In the project management context, the impotance of risk management is increasing because the risks in terms of time and cost may significantly affect the result of the project. In general, the management of projects schedule risk is achieved by modeling project schedule with PERT/CPM techniques, then performing risk assesment with monte-carlo simulation method. However, these approach can not reflect constraints, which may be occurred during the project execution, and cope with uncertainty in the future. As these constraints may affect time and cost which are the crucial evaluation factor to the project, they must be identified and evaluated to manage the future project risk before the project is started.
This paper proposes a methodology for project schedule risk management by identifying and enforcing the constraints which may be occurred in complex and uncertain project environment. First, project risk constraints are identified and categorized into time, dependancy, and branching. Then, project schedule model with constraints is converted to CPN(Colored Petri Net) which can represent all the identified constraints to assess and predict schedule risk. Finally, the expected risk of the project (in terms of time and cost) is assessed and predicted by performing Petri Net simulation.
By using the methodology proposed in this paper, the risk in terms of time and cost in project schedule model can be assessed and predicted more accurately and practically than the PERT/CPM and/or Monte-carlo simulation method. Furthermore, the constraints, which may occur unexpectedly after the project launch, can be evaluated to determine the schedule risk. The expected risk can be used to decide whether risk mitigation or project termination process undertake.