دوشنبه 29 فروردین 1390


   نوشته شده توسط: عارف محمدی    نوع مطلب :مدیریت منابع سازمانی ،

Another problem with many of the conventional productivity measurement techniques is the reductionistic approach in analysing work time (see e.g. Drewin, 1982). To put simply, much of the analysis of productivity data had been concerned with the binary relationship between productive (or value-adding) time and time loss. However, contenders such as Thomas et. al. (1990) challenged this underlying assumption – the inverse relationship between productive and non-productive time, and that reducing time loss leads to productivity improvements – as they claimed “while these assumptions seem sensible and logical, they will be shown to be unsupportable for most construction operations (p. 712)”. In fact, a later study (Thomas, 1991) provided evidence that would cast doubts on the assumption of the binary relationship between productive and non-productive time, and hence on the productivity measurement techniques.


A further limitation relates to the application of productivity measurement techniques in past research. A review of the literature revealed that measurement techniques were mainly concentrated, in past research, on a number of key construction operations: namely concrete works (Proverbs et. al., 1999; Winch and Carr, 2001), masonry projects (Thomas and Yiakoumis, 1987; Olomolaiye, 1990), structural steel (Thomas and Yiakoumis, 1987) and electrical works (Thomas, 2000). Evidently, with the exception of electrical works, much of the studies were concerned with the structural elements, i.e. elements that contribute to the structural frame of the building. This means there is an overwhelming lack of research aimed at studying such other aspects of the building process as architectural elements (e.g. plastering, internal fit-out, painting and decoration) or services installations (e.g. mechanical and sanitary installations). Indeed, the studies surrounding electrical works were related to the effects of schedule acceleration, in part, due to the effects of productivity-related problems of the earlier structural phase of projects (see e.g. Noyce and Hanna, 1998; and Thomas, 2000). One of the possible reasons for this phenomenon is the lack of previous studies (unlike where areas such as bricklaying and concrete operations are concerned) or industrial productivity data for comparison. Notably, the National Electrical Contractors Association (NECA) in the US has been deeply keen in examining productivity issues ever since the late 1960s (Thomas et. al., 1990) and have been actively developing labour consumption curves (NECA, 1983) to inform the industry for possible applications on different project types (Thomas, 2000), offering perhaps an explanation as to why productivity on electrical projects are examined.


Olomolaiye (1990) is one of the few who explains his decision to focus on bricklaying as he attributed his preference to “the predominance of bricks as one of the main construction materials in the UK”. He added “a bulk of construction manpower still goes into bricklaying as it remains highly labour-intensive (p. 302)”. On the decision to focus on concrete operations, Winch and Carr (2001) cited Horner’s and Zakieh’s (1996) claim that “studies of estimating have shown that the largest items in the bill can be used to determine overall outputs very closely”. Furthermore, they expounded that “data on concrete deliveries by ready-mix trucks for any given period are easily obtained from site records, and because concrete is perishable, we can infer that deliveries on a day have been poured that day (p. 581)”. It is argued, however, that concentrating on the predominant or largest activity results in a reductionistic approach, which fails to take into account the entire construction process. Interestingly, Kazaz and Ulubeyli (2004) in a recent study aimed at reconciling governmental statistics and real project data on productivity rates in Turkey elected to examine only 82 work items deemed to be used most in practice, thus affirming the researcher’s observation, although they acknowledged that these only constitute 6.11% of all possible work items. In this respect, conclusions made in past studies are limited in their scope in offering plausible recommendations for implementation for the improvement of construction labour productivity.

The limitations of productivity measurement techniques discussed hitherto, to some extent, help to explain the low industrial uptake within construction. These encompass the issues of reliability and relevance of existing techniques that would inhibit the ability of companies to meaningfully analyse their project productivity so as to bring about improvements to the entire construction process. Furthermore, there are the investment constraints of time and expertise in implementing the existing productivity techniques. These emerging issues from the brief review explains some of the general difficulties claimed by the participants of the Investors in People (2001) study, particularly the difficulties in obtaining accurate information, the varied nature of individual job roles and the complex nature of productivity that is dependent on several intervening factors (p. 6).



Having briefly discussed the theoretical issues surrounding existing productivity measurement techniques, this section now turns to the two projects, hereinafter known as projects A and B, observed during the course of the study. The purpose of the case studies is to explore the issues faced by practitioners when measuring project productivity. The two projects were selected because project participants had either attempted to measure productivity (project A) or claimed to have a formal method of measuring productivity in place (project B). Each case will begin with a brief synopsis of how the researchers got involved with the projects and an account of the observational process. This will then be followed by a succinct report of the key issues involved in the implementation of the productivity measurement techniques in the two projects.


Project A: Multi-storey Car Park


Background to project A

Project A is the construction of a multi-storey car park for a Scottish airport. This was initially selected as a pilot study at the onset on the basis of convenience, access and geographic proximity as instructed in Yin (1994: 75). It is perhaps worthwhile, at this point, to provide an insight into how and why access was given to this project in the first place. A marketing flyer accompanied by a cover letter was sent to companies to seek collaboration and access to projects, people, data etc. at the start of the research. A positive response from the main contractor executing project A then resulted from this initial call for participation. The contractor was a fast growing company at that time that aimed both to ‘penetrate’ the Scottish construction market and to succeed in gaining repeat business with British Airports Authority (B.A.A.). Because the company had not undertaken any on-site productivity measurement, they were therefore keen for the researchers to assist in the development of on-site productivity measures. And so, access to the project was granted on a two-days-a-week basis and the project quantity surveyor of the company was involved with the researchers in developing the measurement technique.

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