Authors
Abstract
Calculation of Derivations from every objective of the project is very important for both contractors and employers. Time overrun is the function of all project risks. A tool that can assess the risk levels and estimate the derivations from the planed duration is very useful for contractors. This research tries to propose a new methodology to determine the schedule risk of construction projects and the total time overrun. This methodology uses influence diagram to construct the risk model and fuzzy risk assessment system to estimate time overrun for every activity. Then the information of fuzzy risk assessment model is used by scheduling the softwares such as MSP or Primavera to calculate the time overrun of the project. This model has been used in one of the track renewal projects of Iran Railway Administration.
The model was validated by using the estimated data produced by model and the real data of the activities’ duration. Then the mean absolute percentage error (MAPE) was calculated for the activities and the project. MAPE of the activities was equal to 10.75% and the estimated duration of project was equal to 105.24 time unit. In comparison with the real duration of project (which was equal to 113 time units and MAPE for the whole project was equal to 6.7%), it can be concluded that fuzzy risk assessment model has remarkable accuracy to be used in construction projects.
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