Probabilistic method to predict activity duration for critical path method with increased reliability

Critical path method (CPM) is a deterministic technique that has been used extensively for managing projects because of its simplicity compared to other techniques. CPM analyses a project considering resources and time taken to complete each activity based on available data at the time of project planning. However, the predicted activity duration for a similar activity in a similar project will be different with the time, due to advancement in technologies, improved materials and various other factors. This paper reviews available methodologies used to predict activity duration and attempts to introduce probabilistic method to predict the project duration. The method uses simulation technique to generate probability distribution function based on contractor's previous performance on similar project. It enables project manager to detect level of uncertainty on the project duration and how extra resources could be launched with increased confidence to accelerate certain activity to complete the project on time.