Complete Traverse Report

TRAVERSE INTRODUCTION: INTRODUCTION:

A traverse is a survey where the boundaries of something is established or set up. In survey explanation, traverse is defined as the field operation of measuring the lengths and directions of a series of straight lines connecting a series of points on the earth. Each of these straight lines is called a traverse leg, and each point is called a traverse station or control point.

Traverse can be divided into two types, open traverse and closed traverse. Open traverse do not close or end at a point of known coordinates which should be avoided in conducting traversing. Closed traverses are consecutive lines that begin and end in points of known coordinates. When the starting and ending points are the same, we may refer it as loop traverse.

The accuracy of traverses is dependable to the instruments or equipment and measuring techniques. For first class traverse, the maximum misclosure or allowable

misclosure is 1’15” and the fractional error is 1:8000. However, for second class traverse, the maximum misclosure is 2’30” and the fractional linear error is 1:4000. The control traverse we conducting should be a first class traverse.

OBJECTIVE:

To make a traverse survey, reduce the field data and plot the results graphically.

APPARATUS: a) Total station b) Tripods c) Prisms d) Nails e) Hammer f) Wooden pegs

PROCEDURE:

1. The total station is plumbed and accurately leveled over the point 20. The prisms are set up at point 21 and peg 1.

2. Point 21 is sighted on face left of the theodolite set to the required horizontal angle. The reading is filled in the field book.

3. The theodolite is turned anti-clockwise to peg 1 and peg 1 is sighted to get the horizontal angle.

4. The instrument is then set face right by transiting the telescope and point 21 is sighted again.

5. Peg 1 is sighted and the reading is taken.

6. Distance is measured by using the digital theodolite with centre collimated and the reading is tabulated in the field book.

7. The total station is then moved to peg 1 and a new peg 2 is made. The prisms are putted at point 20 and peg 2.

8. Point 20 is sighted on face left with theodolite and reading is taken.

9. Procedures 3 to 7 are repeated using the same pattern until the total station is plumbed at point 20. 1) Calculate L and D , 006 . 0   L m 020 . 0   D m 2) Convert to polar (θ , L)           L D 1 tan           006 . 0 020 . 0 tan 1  " 7 . 2 ' 18 73    As it is at 4th quadrant, thus " 00 ' 00 360 " 7 . 2 ' 18 73     

2 2 L D L  

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 

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3) calculate linear error, e and fractional error,

Linear error, e D2 L2

e

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Fractional linear error =        e DISTANCE : 1 =       021 . 0 688 . 560 : 1 = 1:26699.43

DISCUSSION:

1. The survey plan for the control traverse is drawn in A4 size paper.

2. The sources of errors that may arise when measuring traverse angles is discussed.

There are three types of errors that may arise when we measuring the control traverse errors.

First and foremost, instrument error could be the one which affect the reading taken. Instrument error such as plate bubble out of adjustment, vertical axis not horizontal to horizontal axis, and vertical circle index errors will causes inaccuracy and imprecision of angles measured. Usually this error occurred when the instrument have been used for many times or some technical problems in making the instrument.

Secondly is the natural error which is inevitable. One example of natural error is the wind. The blowing of wind due to rotation of earth will cause vibration to the instruments which causes inconsistency in reading of the instruments. Besides wind, temperature also will affect the traverse angle measured. Under a hot sun, unequal expansion may occur at many parts of the instruments such as the lenses, prisms and so on. Moreover, different density of atmosphere may cause diffraction where the observer tends to have sight readings different from the actual readings.

Lastly is the personal error or human error caused by careless of human when conducting the control traverse. For example, the instrument is not set up exactly on the point or the datum. This may affect the horizontal readings. Next, the bubble of the total station is not centered. Sometimes the observer tends to neglect the position of eyes when centering the bubble. The eyes must perpendicular to the bubble so that parallax error can be avoided. Besides, the poor focusing of the observer also will affect the readings. Some observers who wear spectacles tend to have some problems in focusing at the prism or looking at the telescope. Thus, gross error may occur. Moreover, careless in plumbing and placement of tripod or rod by human where only the top can be seen by instrument operator due to the obstacle in the way.

CONCLUSION:

According to our results, our value is and our distance is 0.021m. Our misclosure is 0 00’45” which do not exceed our allowa le misclosure for class one, 0 01’15”. However, the fractional error calculated is 1:2989.213 which is not the first class value 1:8000. Errors may occur during the experiments.

REFERENCES:

1. 1991, Jack C. Mccormac, Surveying Fundamentals, Second Edition 2. 2010, John Uren and Bill Price,Surveying for Engineers, Fifth Edition