CONTENTS

CONTENT PAGE NUMBER

Cover page 1

Content 2

Objectives 3

Introduction 4-6

Apparatus Used for Levelling 7-9

Field Data 10-11

Adjusted Data 12-13

Two Peg Test 14

Summary 15

References 16

Objectives

● To allow us to have a better understanding or knowledge about the process of using the

instrument (Auto-level) rather than learning from a video in class.

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● To enable us to have the experience in using auto-level such as setting up,

collaborating, leveling and recording data.

● To apply the theories that had learnt in class.

● To know the precautions while using the Auto-level.

● To boost the teamwork while doing on fieldworks.

● To learn how to analyse the data.

● To enable us to have a basic knowledge on how to set up the points for leveling.

● To allow us to understand how to distribute different types of error from the data

collected on field.

● To allow us to experience and expose to the actual working environment in site such as

working under the hot weather.

● To determine the error of misclosure in order whether is it acceptable or not in the

levelling calculation.

Introduction to LevellingLevelling is the measurement of geodetic height using an optical levelling instrument, the object

of which is the elevations of given points with respect to a given or assumed datum, and to

establish points at a given or assumed datum. The first operation is required to enable the

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works to be designed while the second operation is required in the setting out of all kinds of

engineering works. Levelling deals with measurements in a vertical plane.

Why we need levelling?1) To find out the height of level in different points.

2) To collect data for the earthwork.

Define the name of points for levellingLevel surface: A level surface is defined as a curved surface which at each point is

perpendicular to the direction of gravity at the point. Any surface parallel to the mean spheroidal

surface of the earth.

Level line: A level line is a line on level surface.

Horizontal plane: Horizontal plane through a point is a plane tangential to the level surface at

that point. It is, therefore, perpendicular to the plumb line through the point.

Horizontal line: It is a straight line tangential to the level line at a point. It is also perpendicular

to the plumb line.

Vertical line: It is a line normal to the level line at a point. It is commonly considered to be the

line defined by a plumb line.

Datum: Datum is any surface to which elevation are referred. The mean sea level affords a

convenient datum world over, and elevations are commonly given as so much above or below

sea level. It is often more convenient, however, to assume some other datum, specially, if only

the relative elevation of points are required.

Elevation: The elevation of a point on or near the surface of the earth is its vertical distance

above or below an arbitrarily assumed level surface or datum.

Vertical angle: Vertical angle is an angle between two intersecting lines in a vertical plane.

Generally, one of these lines is horizontal.

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Mean sea level: It is the average height of the sea for all stages of the tides.

Bench-Mark: It is a relatively permanent point of reference whose elevation with respect to

some assumed datum is known. It is used either as a starting point for levelling or as a point

upon which to close as a check.

Two method of Leveling 1) Rise and fall method

2) Height of collimation

EXAMPLES:

1) Using Rise / Fall Method

B.S I.S F.S Rise Fall R.L Remarks

2.570 - - - - 100.00 A

3.750 - 1.200 1.370 - 101.37 C.P

- - 3.750 - 0.70 100.67 B

5.620 - 4.950 1.370 0.70 - -

● First reading is B.S and last reading is F.S. If you can’t get F.S as last reading on each

page, it means you are having mistakes.

● From the B.S next F.S is subtracted. If the answer is +ve it will be rise and if the answer

is -ve it be fall and put that reading in respective box.

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● In the above table, I have assumed that Reduce Level (R.L) of point A is 100.000 and

you can see R.L of point B is 100.670, which shows that point B is 0.670 units higher

than point A.

CHECKING

∑ (B.S) - ∑ (F.S) = ∑ Rise - ∑ Fall = R.L of last point - R.L of first point 5.620 - 4.950 = 1.37 -

0.70 = 100.670 – 100.000 = 0.67 = 0.67

2) Height of collimation Method (H.O.C)

R.L + B.S = H.O.C and H.O.C - F.S = R.L

B.S I.S F.S H.O.C R.L Remarks

2.50 - - 102.50 100.00 -

1.75 1 1.95 102.30 100.55 -

- 2.55 - - 99.75 -

- 2.70 - - 99.60 -

2.95 - 3.10 - 99.20 -

- - 2.75 - 99.40 -

7.20 - 7.80 - - -

CHECKING∑ (B.S) - ∑ (F.S) = R.L of last point - R.L of first point = 7.2 - 7.8 = 99.4 - 100 = -0.6 = -0.6

Apparatus Used for levelling

Automatic level

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The automatic level is used in measuring, surveying, and setting horizontal and vertical levels.

The instrument is normally situated on a tripod and then aligned to a leveled position using

leveling screws. The operator of the automatic level then looks through the telescope attached

to the instrument, while another person holds a graduated staff or tape measure at the position

under measurement.

Adjustable leg tripod

A surveyor's tripod is a gadget used to support any one of a number of surveying instruments,

such as theodolites, total stations, levels or transits. The surveyor will adjust on the legs'

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platforms to securely anchor the legs in soil or drive 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 generally

level. The mounting screw is pushed up under the instrument to connect the instrument's base

and screwed tight when the instrument is in the right position. The level surface of the tripod

head is known as 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.

Optical Plummet

In surveying, a device used in place of a plumb bob to center transits and theodolites over a

given point, preferred for its steadiness in strong winds.In addition if protect the instruments

falling down from accident.

Horizontal Bubble Level

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A bubble level is an instrument designed to indicate whether a surface is horizontal level or

vertical. You have to make sure that the bubble is in the circle to check the accuracy of a level.

Barcode Level Rod for Site Survey

It is made by wood or steel. It is used to determine the height of different points.

Field Data

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Field Data By Using Rise and Fall Method

Bench Mark(BM)

Back Sight(BS)

Fore Sight(FS)

Rise Fall Reduced Level(RL)

1.335 100.000

1 1.216 3.664 2.329 97.671

2 1.369 1.296 0.080 97.591

3 1.369 1.450 0.081 97.510

4 1.515 1.403 0.034 97.476

5 1.323 1.243 0.272 97.748

6 1.240 1.373 0.050 97.698

7 1.300 1.510 0.270 97.428

8 1.181 1.135 0.165 97.593

9 3.814 1.240 0.059 97.534

10 1.408 1.327 2.487 100.021

11 1.418 0.010 100.011

17.070 - 17.059

17.059 2.924 - 2.913

2.913 100.011 -100.000

0.011 0.011 0.011

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Field Data by Using Height of Collimation Method

Bench Mark(BM)

Back Sight(BS)

Fore Sight(FS)

Height of Collimation

Method

Reduced Level(RL)

1.335 101.335 100.000

1 1.216 3.664 98.887 97.671

2 1.369 1.296 98.960 97.591

3 1.369 1.450 98.879 97.510

4 1.515 1.403 98.991 97.476

5 1.323 1.243 99.071 97.748

6 1.240 1.373 98.938 97.698

7 1.300 1.510 98.728 97.428

8 1.181 1.135 98.774 97.593

9 3.814 1.240 101.348 97.534

10 1.408 1.327 101.429 100.021

11 1.418 100.011

17.070 - 17.059

17.059 100.011 -100.000

0.011 0.011

Accuracy limit = 12√k= 12√11= 0.039 m

Error = 100.011 - 100.000= 0.011 m

❖ Therefore, this levelling is acceptable.

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Adjusted Data

Adjusted Data by Using Rise and Fall Method

Bench Mark(BM)

Back Sight(BS)

Fore Sight(FS)

Rise Fall Reduced Level(RL)

Correction Adjusted Reduced

Level

1.335 100.000 100.000

1 1.216 3.664 2.329 97.671 0.001 97.670

2 1.369 1.296 0.080 97.591 0.002 97.589

3 1.369 1.450 0.081 97.510 0.003 97.507

4 1.515 1.403 0.034 97.476 0.004 97.472

5 1.323 1.243 0.272 97.748 0.005 97.743

6 1.240 1.373 0.050 97.698 0.006 97.692

7 1.300 1.510 0.270 97.428 0.007 97.421

8 1.181 1.135 0.165 97.593 0.008 97.585

9 3.814 1.240 0.059 97.534 0.009 97.525

10 1.408 1.327 2.487 100.021 0.010 100.011

11 1.418 0.010 100.011 0.011 100.000

17.070 -17.059

17.059 2.924-2.913

2.913 100.011 -100.000

100.000 -100.000

0.011 0.011 0.011 0.000

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Adjusted Data by Using Height of Collimation Method

Bench Mark(BM)

Back Sight(BS)

Fore Sight(FS)

Height of Collimation

Method

Reduced Level(RL)

Correction New Reduced

Level

1.335 101.335 100.000 100.000

1 1.216 3.664 98.887 97.671 -0.001 97.670

2 1.369 1.296 98.960 97.591 -0.002 97.589

3 1.369 1.450 98.879 97.510 -0.003 97.507

4 1.515 1.403 98.991 97.476 -0.004 97.472

5 1.323 1.243 99.071 97.748 -0.005 97.743

6 1.240 1.373 98.938 97.698 -0.006 97.692

7 1.300 1.510 98.728 97.428 -0.007 97.421

8 1.181 1.135 98.774 97.593 -0.008 97.585

9 3.814 1.240 101.348 97.534 -0.009 97.525

10 1.408 1.327 101.429 100.021 -0.010 100.011

1.418 100.011 -0.011 100.000

17.070 -17.059

17.059 100.011 -100.000

100.000 -100.000

0.011 0.011 0.000

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15 m

Two Peg Test

RA1= 1.296RB1= 1.218∆ hA1B1=1.296−1.218

= 0.077

RA2= 1.226RB2= 1.147∆hA1B1 =1.226-1.147

= 0.099

∴e = 0.099−0.07730

= 0.022 m over 30 m

Angle of elevation = tan−1 (o .022)(30)

= 00 ° 02 ' 31 ' '

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25 m

Instrument

Instrument

30 m

30 m

A B

A B

SummaryThe location of our field work 1 is located at Taylor’s University Lakeside Campus. In total, we

have 10 points located around to measure reduce level. The auto level was shifted around the

check point that had been set around the car park. While we are measuring, one of our member

are collecting the data.

In the Field work 1, we are using two methods which are Rise and Fall and Height of collimation

Method. In the levelling process, there is a mis-closure occur. The error of mis-clousure is 0.011

.Therefore, the levelling can be acceptable. After some discussion, we realised that the mis-

closure error was cause by the automatic level are not function well and our member did not

hold the bar-coded level rod properly.

The correction per set up is calculated to distribute the error. The correction is 0.001

per set up. We had adjusted the reduced level and the final reduced level so the final reduce

level is equivalent with the original given benchmark level.

In conclusion, all the data are accepted.

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References https://engineering.purdue.edu/~asm215/topics/levequip.html

http://www.aboutcivil.org/levelling-equipment.html

Photo of group members:

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Phon Kit Poi Ng Sheng Zhe

Sew Yue Ling Lieu Xue Qi

http://www.aboutcivil.org/levelling-equipment.html

https://engineering.purdue.edu/~asm215/topics/levequip.html

site survey fieldwork1 (levelling)

Education