Accurate estimation of the activity durations is the most essential element for the effective management of a construction project. Due to the complex conditions existing in the construction environment, there are many influential risk factors associated with an activity. It makes the accurate estimation of activity durations extremely difficult. The most well-known method to deal with such risks has been the Project Evaluation and Review Technique (PERT). In PERT, the different influential risk factors associated with an activity is considered simultaneously by the scheduler to come up with a set of three point estimates (i.e., most-optimistic, most-likely, and most-pessimistic) for the duration of an activity [4]. Although PERT provides a convenient approach to tackle the risks associated with activity duration, it has been criticized to be overly simplified and inaccurate. Using the three point estimates mentioned above, the expected time (t_e) for the duration of an activity can be calculated. The t_e implies the average time the task requires if the task were repeated over an extended period of time. There are several drawbacks associated with the PERT method, such as: historical records are usually not available; most schedulers are not familiar with statistic distribution; Traditional PERT provides only schedule planning but no schedule controlling method, it is difficult to control the risk factors effectively.
展开▼
