sem 2 site surveying report 2

SCHOOL OF ARCHITECTURE, BUILDING AND DESIGN

BACHELOR OF QUANTITY SURVEYING (HONOURS)QSB60103103946-M Site Surveying

Fieldwork Report 2TRAVERSE

GROUP MEMBERS STUDENT ID

Liew Li Wen 0324297

Lim Kar Yan 0325602

Tan Hwee Min 0326057

Esther Chuah Ning Sie 0321422

TABLE OF CONTENT

Content PagesCover Page 1

Table of Content 2

Introduction 3 - 8

Objectives 9

Data and Results 10 - 22

Discussion 23 - 25

1

1.0 Introduction to traversing

Traversing is that type of survey in which a number of connected survey lines form the

framework and the directions and lengths of the survey lines are measured with the help of

an angle measuring instrument and a tape or chain respectively.

1.1 Types of Traverse

➔ Closed traverse: When the lines form a circuit which ends at the starting point, it is

known as closed traverse.

➔ Open traverse : When the lines form a circuit ends elsewhere except starting point, it

is said to be an open traverse.

1.11 Open Traverse

An open traverse is one which does not close on the point of the beginning. It begins at a

point of known position and ends at a station whose point is unknown. This traverse type is

not recommended because there is no geometric verification possible with respect to the

actual positioning of the traverse stations.It is commonly used for the line center survey for

highway,railroad and etc.

OPEN TRAVERSEImage source:www.artillerysurveyors131.com.au

1.12 Closed Traverse

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A closed traverse is one enclosing a defined area and having a common point for its

beginning and end point or at a point whose relative position is known. It is commonly used

for locating the boundaries of lakes,property and etc.

There are two types of closed traverse:-

1. Loop Traverse - The starting point and the ending point of the loop are located at the

same point, a closed geometric figure called a polygon will be formed. The ending

point will be the same with the beginning point if you were to move along the sides of

the closed traverse. Loop traverse are best surveyed in a counterclockwise

direction,with interior angles ‘turned’ to the right.

Image source:files.carlsonsw.com

2. 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 end of the traverse.

Deflection angles must be identified as being turned either clockwise,that is,to the

right (R) ,or counterclockwise to the (L).

Image source:jerrymahun.com

1.2 Azimuths

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The azimuth of a line defined as the clockwise horizontal angle from reference line. The

reference direction normally is from north .The range of the angle should be from 0º to 360º.

The example of the azimuth is 120º or 140º.

1.3 Bearing

A bearing of a line defined as the acute angle(<90º) from the north (N) or the south (S) end

of meridian. It has the addition designation of east (E) or west (W), whichever applies . The

angle of the bearing should never greater than 90º. The example of bearing is S60ºE or

N70ºW.

Image source:www.e-education.psu.edu

1.4 Selection of Traverse Stations

● The chosen control traverse stations need to be as close as possible to the features

or objects

● The chosen control traverse stations need to form a suitable shape.

● Cost and time of the survey will increase if too many points are established

● Sufficient control may not be provided for the survey if too few points are established.

● The ground of the survey area should be accessible where the traverse legs are

tapped.

● The length of the traverse legs are needed to be almost the same.

1.5 Acceptable Misclosure

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In common, for land surveying an accuracy of about 1:3000 is typical. The acceptable

misclosure can be calculated by using the formulae below:-

Accuracy= 1 : (P/Ec)

P= Perimeter

E= Error of closure (computed from the error in departure and error in latitude ,using the

Pythagorean theorem)

Classification First Order Second Order

(Class I)

Second Order

(Class II)

Third Order

(Class I)

Third Order

(Class II)

Recommended

spacing of

principal

stations

Network

stations 10-

15km ; other

surveys

seldom less

than 3km

Principal

stations

seldom less

than 4km,

except in

metropolitan

area

surveys ,wher

e the limitation

is

0.3 km

Principal

stations

seldom less

than 2km,

except in

metropolitan

area

surveys ,wher

e the

limitation is

0.2 km

Seldom less

than 0.1 km

in tertiary

surveys in

metropolitan

area

surveys ; as

required for

other surveys

Seldom less

than 0.1 km in

tertiary

surveys in

metropolitan

area surveys ;

as required

for other

surveys

Position

closure after

azimuth

adjustment

0.04m √K or1:100,000

0.08m √K or1:50,000

0.2m √K or1:20,000

0.4m √K or1:10,000

0.8m √K or1:5000

Table: Traverse Specifications - United States

Source: From Federal Control Committee,United States,1974.

1.6 Traverse Computations

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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:

1. Balance (adjust) angles

2. Determine line directions

3. Compute latitudes and departures

4. Adjust the traverse misclosure

5. Determine adjusted line lengths and directions

6. Compute coordinates

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's

because some of the steps require adjustment of errors and, as discussed before, errors

can't be identified in an open traverse.

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1.7 Outline Apparatus

Theodolites are used mainly for surveying applications. It is a

precision instrument for measuring angles in the horizontal and

vertical angles, distance, depth and etc. It is used to identify

the ground level and the ways to construct ‘super-structure or

sub-structure. A modern theodolite consists of a movable

telescope and it is able to rotate 360 degree on a tripod stand

by the leveling system. When the telescope is pointed at a

target object, the angle of each of these axes can be

measured with great precision. The calculation of the angles is

based on the used in triangulation network and geo-location

work.

Tripod stand consists of a portable three-legged frame. It is

used to provide stability by supporting the weight and

maintaining the balance of the instrument on top of it. The

three legs are moved away from the vertical centre and the leg

lengths are adjusted to bring the tripod head to a convenient

height and make it roughly level. After that screw the

instrument on it and make sure both of them are precisely

positioned.

Plumb bob is an instrument to make sure the object is

placed perpendicularly. It is a weight with a pointed

bottom that is suspended from a string to determine a

vertical line. It’s usually used to mark a point directly

under the theodolite.

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Spirit level is designed to indicate whether the surface is

horizontal or vertical. A slightly curved glass tube which

incompletely filled with either alcohol or spirit, leaving a

bubble in the tube. On a flat surface, the bubble naturally

rest in the center, the highest point.

Optical ‘plumnet is a detachable base for theodolites

to indicate the center of it over a ground station. It is

used in place of plumb bob to center theodolites and

transits over a given point due to its steadiness in

strong winds during surveying process. It can speed

up the set-up procedure and protect the theodolite

from any accident because there’s a lock below it to

screw itself towards the device using during the

fieldwork.

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 2m long. They are usually painted

with alternate red-white or black-white bands.

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2.0 Objectives

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

● To enhance the student knowledge in the traversing procedure

● To be familiar with the setting up of the theodolite

● To determine the error of misclosure in order to compute the accuracy of the work

● To determine the adjusted independent coordinates of the traverse station so that they

can be plotted on the drawing sheet

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3.0 Field Data

Station

A 82º 44’ 30’’

B 94º 39’ 50’’

C 87º 46’ 30’’

D 94º 46’ 50’’

Sum 359º 57’ 40’’

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3.1 Compute the angular error and adjust the angles.

The sum of the interior angles in any loop must be equal (n - 2) (180º) for geometric consistency;

Sum of interior angle= (n - 2) (180º) = (4 - 2) (180º) = 360º

Total angular error = 360º 00’ 00’’ - 359º 57’ 40’’ = 0º 02’ 20’’

Error per angle = 0º 02’ 20’’ / 4 = 0º 0’ 35’’ per angle

Station Angles Correction Adjusted Angles

A 82º 44’ 30’’ + 0º 0’ 35” 82º 45’ 05’’

B 94º 39’ 50’’ + 0º 0’ 35” 94º 40’ 25’’

C 87º 46’ 30’’ + 0º 0’ 35” 87º 47’ 05”

D 94º 46’ 50’’ + 0º 0’ 35” 94º 47’ 25”

Sum 359º 57’ 40’’ 360º 00’ 00”

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3.2 Calculate the Horizontal and Vertical Distance Between the Survey Points and the Theodolite

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;

D = k x S x cos2 (θ) + C x cos

Where,

D = Horizontal distance between survey point and instrument

S = Difference between top stadia and bottom stadia

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 b y the manufacturer of the theodolite

(normally = 0 )

Distance A-B

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Top Stadia: 1.730

Medium Stadia: 1.465

Bottom Stadia: 1.250

Top Stadia: 1.670



Distance A-B = [ (K x s x Cos2 θ) + ( C x Cos θ )= [ 100 x ( 1.730 - 1.250 ) Cos2 θ ] + ( 0 x Cos θ )

= 53.7742 m

Distance A-B = [ (K x s x Cos2 θ) + ( C x Cos θ )= [ 100 x ( 1.670 - 1.280 ) Cos2 θ ] + ( 0 x Cos θ )

= 45.5760 m

Average distance = ( 53.7742 m + 45.5760 m ) / 2 = 49.6751 m

Distance B-C

Top Stadia: 1.520



Top Stadia: 1.326



Distance B-C = [ (K x s x Cos2 θ) + ( C x Cos θ )= [ 100 x ( 1.520 - 1.263 ) Cos2 θ ] + ( 0 x Cos θ )

= 33.7420 m

Distance B-C = [ (K x s x Cos2 θ) + ( C x Cos θ )= [ 100 x ( 1.326 - 1.080 ) Cos2 θ ] + ( 0 x Cos θ )

= 24.7060 m


Distance C-D

13

Top Stadia: 1.490



Top Stadia: 1.620



Distance C-D = [ (K x s x Cos2 θ) + ( C x Cos θ )= [ 100 x ( 1.490 - 1.030 ) Cos2 θ ] + ( 0 x Cos θ )

= 49.7726 m


= 46.4762 m


Distance D-A

Top Stadia: 1.463



Top Stadia: 1.826



Distance D-A = [ (K x s x Cos2 θ) + ( C x Cos θ )= [ 100 x ( 1.463 - 1.189 ) Cos2 θ ] + ( 0 x Cos θ )

= 30.9954 m


= 31.9806 m


3.3 Compute course bearing and azimuth

14

Azimuth Bearing

A-B 00° 00’ 00” N 00° 00’ 00”

B-C 180° 00’ 00”+ 94° 40’ 25”_____________ 274° 40’ 25”_____________

N 85° 19’ 35” W

15

C-D 87° 47’05”+ 94° 40’ 25”____________ 182° 27’ 30”____________

182° 27’ 30”- 180° 00’ 00”____________ 2° 27’ 30”____________

S 2° 27’ 30” W

D-A 94° 47’ 25”+ 2° 27’ 30”____________ 97° 14’ 55”____________

180° 00’ 00”- 97° 14’ 55”____________ 82° 45’ 05”____________

S 82° 45’ 05” E

16

3.4 Compute Latitude and Departure

Image source:www.cfr.washington.edu

Cos β Sin β L cos β L sin β

Station Bearing, β Length, L Cosine Sine Latitude Departure

AN 00° 00’ 00” 49.6751 1.0000 0.0000 + 49.6751 0.0000

BN 85° 19’ 35” W 29.2240 0.0818 0.9967 + 2.3905 - 29.1276

CS 2° 27’ 30” W 48.1244 0.9991 0.0429 - 48.0811 - 2.0645

DS 82° 45’ 05” E 31.4880 0.1262 0.9920 - 3.9738 + 31.2361

A

Total Perimeter (P) = 158.5115Sum of Latitude:ΣΔy = 0.0107

Sum of Departure:ΣΔx = 0.0440

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3.5 Determine The Error of Closure

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 = [ ( 0.0107 )2 + ( 0.0440 )2 ]1/2

= 0.0453 m

P = 158.5115 m

Accuracy = 1 : ( 158.5115 / 0.0453 )

= 1 : 3499

Therefore, the traversing is acceptable.

3.6 Adjust Course Latitude and Departure

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The Compass Rule

Correction = - [ ΣΔy ] / P x L or - [ ΣΔx ] P / L

Where,

ΣΔy and ΣΔx = The error in latitude and departure

P = Total length of perimeter of the traverse

L = Length of a particular course

Station Unadjusted Corrections Adjusted

Latitude Departure Latitude Departure Latitude Departure

A+ 49.6751 0.0000 - 0.0034 - 0.0138 + 49.6717 - 0.0138

B+ 2.3905 - 29.1276 - 0.0020 - 0.0081 + 2.3885 - 29.1357

C- 48.0811 - 2.0645 - 0.0032 - 0.0134 - 48.0843 - 2.0779

D- 3.9738 + 31.2361 - 0.0021 - 0.0087 - 3.9759 + 31.2274

A

Σ= + 0.0107 + 0.0440 - 0.0107 - 0.0440 0.00 0.00

Check Check

19

Latitude correction

● The correction to the latitude of course A-B is

[ - 0.0107 / 158.5115 ] x 49.6751 = - 0.0034

● The correction to the latitude of course B-C is

[ - 0.0107 / 158.5115 ] x 29.2240 = - 0.0020

● The correction to the latitude of course C-D is

[ - 0.0107 / 158.5115 ] x 48.1244 = - 0.0032

● The correction to the latitude of course D-A is

[ - 0.0107 / 158.5115 ] x 31.4880 = - 0.0021

Departure correction

● The correction to the departure of course A-B is

[ -0.0440 / 158.5115 ] x 49.6751 = - 0.0138

● The correction to the departure of course B-C is

[ -0.0440 / 158.5115 ] x 29.2240 = - 0.0081

● The correction to the departure of course C-D is

[ -0.0440 / 158.5115 ] x 48.1244 = - 0.0134

● The correction to the departure of course D-A is

[ -0.0440 / 158.5115 ] x 31.4880 = - 0.0087

3.7 Compute station coordinates

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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

Station N Coordinate* Latitude E Coordinate* Departure

A 100.0000 ( Assumed )+ 49.6717

129.1495-0.0138 Start/ return here for lat. check

Start/ return here for dep. Check

(Course lat. and dep.)

B 149.6717+2.3885

129.1357-29.1357

C 152.0602-48.0843

100.0000-2.0779

D 103.9759-3.9759

97.9221+31.2274

A 100.0000 129.1495

* Compass - Adjusted Coordinates

Table 0f Computation of Station Coordinate

21

3.8 Loop Traverse Plotted Using Coordinate ( Graph)

The adjusted loop traverse plotted by coordinates.

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4.0 Discussion

In this field work, we are required to investigate the survey method which is the closed loop

traverse. A traverse is a series of consecutive lines whose ends have been marked on the

field, and whose lengths and directions (angle, bearing, or azimuth) have been determined

from measurements. There are two types of traverse which is the closed traverse and open

traverse. We found that the close traverse gives a higher accuracy because open traverse

offers no means of checking for errors or mistakes.

First, we are exposed to the method of using the apparatus which is the electronic distance

measurement (EDM). A detailed explanation has been given by our lecturer before the work

is conducted. Four points are roughly set and was noted as station A, B, C and D. These

four points are set to form a quadrilateral shape as we are conducting the simplest closed

loop traverse.

Then, we used the theodolite to measure the angle of the station A, B, C and D and the data

is recorded for further calculations. We first start with the angle measurement at station A.

The apparatus is set up at station A, the data is collected by reading through the theodolite

on station B and D. This step is repeated by setting the apparatus on the following stations

to obtain the angle on that particular station. Both vertical and horizontal angles which are

showed on the digital panel of the theodolite have been recorded.

The stadias (top, middle and bottom) readings are recorded for calculation of the horizontal

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and vertical distances between the stations. This is known as the stadia method. The

calculation is given by the equation:

D = k x S x cos2 (θ) + C x cos

When calculating the error, we have obtained 359º 57’ 40’’ for our total interior angle, which

is 2’ 20’’ less than the optimum total interior angle of a quadrilateral (360º). The optimum

total interior angle is calculated by

Σ=(n−2)∗180º

The error at each angle has been calculated and each angle is adjusted by adding 0º 0’ 35”.

Latitude and departure error is calculated then, which are 0.0107 and 0.0440 respectively. The total error is 0.0453 which is given by equation

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

And so, the accuracy is calculated with equation

Accuracy = 1 : (P/Ec)

The value obtained is 1:3499 which meets the optimum accuracy for average land surveying

1:3000 and hence, our traverse survey is acceptable.

Latitude and departure are then being adjusted by using the compass rule:

Correction = - [ ΣΔy ] / P x L or - [ ΣΔx ] P / L

Lastly, a graph is plotted with the coordinates achieved for all the four stations.

There are few precautions have to be taken in consideration when using the apparatus when

measurement is conducting.

1. Special care should be taken to avoid any situation that might result in the theodolite

24

being dropped or otherwise subjected to a severe jar.

2. Inspect the theodolite for loose parts and screws. Remove dust from the objective

lens and eyepiece with a lens brush and lens tissue using procedures consistent with

delicate optics. Keep the lens covered with the theodolite is not in use. Use a

sunshade to protect the lens from the direct rays of the sun.

3. The graduated circles and venires are coated with a lacquer to retard oxidation.

Avoid touching these parts. A thin film of oil applied with a lintless cloth will aid in

keeping the surfaces clean.

4. Store the theodolite in its case or other dry dust free location when not in use.

5. If the theodolite is to be taken from a cool environment to a warm one (especially in

humid conditions) allow the theodolite to warm up inside its case where it will not be

subject to condensation.

As any surveyor should understand, all measurements are in error. We may only try to

minimize error and calculate reasonable tolerances, but not eliminating the errors.

In conclusion, we have gained some useful knowledge on how a survey is done as it’s a

hand-on work that we have to conduct ourselves to obtain the data needed. It links up all the

theories we learned in class, giving us a deeper understanding as we worked practically on

field. It can be useful in the future as we know how a distance is measured in order to

construct a level building, or how a boundary of certain area is determined by this surveying

method.

It is pleased to have team members which are able to work together as a team in completing

the task given. The objectives set primarily are achieved easily since everyone in the team

gives fully support and cooperation throughout the survey work and report writing. Each

team members is willing to share their thoughts and ideas when discussion is conducted and

it’s a good attitude as we are able to learn from each other and broaden our mindset. Credits

are to be given to our lecturer as well for teaching and guiding us on how the survey work is

done and how the apparatus is used. It will be our pleasure if we are able to work together in

the next work soon.

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sem 2 site surveying report 2

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