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IDENTIFICATION OF THE FACTORS AFFECTING QUALITY IN BUILDING
CONSTRUCTION PROJECTS IN GAZA STRIP
Rifat N. Rustom1 and Mohammad I. Amer 2
ABSTRACT
This research is intended to provide clients, project managers, designers, and contractors with the
necessary information needed to better manage the quality of building construction projects in Gaza Strip.
The paper reports the findings of a research study, which was undertaken to determine the underlying
factors affecting quality of building construction projects in Gaza Strip. Nominal Group Technique
(NGT) was used at the preliminary stage to identify these factors and to assist in developing a
questionnaire to identify and rank these factors and the associated sub-factors. The NGT yielded 8 main
factors and 16 sub-factors. Combining the results of previous research studies and NGT results yielded 14
main factors and 60 sub-factors. The perception of practitioners is obtained by means of this
questionnaire. 65 contracting companies and 24 consulting offices participated in responding to the
questionnaire. The sub-factors that influence the quality of building construction projects and their
relative importance were identified and used in identifying the main factors using the weighted average
sum method. Pareto analysis showed that 10 main factors contribute 74% of the weight of all factors.
Among the most significant factors identified are: experience of site staff, consistency of design
documents, the financial power of the contractor, availability of construction materials, subcontractors,
and the control systems used.
KEYWORDS: Quality, NGT, construction industry, quality factors, Gaza Strip.
1. INTRODUCTION
Quality has become a very popular subject in recent years due to conceptual changes in
the industry. Quality and quality systems are topics which have been receiving
increasing attention worldwide [1]. The finished product in any industry should be
manufactured to a required standard, one that provides customer satisfaction and value
for money. The need for achieving quality of the finished product in the building
construction industry is no less than in any other industry. The high cost of buildings
makes it necessary to ensure quality of the finished product [1]. 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 developing countries. Efforts to improve quality in
developing countries should be based on methods that stem from their economic and
technological backgrounds [2]. Therefore, determining the local construction industry’s
viewpoint on the factors which would improve the quality of building construction
projects in Gaza Strip, and the relative importance of each factor, is an essential first
step towards establishing methods for a real improvement of building construction
projects in Gaza Strip.
1
2
Islamic University-Gaza, Palestine, Associate Professor of Civil Engineering
UNRWA- Palestine, Area Construction Engineer
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Therefore, the main objective of this study is to obtain local consensus on the factors
affecting quality improvement that represent the views of the building construction
industry in Gaza Strip and to determine the relative importance of these factors.
2. BACKGROUND
Definitions of quality are abounding. For many years there have been attempts to define
the meaning of quality, often in general terms. Some definitions result from
authoritative documentation, while others express experiences, opinions, and conjecture.
Although considerable disparity prevails, there is also much common grounds 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” [3]. A second definition is “fitness for purpose/use”. This
definition is driven by customer satisfaction, and has become the principal definition of
quality in manufacturing and service industry [4]. A third definition of quality is
“uniformity of the product characteristics or delivery of a service around a nominal or
target value”. This definition of quality concerned about locating the product
characteristics and process parameters within the design specifications or tolerance
limits [4].
Quality policy is the overall intentions and directions of an organization as regards to
quality, as formally expressed by top management [3]. Quality management is all
activities of the 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
[3]. Project Management Body of Knowledge (PMBOK), a guide to the project
management, states that project quality management is a subset of project management
that includes the process required to insure that the project will satisfy the needs for
which it was undertaken. It consists of quality planning, quality assurance and quality
control [5]. Quality system is defined as “organizational structures, procedures,
processes and resources for implementing quality management [3]
Various attempts have been made by different resources to determine the critical quality
factors in building construction projects. The literature abounds with lists of variables
supposedly influencing quality. There are some variables common to more than one list,
but there is certainly no general agreement on the variables. Review of these previous
research variables reveals some common threads of variables affecting the quality of a
building construction project. Chan and Tam [1] 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
action. Abdel-Razeq [6] stated that the elements affecting building construction projects
are design, contract, material, labor, equipment, subcontractors, site layout, systems, site
staff, and execution. Tan and Lu [7] grouped the elements affecting quality of building
construction projects in Taiwan into eight criteria: manpower qualified to achieve
project mission, conformance to codes and standards, conformance to owner’s
requirements, conformance to design process and procedures, conformance to schedule
requirements, conformance to cost requirements, and constructability.
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3. RESEARCH METHODOLOGY
The methodology of the study is as presented in Figure 1.
Research Methodology
Identifying Local
Quality Factors
by NGT
Identifying Quality
Factors base on
Former Studies
Questionnaire Design
Ranking Sub-factors
Pareto Analysis
Weighted Average Method
Defining the Most Important
Factors and Their Relative
Importance
Figure 1: Research Methodology
A thorough literature review was conducted to identify the factors that affect quality as
recognized by researchers and practitioners in this field. The factors affecting quality in
Gaza Strip were identified using Nominal Group Technique [8]. 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 variables, rather than in
the usual interactive mode of conventional groups. It is a special purpose technique,
useful for situations where individual judgments must be tapped and combined to arrive
at decisions that cannot be reached by one person. In this study, the application of NGT
was carried out in the Islamic University of Gaza with the writers of this study acting as
the facilitators. Seven consultants, nine contractors, and six owner’s representatives
participated in the session.
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 building construction
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projects during construction phase”. For this portion of the session individual behavior
is sought.
The second phase is the round-robin phase. The facilitator called on participants to
engage in groups. Each group discussed the individual ideas, agreed on and recorded a
list of ideas. This phase goes until all the ideas generated by the group were listed and
displayed.
The third phase is called clarification. Once all the ideas have been recorded, one of the
participants from each group was called to offer clarification of ideas to produce a list of
the factors affecting quality.
The fourth phase, voting and ranking, the participants were called to make an open
discussion 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.
The session closed with a brief discussion of the results of the voting process in which
the facilitator emphasized those factors on which there is strong consensus. The NGT
session generated 8 main factors and 16 sub-factors affecting quality of building
construction projects in Gaza Strip.
4. OVERALL FACTORS AFFECTING BUILDING CONSTRUCTION PROJECTS
Combining the results of the literature review with the results of the Nominal Group
Technique session, the overall factors affecting quality were identified. These factors
were aggregated into fourteen groups (main factors). Each group is divided into subfactors as shown in Table 1.
Table 1: Factors Affecting Quality of Building Construction Projects in Gaza Strip
No
Main Factor
Sub-factors
1.
Project
2.
Design
3.
Contract
Scope of the project (type and nature)
Location of the project
Site access
Period of the project
Completeness and consistency of design documents
Drawings are prepared in full details
Conformance to codes and standards
Adherence to specifications
Bill of quantity is detailed and accurate
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
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4.
Material
5.
Labor
6.
Equipment
7.
Subcontractors
8.
Site layout
9.
Systems
10.
Site staff
11.
Execution
12.
Financial Issues
13.
Owner
14.
Environment
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
Labor management system
Using labor with high experience
Using motivation system
Training courses for labor
Income level and wages of labor
Availability of equipment
Equipment management system
Measurement of equipment productivity
Good utilization of equipment
Equipment maintenance
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
Site layout is large
Site layout is organized well
Site layout has storage areas for materials
Site layout is clean
Software and computer applications
Implement quality control and assurance system
Using time schedule
Using cost control system
Implementing a safety program
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
Using integrated project execution system
Testing for final products only
Clear procedure for accepting performed activities
Preparing and using shop drawings
Amount of contractor’s cash flow
Non-delay of interim payments
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
Socio-economic environment
Stability of Political environment
Closure of Gaza Strip
The relations between construction industry and other
industries
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5. QUESTIONNAIRE DEVELOPMENT
An eight-page questionnaire was developed as a research tool for this study. The
questionnaire consisted of four sections:
-Section One: respondent's 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 this section and scores resulted from
ranking the sub-factors presented in section four. This comparison
will check the priority order of main factors in both rankings.
-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 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 respondents were asked to assess the main factors and sub-factors
affecting quality in building 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 5 represents very important.
5.1 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 agreed that the questionnaire is suitable to achieve the studying goals with some
amendments.
5.2 Research Sample
Two types of population were considered in this study. The first population is
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. 65 out
of 92 Contracting Companies are used in the survey. The second population is the
Engineering Consulting Offices, who were registered by the Engineering Association in
Gaza Strip at year 2002. 24 out of the twenty seven Consulting Offices also participated
in the survey.
5.3 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
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package [9], which reflected Alfa coefficient to be 0.83. It is considered to be highly
significant at 0.05 level and this ensured the reliability of the scale.
6. THE WEIGHTED AVERAGE METHOD
To define the relative importance of each main factor, the weight of the sub-factors of
section 4 in the questionnaire (see Table 1) was calculated using the following formula.
Factor Average Weight =
Summation of scores of sub-factor in each group
Total No. of factors in each group* Total No. of respondents
Comparing the results of ranking the main factors and the sub-factors and by using the
Weighted Average Method, the results lead to almost the same order of priority as
explained in Table 2.
Table 2: 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
7. PARETO ANALYSIS
In order to classify the distribution pattern of the quality factors obtained, Preto analysis
[8] was carried out. The data collected from ranking the sub-factors at Section 4 in the
questionnaire are analyzed, concluding the score and relative percent of each factor. The
results of Pareto Analysis are shown in Table 3 and illustrated in Figure 2. They show
the 14 main factors affecting quality together with the contribution of each factor as
average score and a percentage respectively. The results of Pareto Analysis show that
the first 10 factors contribute to about 74% of the weight of all the factors. These 10
factors can be considered as the most important factors affecting quality.
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Table 3: Pareto Analysis of the Quality Factors
No.
Main
Quality Sub-factor
Score
Factor
1.
2.
Site Staff
Design
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
Completeness and consistency of
design documents
Drawings are prepared in full details
Conformance
to
codes
standards
Adherence to specifications
3.
4.
6.
7.
400
403
386
390
Subcontrac
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
Using a comprehensive material
management system
Cooperation between contractor and
material suppliers
Availability of good quality
construction materials
Using storage and handling system
393
410
383
%
%
411.5
8.18
8.18
401.2
7.97
16.15
400
7.96
24.11
374
7.44
31.55
366.2
7.28
38.83
363.4
7.23
46.06
359
7.13
53.19
357
363
367
359
397
356
Construction materials monopoly
352
Labor management system
406
Using labor with high experience
413
Using motivation system
338
Training courses for labor
320
Income level and wages of labor
340
Software and computer applications
343
Implement quality
assurance system
using time schedule
375
and
385
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Weight
413
Non delay of interim payments
control
Weight
407
issues
Systems
Score
422
Financial
Labor
Cumulative
409
397
Material
Average
415
Bill of quantity is detailed and
accurate
Amount of contractor’s cash flow
tors
5.
and
Average
8.
9.
10.
11.
12.
13.
14.
Using cost control system
350
Implement a safety program
342
Environme
Socio-economic environment
327
nt
Stability of political environment
381
Closure of Gaza Strip
401
The relations between construction
industry and the other industries
Cooperation
between
parties
involved in contract
Previous
successful
relations
between parties
A written contract with clear
conditions
Using a standard contract
313
Type of awarding system
354
Using
Integrated
project
management execution system
Testing for final products only
407
Clear procedure for accepting
performed activities
Preparing and using shop drawings
360
Availability of equipment
375
Equipment management system
319
Measurement
of
equipment
productivity
Good utilization of equipment
303
Equipment maintenance
333
Site layout is large
340
Site layout is organized well
343
Site layout has storage areas for
materials
Site layout is clean
333
Owner organization’s nature (public
or private)
Owner’s quick response (no delays
in making decisions)
Owner’s contribution to design
309
Owner’s emphasis on quality
340
Scope of the project
335
Location of the project
302
Site access
307
Period of the project
321
Contract
Execution
Equipment
Site Layout
Owner
Project
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355.5
7.07
60.26
348.6
6.93
67.19
336.75
6.69
73.88
336
6.68
80.56
332.25
6.61
87.17
329.25
6.55
93.72
316.25
6.28
100
370
315
371
333
199
381
350
313
351
317
120
9
8
% Factor weight
80
6
5
60
4
3
F a c to r's W e ig h t (% )
2
C u m u la tiv e W e ig h t (% )
1
0
40
% Cumulative weight
100
7
20
0
f1
f2
f3
f4
f5
f6
f7
f8
f9
f1 0 f1 1 f1 2 f1 3 f1 4
F a cto r n u m b er
Figure 2: Pareto Analysis of Quality Factors
8. DISCUSSION
The goal of high quality is common to all countries. This common goal must compete
with other national goals amid the massive national forces (e.g. political, economic, and
social) which determine national priorities. The current study outlines the major factors
influencing the construction industry in Gaza Strip under the prevailing hardships
(current Palestinian Intifada).
The study shows that Site Staff (both contractor and consultant staff) is found to be very
important and is ranked first. The skills and experience of the contractor and
supervision staff showed the highest score among the sub-factors influencing quality as
shown in Table 3.
The contractor’s involvement in supervision is important especially if work is
subcontracted. As shown in Table 3, the contractor's procedure of selecting
subcontractors and the cooperation between the subcontractors and the contractor are
among the major factors influencing quality. Lack of information and overlapping
activities, which are common on construction sites, may result in rework, high costs,
and low quality performance. Effective coordination by the different teams of Site Staff
may increase the effectiveness of the work and project completion.
Design documents are shown to have the second priority in importance. Drawings and
specifications are the two sets of documents given to the contractor that provide
technical information on materials, performance of the construction facility, and quality
requirements. Drawings are the only documents given to the contractor that show the
design concept, size and scope of the job, number and size of materials or items, and
how they are assembled into a final project. All these sub-factors are summarized in
terms of importance in Table 3.
The financial power of the contractor has a pivot role in completing the project on time
and with the stated performance requirements. Financial problems and lack of cash flow
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will adversely affect the progress of construction. Most ongoing projects in Gaza Strip
are donor funded projects. In most cases, the donors stipulate their own payment
conditions. The prolonged procedure and payments duration as well as the different
systems followed by these donors confuse the contractors and result in financial
problems. Although there is no local published work to show the impact and magnitude
of this issue, however, most contractors interviewed pointed out this problem.
The adaptation of a good material management system helps in improving quality of the
project. Controlling the delivery time of construction material to the site leads to
easement of implementation of different construction activities and decreases
interruptions. One of the major sub-factors highlighted by the respondents that affect
quality is the availability of good quality construction materials. During the current
political turmoil in Gaza Strip, the resources of the construction materials have been
monopolized. Therefore, the availability of good material with reasonable market prices
is not guaranteed at most times.
Labors have an important role toward improving quality of the project. Highly
experienced labor is among the main sub-factors influencing quality. Low wages and
very few job opportunities in Gaza Strip adversely impacted the labor force where
highly qualified labors are avoided to minimize the contract prices.
The different systems used in the construction project are found to be important factors
affecting quality. Quality assurance and quality control are among these systems. Tools
and techniques like time scheduling is ranked among the major sub-factors that help in
improving the overall quality of the project.
As Gaza Strip is considered a devastated area by many international agencies, the
political environment and the frequent closure and siege of Gaza Strip affect directly the
quality of projects. The closure of Gaza Strip negatively impacted the construction
industry in terms of material availability, construction materials conformance to
standards, prices fluctuation, and cash flow interruption. These factors caused the delay
of most projects in addition to many disputes with the supervision staff due to the low
quality material.
As indicated in Table 3, many sub-factors contribute to quality in varying degrees. The
interrelationships among these sub-factors and quantification of these relationships are
currently under investigation.
The findings of this study generally conform to many other research studies. However,
the relative weights of the main factors and sub-factors differ among these studies, thus
reflecting the particularity of each country's conditions. Abdel-Razeq [6] showed that
Site Staff, Contract, Material, Subcontractors, Labors, Systems and Execution Methods
are main factors influencing quality performance in Egypt. In this research study, the
Environment factor was added to these most important factors affecting quality as Gaza
Strip suffers extremely from the instability of the political situation and Israeli
Occupation problems. This fact was supported by Chan and Tam [1] who pointed out
that Environment is one of the factors affecting quality.
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9. CONCLUSION
This study shows that among the 14 main factors and 60 sub-factors, Site Staff, Design,
Financial Issues, Subcontractors, Material, Labors, Systems, Environment, Contract,
and Execution are the main factors influencing quality. The analysis of results showed
that these 10 main factors contribute 74% of the total weight of all factors.
The political environment and closure of Gaza Strip has adversely affected the quality
of building construction projects. The interrelationship of environment factor with many
other factors influenced the ranking of these factors.
Improvements in the aspect of work related to these factors should make it possible
progressively to improve quality in Gaza Strip. The results showed that there is an
obvious need for extensive studies on how to improve quality on both national and a
company level. The present study is an essential first step towards highlighting the
major issues that need attention to improve the quality of building construction projects
in Gaza Strip. More efforts is still needed to investigate ways to formulate management
systems (policies and procedures) to handle each factor individually.
10. REFERENCES
[1] Chan, A.P and Tam, C.M., “Factors affecting quality of building projects in Hong
Kong”, International Journal of Quality and Reliability Management, Vol.17 Nos. 4/5,
PP.423-441, 2000.
[2] Abdel-Razeq, R.H., ”Factors Affecting Construction Quality in Egypt: identification
and relative importance”, Journal of construction and Architectural Management. Vol.3,
PP. 220-227, 1998.
[3] McCabe, S., “Quality Improvement Techniques in Construction”, Addison Wesley
Longman Limited, 1998.
[4] El-Sawah, H., ”Quality Management Practices in the Egyptian Construction
Industry”, International Exhibition Conference for Building & Construction, Egypt,
1998.
[5] Project Management Institute, ”A Guide to the Project Management Body of
Knowledge”, 2000. http://www.pmi.org/info/pp-standardsexcerpts.asp
[6] Abdel-Razeq, R.H., El-Dosouky, A.I. and Solaiman, A.M., ”A Proposed Method to
Measure Quality of the Construction Project”. International Exhibition Conference for
Building & Construction, Egypt, 2001.
[7] Tan, R.R and Lu, Y.G., ”On the Quality of Construction Engineering Design
Project: Criteria and Impacting Factors”, International Journal of Quality &Reliability
Management. Vol.12, No.5, PP. 18-37, 1995.
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[8] Abdel-Razeq, R.H., ”Quality Improvement in Egypt: Methodology and
Implementation”. Journal of Construction Engineering and Management. Vol.124,
No.5, 1998.
[9] Safi, S.K., ”Statistical Package for the Social Sciences”, Afak Publishing Co., Gaza,
2001.
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