ella fw 1.docx

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Mapúa Institute of Technology

Fieldwork no.1

CE121-OF/A2

Submitted by:

Ella, Carmela M.

Group No. 2

Student No.: 2011101507

Date of Fieldwork: February 04, 2014

Date of Submission: February 13, 2014 Grade

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Instructor: Engr. Bienvenido Cervantes

FIELD WORK NO.1

DETERMINATION OF PENTAGON AREA BY RADIAL TRAVERSING

AND AZIMUTH TRAVERSE USING TOTAL STATION

OBJECTIVES:

1. To acquire the knowledge in getting the area of a rectilinear field by staking station

on each corner points of a piece of land.

2. To learn how to read the horizontal angle of a theodolite.

3. To learn how to perform a closed azimuth traverse survey using theodolite and tape.

4. To develop the skills in the analysis of the area by DMD or DPD method.

5. To develop the ability to lead or to follow the designated/ desired task of one’s party

or group and to be fully responsible in the performance of the assigned task.

INSTRUMENTS:

INSRUMENT ILLUSTRATION USE

Total Station

Uses an incremental encoder to measure horizontal and vertical angles. The unique double-sided keypad allows for quick and easy readouts, displayed

brilliantly on LCD windows. The powerful 30X telescope optics produces

a crystal clear and bright image. An optical plummet, standard on the NETH 203, allows for fast and accurate setup.

Reflector Used over the years in nautical navigation devices and surveying

equipment.

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Chalk Used for marking tape ends and marking points during taping.

PROCEDURE:

A. Determination of the area of the rectilinear field by azimuth traversing.

1. The professor assigns the corners of the rectilinear field to be observed. These

points must be visible from each adjacent point and must be accessible for setting

the instrument. Drive on each corner hubs or mark each corner by a chalk if on

pavement. Name the points as stations T1, T2, T3, etc.

2. Set-up the theodolite on the 1st station. Orient the instrument to the magnetic south

after leveling. Note: Magnetic south is where the counter weight of the needle is

pointed when the telescope is in its normal position.

3. The tapeman must measure & record the distance from T1 to T2 and T1 to the last

station.

4. Set the horizontal vernier to zero reading. Preferably the instrument an must already

sketch the area to be traversed making remarks on the locations of each corner to

have an overview of the extent of the fieldwork.

5. Sight the next corner station T2 and record the azimuth reading in the horizontal

vernier. Compute also for bearing of this line.

6. Sight the last station and record the reading of the horizontal vernier for its back

azimuth to be used for checking the traverse later.

7. Transfer to the next station and follow the same procedure 2-5

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8. Follow the same procedure until you reach the last station.

9. For the double-checking of the work, it is also advised to record the interior angles of

all the vertices of the traverse station.

FINAL DATA SHEET

FIELD WORK 1

DETERMINATION OF THE RECTILINEAR AREA BY RADIAL TRAVERSE AND AZIMUTH TRAVERSE USING TOTAL STATION

DATE: 02/04/14 GROUP NO. 2TIME: 7:30 - 12:00 LOCATION: Mapua QuadrangleWEATHER: Sunny PROFESSOR: Engr. Bienvenido A. Cervantes

A. Azimuth Traverse

Data Sheet

STATION AZIMUTHTAPE

DISTANCE

BEARINGLATITUDE DEPARTURE

LAT(+) N

LAT(-) S

DEP(+) N

DEP(-) S

12 223°56’2”14.358

mN 43°56’02”

E10.34 9.96

23 291°5’50”17.893

mS 68°54’10”

E6.44 16.69

34 16°50’36”16.675

mN 16°50’36”

W15.96 4.38

45 80°47’21”14.480

mS 80°47’21”

W2.32 14.29

51 152°42’17”13.850

mS 41°17’43”

W14.38 7.53

B. Radial Traverse

STATION

AREA1 AREA2 AREA3 AREA4 AREA5

0 A=15.06 A=14.24 A=9.91 A=14.59 A=14.91

Total Area = 433.09 m2

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0 B=14.24 B=9.91 B=14.59 B=14.91 B=15.06

0Teta=63°21’

16”Teta=81°11’

40”Teta=89°49’

57”Teta=65°11’

40”Teta=59°38’

16”0 Area=95.84 Area=69.73 Area=72.29 Area=98.73 Area=96.87

Computations:

Total Area = 433.46 m2

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Sketch:

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OBSERVATION:

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The main objective of fieldwork no. 1 was to familiarize and learn how to use the

total station. Also, to be able to measure the area of pentagonal field using radial

transverse and azimuth transverse.

Since it was the first time for us to see the total station, it is privilege to our group to use

the total station for our field work. When we started the our field work, I observed that

every member of the group is first timers. Because of this, we had a hard time in

manipulating the total station but after we familiarize ourseleves with the instrument, our

work become easier and faster.

I also observed that the method of radial transversing is really fast and easy because all

we have to do is to set-up the center of the lot on which all points are clearly visible

without obstructions. Also, it is easier for us to measure the length of each point

because we all need to set up the instrument once. For me also, this fieldwork is not just

about the determinantion of the area lot but instead we used our knowledge in

determining the bearings and other components of triangles at the center of the lot.

Based on the data that we have gathered, we have measure a pentagonal lot with a

totl area of 433.09 square meters. Some errors we encountered during our fieldwork

were the instrument is not centered over point. Also, the unequal setting of tripod,

improper focusing of telescope and imperfect angle readings also affect our data.

DISCUSSION:

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In this field work, we are about to asked the area of the hexaganol plot by using

the DMD or DPD method by the use of total station. For us to solve the hexagonal lot,

we shoud able to know the length between the consecutive points and the bearing of

each points. Since we were asked to use the total station which most of us are first

timers in using that kind of instrument, it makes our field work easier and faster.

Because of that, we were not able to used the tape and solve for the bearing but instead

we just manipulate the instrument and the monitor will automatically display the bearing

and distance of the lot.

Given the distance and the bearing of the points that made up the lot, we can solve for

its area using the DMD or DPD method. The Total station will be placed on the first

point to find where the north side is. From the north side, the telescope will be rotated

to the next point in clockwise direction so that the bearing of the line will be solved

based on the data gathered. After that, the total station will be positioned on the next

point with the telescope sighting the previous point. After that, invert the position of the

telescope to find the back tangent and then sight the next point to find the deflection

angle. This deflection angles will be a great help in order to check whether the

measurements gathered are accurate. To check, the summation of all the deflection

angles should be 360 degrees. As we can see from the data that our group gathered,

the total of our deflection angles is 360 degrees so we can say that we have an

accurate measurement.

Since it was my first time used this instrument, I made myself familiarize to its buttons

and other parts. As time passes by, I learned how to manipulate it which makes our

work easier and faster. In using a total station, one should remember that the angle or

bearing produced is with respect to the south azimuth.

CONCLUSION/RECOMMENDATION:

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For the executed field work, I have learned that there are possible ways to find

the area of a polygonal lot. There were two ways that we performed in order to get its

area. The first one was called the azimuth traversing where we are able to use our

knowledge about measuring the latitude and departure of a certain point. After that, we

are to compute its DMD or DPD, then we are able to find the area of the lot. This

method gives an accurate answer for the area of the lot wherein the data are divided

into departures and latitudes. For the departure, the positive side is located on the east

side while the negative side is on the west side. For the latitude, the positive side is the

north side while the negative is on the south side. The other way is by radial traversing

where we now place a transit on the lot and we were able to measure from it its length

to the corner of the lot. There were triangles formed, so we are able to apply the

Heron’s formula, then add all the areas of the triangle to get the total lot area.

In this field work, we learned how to used the total station. This instrument is a great

help to us engineers and surveyors for this make the work done faster and easier. It

saves a lot of time and also give us an accurate measurement. The possible errors that

can contribute on the measurement given by the total station could be the human error

in which the positioning of the instrument can be a problem. For example, the plumb

bob connected to the total station is not centered on the point marked by chalk so that

contribute on the error of the field work.

Also, part of this field work, I learned how much team work is important in a group.

Everybody needs in a group, because each one of us must give an efforts for us to be

able to come up with a good results of the field work. Our confidence of being above to

other engineering students was boosted since now; we learned to use the total station

which they do not know.

We were able to meet the given objectives and adapt knowledge from the recent

fieldwork. Therefore, I conclude that azimuth and radial traversing are one of the best

and easy ways to calculate an area of a polygonal lot.

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RESEARCH:

Introduction to Azimuth and Bearing

In surveying, the direction of a line is described by the horizontal angle that it

makes with a reference line

This reference line is called a meridian. There are three types of meridians 

Astronomic - direction determined from the shape of the earth and gravity; also

called geodetic north

Magnetic direction taken by a magnetic needle at observer's position

Assumed - arbitrary direction taken for convenience .Methods for expressing the

magnitude of plane angles are: sexagesimal, centesimal, radians, and mils

Sexagesimal System - The circumference of circles is divided into 360 parts

(degrees); each degree is further divided into minutes and seconds

Centesimal System - The circumference of   circles is divided into 400 parts

called gon (perviously called grads)

Radian - There are 2pi radians in a circle (1 radian = 57.30 degrees)

Mil - The circumference of a circle is divided into 6400 parts (used in military

science)

Azimuths

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A common terms used for designating the direction of a line is the azimuth

The azimuth of a line is defined as the clockwise angle from the north end or

south end of the reference meridian.

Azimuths are usually measured from the north end of the meridian

Every line has two azimuths (forward and back)

and their values differ by 180 degrees

For example: the forward azimuth of line AB is

50 degrees- the back azimuth or azimuth of BA is

230 degrees

Azimuth are referred to astronomic, magnetic, or

assumed meridians

Bearing

Another method of describing the direction of a line is give its bearing

The bearing of a line is defined as the smallest angle which that line makes with

the reference meridian

A bearing cannot be greater than 90 degrees (bearings are measured in relation

to the north or south end of the meridian - NE, NW, SE, or SW

Reference meridian may be astronomic, magnetic, or assumed

It is convent to say: N90E is due East

S90W is due West

Until the last few decades American surveyors favored the use of bearings over

azimuth

However, with the advent of computers and calculators, surveyors generally use

azimuth today instead of bearings

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Traverse

A traverse is a series of successive straight lines that are connected together

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A traverse is closed such as in a boundary survey or open as for a highway

An interior angle is one enclosed by sides of a closed traverse

An exterior angle is one that is not enclosed by the sides of a closed traverse

An angle to the right is the clockwise angle between the preceding line and the

next line of the a traverse

A deflection angle is the angle between the preceding line and the present one

Traverse Computations

If the bearing or azimuth of one side of traverse has been determined and the

angles between the sides have been measured, the bearings or azimuths of

the other sides can be computed

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One technique to solve most of these problems is to use the deflection angles

 Example - From the traverse shown below compute the azimuth and bearing of side BC 

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Example - Compute the interior angle at B

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