Theses & Dissertations

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https://hdl.handle.net/20.500.14170/201

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Browsing Theses & Dissertations by Author "Mustafa R R Ghenbasha"
  • Publication
    Structural modeling of variation orders factors and their impacts on performance of roadway construction projects
    ( 2019)
    Mustafa R R Ghenbasha
    The improvement of a country‟s socio-economic development is highly attributed to the construction industry. However, a deep relationship between the variation orders (VOs) and the construction industry has always existed. As a matter of fact, variation orders practices are common in the construction industry of Malaysia- as a universally known phenomenon in all projects. It should be pinpointed that unexpected changes are challenging in the construction projects, despite such changes producing unpleasant effects such as quality degradation, project delays, and cost overruns. As such, the first stage of addressing variation orders issues is the identification of the major causes of variation orders. Previous researches which had concentration on the identification of main causes of variation orders had ignored the investigation of the interdependent relationship between different causes and the way they influence variation orders. Hence, this study focused on developing a structural model of variation orders occurring and determining the most important group that contributes to the occurrence of variation orders as well as determining the influence VOs on project performance. The questionnaire consisted of 36 causative factors which then clustered into 3 groups and 17 effects factors of variation orders which are clustered into 5 groups. These factors and assigned groups were validated by 26 construction personnel (contractors, consultants, and clients) during the pilot study. The actual survey was conducted with a total of 104 questionnaires were received by respond rate of 70%. The data analysis is carried out using software of SPSS; Rasch analysis via WINSTEPS version 3.72.3 software and Smart PLS analysis software. A structural model of occurrence of variation orders was developed based on 3 groups of causative factors and 5 groups of effect factors using Partial Least Squared Structural Equation Modeling (PLS-SEM) technique. It was found that the model is fit due to the R² value of 0.581 (R2 ≥ 0.26 = substantial). The model identifies that all 8 groups are significant with t-value ≥ 2.58 from bootstrapping process of 5000 random samples. The model indicates that a group of "Construction Phase- related factors" has the highest impact on the occurrence of variation orders. Factors related design and planning were considered as the second factors contribute to an occurrence of variation orders in roadway construction projects. While the highest impact of variation orders was on cost performance via "cost overruns". Also, the design planning stage" and "construction stage" has a large negative influence on quality degradation via occurrence of variation. For empirical testing, the case study including a questionnaire survey and collecting secondary data from document review was conducted for 6 projects among roadway construction projects in Penang State completed from 2013 to 2018. This exploratory model gives a better understanding of the occurrence of variation orders in Malaysian roadway projects by explaining the impact load of each factor of cause and effect of variation orders and the relationship among each other