Fieldwork 2 (Traversing)
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Transcript of Fieldwork 2 (Traversing)
SCHOOL OF ARCHITECHTURE, BUILDING AND DESIGN
BACHELOR OF QUANTITY SURVEYING
FIELDWORK 2
TRAVERSING
NAME STUDENT ID
STEVEN CHAN KAI TIONG 0319850
TAY SY MIN 0320813
VOON SZE LUN 0315032
WONG GENG SEN 0321690
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Content
Content Pages
Cover page 1
Content page 2
Introduction 3
Outline Apparatus 4 - 6
Objective 7
Tabulation Data 8
Adjustment Data 9 - 11
Conclusion 12
Reference s 13
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Introduction
Traverse survey
- Traversing is one kind of method that used in the field of surveying to establish control networks. A traverse is a series of straight lines that are used to connect a series of selected points. These selected points are called traverse stations where distance and angle measurements are made. The relative positions of the traverse stations are then computed using some coordinate systems.
2 types of traverse survey: closed traverse and open traverse.
1. Closed traverse: this traverse starts at a point and ends at the same point. Areas that are suitable for locating are lakes, woods, and for survey of large areas.
2. Open traverse: this traverse originates at a starting station, then proceeds to its destination, and then ends at a station whose relative position is not previously known. This traverse is suitable for surveying a long narrow strip of land.
The least desirable type of traverse is the open traverse because this traverse provides no check on fieldwork or starting data. Because of this, the planning of a traverse always provides for closure of the traverse. So, the traverses are closed in all cases where time permits. Those surveyors adjust the measurements by computations to minimize the effect of accidental errors made in the measurements and the large errors are corrected.
Source from: http://www.floridageomatics.com/publications/gfl/chapter-three.htm
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Outline Apparatus
Theodolite - is an instrument that used to measure angles and directions. It's mounted on an adjustable tripod and has a spirit level to show when it is horizontal.
Tripod
- is a device used to support any one of a number of surveying instruments, such as theodolites, total stations, levels or transits.
Horizontal bubble level
- is an instrument used to indicate the horizontal level. It is a slightly curved glass tube which is incompletely filled with alcohol.
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Plumb bob
- is a weight which is suspended from a string and used as a vertical reference line. Set the instrument exactly over a fixed survey marker, or to transcribe positions onto the ground for placing a marker.
Theodolite pole
- used as a stand to indicate the angle
between two or more points in an enclosed area.
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Theodolite
All theodolites have the same common features which can be described as follows:
1. Targeting sight
2. Objective lens
3. Horizontal clamp knob
4. Horizontal tangent screw
5. Display window
6. Operating keys
7. Levelling screws
8. Tripod base plate
9. Optical plummet
10. Instrument centre mark
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Objectives
1. To allow student to have a better understanding on the process of using theodolite rather
than listening to the lecture in class.
2. To allow student to gain experience on how to use theodolite, for example: setting up,
collaborating, calculating and recording data.
3. To enable student to know the methods of measuring the angles and lines.
4. To enable student to know the precautions that should be taken while using the
Theodolite.
5. To allow student to have the experience of doing fieldwork under actual working
environment in site such as working under the hot weather.
6. To allow student to understand the importance of teamwork while carrying out the
fieldwork.
7. To determine how to analyse the data collected from the fieldwork.
8. To allow student to understand how to distribute different types of error from the data
collected on field.
9. To enable student to learn how to read the positions on ranging rods.
10. To enhance the knowledge on how to set up the points for the fieldwork.
11. To allow student to have the ability to finish the site measurements and calculations
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Field Data
Station Field Angles
A 89°07’ 20”
B 92° 24’ 40”
C 88° 45’ 00”
D 89° 55’ 20”
Sum 360° 12’ 20”
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A89°07’ 20” B
92° 24’ 40”
D89° 55’ 20”
28.35 m
62.24 m
29.51 m
61.60 m
C88° 45’ 00’’
AUNGULAR ERROR AND ANGULAR ADJUSTMENTS
(4-2)(180°) = 2(180°) = 360° , the sum of interior angles of the traverse must be 360°.
Hence, total angle errors = (360° 00’ 00’) - (360° 12’ 20’’) = -0° 12’ 20’’
Therefore, error per angle = (-0° 12’ 20’’)/4 = -0° 3’ 5’’
Station Field Angles Correction Adjusted Angles
A 89°07’ 20” -0° 3’ 5” 89° 4’ 15”
B 92° 24’ 40” -0° 3’ 5” 92° 21’ 35”
C 88° 45’ 00” -0° 3’ 5” 88° 41’ 55”
D 89° 55’ 20” -0° 3’ 5” 89° 52’ 15”
Sum 360° 12’ 20” 360° 00’ 00”
Station Adjusted Angles Course Azimuths
A-B 89° 4’ 15” 89° 4’ 15”
B-C 92° 21’ 35” 89° 4’ 15” + 92° 21’ 35” - 180° = 1° 25’ 50’’
C-D 88° 41’ 55” 1° 25’ 50” + 88° 41’ 55” + 180° = 270° 7’ 45’’
D-A 89° 52’ 15” 270° 7’ 45” + 89° 52’ 15” - 180° = 180° 0’ 0’’
Computation for course azimuths
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Computations for Latitude and Departure
Length Cos β Sin β L cos β L sin βStation Azimuth, β L(m) Cosine Sine Latitude Departure
A89° 4’ 15” 61.60 +0.0162 +0.9999 +0.9989 +61.5919
B1° 25’ 50” 28.35 0.9997 +0.0250 +28.3412 +0.7078
C270° 7’ 45” 62.24 +0.0023 -1.0000 +0.1403 -62.2398
D180° 0’ 0” 29.51 -1.0000 0.0000 -29.5100 0.0000
APerimeter(P) = 181.70 m Sum of latitudes = ∑∆y = -0.0296 m
Sum of departures = ∑∆x = 0.0599m
Error in departure ∑∆x = 0.0599 m
Error in latitude
∑∆y = -0.0296 m
Accuracy = 1: (P/Ec)
Therefore, the accuracy = 1: (181.70/0.0668)
= 1: 2720.05988
= 1: 2700
For average land surveying an accuracy of about 1: 3000 is typical.
Hence, the accuracy of field is acceptable.
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Total Error = 0.0668m
Adjusted Course Latitudes and Departures
Unadjusted Corrections Adjusted
Station Latitude Departure Latitude Departure Latitude DepartureA
+0.9989 +61.5919 0.0101 -0.0203 +1.0090 +61.5716B
+28.3412 +0.7078 0.0046 -0.0093 +28.3458 +0.6985C
+0.1403 -62.2398 0.0101 -0.0205 +0.1504 -62.2603D
-29.5100 0.0000 0.0048 -0.0098 -29.5052 -0.0098A
Sum -0.0296 0.0599 0.0296 -0.0599 0.0000 0.0000
Computation of Station Coordinates
Assume that the coordinates of A is (100.000, 100.000)
Station Adjusted Latitude
Adjusted Departure
N Coordinate Latitude
E CoordinatesDeparture
A 100.000 100.000+1.0090 +61.5716
B 101.0090 161.5716+28.3458 +0.6985
C 129.3548 162.2701+0.1504 -62.2603
D 129.5052 100.0098-29.5052 -0.0098
A 100.00 100.000
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Correction in Latitude of AB = Total LatitudeMisclosureTraverse Perimeter
× Lengt hof AB
Correction in Departure of AB = Total Departure Misclosure
Traverse Perimeter× Lengthof AB
Summary
In this fieldwork, a theodolite is being used. There were only four theodolite in the campus hence we shared the theodolite with another group and used the pacing method to obtain our length of each course but we failed to get an accuracy of at least 1:3000. After that, we used the tape-measure the length of each course. In order to get the most accurate reading possible, our lecturer, Mr. Chai taught us to use the theodolite to guide our tape-measure to make it is in as straight line.
Our error in departure is 0.0599 and our error in latitude is -0.0274. The total error is 0.0659. Using the following formula, we calculated the accuracy of our traverse survey:
Accuracy = 1: Perimeter/ Error Closure
We obtained an accuracy of 1:2700. For average land surveying an accuracy of 1:3000 is typical. Therefore, our traverse survey is acceptable.
The result of this fieldwork is interesting and satisfying. Thank to our lecturer, Mr. Chai who taught us how to do the fieldwork and helped us to gain some knowledge on how to use a theodolite so we can do the fieldwork smoothly and successfully.
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Reference
Bob Vila (n.d.). The Plumb Bob. (Website). Retrieved on 20 November 2014 from
http://www.bobvila.com/articles/495-the-plumb-bob/#.VHbzzTGLUeoh
EngineerSupply, LLC © Copyright 1999-2015. (Website)
http://www.engineersupply.com/theodolites.aspx
Federal Geodetic Control Committee (1984). Standard Specifications for Geodetic Control Networks. Retrieved on 20 November form
http://www.ngs.noaa.gov/FGCS/tech_pub/1984-stda-specs-geodetic-control-networks.pdf
Farlex clipart collection. © 2003-2012 Princeton University, Farlex Inc.
http://www.thefreedictionary.com/ranging+rod
http://nptel.ac.in/courses/105107122/modules/module9/html/28-5.htm#
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