工程造价外文文献

INHIBITING FACTORS AND MITIGATING MEASURES IN PRACTICE

Yakubu Adisa Olawale, Ph.D., MCIOB and Ming Sun, Ph.D. (Professor)

Abstract

Despite the availability of various control techniques and project control software many construction projects still do not achieve their cost and time objectives. Research in this area so far has mainly been devoted to identifying causes of cost and time overruns. There is limited research geared at studying factors inhibiting the ability of practitioners to effectively control their projects. To fill this gap, a survey was conducted on 250 construction project organisations in the UK, which was followed by face-to-face interviews with experienced practitioners from 15 of these organisations. The common factors that inhibit both time and cost control during construction projects were firstly identified. Subsequently 90 mitigating measures have been developed for the top five leading inhibiting factors - design changes, risks/uncertainties, inaccurate evaluation ofproject time/duration, complexities and non-performance of subcontractors were recommended. These mitigating measures were classified as: preventive, predictive, corrective and organisational measures. They can be used as a checklist of good practice and help project managers to improve the effectiveness of control of their projects.

Keyword: Cost control, interview, practice, project control, project

management,

INTRODUCTION

In the construction industry, the aim of project control is to ensure the projects finish on time, within budget and achieving other project objectives. It is a complex task undertaken by project managers in practice, which involves constantly measuring progress; evaluating plans; and taking corrective actions when required (Kerzner, 2003). During the last few decades, numerous project control methods, such as Gantt Bar Chart, Program Evaluation and ReviewTechnique (PERT) and Critical Path Method (CPM), have been developed (Nicholas 2001, Lester 2000). A variety of software packages have become available to support the application of these project control methods, for example Microsoft Project, Asta Power Project, Primavera, etc. Despite the wide use of these methods and software packages in practice, many construction projects still suffer time and cost overruns. In recent years, there have been numerous studies on the identification of influencing factors of project time and cost overruns worldwide. Mansfield et al (1994) carried out a questionnaire survey amongst 50 contractor, consultant and client organisations in Nigeria and found out that the most important variables causing construction delays and cost overruns are poor contract management, financing and payment of completed works, changes in site conditions, shortage of materials, imported materials and plant items, design changes, subcontractors and nominated suppliers. While the top variables causing only cost overruns were revealed as price fluctuation, inaccurate estimates, delays, additional work. Kaming et al (1997) identified factors influencing construction

time and cost overruns on Cite as: Olawale, Y., and Sun M. (2010). “Cost and time control of construction projects: Inhibiting factors and mitigating measures in practice.” Construction Management and Economics, 28 (5), 509 – 526. high-rise building projects in Indonesia through a questionnaire survey administered on 31 project managers. A total of 11 variables (design changes, poor labour productivity, inadequate planning, material shortages, inaccuracy of material estimate, skilled labour shortage etc) were identified for time overrun and seven (materials cost increased by inflation, inaccurate quantity take-off, lack of experience of project location, lack of experience of project type etc) for cost overrun. Kumaraswamy and Chan (1998) conducted a more extensive study in Hong Kong using 400 questionnaires after which follow up interviews were held. The study revealed the top ten causes of construction delays from the contractors’ point of view as delays in design information, long waiting time for approval of drawings, poor site management and supervision, mistakes and discrepancies in design documents, etc. Similar survey studies were reported by Frimpong et al (2003) in Ghana and by Assaf and Al-Hejji (2006) in Sandi Arabia. In addition to questionnaire surveys, other researchers adopted a case study approach. Al-Momani (2000) examined 130 public projects in Jordan and concluded that the main causes of delays include changes initiated by designers, client requirement, weather, site conditions, late deliveries, economic conditions, etc. Hsieh et al (2004) conducted a statistical analysis in 90 metropolitan public work projects in Taiwan and identified problems in planning and design as main causes of change orders. Yogeswaran et al (1998) scrutinised 67 civil engineering projects in Hong Kong and suggested that at least a 15-20% time overrun was due to inclement weather. Based on analysis of 46 completed building projects in the UK, Akinsola et al (1997)

identified and quantitatively examined factors influencing the magnitude and frequency of

Cite as: Olawale, Y., and Sun M. (2010). “Cost and time control of construction projects: Inhibiting factors and mitigating measures in practice.” Construction Management and Economics, 28 (5), 509 – 526. variations in building projects. These factors include: client characteristics, especially lack of prior experience and knowledge of construction project organization and the production processes; project characteristics, such as type, size, complexity and duration of the project; and project organisation factors, such as; design duration, percentage of design completed before tender, procurement and contract type, adequacy of information provided, and number of sub-contractors. While all the above studies, to various extents, helped with the better understanding of the problems associated with cost and time overruns in construction projects, there are some limitations. (1) Some of these studies are over 10 years old. There is a need for a more up to date investigation to reflect any development in recent years. (2) Most of the studies were carried out outside the UK. Although construction projects worldwide share some common characteristics, there are also some country specific conditions. For example, it is highly unlikely that “shortage of materials” and “import of materials” are major factors in the UK. Therefore, a UK based study will help to identify issues most relevant to the contemporary practice in this country. (3) Some of the reviewed surveys had relatively small sample sizes, which may affect the reliability of their results. (4) All the studies focused on identifying factors that have the biggest influence on project costs and time. They did not discuss the degrees of difficulty in controlling these factors in practice. There

seems to be an implicit assumption that the most important factors are also those most difficult to control. This needs to be explicitly validated. (5) Finally, most existing studies stopped at the identification of the influencing factors, but did not progress Cite as: Olawale, Y., and Sun M. (2010). “Cost and time control of construction projects: Inhibiting factors and mitigating measures in practice.” Construction Management and Economics, 28 (5), 509 – 526. onto finding ways of mitigating the identified problems. These observations underlie the rationale for this study. Its aim is to identify the main inhibiting factors of project control in practice in the UK and then to develop some mitigating measures to assist project managers better control their projects.

RESEARCH METHODS

This research adopts a combination of quantitative and qualitative methods. It was conducted in two stages. The first stage was conducted using a quantitative method through a questionnaire survey in a bid to generate information from a large sample population. The second stage of the study was conducted using the qualitative method using semi-structured interviews. The reasons for using the interview in addition to the questionnaire survey were: to triangulate data obtained from the questionnaire survey; to enhance, expand and create depth to the results of the questionnaire survey by investigating and elaborating on some of the issues highlighted; and to explore the experiences of the sample population in relation to the topical issues revealed after analysis of the data obtained from the questionnaire survey.

Questionnaire Survey

The aim of the survey is toestablish the current common practice of time and cost control in the UK construction industry, including control methods and software applications being used by practitioners as well as inhibiting factors. It started with a thorough review of existing studies that revealed a lot of issues on construction Cite as: Olawale, Y., and Sun M. (2010). “Cost and time control of construction projects: Inhibiting factors and mitigating measures in practice.” Construction Management and Economics, 28 (5), 509 – 526. project time and cost overruns, project control tools and techniques and latest thinking and new developments in the field of construction project control. This led to the development of a questionnaire made up of 22 multiple choice questions. The questionnaire was divided into three sections:

Section one was background information which was targeted at obtaining information on the general particulars of the respondents and their organisation, such as the experience ofthe respondnets, their position within the organisation, the type of project embarked on by the organisation etc.

The second section was about time overrun, project planning and time control practice such the frequency of time overrun experienced, the techniques used for planning and time control, the factors that hampers respondents from effectively controlling their projects etc .

while the third section contained similar questions but specific to cost

control practices. A total of 250 questionnaires were administered; 150 to the top construction companies in the UK by company turnover and the remaining 100 to the top construction project consultancies in the country by the number of professional staff employed and company fee earnings. This list was obtained from the Building magazine annual league tables. The league tables did not contain the addresses of the companies so an online web search was conducted to find their addresses and contact details. Telephone calls were subsequently made to these companies to confirm the addresses and to find out the type of hierarchy and structure that exists within the organisation. This enabled the questionnaires to be sent to the appropriate Cite as: Olawale, Y., and Sun M. (2010). “Cost and time control of construction projects: Inhibiting factors and mitigating measures in practice.” Construction Management and Economics, 28 (5), 509 – 526. department. To supplement this, the name of a construction director, manager or the appropriate personnel with a huge responsible for the management of construction projects in the organisation was obtained to ensure that the questionnaires went to the correct addresses and addressed to the appropriate personnel. This ensured a very good response as 110 questionnaires (44% response rate) were returned. Tables 1 and 2 show the profile of the practitioners that responded to questionnaire on behalf of their companies. Nearly 72% of the respondents that completed the questionnaires were directors or senior managers, commercial managers. As would be expected from their roles, these respondents also had significant years of experience in the construction industry. Nearly half (48%) of respondents had more than 25 years of experience. This showed that there was great depth in the experience possessed by the respondents.

DISCUSSIONS

This study approached the influencing factors of project control from a new perspective. As previously mentioned a lot of previous studies in the area of project control have mainly been focused at cost and time overruns most especially their causes. Their findings are often influenced by the specific context of each study. Many researchers came up with quite different lists of top factors that have major impact on cost and time. The survey results of this study reflect the current views of the leading practitioners in the UK. Another aspect that distinguishes this study from previous ones is that the survey during the first stage of the study seeks to identify the main factors that hamper project managers’ ability to control cost and time not just those that might have the biggest impact. It is interesting to find that the top five inhibiting factors are all project internal elements. This is in contrast to previous studies where many external aspects are often cited as most important factors, such as inflation, material shortage, unforeseen ground conditions, inclement climate, etc. Cite as: Olawale, Y., and Sun M. (2010). “Cost and time control of construction projects: Inhibiting factors and mitigating measures in practice.”Construction Management and Economics, 28 (5), 509 – 526. (Arditi, 1985; Kaming et al, 1997; Mansfield et al, 1994, Kumaraswany and Chan, 1998). The possible explanation for this is that although external factors are usually difficult to control or even beyond the control of project managers, the frequency of their occurrence is general low. On the other hand, internal factors are persistent and

require constant controlling.

The mitigating measures are distilled from in-depth interviews with very experienced project management practitioners. They are not simply selected from current best practice. They reflect what should be done to improve the current project control practice. For example in-depthinterviews found that there has been a general decline in the production of detailed design for construction projects; and this is perceived as one of the greatest cause of design changes, the foremost bottleneck during the project control process. It was also revealed that there is often a lack of distinction between a design change and a design development leading to argument among project partners. In-depth interviews also brought to light the fact clients contribute to the problem of project cost and time control by imposing unachievable and unrealistic time scales. These revelations led to the development of a number of mitigating measures, some of the measures developed on the back of these problems include; measures 8 (designing the project to a great detail at the outset whenever possible), 1 (clear distinction between a design change and a design

development at the outset of a project), 37 (educating and advising client on alternative if an unachievable/unrealistic project timescale is stipulated), 38 (having the courage to refuse unrealistic project timescale by clients unwilling to yield to Cite as: Olawale, Y., and Sun M. (2010). “Cost and time control of construction projects: Inhibiting factors and mitigating measures in practice.” Construction Management and Economics, 28 (5), 509 – 526. professional advise). It was also revealed that quite often, the non-performance of subcontractorsis not necessarily the fault of subcontractors but due to lack of effective management by the main contractor. The mitigating measures that stemmed from this include; 66

(properly directing the subcontractor to ensure they know what is expected of them in relation to the project), 68 (putting a system in place for early identification of non-performance in subcontract works/packages in order to nip it in the bud as soon aspossible) and 69 (utilising performance measurements e.g. S-curve, KPI to monitor the output/performance of subcontractors on their work package). The development of the mitigating measures was also built on the existing studies on good but often generic project management practices. For example several previous studies revealed that the wooly area of design change and design development is one of the key reasons why design change is considered a barrier to effective cost and time control. To combat this, Kartam et al (2000) recommended that end user requirement should be closely coordinated in the early phase of the project and more attention should be placed on managing this requirement during the construction

phase. This is similar to some of the mitigating measures identified in this study but this study has gone further by making them more specific to the project control process. For example measures 8, 15 and 18 in table 12 have been made specific for mitigation of design changes during the project control process. Another mitigating measure for design change is measure 11 (agreeing and putting in place change management procedure before the commencement of projects, incorporating this Cite as: Olawale, Y., and Sun M. (2010). “Cost and time control of construction

projects: Inhibiting factors and mitigating measures in practice.” Construction Management and Economics, 28 (5), 509 – 526. into the contract if

possible). This measure was also buttressed by a number of studies in different ways. For example Lee et al (2005) identified project change

management as a critical practice that has important impacts on both cost and schedule performance or projects. Ling etal (2009) in the study of key project management practices affecting project performance found that the most significant practices that are significantly correlated with project performance relate to scope management and recommended that emphasis must be given to scope management in order to achieve superior project performance. Similarly Zou and Lee (2008) used multiple one-way ANOVA and linear regression to investigate the effectiveness of change management practices elements in controlling project change cost and found amongst others that using change management practices is truly helpful in lowering the proportion of change cost in project actual cost. On another hand, Kog et al (1999) identified key determinants for construction schedule performance and discovered amongst others, that havinga constructability programme is a key determinant to construction schedule performance. A constructability programme was described in the study as the application of a disciplined and systematic optimisation of construction-related knowledge during the planning, design procurement and construction stages by knowledgeable experienced construction personnel who are part of the team. Measures 34, 35, 36 and 42 in table 14 developed for the mitigation of inaccurate evaluation of project time duration are specific practices that will go a long way at ensuring the development of a constructability programme. Cite as: Olawale, Y., and Sun M. (2010). “Cost and time control of construction projects: Inhibiting factors and mitigating measures in practice.” Construction Management and

Economics, 28 (5), 509 – 526. The mitigating measures are the result of a three staged research process. It will be wrong to assume that these measures are identified from only a small number of interviews. In fact, the interview is just the last stage of the development of these measures in a three stage process involving, literature review, questionnaire survey, intellectual thinking and finally the interviews which acted as a way of putting some practicalityin the mitigating measures by drawing from the real life experiences of interviewees. It should also be pointed out that the interviews did not ask practitioners about their experience of a single project or a single company but drew on their experiences of many projects they have worked on. This approach has been adopted by related studies such as Kartam et al (2000), Gao et al (2002) and Sohail et al (2002). For example Sohail et al (2002) in the research aimed at developing monitoring indicators for urban micro contracts began by studying archival records of projects, then used a questionnaire survey to generate more data, conducted interviews to gain more in-depth understanding of the of the situation after which the monitoring indicators were eventually developed by inferences made from analysis of interviews, archival records and questionnaires. While these mitigating measures can contribute to the improvement of project control in practice, there are also some limitations. There is a need for integrating the implementation of these measures into project control models. Some of these measures outline what need to be done, but do not address how they can be achieved. Issues like these need to be investigated in future research. Cite as: Olawale, Y., and Sun M. (2010). “Cost and time control of construction projects: Inhibiting factors and mitigating measures in practice.” Construction Management and Economics, 28 (5), 509 – 526.

CONCLUSIONS

A combination of questionnaire survey and in-depth interviews has been used to provide useful information on issues surrounding project control in practice in the UK. Issues such as the degree of application of project controls, the most commonly used time and cost control techniques, supporting software packages, frequency of time and cost overrun, the leading inhibiting factors to effective cost and time control, the reasons for this and measures that can be used for their mitigation were brought to light.

The top five factors inhibiting time and cost control in construction practice in the UK was revealed as design changes, risks and uncertainties; inaccurate evaluation of project time/duration; complexity of works and; non-performance of subcontractors. Design change is the single most important factor considered by practitioners as hindering the ability to control not only time of construction projects but also cost. In fact, it is found that there is a high level correlation between the inhibiting factors for cost control and time control. Following the identification of the inhibiting factors, 90 mitigating measures are established to address potential problems caused by the top five inhibiting factors. The measures can be broadly classified as preventive, predictive, corrective and organisational measures. These measures are by no means exhaustive as there will obviously be numerous practices out there that have not made the list. It is also worth noting that the measures may seem obvious to the experienced practitioner but will be useful to the less experienced and people new to the project management profession. The study should be viewed as the first Cite as: Olawale, Y., and Sun M.

(2010). “Cost and time control of construction projects: Inhibiting factors and mitigating measures in practice.” Construction Management and Economics, 28 (5), 509 – 526. effort of developing solutions for mitigating leading cost and time control inhibiting factors. Clearly, further development is needed to cover more inhibiting factors beyond the top five. In addition, the effectiveness of these mitigating measures during the project control process needs to be investigated in future research.

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