SCHOOL OF ARCHITECTURE, BUILDING AND DESIGN BACHELOR OF QUANTITY SURVEYING (HONOURS) QSB60103103946- M Site Surveying Fieldwork Report 2 TRAVERSE GROUP MEMBERS STUDENT ID Liew Li Wen 0324297 Lim Kar Yan 0325602 Tan Hwee Min 0326057 Esther Chuah Ning Sie 0321422
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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
2
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
3
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
4
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
5
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.
6
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.
7
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.
8
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
9
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’’
10
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