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Introduction

Traverse survey is a series of indivisible points at which angles are measured

and between the distances measured. There are 3 types of traverse, they are closed

polygonal traverse, closed link traverse and open traverse.(n.a. ,2013)

In this field work we were told to construct a four sided polygon and measure

the length and angle of the polygon. In order to carry out our field work the equipment

we used where the Ranging rod, Automatic level (dumpy level), tripod, measuring

tape and a plumb bob.


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Equipment

Ranging Rod

The base of the ranging are mostly made by wood or steel. (Ahmad, 1996) Thenumber of section of the rod are normally 2 or 3 and the diameter of the rod is 1.5mm.

(Ahmad, 1996) Most of the ranging rod was PVC coated so that it is more durable

and weather resistant.

Figured 10: Ranging rod

Normally ranging rod is used for calculating direction and angle.

Autom at ic Level (Dumpy Level)

Dumpy level look like a telescope and the way of using it is almost the same. Usually

it is set-up on a tripod. A levelling staff or rod is needed when calculating level plan

using automatic level. (McCormack, 1997) When using automatic level, make sure it

is true horizontal. (McCormack, 1997) Generally there are three adjustable screw-feet

to adjust the automatic level to horizontal. Staff bubble is used to determine thehorizontality of the automatic level. Figured 2 show an image of an automatic level


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Figured 2: Automatic level (McCormack, 1997)

Base on Rolf Moody procedure of using automatic levelFirst, setup a tripod on aground as level as possible, then screw the automatic level on top of the tripod. Afterthat, adjust the bubble inside the staff bubble to the centre, then make sure thecrosshair and the objective lens are perfectly clear. (Rolf, 2008)

Tripod

Figured 3: Tripod (Milligan, 2002)

The above diagram shows a standard tripod used in levelling. They are design insuch it is very stable and help surveyor to have more accurate reading. The leg of the

tripod is adjustable to duel with uneven ground level. A clamp or a screw is used tolock the leg of the tripod after adjusted.


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Figured 6: Clamp (left) and Screw (right) (Milligan, 2002)

Make sure the leg is been tighten, because any slight movement of the tripod it have

to set up again and all the recorded value are no long can be use due to the height of

the instrument had change.(Milligan, 2002)

Staf f B ubble

Basically it is use for make sure the equipment like levelling staff and automatic levelare held vertical. (Wong, 2013) To reduce

error. When the bubble are in the circle at

the centre which means the equipment

are vertical. Figured 7 shows a staff

bubble.

Figured 7: Staff Bubble (Wong, 2013)


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Plumb bobs

A plumb-bob is usually a heavy metal with a sharp bottom and attach to a string used

as a reference point. (Boeing, 2003) It is tied to the bottom of automatic level making

sure that the automatic level is at the exactly position or mark the position. (Boeing,2003) It also help maintain the height of the instrument. Figured 8 is an example of a

plumb-bob

Figured 8: Plumb-bob (Boeing, 2003)

Measurin g Tape

Measuring tape is used to measure the distance between one points to other. Usually

Fibre glass tape is used because it is more durable and accurate. (Nosek, 1968)

Figured 9: Fibre glass tape (Nosak, 1968)


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3.0 Results/Data

Figure 1

Station Angle Course Length, H (m)

A 64 AB 4.356B 113 BC 7.540

C 38 CD 6.086

D 144 DA 4.548

Table 1 Table 2


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Formula: ( ) Correction of Angle =

Latitude, Y = H cos (WCB)Departure, X = H sin (WCB)

Precision Error =

() ()

Where,

N = Number of SideH = Distance / Length of SideW.C.B = Whole Circle Bearing = AzimuthW = Course AB/BC/CD/DA


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4.0 Discussions

According to Merriam-Webster, 'error of closure' is define as the sum of the angles of

a traverse as measured minus the true sum required by geometry - called also

closing error. The true sum of quadrilaterals should be 360. However, the totalinterior angles obtained is 359which is 1 lesser than the true sum of the quadrilateral.

Therefore, an error of closure has occurred.

There are many reasons that affect the error for the result of the survey such as

human error. transposition of numbers, neglecting to level an instrument, misplacing

a decimal point, misunderstanding a callout, back sighting an incorrect turning point

or control point, not extending the level rod the full length for a high rod

reading.("Chapter 4 Errors and Maximum Closures", 2005)

In addition to that, other types of error which can also happen, such as systematic

error that is an error that is not determined by chance but is introduced by an

inaccuracy (as of observation or measurement) inherent in the system. ("Systematic

error - Definition and More from the Free Merriam-Webster Dictionary", 2013) Next,

random errors are a measurement mistake caused by the factors that vary from one

measurement to another; a statistical error due to chance. ("Random error | Define

Random error at Dictionary.com", 2013).

Moreover sources of error can come from 'Personal Error', 'Instrument Error' and

'Natural Error'. Personal error is due to physical limitations and observing habit of the

observer. ("Chapter 4 Errors and Maximum Closures", 2005) Instrument error is

caused by imperfections in the design construction and adjustment of instruments

and other equipments. ("Chapter 4 Errors and Maximum Closures", 2005) Lastly,

natural error is sourced by natural physical conditions such as atmospheric pressure,

temperature, humidity, wind, gravity and atmospheric refraction. ("Chapter 4 Errorsand Maximum Closures", 2005)

The errors can be corrected by carrying out adjustment by equally balancing the

interior angles and using the 'Compass Rule' as shown in the calculations below.


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Figure 2

( ) ( )

|

|

Station Field Angle Arbitrarily Balanced Equally Balanced

A 64 64 6415B 113 11330 11315

C 38 38 3815D 144 14430 14415 359 =360 =360

Error = 1= 60 Balanced BalancedCorrection of Angle =

=

15Table 3

In this report, the method of equally balancing every interior angle in the field isadopted.


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Calculations of the Azimuth AB, BC, CD and DA are shown below:

Figure 3

Course Adjusted Interior Angle Azimuth

AB 6415 13515BC 11315 6830CD 3815 28645DA 14415 251

Table 4

WCB AD 71 6415

WCB AB 13515 11315

24830 180WCB BC 6830

381510645

180WCB CD 28645

14415431

180WCB DA 251


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Calculations of Latitude and Departure are shown below:

Course Distance, H Azimuth Bearing Latitude Departure

AB 4.356 13515 S 4445E -3.094 3.067BC 7.540 6830 N 6830E 2.763 7.015

CD 6.086 28645N 7315

W 1.754 -5.828

DA 4.548 251 S 71W -1.481 -0.430 P = 22.530 lat = -0.058 dep = -0.046

Table 5

For AB,

Latitude, Y = 4.356 cos (13515) = -3.094Departure, X = 4.356 sin (13515) = 3.067

For BC,

Latitude, Y = 7.540 cos (6830) = 2.763Departure, X = 7.540 sin (6830) = 7.015

For CD,Latitude, Y = 6.086 cos (28645) = 1.754Departure, X = 6.086 sin (28645) = -5.828

For DA,Latitude, Y = 4.548 cos (251

) = -1.481

Departure, X = 4.548 sin (251) = -0.430

Calculating Precision Error,

Precision Error =

() () () ()

P = 22.530Precision Error =

=

The ratio of error is small.


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Distributing errors in latitude/departure by using Compass Rules:(Answers are corrected to 4 significant figures)

Correction for error in latitude, , where W = any course

()

()

()

()

Correction for error in departure,

, where W = any course

()

()

()

()


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Coordinates Latitude Correction of Error Adjusted Latitude, x

Xa -3.0940 0.0112 -3.0828

Xb 2.7630 0.0194 2.7824

Xc 1.7540 0.0157 1.7697

Xd -1.4810 0.0117 -1.4693

= 0

Table 6

Coordinates Departure Correction of Error Adjusted Departure, y

Ya 3.0670 0.0089 3.0759

Yb 7.0150 0.0154 7.0304

Yc -5.8280 0.0124 -5.8156

Yd -4.3000 0.0093 -4.2907 = 0

Table 7

Since x +y = 0,The coordinates are adjusted correctly.


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Let Station B to be (1000.00 N, 1000.00 E).

(Answers are corrected to 4 significant figures)

Xa= 1000.0000 - 3.0759 = 996.9241 EYa= 1000.0000 + 3.0828 =1003.0828 N

Xb= 1000.0000 E Yb= 1000.0000 N

Xc= 1000.00 + 7.0304 = 1007.0304 EYc= 1000.0000 + 2.7824 =1002.7824 N

Xd= 1007.03045.8156 = 10001.2148E

Yd= 1002.7824 + 1.7697 =1004.5521 N

Figure below shows the traverse station coordinates by using balanced latitudes anddepartures.

Figure 4

The actual coordinates of Station A, B, C and D are tabulated in the table below:

Stations

Coodinates

X Y

A 996.92 E 1003.08 N

B 1000.00 E 1000.00 N

C 1007.03 E 1002.78 N

D 1001.21 E 1004.55 N

Table 8


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5.0 Graph:


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Conclution

With travesing survey


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References

Ahmad, Saleem. "Survey Equipment." IndiaMART - Indian Manufacturers Suppliers

Exporters Directory,India B2B Exporter Manufacturer. Taj Survey Industries, 1996.

Web. 03 Dec. 2013.

Boeing, Karl. "SURVEYING EQUIPMENT AND LEVEL SET-UP." Building &Construction Information. Boeingconsult, 2003. Web. 28 Nov. 2013..

Chapter 4 Errors and Maximum Closures. (2005).Errors and Maximum Closures.

Error of closure - Definition and More from the Free Merriam-Webster Dictionary. (2013).

In Dictionary and Thesaurus - Merriam-Webster Online. Retrieved from

http://www.merriam-webster.com/dictionary/error%20of%20closure

Error of closure -Definition and More from the Free Merriam-Webster Dictionary.(2013). InDictionary and Thesaurus -Merriam-Webster Online. Retrieved from

http://www.merriam-webster.com/dictionary/error%20of%20closureMcCormack, AJ. "Setting out Auto-levels & Lasers." Pavingexpert. N.p., 1997. Web.

28 Nov. 2013. .

Milligan, Sean R. "Level and Tripod." Levelling Tutorial 1. Uhi.ac.uk, Nov.-Dec. 2002.Web. 28 Nov. 2013. .

Nosek, Aaron. "Long Tape." Make Your Mark. Keson, 1968. Web. 28 Nov. 2013..

Random error | Define Random error at Dictionary.com. (n.d.). InDictionary.com.Retrieved from http://dictionary.reference.com/browse/random+error

Retrieved fromhttp://www.mdt.mt.gov/other/survey/external/survey/manual_guides_forms/survey_manual/sm_chapter04.pdf

Retrieved December 1, 2013, from

http://faculty.mu.edu.sa/public/uploads/1334330566.8372traverses[1].pdfRolf, Moody, and Murphy Phil. "How To Use Auto Levels." New England Laser &

Transit Company: Lasers, Optics, Sales, Rentals, Service. NewEnglandLaser.com,

2008. Web. 28 Nov. 2013.

.

Systematic error -Definition and More from the Free Merriam-Webster Dictionary.(n.d.). InDictionary and Thesaurus -Merriam-Webster Online.RetrievedDecember3, 2013, from http://www.merriam-webster.com/dictionary/systematic+error? show=0&t=1386092850Wong, Khai Jee. "Levelling." Site Surveying. Taylor's Lakeside University, SubangJaya. 11 Sept. 2013. Lecture.
http://www.levelling.uhi.ac.uk/tutorial1_1.htmlhttp://faculty.mu.edu.sa/public/uploads/1334330566.8372traverses%5b1%5d.pdfhttp://faculty.mu.edu.sa/public/uploads/1334330566.8372traverses%5b1%5d.pdfhttp://faculty.mu.edu.sa/public/uploads/1334330566.8372traverses%5b1%5d.pdfhttp://www.levelling.uhi.ac.uk/tutorial1_1.html

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