrument truly level, as
with a dumpy or tilting level. Self-levelling instruments are the preferred instrument on
building sites, construction, and during surveying due to ease of use and rapid setup time.
Sighting of automatic level
Sight towards the staff using the gun sight. Look through the eyepiece and focus the reticle
by gradually turning the reticule focusing ring anti-clockwise. Turn the focusing knob to
focus on the staff. Turn the fine motion screw to centre the staff in the field of view. Turn the
focusing knob to eliminate parallax between the staff and reticule.
2.0 OUTLINE OF APPARATUS
Figure 2.1A Front view of automatic level Figure 2.1B Side view of automatic level
Figure 2.1D View from automatic level
Figure 2.1C Section of automatic level
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2.2 ADJUSTABLE LEG TRIPOD ( TRIPOD STAND )
A surveyor's tripod is a device used to support any one of a number of surveying
instruments, such as theodolites, total stations, levels or transits.
Modern tripods are constructed of aluminum, though wood is still used for legs. The feet are
either aluminum tipped with a steel point or steel. The mounting screw is often brass or
brass and plastic. The mounting screw is hollow and has two lateral holes to attach
a plumb bob to center the instrument e.g. over a corner or other mark on the ground.
After the instrument is centered within a few cm over the mark, the plumb bob is removed
and a viewer (using a prism) in the instrument is used to exactly center it.
https://4.imimg.com/data4/WH/YB/MY-1658977/aluminium-tripod-for-auto-level-500x500.png
The tripod is placed in the location where it is needed. The surveyor will press down on the
legs' platforms to securely anchor the legs in soil or to force the feet to a low position on
uneven, pock-marked pavement. Leg lengths are adjusted to bring the tripod head to a
convenient height and make it roughly level and being locked by a lever clamp ( left ) or
screw (right).
Once the tripod is positioned and secure, the instrument is placed on the head. The
mounting screw is pushed up under the instrument to engage the instrument's base and
screwed tight when the instrument is in the correct position. The flat surface of the tripod
head is called the foot plate and is used to support the adjustable feet of the instrument.
Positioning the tripod and instrument precisely over an indicated mark on the ground or
benchmark requires intricate techniques.
Figure 2.2A Adjustable Leg Tripod
Figure 2.2B clamp and screw of leg tripod
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2.3 LEVELING ROD / LEVELING STAFF
A level staff, also called levelling rod, is a graduated wooden or aluminium rod, used with
a levelling instrument to determine the difference in height between points or heights of
points above a datum surface. It cannot be used without a leveling instrument.
Levelling rods can be one piece, but many are sectional and can be shortened for storage
and transport or lengthened for use. Aluminum rods may be shortened by telescoping
sections inside each other, while wooden rod sections can be attached to each other with
sliding connections or slip joints, or hinged to fold when not in use.
There are many types of rods, with names that identify the form of the graduations and
other characteristics. Markings can be in imperial or metric units. Some rods are graduated
on one side only while others are marked on both sides. If marked on both sides, the
markings can be identical or can have imperial units on one side and metric on the other.
Figure 2.3A leveling staffs
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Reading the Leveling Staff
The staff starts at zero, on the ground. Every 10 cm is a number, showing (in meters to one
decimal) the height of the bottom of what appears to be a stylized E (even numbers) or 3
(odd numbers), 5 cm high. The stems of the E or 3 and the gaps between them are each
10mm high. These 10mm increments continue up to the next 10 cm mark.
To read the staff, take the number shown below the reticle. Count the number of whole
10mm increments between the whole number and the reticle. Then estimate the number of
mm between the last whole 10mm block and the center of the reticle. The diagram above
shows 4 readings:- 1.950, 2.000, 2.035 and 2.087.
The person holding the staff should endeavor to hold it as straight as possible. The leveler
can easily see if it is tilted to the left or right, and should correct the staff-holder. However, it
cannot easily be seen that the staff is tilted towards or away from the leveler. In order to
combat this possible source of error, the staff should be slowly rocked towards and away
from the leveler. When viewing the staff, the reading will thus vary between a high and low
point. The correct reading is the lowest value.
Digital levels electronically read a bar-coded scale on the staff. These instruments usually
include data recording capability. The automation removes the requirement for the operator
to read a scale and write down the value, and so reduces blunders. It may also compute
and apply refraction and curvature corrections.
Figure 2.3B Reading the leveling staff
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2.4 OPTICAL PLUMMET
In surveying, a device used in place of a plumb bob to centre transits and theodolites over
a given point, preferred for its steadiness in strong winds. The device consists of two
triangular metal plates connected at their corners by levelling thumbscrews, a bubble level,
a locking mechanism and often an optical plummet. The device will be attached to the
tripod and placed over the plummet.
The bubble shown in Figure 2.4B (left) is being adjusted using the foot screw so that the
foot screw can be in the middle of the cross hair as shown in Figure 2.4B (right)
2.5 BULL’S EYES LEVEL ( SPIRIT BUBBLE )
Spirit level is a tool that is being used to indicate how parallel (level) or perpendicular
(plumb) a surface is relative to the earth. A spirit level gets its name from the mineral spirit
solution inside the level.
The vials in a spirit level are yellowish-green colour with additives for UV protection and
maximum performance in temperatures ranging from -20ºF – 130ºF. The best spirit level is
accurate to within plus or minus 0.5 mm/M, or 0.005 inches/inch or 0.029º. The next level of
accuracy displayed is 0.75mm/M or 0.043º.
The vial bodies of a spirit level, also referred as a bubble level can be shaped like a barrel,
like rectangular block or even curved, banana-shaped, to measure slope in fractions per
foot of pitch, and are mostly made from acrylic today versus glass originally.
Sensitivity is an important specification for spirit level as the accuracy depends a lot on the
sensitivity. The sensitivity of level is given as the change of angle or gradient required to
move the bubble by unit distance.
Figure 2.4A Optical Plummet
Figure 2.5 Spirit Bubble
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To learn basic levelling principles, theory and application and to able to calculate
the levelling data.
To enhance student knowledge in the leveling procedure
To enable student experience in setting up and working with the auto level.
To allow student to learn the correct method in doing leveling measurement
To understand how to record back sight (BS), intermediate sight (IS) and fore sight
(FS) with the correct readings.
To determine the difference in height of discrete point
To determine the error of misclosure in order to determine whether the leveling is
acceptable.
To identify the reduced level of each staff station
3.0 OBJECTIVE
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4.0 LEVELING FIELDWORK (TAYLOR’S UNIVERSITY LAKESIDE CAMPUS ZONE F & G CARPARK)
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RISE AND FALL METHOD
Backsight Intermediate Foresight Rise Fall Reduced Level Remarks
1.290 100.000 BM 1
1.286 3.560 2.270 97.730 TP 1
1.391 1.278 0.008 97.738 TP 2
1.310 1.452 0.061 97.677 TP 3
1.445 1.389 0.079 97.598 TP 4
1.147 1.148 0.297 97.895 TP 5
1.259 1.200 0.053 97.842 TP 6
1.416 1.477 0.218 97.624 TP 7
1.194 1.225 0.191 97.815 TP 8
3.557 1.277 0.083 97.732 TP 9
1.354 1.297 2.260 99.992 TP 10
1.335 0.019 100.011 TP 11
16.649 16.638 2.775 2.764 100.011
- 16.638 -2.764 -100.000
0.011 0.011 0.011
Arithmetical Check :
∑ Backsight = 16.649, ∑ Foresight = 16.638, Last Reduced Level = 100.011, First Reduced
Level = 100.000
∑ Backsight - ∑ Foresight = Last Reduced Level – First Reduced Level
16.649 – 16.638 = 100.011 - 100.000
0.011 = 0.011
Acceptable Misclosure
12 ±√k, where k = number of set-ups
Misclosure = 12 ±√11
= 39,799 mm ( 0.039 m)
This error of misclosure is acceptable.
5.0 FIELD DATA
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COLLIMATION METHOD
Backsight Intermediate Foresight Collimation Reduced Level Remarks
1.290 101.290 100.000 BM 1
1.286 3.560 99.016 97.730 TP 1
1.391 1.278 99.129 97.738 TP 2
1.310 1.452 99.987 97.677 TP 3
1.445 1.389 99.043 97.598 TP 4
1.147 1.148 99.042 97.895 TP 5
1.259 1.200 99.101 97.842 TP 6
1.416 1.477 99.040 97.624 TP 7
1.194 1.225 99.009 87.815 TP 8
3.557 1.277 101.289 97.732 TP 9
1.354 1.297 101.346 97.992 TP 10
1.335 100.011 TP 11
16.649 16.638 100.011
-16.638 -100.000
0.011 0.011
Arithmetical Check :
∑ Backsight = 16.649, ∑ Foresight = 16.638, Last Reduced Level = 100.011, First Reduced
Level = 100.000
∑ Backsight - ∑ Foresight = Last Reduced Level – First Reduced Level
16.649 – 16.638 = 100.011 - 100.000
0.011 = 0.011
Acceptable Misclosure
12 ±√k, where k = number of set-ups
Misclosure = 12 ±√11
= 39,799 mm ( 0.039 m)
This error of misclosure is acceptable.
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FROM LEFT TO RIGHT : YAP CHOE HOONG, TANG LAM YU, TEE WAN NEE,
WONG SHER SHENG, TEO CHIANG LOONG
6.0 GROUP PHOTO
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In this levelling fieldwork, the reduced level of benchmark(BM) 1 is 100.00 mm. The
levelling process begins by recording the back-sight (BS) of BM 1 and the foresight (FS) of
turning point (TP) 1. After that we shift the auto level to obtain the back-sight of turning point
1 and the foresight of turning point 2. The process is repeated by shifting the auto level
from one point to another point. All the reading of back-sight and foresight are recorded for
calculation purpose.
After completed the fieldwork, we decided to use both the height of collimation and
rise and fall method to calculate the reduced level of each staff station. The error of
misclosure is 0.011mm. The maximum allowable error of closure is ±39.80mm. Thus, our
result is acceptable.
As a quantity surveyor, we have the responsibility to get the knowledge of site
surveying. We need to know because it is part of the construction process. For this
fieldwork, even though some errors occurred but we were able to do adjustment with the
help of our lecturer.
After the fieldwork have completed, we have learnt that group work and team
cooperation are vital in this fieldwork. The fieldwork could not be done smoothly if one of the
group member is absence. This fieldwork let us learn some hands-on knowledge where we
could not get it from the lecture. Lastly, we appreciate the help of our lecturer in this
fieldwork. We hope that we can get more opportunity in the future to get more hands-on
knowledge.
6.0 CONCLUSION AND DISCUSSION
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1. http://www.boeingconsult.com/tafe/ss&so/survey1/level/notes-sur1.htm
2. http://emmanuel-adukueaduku.blogspot.my/2012/08/levelling-is-name-given-to-
process-of.html
3. http://www.civilengineeringx.com/surveying/terms-used-in-levelling/
4. https://engineering.purdue.edu/~asm215/topics/difflevl.html
7.0 REFERENCES
