Faculty of Engineering and Built Environment
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Item Using system dynamics principles for conceptual modelling to resolve causes of rework in construction projects(University of Johannesburg Department of Construction and Quantity Surveying, 2015) Aiyetan, Olatunji Ayodeji; Das, DillipRework in construction projects has brought in two major challenges: cost overruns and delay. In this regards a study was conducted by considering various construction projects in the South West part of Nigeria to understand the causes of rework and the interventions to mitigate it. Survey research methodologies followed by the conceptual system dynamics (SD) modelling were used in the analysis. This study identified the sources of rework in construction projects from the design related, the client related and the contractor related issues and attempted to derive policy/strategic interventions to limit or eliminate rework on construction projects and its delivery by using conceptual SD models based on the influence of the variables on rework. The findings include that inappropriate scheduling for time pressure or delay at the planning stage, lack of adherence to specifications, and non-availability of skilled human resource are the major causes of rework. However, rework in construction projects would be reduced or eliminated through policy interventions, such as, achieving client satisfaction with scheduling for time pressure or delay at the planning stage, adherence to specifications ensuring quality of work resulting in client satisfaction, and the availability of skilled manpower ensuring quality management.Item Resolving contractor commitment challenges in project delivery by using conceptual system dynamics models(University of Johannesburg, 2016) Aiyetan, Olatunji Ayodeji; Das, DillipContractors play a vital role in construction projects. However, their lack of commitment is argued to be one of the major barriers against successful project delivery. This investigation was aimed at to explore how contractor commitment challenges can be resolved to improve their performance in the project delivery. A survey research method was used to collect data, and Likert scale was applied to evaluate the relative importance of the contractor commitment challenges. Followed by conceptual System Dynamics (SD) modelling principle was used to develop causal feedback relationships among the variables influencing contractor commitment and to develop mechanisms to resolve the challenges. Findings suggest that lack of experience, skill, inadequate supervision, and lack of control over the subcontractors lead to contractor’s inefficiency. Poor planning and scheduling, poor professional management, poor execution of projects, ineffective/outdated equipment, and inefficiency of labour force result in poor quality of work and delay. In addition, design and documentation challenges disrupt the contractors’ schedule. The interlinkage among these variables hinders contractor commitment. However, policy/strategic interventions based on the causal feedback relationships among contractor efficiency, and (1) capacity building; (2) professional management; (3) construction methods; and (4) involvement of the contractor and client in the design process would enable the contractors to overcome their challenges to meet their commitment and improve efficiency in project delivery.