SCHOOL OF ARCHITECTURE, BUILDING AND

DESIGN

BACHELOR OF QUANTITY SURVEYING (HONOURS)

Name Student ID Marks

Khoo Xin Yee 0316180

Lai Chun Foon 0315150

Hoo Bung Jiat 0314504

Kaligan 0305861

QSB1813 – Site Surveying

Field Work Report IITraverse Survey

August Semester 2015

Submission Date: 2nd July 2015

Content Page

Cover Page 1

Table of Content 2 - 3

1.0 Introduction to Traversing 4

1.1 Open Traverse 4

1.2 Closed Traverse 5 - 6

1.3 Northing 6 - 7

1.4 Azimuth 8

1.5 Bearing 8

1.6 Allowable Misclosure Traverse 9 - 10

1.7 Traverse Computation 11

2.0 Outline of Apparatus 12

2.1 Theodolite 12

2.2 Optical Plummet 13

2.3 Adjusted Leg-Tripod 14

2.4 Ranging Pole 15

2.5 Bull’s Eye Level 16

2.6 Plumb Bob 17

2.7 Measuring Tap 18

3.0 Objective 19

4.0 Field Data 20

4.1 Compute the Angular Angle and Adjust the Angle 21

4.2 Calculate the Horizontal and Vertical Distances

between the Survey Points and Theodolite

22 - 26

2

4.3 Compute the Course Bearing and Azimuth 27 – 28

4.4 Compute the Course Latitude and Departure 29 – 30

4.5 Determine the Error of Closure 31

4.6 Adjust Cours Latitude and Departure 32 – 33

4.7 Compute Station Coordinate 34

4.8 Loop Traverse Plotted Using Coordinate (Graph) 35

5.0 Conclusion 36 - 37

3

1.0 Introduction To Traversing

Traversing is a form of a control survey that requires the establishment of a

series of stations that are linked together by angles and distances. The angles

are measured by theodolites, and the distances are measured conventionally

by tapes or electronic distance measuring equipment. The use of theodolite in

traversing surveys is very fundamental and has become one of the most

common methods in geometric engineering work such as:

General purpose angle measurement;

Provision of control surveys;

Contour and detail mapping; and

Setting out and construction work.

There are two types of traverse:

1.1 Open Traverse

An open traverse originates at a starting station, proceeds to its destination,

and ends at a station whose relative position is not previously known.

The open traverse is the least desirable type of traverse because it provides

no check on fieldwork or starting data. For this reason, the planning of a

traverse always provides for closure of the traverse. Traverses are closed in

all cases where time permits.

Figure 1.0: Open Traverse

Source: http://www.oc.nps.edu/oc2902w/geodesy/geolay/images/gfl12ws.gif

4

1.2 Close Traverse

A closed traverse starts at a point and ends at the same point or at a point

whose relative position is known.

The surveyor adjusts the measurements by computations to minimize the

effect of accidental errors made in the measurements. Large errors are

corrected.

There are two types of closed traverse:

Loop Traverse - A loop traverse starts and ends on a station of

assumed coordinates and azimuth without affecting the computations,

area, or relative position of the stations.

If, however, the coordinates must be tied to an existing grid system, the

traverse starts from a known station and azimuth on that system. While

the loop traverse provides some check upon the fieldwork and

computations, it does not provide for a check of starting data or insure

detection of all the systematic errors that may occur in the survey.

Figure 1.1: Loop Traverse

Source: http://www.oc.nps.edu/oc2902w/geodesy/geolay/images/gfl12ws.gif

5

Connecting Traverse - It looks like an open traverse, except that it

begins and ends at points or lines of known position (and direction) at

each of the traverse.

Figure 1.2: Connecting Traverse

Source: http://www.globalsecurity.org/military/library/policy/army/fm/6-2/Ch5.htm

1.3 Northing

There are three reference directions or datum meridian that are used as

traverse reference we should be associated with. They are:

Magnetic North

Grid North

True North

1.3.1 Magnetic North

The earth has its magnetic field with its North and South poles in the vicinity of

the true positions of the North and South poles of the planet. This magnetic

field will orientate a free swinging magnetic needle in a north/south direction.

Based on this principle, it is therefore possible to orientate angular

measurements to magnetic north.

6

The magnetic north moves about the central axis of the earth. This variation is

known as “Magnetic Declination”. Magnetic Declination is the angular

difference between the true Whole Circle Bearing (WCB), measured relative

to true north and magnetic WCB, measured relative to magnetic north.

Magnetic declination varies according to the observer’s position relative to its

distance to the pole.

1.3.2 Grid North

It is a grid of lines parallel to the true meridian of one point on the grid, usually

the origin of the grid. Since the central meridian points to true north, therefore

as we move east or west away from the central meridian, the difference

between grid north and true north increases.

1.3.3 True North

This is the point at which all the lines of longitude converge (the axis of

rotation of the planet).

7

1.4 Azimuths

Azimuths defined as horizontal angles turned clockwise from the reference

line. These range from 0° > 360°. Generally measured only from the north.

(Preferred measurement)

Figure 1.3: Azimuth

Source: http://www.engr.mun.ca/~sitotaw/Site/Fall2007_files/Lecture9.pdf

1.5 Bearings

Bearings defined as an acute (less than 90°) horizontal angles measured from

the reference line. These are defined with two letters North (N) or South (S) &

West (W) or East (E) to indicate the quadrant containing the line. (Older

system difficult to adapt to computers)

Figure 1.4: Bearing

8

Source: http://www.engr.mun.ca/~sitotaw/Site/Fall2007_files/Lecture9.pdf

Assessment criteria for

Least Squares Adjustment

Assessment criteria for traverse computation

using Bowditch Rule

Class Class description

Allowable residual of

distance

measurement

Allowable residual of

angular

measurement

Allowable linear

misclosure

Allowable angular

misclosure

H1 Main Triangulation /

Trilateration

1: 120,000 2” --- ---

H2 Minor Triangulation /

Trilateration

1: 60,000 4” --- ---

H3 Main Control Traverse 1: 30,000 5” 1 : 30,000 5”√n

H4.1 Minor Control Traverse

(Class 4.1)

1: 15,000

or

5mm (minimum)

10” 1 : 15,000 10”√n

H4.2 Minor Control Traverse

(Class 4.2)

Note :

The origin of Class 4.2

1: 15,000

or

5mm (minimum)

10” 1 : 15,000 10”√n

H5 Traverse (Class 5) 1: 10,000

or

10mm (minimum)

20” 1 : 10,000 20”√n

H6 Traverse (Class 6) 1: 7,500

or

10mm (minimum)

30” 1 : 7,500 30”√n

1.6 Allowable Misclosure Traverse

Figure 1.5: Allowable Misclosure Traverse Table

Source: http://www.geodetic.gov.hk/data/specifications/Accuracy%20Standards%20of%20Control

%20Survey%20-%20Version%202.0.pdf

9

Class Class description Allowable difference between forward and backward run

Misclosure of level loop / level line

or

Residual of the height difference between stations V1 Precise Levelling

(Class 1)

4 √K mm when K ≥ 1

0.9 √N mm when K < 1

4 √K mm when K ≥ 1

0.9 √N mm when K < 1V2 Precise Levelling

(Class 2)

Note :

The origin of Class 2 benchmark network is determined by GNSS

4 √K mm when K ≥ 1

0.9 √N mm when K < 1

4 √K mm when K ≥ 1

0.9 √N mm when K < 1

V3 Ordinary Levelling 12 √K mm 12 √K mm

V4 Precise Levelling and

Trigonometrical Heighting

--- 12 √K mm

V5 Trigonometrical Heighting

(Class 5)

--- 30 √K mm

V6 Trigonometrical Heighting

(Class 6)

--- 50 √K mm

Figure 1.6: Allowable Misclosure Traverse Table

Source: http://www.geodetic.gov.hk/data/specifications/Accuracy%20Standards%20of%20Control

%20Survey%20-%20Version%202.0.pdf

10

1.7 Traverse Computation

Traverse computations is the process of taking field measurement through a

series of mathematical calculations to determine final traverse size and

configuration. These calculations include error compensation as well as

reformation to determine quantities not directly measured.

Traditional traverse computation steps are:

Step 1: Balance (adjust) angles

Step 2: Determine line directions

Step 3: Compute latitudes and departures

Step 4: Adjust the traverse misclosure

Step 5: Determine adjusted line lengths and directions

Step 6: Compute coordinates

Step 7: Compute area

The order of some steps can be changed. For example, steps 1 and 2 would

be reversed for closed link traverses with directions at both ends.  Balancing

angles would normally not be done if a least squares adjustment is used at

step 4.

The complete series of computations can only be performed on closed

traverses. That is because some of the steps require adjustment of errors and

errors cannot be identified in an open traverse.

2 .0 Outline Of Apparatus

2.1 Theodolite

11

Figure 2.0: Theodolite

Source: http://www.aliexpress.com/popular/surveying-theodolite.html

Theodolite is a precision instrument for measuring angles in the horizontal

and vertical planes. Theodolites are used mainly for surveying applications,

and have been adapted for specialized purposes in fields like meteorology

and rocket launch technology. A modern theodolite consists of a movable

telescope mounted within two perpendicular axes which are horizontal or

trunnion axis and the vertical axis. When the telescope is pointed at a target

object, the angle of each of these axes can be measured with great precision,

typically to seconds of arc.

Theodolite is a versatile instrument and is commonly used for the following

tasks:

a) Measurement of horizontal angles and vertical angles

b) Setting out horizontal angles

c) Ranging and Leveling

d) Optical distance measurement

e) Controlling verticality

2.2 Tribrach / Optical Plummet

12

Figure 2.1: Tribrach

Source: http://www.survey-acc.net/html_products/Tribranch-49.html#sthash.sdT2HjUG.dpbs

A tribrach is the detachable base of all theodolites, total stations, forced

centering targets, and most EDM’s. Tribrachs are equipped with a bulls eye

bubble for leveling and optical plummets for setting up precisely on a survey

mark. The discussion on tribrachs is conducted in a separate section because

they are being used with a wide variety of surveying equipment.

The ability to "leapfrog" backsight, instrument point and foresight by using

interchangeable tribrachs increases the speed, efficiency and accuracy of the

traverse survey. Whenever possible, the tribrach should be detached from the

instruments and placed on the tripods for either theodolite or EDM setups.

This procedure speeds up the setting up process and protects the instrument

from accidents. In some cases, the same tribrach can be used to perform

angular or distance measurements, as well as GPS observations from the

same survey point.

2.3 Adjustable Leg-Tripod

13

Figure 2.2: Tripod

Source: http://adainstruments.com/shop/tripods/surveying-tripods/surveying-tripod-ada-lightwood-s.html

Tripod provides a fixed base for all types of surveying instruments and

sighting equipment such as theodolites, total stations, levels or transits.

In the past, different equipment required different tripods. However, due to

standardization by instrument manufacturers, most of today’s equipment

utilize the same tripod. The same tripod can be used for total station, levels,

and GPS.

Tripods are made of either metal or wood. Wooden tripods are recommended

for precision surveys to minimize errors because of expansion and contraction

due to heat and cold. A stable tripod is required for precision in measuring

angles. A tripod should not have any loose joints or parts which might cause

instability.

2.4 Theodolite Pole / Ranging Pole

Figure 2.3: Theodolie Pole

14

Source: http://www.yorksurvey.co.uk/accessories/ranging-poles/1193/2m-steel-ranging-poles.html

Ranging poles are used to mark areas and to set out straight lines on the

field. They are also used to mark points that must be seen from a distance, in

which case a flag may be attached to improve the visibility.

Ranging poles are straight round stalks, 3 to 4 cm thick and about 2 m long.

They are made of wood or metal. Ranging poles can also be home made from

strong straight bamboo or tree branches.

Ranging poles are usually painted with alternate red-white or black-white

bands. If possible, wooden ranging poles are reinforced at the bottom end by

metal points

2.5 Bull’s Eye Level or Horizontal Bubble Level

Figure 2.4: Bull’s Eye Rod

15

Source: http://www.benchmarkarizona.com/Level_Rods-8-29.html

The bull's eye level is used for maintaining both level rods and sighting poles

in a vertical position. An out of adjustment bull's eye level can cause

accumulative error in level lines. Although the sighting pole is infrequently

used for traversing, an out of adjustment bull's eye level used on sighting

poles can cause errors in both angle and distance measurements.

A simple method for checking for gross error in bull's eye level adjustment is

to check it against a previously checked door jamb or other permanent

building part. Other, more elaborate, checking procedures can be developed

using plumb lines or other devices.

2.6 Plumb Bob

Figure 2.5: Plumb Bob

Source: http://www.snipview.com/q/Plumb-bob

Plumb bob is used to check if objects are vertical. A plumb bob consists of a

16

piece of metal (called a bob) pointing downwards, which is attached to a cord.

When the plumb bob is hanging free and not moving, the cord is vertical.

The plumb bob string with Gammon reel is the old standard short distance

sighting method, particularly for establishing temporary points. Steadiness of

the holder can be enhanced by the use of braces or any type of framework.

Various types of inexpensive string line targets are also available.

2.7 Measuring Tape

Figure 2.6: Measuring Tape

Source: http://www.harborfreight.com/1-2-half-inch-x-100-ft-open-reel-measuring-tape-36818.html

Surveying tapes are used in surveying to measure horizontal, vertical and

17

slope distances. They may be made of a ribbon or band of steel, an alloy of

steel, cloth reinforced with metal or synthetic materials. Tapes are issued in

various lengths and widths and graduated in a variety of ways. They are

available in lengths of 20, 30 and 50 m. Centimetres, decimetres and metres

are usually indicated on the tape.

Although EDM’s (electronic distance measuring instruments) have replaced

tapes for longer measurement, every crew should have both metallic and non-

metallic tapes available. Tape reels for metallic or fiberglass tapes save time

and help prevent damage to the tape, particularly if used in construction or

heavy traffic areas.

3.0 Objective

• To learn the principles of running a closed field traverse.

To enhance the students’ knowledge in the traversing procedure.

• To be familiar with the setting up and use of theodolite.

• To learn how to compute a traverse and properly adjust the measured

values of a closed traverse to achieve mathematical closure.

• To determine the error of closure and compute the accuracy of the

work.

• To be familiar with the various types and methods of traverse surveying

for detailing.

• To determine the adjusted independent coordinates of the traverse

stations so that they can be plotted on the drawing sheet.

18

4.0

Field Data

86°45’05’’93°47’25’’

92°40’25’’

B

A

D

C

48.8613 m

29.3505 m

47.4928 m

29.8862 m

N 0° 00’ 00’’ WField Data

Adjusted

86°47’05’’

19

Station Field Angles

A 86° 44’ 20’’

B 92° 39’ 40’’

C 86° 46’ 20’’

D 93° 46’ 40’’

Sum = 357° 175’ 120’’

359° 57’ 00’’

4.1 Compute the Angular Error and Adjust the Angles

The sum of the interior angles in any loop traverse must equal ( n - 2 )( 180° )

for geometric consistency.

Station Field Angle Correction Adjusted Angles

A 86° 44’ 20’’ + 0° 00’ 45’’ 86° 45’ 05’’

B 92° 39’ 40’’ + 0° 00’ 45’’ 92° 40’ 25’’

C 86° 46’ 20’’ + 0° 00’ 45’’ 86° 47’ 05’’

D 93° 46’ 40’’ + 0° 00’ 45’’ 93° 47’ 25’’

Sum = 357° 175’ 120’’ 360° 00’ 00’’

359° 57’ 00’’

20

Sum of interior = ( n - 2 )( 180° )

= ( 4 - 2 )( 180° )

= 360°

Total angular error = 360° - 359° 57’ 00’’

= 00° 03’ 00’’

Error per angle = 00° 03’ 00’’ / 4

= 00° 00’ 45’’ / 45’’ per angle

4.2 Calculate the Horizontal and Vertical Distance Between the

Survey Points and the Theodolite

The horizontal and vertical distances between the survey points and the

theodolite can be calculated using the equations as follows:

Equation

Where,

D = Horizontal distance between survey point and instrument

S = Difference between top stadia and bottom stadia

D = K × s × Cos2 (θ) + C × Cos (θ)

21

θ = Vertical angle of telescope from the horizontal line when

capturing the stadia readings

K = Multiplying constant given by the manufacturer of the theodolite,

(normally = 0)

C = Addictive factor given by the manufacturer of the theodolite,

(normally = 0)

Therefore,

Distance A - B

Distance A – B = [ K × s × Cos2 (θ) ] + [ C × Cos (θ) ]

= [ 100 × (1.680 – 1.130) × Cos2 (0) ] + [ 0 × Cos (0) ]

= 54.9916 m

Top Stadia: 1.680

Middle Stadia: 1.520

Bottom Stadia: 1.130

Top Stadia: 1.710

Middle Stadia: 1.463

Bottom Stadia: 1.280

22

Distance A – B = [ K × s × Cos2 (θ) ] + [ C × Cos (θ) ]

= [ 100 × (1.710 – 1.280) × Cos2 (0) ] + [ 0 × Cos (0) ]

= 42.7310 m

Average Reading = (54.9916 + 42.7310) ÷ 2

= 48.8613 m

Distance B - C

Distance B – C = [ K × s × Cos2 (θ) ] + [ C × Cos (θ) ]

= [ 100 × (1.415 – 1.085) × Cos2 (0) ] + [ 0 × Cos (0) ]

= 32.9950 m

Distance B – C = [ K × s × Cos2 (θ) ] + [ C × Cos (θ) ]

Top Stadia: 1.415

Middle Stadia: 1.270

Bottom Stadia: 1.085

Top Stadia: 1.520

Middle Stadia: 1.460

Bottom Stadia: 1.263

23

= [ 100 × (1.520 – 1.263) × Cos2 (0) ] + [ 0 × Cos (0) ]

= 25.7060 m

Average Reading = (32.9950 + 25.7060) ÷ 2

= 29.3505 m

Distance C - D

Distance C – D = [ K × s × Cos2 (θ) ] + [ C × Cos (θ) ]

= [ 100 × (1.710 – 1.220) × Cos2 (0) ] + [ 0 × Cos (0) ]

= 48.9925 m

Top Stadia: 1.710

Middle Stadia: 1.570

Bottom Stadia: 1.220

Top Stadia: 1.480

Middle Stadia: 1.320

Bottom Stadia: 1.020

24

Distance C – D = [ K × s × Cos2 (θ) ] + [ C × Cos (θ) ]

= [ 100 × (1.480 – 1.020) × Cos2 (0) ] + [ 0 × Cos (0) ]

= 45.9930 m

Average Reading = (48.9925 + 45.9930) ÷ 2

= 47.4928 m

Distance D - A

Distance D – A = [ K × s × Cos2 (θ) ] + [ C × Cos (θ) ]

= [ 100 × (1.723 – 1.423) × Cos2 (0) ] + [ C × Cos (0) ]

= 29.9954 m

Distance D – A = [ K × s × Cos2 (θ) ] + [ C × Cos (θ) ]

= [ 100 × (1.495 – 1.198) × Cos2 (0) ] + [ 0 × Cos (0) ]

Top Stadia: 1.723

Middle Stadia: 1.580

Bottom Stadia: 1.423

Top Stadia: 1.495

Middle Stadia: 1.350

Bottom Stadia: 1.198

25

= 29.7770 m

Average Reading = (29.9954 + 29.7770) ÷ 2

= 29.8862 m

4.3 Compute course bearing and azimuth

Azimuths Bearings

A – B 00° 00’ 00’’ N 00° 00’ 00’’

26

B – C 180° 00’ 00’’ N 87° 19’ 35’’ W

+ 92° 40’ 25’’

87° 19’ 35’’

Azimuths Bearings

C – D 92° 40’ 25’’ S 00° 32’ 30’’ W

+ 86° 47’ 05’’

179° 27’ 30’’

180° 00’ 00’’

- 179° 27’ 30’’

00° 32’ 30’’

27

D – A 93° 47’ 25’’ S 85° 40’ 05’’ E

+ 00° 32’ 30’’

94° 19’ 55’’

180° 00’ 00’’

+ 94° 19’ 55’’

85° 40’ 05’’

4.4 Compute Course Latitude and Departure

28

Figure 1.1: Algebraic sign convention for latitude and departure

Cos β Sin β L cos β L sin β

Station Bearing, β Length, L Cosine Sine Latitude Departure

A

N 00°00’00’’ 48.8613 1.0000 0.0000 + 48.8613 0.0000

B

N 87°19’35’’ W 29.3505 0.0466 0.9989 + 1.3691 - 29.3186

C

S 00°32’30’’ W 47.9428 0.1000 0.0095 - 47.9407 - 0.4532

29

D

S 85°40’05’’ E 29.8862 0.0755 0.9971 - 2.2574 + 29.8008

A

Total Perimeter (P)= 156.0408

Sum of Latitude:ΣΔy =0.0323

Sum of Departure:

ΣΔx =0.0290

4.4 Compute Course Latitude and Departure

4.5 Determine the Error of Closure

Error in departure

ΣΔx = 0.0290 mA

Total Error0.0434 m

Ec

30

Accuracy = 1 : (P/Ec)

For average land surveying an accuracy of about 1:3000 is typical.

Ec = [ (sum of latitude)2 + (sum of departure)2 ]1/2

= [ (0.0323)2 + (0.0290)2 ]1/2

= 0.0434 m

P = 156.0408 m

Accuracy = 1: (156.0408 / 0.0434)

= 1: 3595

Therefore, the traversing is acceptable.

4.6 Adjust Course Latitude and Departure

The Compass Rule

31

Correction = – [ ∑∆y ] / P x L or – [ ∑∆x ] / P x L

Where,

∑∆y and ∑∆x = The error in latitude and departure

P = Total length of perimeter of the traverse

L = Length of a particular course

Latitude Correction

The correction to the latitude of course A – B is

32

Station Unadjusted Corrections Adjusted

Latitude Departure Latitude Departure Latitude Departure

A

B

C

D

A

+ 48.8613

+ 1.3691

- 47.9407

- 2.2574

- 0.0000

- 29.3186

- 0.4532

+ 29.8008

-0.0101

-0.0061

-0.0099

-0.0062

-0.0091

-0.0054

-0.0089

-0.0056

+ 48.8512

+ 1.3630

- 47.9506

- 2.2636

- 0.0091

- 29.3240

- 0.4621

+ 29.7952

Σ= +0.0323 +0.0290 -0.0323 -0.0290 0.00 0.00CheckCheck

[ – 0.0323 / 156.0408 ] × 48.8613 = - 0.01011

The correction to the latitude of course B – C is

[ – 0.0323 / 156.0408 ] × 29.3505 = - 0.00608

The correction to the latitude of course C – D is

[ – 0.0323 / 156.0408 ] × 47.9428 = - 0.00992

The correction to the latitude of course D – A is

[ – 0.0323 / 156.0408 ] × 29.8862 = - 0.00619

Departure Correction

The correction to the departure of course A – B is

[ – 0.029 / 156.0408 ] × 48.8613 = - 0.0091

The correction to the departure of course B – C is

[ – 0.029 / 156.0408 ] × 29.3505 = - 0.0054

The correction to the departure of course C – D is

[ – 0.029 / 156.0408 ] × 47.9428 = - 0.0089

The correction to the departure of course D – A is

[ – 0.029 / 156.0408 ] × 29.8862 = - 0.0056

4.7 Compute station coordinates

Station N Coordinate* Latitude E Coordinate* Departure

A 100.0000 (Assumed) 129.3331 Start/return here for lat. check

33

B

C

D

A

+ 48.8512

148.8512

+ 1.3630

150.2142

- 47.9506

102.2636

- 2.2636

100.0000

- 0.0091

129.3240

- 29.3240

100.0000 (Assumed)

- 0.4621

99.5379

+ 29.7952

129.3331

Start/return here for dep. check

(Course lat. and dep.)

* Compass - Adjusted Coordinates

N2 = N1 + Lat1-2

E2 = E1 + Dep1-2

Where

N2 and E2 = The Y and X coordinates of station 2

N1 and E1 = The Y and X coordinates of station 1

Lat1-2 = The latitude of course 1-2

Dep1-2 = The departure of course 1-2

Figure 1.2: Table of Computation of Station Coordinate

4.8 Loop Traverse Plotted Using Coordinate (Graph)

34

5.0 Conclusion

In this second fieldwork, we were required to carry out a closed loop traverse

survey that is located at the car park. Closed loop traverse is a loop traverse

starts and ends at the same point, forming a closed geometric figure called a

polygon which is the boundary lines of a tract land. Before starting the

fieldwork, we roughly marked four points of stations which are station A, B, C

and D in a piece of paper. Station A, B, C and D must be stated on the site to

form a loop traverse.

After that, we used theodolite to measure the angles of four stations (A, B, C

and D) as our field data. The theodolite is placed at point A, and the angle of

point A is achieved by reading the theodolite through point D to B. The angles

of the theodolite must be read from left to right in order to obtain a more

accurate reading.

This process is repeated at each of the points on the site to obtain the angles

from each point. During the measurement, we recorded the vertical and

horizontal angles that have shown on the digital readout panel of the

theodolite.

We also recorded the top, middle and bottom stadia readings in order to

calculate the horizontal and vertical distances between the survey points

which are the distance between station A and B, station B and C, station C

and D and station D and A. This method is called stadia method.

D = K × s × Cos2 (θ) + C × Cos (θ)

During the process of calculating the error, we encountered our total field

interior angle is 359°57’00’’, which is 00°03’0’’ less than the standard total

interior angle of a polygon (360°). Thus, the error was distributed to each of

the point and each angle was added on with 00°00’45’’.

Our error in latitude is 0.0323 whereas the error in departure is 0.029. The

35

total error is 0.0434. By using the following formula, we calculated the

accuracy of our traverse survey.

Accuracy = 1: (P/EC), 1: [ Perimeter/ Error Closure ]

We obtained an accuracy of 1: 3595. For average land surveying an accuracy

of about 1:3000 is typical. Therefore, our traverse survey is acceptable. For

the adjustment of latitude and departure, we used the compass rule by using

the following formula:

Correction = - [ ∑Δy ÷ P ] x L or - [ ∑Δx ÷ P ] x L

After that, we computed stations coordinates and plotted all the stations by

using their coordinates in a graph paper.

Overall, this fieldwork has taught us a lot of hands-on knowledge about the

surveying. We are more understand that a land surveyor required to measure

distances in order to build level, sound buildings or determine the boundaries

of a piece of land. This profession, typically held by individuals with a degree

in civil engineering, is a very important one that has existed for all of recorded

human history.

Since distances can be distorted by hills and other factors, so a surveyor must

use several unique tools to acquire precise measurements. The profession of

surveying is commonly related to civil engineering, though surveying is an

important part of many academic disciplines. Surveyors have, and likely

always will be, an important part of developing infrastructure and maintaining

a civilized society.

36

37