SCHEDULING ON TRANSPORTATION FOR INDUSTRIALIZED BUILDING
SYSTEMS
FOONG KOK LI
This project report is submitted as a fulfilment of the
requirements for the award of the degree of
Master of Science (Construction Management)
Faculty of Civil Engineering
Universiti Teknologi Malaysia
APRIL 2006
PSZ 19:16 (Pind. 1/97)
UNIVERSITI TEKNOLOGI MALAYSIA
BORANG PENGESAHAN STATUS TESIS♦
JUDUL :
SCHEDULING ON TRANSPORTATION FOR
INDUSTRIALIZED BUILDING SYSTEMS
SESI PENGAJIAN : 2005 / 2006
FOONG KOK LI
Saya
(HURUF BESAR)
mengaku membenarkan tesis (PSM/Sarjana/Doktor Falsafah)* ini disimpan di Perpustakaan
Universiti Teknologi Malaysia dengan syarat-syarat kegunaan seperti berikut:
1.
2.
Tesis adalah hakmilik Universiti Teknologi Malaysia.
Perpustakaan Universiti Teknologi Malaysia dibenarkan membuat salinan untuk tujuan
pengajian sahaja.
Perpustakaan dibenarkan membuat salinan tesis ini sebagai bahan pertukaran antara
institusi pengajian tinggi.
** Sila tanda ( √ )
3.
4.
√
SULIT
(Mengandungi maklumat yang berdarjah keselamatan atau
kepentingan Malaysia seperti yang termaktud di dalam
AKTA RAHSIA RASMI 1972)
TERHAD
(Mengandungi maklumat yang TERHAD yang telah ditentukan
oleh organisasi/badan di mana penyelidikan dijalankan)
TIDAK TERHAD
Disahkan oleh
(TANDATANGAN PENULIS)
(TANDATANGAN PENYELIA)
Alamat Tetap:
88, JALAN KELAPA BALI,
TAMAN SOGA
83000 BATU PAHAT, JOHOR.
Tarikh:
28 April 2006
CATATAN: *
**
♦
PROF. MADYA DR. ABDUL KADIR
MARSONO
Nama Penyelia
Tarikh:
28 April 2006
Potong yang tidak berkenaan.
Jika tesis ini SULIT atau TERHAD, sila lampirkan surat daripada pihak berkuasa/organisasi
berkenaan dengan menyatakan sekali sebab dan tempoh tesis ini perlu dikelaskan sebagai
SULIT atau TERHAD.
Tesis dimaksudkan sebagai tesis bagi ijazah Doktor Falsafah dan Sarjana secara penyelidikan,
atau disertai bagi pengajian secara kerja kursus dan penyelidikan, atau Laporan Projek
Sarjana Muda (PSM).
Status Declaration Letter
Date : April, 2006
Librarian
Perpustakaan Sultanah Zanariah
UTM, Skudai
Johor
Sir,
CLASSIFICATION OF THESIS AS RESTRICTED
SCHEDULING ON TRANSPORTATION FOR INDUSTRIALIZED
BUILDING SYSTEMS
FOONG KOK LI
Please be informed that the above mentioned thesis entitled “SCHEDULING ON
TRANSPORTATION FOR INDUSTRIALIZED BUILDING SYSTEMS” be
classified as RESTRICTED for a period of three (3) years from the date of this letter.
The reasons for this classification are
(i)
(ii)
(iii)
COMMERCIALIZATION OF RESEARCH PRODUCT
NEGOTIATION STAGE WITH UTSB SDN. BHD AS BUSINESS
CONSULTANT
NICHE IBS PRODUCT COMPONENT ARE WAITING TO BE
MANUFACTURED
Thank you.
Sincerely yours,
ASSOC. PROF. DR. ABDUL KADIR MARSONO
M46-238
07-5531606
013 7257737
“I/We* hereby declare that I/we* have read this project report and in my/our*
opinion this project report is sufficient in terms of scope and quality for the award of
the Master of Science (Construction Management)”
Signature
: ………………………………
Name of Supervisor I
: PM. DR. ABDUL KADIR MARSONO
Date
: 28 APRIL 2006
Signature
: .………………………………
Name of Supervisor II : DR. MASINE MD. TAP
Date
* Delete as necessary
: 28 APRIL 2006
ii
I declare that this project report entitled “Scheduling On Transportation for
Industrialized Buildings Systems” is the result of my own research except as cited
in the references. The project report has not been accepted for any degree and is
not currently submitted in candidature of any other degree.
Signature
:
………………………………
Name
:
FOONG KOK LI
Date
:
28 APRIL 2006
iii
Dedication
To my beloved father and mother
iv
ACKNOWLEDGEMENT
At first, I would like to express my sincere appreciation to my supervisor,
Associate Professor Dr. Abdul Kadir Marsono for his guidance and
encouragement. Without his guidance and support, this project would not have
been completed.
Other than that, I am also very grateful to my parents and friends for their
support and encouragement throughout this project. I would to thank Mr Cheng
from Country View Sdn Bhd for giving me the key plan and architectural drawings
for the shop houses at Taman Universiti.
v
ABSTRACT
Now, the construction is facing the challenges from the four main aspects,
which are quality, cost, time and safety. However, by implementing the
industrialized building system (IBS), all those challenges can be faced easily. In this
study, double storey shop houses will be used as a model to illustrate the
management of IBS transportation for fabricators. Besides, the number of trucks
required each day will be discussed here based on proper scheduling using project
management software. Other than that, this study focuses on the scheduling by
optimization. This project highlights a proper management of the trucks used in the
delivery of IBS components for construction.
vi
ABSTRAK
Kini, industri pembinaan sedang menghadapi cabaran daripada empat aspek
iaitu kualiti, kos, masa dan, keselamatan. Namun demikian, melalui pelaksanaan
sistem bangunan secara berindustri (IBS), semua cabaran dapat dihadapi dengan
mudahnya. Dalam kajian ini, rumah kedai dua tingkat akan digunakan sebagai model
untuk mengilustrasi pengurusan bagi pengangkutan IBS untuk pembuat-pembuat
IBS. Selain itu, bilangan trak yang diperlukan bagi setiap hari akan dibincangkan
bergantung kepada penjadualan yang sistematik dengan penggunaan pengurusan
projek perisian. Di samping itu, kajian ini menumpu kepada penjadualan dengan
menggunakan kaedah optimum. Projek ini menitikberatkan pengurusan yang
sistematik dalam penghantaran komponen IBS untuk pembinaan.
vii
TABLE OF CONTENTS
CHAPTER
CHAPTER I
CHAPTER II
TITLE
PAGE
TITLE OF PROJECT
i
DECLARATION
ii
DEDICATION
iii
ACKNOWLEDGEMENTS
iv
ABSTRACT
v
ABSTRAK
vi
INTRODUCTION
1
1.1
Introduction
1
1.2
Problem Statement
3
1.3
Objectives
4
1.4
Scope of Study
4
1.5
Significant of the Study
4
LITERATURE REVIEW
6
2.1
6
Definition of Industrialization
viii
2.2
Characteristics of Industrialization
6
Process
2.3
Industrialized Building Systems
7
2.3.1 Advantages of Industrialized
8
Building Systems
2.3.2
Limitations of Industrialized
9
Building Systems
2.3.3 Aspects Considered in the
11
Selection of an Industrialised
System
2.3.4
Precast Units
12
2.4
Materials Management
13
2.5
Just-in-time Management
15
2.5.1
15
Principles of Just-in-time
Management Philosophy
2.5.2
2.6
JIT and Lean Production
17
Production Management
21
2.6.1
Classification of Inventories
23
2.6.2
Cost of Keeping Inventory
23
2.7
Prefabrication Planning
24
2.8
Transportation of Precast Components
26
2.8.1
Precast Concrete Handling
28
2.8.2
Unloading at Site
29
Production Planning and Control
29
2.9.1
Process Planning
30
2.9.2
Loading
30
2.9.3
Scheduling
31
2.9.4
Project Planning Methods
32
2.9
ix
2.9.5
Planning in the Delivery and
33
Erection
CHAPTER III
2.10
Facility Management
34
2.11
Queing Theory
36
2.12
Optimization
40
METHODOLOGY
43
3.1
Introduction
43
3.2
Selection on Type of Buildings
43
3.3
Determination Location of Study
43
3.4
Data Sources
44
3.5
Determination Location and Number of
44
Shop Houses
3.6
Determination of Precast Components
44
3.7
Scheduling Demands for Precast
44
Components
CHAPTER IV
3.8
Transportation Scheduling
45
3.9
Analysis
45
3.10
Conclusion
45
RESULTS AND ANALYSES
47
4.1
Introduction
47
4.2
Problem Definition
47
4.3
Benefits of Scheduling
48
x
4.4
Scheduling Software
49
4.5
General Description
51
4.5.1
Description of Site
51
4.5.2
Description of Fabrication Plant
52
4.5.3
Description of Shop Houses
52
4.6
Scheduling Demand at Site
53
4.6.1
Assumptions
53
4.6.2
Detail Scheduling of Demands at
54
Site
4.7
Transportation Scheduling
61
4.7.1
Assumptions
61
4.7.2
Detail Scheduling of
62
Transportation
4.8
Analysis
69
4.8.1
Case 1: 50 km Distance
70
4.8.1.1 Time Estimation
70
4.8.1.2 Rescheduling (50 km)
73
Case 2: 100 km Distance
96
4.8.2.1 Time Estimation
97
4.8.2.2 Rescheduling (100 km)
99
Analysis Cases of Transportation
111
4.8.2
4.8.3
Break Down
4.8.3.1 Analysis for Case 100 km
111
4.8.3.2 Analysis for Case 50 km
114
xi
CHAPTER V
CONCLUSION AND SUGGESTION
119
5.1
Introduction
119
5.2
Discussion on the Study
119
5.3
General Conclusion
121
5.4
Suggestions for Future Study
121
123
REFERENCES
APPENDICES
Appendix A
125
Appendix B
132
Appendix C
133
Appendix D
134
Appendix E
138
Appendix F
142
xii
LIST OF TABLES
TABLE NO.
2.1
TITLE
Relative Advantage and Disadvantage of
PAGE
10
Industrialization Under Various Conditions
4.1
No of Shop Houses for Each Site
51
4.2
Number of Components for One Shop House
52
4.3
Description of Symbol Used in the Scheduling
54
4.4
Explanation of Symbols in An Example
55
4.5
Assumptions for the Weight of Components
63
4.6
Number of Components per Truck
63
4.7
Time Estimation for 1st Truck (50 km)
70
4.8
Time Estimation for 2nd Truck (50 km)
71
4.9
Time Estimation for 3rd Truck (50 km)
71
4.10
Time Estimation for 4th Truck (50 km)
72
4.11
Time Estimation for 5th Truck (50 km)
72
st
4.12
Time Estimation for 1 Truck (100 km)
97
4.13
Time Estimation for 2nd Truck (100 km)
97
4.14
Time Estimation for 3rd Truck (100 km)
98
4.15
Time Estimation for 4th Truck (100 km)
98
4.16
Time Estimation for 5th Truck (100 km)
98
4.17
Time Estimation for 1st & 2nd Trucks (Case 1:100
111
km)
4.18
Time Estimation for 3rd & 4th Trucks (Case1: 100
112
km)
4.19
Time Estimation for 1st & 2nd Trucks (Case 2: 100
113
km)
4.20
Time Estimation for 1st & 2nd Trucks (Case 1:50 km)
114
xiii
4.21
Time Estimation for 3rd & 4th Trucks (Case 1:50 km)
115
4.22
Time Estimation for 1st & 2nd Trucks (Case 2:50 km)
116
4.23
Time Estimation for 1st & 2nd Trucks (Case 3:50 km)
117
xiv
LIST OF FIGURES
FIGURE NO
TITLE
PAGE
2.1
Flowchart for JIT Deliveries Without Buffer Stocks
20
2.2
Modified JIT Deliveries With 2 Days’ Buffer: Production
21
to Installation
2.3
Critical Path Diagram. Numbers Correspond to Events,
33
and Letters Correspond to Activities and The Time
Taken to Complete the Activity
2.4
Facility Management Overview
35
2.5
Busy Periods, Idle Periods and Interarrival Times
39
2.6
Decomposition of Busy Period Into Sub-busy Periods
39
2.7
Evolution to high-order facility
42
3.1
Research Methodology
46
4.1
Example of Demands Scheduling
55
4.2
Demands at Site 2 (Day 1)
56
4.3
Demands at Site 2 (Day 14)
57
4.4
Demands at Site 2 (Day 25)
58
4.5
Demands at Site 2 (Day 27)
59
4.6
Demands at Site 2 (Day 52)
60
4.7
Demands at Site 2 (Day 69)
61
4.8
Example 1 of Scheduling the Trucks Required
64
4.9
Example 2 of Scheduling the Trucks Required
65
4.10
Example 3 of Scheduling the Trucks Required
66
4.11
Example 4 of Scheduling the Trucks Required
67
4.12
Example 5 of Scheduling the Trucks Required
68
4.13
Example 6 of Scheduling the Trucks Required
69
4.14a
Example 1 of General Scheduling
74
xv
4.14b
Example 1 of Rescheduling
75
4.15a
Example 2 of General Scheduling
76
4.15b
Example 2 of Rescheduling
76
4.16a
Example 3 of General Scheduling
77
4.16b
Example 3 of Rescheduling
78
4.17a
Example 4 of General Scheduling
79
4.17b
Example 4 of Rescheduling
79
4.18a
Example 5 of General Scheduling
80
4.18b
Example 5 of Rescheduling
81
4.19a
Example 6 of General Scheduling
82
4.19b
Example 6 of Rescheduling
82
4.20a
Example 7 of General Scheduling
83
4.20b
Example 7 of Rescheduling
84
4.21a
Example 8 of General Scheduling
85
4.21b
Example 8 of Rescheduling
85
4.22a
Example 9 of General Scheduling
86
4.22b
Example 9 of Rescheduling
87
4.23a
Example 10 of General Scheduling
88
4.23b
Example 10 of Rescheduling
88
4.24a
Example 11 of General Scheduling
89
4.24b
Example 11 of Rescheduling
90
4.25a
Example 12 of General Scheduling
91
4.25b
Example 12 of Rescheduling
91
4.26a
Example 13 of General Scheduling
92
4.26b
Example 13 of Rescheduling
93
4.27a
Example 14 of General Scheduling
94
4.27b
Example 14 of Rescheduling
94
4.28a
Example 15 of General Scheduling
95
4.28b
Example 15 of Rescheduling
96
4.29a
Example 16 of General Scheduling
100
4.29b
Example 16 of Rescheduling a
100
4.29c
Example 16 of Rescheduling b
101
4.30a
Example 17 of General Scheduling
102
xvi
4.30b
Example 17 of Rescheduling
102
4.31a
Example 18 of General Scheduling
103
4.31b
Example 18 of Rescheduling
104
4.32a
Example 19 of General Scheduling
105
4.32b
Example 19 of Rescheduling a
105
4.32c
Example 19 of Rescheduling b
106
4.33a
Example 20 of General Scheduling
107
4.33b
Example 20 of Rescheduling
107
4.34a
Example 21 of General Scheduling
108
4.34b
Example 21 of Rescheduling
109
4.35a
Example 22 of General Scheduling
110
4.35b
Example 22 of Rescheduling
110
xvii
LIST OF SYMBOLS
‫ג‬
-
Intensity coefficient
ρ
-
Probability
t
-
Time
Y
-
Length of the full busy period
G(y)
-
Busy period distribution
∧
G (s ) -
Moment generating function
f(w)
-
Cost of building a road
w
-
Width
F(w)
-
Capacity
D
-
Minimum capacity
N
-
Minimum number of roads
S1
-
Site 1
S2
-
Site 2
S3
-
Site 3
S4
-
Site 4
SB
-
Short beam
LB
-
Long beam
C
-
Column
()
-
Day
xviii
LIST OF APPENDICES
APPENDIX
A
TITLE
Architectural drawings for double
PAGE
125
storey shop houses
B
Key plan for Taman Universiti
132
C
Drawing for double storey shop
133
houses using IBS.
D
General Scheduling
134
E
Rescheduling for 50 km case
138
F
Rescheduling for 100 km case
142
CHAPTER I
INTRODUCTION
1.1
Introduction
The construction industry plays a very vital role in the economic growth
besides providing basic necessity for everyone. Besides, it also provides various
types of job opportunities to the Malaysian. However, due to the advancement in the
science and technology, the construction industry now is very competitive and also
facing the challenges. Besides, according to the concrete association of India (1973),
the use traditional building materials and construction practices has become rather
costly due to one or more of the following reasons such as substantial increase in the
cost of materials, uneconomical structural designs, slow and laborious process of
construction, comparatively shorter life or higher cost of maintenance.
In fact, the construction industry now is unlike the past twenty years ago.
Now, the construction industry put more emphasis on the aspects of time, cost,
quality and safety. It can be said that each construction process is related to the four
aspects as stated earlier. Time is a significant aspect in the construction in which
every project should be completed on time or earlier in order to prevent the
undesirable losses of money. Therefore, the control of time in each construction
process is very important. Other than that, each project now ought to be controlled
within the estimated cost. The quality of the construction product is also a common
issue that be disputed. In this case, quality control is a very important aspect in this
industry. Besides, the construction industry also faces the challenge of safety. For
instance, how to prevent accident and implementing safety regulations at site are the
2
issues that always been emphasis on. Those four aspects are the most challenges that
construction industry has to face today.
In order to achieve those aspects, the construction method used must
progressing. The traditional method of construction that always been adopted in
Malaysia is cast-in-situ method. Although this construction practice has been used
for a long time, however, it is found that this method still has its own weakness.
Hence, a systematic system, which is the industrialized building system (IBS),
should be used in the construction industry in Malaysia in order to supplement the
traditional method.
IBS or precast concrete has been in the use since the latter part of the 19th
century (Joseph J. Waddell, 1974). However, it is seldom been utilized in Malaysia.
According to Fazlur R. Khan (1976), the early use precast construction for structural
members of multi-storey buildings was mostly dictated by the need for quality
control of construction constraints due to extreme bad weather and unusual location
of construction. Industrialization of building or ‘system building’ is a term in the
building industry which indicates the industrialized process by which components of
a building are conceived, planned, fabricated, transported and erected on site (Syed
Mansur Syed Junid, 1986). Generally, by using this system in the construction
industry, a lot advantages can be gained compared to the conventional method.
In this rapid development of science and technology era, the demand of
houses also quite high and sometimes it cannot fulfil the demands. However, by
using the IBS, this problem can directly be solved. It is because with the IBS system,
it can help to reduce the time that normally required building a house. It means that
the total construction time of a building will become shorter by implementing the
IBS.
Other than that, comprehensive prefabricated elements that are produced in
the plant considerably reduce both the amount of work on site. Moreover, it also
reduces the dependence on the weather and the skill of available labour. Therefore it
is no doubt to implement industrialized building system in the construction industry
3
can make the construction faster, economy, and the product of the construction is
more quality. Besides, prefabrication also offered a wealth of architectural shapes
and finishes. In this paper, the industrialized building system and its transportation
used in the shop houses will be discussed.
1.2
Problem Statement
In these few years, the demand for houses and shop houses are quite high. By
using the conventional method, the speed of the construction is quite slow.
Nowadays, a lot of construction cannot be completed on time as required in the
contract document. It can lead losses to the contractors due to the late finish of the
construction.
Other than that, by using the conventional method, the quality in the end of
the construction is not so good. For instance, after removing of formworks, there are
existence of honey comb in the beams and columns. Therefore, industrialized
building systems have been introduced in order to solve those problems.
However, by using industrialized building systems, there also some problems
exist. For instance, the late delivery of the precast components to the site and as a
result, the construction progress is affected. Besides, sometimes the precast
components delivered to the site are not in the right quantity or not in the right types
of precast components. The fabricator has to redeliver the components to the site. It
is waste of time and also money.
In addition, in some cases, the delivery of precast components to the site is
too much early. The space at the site is so limited and therefore causing congestion
of precast components at site. Moreover, there are high probability that the damages
may occur on the precast components if there is no proper storage area for them. All
4
these problems occur are due to the improper management of fabricator who do not
have a detail scheduling on it.
1.3
Objectives
The objectives of this master project are:
• To optimize the number of trucks by scheduling it at specific distance and
quantity.
• To find out the number of trucks that should be controlled in the condition
of break down.
• To introduce a proper management of the delivery of IBS componenet for
fabricator.
1.4
Scope of Study
The scopes of this study are:
•
Emphasis on the study in shop houses on prescribed IBS building
components
•
Sites at Taman Universiti, Skudai, Johor.
•
Do the scheduling for site demands and rescheduling to optimise the
delivery process.
1.5
Significant of the Study
As the construction industry now is facing the challenges of four aspects;
time, cost, quality and safety, it is crucial to have a systematic system or method to
be used in this industry. In this study, an industrialised building system used in the
shop houses will be introduced.
5
Other than that, this study will be a model for the fabricator of the precast
components as a guidelines or ideas in order to know how to manage their trucks in
the delivery to the site. Besides, this study will show the fabricator how to optimise
their schedules in the delivery. The idea of this study of may help the fabricators to
prevent unnecessary problems.
In addition, the progress of construction at site will not be affected due to the
late problem of delivery in terms of types and quantity. It is because proper
scheduling will make the delivery smoothly. Moreover, it is also a way to accomplish
the vision of 2020.
6
CHAPTER II
LITERATURE REVIEW
2.1
Definition of Industrialization
According to Abraham Warszawski (1999), an industrialization process is
defined as an investment in equipment, facilities, and technology with the purpose of
increasing output, saving manual labour and improving quality.
2.2
Characteristics of Industrialization Process
There are six characteristics in order to a successful industrialization. There
are standardization, specialization, centralization of production, mass production,
good organization and integration. For standardization, if the output is standardized,
production resources can be used in the most efficient manner. Besides, the
production process, workers’ training and machinery can be adapted to the particular
characteristics of the product in the best condition.
For specialization, due to the large volume and standardization, it allows a
high degree of labour specialization within the production system. Moreover, the
process can be broken down into a large number of small homogeneous tasks. Hence,
the workers able to work at the high productivity level attained with the
specialization.
7
As for the centralization of production, it means that from the central
location, the product is shipped to the various consumer areas. It is only feasible to
utilize the expensive equipment and facilities if the production is at a single location.
In this case, the process will use the economics of scale with respect to the
management, capital management and also the auxiliary services.
Other than that, a successful industrialization process should have a good
organization. A capable and sophisticated organization is needed in the planning,
coordination and control functions with respect to the production and distribution of
the products. Centralization of production, specialization of work teams and high
volume really need a good organization.
In the aspect of mass production, it is only can justify the investment in
equipment and facilities associated with an industrialization process economically if
only the large production volume considered. It is because such big volume allows a
distribution of the fixed investment charge over a large number of units. Besides, it
will also not to inflate the ultimate cost.
One of the important aspects that must be taken account into is integration. In
a good industrialization process, a very high degree of coordination must exist
between design, production and marketing of the product. Therefore, within an
integrated system, a good coordination between those processes can be obtained as it
is under unified authority.
2.3
Industrialized Building Systems
A building system can be defined as a set of interrelated elements that act
together to enable the designated performance of a building (Abraham Warszawski,
1999). In an industrialized building system, all the buildings elements are
prefabricated offsite, which is in a central facility. Then, the components of the
buildings are sent to the site from the prefabrication yard.
8
Other than that, by using the industrialized building systems, the erection
works at site can be reduced to the minimum. The jointing and finishing work on site
can also be minimising. Besides, the design, production and on site of the buildings
components such as beam, column, wall and so on are strongly interrelated. In this
case, those components must be planned and coordinated accordingly as they are
viewed as parts of an integrated process.
2.3.1
Advantages of Industrialized Building Systems
There are many advantages of implementing industrialized building systems.
One of the advantages is making the construction process faster. It means that the
projects can be completed much earlier than before, which used the conventional
method. Faster completion of works can bring a lot of benefits especially in the
housing projects. The houses can be built within a short time and handover to the
owners. It is quite crucial when the population increase and demands of houses are
quite high. The construction time that be reduced due to that system has an economic
value both to the owner and the contractor.
In addition, there is a big saving in the aspect of labours. According to
Abraham Warszawski (1999), the labour savings in prefabricated elements may
amount to about 80% of their conventional requirement, or to about 40%-60% of the
total labour on site. It is due to the savings of the labours in the masonry, plastering,
painting, carpentry, formwork, tiling and pipe laying (electrical and water supply) at
site. Therefore, it faster for the turnover of working capital and also save in the lifecycle costs of the finished buildings. In fact, the economic value of labour saving due
to the prefabrication depends on the total labour saved in this manner and the
prevailing cost of the labour. Besides, it is also depends on the wage difference
between work done on site and in the plant. The work in plant is usually given lower
wages as it is usually done in the better conditions compared to the works done on
site.
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Compared to the conventional method, which is cast-in-situ, the quality of the
building components prefabricated in the plant is much better. It may due to the strict
and well organised quality control at the prefabrication yard. Moreover, it is much
easier to control the quality at the prefabrication yard than casting at site. The using
of advanced technology of production tools also allow the producing of high quality
products in the batching and casting process. It means that every component is
designed in the view of the particular technology and know how employed by the
plant. In addition, in the large volume of production, it enables more careful choice
of materials and materials suppliers if compared to single construction site.
The prefabricated components of building usually have the longer economic
service life. A higher quality of the components will serve longer before having to be
replaced. Other than that, good quality ensures that less defects such as spots, cracks
or blemishes. There is also lower input of finish works such as screed, plaster, sand
mortar and stucco due to the tighter tolerances in the execution of wall surfaces and
the top and bottom surfaces of floor slabs. Furthermore, it also helps to reduce the
maintenance expenses. It is because prefabricated components require less repair and
preventive maintenance.
2.3.2
Limitations of Industrialized Building Systems
Although there are a lot of advantages of industrialized building systems,
however there are limitations for this system to be used too, for instance, most of the
modules or subjects that be conducted in the universities do not emphasis on the
design of prefabricated building systems, the potential and the problems associated
with the industrialization in building. As a result, the builders and the designers more
tendency to use the conventional method which is familiar to them.
In fact, the industrialized systems are quite rigid with respect to changes that
might be required in the building over its economic life. It is true when the small
span “room size” prefabrication is employed. Besides, in the developed countries, as
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the demand for large public housing projects decrease due to the volatility of the
building market, it is quite risky to use the industrialised building systems if
compared to the conventional labour–intensive method. Moreover, there is abundant
supply of cheap labourers in the most developed country. It makes the limitations use
if industrialised building systems.
Other than that, the weakness of the industrialised building systems is still in
their cumbersome connection and jointing methods. These methods are very
sensitive to the errors and sloppy work. Moreover, for the place where
industrialization is widely used, it will produce more monotonous “barrack-like”
complexes that very often turned into dilapidated slums within several years due to
the excessive tendency toward repetitiveness and standardization in public projects.
Another limitation of the prefabricated systems with respect to the
conventional method is the higher sensitivity of their cost to the various factors.
These factors include distance between the fabrication plant and the construction site,
volume of demand, which is not under the control of the fabricator. The
transportation cost of prefabricated elements form plant to their construction site,
amounts to 3%-5% of their total cost for distances not exceeding 50km-100km
Abraham Warszawski (1999). Hence, prefabrication is at disadvantage when asked
to compete for work at locations far from the fabrication yard. Table 2.1 shows the
relative advantages and disadvantages of industrialization under various conditions.
Table 2.1: Relative advantages and disadvantage of industrialization under various
conditions.
Conditions
Advantage to
Industrialized Conventional
Methods
Method
General market conditions
High volume and stability of demand for buildings
High construction wages
Lack of skilled workers
Centralized planning of building supply
×
×
×
×