modelling the factors affecting quality of …...construction project are: characteristics of site...

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


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


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


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


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.


Do Contracting Companies who have an ISO certificate differ in ranking the quality

factors from the other companies who do not have this certificate?


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.


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


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.


Do the position of the respondent affect the ranking of the quality factors?


There is a significant difference in perception between the manager, deputy

manager, project engineer and site engineer towards ranking quality factors.


There is no difference between the manager, deputy manager, project engineer and

site engineer towards ranking quality factors.


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


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.

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١٠٠

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١٠١

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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


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.)


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…………………………………………………………….


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………………………………………………………….


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



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 …………………………………………..



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



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 ………………………………………………



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



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



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


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



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



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



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

modelling the factors affecting quality of …...construction project are: characteristics of site...

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