Geomatics Laboratory
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U N I V E R S I T I P U T R A M A LAY S I A
FAKULTI KEJURUTERAAN
Faculty of Engineering
FACULTY OF ENGINEERING
DEPARTMENT OF CIVIL ENGINEERING
ECV 3511 GEOMATIC ENGINEERING
SEMESTER 1 2016/2017
LAB TITLE: levelling I - Establishment of Temporary Bench Mark
DATE OF PRACTICAL: 15 September 2016
GROUP NO.: 6
No. Matric No. Name Format Report
MARKS
1. 190968 MUHAMAD JAZMEER BIN Front Page
MAD JAIS 5
2. 190019 MUHAMMAD SOLIHUDDIN Table of Content, List of
Figure, List of Table
BIN USRI 5
3. 188861 AMIRUL DANIAL BIN Work of schedule
SAMSUDIN 5
Abstract/Introduction
4. 188103 LOK SZE WEI 5
Objective
5. 188835 AIN SHUHADA BINTI 5
HUSNI Equipment/Apparatus
5
6. 189151 NURUL HIDAYAH BINTI Methodology/Procedure
CHE YAHYA 10
Result & Calculation
NAME OF LECTURER: PROF. MADYA DR. 15
HELMI ZULHAIDI MOHD SHAFRI Discussion
15
Recommendations
NAME OF TEACHING ASSISTANT: MDM. 10
NURUL SUHADA MOHAMAD BASIR Conclusions
5
Bibliography
NAME OF ASSISTANT ENGINEER: MR. WAN 5
ZAKARIA WAN YUSOFF Appendices
5
DATE OF SUBMISSION: 6 October 2016 Effort
5
Total
100
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TABLE OF CONTENT
CONTENT PAGES
Table of Contents, List of Figures, List of Tables 1
Work of schedule 2
Abstract / Introduction 3
Objective 4
Equipment / Apparatus 5-6
Methodology / Procedure 7-9
Result and Calculation 10-12
Discussion 13
Recommendations 14
Conclusions 15
Bibliography / References 16
Appendices 17-18
LIST OF TABLE
CONTENTS PAGES
Apparatus used for levelling 5-6
Results for levelling 10
LIST OF FIGURE
CONTENTS PAGES
Flow chart of route plan 9
Figure of during levelling 17-18
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WORK OF SCHEDULED
LOK SZE WEI
1. FRONT PAGE
LOK SZE WEI
2. CONTENT
LOK SZE WEI
3. WORK OF SCHEDULE
LOK SZE WEI
4. INTRODUCTION
AIN SHUHADA BINTI HUSNI
5. OBJECTIVE
NURUL HIDAYAH BINTI CHE YAHYA
6. APPARATUS
NURUL HIDAYAH BINTI CHE YAHYA
7. METHODOLOGY
8. RESULT & MUHAMAD JAZMEER BIN MAD JAIS
CALCULATION
LOK SZE WEI
9. DISCUSSION
AMIRUL DANIAL BIN SAMSUDIN
10. RECOMMENDATIONS
AMIRUL DANIAL BIN SAMSUDIN
11. CONCLUSION
MUHAMMAD SOLIHUDDIN BIN USRI
12. BIBLIOGRAPHY
MUHAMMAD SOLIHUDDIN BIN USRI
13. APPENDICES
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INTRODUCTION
Levelling is the determination of the elevation of a point or difference between points
referenced to some datum. Datum is defined as an arbitrary level surface from which
elevation of points may be referred. A surveying operation carried out to determined the
elevation of points or to find the difference in elevation of points. The main equipment
needed to carry out levelling works are auto level and staffs. The elevation of the point is
calculated using Rise and Fall Method.
The purpose of the survey is to establish a new temporary bench mark (TBM) around
the engineering faculty as a precaution against the only site height reference being
disturbed or dug up part way through the contract.
During levelling, a bench mark (BM) which is a fixed reference point of known
elevation is used as the starting and finishing point. The first observation from the bench
mark is taken as the back sight (BS) of the bench mark after setup of instrument whereas
fore sight (FS) is the last staff reading taken denoting the shifting of the instrument. A
closed loop is made after the last reading is taken. The total distance of the closed loop is
calculated and recorded as K. Therefore, a new temporary bench mark (TBM) is
established after carried out the survey.
The National Mapping Council of Australia has published standard specifications and
recommended practices for vertical control surveys. The survey must conform to the third
order levelling which the misclosure limit is calculated using the formula ± (12√K) mm
(which is K = distance in km). Misclosure is the amount by which the measured height
difference differs from the known height. Small misclosures in closed level loops are
expected because of the accumulation of errors. Hence, the adjustment of misclosure is
carried out to remove the errors from the levelling process.
There are several errors found during the levelling process. Parallax errors,
collimation errors and temperature of staffs are some of the errors that be accumulated
throughout the survey.
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OBJECTIVE
The objectives of the levelling process are:
1. To establish new temporary bench mark (TBM).
2. To find the elevation of the given point with respect to the given or assumed datum.
3. To establish a point at a given elevation with respect to the given or assumed datum.
4. To make sure the land is in level does not have much difference in gradient.
5. To provide data for road cross-sections or volumes of earthworks.
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APPARATUS
Name of equipments and images Function
The staff is use to measure the height of
certain point.
1) 2 Staffs
To measure the distance at every point in
order to get the total distance.
2) Measuring tape
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An instrument to ensure the staff is erected
vertically. It is place at the side of staff.
3) 2 Bubble staffs
To get the reading of the height of certain
location or point.
4) Auto level and tripod
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METHODOLOGY
1. Choose a point from first temporary bench mark (TBM 1) and set up the tripod and
auto level (setup 1).
2. Make sure that the bubble at the auto level is in
the centre by adjusting the equipment.
3. A person must hold a staff at the temporary benchmark (TBM 1) and another person
must read the height of the benchmark (mark as back sight) using the auto level at
the setup 1 and measure the distance.
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4. Then, move the staff to change point 1 (CP 1). Measure the distance from setup 1 to
change point 1 and get the height of setup 1 (fore sight).
5. Move the auto level to setup 2. Measure the distance from setup 2 to the change
point 1 and get the height of the change point 1 (back sight).
6. Hold the staff at temporary benchmark 2 (TBM 2). Measure and record the distance
from TBM 2 to the setup 2 and read the height of TBM 2 (fore sight).
7. Move the auto level and make setup 3. Read the staff and get the height of TBM 2
(back sight) and measure the distance.
8. Hold the staff at change point 2 (CP 2). Get the height of change point 2 (fore sight)
using setup 3 and measure the distance measurement from setup 3 to change point 2.
9. Make setup 4, get the height measurement of the change point 2 (back sight) using
setup 4 and get the distance.
10. Move the staff and hold it at the first temporary bench mark (first point). Read the
height of TBM 1 ( fore sight) using setup 4 and measure the distance between them.
Close the loop
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TEMPORARY SETUP 1 change point 1
BENCHMARK BS FS
1
BS
TEMPORARY SETUP 2
BENCHMARK FS
2 SETUP 2
change point 2
SETUP 3
BS FS
BS
SETUP 4
FS
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RESULT AND CALCULATION
Results
BS IS FS RISE FALL Reduced Appr. Remarks
(m) (m) (m) (m) (m) Level (m) Dist. (m)
1.38 40 20.0 BM
1.52 1.53 0.15 39.85 55.0 CP1
1.27 1.28 0.24 40.09 48.3 TBM
1.37 1.37 0.1 39.99 51.0 CP2
1.35 0.02 40.01 32.0 BM
Ʃ5.54 Ʃ 5.53 Ʃ 0.26 Ʃ 0.25 Ʃ206.3
0.01 0.01 0.01
Misclosure Adjustment
Measured RL Point Adjustment Adjusted RL
(m) (m)
40 BM 0.00 40.00
39.85 CP1 0.003 39.847
40.09 TBM 0.005 40.085
39.99 CP2 0.008 39.982
40.01 BM 0.01 40.00
Rise & Fall Method
Rise or Fall = BS – FS
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Example
BS – FS = 1.38 – 1.53
= - 0.15m
When the value is negative, it will be written in the “fall” column.
BS – FS = 1.52 – 1.28
= 0.24m
When the value is positive, it will be written in the “rise” column.
Reduced Level (RL)
RL = Previous RL – Fall
RL = Previous RL + Rise
Example
RL = Previous RL – Fall
RL = 40.00 – 0.15
RL = 39.85m
RL = Previous RL + Rise
RL = 39.85 + 0.24
RL = 40.09m
Misclosure
Misclosure = ƩBS – ƩFS
Misclosure = 5.54 – 5.53
= 0.01 m
Allowed misclosure is ± (12√K) mm
K = Total distance (km) = 206.3m @ 0.2063km
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Allowed misclosure = ± (12√0.2063) mm
Allowed misclosure = 5.45mm
10mm > 5.54mm
The loop misclosure is larger than the misclosure limit. Hence, misclosure adjustment is
needed to eliminate the errors.
Misclosure Adjustment Calculation
RL － n (misclosure/Ʃn)
n = number of setup
Misclosure = value of loop misclosure
Ʃn = total of setup
Example
RL of CP1 = 39.85
Adjustment value = 1(0.01/4)
= 0.003
Adjustment RL = 39.85 – 0.003
= 39.847m
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DISCUSSION
The Temporary Bench Mark (TBM) has been held fixed at a Reduced Level (RL) of
40m. From there the back sight (BS) and fore sight (FS) are observed and recorded. Then,
the amount of rise and fall is gained from subtracted of BS with FS.
From the results above, the reduced level is being calculated through subtracting or
adding the rise and fall, a new reduced level is obtained. This process is then repeated for
several times from different points at the site. However, the final reduced level which is
40.01m is slightly more than the initial reduced level which is 40m. The slight difference
between the final reduced level and initial reduced level is 0.01m which is defined as
misclosure. By using the formula of calculating the misclosure limit, the maximum
allowable error is 5.45mm. Thus, there are some errors occurred during the levelling
process. Generally, errors cannot be totally eliminated, but they can be contained within
acceptable tolerances.
The errors that we made during the survey can be divided into three groups which are
instrumental errors, personal errors and errors due to natural causes. The instrument like
the auto level is not focused properly. Misfocussing and parallax error in the eyepiece
create accidental errors that cannot be corrected.
The unbalanced back sight and fore sight distances are also one of the errors that
accumulated during the survey. It is caused by the effect of curvature and refraction
errors. Readings that taken at a long distance will have a greater error than those at a
short distance. This unbalance may not be critical on one setup but can be compounded
into a considerable error if the unbalance continues over several setups.
One of the errors obtained due to natural causes is the effect of high winds and a
shining sun may result in a wrong staff reading. When the distance of sight is long. the
curvature of the earth may affect the staff reading.
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RECOMMENDATIONS
There are basically many ways that we can improve or reduce our errors in levelling
process. Here are some of the recommendations on how we can make our reading or the
process of levelling much accurate and less errors:
Use equipment which is well maintained or regularly checked and calibrated
Analyse acceptable error limit for each sources, resolve existing and underlying
errors.
Make sure that tripod and targets are mechanically sound and in adjustment.
If there is a strong wind, protect the instruments by shield or wait for reduce wind
speed.
Avoid different operators during observations procedure.
Temperature can cause uneven expansion of tripod and instruments parts resulting
in wrong staff readings. When this happen use umbrella.
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CONCLUSIONS
Based on our finding during the making of our temporary bench mark there are many
ways that we can reduce our errors and how we can make our reading more accurate.
Some of the ideas are already been stated in the recommendations section, there are ways
that we can improve our skills in levelling and how we manage to overcome the problems
that we face during the process.
This data that has been stated in the table consist of errors because there are no
accurate reading or measurements in levelling or surveying process. Therefore, there are
ways that can be done in order to calculate the errors and fix it. By using rise and fall
method, the misclosure can be obtained by subtracting and adding and calculations of the
data by using the misclosure formula. In the end of the process we manage to get the new
temporary bench mark (TBM).
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BIBLIOGRAPHY
INTERNET:
1. Retrieved from Surveying and Levelling,
http://www.civileblog.com/levelling/
2. Retrieved from Levelling Tutorial
http://www.levelling.uhi.ac.uk/
3. Retrieved from Geomatic Levelling
https://www.scribd.com/document/261201512/Geomatic-Levelling-Report
4. Retrieve from Geomatic Report
http://documentslide.com/documents/geomatic-levelling-report.html
BOOK:
1. W.SCHOFIELD , 2007 , Engineering Surveying , Edition Butterworth –
Heinemann : Linacre House , Jordan Hill , Oxford 2 8DP, UK
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APPENDICES
Photo 1: Holding the stuff straightly by using
bubble staff to ensure that the staff is vertical
when taking the readings.
Photo 2: Setting up the auto level at the Bench mark
(BS).
Photo 3: Adjusting the bubble of the auto level on
the centre to establish a horizontal plane.
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Photo 4: Observing the reading on the staff through the auto level.
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