Assessment of cost overrun factors in construction projects in Nigeria using fuzzy logic

The evaluation of cost overrun factors were carried out in this research study using fuzzy logic soft computing tool to analyze survey reports from professionals and expert in the construction industry. Due to value engineering underestimating of the actual cost during cost budgeting, cost overrun results in experienced costs exceeding the budgeted amount. Through relevant literature and thorough investigative study, the cost overrun factors were uncovered and structured in a questionnaire design. This investigative study was carried out on building project contractors, consultants and project managers in Nigeria. The obtained results from survey report indicated Poor communication among stakeholders and Contractor’s financial constraints were the most severe factors causing cost overruns with SI of 4.29. The model development was carried using the survey results in MATLAB software, and the processing parameters are: Mamdani fuzzy inference system type, maximum and minimum function for aggregation and implication, respectively, centroid method of defuzzification, membership function parameters: trapezoidal, triangular and Gaussian. Fuzzy logic model performance evaluation was further achieved producing mean absolute percentage error, root mean square error and coefficient of determination of 0.115%, 0.321 and 0.995, respectively. The results showed good connection between the actual and fuzzy logic model estimated results which indicates good model prediction performance.