contributors to construction delays
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Contributors to construction delays.
Kumaraswamy, Mohan M.
Chan, Daniel W. M.
Construction Management & Economics; Jan1998, Vol. 16 Issue 1, p17-29, 13p, 1
Diagram, 14 Charts, 1 Graph
Article
*CONSTRUCTION industry
*PROJECT management
*INDUSTRIAL engineering
*INDUSTRIAL productivity
*QUESTIONNAIRES
HONG Kong (China)
CHINA
delay
Hong Kong
Hong Kong.
PRODUCTIVITY
project management
time
Projects can be delayed for a large number of reasons. The third phase of an
investigation into such factors focused on the causes of construction delays in
Hong Kong. A questionnaire was based on 83 factors identified in previous phases
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of the investigation. Analysis of the responses reveals differences in perceptions
of the relative significance of factors between clients, consultants and contractors.
There was general agreement about the relative importance of delay factors such
as unforeseen ground conditions. Improving productivity is a useful approach to
controlling delays. Important factors affecting productivity itself are thus examined
in more depth, with a view to enhancing productivity and reducing delays. The
conclusions of this phase of the investigation include a ranking of factors and
factor categories that are perceived by different groups of project participants to
contribute to delays. For example, higher-ranking factors, such as unforeseen
ground conditions, and factor categories such as project-related factors, are found
to merit special management attention in countering construction delays. The high
degree of disagreement as discerned between the groups of clients, consultants
and contractors is indicative of their experiences, possible prejudices and lack of
effective communication. It is also confirmed that productivity and other non-scope
factors such as effective communications should supplement the project scope
factors incorporated into the construction time prediction models that were
proposed in the previous phases of this investigation. [ABSTRACT FROM
AUTHOR]
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Department of Civil and Structural Engineering, The University of Hong Kong,
Pokfulam Road, Hong Kong.
6285
0144-6193
10.1080/014461998372556
253021
Business Source Premier
1
CONTRIBUTORS TO CONSTRUCTION DELAYS
Received 26 October 1995; accepted 8 July 1996
Projects can be delayed for a large number of reasons. The third phase of an investigation into such
factors focused on the causes of construction delays in Hong Kong. A questionnaire was based on 83
factors identified in previous phases of the investigation. Analysis of the responses reveals differences
in perceptions of the relative significance of factors between clients, consultants and contractors.
There was general agreement about the relative importance of delay factors such as unforeseen
ground conditions. Improving productivity is a useful approach to controlling delays. Important factors
affecting productivity itself are thus examined in more depth, with a view to enhancing productivity and
reducing delays. The conclusions of this phase of the investigation include a ranking of factors and
factor categories that are perceived by different groups of project participants to contribute to delays.
For example, higher-ranking factors, such as unforeseen ground conditions, and factor categories
such as project-related factors, are found to merit special management attention in countering
construction delays. The high degree of disagreement as discerned between the groups of clients,
consultants and contractors is indicative of their experiences, possible prejudices and lack of effective
communication. It is also confirmed that productivity and other non-scope factors such as effective
communications should supplement the project scope factors incorporated into the construction time
prediction models that were proposed in the previous phases of this investigation.
Keywords: productivity, project management, delay, time, Hong Kong
Background and introduction
The first two phases of an ongoing investigation into factors affecting construction durations in Hong
Kong (Chan and Kumaraswamy, 1995) focused on project scope variables such as project cost, floor
area and number of floors in buildings. The results were similar to those previously derived by
Bromilow et al. (1988) in Australia and Kaka and Price (1991) in the UK, in respect of the types of
relationship and the correlation between project time and cost. The previous investigation also
indicated the probable impact on construction durations of non-scope factors such as external and
management variables, in line with the conclusions from a recent study in Australia (Walker, 1995a).
Previous reports on the ongoing study into construction time performance in Hong Kong noted that: (a)
productivity was a key factor needing further study (Kumaraswamy and Chan, 1995); and (b) site
organization variables also merited further investigation, in relation to project durations (Chan and
Kumaraswamy, 1995). Furthermore, the second phase of the Hong Kong investigation also
incorporated a case study on construction plant and labour productivity. This indicated the contribution
of productivity levels to activity times, overall construction project durations and construction delays,
for example through different utilization/idling patterns.
This paper highlights the principal findings of the third phase of the Hong Kong investigation, in respect
of the main factors causing delays, as perceived by different industry subsectors: clients, consultants
and contractors. The degree of agreement/disagreement between the subsectors as to the
importance of these factors is also indicated, to illustrate differences in collective perspectives and
any possible popular misconceptions or prejudices. The resulting sectoral and combined rankings of
the main causes of construction delays suggest suitable priorities in devising and focusing strategies
to counteract such critical contributors to delays in future projects.
In developing such counter-delay strategies, a focus on productivity is justified by the main findings of
the questionnaire and literature surveys, both of which indicate a general perception of the significance
of 'non-scope' factors that either directly or indirectly affect productivity levels and project durations.
Lower productivity than planned is thus identified as a key contributor to (or a root cause of) delays,
which therefore merits special attention.
The findings of this phase of the investigation are framed within the context of relevant results of
recent research into construction productivity and other factors affecting construction durations and
construction delays in other countries, in order to consider the general applicability of the conclusions.
Productivity, project durations and delays
Because productivity levels were found to be a principal determinant of project durations (Chan and
Kumaraswamy, 1995), lowered productivity could feasibly contribute significantly to project delays.
The potential for improvement is reflected in the finding that 'productivity rates in the United Kingdom
varied between one site and another by as much as three to one' (NEDO, 1989). Enhanced
productivity is evidently a necessary but not sufficient condition for reducing project durations. While
the productivity of each type of resource (factor), such as labour, may be increased, by motivation for
example, the overall (total factor) productivity will not be correspondingly enhanced unless a proper
balance and appropriate synergy is achieved. This requires effective management of the resources
and their interactions within the project, as well as their interactions with the external environment.
Conversely, project durations have been reduced in practice, despite lower productivity levels, for
example by mobilizing more resources. Seemingly impossible target dates have been achieved by
such deployment of additional resources and/or a sudden surge of synergistic 'partnering' type
teamwork by all project participants who needed to meet a critical deadline. Similarly, project delays
have also been caused by factors other than lowered productivity levels.
For the purposes of the third phase of this investigation, potential delay factors were identified from a
literature review and the observations from the first two phases of the investigation. These were
classified into eight factor categories as follows:
project-related;
client-related;
design team-related;
contractor-related;
materials-related;
labour-related;
plant/equipment-related;
external factors.
Although a certain degree of overlap may be anticipated between these categories, this was
minimized during the specific allocations of the 83 factors. It was noted that: (a) there may be
interactions between the factor categories, for example in one affecting the other either positively or
negatively; and (b) achieved (vs planned) productivity levels can affect many of the categories (as a
common root cause), for example in design team productivity, contractors' organizational productivity,
labour productivity and plant productivity.
Projects can be delayed by the impact of such factor categories; it was also noted that these may
interact to produce 'multiplier' effects, where problems in one category may trigger further problems in
another. For example, weak contractor management may lower labour morale, and decrease plant
productivity as well.
Survey methodology
The survey questionnaire was designed on the basis of 83 previously identified delay-causing factors
divided into the foregoing eight factor categories. Respondents were requested to rate the significance
of each factor as either extremely significant, very significant, moderately significant, slightly significant
or not significant. The first page of the five-page questionnaire is reproduced in Appendix 1.
This questionnaire was sent to 400 clients, consultants and contractors in Hong Kong in December
1994, requesting responses based on projects completed between 1990 and 1994. Follow-up
communications led to the return of 147 completed questionnaires. The distribution of the
respondents, as classified according to their industry grouping (clients, consultants or contractors)
and their main works type (buildings or civil engineering) is indicated in Appendix 2.
The profile of the respondents in terms of their average work experience in each such group, as
indicated in Appendix 3, confirms the considerable experience on which the responses are based. It is
noted that the subjective and general nature of the responses required would be less reliable than
more quantifiable information, or that obtained from specific projects. However, it must be also noted
that this survey supplements (and is supplemented by) a previous survey, which derived such
quantifiable data from specific projects (Chan and Kumaraswamy, 1995), but which also indicated the
need for wider experience-based assessments of factors causing delays. The questionnaire survey
was supplemented by follow-up interviews to clarify some of the responses.
Survey findings Observations and analysis
Table 1 presents a profile of the magnitudes of time overruns, as observed on different types of
projects during the first survey in 1993/94. This profile indicates that project delays are fairly common
in Hong Kong.
Tables 2 and 3 summarize the responses in respect of the 20 most important factors causing delays
as perceived by two of the six groups surveyed: contractors on building projects and consultants on
civil engineering projects, respectively. Four more of such summarized response sheets were
obtained for the other groups surveyed, but are not reproduced here, to save space. However, the
consolidated summaries that are presented later (in Tables 4, 5 and 8) reflect the comparative results
from the other groups as well.
The relative importance index (RII) derived to summarize the importance of each 'factor' was
computed as
Multiple line equation(s) cannot be converted to ASCII text
where: w = weighting as assigned by each respondent in a range from 1 to 5, where 1 implies 'not
significant' and 5 implies 'extremely significant'; A = the highest weight (5); N = the total number in the
sample.
The relative rankings of the factors within each group from 1 to 20 are also indicated in Tables 2 and 3.
These were assigned on the basis of the factor RIIs. Where the RIIs were the same for two or more
factors, rank differentiation was achieved by examining the distribution of the ratings against such
factors. For example, if more respondents had ranked one of the factors as either 'extremely
significant' or 'very significant' (i.e. more ranks of 4 or 5, than assigned to another factor), then the
former was assigned the higher rank.
The next step distinguished between building works and civil engineering works, thereby dividing each
of the three participant groups into two such work types, with each work type containing the three
groups of clients, consultants and contractors. The weighted average of the RIIs for each of the
previously selected 20 factors from each group was next computed within each work type, by
combining it with the RIIs from the other two groups. This combination of three RIIs to find the
weighted average for each factor within each work type was achieved by adding the products of (a)
the RII for each group and (b) the proportion of respondents from the corresponding group (as a
proportion of the total respondents, as can be derived from Appendix 2). For example, the weighted
average of the factor 'poor site management and supervision' in the 'building works' type, as in Table
4, was computed as 0.800 x (27/78) + 0.858 x (24/78) + 0.822 x (27/78) = 0.825, as appears in Table
4.
The ten factors with the highest weighted averages in the 'buildings works' and 'civil engineering
works' types are shown in Tables 4 and 5 respectively. Figures 1 and 2 facilitate a visual comparison
of the RIIs, (as derived from the perceptions of the different groups) of the ten most significant factors
in respect of the 'building works' and 'civil engineering works' types respectively.
The overall RIIs for each of the eight factor categories were next determined for each group in turn, by
taking the mean of all factor RIIs in that category. The weighted averages of these overall RIIs from the
factor categories were obtained for three building works groups as in Table 6; and for the three civil
engineering works groups as in Table 7.
The rank agreement factors (RAFs) were next computed using the formula and methodology
described by Okpala and Aniekwu (1988) to measure the agreement in ranking between groups of
project participants. The RAF can range from 0, indicating perfect agreement, to higher values
indicating increasing disagreement. The percentage disagreement and the percentage agreement
(PA) were computed from the RAF, also using the prescribed formulae.
Table 8 records the RAFs and PAs as computed for the ten most significant factors causing delays,
as perceived by the different groups. Table 9 records the RAFs and PAs in respect of the relative
importance of the eight factor categories themselves, as perceived by the different groups. A further
overall comparison between the building works and civil engineering works as a whole yields a RAF of
0.50 and a PA of 87.5%, indicating a high overall correlation. Figure 3 illustrates the proportions of
agreement between the different groups based on the PAs in Tables 8 and 9.
Specific conclusions from the survey
While the detailed results as indicated in Tables 2-9 and Figures 1-3 contain a wealth of information,
the following specific conclusions are relevant to the focus of this paper.
There is a fair degree of agreement between the groups in their ranking of the factor categories,
particularly between clients and consultants. However, there is an apparent divergence in perceptions
between clients and contractors, or even between consultants and contractors, on many specific
factors themselves: this is reflected in the percentage agreements (PAs) in Tables 8 and 9 and Figure
3.
For example, the clients and consultants appear to agree on the significance of the contractor-related
factor category in contributing to delays in both building works and civil engineering works, as per
Tables 6 and 7. However, an examination of the significant 'factors' so identified does not appear to
reflect this general perception to a corresponding extent in the case of the specific factors in Tables 4
and 5. This apparent anomaly could perhaps be explained, for example, as a general 'conditioning' of
one group (such as consultants) vis-a-vis another (such as contractors), which may manifest itself in
a random distribution of adverse responses relating to the latter group in general, i.e. within the
relevant factor category, despite a lack of agreement on specific factors.
The top ten significant factors as isolated separately for building works and civil engineering works, as
identified in Tables 4 and 5 respectively, yield six common factors, as listed in Table 10.
Of the remaining four significant factors from building works, two are contractor related, one is project
related, and the other is design-team related. On the other hand, three of the four remaining factors
from civil engineering works are contractor related, with the other -classified as labour related - also
usually being within the purview of the contractor.
It is evident that there are differences in the perceptions of different groups as to the causes of
construction delays. Such perceptions may be attributed to a certain degree of group bias, arising
either from some specific experiences, from limited exposure, and/or from conditioning by colleagues.
Even though the recorded experience levels of the survey respondents seem sufficiently high, and not
dissimilar between groups as in Appendix 3, some bias is evident in the group perceptions. Perhaps
the wording of the factors and the classification of the factor categories in the questionnaire itself may
also be re-examined to minimize any defensive posturing or 'buck passing' by different groups; but a
residual bias is apparent even if allowances are made for this possible distortion.
Unfortunately, such biases may be counterproductive: for example, when blaming other groups, rather
than examining the real causes of delays. Such differences of perception and their consequences can
also lead to claims for extension of time that generate further pressures to direct or deflect blame,
rather than seek root causes and solutions.
A re-examination of Tables 6 and 7 relating to significant factor categories indicates that project-
related factor categories rank only fifth in significance, whereas contractor-related, design-team-
related and labour-related factor categories rank first, second and third respectively. This suggests
that project- (or scope-) related factors are not that significant in the context of delays (although they
are important in establishing the project durations at the outset), in comparison with the
aforementioned first three factor categories, and even the fourth (external conditions). Furthermore,
case studies and interviews during this investigation indicated the importance of productivity levels of
the contractor, of the design team, and of the labour itself, in contributing to the significance of the first
three (as ranked) aforementioned factor categories. It was also noted that the wide variations possible
in such productivity levels could well contribute to project delays (Chan and Kumaraswamy, 1995).
The foregoing conclusion re-confirms previous findings, from this investigation and from the literature,
as to the significance of productivity in determining project durations and in contributing to delays. This
also suggests a re-examination of methods of measuring and improving productivity levels in
construction projects, as one important approach to avoiding or minimizing delays.
A re-examination of aspects of construction productivity that contribute to project delays
Concept and classifications
Commencing with the basic conceptualization of productivity as output/input, Prokopenko (1987)
identified three main productivity factor groups as:
job related;
resource related;
environment related.
He also distinguished between (a) external (non-controllable) and (b) internal (controllable) factors,
further subdividing the latter into hard factors (those related to product, plant and equipment,
technology, materials and energy) and soft factors (people, organization and systems, work methods
and management styles).
The importance of total factor productivity as against single factor productivity -- to construction
organizations and to the industry itself -- has been reported previously (Ganesan, 1984). The former
takes into account all input resources (factors), whereas the latter is usually useful only in the case of
a critical or scarce resource, such as skilled labour.
Improving productivity levels
The observations from the Hong Kong survey in the current investigation indicated the perceived
importance of contractor-related, design-team-related and labour-related factor categories. This
appears to: (a) align with the concept of increasing total factor productivity and of synergizing the
inputs to optimize the outputs; and (b) provide a reminder of the importance of organizational variables
in both contractors and design organizations. For example, the rapid response and constructive inputs
of design teams to site problems enhance productivity and reduce delays.
Special work study techniques such as multiple-activity charts and activity sampling have been
adapted and developed for measuring and improving construction productivity (Heap, 1987; McCaffer
and Harris, 1995), but there is little evidence as yet of their popular usage in the industry, for example
in structured and scientific approaches to developing improved work methods and in establishing and
improving work norms. Such techniques and tools can be useful to organizations with a longer-term
perspective: i.e. those prepared to invest in improved productivity despite short-term pressures or
priorities. Their usefulness is underlined by the significantly variable construction productivity levels
indicated by the literature (NEDO, 1989); and by the previous (second) phase of this investigation
(Chan and Kumaraswamy, 1995), which indicated potential improvements through better plant and
labour utilization and appropriate methodologies, for example in concreting.
Factors affecting productivity and project durations
Lim and Price (1995) cited (a) the following seven factors identified as affecting overall construction
productivity in Singapore:
buildability;
structure of the industry;
training;
mechanization and automation;
foreign labour;
standardization;
building controls.
and (b) the following ten factors identified as affecting labour productivity:
quality, number and balance of labour force;
motivation of labour force;
degree of mechanization;
continuity of work as affected by supply of materials, performance of other contractors or
subcontractors, availability and adequacy of technical information, and variations;
complexity of project;
required quality of finished work;
method of construction;
type of contract;
quality and number of managers;
weather.
The apparent complexity is magnified when considering: (a) the possibilities of interactions between
such factors affecting labour productivity, and (b) the fact that similarly complex networks of factors
may simultaneously affect other factor productivities, such as that of equipment. The consequential
impacts on project activities could well lead to project delays.
It is thus necessary to focus on critical factors affecting overall (or total factor) productivity. Maloney
(1983) confirmed that labour has a significant influence on construction productivity, and that
management in turn has a major impact on labour productivity. He identified sets of specific driving,
induced and restraining forces acting positively and negatively on productivity levels, and formulated
approaches based on such forces to facilitate productivity improvements.
Motivation of both management and labour can be hypothesized as a key contributor to productivity.
Methods of motivating personnel to increase productivity have been demonstrated by Khan (1993),
through applications of different human relations theories of motivation. Such enhancement of
productivity could help to counteract delays induced by other causes. Conversely, a lack of proper
management can, even 'by default', mobilize factors that adversely affect productivity and lead to
project delays.
Other factors affecting construction time performance
The literature review of recent research also revealed many factors that were found to affect
construction time performance, apart from those factors that achieved such effects through their initial
impact on productivity levels.
For example, Nkado (1995) demonstrated the prioritization of construction-time-influencing factors that
can be incorporated in an information system, which could then help in planning project durations. He
used 12 scope-related variables, such as gross floor area, to develop this particular model, but had
also previously examined a total of 33 time-influencing factors that had been identified from the
literature. From the latter, he identified the ten most important factors, including for example client and
designer's priority on construction time. He also identified the ten least important factors from this set
of 33, including for example the form of contract and its suitability for the project.
In a similar context, an investigation of the relationship between the building team, procurement
method and project performance by Naoum and Mustapha (1995) did not yield enough evidence to
confirm the claim that alternative procurement methods shorten construction times. Parallels can thus
be drawn with the work of Walker (1995b) in Australia, which 'revealed that contract type does not
affect the speed of construction', and that several client-related factors proved more significant,
particularly as to 'how well the clients or their representatives relate to the project team'. Walker
(1995a) also found that the 'four factors affect(ing) construction time performances and best practice
worldwide were:
construction management effectiveness;
the sophistication of the client and the client's representative in terms of creating and maintaining
positive project team relationships with the construction management and design team;
design team effectiveness in communicating with construction management and client's
representative teams;
a small number of factors describing project scope and complexity.
Such findings collaborate the results of the questionnaire survey in Hong Kong, as to the relative
significance of non-scope factor categories, such as 'contractor related', 'design team related' and
'labour related' in contributing the construction delays. Specific factors also highlighted as significant in
this study included poor site management and supervision, low speed of decision making involving all
project teams, delays in design information, and lack of communication between consultant and
contractor.
Concluding observations
The third phase of this investigation into factors affecting construction durations led to the identification
of some major causes of construction project delays. Both the questionnaire survey results in Hong
Kong and the review of recent relevant research revealed the significance of non-scope contributors
such as project participant priorities and relationships. Such contributors affect project durations both
directly, and indirectly through their effects on productivity levels.
For example, the questionnaire survey indicated the perceived importance of the impact on
construction delays of the contractor-related, design-team-related and labour-related factor
categories. The particular contribution of variable productivity levels to these significant factor
categories was noted, leading to an examination of factors affecting productivity itself and of how
productivity could be considerably enhanced and delays minimized, through techniques such as work
study. Another aspect of consistently increased productivity levels, although not explored in this paper,
is the possibility of reductions in the planned project durations themselves, in the first instance. An
integration of these findings with those from the previous phases of the ongoing study (Chan and
Kumaraswamy, 1995) confirms that productivity is one of the key factors in determining both planned
and achieved project durations, and that while project scope factors must be used to model the
planned project durations, other non-scope factors need to be incorporated in the model, in setting the
baselines and in adjusting for particular priorities, capabilities and motivations of the interacting project
participants.
The questionnaire survey in this investigation also revealed differences in perceptions as to causes of
delays by different groups of project participants: clients, consultants and contractors in building works
as well as in civil engineering works. It is suggested that these apparent collective biases of different
industry groups may often direct blame for delays to other groups, and discourage a search for the
root causes of delays and solutions to same. The origin of such biases may be traced to group
conditioning, as well as to the present adversarial nature of the contractual systems, including the
clashes, blame allocation and defensive postures induced by the not uncommon 'extension of time'
claims and associated costs in construction contracts.
Studies on causes of project delays must thus make allowances for such biases when verifying the
real reasons, whether through interviews or through selected project documents. Furthermore, special
efforts must be made to overcome such biases, as well as to analyse and address the factors and
factor categories identified in this study and the literature, as significant contributors to project delays.
Particular strategies may be designed to address the significant factors, such as unforeseen ground
conditions, poor site management and supervision, and delays in design information. As a general
principle, for example, more intensive site investigations and stronger management are probably
warranted in projects where delays can be crucial. Of course, such principles need to be translated
into practice through appropriate guidelines and project-specific procedures.
This study thus provides pointers to appropriate strategies and particular measures that may be
adopted to avoid and/or mitigate project delays by focusing on the direct and indirect common
contributors to same, such as delays in design information and productivity levels. While the present
survey was based in Hong Kong, the international literature revealed general similarities that may merit
detailed comparative investigations elsewhere.
Table 1 Percentage of time overruns in the three project samples in the previous survey in Hong Kong
Legend for Chart:
A - Actual percentage of time overrun
B - Government building projects (%)
C - Private building projects (%)
D - Civil engineering projects (%)
A B C D
0 40 25 34
1-10 27 28 21
11-20 11 17 21
21-30 14 11 13
31-40 5 1 15
41-50 3 0 3
>50 0 8 3
Mean percentage of time overrun 9 17 14
Sample size 37 36 38
Table 2 Contractors' responses and ranking of the significance of factors causing delays in building
projects (sample size = 27)
Legend for Chart:
A - Hypothesized factors (1)
B - Percentage of respondents scoring: >/=4 (2)
C - Percentage of respondents scoring: 3 (3)
D - </=2 (4)
E - Relative importance index (5)
F - Rank (6)
A B C
D E
F
Delays in design information 88.89 7.41
3.70 0.889
1
Long waiting time for approval
of drawings 85.19 11.11
3.70 0.822
2
Poor site management and supervision 81.48 14.82
3.70 0.822
3
Unrealistic contract durations
imposed by client 75.00 25.00
0.00 0.817
4
Mistakes and discrepancies
in design documents 81.48 14.82
3.70 0.815
5
Long waiting time for approval
of test samples of materials 77.78 18.52
3.70 0.815
6
Inappropriate overall
organizational structure
linking all project teams 66.67 29.63
3.70 0.807
7
Inadequate design team experience 81.48 11.11
7.41 0.8
8
Lack of communication between
consultant and contractor 74.07 22.23
3.70 0.8
9
Low speed of decision making
involving all project teams 74.07 14.82
11.11 0.8
10
Delays in subcontractors' work 69.23 26.92
3.85 0.792
11
Inadequate contractor experience 62.96 33.34
3.70 0.785
12
Necessary variations 74.07 22.23
3.70 0.778
13
Disputes/conflicts 77.78 14.81
7.41 0.770
14
Low speed of decision making
within each project team 70.37 22.22
7.41 0.770
15
Lack of communication between
client and consultant 66.67 22.22
11.11 0.770
16
Shortage of materials in markets 62.96 25.93
11.11 0.770
17
Client-initiated variations 74.07 22.23
3.70 0.763
18
Unforeseen ground conditions 66.67 25.92
7.41 0.756
19
Slow information flow between
project team members 62.96 37.04
0.00 0.756
20
Table 3 Consultants' responses and ranking of the significance of factors causing delays in civil
engineering projects (sample size = 25)
Legend for Chart:
A - Hypothesized factors (1)
B - Percentage of respondents scoring: >/=4 (2)
C - Percentage of respondents scoring: 3 (3)
D - </=2 (4)
E - Relative importance index (5)
F - Rank (6)
A B C
D E
F
Unforeseen ground conditions 80.00 12.00
8.00 0.816
1
Inadequate contractor experience 80.00 16.00
4.00 0.8
2
Poor site management and supervision 68.00 28.00
4.00 0.792
3
Inappropriate type of foundations 78.26 13.04
8.70 0.791
4
Low speed of decision making
involving all project teams 75.00 12.50
12.50 0.783
5
Necessary variations 72.00 24.00
4.00 0.776
6
Client-initiated variations 76.00 16.00
8.00 0.768
7
Deficiencies in planning and scheduling
at preconstruction stage 72.00 12.00
16.00 0.76
8
Unsuitable leadership style of
contractor's construction manager 68.00 20.00
12.00 0.76
9
Improper control over site
resource allocation 56.00 36.00
8.00 0.76
10
Slow information flow between
project team members 70.83 16.67
12.50 0.758
11
Shortage of plant/equipment 68.00 20.00
12.00 0.752
12
Unsuitable management structure
and style 68.00 20.00
12.00 0.752
13
Low speed of decision making within
each project team 62.50 33.33
4.17 0.75
14
Inadequate managerial skills 64.00 28.00
8.00 0.736
15
Shortage of skilled labour 60.00 32.00
8.00 0.736
16
Inappropriate type of main construction 70.83 20.83
8.34 0.733
17
Small extent of design information
available at construction start 66.66 16.67
16.67 0.733
18
Shortage of managerial and supervisory
personnel 72.00 12.00
16.00 0.728
19
Delays in subcontractors' work 60.00 32.00
8.00 0.728
20
Table 4 Relative importance indices (RII) of the ten most significant factors causing delays in building
works (in descending order of significance)
Legend for Chart:
A - Hypothesized factor
B - Factor category
C - Clients (RII)
D - Consultants (RII)
E - Contractors (RII)
F - Weighted average
A
B C D
E F
Poor site management and supervision related
Contractor 0.800 0.858
0.822 0.825
Unforeseen ground conditions
Project related 0.763 0.842
0.756 0.814
Delays in design information
Design team related 0.689 0.742
0.889 0.775
Lack of communication between
consultant and contractor
Project related 0.741 0.783
0.8 0.774
Inadequate contractor experience
Contractor related 0.763 0.765
0.785 0.771
Low speed of decision making
involving all project teams
Project related 0.733 0.808
0.800 0.761
Client-initiated variations
Client related 0.741 0.808
0.763 0.757
Necessary variations of works
Project related 0.756 0.783
0.778 0.756
Delays in subcontractors's work
Contractor related 0.708 0.767
0.792 0.755
Improper control over site
resource allocation
Contractor related 0.769 0.775
0.719 0.754
Table 5 Relative importance indices (RII) of the ten most significant factors causing delays in civil
engineering works (in descending order of significance)
Legend for Chart:
A - Hypothesized factor
B - Factor category
C - Clients (RII)
D - Consultants (RII)
E - Contractors (RII)
F - Weighted average
A
B C D
E F
Unforeseen ground conditions
Project related 0.826 0.816
0.8 0.814
Poor site management and supervision
Contractor related 0.878 0.792
0.710 0.796
Low speed of decision making
involving all project teams
Project related 0.755 0.783
0.743 0.761
Client-initiated variations
Client related 0.757 0.768
0.743 0.757
Necessary variations of works
Project related 0.678 0.776
0.733 0.756
Inadequate contractor experience
Contractor related 0.817 0.8
0.632 0.755
Unsuitable management structure
and style of contractor
Contractor related 0.773 0.752
0.7 0.743
Contractor's deficiencies in planning
and scheduling at preconstruction stage
Contractor related 0.8 0.76
0.648 0.739
Shortage of managerial and supervisory
personnel
Contractor related 0.765 0.728
0.695 0.730
Unsuitable leadership style of
contractor's construction manager
Contractor related 0.752 0.76
0.67 0.730
Table 6 Relative importance indices (RII) and ranks (R) for different factor categories, and by different
survey respondents in the building works grouping
Legend for Chart:
A - Factor category
B - Client: RII
C - Client: R
D - Consultant: RII
E - Consultant: R
F - Contractor: RII
G - Contractor: R
H - Weighted average: RII
I - Weighted average: R
A B C D
E F G
H I
Project related 0.588 6 0.645
4 0.672 5
0.635 5
Client related 0.572 8 0.609
7 0.649 7
0.610 8
Design team related 0.641 3 0.677
3 0.778 1
0.700 2
Contractor related 0.708 2 0.711
1 0.699 3
0.706 1
Materials 0.606 4 0.600
8 0.681 4
0.630 6
Labour 0.717 1 0.682
2 0.662 6
0.687 3
Plant/equipment 0.577 7 0.636
5 0.634 8
0.615 7
External 0.598 5 0.632
6 0.746 2
0.660 4
Table 7 Relative importance indices (RII) and ranks (R) for different factor categories, and by different
survey respondents in the civil engineering grouping
Legend for Chart:
A - Factor category
B - Client: RII
C - Client: R
D - Consultant: RII
E - Consultant: R
F - Contractor: RII
G - Contractor: R
H - Weighted average: RII
I - Weighted average: R
A B C D
E F G
H I
Project related 0.619 4 0.646
4 0.615 5
0.628 5
Client related 0.526 7 0.610
7 0.571 7
0.570 7
Design team related 0.639 3 0.681
2 0.677 1
0.666 2
Contractor related 0.701 1 0.701
1 0.632 4
0.680 1
Materials 0.520 8 0.591
8 0.555 8
0.556 8
Labour 0.665 2 0.680
3 0.643 3
0.665 3
Plant/equipment 0.604 6 0.645
5 0.574 6
0.610 6
External 0.605 5 0.618
6 0.672 2
0.630 4
Table 8 Cross-comparison of the relative importance of the ten most significant factors causing
delays as perceiver by the different groups of respondents
Legend for Chart:
A - Project participant
B - Rank agreement factor: Building
C - Rank agreement factor: Civil
D - Percentage agreement: Building
E - Percentage agreement: Civil
A B C D E
Clients and consultants 2.0 2.6 60 48
Consultants and contractors 3.4 2.4 32 52
Clients and contractors 4.2 3.6 16 28
Table 9 Cross-comparison of the relative importance of factor categories causing delays as
perceived by the different groups of respondents
Legend for Chart:
A - Project participant
B - Rank agreement factor: Building
C - Rank agreement factor: Civil
D - Percentage agreement: Building
E - Percentage agreement: Civil
A B C D E
Clients and consultants 1.50 0.50 62.5 87.5
Consultants and contractors 2.50 1.25 37.5 68.75
Clients and contractors 1.75 1.25 56.25 68.75
Table 10 The six common significant factors from both building works and civil engineering works
Factor Factor category
Unforeseen ground conditions Project related
Poor site management and Contractor related
supervision
Low speed of decision making Project related
involving all project teams
Client-initiated variations Client related
Necessary variations of works Project related
Inadequate contractor experience Contractor related
GRAPH: Figure 1 Comparison of the relative importance indices (RIIs) of the factors considered most
significant by clients, consultants and contractors of building works (as in Table 4): 1. poor site
management and supervision; 2. unforeseen ground conditions; 3. delays in design information; 4.
lack of communication between consultant and contractor; 5. inadequate contractor experience; 6.
Low speed of decision making involving all project teams; 7. client-initiated variations; 8. necessary
variations of works; 9. delays in subcontractors' work; 10. improper control over site resource
allocation
GRAPH: Figure 2 Comparison of the relative importance indices (RIIs) of the factors considered most
significant by clients, consultants and contractors of civil engineering works (as in Table 5): 1.
unforeseen ground conditions; 2. poor site management and supervision; 3. low speed of decision
making involving all project teams; 4. client-initiated variations; 5. necessary variations of works; 6.
inadequate contractor experience; 7. unsuitable management structure and style of contractor; 8.
contractor's deficiencies in planning and scheduling at preconstruction stage; 9. shortage of
managerial and supervisory personnel; 10. unsuitable leadership style of contractor's construction
manager
GRAPH: Figure 3 Percentage agreement (PA) between different groups as to (a) factors and (b) factor
categories contributing to project delays; based on Tables 8 and 9 respectively
References
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Appendix 1: First page of five-page questionnaire for research project SECTION A: GENERAL
ORGANIZATION INFORMATION
Date information collected
Name of organization
Major type of work involved (e.g. buildings, roads or others)
Contact person and designation
Relevant working experience year(s)
Contact address
Contact phone No. Contact Fax. No.
SECTION B: FACTORS INCREASING CONSTRUCTION DURATIONS OF PROJECTS
COMPLETED DURING 1990-1994 IN HONG KONG
Please indicate the significance of each factor by ticking the appropriate boxes. Add any remarks
relating to each factor on the last column e.g. as to the reasons, the critical factors or the solutions.
E.S. = extremely significant (100)
M.S. = moderately significant (50)
N.S. = not significant (0)
V.S. = very significant (75)
S.S. = slightly significant (25)
Hypothesized E.S. V.S. M.S. S.S. N.S. Remarks
factors (100) (75) (50) (25) (0)
1. Project-related
factors
Necessary variations
Inappropriate type of
contract used (e.g.
traditional,
design-and-build, etc.)
Type of project
(e.g. building or civil)
End use of product
(e.g. housing, office or
bridge)
Work type (e.g. new,
refurbished, mixed, etc.)
Large gross floor area
of building
Appendix 2: Distribution profile of respondents to the survey questionnaire
Legend for Chart:
A - Project category
B - Clients
C - Consultants
D - Contractors
E - Total
A B C D E
Building works 27 24 27 78
Civil works 23 25 21 69
Total 50 49 48 147
Appendix 3: Work experience profile (in years) of respondents to the survey questionnaire
Legend for Chart:
A - Project category
B - Clients
C - Consultants
D - Contractors
E - Mean
A B C D E
Building works 15.2 15.0 13.2 14.4
Civil works 13.9 17.4 18.8 16.7
~~~~~~~~
By Mohan M. Kumaraswamy and Daniel W. M. Chan
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