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2. PHD Thesis / Tesis PHD
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Title:	Causal Models For Predicting Impacts Of Variation Orders (VOS) And Methods Of Control In Roadway Construction Projects Via Structural Equation Modelling (SEM)
Authors:	Towhid Pour Rostam (P49084)
Supervisor:	Amiruddin Ismail, Prof. Engr.Dr.
Keywords:	VOS SEM Roads -- Design and construction
Issue Date:	29-Mar-2013
Description:	There has always been a strong link between the construction industry and variation orders (VOs). In fact, VOs practices, also widely recognized in the Iranian construction industry, are universal phenomena in any project. It should be asserted that the occurrence of unexpected changes is formidable in construction projects, though such changes will yield unruly effects such as project delays, cost overruns and quality degradations. Accordingly, identifying the main causes of VOs would be the first step to unravel VOs problems. To this date, examining the way various causes work together and affect VOs as well as the relationship between the effects has been discarded by the previously conducted studies which had focused on identifying major causes of VOs. Neither have the previous studies dealt with how different methods work together to effects of methods and relationship between the effects in terms of managing. The objectives established in this research include: (i) to identify causes and effects of VOs, analyze their relationships, as well as the relationship between their effects, (ii) to identify the methods of VOs' control, analyze their relationships, as well as the relationship between their effects in roadway construction projects. To fulfil the objectives of this study, after conducting a pilot study in January 2011, and for the purpose of quantitative and qualitative data collection, self-administered questionnaires were distributed in April 2011 among 320 clients, consultants, and contractors who were all involved in roadway construction projects. Overall, 63% of the participants responded to the distributed questionnaire. By using software of SPSS and Analysis of Moment Structure (AMOS), the collected data from the participants was analyzed. The data analyses revealed that time overruns caused by VOs were in the magnitude of 20 to 25% of the original contract value. Nonetheless, schedule overrun was confirmed to be more than 25% of original contract duration. However, the results suggest that all the fit indices satisfy the proposed value range assumed for the two models developed are acceptable. In addition, analytical results indicated clear correlations among key causes of VOs and methods of change order's control which were in fact the bases for solving the future negative effects of VOs. Moreover, the first structural equation model (Cause-Effect of VOs) indicated that out of the three main categories of related causes namely "design and planning phase", "construction phase", and "administration", the construction phase was the main cause for VOs' consequence which included time and cost overrun, and quality degradation. Although the first model proved that time overrun had a positive effect on cost overrun and quality degradation, cost overrun casted a negative effect on quality degradation. The second model (Control-Effect of VOs) revealed that out of the three main categories VOs' control methods which include related control methods on "design and planning phase", " administration" and "construction phase"; the latter proved to be the highest methods of VOs' control. Besides, the second model indicated positive effects of "controlled time" on "controlled cost" and on "improved quality" as well as a positive effect of the "controlled cost" on "improved quality". For empirical testing, the case study methodology was applied and the experts' comments are reported, accordingly. The case study including a document review was conducted for 60 projects among the roadway construction projects in south of Iran from the year 2001 to 2010. The proposed models will be applicable to roadway construction projects in other countries although the study was conducted based on a survey in the Iranian roadway construction projects.,PhD
Pages:	332
Call Number:	TE175 .R647 2013
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Engineering and Built Environment / Fakulti Kejuruteraan dan Alam Bina

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