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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 MARKS

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 Difference 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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RISE AND FALL METHOD

Backsight Intermediate Foresight Rise Fall Reduced

Level Correction Adjusted Reduced

Level Remarks

1.290 100.000 100 BM 1 1.286 3.560 2.270 97.730 - 0.001 97.729 TP 1 1.391 1.278 0.008 97.738 - 0.002 97.736 TP 2 1.310 1.452 0.061 97.677 - 0.003 97.674 TP 3 1.445 1.389 0.079 97.598 - 0.004 97.594 TP 4 1.147 1.148 0.297 97.895 - 0.005 97.89 TP 5 1.259 1.200 0.053 97.842 - 0.006 97.836 TP 6 1.416 1.477 0.218 97.624 - 0.007 97.617 TP 7 1.194 1.225 0.191 97.815 - 0.008 97.807 TP 8 3.557 1.277 0.083 97.732 - 0.009 97.723 TP 9 1.354 1.297 2.260 99.992 - 0.010 97.982 TP 10

1.335 0.019 100.011 - 0.011 100 TP 11 16.649 16.638

Correction per set-up :

Error of Misclosure / Number of set-ups = 0.011 / 11 = - 0.001 m

COLLIMATION METHOD

Correction per set-up :

Error of Misclosure / Number of set-ups = 0.011 / 11 = - 0.001 m

Backsight Intermediate Foresight Collimation

Reduced

Level Correction

Adjusted Reduced

Level Remarks

1.290 101.29 100.000 100.000 BM 1 1.286 3.560 99.016 97.730 - 0.001 97.729 1 1.391 1.278 99.129 97.738 - 0.002 97.736 2 1.310 1.452 99.987 97.677 - 0.003 97.674 3 1.445 1.389 99.043 97.598 - 0.004 97.594 4 1.147 1.148 99.042 97.895 - 0.005 97.890 5 1.259 1.200 99.101 97.842 - 0.006 97.836 6 1.416 1.477 99.040 97.624 - 0.007 97.617 7 1.194 1.225 99.009 97.815 - 0.008 97.807 8 3.557 1.277 101.289 97.732 - 0.009 97.723 9 1.354 1.297 101.346 97.992 - 0.010 97.982 10

1.335 100.011 - 0.011 100.000 11 16.649 16.638 100.011

-16.638 -100.000 0.011 0.011

5.0 ADJUSTED DATA

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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