Fuzzy inference approach for assessing time related risk factors on highway rehabilitation projects in Nigeria

Construction projects are unique and continuously increasing in complexity. Hence, researchers relied heavily on data collected through expert judgement to assess risks on them. Expert judgement are subjective data, fuzzy and so this paper aimed at exploring the application of Fuzzy set theory for an accurate assessment of risk on Federal highway rehabilitation projects in Nigeria. This study undertakes a comprehensive review of literatures and conducted project specific questionnaire survey of sixteen Federal highway rehabilitation projects and the professionals in the client, construction and consulting firms who are directly involved in the execution of the sampled projects. Data collected were subjected to normalisation and Fuzzy inference analysis. Twelve risk factors are found to be significantly leading to time overrun on highway rehabilitation projects. In addition, Fuzzy inference analysis revealed that interest rate fluctuations and unexpected site conditions made 'Large' contribution to poor performance experienced on the highway rehabilitation projects. This is contrary to the medium impact values derived from normalisation. Hence, the results of this study provide a more accurate database of significant risk factors to local highway contractors and guide the foreign contractors wishing to do construction business in Nigeria on SWOT analysis