Case Study 2:
4.1 Introduction to Case Study
A comparative productivity study has been done between projects that built using pre-cast technology and conventional method. Three project sites are studied: two using pre-cast technology and one using conventional method. The two sites using pre-cast technology are Akademi Binaan Malaysia (ABM) located at Sintok, Kedah and Akademi Audit Negara (AAN) at Nilai, Negeri Sembilan; where as the one using conventional method is SIRIM laboratory located at Bukit Jalil, Selangor. Labor productivity in these three construction methods is studied. The measurements were focused on four structural components: beam, column, wall and slab. Data collected from the sites and reports are analyzed and the actors/indicators that influence the labor productivity are determined.
Construction is a labor-intensive industry especially in the conventional Cast-In-Situ construction method. Although the pre-cast construction method is less labor-intensive, the installation process still requires the labors. Thus, manpower is one of the main factors behind productivity resources in the construction industry.
In ABM and AAN projects, pre-fabricated or pre-cast structural components were installed piece by piece with minimum used of labours, while SIRIM laboratory by using conventional method needs more labours in order to complete the construction cycles for instance, formwork fabrication, reinforcement bar or steel cage fabrication, formwork installation, reinforcement bar installation, concrete placement, and formwork dismantle etc.
Labor efficiency in a project is one of the main factors in productivity. This is because labor efficiency is related to one of the important elements in a project, which is cost. Loss of labor productivity is equivalent to the loss of labor cost that had been paid to the workers. Overall, it can be concluded that loss of labor efficiency of pre-cast project is less than Cast-In-Situ project.
The correlation value of weather, in terms of hours of rain, can be construed as weather is a crucial productivity factor for Cast-In-Situ construction method. At the same time, the value also depicts the trifling effect of weather factor on pre-cast method. Length of workday or overtime is the factor that equally influenced both construction methods.
From the data collected the factor of crew size or number of workers that worked in a group is interpreted as an important factor for Cast-In-Situ project (SIRIM). Yet, it only shows a slight effect on pre-cast projects. Therefore, it can be presumed that number of workers is a crucial factor for Cast-In-Situ method compared to pre-cast method.
Apparently, the factor of delivery and unloading of structural components will only induce poorer productivity in pre-cast construction method. This is due to multi-tasks for the workers or installers, including unloading and installation. Whereas in Cast-In-Situ projects, it only involves raw material deliveries and unloading were taken over by the general workers.
According to contractors from pre-cast and Cast-In-Situ projects, delivery schedule in the planning and management stage is an influential factor for both construction methods. The contractors from the Cast-In- Situ construction sector identically agrees that the factor of material availability, toll or equipment sufficiency and resource allocation in planning and management stage are the determinants of construction site labor productivity. On the other hand, material placement or material storage is considered as the factor for pre-cast construction method. The manufacturing of structural components is only involved in pre-cast construction projects.
During the site installation or construction stage, workspace availability (congestion), instruction and supervision given, work sequencing and location of work are reasons of poor productivity for both pre-cast and Cast-In-Situ construction projects. Besides that the productivity in per-cast construction site is also affected by the causes such as site safety condition, length of workday or overtime and location of work. Furthermore, the contractors from the Cast-In-Situ field felt that the factors of weather, skills of labor, rework, length of work period and location of work displayed higher impact to the productivity values.
From the research that have been done, it can be concluded that the pre-cast method is better than the conventional Cast-In-Situ method in terms of the labor productivity. It can been seen in the number of work hours to install structural components by using pre-cast is less compared to the Cast-In-Situ method.
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- Housing Research Centre, (2) Department of Civil Engineering (3) Department of Mechanical and Manufacturing Engineering, Faculty of Engineering Universiti Putra Malaysia, 43400 UPM Serdang, Malaysia