Upload
others
View
3
Download
0
Embed Size (px)
Citation preview
The Islamic University – Gaza ــزة ــالمية ـ غ ــة اإلس الجامع
Higher Education Deanship ــا ــات العليـ ــادة الدراسـ عمـ
Civil Engineering كلية الهندسـة ـ هندسـة مدنيـة
Construction Project Management
ــية ــشاريع هندســ إدارة مــ
MODELLING THE FACTORS AFFECTING QUALITY OF BUILDING CONSTRUCTION PROJECTS DURING THE CONSTRUCTION
PHASE IN GAZA STRIP
"Mohammad Issam" Abdel – Aziz M. Amer
Supervised by:
Dr. Rifat Rustum Department of Civil Engineering
A Thesis Submitted in Partial Fulfillment of the Requirements for the Degree of Master of Science in
Construction Engineering and Management
The Islamic University of Gaza – Palestine December, 2002
A
DEDICATION
To those who give of themselves so that others may live.
To my family for their unlimited support.
To my wife for her continuous encouragement.
To my daughters and sons who were missing my direct care during
my study.
To all of my colleagues and friends for their help and support.
B
ACKNOWLEDGEMENT
I wish to express my profound gratitude to Dr. Rifat Rustum for his continued
guidance, supervision, and comments throughout the course of this study. He has
been ever-present force in helping me to mature as a student and as a researcher. His
dedication to helping me succeed is deeply appreciated.
Appreciation is also expressed to Construction Management Teaching Staff at the
Islamic University for their support and encouragement.
I would like to express my special thanks to Mr. Nafez Abu Khater for his assistance
throughout the research.
Finally, I must express my sincere thanks to the Contracting and Consulting firms
for their cooperation and support.
C
ABSTRACT
Quality measurement is the trigger for quality improvement. The things which can
not be measured can not be improved. The real scope of quality improvement in
construction projects is the difficulty and-maybe-lack of quality measurement
methods.
This research is intended to provide clients, project managers, designers, and contractors
with necessary information needed to better manage the quality of a construction building
project in Gaza Strip. Factors that affect the quality of a construction building project during
construction phase are identified. Nominal Group Technique (NGT) was used at the
preliminary stage to identify these factors and the associated sub-factors. Combining the
results of (NGT) and literature review yielded 14 main factors and 60 sub-factors affecting
quality of a building construction project. A questionnaire was developed and used as a
research tool to obtain the opinions of 65 contracting companies and 24 consulting firms on
the identified most important factors affecting quality.
Four Approaches were used throughout the study for the development of
representative models. The appropriate model was resulted from a stepwise multiple
regression analysis on the quality factors resulted from Factor Analysis approach.
It is concluded that the most important factors affecting quality of a building
construction project are: characteristics of site layout, skill and experience of site
staff, characteristics of design documents, and using equipment, materials, quality
and labor management systems and the owner quick response in taking decisions.
Type of awarding system and the political environment also among the factors
effecting quality.
It is recommended that contracting and consulting firms to develop a quality system before
starting the construction of a project to meet the requirements of international quality
standards, and to develop comprehensive management systems for equipment, materials,
and labors. Also, using the developed model as a tool to measure quality of the construction
project and identify the weakness points that lowers the degree of quality and improve it.
D
الخالصة
وكذلك كيفية قياس اجلـودة . تعترب اجلودة من املواضيع ذات األمهية الفائقة يف مشاريع اإلنشاءات يرها لقياس اجلودة نبعت أمهيـة يعترب أحد جماالت حتسني اجلودة، ونتيجة لقلة األدوات اليت مت تطو
.هذه الدراسة من حماولتها إجياد أداة حمددة وواضحة لقياس اجلودة يف مشاريع اإلنشاءات
هدفت هذه الدراسة إلعطاء املالكني ومد راء املشاريع واملصممني واملقاولني املعلومات الـضرورية كذلك حتديـد العوامـل الرئيـسية . لتحسني وإدارة اجلودة يف مشاريع اإلنشاءات يف قطاع غزة
.والفرعية املؤثرة ىف اجلودة خالل مرحلة التشييدميكن عن طريق استخدامها قيـاس جـودة ) منوذج(أيضا هدفت هذه الدراسة لتطوير أداة حمددة
املشروع اإلنشائي وحتديد جماالت الضعف والقصور ومن مث العمل على حتسينها وتطويرها ىف سبيل .لنهائي وهو االرتقاء بصناعة اإلنشاءات يف قطاع غزةحتقيق اهلدف ا
.لقد مت استخدام تقنية اموعات البؤرية املقلصة يف التحديد االبتدائي للعوامل املؤثرة يف اجلودة
١٤باستخدام نتائج ورشة العمل ومراجعة الدراسات السابقة يف املوضوع قيد الدراسة مت حتديـد فرعيا له تأثري مباشر على اجلودة يف مشاريع اإلنشاءات ومن مث استخدام عامال ٦٠عامال رئيسيا و
.هذه النتائج يف تطوير استبيان لقياس مدى أمهية كل عامل من هذه العوامل يف اجلودة . شركة استشارية لتقييم هذه العوامل٢٤ شركة مقاوالت و ٦٥مت دعوة
تها إحصائيا وكذلك مت استخدام اختبـارات مت استخدام برنامج إحصائي إلدخال البيانات ومعاجل إحصائية خمتلفة لدراسة مدى اختالف آراء شركات املقاوالت والشركات االستشارية ىف تقيـيم
.العوامل الرئيسية والفرعية املؤثرة يف اجلودة يف مشاريع اإلنشاءات األوزان املتوسـطية مت استخدام أربعة توجهات لتطوير النموذج املقترح لقياس اجلودة وهى طريقة
.وحتليل باريتو والتحليل العاملى واالحندار اخلطى املتعدد
E
أظهرت الدراسة أنه ليس هناك فروق ذات داللة إحصائية يف توجهات كل من شركات املقاوالت .والشركات االستشارية يف تقييم العوامل املؤثرة يف اجلودة
ئية يف تقييم العوامل املؤثرة يف اجلودة لكل من الشركات كما أنه ليس هناك فروق ذات داللة إحصا .احلائزة على شهادة األيزو وتلك اليت ال متلك هذه الشهادة
مت تطوير أربعة مناذج لقياس اجلودة منها ثالثة مناذج رياضية وأخر منوذج وصفى لتحديـد أكثـر
لرابع الناتج من التحليل العاملى واالحندار وقد مت اختيار النموذج ا. العوامل أمهية يف التأثري يف اجلودة .اخلطى كأفضل النماذج ألنه يتميز بالدقة وسهولة االستخدام
من أهم التوصيات هلذه الدراسة هو استخدام النموذج املقترح لقياس اجلودة وحتديد نقاط الضعف
ة يشمل مجيع أجزاء املؤثرة ىف اجلودة والعمل على حتسينها وكذلك تطبيق نظام أدارى خاص باجلود املشروع اإلنشائي سواء أكان الوثائق التصميمية املعدة للمشروع أم العمليات املستخدمة أثناء تنفيذ
.املشروع مثل إدارة العمال واملواد واملعدات واملوارد املختلفة
F
ABREVIATIONS
QC QM QA TQM GDP PECDAR UNRWA PMBOK ASQC QPMS CII EPC NGT
Quality Control Quality Management Quality Assurance Total Quality Management Gross Domestic Product Palestinian National Council for Development & Reconstruction United Nations Relief and Work Agency Project Management Body of Knowledge American Society for Quality Control Quality Performance Management System Construction Industry Institute Engineer-Procure-Construct Nominal Group Technique
G
TABLE OF CONTENTS
DEDICATION………………………………………………………………. I
ACKNOWLEDGMENT……………………………………………………. II
ABSTRACT…………………………………………………………………. III
ARABIC ABSTRACT……………………………………………………… IV
ABBREVIATIONS…………………………………………………………. VI
TABLE OF CONTENTS…………………………………………………… VII
LIST OF TABLES………………………………………………………….. X
LIST OF FIGURES………………………………………………………… XI CHAPTER 1: INTRODUCTION………………………………………….. 1 1.1 Problem Background………………………………………….………. 2
1.2 Features of Construction Industry in Gaza Strip……………………… 2
1.3 Importance of the Research…………………………………………… 6
1.4 Thesis Objectives……………………………………………………... 6
1.5 Limitations……………………………………………………………. 7
CHAPTER 2: QUALITY DEFINITIONS AND CONCEPTS…………... 8
2.1 Introduction…………………………………………………………… 8
2.2 Definitions…………………………………………………………….. 9
2.3 Concepts………………………………………………………………. 11
2.4 Economics of Quality…………………………………………………. 13
2.4.1 Quality Economics in Design………………………………….. 13
2.4.2 Economics of Quality of Conformance………………………... 14
2.4.3 Cost of Quality…………………………………………………. 15
2.5 Quality Management Philosophies…………………………………… 17
2.6 Total Quality Management…………………………………………… 20
2.7 Quality Management in Construction………………………………… 20
2.8 Factors Affecting Project Quality…………………………………….. 24
2.9 Modeling Concept…………………………………………………….. 31
2.10 Quality Modeling Former Studies……………………………………. 32
H
CHAPTER 3: METHODOLOGY…………………………………………. 36
3.1 Nominal Group Technique……………………………………………. 38
3.2 Defining the Factors Affecting Quality in Gaza Strip………………... 40
3.3 Development of the Research Model…………………………………. 42
3.4 Developing the Questionnaire………………………………………… 44
3.5 Instrument Validity…………………………………………………… 44
3.6 Research Sample……………………………………………………… 45
3.6.1 Sample Size……………………………………………………. 45
3.7 Method of Choosing the Sample……………………………………… 46
3.8 Instrument (Questionnaire) Reliability……………………………….. 47
3.9 Method of Collecting Data……………………………………………. 47
3.10 Method of Data Analysis……………………………………………... 47
3.11 Model Verification……………………………………………………. 48
CHAPTER 4: DATA PRESENTATION AND ANALYSIS……………... 49
4.1 The Descriptive Method………………………………………………. 49
4.1.1 Section 1: Company Profile……………………………………. 49
4.1.2 Section 2: Quality in the Organization………………………… 54
4.1.3 Section 3: Main Factors Affecting Quality of Construction Projects. 56
4.1.4 Section 4: Sub-factors Affecting Quality of Construction Projects… 57
4.2 Inferential Statistics…………………………………………………… 60
4.2.1 T-test…………………………………………………………… 60
4.2.2 The Spearman (rho) correlation coefficient test……………….. 62
4.2.3 One-Way ANOVA test………………………………………… 65
I
CHAPTER 5: MODEL DEVELOPMENT……………………………… 68
5.1 Approach 1: The Weighted Average Approach………………………. 69
5.1.1 Model Formulation…………………………………………….. 70
5.2 Approach 2: Pareto Analysis of Main Factors Affecting Quality……. 71
5.3 Approach 3: Factor Analysis of Sub-factors Affecting Quality……… 74
5.3.1 Factor Extraction………………………………………………. 74
5.3.2 Factor Rotation………………………………………………… 78
5.4 Approach 4: Stepwise Multiple Regression Analysis………………… 83
5.5 Choosing the Appropriate Model……………………………………... 87
5.6 Model Application……………………………………………………. 87
5.7 Model Verification……………………………………………………. 91
CHAPTER 6: CONCLUSION AND RECOMMENDATION…………… 95
6.1 Conclusion……………………………………………………………. 95
6.2 Recommendation……………………………………………………... 97
REFERENCES……………………………………………………………… 99
APPENDICES
APPENDIX A………………………………………………………... 102
APPENDIX B………………………………………………………... 108
APPENDIX C………………………………………………………... 119
APPENDIX D………………………………………………………... 120
APPENDIX E………………………………………………………… 122
APPENDIX F………………………………………………………… 123
J
LIST OF TABLES
Table 1.1 Cost of Construction of Buildings by cost item and region……. 3
Table 1.2 Cost of Buildings during 1999 in Palestinian Territory………... 4
Table 1.3 Main Economic Indicators for Construction Activities………… 4
Table 1.4 Development of Issued Buildings Licenses (1996-2000)………. 5
Table 2.1 Quality Cost Elements………………………………………….. 17
Table 2.2 Impacting Factors Affecting Quality…………………………… 28
Table 3.1 Participants attended NGT session……………………………... 38
Table 3.2 Factors Affecting Quality of the Construction Building Project.. 40
Table 3.3 Classification of Sample Size of Contracting Companies……… 46
Table 3.4 Number of the Questionnaire Respondents…………………….. 47
Table 4.1 Establishment Year of Companies……………………………... 50
Table 4.2 Classification of Contracting Companies………………………. 51
Table 4.3 Number of Company Staff……………………………………... 52
Table 4.4 The Companies developed a clear definition of Quality………. 54
Table 4.5 Percentage of employees concerned of quality………………… 54
Table 4.6 Implementation of Quality System…………………………….. 55
Table 4.7 Top Management Support for Quality...………………………... 55
Table 4.8 Scores of the Main Factor Affecting Quality…………………... 56
Table 4.9 Scores of the Sub-factors Affecting Quality…………………… 57
Table 4.10 Average Scores of Main Factors resulted from ranking Sub-factors… 59
Table 4.11 T-test results……………………………………………………. 61
Table 4.12 Spearman test results…………………………………………… 63
Table 4.13 Critical Values of (rho) at Various Levels of Probability……… 64
Table 4.14 One-Way ANOVA results……………………………………… 66
Table 5.1 Average Weight of Main Factors ……………………………… 69
Table 5.2 Pareto Analysis of Quality Factors……………………………... 71
Table 5.3 Initial Statistics for the 60 Variables…………………………… 75
Table 5.4 Factor Rotation Results………………………………………… 79
Table 5.5 New Factors Affecting Quality………………………………… 81
Table 5.6 Stepwise Multiple Regression Analysis Results……………….. 84
K
LIST OF FIGURES
Fig. 2.1 Design Quality Economics………………………………………. 14
Fig. 2.2 Economics of Quality of Conformance………………………….. 15
Fig. 2.3 Process Control…………………………………………………... 23
Fig. 2.4 The Proposed Concept of the Construction Process……………... 28
Fig. 2.5 Quality Measurement Matrix…………………………………….. 33
Fig. 2.6 Flowchart of Blueprint Process…………………………………... 34
Fig. 3.1 Research Methodology…………………………………………... 37
Fig. 3.2 The Research Model……………………………………………... 43
Fig. 4.1 Type of Organization…………………………………………….. 49
Fig. 4.2 Position of Respondent…………………………………………... 51
Fig. 4.3 Type of Projects the companies are dealing with……………….. 52
Fig. 4.4 Number of Projects executed in the last five years………………. 53
Fig. 4.5 The Value of Projects executed in the last five years……………. 53
Fig. 5.1 Quality Factors, Voting and Scoring Results…………………….. 72
Fig. 5.2 Pareto Analysis of Quality Factors………………………………. 72
Fig. 5.3 Factor Scree Plot…………………………………………………. 78
Fig. 5.4 Model 3………………………………………………………….. 82
Fig. 5.5 Form 1: Worksheet for Measuring Quality in Construction Projects…. 89
Fig. 5.6 Form 2: Excel Worksheet for Measuring Quality in Construction …… 90
Fig. 5.7 Excel Worksheet for Khanyounis Preparatory girls school……………. 92
Fig. 5.8 Excel Worksheet for Farabi Elementary boys school………………….. 94
١
CHAPTER 1 INTRODUCTION
Quality has become a very popular subject in recent years due to conceptual changes
in the industry. The definition of quality in the past as “compliance to standards” is
now found to be inadequate and replaced with the current definition as “customer
satisfaction” (Abdel-Razek, et al., 2001).
The approach to quality has evolved from control (QC) to management (QM)
through assurance (QA) and reached policies like Total Quality Management
(TQM). In developed countries, where quality systems have been established long
time ago, the principle has become to produce quality rather than to control it at the
end. The new approaches are not only beneficial to the customer but also to the
manufacturer as cost of quality is optimized to minimize the total loss. The results
are less cost per unit of better quality, more share in the market and increased profits
(Davis, et al., 1989).
In construction industry, the quality is generally considered to be very costly, and
QC or QC/QA organizations are established only as a result of contractual
requirements. In construction industry, production is different from factory or plant
production, therefore quality considerations need special care. Especially when the
production (construction/installation) is not in place, cost of remedial works may go
extremely high if attention is not paid to quality assurance (Barrett, 2000).
In the modern construction market, quality is a major function in construction
organization. Quality is rapidly becoming as important factor as price has been
traditionally (Davis, et al., 1989).
٢
1.1 Problem Background
Like the majority of developing economics, Gaza Strip has been relying completely
on the philosophies, methods and techniques concerning quality that were initiated
and developed in both the West and the Far East. These have been accepted and ill-
applied without any adaptation to suit the backgrounds of the countries. Efforts to
improve quality in developing countries should be based on methods that stem from
their own economic and technological backgrounds. The characteristics of these
backgrounds should be turned into advantages to give a competitive edge instead of
being regarded as constraints and limitations on the application of the methods and
techniques expounded in the modern imported philosophies on qualit (Abdel-Razek, 1998a).
The construction industry in Gaza Strip is characterized by poor quality. There is no
current published work which addresses any of these aspects of quality in a way that
relates to, or is adapted to suit, the economic, political, social and technological
environment of Gaza Strip. Nor is there any published work, which is written from
the standpoint of Gaza Strip human resources, and the structure of its construction
industry and organization. Therefore, determining the construction industry’s
viewpoint on the factors which would improve construction quality in Gaza Strip,
and the relative importance of each factor, is an essential first step towards
establishing methods for a real improvement of construction quality in Gaza Strip
and most other developing countries.
1.2 Features of Construction Industry in Gaza Strip
The construction industry is considered to be an engine in the national economy. It
is a large, mature business and it has many important links to the rest of the
economy. The importance of the construction industry to the economy can be
measured by its contribution to the GDP; its contribution to investment, and the
amount of manpower employed. Internationally, the construction industry
contribution to the GDP is about 3-10%, less in developing countries than in the
developed ones. In developing countries it usually accounts for between 3 percent
and 8 percent of the GDP. It constitutes 50-60% of gross fixed capital formation in
majority of countries. The World Bank suggested a growing recognition that
٣
construction can be a more important generator of jobs in developing countries
(Trigunarsyah, 2002).
The large numbers of participants, the complexity of the relationships and the large
number of functions to be performed means the construction process does not
always work smoothly. It is often cumbersome and inefficient.
The construction industry in Gaza Strip is considered to be one of the main
industries. It has grown significantly since the birth of Palestinian National
Authority in 1994. The following Tables (1.1, 1.2, 1.3, and 1.4) indicate the
characteristics of construction industry in the Palestinian Territory as reported by the
Palestinian Central Bureau of Statistics (PCBS, 2000).
Table 1.1: Cost of Construction of Buildings in Palestinian Territory by Cost Item
and Region during the year of 1999. (Value in US $ 1000) (PCBS, 2000)
Cost Item Gaza Strip West Bank
Excavation by Machinery
Workmanship
Construction Materials *
Workmanship +Materials **
Contracting Companies
Licensing Fees
Utilities Construction Fees
Others
Total
980.2
41794.6
117500.2
60080.8
23339.4
2242.2
2723.1
1438.8
250099.3
12011.6
132578.0
453381.2
93280.5
20647.5
6617.2
6174.3
2277.9
726968.2
* Construction materials purchased by Owners
** Includes workmanship and materials
٤
Table 1.2: Cost of Construction of Buildings during 1999 in Palestinian Territory
(Values in Million US $) (PCBS, 2000)
Item Value
Cost of building construction by building type:
Building
Villa / House
Establishment
Others, including marginal buildings and
enclosures
211.3
463.8
43.4
281.5
Cost of building construction by building status:
completed
Under construction
Under construction and utilized but not
completed
405.3
445.2
249.5
Cost of building construction by building
utilization:
Residential only
Work only
Work and Residential
Others
499.5
49.8
104.7
346.0
Table 1.3: Main Economic Indicators for Construction Contractors Activities
Formal Sector, (1996-1999) (Values in US $1000) (PCBS, 2000)
Year Indicator
1996 1997 1998 1999
No. of Enterprises
No. of persons engaged
Compensation of employees
Output
Intermediate consumption
Value adds
447
5169
24,910.2
196,658.9
120,371.2
76,287.6
488
5538
27,987.2
216,738.0
136,364.2
80,373.9
408
5911
30,426.7
225,663.1
123,874.0
101,789.2
337
4153
27,005.0
199,326.5
99,540.0
99,786.0
٥
Table 1.4: Development of Issued Building Licenses, (1996-2000) (PCBS, 2000) Licensed Area (1000
m2) Number of Licenses Period
Existing
Areas New
Areas Existing
Extensions
Existing
Buildings
Additions+
Existing
Parts
Additions to
Licensed
Buildings
New
Buildings
1996
Quarter I
Quarter II
Quarter III
Quarter IV
Total
48.8
100.6
44.9
108.1
302.3
391.1
493.6
691.2
714.2
2290.1
39
33
16
36
124
116
248
116
329
809
26
11
24
14
75
429
467
584
582
2062
852
863
1452
1373
4540
1997
Quarter I
Quarter II
Quarter III
Quarter IV
Total
114.0
111.3
150.9
123.9
500.1
600.7
624.6
592.4
574.2
2391.8
50
40
111
62
263
231
254
358
312
1155
26
43
50
68
187
491
527
453
523
1994
1139
1172
1280
1198
4789
1998
Quarter I
Quarter II
Quarter III
Quarter IV
Total
120.5
121.6
121.3
102.7
469.1
569.3
535.2
743.6
657.6
2505.7
55
47
46
30
178
265
264
297
318
1144
39
65
71
90
265
460
468
715
609
2252
1055
1246
1488
1328
5117
1999
Quarter I
Quarter II
Quarter III
Quarter IV
Total
135.7
147.9
145.0
125.8
554.4
554.0
778.2
827.5
700.4
2860.1
38
10
43
24
115
349
365
357
399
1470
87
126
139
123
475
446
597
478
534
2055
1105
1593
1771
1334
5803
2000
Quarter I
Quarter II
Quarter III
Quarter IV
Total
110.1
138.3
163.4
70.6
482.4
551.7
602.3
806.0
497.6
2457.6
35
57
57
36
185
340
346
415
217
1318
79
140
163
66
448
424
520
590
318
1852
1044
1312
1523
619
4498
٦
Construction projects are constructed by either public organizations (PECDAR,
UNRWA, Ministry of Housing, Ministry of Education, etc.), or the private sector.
Most public work projects are awarded in a competitive bid. Professional designers
and constructors are engaged in separate contracts. The contractors usually would
not be involved until the designs have been completed. The private sector is usually
following the same approach in executing its construction projects.
1.3 Importance of the Research
• Quality is playing a pivot role during the construction phase of the
project.
• There is a need to develop a specified method to measure quality due to
lack of quality measurement methods.
• It is noticed that there are a number of problems in the construction
industry caused by bad quality control, and the situation seems to getting worse.
Projects are frequently late, over budget and suffer from poor workmanship and
materials. Conflict is increasing, resulting in litigation and arbitration with
depressing regularity.
• Failure of many contracting firms happened due to these problems.
• Understand the quality criteria for the building construction projects and
its impacting factors will make it possible to handle the quality problems much
better.
1.4 Thesis Objectives
1. Define the factors that affect the quality of the building construction projects
during construction phase which serves as the basis and reference point for
implementing quality model and quality improvement.
2. Derive the relative weights of the impacting factors to provide a base to
develop a model for measuring quality.
3. Define a model(s) to represent the factors affecting the overall quality of
construction building projects.
٧
4. Testing the hypothesis that there is a significant difference in perception
between contracting and consulting companies with regard to factors affecting
quality.
5. Testing the hypothesis that there is a significant difference in ranking quality
factors between contracting companies who have an ISO certificate and those
who do not have.
6. Testing the hypothesis that there is a significant difference in ranking quality
factors due to the position of respondent (Manager, Deputy Manager, Project
Engineer and Site Engineer).
1.5 Limitations
This thesis is restricted by the following items:
1. Due to time limitation, this research is concerned with construction building
projects only (housing, schools, hospitals, etc.), and will not take into account
the other categories of engineering projects like civil projects (tunnels,
highways, bridges), or industrial projects (factories and workshops), and utilities
projects (sewage and water supply).
2. Most of projects in Gaza Strip are awarded in a competitive bid. Owners
usually hire consultants. As those consultants represent the viewpoint of owners,
this research will take into consideration the opinions of two categories,
contractors and consultants.
3. Only the contractors registered in the Palestinian Contractors Union and the
consultants who are registered in the Engineering Association will be involved
in this study.
4. This research will focus on evaluating the factors affecting quality of the
construction building projects during the construction phase. This phase is an
important and more representative phase, because all parties and resources are
involved in it. Also, the construction phase is an intermediate phase; outputs of
pre-construction affect quality in construction and outputs of construction affect
quality in post-construction. Therefore, measuring quality in the construction
phase is very effective and representative of the construction building project
quality.
٨
CHAPTER 2
QUALITY DEFINITIONS AND CONCEPTS
2.1 Introduction
Egyptian wall paintings from around 1450 B.C. show evidence of inspection and
measurement activity. Stones in the pyramids were cut so precisely that it is
impossible to put a knife blade between the rocks. The Egyptian’s success was due
uniformed methods and procedures and precise measuring devices. The Egyptians
also entertained the idea of interchangeable bows and arrows. Since variation in
materials, craftspeople and tools existed, some method of quality control was
necessary. During the Middle Ages in Europe, the skilled craftsperson served both
as manufacture and inspector. Since the manufacturer dealt directly with the
customer, considerable pride in workmanship existed. Craft guides, consisting of
masters, journeymen, and apprentices, emerged to ensure that craftspeople were
adequately trained. Every effort was made to ensure that quality was built into the
final product (Willis, 1996).
Following the World War II, two major forces emerged that have a profound impact
on quality. The first force was the Japanese revolution in quality. Prior to World
War II, many Japanese products were perceived, throughout the world, to be in
quality. To help selling their products in international markets, these are some of
Japanese revolutionary steps to improve quality:
1. The upper managers personally took charge of leading the revolution.
2. All levels and functions received training in quality disciplines.
3. Quality improvement projects were undertaken on a continuous basis.
The second major force was the prominence of the product quality in public mind.
Several trends converged to highlight this prominence: product liability cases, concern about the environment, pressure by consumer organizations, and the
٩
awareness of the role of quality in trade, weapons and other areas of international
competition. These two major forces have resulted in quality, become a cardinal
priority for most organizations (Juran and Gryna, 1999).
2.2 Definitions
Definitions of quality are abounding. For many years there have been attempts to
define the meaning of quality, often in general terms, yet more recently in terms of
the formulation of quality through “quality assurance systems”. Some definitions
result from authoritative documentation, while others express experiences, opinions,
and conjecture. Although considerable disparity prevails, there is also much
common ground in the various definitions.
The British Standard Institution defines quality as “the totality of features and
characteristics of a product or service that bear on its ability to satisfy stated and
applied needs” (McCabe, 1998). This definition implies that there is a need to
identify the features and characteristics of products and services that relate to quality
and form the basis for measurement and control. The “ability to satisfy applied
needs” reflects the value of the product or service to customer, including the
economic value as well as safety, reliability and maintability.
A second, product-based definition is that quality is a precise and measurable
variable and that differences in quality reflect differences in quantity of some
product attribute. This definition mistakenly relates the quality to cost: the higher the
cost, the higher the quality. However, a product-term used to refer either to
manufactured good or a service- need not to be expensive to be considered as a
quality one (Evans & Lindsay, 1992).
A third definition is based on the assumption that quality is determined by what a
customer wants and what he is willing to pay for. Individuals have different wants
and needs and hence different quality standards. This leads to a user-based definition
stated by Juran (El-Sawah, 1998) “ Fitness for purpose/use” and adopted and
described in ISO 8402 as “That which relates to the evaluation of a product or
service to its ability to satisfy a given need” (El-Sawah, 1998). The “fitness for use”
١٠
definition is driven by customer satisfaction, and has become the principal definition
of quality in the manufacturing and service industries.
To unfold the definition, the meaning of “customer” should be understood. A
customer is anyone who is impacted by the product or the process and can be
considered as external and internal customer. External customers include not only
the ultimate users but also immediate processors, as well as merchants. For
construction, the product is the completed facility, and the external customer is the
final user of the facility. Internal customers include all functions impacted by the
product at both the managerial and work levels. The internal customers receive
products and information from the groups of individuals within their organization.
Satisfying the needs of these internal customers is an essential part of the process
supplying the final external customer with a quality product. For example, for a
carpenter preparing formwork, the final customer may be the owner, but the internal
customer is the crew that will use the forms when placing the concrete. This is the
customer that the carpenter must seek to satisfy determining the placing crew’s
needs and expectations with regard to forms (Juran and Gryna, 1999)
A fourth definition of quality is manufacturing-based definition: Quality is an
outcome of engineering and manufacturing process. Crospy has stated that Quality is
“ A conformance to agreed and fully understood requirements”. Crospy believes that
quality is not comparative, and there is no such thing as high quality or low quality.
A product or service either conforms to requirements or it does not (McCabe, 1998).
The fifth definition, a value-based definition states that quality is defined in terms of
costs and prices, “Uniformity of the product characteristics or delivery of a service
around a nominal or target value”. This definition is concerned with locating the
product characteristics and process parameters within the design specifications or
limits (El-Sawah, 1998).
١١
There is a need for different definitions: perspectives change at different points in an
organization. Reliance on a single definition is frequently a source of problems. One
needs to shift perspective of quality as products move from design to market.
All views are necessary and must be embodied in an overall company philosophy in
order to result in a quality product. The diversity of these definitions may be
explained by examining eight principal quality dimensions: (Evans and Lindsay,
1992).
1. Performance: a product’s primary operating characteristics.
2. Features: the properties of a product.
3. Reliability: the probability of a product’s surviving over a specified period of time
under stated conditions of use.
4.Conformance: the degree to which physical and performance characteristics of a
product match pre-established standards.
5. Durability: the amount of use one gets from a product before it physically
deteriorates or until replacement is preferable.
6. Serviceability: the speed, courtesy, and competence or repair.
7. Aesthetics: how a product looks, feeds, sounds, tastes or smells.
8. Perceived quality: subjective assessment resulting from image, advertising or
brand names.
Because each of the basic definitions focuses on different quality dimensions,
conflicts are inevitable. The most applicable definitions are fitness for use (the
design perspective) and conformance to specifications (the manufacturing
perspective).
2.3 Concepts
Quality policy: is the overall intentions and directions of an organization as regards
to quality, as formally expressed by top management (McCabe, 1998).
Quality management: is the umbrella term for approaches to quality. The definition
of quality management according to BS, EN, ISO 8402 is “All activities of the
١٢
overall management function that determine the quality policy, objectives and
responsibilities, and implement them by means such as quality planning, quality
control, quality assurance and quality improvement within the quality system
(McCabe, 1998).
Project Management Body of Knowledge (PMBOK), is a guide to the project
management, states that project quality management is a subset of project
management that includes the process required to ensure that the project will satisfy
the needs for which it was undertaken. It consists of quality planning, quality
assurance and quality control (Project Management Institute, 2000).
Quality control according to BS, EN, ISO 8402 is “the operational techniques and
activities that are used to fulfil requirements for quality” (McCabe, 1998).
Quality System is defined in BS, EN, ISO 8402 as “ Organizational structures,
procedures, processes and resources for implementing quality management”
(McCabe, 1998).
A comprehensive quality system according to (Harris and McCaffer, 1995) in the
context of construction does not depend simply on inspection and control, but on a
whole system that will include:
1. Current instructions to all, clearly communicated.
2. Appropriate abilities and skills, hence training.
3. Suitable, safe and effective equipment.
4. Good site working conditions, with proper inspection.
5. Checks or tests on completed work, properly recorded.
6. The power ad authority to correct faults.
7. Motivation to produce quality.
8. A document system that records pass/fail.
9. Confirmation that faults have been remedied.
Quality Assurance: is defined according to BS, EN, ISO 8402 as “all the planned
activities implemented within the quality system, and demonstrated as needed, to
١٣
provide adequate confidence that an entity will fulfil requirements for quality”
(McCabe, 1998).
Thus quality management embraces all the actions an organization takes to achieve
its quality policy. Some of these actions may unpremeditated and unsystematic, but
most will follow organized routines established in advance. They form the quality
system. Such a system must necessarily be made up of a number of elements and
those elements are identified and described in quality system standards. Some of
these elements will provide quality control by eliminating non-conformance. Others
will supply verifications, or assurance to management, to the customer, to regulatory
authorities, or to all three.
2.4 Economics of Quality
The economics of quality must be considered in both design and construction.
2.4.1 Quality economics in design
In the simplest form Figure 2.1 below illustrates the relationship between the cost
and value of quality in design. The horizontal axis relates to the quality of design as
reflected by the quality characteristics chosen for the item concerned. The vertical
axis shows that both the cost and value of quality. The value curve is concave
downward. As quality increases, the value increases, but at a decreasing rate. In
other words the value of the additional unit of quality becomes less (Barrie and
Paulson, 1992).
On the other hand, the cost curve shows that as quality of design increases, the
marginal cost of each additional unit of quality increases more with each step. The
last increment of quality costs for more than the first, until it becomes too costly to
specify higher standards. In concept, the optimum level of quality occurs at the level
where the marginal cost of one additional unit equals the marginal value. In the
figure, this occurs where the slopes of the two curves are equal (Barrie and Paulson,
1992).
١٤
Figure 2.1: Design Quality Economics (Barrie & Paulson, 1992)
2.4.2 Economics of quality of conformance
The cost of quality control may be classified in two groups (Barrie & Paulson,
1992):
1. The cost of the skilled labor, equipment, materials, methods and supervision
to produce quality output.
2. The costs of monitoring and verifying the quality output and correcting or
replacing defective work.
To achieve increasing quality of conformance directly from the resources and
methods, more money should be invested in them, and hence direct cost goes up. On
the other hand, as the reliability of the methods and resources improves, less
investment is required for monitoring their performance and for correcting and
replacing defective work, so the cost of quality control goes down. To optimize
conformance costs, the sum of the direct construction costs and the quality control
١٥
costs should be minimized (Barrie & Paulson, 1992). Figure 2.2 illustrates the trade-
off between these two categories of costs
Figure 2.2: Economics of Quality of Conformance (Barrie & Paulson, 1992)
2.4.3 Cost of Quality
Traditionally, the reporting of quality related costs had been limited to inspection
and testing; other costs were accumulated in the overhead accounts. As the full-
range of quality-related costs began to be defined, a number of facts emerged:
1. Quality related costs are much larger than had been traditionally reported,
generally in the range of 20 to 40% of revenues.
2. Quality related costs are not only related to manufacturing operations, but to
ancillary services such as purchasing and customer service departments as well.
3. Most of the costs are result of poor quality and are avoidable.
١٦
The American Society for Quality Control (ASQC) divides quality costs into four
separate categories (Evans and Lindsay, 1992):
1. Prevention costs: costs incurred to prevent the occurrence of nonconformance in
future.
2. Appraisal costs: costs incurred in measuring and controlling current
production to assure conformance to requirements.
3. Internal failure costs: costs generated before a product is shipped as a result
of nonconformance to requirements.
4. External failure costs: costs generated after a product is shipped as a result of
nonconformance to requirements
These cost categories allow the use of quality cost data for a variety of purposes.
Quality costs can be used for measuring progress, analyzing problems, or budgeting.
By analyzing the relative size of the cost categories, the company can determine if
its resources are properly allocated.
Quality costs are an important means for directing management action. They also
can help management track the success of its quality improvement efforts. Ideally,
the total cost of quality will decline over time. Crosby recommends a 10 percent per
year goal for reducing total cost of quality (Pyzdek and Berger, 1996).
The key to improving quality and profitability is prevention. A fundamental
approach of total quality assurance is that an increase in prevention expenditures
will generate larger savings in all other cost categories. Better prevention of poor
quality will clearly reduce internal failure costs, since fewer defective items will be
made. External failure costs will also be reduced. In addition, fewer appraisals will
be required, since the products will be made correctly the first time. Table 2.1 below
provides a guide to some of the more commonly encountered quality cost elements
(Pyzdek and Berger, 1996).
١٧
Table 2.1: Quality Cost Elements (Pyzdek and Berger, 1996).
Category Elements
Prevention Costs
Quality planning
Process control planning
Design review
Quality training
Gage design
Appraisal Costs
Receiving inspection
Laboratory acceptance testing
In-process inspection
Quality audits
Calibration
Internal Failure Costs
Rework
Scrap
Process troubleshooting
Material review and activity
Re-inspection or retest
External Failure Costs
Processing of customer complaints
Unplanned field repair
Recalls
Processing of returned material
Warranty
2.5 Quality Management Philosophies
Three philosophers W.Edwards Deming, Joseph Juran and Philip Crospy, have
emerged as major international philosophers in the quality revolution. They have
developed distinct philosophies on how to measure, manage and improve quality.
Deming (McCabe, 1998) focuses on the improvement of product and service
conformance to specifications by reducing uncertainty and variability in the design
١٨
and manufacturing process. In Deming’s view, variation is the chief culprit of poor
quality. To achieve reduction of variation, he advocates a never-ending cycle of
product design, manufacture, test, and sales, followed by market surveys, the
redesign, and so forth. Deming claims that higher quality leads to higher
productivity, which in turn leads to long term competitive strength.
Deming (McCabe, 1998) identifies two sources of improvement in any process:
reducing the “common causes” of variation inherent in the production system, and
eliminating isolated “special causes” identifiable with a specific individual, machine,
or batch of materials. Statistical methods provide a means for identifying special
causes and understanding common causes.
Statistical thinking is only a portion of the modern Deming philosophy. Deming
emphatically states that managerial practices are in need of a radical overhaul. His
“14 points” constitutes the core of his program for achieving quality excellence and
is listed below. The Deming philosophy is an all-or-nothing proposition; none of the
14 points cannot be viewed in isolation, and companies can not be selective in the
ones they wish to implement.
1. Create constancy of purpose towards improvement of product and service,
with the aim to become competitive, stay in business and provide jobs.
2. Adopt the new philosophy, top management and everybody.
3. Cease dependence on inspection to achieve quality.
4. End the practice of awarding business on the basis of price tag.
5. Improve constantly and forever the system of production and service.
6. Institute training on the job.
7. Teach and institute leadership.
8. Drive out fear. Create trust. Create a climate for innovation.
9. Break down barriers between departments.
10. Eliminate slogans, exhortations and targets for the workforce.
11. Eliminate work standards (quotas).
12. Remove barriers that rob people of pride of workmanship.
13. Encourage education and self-improvement for everyone.
14. Take action to accomplish transformation.
١٩
Juran (McCabe, 1998) defines quality as “fitness for use”. This is broken down into
four categories: quality of design, quality of conformance, availability and field
service. Quality of design focuses on market research, the product concept and
design specifications. Quality of conformance includes technology, manpower, and
management. Availability focuses on reliability, maintability, and logistical support.
Field service quality comprises promptness, competence, and integrity.
Juran provides ten essential stages explaining his perspective:
1. Create awareness of the need and opportunity for quality improvement.
2. Set goals for continuous improvement.
3. Build on organization to achieve goals by establishing a quality council,
identifying problems, selecting a project.
4. Give everyone training.
5. Carry out projects to solve problems.
6. Report progress.
7. Show recognition.
8. Communicate results.
9. Keep a record of successes.
10. Incorporate annual improvements into the company’s regular systems and
processes, and thereby maintain momentum.
The essence of Crosby’s quality philosophy is embodied in what he calls the
“Absolutes of Quality Management” and the “Basic Element of Improvement”.
Crosby’s approach is summarized in the following points for quality management
(McCabe, 1998):
1. Quality means conformance to requirements, not elegance.
2. There is no such thing as a quality problem; problems must be identified by
those individuals or departments that cause them.
3. There is no such thing as the economics of quality; it is always cheaper to do
the job right the first time.
4. The only performance measurement is the cost of quality.
5. The only performance standard is “Zero Defects”.
٢٠
2.6 Total Quality Management
Total quality management (TQM) is an integration concept for continuously
improving the quality of goods and services delivered through the participation of all
levels and functions of the organization. TQM is simply the process of building
quality into goods and services from the beginning, and making quality everyone’s
concern and responsibility. The success of TQM depends on the genuine
commitment to quality of every member of the organization. ( Evans and Lindsay,
1992)
Successful TQM program should have the following attributes (Olomolaiya and
Jayawardane, 1998):
1. Committed leadership of the highest standard throughout the life time of the
organization.
2. Training targeted to every level of management and employees.
3. Teamwork, which means that everyone participate in the improvement
efforts.
4. Upstream prevention management which requires seeking out potential
problems
and not merely waiting for a failure to happen before effecting improvement.
5. Ongoing prevention action requiring the need to attack constantly the real
root causes of problems.
6. Improved communication to make sure that all required information is
supplied at the correct level, at the correct time and to the required degree of
detail.
7. Clearly identified vision, mission and goals: TQM cannot be steered to
continuous improvement without them.
8. Focus on employees to include carrier development plans, profit sharing,
enhancing training, employee involvement and recognition; employee
satisfaction is indispensable in TQM.
2.7 Quality Management in Construction
٢١
The construction industry is typified by highly differentiated, fragmented and
loosely structured system. The skills, loyalty and orientation of professionals and
practitioners in the industry have developed in an environment of specialization,
differing traditions and often opposing interests at integration, if any, are presently
weak. Developing a quality system is the first step towards improving quality in
construction industry.
A quality system consists of the following (Nee, 1996):
• Quality policy
• Organization structure
• Procedures
• Processes
• Training
• Quality manual
Quality Policy (Nee, 1996)
The quality policy shall be relevant to the organization’s goals and the expectations
and needs of its customers. The quality policy must state goals and objectives that
are measurable and pertinent to the organization’s functional plan and the
expectations and needs of its customers. The documented quality system should be
designed to carry out goals and objectives of the quality policy.
Organization for Quality (Nee, 1996)
The first objective in establishing a quality system should be to satisfy the internal
needs of the organization. It follows therefore that it should be cost-effective,
compatible with accepted good practice within the industry concerned, and
beneficial to the organization. There are two types of systems for implementation of
quality: centralized and decentralized systems.
• Centralized Systems
Centralized systems lay stress on the practice of quality control or the operational
techniques and activities that are used to fulfil requirements for quality. Under a
centralized system, the quality related operations would be the responsibility of a
٢٢
quality control department with its own management hierarchy independent of
production departments (Ashford, 1989).
• De-centralized System
The difference between centralized and de-centralized systems is that in the latter
the responsibility for controlling quality is placed firmly on the shoulders of those
actually doing the work. This follows the principle that production management has
a duty to make things comply with specifications, a duty which should not be
permitted to relinquish or to share with others (Ashford, 1989).
Quality System Procedures
The quality system through the documented procedures must be effectively
implemented. The complexity of the procedures depends on the complexity of work,
methods used, skills, and training needed in carrying out the activity. Documented
operational procedures should be developed to coordinate different activities with
respect to an effective quality system. All documented procedures should be stated
simply, understandable, unambiguously, and should indicate methods used and
criteria to be satisfied (Nee, 1996).
Process Control
The organization shall identify and plan production (construction), installation, and
servicing processes directly affecting quality. It shall insure that all of these processes
are carried out under controlled conditions including the following (Nee, 1996):
• Use of appropriate equipment for the construction, installation, or
servicing, and a suitable working environment.
• Compliance with all applicable codes, quality plans and documented
procedures.
• Monitoring and controlling process parameters and product
characteristics.
• Approval of process and equipment as required.
٢٣
• Criteria for workmanship defined in the clearest practical manner-e.g.,
written standards, representative sample, or illustrations.
• Suitable maintenance of equipment to ensure continues process capability.
Figure 2.3 provides a simple step-by step approach to each process being
undertaken (Nee, 1996).
Figure 2.3: Process Control (Nee, 1996)
Training
The organization shall establish and maintain documented procedures for identifying
the training needs of all personnel performing activities affecting quality. The
required training shall be provided and, where personnel are performing specific
assigned tasks, they shall be qualified on the basis of appropriate education. Records
of all training shall be maintained (Nee, 1996).
Quality Manuals
The purpose of the quality manual is to provide an adequate description of the
quality management system which is serving as a permanent reference in the
implementation and maintenance of that system. To the extent that each company is
٢٤
unique, it follows that every company’s quality manual should be an original
document. The manuals could be in five sections, which are discussed below (Evans
and Lindsay, 1992):
1. Control
This section introduces the manual to the reader, establishes its authority and
describes the method adopted to keep the manual up-to –date and to inform users of
changes that have been made.
2. Company Policy
This section states the company objectives and establishes the principles with which
company quality systems are expected to comply.
3. Company Organization
This section describes the activities of the company and sets out its management
structure. It defines the responsibilities attached to the principal managerial posts
and establishes the status and duties of the company quality assurance manager.
4. Company Instructions
This section schedules and describes all company instructions, which relate to the
management of quality and cross-reference them to the relevant items of standards.
5. Project Quality Assurance
This section sets out the procedures for the assignment of quality assurance
engineers to projects and outlines their duties. It then describes the preparation of
project quality plans and project procedures.
2.8 Factors Affecting Project Quality
Various attempts have been made by different researchers to determine critical
success factors in construction. The literature abounds with lists of variables
supposedly influencing the quality of a building construction project. There are
٢٥
some variables common to more than one list, but there is certainly no general
agreement on the variables. Review of this previous research variables reveals some
common threads of variables affecting the quality of a building project.
(Chan and Tam, 2000) stated that the generally perceived factors that influence
quality performance can be grouped under the headings of client, project
environment, project team leaders, project procedures and project management
procedures.
The client (Chan and Tam, 2000) Earlier research demonstrated that sophisticated clients (those having built projects
before) and specialized clients (repeated similar buildings) has a better chance of
success with their projects than novices. Other aspects of the client, such as the
nature of client (i.e. whether they are from the public or private sector), clarity of
project mission, their competency in terms of ability to brief, make decision, define
roles, etc, have been shown to influence the quality of a project.
The project (Chan and Tam, 2000) Project characteristics have a significant role to play in affecting quality
performance. That can be best defined in terms of project scope, nature of project
and complexity of project. Project scope refers to the type of project, the number of
stories and the sophistication of the project. Nature of the project defines whether it
is a new works project or a refurbishment project. Some projects are more expensive
to build than others. Refurbishment works tend to have a higher unit cost than new
works. Project complexity can be measured in terms of site access, design
buildability, design coordination, site conditions, and quality management.
The project environment (Chan and Tam, 2000) Environment can be considered as all external influences on the construction
process. Broadly, these may be grouped as physical, economic, socio-political, and
industrial relations, and they act at national or local level, and in different ways in
the public and private sectors. There have been dramatic changes in attitudes to the
environment over the past 30 years. These changes can create uncertainty, not
regarding prices, but also in terms of investment in the work of an organization,
which will affect the demand of quality.
٢٦
Project team leaders (Chan and Tam, 2000) The project team in the construction industry is that group of construction
professionals and personnel from one or more organizations who combine to fulfil
the necessary design, detailing and construction functions comprising the
construction projects. The management of construction projects involves many
diverse groups, client, designers, suppliers, sub-contractors, and the construction
management team and client consultants responsible for advising on progress in
terms of time, cost and quality. The performance of the team depends to a large
extent on the skills and experience of several key project team leaders: the client
representative, the design team leader, and the construction team leader.
The performance of the project team members can be assessed by their technical and
managerial skills, working relationship and attitude, and support from their parent
companies.
Project procedure (Chan and Tam, 2000) Quality performance has been considered as a function of the procedures adopted
during the construction process. Those procedures comprise the concept of
procurement form and the method of tendering. The fragmental nature of the
construction industry, the fact that no two construction projects are identical and the
resulting ephemeral nature of the project organization places great dependence on
the project team in setting up the construction process and bringing the project to a
successful conclusion. To ensure success, the selection of the most appropriate
organization for the design and construction of the project requires early and
particular attention.
In the main, the construction team will be appointed under competition through
competitive tendering process. Sometimes the head contractor may be appointed by
negotiation on the basis of a fee. In case when the design and construction is done as
a complete package, both may be let by competition. The selection procedures
applied to the members of the project team are therefore by no means always the
same. It was noted from research that competitive tendering can adversely affect the
outcome of major projects and the number of separate contracts is related to the
chances of success. Different selection methods will pose different levels of risk to
the project team members. Systems such as competitive tendering would involve a
٢٧
higher degree of risk to the team member, whereas cost reimbursement contracts
would be low risk bearing by comparison.
Project management actions (Chan and Tam, 2000)
The managerial system is primarily concerned with decision making for planning
and controlling organizational endeavor. The managerial subsystem can be seen as
spanning the entire organization by relating the organization to the environment,
setting the goals, developing comprehensive strategic and operational plans,
designing the structure and establishing control process. An integral element of the
managerial task is organizational decision making, choosing an overall strategy,
setting specific objectives, designing structures and processes, selecting people,
delegating responsibility, evaluating results and initiating changes.
The degree of project management actions can be reflected in the range and type of
control mechanisms set up for particular problem. At one end of the range there will
be a very low control situation, if professional design team, drawings, specifications,
documentation and standard form of contract do not exist. Minor works may fall into
this category. On the other hand a high control situation may exist if detailed
documentation is administered through a system of regular meeting, monitoring and
inspections.
(Abdel-Razeq, et al., 2001) stated that the construction process consists of
construction inputs, construction processing and construction outputs. Construction
inputs are defined as all resources and parties involved in the construction process.
Construction processing is the execution process, which can be defined as activating
construction inputs for executing construction activities. Construction output is the
construction facility (project). The main parties involved in construction phase are:
1) owner, 2) designer, 3) general contractor, 4) material supplier, 5) owner’s site
team, 6) contractor’s site team.
٢٨
The elements affecting quality of the construction process are the components of
both construction inputs and construction processing. These elements are collected
as shown in Figure 2.4 in the following ten elements:
1. Design: includes all things-related to design- come from the designer and/or
the owner side.
2. Contract: is the prime contract between the owner and the contractor.
3. Material: includes all things related to raw material and its suppliers.
4. Labor: includes all the main working labor in the project.
5. Equipment: includes the main working equipment in the project.
6. Subcontractors: includes the main subcontractors in the project.
7. Site layout planning: is the planning of the project site area.
8. Systems: includes any system, which can not put under the other nine
elements.
9. Site staff: includes the management teams and their shared tasks.
10. Execution: includes all things required to activate the above elements and to
execute the project activities.
Figure 2.4: The Proposed Concept of the Construction Process (Abdel-Razeq, et al., 2001)
Construction Inputs
Site Layout
Site Staff
Equip. Material Design
Systems Subs Labor Contract
Execution
Completed Project
٢٩
(Tan and Lu, 1995) grouped the elements affecting quality of the building
construction project into eight criteria and every criterion is divided into several
impacting factors as depicted in Table 2.2.
Table 2.2: Impacting factors affecting quality of a construction building project
No Quality criteria Impacting factors
1. Manpower qualified to achieve project mission, requirements, and objectives.
Capability of project manager Capability of design staff Capability of supporting staff
2. Conformance to codes and standards. Owner’s willingness to abide by the agreed rules and standards. Utilization of the correct edition and articles. Consistency of the rules and standards.
3. Conformance to owner’s requirements.
Accuracy of owner’s stipulated requirement. Clarity of owner’s requirements. Changes to owner’s requirements
4. Conformance to design process and procedures
Completeness of engineering design manuals, and guidelines. The effectiveness of the quality control program. The enforcement of engineering change control.
5. Conformance to schedule requirements
Monitoring and control of schedule and performance Number of engineering design changes Reasonableness of the schedule
6. Conformance to cost requirements Number of engineering changes Clarity of the scope of work and statement of work Reasonableness of the cost estimates and budget
7. Completeness of and conformance to output standards
Completeness of data and information Clarity of illustrations and classifications Consistency of the contents Accuracy of the data and methods
8. Constructability Timeliness and completeness of supply of equipment and material Utilization of common and standardized construction methods and materials Audit of design for Constructability
٣٠
In another study, (Abdel-Razeq, 1998a) identified the factors affecting quality.
These factors can be summarized in the following sixteen elements:
1. Design and planning during the pre-construction phase.
2. Developing and improving quality assurance and control systems.
3. The financial level and standard of living of employees.
4. The accuracy of cost estimating.
5. Proper classification of contractors, consultants and projects.
6. Employees’ consciousness.
7. Training for contractors, owners and consultants.
8. Encouraging ISO 9000.
9. Contractors’ technical and managerial efficiency.
10. Maintenance systems during and after construction.
11. Utilization of resources.
12. Specialization in construction work.
13. Co-operation between construction industry and scientific organizations.
14. Participating and co-operating with advanced international organizations.
15. Defining responsibilities between project parties.
16. Encouraging innovation for simpler and more accurate work methods.
The factors which have an effect on the quality of a construction building project
were already identified by (Low and Goh, 1993 cited in Low and Peh, 1996). These
are ranked below in their order of importance:
1. Poor workmanship by the contractors in completing the works results from
low tender prices.
2. The drawings and specifications do not specify clearly the intentions of the
designers. Discrepancies are found between different consultant’s drawings,
which have resulted in poor co-ordination during construction.
3. The contractors pay more attention to complete the works on schedule and
control the costs to within budget than to achieving quality in construction.
٣١
4. Poor co-ordination exists between the contractors and the subcontractors as
well as the nominated subcontractors.
5. The designers do not consider the “buildability” problems in design. For
example, the designers do not consider the use of special construction methods
to achieve the tight tolerance caused by site conditions.
6. The contractors cannot plan and control the works. The contractors lack the
skills to interpret the design and cannot provide the end products on site in
accordance with the design and specifications.
7. The completion period fixed by the client and consultants is not realistic.
8. The design does not satisfy the relevant codes and standards. This has
resulted in a large amount of remedial work for the contractors and delay in the
completion of projects.
9. The contractors do not know how to establish a quality system to control the
works.
10. The materials chosen by the consultants do not satisfy the standards or the
Building Control Authority.
2.9 Modeling Concept
A model is a physical or symbolic representation of the relevant aspects of the
reality or system, which are in concern. In other words, a model is a means of
portraying the system or reality of concern to the decision-maker. As such, the
concept of a model generally implies a series of connected and identifiable
relationships that essentially demonstrate the proposition of this action, then the
result. (Taha, 1989) defined the model as “the model is an abstraction of the
assumed real system, identifies the pertinent relationships of the system in the form
of an objective and a set of constraints”.
Models can be of several types, but common models are as under:
• Iconic model: is a pictorial or visual representation of certain aspects of a
system. In iconic models the relevant properties of the real thing are represented
by the properties themselves, usually with a change of scale.
٣٢
• Analogue model: use one set of properties to represent another set of
properties. They are more abstract than iconic models. Such models are easier to
manipulate and can represent situation. Graphs representing time series, flow
charts, demand curves, frequency graphs are examples of analogue models.
• Symbolic or Mathematical model: in this model, the components of what
is represented and their inter-relationships are given by symbols. These models
use letters, numbers and other types of symbols to represent variables and the
relationship between them. Such models assume the form of equations or
inequalities depicting the relationships amongst the variables of the system
(Kothari, 1982).
Model formulation can be done by following the two steps below ( Kothari 1982):
• Abstraction: it happens to be the first step in modeling and consists of
selecting the critical factors or variables from the empirical situation. There are
usually an uncountable number of facts in any empirical situation and the
decision-maker must intelligently abstract those factors, which he considers to
be most relevant to the problem he is facing.
• Model Building: the relevant factors or variables selected are put in some
logical manner so that they form a model of the given problem. In model
building it is generally considered desirable to simplify reality but only to the
point where there is no significant loss of accuracy.
2.10 Quality Modeling Former Studies
Several studies and reports were written to highlight the factors affecting quality in
construction projects and developed different types of models.
In 1994, CII (Construction Industry Institute) developed a model called the Quality
–Measurement Matrix (Stevens, 1994). It is an effective device for cataloging
quality performance measurements on engineer-procure-construct (EPC) project. It
focused on four elements of TQM: consumer focus, leadership, delivering, and
employee empowerment. Continuous improvement, the major goal of TQM, is not
listed as a separate element but is considered to encompass all other TQM process.
٣٣
The quality-measurement-matrix form is shown in Figure 2.5. The ordinate uses
TQM process elements and associated categories. The abscissa uses a location key,
which indicates the location of the complete project; phases which indicate the
project phases that the measure may be applicable for; metric, which identifies the
specific unit of measures employed; and how it is used, to provide a brief
explanation of how each measure can be used in the engineer-procure-construct
(EPC) project (Stevens, 1994).
TQM process
elements
Location
Key
Phases * PP DS PR CO OP SU FD
Metric or
Tool
How
Used
Customer focus
Leadership
Delivery
Employee
Empowerment
*(PP) preplanning, (DS) design, (PR) procurement, (CO) construction,
(OP) operation, (SU) startup, (FD) final disposition
Figure 2.5: Quality Measurement Matrix (Stevens, 1994)
A second study developed by CII was a prototype methodology which was called
“the blueprint” to assist companies in measuring quality performance on engineer-
procure- construct (EPC) project. The blueprint leads a project team through the
steps to identify and develop predictive measurements for project quality and it
helps the team to determine the critical measurements needed for a specific project.
In addition, it provides a mechanism to improve communications.
The flowchart shown in Figure 2.6 shows the steps of implementation of “the
blueprint”. It depicts the responsible parties involved and the steps necessary for
implementing this process into a project management system (Stevens, 1996).
٣٤
Owner defines the Business Objectives
A Business Management Team (BMT) is formed representing each
organization responsible for all major phases of the project
The Team determines all the major inputs, outputs and customer/supplier relationships for each major project phase. The team then decides how and when to measure.
The team translates the business Objectives into specific Project Objectives.
The Team analyzes the key elements that impact the Project Objectives. The team then determines what should be measured.
For each major phase of the project, the team selects the critical few
measurements that align with the key elements that impact the
project objectives.
The Team defines the targets (or benchmarks) for each key measurement area, the person responsible and the frequency of
measurement for each major project phase.
The BMT creates the Project Management Team (PMT) and communicates all of the information generated above. The PMT
performs virtually the same steps above, generating a more detailed breakdown of objectives, measurements and insuring alignment with
the BMT's directions.
The BMT determines the Project Phase Model to be used. Each
Team Member is assigned responsibility for one or more of the
major project phases.
٣٥
Figure 2.6: Flowchart of Blueprint Process (Stevens, 1996)
(Abdel-Razeq, et al., 2001) developed a model through their study on factors
affecting quality of construction projects in Egypt. A questionnaire was used to
define the most main factors affecting quality. The model which was developed is
shown in the form below:
Project construction quality = (D + C + M + L + E + SUB + SL + SYS + SS + EX) *
(100/50)
Where:
• D, C, M, L, E, SUB, SL, SYS, SS, and EX are average weighted scores of
Design, Contract, Material, Labor, Equipment, Subcontractors, Site Layout, Site
Staff, and Execution respectively.
• 50 = the summation of maximum scores of ten elements
= 10 elements * maximum score of the element (i.e. 5)
(Chan and Tam, 2000) developed a model to measure quality of a construction
building project through their study on factors affecting quality in Hong Kong. The
methodology used was based on interviews with project managers to define the
factors affecting quality, then developing a questionnaire used a seven-point scale
asking for ranking these factors to give weights for them. Factor analysis and
multiple regression were used throughout the development of the modeling process.
The model which was developed can be expressed in the following form:
Quality = 5.2 + 0.50 MAN-ACT + 0.08 EFF-CON – 0.30 CLI-QUA – 0.38 CLI-TIME
Where:
MAN-ACT : Project management action
The PMT creates the technical and craft teams to go through the same process outlined above.
٣٦
EFF-CON : Effectiveness of construction team leader
CLI-QUA : Client’s emphasis on quality
CLI-TIME : Client’s emphasis on time
CHAPTER 3
METHODOLOGY
In order to realize the study objectives which are: to define the factors affecting
quality of a building construction projects; to derive the relative weights of these
factors; and to develop a model to represent these factors used as a tool to measure
quality. The methodology adopted in this research can be summarized in the
following points:
• Nominal Group Technique
• Defining the factors affecting quality of the building construction project
• Developing a research model
• Design a questionnaire
• Instrument validity (validity of the questionnaire)
• Research sample
• Method of collecting data
• Instrument (questionnaire) reliability
• Method of data analysis
• Model verification
The research methodology is shown in the following Figure 3.1.
٣٧
RESEARCH METHODOLOGY
FORMER STUDIES QUALITY FACTORS (INTERNATIONAL)
NGT QUALITY FACTORS
(LOCAL)
QUESTIONNAIRE DESIGN
RANKING SUB-FACTORS
RANKING MAIN FACTORS
WEIGHTED AVERAGE
APPROACH
PARETO ANALYSIS APPROACH
FACTOR ANALYSIS APPROACH
STEPWISE MULTIPLE
REGRESSION APPROACH
MODEL 1 MODEL 2 MODEL 3 MODEL 4
SELECT THE APPROPRIATE MODEL
MODEL VERIFICATION (TWO CASE STUDIES)
٣٨
Figure 3.1: Research Methodology
3.1 Nominal Group Technique
The primary data were obtained from the participants through the application of the
Nominal Group Technique (NGT), one of many structural processes that have been
designed and developed. The NGT takes its name from the fact that it is a carefully
designed, structured, group process that involves carefully selected participants in
some activities as independent individuals, rather than in the usual interactive mode
of conventional groups (Abdel- Razek, 1998b). It is a special-purpose technique,
useful for situations where individual judgements must be tapped and combined to
arrive at decisions that cannot be reached by one person. The NGT is a problem
solving or idea-generating strategy. It is a well-developed and tested method that is
fully presented in the work of (Delbecq, et al., 1975 cited in Abdel-Razek, 1998b).
Since its development in 1968, the NGT has gained extensive recognition and has
been widely applied to identify factors affecting quality. The session group consists
of at least twenty participants and the session is controlled by a process consultant
and an assistant. The duration of the session is about three hours (Abdel- Razek,
1998b).
In this study, the application of the NGT was carried out in the Islamic University of
Gaza with the writer of this research acting as the facilitator. Twelve consultants,
eight contractors, six owner’s representatives were invited to attend the session.
The participants classification is shown in Table 3.1 below.
Table 3.1: Participants attended NGT session
Consultant Contractor Owner
DESIGN EXCEL SHEET (MEASUREMENT TOOL)
٣٩
7 9 6
The session objective was to obtain, from the attendants, a consensus conclusion on
the factors affecting quality of construction building projects during construction
phase in Gaza Strip.
NGT has four phases in addition to an introduction, task statement and conclusion.
The first phase is called silent generation. During this phase, the group members
were instructed to write their responses to the task statement. In this study, the task
statement was “ State all the factors that you think will affect the quality of
construction building projects during construction phase”. For this portion of the
session individual behavior is sought. Silent generation focuses attention on a
specific task, frees the participants from distractions, and provides them with an
opportunity to think through their ideas rather than simply reacting to the comments
of others. In this sense, it is a search process that yields contribution of greater
quality and variety (Abdel- Razek, 1998b).
The second phase is the round-robin phase. The facilitator calls on participants to
engage in groups. Each group discusses the individual ideas, agrees and records on a
list of ideas. This phase goes until all the ideas generated by the group are listed and
displayed. The process separates ideas from their authors and permits conflicting
and incompatible ideas to be explicitly tolerated. It provides a written record of the
groups efforts as a basis for any step.
The third phase is called clarification. Once all the ideas have been recorded, any
participant from each group may offer clarification or may suggest combination,
modification, or deletion of ideas to produce a list of the factors affecting quality.
The fourth phase, voting and ranking, provides the participants with an opportunity
to select the most important factors and to rank and weight those factors. The most
important factor takes five points, the second most important factor takes four and so
on, until the least important factor which takes one point (Abdel- Razek, 1998b).
٤٠
The session closes with a brief discussion of the results of the voting process in
which the facilitator emphasizes those factors on which there is strong consensus.
The NGT session generates 8 main factors and 16 sub-factors affecting quality of a
building construction project. Combining these factors with the others factors
resulted from literature review will be used as a base to develop a questionnaire used
as a research tool of this study. The forms used in NGT session and the results are
found in Appendix (A).
3.2 Defining the Factors Affecting Quality of a Construction Building
Project in Gaza Strip A thorough literature review was conducted to identify the factors that affect quality
as recognized by researchers and practitioners in this field. Combining this literature
review as discussed in chapter 2 with the results of the Nominal Group Technique
session, the factors affecting quality were identified. They are categorized into
fourteen groups (main factors). Each group is divided into sub-factors as shown in
Table 3.2.
Table 3.2: Factors Affecting Quality of the Construction Building Project
No Main Factor Sub-factors
1.
Project
Scope of the project (type and nature)
Location of the project
Site access
Period of the project
2.
Design
Completeness and consistency of design documents
Drawings are prepared in full details
Conformance to codes and standards
Adherence to specifications
Bill of quantity is very detailed and accurate
٤١
3.
Contract
Cooperation between parties involved in contract
Pervious successful relations between parties
A written contract with clear conditions
Using a standard contract
Types of awarding system
4.
Materials
Using a comprehensive material management system
Cooperation between contractor and material suppliers
Availability of good quality construction materials
Using storage and handling system
Construction materials monopoly
5.
Labors
Labor management system
Using labors with high experience
Using motivation system
Training courses for labors
Income level and wages of labors
6.
Equipment
Availability of equipment
Equipment management system
Measurement of equipment productivity
Good utilization of equipment
Equipment maintenance
7.
Subcontractors
Company’s procedures of selecting subcontractors
High cooperation between subcontractors and general
contractor
Using a system to evaluate subcontractors performance
Good and fair subcontract conditions
8.
Site layout
Site layout is large
Site layout is organized well
Site layout has storage areas for materials
Site layout is clean
٤٢
9.
Systems
Using computer software and applications
Implement quality control and assurance system
Using time schedule
Using cost control system
Implementing a safety program
10.
Site staff
Cooperation between Supervision and Contractor’s staff
Understanding of contract administration by Supervision
Skill and experience of Supervision staff
Skill and experience of Contractor’s staff
11.
Execution
Using a complete execution system
Testing for final products only
Clear procedure for accepting performed activities
Preparing and using shopdrawings
12.
Financial Issues
Amount of contractor’s cash flow
Nondelay of interim payments
13.
Owner
Nature of Owner’s organization ( Public or Private)
Owner’s quick response (no delays in making decisions)
Owner’s contribution to design
Owner’s emphasis on quality
14.
Environment
Socio-economic environment
Stability of Political environment
Closure of Gaza Strip
The relations between construction industry and other industries
3.3 Development of the Research Model
Based on the main factors and sub-factors affecting quality generated from
combining the results of NGT session and literature review, a research model was
developed to facilitate the research study. The model depicts the relationships
between the variables in the construction process. The aim of the model is to
facilitate investigations on factors, which are important for achieving an outstanding
quality performance and how these factors relate to quality. The model can also
assist in determining how important are these factors when they are used to predict
٤٣
quality. The research model is represented in Figure 3.2. Fourteen independent
variables were used in the model, namely:
1. Project variables. 2. Design variable. 3. Contract
variables.
4. Material variables. 5. Labor variables. 6. Equipment variables.
7. Subcontractors variables. 8. Site layout variables. 9. Systems variables.
10. Site staff variables. 11.Execution variables. 12. Financial variables.
13.Owner variables. 14.Environment variables.
The impact and interaction of these independent variables will determine the
dependent variables, which is, in this study, quality performance.
٤٤
3.4 Developing the Questionnaire
Using the research model shown in Figure 3.1, an eight-page questionnaire was
developed as a research tool for this study, see Appendix (B). The questionnaire
consists of four sections:
Section one: respondents information (Company profile).
Section two: asked to what extent the quality concept is understood in the company.
Section three: respondent’s rank of the main factors affecting quality. This section
aims to make comparison between scores resulted from ranking the main factors
presented in it and scores resulted from ranking the sub-factors presented in section
four. This comparison will check the priority order of main factors in both ranking.
Section four: respondent’s rank of the sub-factors affecting quality. As this section
contains sub-factors affecting quality correlated to their main factors, it will be used
as a base for all statistical analysis approaches.
The questions in Sections three and four were so designed to measure the variables
addressed in Figure 3.2. The form of questioning varied from factual data to
subjective responses. The main objective in question design is to make questions
asked clear, concise and unambiguous. Extensive use was made of ordinal scale
measures for eliciting data on respondent’s perceptions. The ordinal scale is a
٤٥
ranking or a rating data which normally uses integers in ascending or descending
order. The respondents were asked to assess the main factors and sub-factors
affecting quality in construction projects on a five point scale, where 1 represents
very low important, 2 represents low important, 3 represents medium important, 4
represents important and five represents very important. The questionnaire is shown
in Appendix (B).
3.5 Instrument Validity
The questionnaire was reviewed by a group of experts in the field of the study. They
were requested to identify the internal validity and to what extent it was suitable to
be used as an instrument to realize the goals and aims of this research.
The group of experts has agreed that the questionnaire is suitable to achieve the
studying goals with some amendments. The researcher has made these amendments
in the structure and language of the questionnaire to be consistent with the local
environment.
The names of experts group are found in Appendix (C).
3.6 Research Sample
Two types of population were considered in this study. The first population is the
Contracting Companies of First Class “A”, First Class “B”, Second Class and Third
Class, who were registered by the Contracting Union in Gaza Strip, at year 2002.
Ninety two Contracting Companies are registered.
The second population is the Engineering Consulting Offices, who were registered
by the Engineering Association in Gaza Strip at year 2002. Twenty seven
Consulting Offices are registered.
3.6.1 Sample Size
To choose the sample size from the first population (contracting companies), which
equal 92 company, the formula shown below was used for unlimited population
(Creative Research System, 2001):
٤٦
Where SS = Sample size
Z = Value (e.g. 1.96 for 95% confidence level)
P = Degree of variance between the elements of population (0.5)
C = Confidence interval (.05).
= 384.16 = 385
Correction for Finite Population, use the formula below:
Where: POP= population
= 74.4 = 75
As the second population which is the Engineering Consulting Offices is small, the
whole population (27 offices) was taken as the concerned sample size.
3.7 Method of Choosing the Sample
The Contracting Companies consist of four classes or categories. Due to this
formation, the Stratified Random Sampling was used. Random choosing of each
class was used one by one until reaching the number of companies needed for each
class as shown in Table 3.3.
2
2 )1(C
PPZSS −××=
2
2
05.0)5.01(5.096.1 −××
=SS
POPSSSSNewSS
11 −+
=
9213851
385−
+=NewSS
٤٧
Table 3.3: Classification of sample size of the Contracting Companies
Class No. of Companies % from the whole
population
No. needed from
the concerned
sample size (75)
First “A” 18 20% 15
First “B” 24 26% 20
Second 39 42% 31
Third 11 12% 9
Total 92 100% 75
3.8 Instrument (Questionnaire) Reliability
Reliability of internal consistency was used to test the reliability of the
questionnaire. The reliability coefficient of the scale was established by Cronback’s
alfa using SPSS package, which reflected alfa coefficient to be 0.8311. It is
considered to be highly significant at 0.05 level and this ensures the reliability of the
scale.
3.9 Method of Collecting Data
The personal interview was used for filling the questionnaire and collecting data. It
is a face-to-face interview in which the interviewer asks the respondents questions
and make a brief clarification for the ideas included in the questionnaire.
The respondents who agreed to cooperate in filling the questionnaire are detailed in
Table 3.4.
Table 3.4: Number of the questionnaire respondents
Type Concerned Sample
Size
No. of Respondents Percentage
Contracting 75 65 87%
٤٨
Companies
Engineering
Consulting
Offices
27 24 89%
3.10 Method of Data Analysis
The data was analyzed using SPSS package. As will be discussed in Chapter 4,
descriptive statistics such as frequency and percentage were computed for each item
in the questionnaire. Factor Analysis was performed to allow finding a small number
of underlying dimensions from among a large number of variables. Finally, a
stepwise multiple regression analysis was performed to assess the strength of the
relationship between contextual variables and quality. By using stepwise multiple
regression, the model representing the quality and the factors affecting it was
developed.
3.11 Model Verification
The developed model was tested for two projects to realize the effectiveness and
practicality to use it for measuring quality of construction building projects in Gaza
Strip.
٤٩
CHAPTER 4
DATA PRESENTATION AND ANALYSIS
Analysis of data will be done through two statistical analysis methods. The first
method which is called “The Descriptive Statistics Method” provides a general
overview of the results. It gives an idea of what is happening. The other method
which is called “The Inferential Statistics Method” provides different statistical tests
to be applied for different parts of the sample to make comparison of results.
4.1 The Descriptive Method
This method was applied on the survey data collected in Section 1 and Section 2 of
the questionnaire. Frequency distribution and the percentage of different items are
presented. The scores of the main factors and sub-factors affecting quality of the
construction project collected in Section 3 and Section 4 of the questionnaire are
also presented in the following sections.
4.1.1 Section 1: Company Profile
1. Type of Organization
٥٠
65 contracting companies and 24 consulting offices participated in the
questionnaire.
Figure 4.1: Type of Organization
2. Year of the Company Establishment
As depicted in Table 4.1, it is clear that most of the surveyed companies (47.2 %)
were established in the years 1994 and 1995 after the establishment of the
Palestinian Authority.
Table 4.1: Establishment Year of Companies
Year of
Establishment
Frequency Percent %
1974
1980
1981
1982
1984
1985
1986
1987
1989
1990
1991
1
1
1
1
2
3
1
1
1
2
1
1.1
1.1
1.1
1.1
2.2
3.4
1.1
1.1
1.1
2.2
1.1
consultant
contracting
٥١
1992
1993
1994
1995
1996
1997
1998
1999
2001
Total
2
9
24
18
10
2
4
4
1
89
2.2
10.1
27
20.2
11.2
2.2
4.5
4.5
1.1
100
3. Classification of Contracting Companies
Four classes of Contracting Companies are surveyed as shown in Table 4.2. It is
noted that (52.2 %) of the investigated contracting companies are classified as first
class A and B who represent the top class of the construction sector. According to
their long experience, the questionnaire results will represent the actual situation of
the factors affecting quality.
Table 4.2: Classification of Contracting Companies
Classification Frequency Percent %
First class “A”
First class “B”
Second class
Third class
Total
19
15
26
5
65
29.2
23.0
40.0
7.8
100
4. Position of Respondent
As shown in Figure 4.2, most of the respondents (64%) have the title of Managers.
This indicates the high cooperation of those managers in this study, their concern in
site engineer 10.1%
٥٢
the subject under investigation and reflects the conformity of the results of the
questionnaire.
Figure 4.2: Position of respondent
5. Number of Company Staff
As shown in Table 4.3, most of the companies (73%) have less than 10 employees
and this indicates that the contracting and consulting firms are small size companies
compared with the other regional countries.
Table 4.3: Number of Company Staff
No. of employees No. of Companies Percent %
Less than 10
From 11 to 20
From 21 to 30
From 31 to 50
More than 50
Total
65
19
1
3
1
89
73
21.4
1.1
3.4
1.1
100
6. Type of Projects the Companies are Dealing with
Figure 4.3 shows that (64%) of the surveyed companies are dealing with both
building construction and infrastructure projects as those two fields are the
prevailing construction fields in Gaza Strip.
٥٣
Figure 4.3: Type of projects the companies are dealing with
7. Number of projects executed in the last five years
As shown in Figure 4.4, (56.2 %) of the companies’ volume of work is from 11 to
30 projects in the last five years, which means an average of four projects per year.
Also (29.2 %) of the companies have a volume of work of more than 30 projects in
the last five years. This indicates that these companies have a very good experience
that enables them to identify the most important factors affecting quality.
Figure 4.4: Number of projects executed in the last five years
8. The value of projects executed in the last five years
Infrastructure+ buildings٦٤%
Buildings٣٤.٨%
Infrastructure ١.٢%
Morethan 3020.2%
From 21to 30(23.6%)
From 11to 20(26.6%)
Less than 1014.6%
٥٤
From Figure 4.5, it is noticed that (50.6%) of the companies have executed a volume
of work with a value from 2 to 5 million dollars which means that the local
construction projects are mainly small to medium projects compared to wide world
construction projects.
Figure 4.5: The value of projects executed in the last five years
4.1.2 Section 2: Quality in the Organization
The second part of the survey prompted the respondents about their perception and
knowledge of quality.
9. The Understanding of Quality Concept by Company Staff
The results are as shown in Table 4.4. It is evident that the understanding of quality
is good but not sufficient. As (37.1%) of the respondents have not a clear definition
of quality, this indicates that there is a need for studies in this subject to clarify the
quality concept to all parties of the construction industry.
Table 4.4: The Understanding of Quality Concept by Company Staff
Item Frequency Percent %
Yes
No
No answer
Total
56
11
22
89
62.9
12.4
24.7
100
10. Percentage of employees concerned of quality
More than 8 million(15.7%)
From 5 to 8 (16.9%)
From 2 to 5(50.6%)
Less than 2 million(16.8%)
٥٥
As shown in Table 4.5, it is clear that most of the companies’ employees are
concerned with quality and its implementation. (62.9 %) of the companies have
(51%) to (100%) of their employees asserted with the importance of quality, while
(37.1%) of them have (10%) to (50%) of their employees are aware of the
importance of quality. This result also supports the fact that there is a consciousness
about the importance of quality during construction of the project.
Table 4.5: Percentage of employees concerned of quality
Percentage of employees Frequency Percent %
From 10-50 %
From 51-99 %
100 %
Total
33
29
27
89
37.1
32.6
30.3
100
11. Implementation of Quality System
The results are as shown in Table 4.6. (43.9 %) of the companies have implemented
a quality system and (44.9%) have the intention to develop and implement a quality
system. A small number of companies (11.2%) has not implemented a quality
system. This indicates the high concern of quality importance and its effect
onconstruction projects. Also it gives a good picture about the construction industry
in Gaza Strip that it is a developing industry and in the way to reach high standards.
Table 4.6: Implementation of Quality System
Item Frequency Percent %
No
Under consideration
Implemented recently
Implemented for some time
Total
10
40
7
32
89
11.2
44.9
7.9
36.0
100.0
12. Top Management support for quality
٥٦
The results are as shown in Table 4.7. (97.8%) of top management of the companies
support the implementation of a quality system in the company. Also this indicates
the high concern for quality and its importance in the construction industry.
Table 4.7: Top Management support for quality
Item Frequency Percent %
Yes
No
No answer
Total
87
0
2
89
97.8
0
2.2
100
13. Companies having ISO Certificate
Just 5 contracting companies out of 65 have ISO certificates. The high cost of
getting ISO certificate limited the number of companies who have this certificate.
None of the consulting companies has ISO certificate.
14. The year of having ISO certificate
The five companies who have ISO certificate got their certification in the period of
1997-1999. In this period, there was a stability in the political situation and a large
volume of construction projects. This encouraged some contracting companies to
have ISO Certificate to be able to enter the competition in international market.
4.1.3 Section 3: Main factors affecting quality of construction projects
This section was developed in the questionnaire to cross check the scores resulted
from ranking the main factors compared with the scores of the same main factors
resulted from ranking the sub-factors in Section 4. The scores of the main factors are
presented in Table 4.8 in order of highest score to lowest score.
Table 4.8: Scores of the main factors affecting quality
٥٧
No. Quality Main Factor Score
1 Site staff 406
2 Design 399
3 Financial issues 395
4 Subcontractors 393
5 Material 370
6 Labor 368
7 Systems 364
8 Environment 363
9 Contract 361
10 Execution 333
11 Equipment 328
12 Project 325
13 Owner 310
14 Site layout 273
4.1.4 Section 4: Sub-factors affecting quality of construction projects
Scores of each of the sub-factors affecting quality in construction projects are
presented in Table 4.9. (Raw Data are presented in Appendix F)
Table 4.9: Scores of the sub-factors affecting quality of construction projects
No. Main Factor Quality Sub-factor Score
Scope of the project 335
Location of the project 302
Site access 307
1. Project
Period of the project 321
Completeness and consistency of design documents
407
Drawings are prepared in full details 403
Conformance to codes and standards 386
Adherence to specifications 413
2. Design
Bill of quantity is very detailed and accurate 397
3. Contract Cooperation between parties involved in contract 370
٥٨
Previous successful relations between parties 315
A written contract with clear conditions 371
Using a standard contract 333
Type of awarding system 354
Using a comprehensive material management system
367
Cooperation between contractor and material suppliers
359
Availability of good quality construction materials 397
Using storage and handling system 356
4. Material
Construction materials monopoly 352
Labor management system 406
Using labors with high experience 413
Using motivation system 338
Training courses for labors 320
5. Labor
Income level and wages of labors 340
Availability of equipment 375
Equipment management system 319
Measurement of equipment productivity 303
Good utilization of equipment 350
6. Equipment
Equipment maintenance 333
Company’s procedures of selecting subcontractors 393
High cooperation between subcontractors and general contractor
383
Using a system to evaluate subcontractors performance
357
7. Subcontractors
Good and fair subcontract conditions 363
Site layout is large 340
Site layout is organized well 343
Site layout has storage areas for materials 333
8. Site layout
Site layout is clean 313
Using computer software and applications 343
Implement quality control and assurance system 375
9. Systems
Implement and using time schedule 385
٥٩
Using cost control system 350
Implement a safety program 342
Cooperation between supervision and contractor’s staff
415
Understanding of contract administration by supervision
400
Skill and experience of supervision staff 409
10. Site staff
Skill and experience of contractor’s staff 422
Using a complete execution system 407
Testing for final products only 199
Clear procedure for accepting performed activities 360
11. Execution
Preparing and using shopdrawings 381
Amount of contractor’s cash flow 410 12. Financial
issues Non delay of interim payments 390
Owner organization’s nature (public or private) 309
Owner’s quick response (no delays in making decisions)
351
Owner’s contribution to design 317
13. Owner
Owner’s emphasis on quality 340
Socio-economic environment 327
Stability of political environment 381
Closure of Gaza Strip 401
14. Environment
The relations between construction industry and the other industries
313
To calculate the average score of each main factor above, the summation of scores
of each sub-factor is divided by the number of sub-factors belonging to the same
main factor.
Example: Average score of main factor “Project”= (335+302+307+321) / 4
=316.25
The average scores of the main factors resulted from ranking the sub-factors
affecting quality is presented in Table 4.10 in order of highest score to lowest score.
٦٠
Table 4.10: Average scores of main factors resulted from ranking sub-factors
affecting quality.
No. Quality Main Factor Score
1 Site staff 411.50
2 Design 401.20
3 Financial issues 400.00
4 Subcontractors 374.00
5 Material 366.20
6 Labor 363.40
7 Systems 359.00
8 Environment 355.50
9 Contract 348.60
10 Execution 336.75
11 Equipment 336.00
12 Site layout 332.25
13 Owner 329.25
14 project 316.25
Comparing the results shown in Tables 4.8 and 4.10, it is clear that the main first
eleven factors have the same order of priority in both methods of ranking and the
last three factors have slightly different order. This indicates the validity of the
questionnaire and the consistency in the results, which reflect the attitudes of the contracting
and consulting companies towards the most important factors affecting quality of
construction projects.
4.2 Inferential Statistics
Essential statistical testings are used to verify some basic elements in the structure of
the questionnaire. Summary of these testings are shown below.
4.2.1 T-test
The T-test was conducted to find if there is a significant difference between the
ranking of contracting and consulting companies towards the importance of quality
٦١
factors. T-test was carried out on the average weighted factors resulted from ranking
the sub-factors affecting quality in section 4 of the questionnaire.
The research question:
Do contracting and consulting companies perceive quality factors differently?
The research hypothesis:
There is a significant difference in perception between contracting and consulting
companies with regard to factors affecting quality. This difference is related to
management techniques, resource management, motivation, and experience.
The null hypothesis:
There is no difference in perception of quality factors between contracting and
consulting companies.
Statement of hypothesis testing:
Table 4.11 shows that there is a high correlation in the ranking of the two samples.
Hence, the null hypothesis can be accepted concluding that the contracting and
consulting companies do not perceive factors affecting quality differently. There is
an exception of this hypothesis in regard to the “Owner” factor. The results show
that there is a significant difference in ranking this factor. (P-value less than 0.05).
Table 4.11: T-test results comparing the ranking of contracting and consulting
companies for quality factors.
Contracting Co. N=65 Consulting Co. N=24 Factors
Mean Std.
Deviation
Mean Std.
Deviation
t-value P-value
٦٢
Project
Design
Contract
Material
Labors
Equipment Subcontractor
Site layout
Systems
Site Staff
Execution
Finance
Owner Environment
3.523
4.501
3.910
4.126
4.070
3.713
4.219
3.676
3.972
4.642
3.757
4.576
3.584
4.026
0.782
0.431
0.616
0.604
1.434
0.683
0.610
0.866
0.624
0.430
0.528
0.560
0.575
0.626
3.635
4.525
3.933
4.083
4.116
3.941
4.156
3.885
4.200
4.572
3.854
4.270
4.010
3.906
0.859
0.653
0.579
0.612
0.618
0.548
0.499
0.699
0.621
0.463
0.275
0.675
0.578
0.646
0.585
0.196
0.156
0.295
0.151
1.466
0.453
1.057
1.529
0.661
0.851
2.161
3.088
0.799
0.560
0.845
0.877
0.768
0.880
0.146
0.652
0.293
0.130
0.510
0.397
0.055
0.004 **
0.426
* Significant at 0.05 level
** P-value =0.004 less than 0.05, there is a significant difference between
contracting and consulting companies in ranking the Owner factor.
According to Table 4.11, both contracting and consulting companies have the same
attitude towards ranking most of the quality factors. This may be attributed to the
fact that they work under the same conditions and they are passing almost the same
experience through implementing the several stages of the construction projects.
It is seen that there is a significant difference in ranking “Owner” factor between
contracting and consulting companies. This can be interpreted by the fact that the
owner and consulting company have a direct relationship during implementation of
the construction projects, while the relation between the owner and contracting
company is usually passing through the consultant. This makes the consulting
company perceives the role of owner towards improving quality different from the
contracting company.
٦٣
4.2.2 The Spearman (rho) correlation coefficient test
As the number of contracting companies which have an ISO certificate is 5 and T-
test must be done if the sample is more than 5 (Fellows and Liu, 1997). Therefore,
the Spearman correlation coefficient will be used to find if there is a significant
difference between the ranking of contracting companies, who have an ISO
certificate, and the other companies who do not have such a certificate. The
Spearman test was made on the average weighted factors resulted from ranking the
sub-factors affecting quality as shown in section 4 of the questionnaire.
The research question:
Do Contracting Companies who have an ISO certificate differ in ranking the quality
factors from the other companies who do not have this certificate?
The research hypothesis:
There is a significant difference in perception between contracting companies who
have an ISO certificate and the other companies who do not have it with regard to
the factors affecting quality.
The null hypothesis:
There is no difference in the ranking factors affecting quality between the
contracting companies who have an ISO certificate and the other companies.
Table 4.12 shows the data of ranking factor affecting quality by both the companies
who have ISO certificate and those who do not have it.
Table 4.12: Spearman test results
Factors Average ranking of
companies having
ISO certificate.
“A”
Average ranking of
companies not having
ISO certificate
“B”
Difference in
ranks
Di=A-B
Difference in
ranks square
Di2
=(A-B)2
Project 3.2 3.55 -0.35 0.123
Design 4.52 4.5 0.02 0.0004
٦٤
Contract 4.16 3.89 0.27 0.072
Material 4.48 4.09 0.39 0.152
Labors 4.4 3.87 0.53 0.280
Equipment 4.28 3.66 0.62 0.384
Subcontractors 4.5 4.19 0.31 0.096
Site layout 3.4 3.7 -0.3 0.09
Systems 4.0 3.97 0.03 0.0009
Site staff 4.55 4.65 -0.1 0.01
Execution 3.9 3.74 0.16 0.025
Finance 4.4 4.59 -0.19 0.036
Owner 3.4 3.6 -0.2 0.04
Environment 4.35 4.0 0.35 0.122
Total Di2 = 1.431
To calculate the Spearman rank correlation coefficient (rho), the following formula
is used (Naoum, 1998):
Where, Di = the difference in ranking between each pair of factors
N = number of factors
= 0.997
For any number of factors N, if the value of the calculated (rho) is equal to or larger
than the critical values of (rho) shown in Table 4.13 at the same number of factors N
)1(6
1 2
2
−−= ∑
NNDi
rho
)1196(14431.1*61−
−=rho
٦٥
and at a certain level of significance, then there is a significant correlation between
ranking the factors. (Naoum, 1998)
According to Table 4.13, the critical value of (rho) is 0.456 at the significant level
P=0.05, and at the number of factors N equals 14. It is clear that the calculated value
(rho=0.997) is more than the critical value (rho=0.456). Therefore it is concluded
that there is a correlation between the ranking of both groups and the null hypothesis
should be accepted.
Table 4.13: Critical values of (rho) at various levels of probability (Naoum, 1998)
Level of Significance (P) N (number of
factors) .05 .025 .01 .005
5 .900 1.000 1.000 ---
6 .829 .886 .943 1.000
7 .714 .786 .893 .929
8 .643 .738 .833 .881
9 .600 .683 .783 .833
10 .564 .648 .746 .794
12 .506 .591 .712 .777
14 .456 .544 .645 .715
16 .425 .506 .601 .665
18 .399 .475 .564 .625
20 .377 .450 .534 .591
22 .359 .428 .508 .562
24 .343 .409 .485 .537
Statement of hypothesis testing:
Table 4.12 shows that there is a high correlation in the ranking of quality factors of
the two types of contracting companies. Hence, the null hypothesis can be accepted
concluding that the contracting companies who have an ISO certificate and the other
companies, who do not have such a certificate, do not perceive quality factors
٦٦
differently. Table 4.12 also shows that there seems to be an overall agreement by
both samples with regard to quality factors (rho=0.997).
4.2.3 One-Way ANOVA Test
One-Way ANOVA test was done to find if there is a significant difference due to the
position of the respondent who filled the questionnaire. One-Way ANOVA test is
used when there is more than one group belonging to one variable, as in our case the
groups of manager, deputy manager, project engineer and site engineer are related to
one variable which is position. The average weighted factors resulted from ranking
the sub-factors affecting quality (section 4 of the questionnaire) are used in this test.
The research question:
Do the position of the respondent affect the ranking of the quality factors?
The research hypothesis:
There is a significant difference in perception between the manager, deputy
manager, project engineer and site engineer towards ranking quality factors.
The null hypothesis:
There is no difference between the manager, deputy manager, project engineer and
site engineer towards ranking quality factors.
Statement of hypothesis testing:
The results are shown in Table 4.14. P-value is greater than 0.05 in all factors. This
means that there is no significant difference between the means of ranking of four
groups (Manager, Deputy Manger, Project Engineer and Site Engineer). The null
hypothesis can be accepted. The results show that there seems to be an overall
agreement by all the groups with regard to quality factors.
It is obvious that the position of the respondent who fills the questionnaire does not
affect the attitude towards ranking the quality factors. This may be attributed to the
٦٧
fact that all of these groups are involved in the same experience during the
construction process.
Table 4.14: One- Way ANOVA Results Item Description Sum of
Squares
df Mean
Squares
F Sig.
Project Between Groups
Within Groups
Total
.623
55.811
56.434
3
85
88
.208
.657
.316 .813
Design Between Groups
Within Groups
Total
.789
20.975
21.764
3
85
88
.263
.247
1.066 .368
Contract Between Groups
Within Groups
Total
2.108
29.957
32.065
3
85
88
.703
.352
1.994 .121
Material Between Groups
Within Groups
Total
1.148
30.923
32.071
3
85
88
.383
.364
1.052 .374
Labors Between Groups
Within Groups
Total
7.366
133.179
140.545
3
85
88
2.455
1.567
1.567 .203
Equipment Between Groups
Within Groups
Total
.842
36.904
37.746
3
85
88
.281
.434
.646 .588
Subcontractors Between Groups
Within Groups
Total
.480
29.129
29.610
3
85
88
.160
.343
.467 .706
Site Layout Between Groups
Within Groups
Total
1.325
58.775
60.100
3
85
88
.442
.691
.639 .592
Systems Between Groups
Within Groups
Total
1.067
33.67
34.739
3
85
88
.356
.396
.898 .446
Site staff Between Groups
Within Groups
Total
.319
16.572
16.890
3
85
88
.103
.195
.545 .653
٦٨
Execution Between Groups
Within Groups
Total
.312
19.462
19.774
3
85
88
.104
.229
.454 .715
Financial
Issues
Between Groups
Within Groups
Total
.137
32.111
32.247
3
85
88
.455
.378
.121 .948
Owner Between Groups
Within Groups
Total
1.787
30.236
32.022
3
85
88
.596
.356
1.674 .179
Environment Between Groups
Within Groups
Total
.526
34.471
34.997
3
85
88
.175
.406
.432 .730
.CHAPTER 5
MODEL DEVELOPMENT
There is a consensus among researchers and industry experts that one of the
principal barriers to promote improvement in construction projects is the lack of
appropriate tools for quality measurement. Through this research, a model
representing local quality factors is developed and used as a tool to measure quality
of construction projects in Gaza Strip..
A model is a physical or symbolic representation of the relevant aspects of the
reality or system, which are in concern. It is a mean of portraying the system or
reality of concern to the decision maker.
The developed model philosophy is suggested to be based upon the following:
٦٩
• Quality measurement is the trigger for quality improvement.
• The concept of quality management and improvement is changed from
controlling quality to controlling management of quality.
• Every thing falls under quality umbrella (productivity, safety…and etc.)
Different approaches were conducted to develop such a model. (Abdel-Razek, et al.,
2001) studied the factors affecting quality of construction projects in Egypt, and
developed a model based on average weighted approach based on weighting the
different factors affecting quality. (Chan and Tam, 2000) studied the factors
affecting quality of construction projects in Hong Kong. They developed a model
through applying factor analysis and multiple regression technique.
In this study, these approaches were adopted and applied on ranking data of sub-
factors affecting quality as presented in section 4 of the questionnaire. The results
are discussed in the subsequent sections and the appropriate model, which represents
the most important factors affecting quality is used as a measurement tool of quality
of construction projects in Gaza Strip.
5.1 Approach 1: The Weighted Average Approach
The sub-factors of section 4 in the questionnaire are used to calculate the average
weight of each main factor (group). The following formula was used to calculate the
average weight of each main factor.
Average Weight of each factor = (Summation of scores of sub-factor in each group)/
(Total number of factors in each group) * (Total number of respondents)
Example: The average weight of main factor “Design” = (407 + 403 + 386 + 413 +
397) / (5 * 89) = 4.50
The main factors are organized in a descending order of priority. The results are
shown in Table 5.1
٧٠
Table 5.1: Average weight of main factors
Priority Order Main Factor Average Weight
1 Site Staff 4.62
2 Design 4.50
3 Finance 4.49
4 Subcontractors 4.20
5 Material 4.11
6 Labors 4.08
7 Systems 4.03
8 Environment 3.99
9 Contract 3.91
10 Execution 3.78
11 Equipment 3.77
12 Site layout 3.73
13 Owner 3.69
14 Project 3.55
5.1.1 Model Formulation
As resulted from Table 5.1, all the fourteen main factors have significant weights,
therefore, they can be considered as main elements of the proposed model.
Therefore, the quality can be expressed in terms of the following main factors as:
Model 1 Quality = (SS + D + F + SUB + M + L + S + EN + CON + EXE + EQ + SL + OWN +
PR)*(100 / 70)
Where
- SS, D, F, SUB, M, L, S, EN, CON, EXE, EQ, SL, OWN, PR are
average weighted scores resulted from ranking Site Staff, Design, Finance,
Subcontractors, Material, Labor, Systems, Environment, Contract, Execution,
Equipment, Site layout, Owner and Project respectively.
٧١
- 70 = The Summation of maximum scores of the fourteen elements
= 14 elements * maximum score of the element (i.e. 5.0)
- 100 = The expected result of score of quality
The model developed by (Abdel-Razek, et al., 2001) which was based on average
weighted approach incorporates 10 main factors affecting quality of construction
projects in Egypt. The model can be summarized in the following:
Project Construction Quality = (D + C + M + L + E + SUB + SL + SYS + SS + EX)
*(100/50)
Where: D, C, M, L, E, SUB, SL, SYS, SS and EX are average weighted scores of
Design, Contract, Material, Labor, Equipment, Subcontractors, Site layout, Systems,
Site Staff and Execution.
In this study about factors affecting quality in construction projects in Gaza Strip, 4
more new factors were added as shown in model 1, which are Environment,
Financial issues, Owner and Project.
5.2 Approach 2: Pareto Analysis for Main Factors Affecting Quality Pareto analysis was first presented by the Italian economist V.Pareto in 1897 and later
expressed diagrammatically by the American economist M.C.Larenz in 1907 (Kume, 1995
cited in Abdel-Razek, 1998b). Both of these scholars pointed out that by far the largest share
of income or wealth is held by a very small number of people. In the field of quality control,
Juran suggested this analysis in order to classify problems of quality into the vital few and
the trivial many (Abdel-Razek, 1998b). Thus, if the vital quality improvement factors are
identified, most of the causes of poor quality could be eliminated by concentrating on these
particular factors first. In order to classify the distribution pattern of the quality factors
obtained, a Pareto analysis of the 14 main factors was carried out. The data collected of
ranking the sub-factors at Section 4 in the questionnaire are analyzed, concluding the score
and relative percent of each factor.
٧٢
The results of Pareto Analysis are shown in Table 5.2 and illustrated in Figure 5.1
and Figure 5.2. They show the 14 main factors affecting quality together with the
contribution of each factor as a score and a percentage respectively.
Table 5.2: Pareto Analysis of Quality Factors No. Factor Average
Score
Factor Weight
%
Cumulative
Weight %
1 Site Staff 411.5 8.18 8.18
2 Design 401.2 7.97 16.15
3 Finance 400.0 7.96 24.11
4 Subcontractors 374.0 7.44 31.55
5 Material 366.2 7.28 38.83
6 Labor 363.4 7.23 46.06
7 Systems 359.0 7.13 53.19
8 Environment 355.5 7.07 60.26
9 Contract 348.6 6.93 67.19
10 Execution 336.75 6.69 73.88
11 Equipment 336.0 6.68 80.56
12 Site layout 332.25 6.61 87.17
13 Owner 329.25 6.55 93.72
14 Project 316.25 6.28 100.0
Total 5029.9
F a c to rs S c o re
05 0
1 0 01 5 02 0 02 5 03 0 03 5 04 0 04 5 0
1 2 3 4 5 6 7 8 9 1 0 1 1 1 2 1 3 1 4
fa c to r n u m b e r
fact
or a
vera
ge
scor
e
F a c to r s S c o r e
٧٣
Figure 5.1: Quality Factors, Voting and Scoring Results
Figure 5.2: Pareto Analysis of Quality Factors
The results of the Pareto Analysis show that the first ten factors contribute to about
74% of the weight of all the factors as shown in Table 5.2 and illustrated in Figure
5.2. These ten factors can be considered as the most important factors affecting
quality of a construction project. Therefore, these factors will be taken as the base
for the proposed model.
Model 2
Quality = (SS + D + F + SUB + M + L + S + EN + CON + EXE) * (100/50)
Where
0
1
2
3
4
5
6
7
8
9
f1 f2 f3 f4 f5 f6 f7 f8 f9 f10 f11 f12 f13 f14
factor number
% fa
ctor
wei
ght
0
20
40
60
80
100
120
% c
umul
ativ
e w
eigh
t
Factor's Weight (%)Cumulative Weight (%)
٧٤
- SS, D, F, SUB, M, L, S, EN, CON, EXE are average weighted scores
resulted from ranking Site Staff, Design, Financial Issues, Subcontractors,
Material, Labor, Environment, Contract and Execution.
- 50 = the summation of maximum scores of the ten elements
= 10 elements * maximum score of the element (i.e. 5.0)
- 100 = The expected result of score of quality.
5.3 Approach 3 : Factor Analysis of Sub-factors Affecting quality
Factor Analysis is a technique for finding a small number of underlying dimensions
from among a large number of variables (West, 1991). This technique was applied
in this study to identify a relatively small number of factors that can be used to
represent relationships among those 60 sets of independent variables (sub-factors
affecting quality presented in section 4 of the questionnaire).
There are generally two steps to factor analysis:
1. The extraction of the factors; and
2. The rotation of the factors.
The former finds out how many dimensions there are, and the latter obtains a clearer
picture of what these dimensions (or factors) represent.
٧٥
5.3.1 Factor Extraction
The 60 Sub-Factors affecting quality of a construction project were assumed to be
independent variables. Principal component analysis was used to identify the
underlying factors. To determine how many factors will be needed to represent the
data, the percentage of total variance explained by each is examined. The total
variance is the sum of the variance of each variable. Since there are 60 variables and
each is standardized to have a variance of 1, the total variance is 60.
Table 5.3 contains the initial statistics for each factor. The full names of the
variables can be found in Appendix (D). The total variance explained by each factor
is listed in the column labeled “Eigen value”. The next column contains the
percentage of the total variance attributable to each factor. For example, factor 2 has
a variance of 4.467, which is 7.446 percent of the total variance of 60. The last
column, the cumulative percentage, indicates the percentage of variance attributable
to that factor and those that precedes it in the table. The first two columns provide
information about the variables, while the last four columns describe the factors.
Several procedures have been proposed for determining the number of factors to use
in a model. One criterion suggests that only the factors that account for variance
greater than 1 (Eigen value greater than 1) should be included (Chan and Tam, 2000).
Another criterion is called the Scree plot test illustrated in Figure 5.3. Both of the
two criteria will be used in this study.
Table 5.3, shows that almost 78 percent of the total variance is attributed to the first
18 factors where each factor have an Eigen value greater than 1. The remaining 42
factors together account for only 21.8 percent of the variance. Thus a model with 18
factors should be considered adequate to represent the data.
٧٦
Figure 5.3 is called a Scree plot of the total variance associated with each factor. It
plots the new factors as the X-axis and the corresponding eigen values as the Y-axis.
As one moves to the right, towards later factor, the Eigen values drop. The plot
shows a distinct break between the steep slope of the large factors and the gradual
trailing off of the rest of the factors. This gradual trailing off is called the scree
because it resembles the rubble that forms at the foot of a mountain. Experimental
evidence indicates that the scree begins at the kth factor, where k is the true number
of factors (Chan and Tam, 2000).
From the Scree Plot, Figure 5.3, it again shows that 18 factor model should be
sufficient for the research model.
Table 5.3: Initial statistics for the 60 variables (sub-factors affecting quality)
Variable
(sub-factor) Communality New Factor Eigen value Percentage
variance
Cumulative
percentage
typeproj 1.000 1 13.047 21.745 21.745
projloc 1.000 2 4.467 7.446 29.191
projacce 1.000 3 3.655 5.592 34.782
projper 1.000 4 2.858 4.763 39.545
desdoc 1.000 5 2.542 4.237 43.783
drawings 1.000 6 2.409 4.016 47.798
codes 1.000 7 2.233 3.721 51.519
specific 1.000 8 2.087 3.478 54.997
billquan 1.000 9 1.911 3.185 58.182
cooperat 1.000 10 1.799 2.999 61.182
prevrel 1.000 11 1.691 2.818 64.000
contcond 1.000 12 1.466 2.443 66.443
stancont 1.000 13 1.404 2.340 68.783
awardsys 1.000 14 1.234 2.056 70.839
matesys 1.000 15 1.186 1.977 72.817
contsupp 1.000 16 1.122 1.870 74.687
availmat 1.000 17 1.104 1.840 76.527
٧٧
storsys 1.000 18 1.012 1.687 78.214
matmonop 1.000 19 .899 1.499 79.713
laborsys 1.000 20 .846 1.410 81.123
laborexp 1.000 21 .812 1.353 82.727
motivsys 1.000 22 .751 1.251 83.727
labtrain 1.000 23 .711 1.185 84.912
labfinan 1.000 24 .662 1.103 86.015
equavail 1.000 25 .641 1.069 87.083
equisys 1.000 26 .597 .996 88.079
equiprod 1.000 27 .577 .962 89.041
equiutil 1.000 28 .565 .941 89.982
equimain 1.000 29 .485 .808 90.791
selecsub 1.000 30 .466 .777 91.568
subgen 1.000 31 .446 .744 92.312
subperf 1.000 32 .405 .675 92.986
subcont 1.000 33 .355 .591 93.577
sitelarg 1.000 34 .344 .573 94.151
siteorg 1.000 35 .338 .563 94.713
sitestor 1.000 36 .314 .523 95.236
siteclean 1.000 37 .283 .472 95.709
infotech 1.000 38 .262 .437 96.146
qualassu 1.000 39 .247 .411 96.557
timesche 1.000 40 .217 .362 96.919
costsys 1.000 41 .198 .329 97.249
safeprog 1.000 42 .178 .296 97.545
supecon 1.000 43 .160 .267 97.812
understa 1.000 44 .156 .260 98.072
supexp 1.000 45 .148 .246 98.318
contexp 1.000 46 .131 .218 98.536
supersys 1.000 47 .126 .209 98.746
testfin 1.000 48 .120 .201 98.946
٧٨
receproc 1.000 49 .101 .168 99.114
shopdraw 1.000 50 8.715E-02 .145 99.259
cashflow 1.000 51 7.470E-02 .124 99.384
delayint 1.000 52 7.243E-02 .121 99.505
ownernat 1.000 53 6.505E-02 .108 99.613
ownerdec 1.000 54 5.659E-02 9.432E-02 99.707
ownercon 1.000 55 5.477E-02 9.128E-02 99.799
ownerqua 1.000 56 3.492E-02 5.820E-02 99.857
econenvi 1.000 57 3.109E-02 5.181E-02 99.909
politenv 1.000 58 2.466E-02 4.110E-02 99.950
closure 1.000 59 1.808E-02 3.013E-02 99.980
consindu 1.000 60 1.213E-02 2.022E-02 100.000
Scree Plot
١ ٤ ٧ ١٠ ١٣ ١٦ ١٩ ٢٢ ٢٥ ٢٨ ٣١ ٣٤ ٣٧ ٤٠ ٤٣ ٤٦ ٤٩ ٥٢ ٥٥ ٥٨
Eigenvalue
14
12
10
8
6
4
٢
0
٧٩
Figure 5.3: Factor Scree Plot
5.3.2 Factor Rotation
Once a set of common factors has been identified, there remains the question of how
the individual variables (sub-factors) relate to those common factors. A Varimax
rotation method was used in this study to explore the relationship of the individual
variables (sub-factors) to these common factors. It is an orthogonal rotation of the
factor axis to maximize the variance of the squared loadings of a factor (column) on
all the variables (rows) in a factor matrix, which has the effect of differentiating the
original variables by extracted factor. That is, it minimizes the number of variables,
which have high loadings on any given factor. Each factor will tend to have either
large or small loadings of particular variables on it. A varimax solution yields results
which make it easy as possible to identify each variable with a single factor. This is
the most common rotation option.
Table 5.4 shows the factor rotation results indicating the new factors and their
elements related to each factor. It also shows the strength of correlation between
new factor and their variables.
Table 5.4: Factor Rotation Results Item Factor 1 Factor 2 Factor 3 Factor 4 Factor 5
• Site layout is organized
well.
• Site layout is large and
suitable for labors movement.
• Site layout has storage
areas for materials.
.836
.816
.782
• Income level and wages of
labors.
.767
٨٠
• Skill and experience of
supervision staff.
• Understanding of contract
administration by supervision
staff.
• Skill and experience of
contractors’ staff.
.757
.732
.728
• Completeness and
consistency of design documents.
• Drawings are prepared in
full details.
.752
.686
• Materials storage and
handling system.
• Cooperation between
contractor and material suppliers.
• Using a comprehensive
material management system.
.814
.757
.708
Item Factor 6 Factor 7 Factor 8 Factor 9 Factor 10
• Implementation of quality
control and assurance system.
• Using computer software
and applications.
.738
.659
• Preparing and using
shopdrawing.
.726
• Equipment management
system.
.657
• The non-delay of interim payments
• The amount of
contractor’s cash flow.
.844
.684
• Stability of political
environment.
• Closure of Gaza Strip.
.785
.778
Item Factor 11 Factor 12 Factor 13 Factor 14 Factor 15
• Labor experience .771
٨١
• Clear procedure for
accepting performed activities.
.840
• Owner’s contribution to
design
.831
• Using a comprehensive
execution system
.764
• Owner’s quick response (no
delays in making decisions)
.879
Item Factor 16 Factor 17 Factor 18
• Cooperation between
supervision and contractor’s staff
.781
• Type of awarding system. .778
• Labors management system. .832
As a result from the factor analysis technique, the 60 independent variables (sub-
factors) were reduced to 18 new factors, which can be renamed in the following
Table 5.5.
Table 5.5: New Factors affecting Quality
Factor Name of Factor
F1 Characteristics of site layout
٨٢
F2 Income level and wages of labors
F3 Characteristics of site staff
F4 Characteristics of Design documents
F5 Materials Management System
F6 Control Systems
F7 Preparing and using shopdrawing
F8 Equipment Management System
F9 Financial Management System
F10 Political Environment
F11 Labor experience
F12 Clear Procedures for accepting performed activities
F13 Owner’s contribution to design
F14 Integrated Management Execution System
F15 Owner’s quick response for taking decisions
F16 Cooperation between supervision and contractor’s staff
F17 Type of awarding system
F18 Labor Management system
A revised research model, consisting of these 18 factors, is then produced to replace
the original which has 60 sub-factors affecting quality as shown in Figure (3.2).
Model 3, which represents these new factors, is shown in Figure 5.4
٨٣
5.4 Approach 4: Stepwise Multiple Regression Analysis
In this approach, the stepwise multiple regression was applied on the 18 new factors
resulted from the factor analysis. The aim of this method is to define the most
important factors affecting quality and the contribution of these factors to the overall
quality of a construction project.
٨٤
A Stepwise model-building technique for regression designs with a single variable
has the basic procedures which involve (1) identifying an initial model, (2)
iteratively “Stepping”, that is, repeatedly altering the model at the previous step by
adding or removing a predictor variable in accordance with the “Stepping criteria”,
and (3) terminating the search when stepping is no longer possible given the
stepping criteria, or when a specified maximum number of steps has been reached.
The following topics provide details on the use of stepwise model-building
procedures.
• The Initial Model in Stepwise Regression
The initial model is designated the model at step (0). The initial model always
includes the regression intercept (Unless the no intercept option has been specified).
• The Forward Entry Method
The forward entry method is a simple model-building procedure. At each step after
step (0), the entry statistics is computed for each eligible for entry in the model. If no
effect has a value for model entry, then stepping is terminated, otherwise the effect
with the largest value on the entry statistic is entered into the model. Stepping is also
terminated if the maximum number of steps is reached. (StatSoft, 2002)
A primary purpose of this study was to develop a model representing the
relationship between the quality and its factors. As shown in Figure 5.4, the 18
factors described in Section 5.3 were utilized as independent variables to determine
their usefulness for predicting changes in the dependent variable, which is quality. A
total of 18 factors were measured for 89 cases and stepwise multiple regression
analysis was applied to determine the relationships of these underlying factors with
quality performance. A summary of the regression results can be seen in Table 5.6.
Table 5.6: Stepwise Multiple Regression Analysis Results Model R R 2 F Significant
1 .669 a .447 70.337 .000 *
2 .860 b .739 121.973 .000 *
3 .905 c .818 127.693 .000 *
4 .929 d .864 133.087 .000 *
5 .951 e .904 156.178 .000 *
٨٥
6 .963 f .927 174.355 .000 *
7 .971 g .943 193.036 .000 *
8 .977 h .955 212.635 .000 *
9 .981 i .963 227.868 .000 *
10 .985 j .969 245.794 .000 *
11 .988 k .976 286.352 .000 *
12 .991 l .981 331.266 .000 *
13 .993 m .985 385.388 .000 *
14 .994 n .989 460.580 .000 *
15 .996 o .993 665.898 .000 *
16 .998 p .996 1089.832 .000 *
17 .999 q .998 2162.180 .000 *
18 1.000 r 1.000 . .
* P less than 0.05
a. Predictors: (constant), F1
b. Predictors: (constant), F1, F18
c. Predictors: (constant), F1, F18, F10
d. Predictors: (constant), F1, F18, F10, F5
e. Predictors: (constant), F1, F18, F10, F5, F3
f. Predictors: (constant), F1, F18, F10, F5, F3, F6
g. Predictors: (constant), F1, F18, F10, F5, F3, F6, F4
h. Predictors: (constant), F1, F18, F10, F5, F3, F6, F4, F8
i. Predictors: (constant), F1, F18, F10, F5, F3, F6, F4, F8, F17
j. Predictors: (constant), F1, F18, F10, F5, F3, F6, F4, F8, F17, F15
k. Predictors: (constant), F1, F18, F10, F5, F3, F6, F4, F8, F17, F15, F14
l. Predictors: (constant), F1, F18, F10, F5, F3, F6, F4, F8,F17,F15, F14, F9
m. Predictors: (constant), F1, F18, F10, F5, F3, F6, F4, F8, F17, F15, F14, F9, F12
n. Predictors: (constant), F1, F18, F10, F5, F3, F6, F4, F8, F17, F15, F14, F9, F12,
F13
o. Predictors: (constant), F1, F18, F10, F5, F3, F6, F4, F8, F17, F15, F14, F9, F12,
F13, F2
p. Predictors: (constant), F1, F18, F10, F5, F3, F6, F4, F8, F17, F15, F14, F9, F12,
F13, F2,F7
٨٦
q. Predictors: (constant), F1, F18, F10, F5, F3, F6, F4, F8, F17, F15, F14, F9, F12,
F13, F2, F7, F11
r. Predictors: (constant), F1, F18, F10, F5, F3, F6, F4, F8, F17, F15, F14, F9, F12,
F13, F2, F7, F11, F16
Table 5.6 shows 18 models, which include different factors. To choose the
appropriate model, the value of R2 is used as a guide. As R2 is the percent of
variance in the independent variables to variance of the dependent variable, the
value of R2 equal 0.981 will be taken as indication of the appropriate model. This
means that any change in the independent variables represent 98.1% of change in the
dependent variable, which is quality.
Other values of R2 could be used for choosing other models, but the value of R2
equal 0.981 is sufficient to represent the most important factors affecting quality.
Also it will narrow the factors used in the proposed model to 12 factors and this will
make the model easy to use. Therefore, model number 12 with R2 equal 0.981 was
chosen. Coefficients of the different factors and results of the multiple regression are
found in Appendix (E).
Model 4
Quality = (13.67 + 1.35 F1 + 1.21 F3 + 1.28 F4 + 1.02 F5 +1.18 F6 + 1.29 F8
+ 0.75 F9 + 1.09 F10 + 0.96 F14 + 1.14 F15 + 0.96 F17 + 1.06 F18) * (100/80.12)
Where
- F1, F3, F4, F5, F6, F8, F9, F10, F14, F15, F17, F18 are average weighted
scores resulted from collecting the ranking scores of the factors explained as the
following:
F1: Characteristics of site layout.
F3: Characteristics of site staff.
F4: Characteristics design documents.
F5: Material Management System.
F6: Control Systems.
F8: Equipment Management System.
F9: Financial Management System.
٨٧
F10: Political Environment.
F14: Integrated Management Execution System.
F15: Owner’s Quick Response for Taking Decisions.
F17: Type of awarding system.
F18: Labor Management System.
- 80.12 = the summation of the formula if each factor has the maximum
score, which is 5.
- 100 = The expected result of quality score.
Multiple regression analysis has identified that 12 out of the 18 factors resulted from
factor analysis were significantly associated with the quality performance.
Therefore, quality can be increased by improvement of characteristics of site layout,
hiring skilled and experienced management staff, improving design documents,
using different management systems, following financial management system,
increasing the emphasis of owner on making decisions, using management
execution system, and improving the income level and wages of labors.
(Chan and Tam, 2000) predicted, in their study on factors affecting quality of
construction projects in Hong Kong, four factors that have the most effect on
quality. Their model can be summarized in the following:
Quality = 5.2 + 0.5 MAN_ACT + 0.08 EFF_CON – 0.30 CLI_QUA – 0.38 CLI_TIME
Where:
MAN_ACT: Project Management Action
EFF_CON: Effectiveness of construction leader
CLI_QUA: Client emphasis on quality
CLI_TIME: Clients emphasis on time
Chan research findings, as concluded from this study, support the importance of
using different management systems and the role of owner toward improving
quality. Also it emphasizes the role of the team leader who has a significant impact
on project quality.
5.5 Choosing the Appropriate Model
٨٨
A good theory is the end result of a winnowing process. It is started with a
comprehensive model that includes all conceivable and testable influences on the
phenomena under investigation. Using different statistical techniques, a simple
model can be reached which is considered as the best explanation for the phenomena
under investigation. Simple models were preferred for practical reasons. They are
easier to put for testing and are less costly to put in practice.
For these reasons and because model 1, 2 and 3 are in general form, model 4
resulted from Stepwise Multiple Regression technique, is recommended as the
appropriate model to measure quality of a construction building project during
construction phase. Model 4 represents the most important factors resulted in models
1, 2, and 3 and asserted the results of these models. Also, model 4 has coefficients of
these factors, which represents the magnitude of sensitivity of change of each factor
towards change of quality.
Quality = (13.67 + 1.35 F1 + 1.21 F3 + 1.28 F4 + 1.02 F5 +1.18 F6 + 1.29 F8
+ 0.75 F9 + 1.09 F10 + 0.96 F14 + 1.14 F15 + 0.96 F17 + 1.06 F18) * (100/80.12)
5.6 Model Application
In order to make Model 4 more practical and easy to use as a measuring tool of
quality of a construction project, two forms are developed. In the first form as shown
in Figure 5.5, a Construction Manager or a Project Engineer will be asked to rank
the degree of their agreement on different elements resulted from factor rotation as
shown in Table 5.4 and related to the factors affecting quality in their specific
project.
The second form was developed in Excel sheet as shown in Figure 5.6. It
incorporates the data collected from the first form. The first column is used for
factor elements, the second for presenting the score of each element, the third
column assigns the main factor as resulted from the multiple regression analysis, and
the fourth column represents the computation of the average weight of each factor
٨٩
depending on the scores of its elements. The last row in the worksheet assigns the
value of quality as computed by Model 4 for a specific project out of 100.
Figure 5.5: Form 1, worksheet for measuring quality in construction projects
Project Name: ………………………………………………………………………. Contractor : ……………………………………………………………………….
Please identify (carefully) the degree of Agreement of each of the following factors in your construction project. 5 = Strongly agree 4 = Agree 3 = Neither agree nor disagree
٩٠
2 = Disagree 1 = Strongly disagree
Degree of Agreement
No. Quality Factor
5 4 3 2 1 1 Site layout of your project is large and easy for movement
2 Site layout is clean and free from debris or obstacles
3 Site layout has storage areas
4 Consulting supervision staff are skilled and have wide experience
5 Contractor’s staff are skilled and have wide experience
6 Supervision staff understand contract conditions
7 Contractor’s staff understand contract conditions
8 Completeness and consistency of design documents
9 Drawings are clear and have full details
10 Materials are supplied according to standard procedure
11 There is a cooperation between the contractor and material suppliers
12 Storage management system is used
13 Testing of different products are used to control quality
14 Using computer software and applications
15 There is a management system for using equipments
16 There is plenty of cash flow during the construction
17 Interim payments are not delaying
18 Your project is not strongly affected by political environment
19 Your project is not strongly affected by closure of Gaza Strip
20 There is a clear procedure for accepting final works
21 Coordination between parties performing the work
22 The owner takes decisions in proper time
23 Your project is not awarded according to lowest price
method
24 There is a management system for controlling labor work
٩١
5.7 Model Verification
Model verification is undertaken to ensure the soundness and usefulness of the
model. Two construction projects were taken to test Model 4. These projects are two
UNRWA new schools. One of them is under construction and the other has just been
completed. Two project managers were given the worksheet (Form 1), explained in
٩٢
Figure 5.5 to define their degree of agreement of the different factors assigned in the
model.
The First Project:
Name of the project: Khan Younis Preparatory Girls School
Period of the project: 48 weeks
Total sum: $ 584,106.30
Type of contract: Unit price
Designer: UNRWA Design Unit
Supervision: UNRWA Construction Division
Contractor: UNRWA Contracting Section
Status of the Project: Completed
The data collected from Form 1 is filled in the Excel worksheet as shown in Figure
5.7. The computed project quality score equals 83 %.
٩٣
The Second Project:
Name of the project: Farabi Elementary School at Bani Suhaila
Period of the project: 48 weeks
Total sum: $ 475,072.50
Type of contract: Unit price
٩٤
Designer: UNRWA Design Unit
Supervision: UNRWA Construction Division
Contractor: Golden Sand Company, Gaza
Status of the Project: Under Construction
The final score of quality is shown in the Excel sheet in Figure 5.8, which equals
77%.
The results demonstrate the applicability of the developed model in measuring
quality of different construction projects. This model can be used at different stages
of construction. It also helps in identifying the weak points that affect in lowering
project quality score. Therefore, it helps project mangers to take actions toward
improving these low score areas and hence improving the overall project quality.
٩٥
CHAPTER 6
CONCLUSION AND RECOMMENDATION
6.1 Conclusion
٩٦
Review of the previous methods of quality measurement clarified that the
construction projects in Gaza Strip are in need to a local quality measurement model
that specifies the prevailing conditions.
The Nominal Group Technique was carried out to define the factors affecting quality
of a construction project during construction phase. Combining the results of NGT
with other internationally developed models, 14 main factors and 60 sub- factors
affecting quality were determined. Based on ranking the sub-factors affecting
quality, the weights of the main factors were determined. The weighting process
showed that site staff, design, and financial issues are the most important elements,
while the least important quality element is the nature of project.
Four models were developed through four approaches:
• Model 1: through weighted average approach, the weights of sub-factors
were used to determine the weight of each main factor, the model developed is
as follows:
Quality = (SS+D+F+SUB+M+L+S+EN+CON+EXE+EQ+SL+OWN+PR)* (100/70)
• Model 2: Through Pareto Analysis, the important main factors were
determined. Site Staff, Design, Financial Issues, Subcontractors, Materials,
Labors, Systems, Environment, Contract and Execution contribute 74% of the
weight of all factors. The model is represented by the following:
Quality = (SS+D+F+SUB+M+L+S+EN+CON+EXE)*(100/50)
• Model 3: Using Factor Analysis Technique on the sub-factors affecting
quality, the 60 sub-factors were reduced to 18 categories (Factors) affecting
quality. The new factors renamed as following:
1. F1: Characteristics of site layout
2. F2: Income level and wages of labors
3. F3: Characteristics of site staff
4. F4: Characteristics of design documents
5. F5: Materials management system
6. F6: Control systems
7. F7: Preparing and using shopdrawing
٩٧
8. F8: Equipment management system
9. F9: Financial Management System
10. F10: Political environment
11. F11: Labor experience
12. F12: Clear procedures for accepting performed activities
13. F13: Owner’s contribution to design
14. F14: Integrated Management Execution System
15. F15: Owner’s quick response for taking decisions
16. F16: Cooperation between supervision and contractor’s staff
17. F17: Type of awarding system
18. F18: Labor management system
• Model 4: Through Stepwise Multiple Regression, the factors produced in
Model 3 were utilized as independent variables to determine their usefulness for
predicting changes in the dependent variable which is Quality. The results of the
Stepwise Multiple Regression were used in forming Model 4.
Quality = (13.67 + 1.35 F1 + 1.21 F3 + 1.28 F4 + 1.02 F5 +1.18 F6 + 1.29 F8
+ 0.75 F9 + 1.09 F10 + 0.96 F14 + 1.14 F15 + 0.96 F17 + 1.06 F18) * (100/80.12)
As the first three models were in general forms, Model 4 was considered as the most
useful for predicting the quality of a construction project.
In order to make Model 4 more practical and easy to use, the elements of the model
were incorporated in an Excel Sheet. This sheet makes it possible for a project
manager to input the weights of the elements and the degree of quality will then be
computed directly.
The model was verified through testing on two construction projects. The results
show that it is easy to use and useful as a tool to measure the quality of a
construction building project.
6.2 Recommendation
1. It is recommended to use the developed predictive model (model 4) to measure
project quality performance. Project managers can use this model to assess the
quality level of a construction project. Assessments of likely project outcomes can
٩٨
be ascertained during construction and any necessary correction actions can be
initiated.
2. It is important that each contracting or consulting firm to select or design its own
definition for quality, so that it can form a common language of quality. This
definition should be clear and understood by everyone in the firm. Once speaking
the same language, quality can be measured and managed effectively. The quality
elements to be understood clearly are:
♦ Definition of quality is how to reach the client satisfaction.
♦ Quality is a target for every one in the company.
♦ It is a team work and a continuous improvement process.
♦ Quality is the responsibility of everyone and not of Top Management
only.
3. It is important that the contracting or consulting firms develop a quality
management system to meet the requirements of the international quality standards.
This quality system should contain three levels of documentation, which are
hierarchical in nature:
• Quality Manual: provides a concise summary of the quality management policy
and quality system.
• Procedures Manual: describes the system functions.
• Work instructions: contains specifications and detailed methods.
4. Achieving the quality improvement needs the cooperation of all the parties
involved in the construction industry. Owners, designers, supervision staff, and
contractors should exert concerted efforts in order to establish and disseminate
quality awareness.
5. It is recommended to keep the site layout cleaned and organized well. This will
facilitate the construction process and improve the output quality.
6. Characteristics of site staff (both supervision and contractor) play a pivot role in
affecting the overall quality of a construction project. The staff must be familiar with
the construction materials and techniques that will be used in the project. It is
important to involve them in training courses, since they could have a significant
role in improvements of most work areas.
٩٩
7. Drawings, specifications, bill of quantities and design documents received from
the designer affect the quality of the construction project. Drawings and bill of
quantities are the only documents given to the contractor that show the design
concept, size and scope of the job. Therefore, it is critical that the drawings, bill of
quantities and specifications be clear, concise and uniform. Local standards should
be developed to ensure minimum quality requirements and procedure to measure
them.
8. It is recommended for the contracting firms to develop its own overall
management system, that contains materials management system, equipment
management system and labors management system. These systems will ensure that
most quality elements be achieved.
9. The Owners need to increase their level of coordination and input in the several
stages of the construction project. Contribution of Owners in the design process and
making the right decisions in the proper time will improve the quality of
construction projects.
10. It is recommended that Owners who seek high quality should not award
contracts to the lowest bidder whose price is lower than the project fair estimate, as
many projects were delayed and suffer from quality problems especially when these
projects were awarded by open tendering system. However, lower price bidder
system can be used if there is a short list of prequalified quality contractors.
REFERENCES
١٠٠
Abdel-Razek, R.H., El-Dosouky, A.I. and Solaiman, A.M. (2001), “A Proposed
Method to Measure Quality of the Construction Project”, International Exhibition
Conference for Building & Construction, Egypt.
Abdel-Razek, R.H. (1998a), “Factors Affecting Construction Quality in Egypt:
identification and relative importance”, Journal of Engineering Construction and
Architectural Management, Vol.5, PP.220-227.
Abdel-Razek, R.H. (1998b), “Quality Important in Egypt: Methodology and
Implementation”, Journal of Construction Engineering and Management, Vol.124,
No.5.
Davis, K., Ledbetter, W.B., and Burati, J. (1989),”Measuring Design and
Construction Quality Costs” Journal of Construction Engineering and Management,
Vol.115, No.3.
Ashford, J.L. (1989), “Management of Quality in Construction”, McGraw-Hill.
Barrett, P. (2000), “Systems and Relationship for Construction Quality”,
International Journal of Quality & Reliability Management, Vol.17 No. 4/5, PP.377-392.
Barrie, D.S. and Paulson, B.C (1992), “Professional Construction Management”,
McGraw-Hill.
Chan, A.P. and Tam, C.M. (2000), “Factors Affecting Quality of Building Projects
in Hong Kong”, International Journal of Quality & Reliability Management, Vol.17
No. 4/5, PP.423-441.
Creative Research System (2001), “Sample Size Formulas”,
http//www.surveysystem.com/ssformu.htm.
El-Sawah,H. (1998),”Quality Management Practices in the Egyptian Construction
Industry”, International Exhibition Conference for Building & Construction, Egypt.
١٠١
Evans,J. and Lindsay,W. (1992), “Management and Control of Quality”, McGraw-
Hill.
Fellows, R. and Liu, A. (1997), “Research Methods for Construction”, Blackwell
Science Ltd.
Harris, F. and McCaffer (1995), ”Modern Construction Management”, Blackwell
science.
Juran, J.M and Gyrna, F.M. (1999), “Quality Planning and Analysis”, McGraw-
Hill.
Kothari, C.R. (1982), “An Introduction to Operation Research”, Kothari.
Low, S.P. and Peh, K.W. (1996), “A Framework for Implementing TQM in
Construction”, The TQM Magazine, Vol. 8, No.5, PP.39-46..
McCabe,S. (1998), “Quality Improvement Techniques in Construction”, Addison
Wesley Longman Limited.
Nee, P.A. (1996), “ISO 9000 in Construction”, John Willy & Sons, Inc.
Olomalaiye, P., Jayawardane, A. (1998), “Construction Productivity Management”,
Addison Wesley Longman.
Palestinian Central Bureau of Statistics (2000), “Existing Buildings Survey-
Overview”, http://www.pcbs.org/english/construct/exi-over.htm.
Project Management Institute (2000), “A Guide to the Project Management Body of
Knowledge” ,http://www.pmi.org/info/pp-standardsexcerpts.asp
١٠٢
Pyzdek, T. and Berger, R.W (1996), “Quality Engineering Handbook”, Tata
McGraw-Hill.
StatSoft (2002), “General Regression Models (GRM)”,
http:/www.statsoftinc.com/textbook/stgsr.htm.
Stevens, J.D., Glagola, C. and Ledbetter, W.B. (1994), “Quality-Measurement
Matrix”, Journal of Management in Engineering, Vol.10, No.6, PP. 7784-7796.
Stevens, J.D. (1996), “Blueprint for Measuring Project Quality”, Journal of
Management in Engineering, Vol. 12,No. 2, PP.10141-10159.
Taha, H.A. (1989), “Operation Research”, McGraw-Hill.
Tan, R.R. and Lu,Y.G. (1995), “On the Quality of Construction Engineering Design
Project: Criteria and Impacting Factors”, International Journal of Quality
&Reliability Management. Vol.12, No.5, PP. 18-37.
Trigunorsyah, B. (2002), “Implementing Constructability Improvement into
Indonesian Construction Industry”, http://www.civag.unimelb.edu.au/btriguna.
Willis, T.H. (1996), “A quality Performance Management System for Industrial
Construction Engineering Projects”, International Journal of Quality &Reliability
Management. Vol.13, No.9, PP. 38-48.
APPENDIX A NOMINAL GROUP TECHNIQUE SESSION
106
Invitation Letter
الرحيم بسم اهللا الرمحن
--------------------------/السيد
العوامل املؤثرة يف اجلودة يف مـشاريع اإلنـشاءات " أنتم مدعوون حلضور ورشة عمل بعنوان " حممد عصام "وذلك كمتطلب للدراسة التكميلية اليت يقوم ا الطالب " خالل مرحلة التشييد
. املاجستري يف إدارة املشاريععامر لنيل درجةومن املهم التنويه أن موضوع اجلودة يف صناعة اإلنشاءات هو من الدراسات احلديثة اليت يـتم التعرض هلا يف هذا اال، ولذلك مت دعوة جمموعة من أساتذة اجلامعة اإلسـالمية و املكاتـب
مجاع حول ماهية العوامل اليت تؤثر يف االستشارية واملقاولني اخلرباء يف هذا اال للوصول إىل إ .اجلودة يف مشاريع اإلنشاءات خالل مرحلة التشييد يف قطاع غزة
وكذلك الوصول من خالل الدراسة إىل منوذج حلساب درجة اجلودة يف مشاريع اإلنـشاءات .ستخدم شركات املقاوالت واملكاتب االستشارية وامللّاك بشكل فعال ومباشر واليت
الساعة الثالثـة عـصرا يف قاعـة --------- املوافق--------قاء يوم سيكون الل .اجلامعة اإلسالمية / مبىن القدس K219 ورشات العمل
.حضوركم دعم للمسرية األكادميية . وتقبلوا فائق الشكر والتقدير
رفعت رستم. د
مشرف البحث
. برنامج ورشة العمل حسب اجلدول املرفق : مالحظة
APPENDIX A NOMINAL GROUP TECHNIQUE SESSION
106
Workshop Time Schedule:
1. Project Presentation. ……………………………………(20 min.)
2. Phase one ( Silent Generation)…………………………(10 min.)
3. Phase two ( Group discussion)………………………….(20 min.)
4. Break…………………………………………………….(20 min)
5. Phase three (Presentation of group discussion results)…(15 min.)
6. Phase four ( Open discussion)…………………………..(20 min.)
7. Phase five (Voting and Ranking)………………………..(15 min.)
APPENDIX A NOMINAL GROUP TECHNIQUE SESSION
106
Sheet No.1
Individual Silent Generation State all the factors that you think will affect the quality of construction projects during construction phase. 1………………………………………………………………. 2………………………………………………………………. 3………………………………………………………………. 4……………………………………………………………… 5……………………………………………………………… 6……………………………………………………………… 7……………………………………………………………… 8……………………………………………………………… 9……………………………………………………………… 10……………………………………………………………. 11……………………………………………………………. 12……………………………………………………………. 13…………………………………………………………….
APPENDIX A NOMINAL GROUP TECHNIQUE SESSION
106
Sheet No. 2
Group Discussion
Each group specifies the factors affecting quality of construction projects during construction phase in Gaza Strip. 1……………………………………………………………. 2……………………………………………………………. 3…………………………………………………………… 4…………………………………………………………… 5…………………………………………………………… 6…………………………………………………………… 7…………………………………………………………… 8…………………………………………………………… 9…………………………………………………………… 10………………………………………………………….. 11…………………………………………………………. 12…………………………………………………………. 13………………………………………………………….
APPENDIX A NOMINAL GROUP TECHNIQUE SESSION
106
Sheet No. 3
Voting and Ranking Please identify (carefully) the degree of importance of factors affecting quality of construction projects. Very important=5 Important=4 Medium important=3 Low important=2 Very low important=1
Rate Factor No. 1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
APPENDIX B THE QUESTIONNAIRE
Civil Engineering Department
Questionnaire for collecting weights of Factors Affecting Quality of the Building Construction Projects
During Construction Phase in Gaza Strip
In fulfillment of MSC Thesis Requirement
Researcher:”Moh’d Issam" Amer
Supervised By Dr. Rifat Rustum
June, 2002
108
APPENDIX B THE QUESTIONNAIRE Factors affecting quality in construction projects Supervisor: Dr. Rifat Rustum
___________________________________________ _________________________________________ Student :Moh’d Issam Amer
١٠٩ S
Introduction Dear sir, --------------------------------------------------------------------------- Improving quality of construction projects is responsibility of all project stakeholders, i.e. owners, designers and contractors. The aim of this survey is to investigate the understandings of construction project contractors and consultants about factors quality in construction project during construction phase.
یرمي ھذا االستبیان . المالك والمصمم والمقاول، دتحسین الجودة في مشاریع اإلنشاءات ھي مسؤولیة كل األطراف المشاركة في عملیة التشیی .دیم العوامل المؤثرة في الجودة في مشاریع اإلنشاءات أثناء عملیة التشیییلتق
This questionnaire is required to be filled with exact relevant facts as much as possible.
یطلب ملئ ھذا االستبیان بالحقائق المناسبة والدقیقة قدر اإلمكان All data included in this questionnaire will be used only for academic research and will be strictly confidential.
.خدم فقط بغرض البحث العلمي وسوف یتم المحافظة على سریتھاجمیع المعلومات في ھذا االستبیان سوف تست After all questionnaires are collected and analyzed, interested participants of this study will be given feedback on the overall research results.
.یان بالنتائج المستخلصة بعد إنھاء الدراسةسوف یتم إحاطة جمیع المھتمین المشاركین في ھذا االستب
APPENDIX B THE QUESTIONNAIRE Factors affecting quality in construction projects Supervisor: Dr. Rifat Rustum
___________________________________________ _________________________________________ Student :Moh’d Issam Amer
١١٠ S
Section I: Company profile السیرة الذاتیة للشركة Please cross the appropriate response. من فضلك اختار اإلجابة المناسبة
1. Please classify your organization. نوع المؤسسة
Contractor مقاول Consultant شركة استشاریة
2. Year of establishment. سنة التأسیس ………………………………………………………….
3. Class of classification. (contracting companies) شركات المقاوالت(درجة التصنیف ( First class (A) أ(جة أولىدر ( First class (b) ب(درجة أولى ( Second class درجة ثانیة Third class درجة ثالثة
4. Title of position of respondent المركز اإلداري لمن یقوم بتعبئة االستبیان
Manager. مدیر Vice Manager نائب مدیر Project Manager مدیر مشروع
Site Engineer مھندس موقع 5. Number of employees. بالشركةعدد الموظفین …………………………………………..
APPENDIX B THE QUESTIONNAIRE Factors affecting quality in construction projects Supervisor: Dr. Rifat Rustum
___________________________________________ _________________________________________ Student :Moh’d Issam Amer
١١١ S
6. Type of projects your company dealing with. نوع المشاریع التى تنفذھا الشركة
Infrastructure بنیة تحتیة Construction أنشاءات Others(Please specify) أخرى
……………………
7. Number of projects executed in the last five years. عدد المشاریع المنفذة خالل الخمس سنوات األخیرة
Less than 10 ١٠أقل من 11 to 20 ٢٠ الى ١١ 21 to 30 ٣٠الى٢١
More than 30 ٣٠أكثر من 8. What is the dollar value of construction work done in the last five years? ما قیمة ا ألعمال المنفذة خالل الخمس سنوات األخیرة
Less than 2 million dollars ملیون دوالر ٢أقل من 2 to 5 million dollars ملیون دوالر ٥ الى ٢ 5 to 8 million dollars ملیون دوالر ٨ الى ٥
More than 8 million dollars ملیون دوالر٨أكثر من
APPENDIX B THE QUESTIONNAIRE Factors affecting quality in construction projects Supervisor: Dr. Rifat Rustum
___________________________________________ _________________________________________ Student :Moh’d Issam Amer
١١٢ S
Section II : Quality in your Organization. مدى تناول الجودة فى الشركة
9. Has your organization developed a clear definition of quality? اضح للجودة داخل الشركة؟ ھل تم تحدید تعریف و
Yes نعم No ال Can’t say ال یوجد إجابة
10. Percentage of employees who are aware of the importance of quality………………….
نسبة الموظفین المعنیین بأھمیة الجودة
11. Does your organization have a quality improvement plan? ھل تطبق الشركة نظام تحسین الجودة؟
No أال Such a plan is under consideration. ھذا النظام تحت الفحص It has been implemented recently. لقد تم تطبیق نظام تحسین الجودة حدیثا
It has been implemented for some time now. لقد تم تطبیق نظام تحسین الجودة منذ بعض الوقت
12. Does your quality improvement plan have the full support of top management? ھل یتم دعم برنامج تحسین الجودة من المستوى األعلى فى الشركة؟
Yes نعم No. ال Can’t say. ال توجد إجابة
13. Has your company got the ISO certificate ? Yes No
14. If the answer is Yes, mention the year of having ISO certificate ………………………………………………
APPENDIX B THE QUESTIONNAIRE Factors affecting quality in construction projects Supervisor: Dr. Rifat Rustum
___________________________________________ _________________________________________ Student :Moh’d Issam Amer
١١٣ S
Section III: Main Factors affecting Quality in construction projects during construction phase.
العناصر الرئیسیة المؤثرة فى الجودة في مشاریع اإلنشاءات خالل مرحلة التشیید13. Please identify (carefully) the degree of importance of elements effected quality in your construction project:
. حدد درجة األھمیة للعوامل المؤثرة فى الجودة فى مشاریع اإلنشاءات
Very important = 5 Important = 4 Medium important=3 Low important =2 ) مھم جدا( )مھم) (مھم بدرجة متوسطة) (مھم بدرجة قلیلة (
Very low important = 1
)مھم بدرجة قلیلة جدا(
Degree of Importance No.
Main Quality Elements 5 4 3 2 1
1 Project (type and complexity) ) المشروع ودرجة التعقیدنوع( المشروع
2 Design التصمیم
3 Contract العقد
4 Material المواد الخام
5 Labor العمالة
6 Equipment المعدات
7 Subcontractors لباطن مقاولي ا
8 Site layout الموقع العام
9 Systems (quality control, cost control, safety program ) ) التحكم بالجودة ، ضبط التكلفة ، نظام السالمة(األنظمة المستخدمة
10 Site staff طاقم الموقع
11 Execution ( continuous supervision, using shopdrawing) ) األشراف المستمر ، استخدام خرائط تنفیذیة(طریقة التنفیذ
12 Financial issues الوضع المالى
13 Owner (public, private) ) عام ، خاص(طبیعة المالك
14 Environment (political , economical) ) الوضع السیاسى ،الوضع األقتصادى( البیئة المحیطة
APPENDIX B THE QUESTIONNAIRE Factors affecting quality in construction projects Supervisor: Dr. Rifat Rustum
___________________________________________ _________________________________________ Student :Moh’d Issam Amer
١١٤ S
Section IV : Sub-factors affecting quality 14. Please cross what you think is most relative to the degree of importance of each factor affecting quality in construction projects.
.حدد درجة األھمیة لكل من العوامل التى تؤثر فى الجودة فى مشاریع اإلنشاءات 5=Very important
) مھم جدا ) 4=Important
) مھم( 3=Medium important
) مھم بدرجة متوسطة( 2=Low important
) مھم بدرجة قلیلة( 1=Very low important
) مھم بدرجة قلیلة جدا(
Degree of Importance NO. Group Factor 5 4 3 2 1
Scope of the project ( type and nature of the project)
نوع وطبیعة المشروع
Location of the project مكان المشروع
Site access سھولة الوصول الیھ
1. Factors related to project عوامل تتعلق بالمشروع
Period of the project مدة المشروع
Completeness and consistency of design documents.
شمولیة وترابط وثائق التصمیم
Drawings are prepared in full details استخدام رسومات تحتوى على جمیع التفاصیل
Conformance to codes and standards التوافق مع القواعد واألكواد الھندسیة
Adherence to specifications االلتزام بالمواصفات
2. Factors related to design عوامل تتعلق بالتصمیم
Bill of quantity is very detailed and accurate. جدول الكمیات دقیق ویحتوى على جمیع التفاصیل
APPENDIX B THE QUESTIONNAIRE Factors affecting quality in construction projects Supervisor: Dr. Rifat Rustum
___________________________________________ _________________________________________ Student :Moh’d Issam Amer
١١٥ S
Degree of Importance No. Group Factor 5 4 3 2 1
Cooperation between parties involved in contract التعاون بین األطراف المشاركة فى العقد
Previous successful relations between parties یوجد عالقة سابقة ناجحة بین األطراف
A written contract with conditions clear and fair and responsibilities distribution is clear شروط العقد واضحة مع توزیع للمسؤولیات
Using a standard contract استخدام نظام العقد الموحد
3. Factors related to contract عوامل تتعلق بالعقد
Type of Awarding system نوع نظام ترسیة العطاءات
Using a complete applied material management system. استخدام نظام شامل الدارة المواد
Cooperation between contractor and material suppliers
التعاون بین المقاول وموردي المواد
Availability of good quality construction materials
توفر المواد ذات الجودة العالیة
Using storage and handling system استخدام نظام تخزین وشحن
4. Factors related to materials عوامل تتعلق بالمواد الخام
Construction material monopoly حتكار المواد الخام من قبل الموردینا
Labor management system نظام إدارى للعمال
Using labors with high experience رة استخدام عمال ذوى خب
Using Motivation System استخدام نظام الحوافز للعمال
Training courses for labors دورات تدریبیة للعمال
5. Factors related to labors عوامل تتعلق بالعمال
Income level and wages of labors مستوى دخل و أجور العمال
APPENDIX B THE QUESTIONNAIRE Factors affecting quality in construction projects Supervisor: Dr. Rifat Rustum
___________________________________________ _________________________________________ Student :Moh’d Issam Amer
١١٦ S
Degree of Importance No. Group Factor 5 4 3 2 1
Availability of Equipment توفر المعدات
Equipment management system نظام إداري للمعدات
Measurement of equipment productivity
قیاس إنتاجیة المعدات
Good utilization of equipment االستخدام الجید للمعدات
6. Factors related to Equipment عوامل تتعلق بالمعدات
Equipment maintenance صیانة المعدات
Company’s methods and procedures of selecting subcontractors طرق وإجراءات الشركة فى اختیار مقاولي الباطن
High cooperation between subcontractors and general contractor التعاون الوثیق بین مقاولى الباطن والمقاول
الرئیسى
Using a system to evaluate subcontractors performance استخدام نظام لتقییم أداء مقاولى الباطن
7. Factors related to subcontractors عوامل تتعلق بمقاولي الباطن
Good and fair subcontract conditions عقد مقاولة الباطن یتمیز بشروط جیدة و عادلة
Site layout is large and suitable for movement of labors and equipment الموقع العام واسع ویتمیز بسھولة الحركة للعمال والمعدات
Site layout is organized well الموقع العام منظم بشكل جید
Site layout has storage areas for materials یتمیز الموقع العام بوجود أماكن لتشوین المواد
8. Factors related to site layout عوامل تتعلق بالموقع العام للمشروع
Site is clean نظافة الموقع العام
APPENDIX B THE QUESTIONNAIRE Factors affecting quality in construction projects Supervisor: Dr. Rifat Rustum
___________________________________________ _________________________________________ Student :Moh’d Issam Amer
١١٧ S
Degree of Importance No. Group Factor
5 4 3 2 1 Using computer software and applications
استخدام برامج و تطبیقات الكمبیوتر
Implement quality control and assurance system تطبیق أنظمة المراقبة والتحكم فى الجودة
Implement and using Time Schedule تطبیق واستخدام الجداول الزمنیة
Using cost control system استخدام نظام ضبط التكلفة
9. Factors related to systems عوامل تتعلق باألنظمة المستخدمة
Implement a safety program تطبیق برنامج الوقایة والسالمة
Cooperation between Supervision and Contractor’s staff التعاون بین طاقم األشراف والمقاول
Understanding of contract administration by Supervision الفھم الجید ألدارة العقود من قبل طاقم األشراف
Skill and experience Supervision staff مھارة وخبرة طاقم االشراف
10. Factors related to site staff عوامل تتعلق بطاقم الموقع
Skill and experience Contractor’s staff ارة وخبرة طاقم المقاولمھ
Using a complete execution system استخدام نظام إشراف شامل ومستمر
Testing for final products only فحص المراحل النھائیة للعمل فقط
Clear procedure for accepting performed activities خطوات واضحة الستالم األعمال
11. Factors related to execution عوامل تتعلق بطریقة التنفیذ
Preparing and using shopdrawings إعداد واستخدام رسومات تنفیذیة
The amount of contractor’s cash flow
كمیة التدفق المالى عند المقاول 12.
Factors related to Financial issues
The non delay of interim payments عوامل تتعلق باألمور المالیة عدم تأخر الدفعات المرحلیة
APPENDIX B THE QUESTIONNAIRE Factors affecting quality in construction projects Supervisor: Dr. Rifat Rustum
___________________________________________ _________________________________________ Student :Moh’d Issam Amer
١١٨ S
Degree of Importance No. Group Factor
5 4 3 2 1 Owner organization nature (Public or Private)
) مؤسسة عامة أو خاصة(طبیعة المالك
The Owner is not delaying to make decisions عدم تاخر المالك فى اتخاذ القرارات الالزمة
Owner’s contribution to design مدى مشاركة المالك فى مرحلة التصمیم
13. Factors related to Owner عوامل متعلقة بالمالك
Owner’s emphasis on quality مدى اھتمام المالك فى الجودة
The socio-economic environment البیئة االجتماعیة واالقتصادیة
Stability of Political environment ثبات الوضع السیاسى
Closure of Gaza Strip األغالق على قطاع غزة
14. Factors related to environment
ة عوامل تتعلق فى البیئ
The relations between construction industry and the other industries
العالقات بین صناعة اإلنشاءات والصناعات المختلفة األخرى
With best regards