A Study on The Causes, Cost Effects and Mitigation Measures To Design Error Induced Variation on Selected ERA’s Road Projects
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Date
2020-07
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Addis Ababa University
Abstract
In spite of the scarcity of study on the cost effect of design error induced variation on road
projects, the study has investigated the very causes of design error induced variation, the frequent
design errors that lead to variation, the cost effects of design error on the variation costs, and
mitigations for design error induced variation in selected Ethiopian road projects. A two fold
method of research (Questionnaire survey and Case study road projects) was applied in
collecting the necessary data for the research through a purposive sampling technique. A
specially designed survey questionnaire was distributed and collected from 25 project delegated
respondents to fill out project-specific sections of the questionnaire as well as the industry
generic questions for further analysis. The finding revealed that Inexperience of designers, Lack
of knowledge, Lack of integration/coordination between designers of different disciplines, Design
Cost, and Duration of Design are the top five causes of design error induced variation. The
finding further ranks the frequency of occurrence of design errors based on design elements in the
ordered as Vertical Alignment, Horizontal Alignment, Minor Drainage, and Pavement. Moreover,
out of the total variation cost in road projects, 43% is influenced by design errors with major
contributions of Horizontal Alignment and Minor Drainages Accounting 50% of the cases among
others. Finally, based on the analysis of the results, recommendations have been proposed that
enables to minimize design error which has the potential to result in variation costs.
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Keywords
Cost Overrun, Design Error, Variation Cost, Valuation Documents