Risk analysis in construction networks using a modified stochastic assignment model

A review of construction network analysis indicates that new methods are needed for quantifying risks in project evaluation. The paper proposes a new analytical method, the Modified Stochastic Assignment Model (MSAM), for the prediction of project duration. The proposed method is inspired by a previous method used solely in traffic networks, the Stochastic Assignment Model (SAM). The MSAM method applies Clark's approximation to find the longest project duration. Two cases are used to demonstrate the validity and application of the MSAM in construction project evaluations. The accuracy of the MSAM is assessed by comparing it with the Monte Carlo Simulation (MCS). A comparison of the MSAM with other methods, such as PERT and PNET, has also been presented. It is found that the new method is an analytical counterpart of the MCS and is very efficient in saving computational time whilst taking full account of the correlations between paths.