Program Evaluation and Review Technique (PERT)
This is required in any case of special projects or large-scale deliveries with a variety of activities. All activities in the project need to be identified accurately, and all must be completed before the project completion. These activities must be initiated and carried out in a specific sequence and must be completed before the start of the completion of other activities. Some activities may occur in parallel, meaning that two or more could be completed at the same time.
In addition, there are specific achievements that indicate the completion of key stages in the project. The successful management of such projects must be carefully planned during implementation of these projects to speed up the delivery during a specified period of time, to coordinate the multi-activity of the project and monitor the use of various resources necessary for its implementation, and to achieve the project on time within the budget cost.
One of the operations research methods, which are used to assist the planning team, the coordination, and the control of such projects special in case of the multiplicity and complexity of activities and the large size project is known as method of Program Evaluation and Review Technique known as PERT.
Although the method of PERT is mainly used for military purposes, it has been used successfully since 1959 for most large-scale projects. PERT analysis is used in a number of areas of the computer industry, construction industries, and in planning the shutdown for maintenance in refineries.
This analysis has confirmed its applicability and importance by its application in different projects. Contracting companies can use it successfully because of its role in solving problems of coordination between various activities in a project that has a considerable degree of complexity and its role in planning the time required for implementing each activity. This method has made it possible to complete a project within the time planned and the overall schedule.
PERT was developed primarily to simplify the planning and scheduling of large and complex projects. It was able to incorporate uncertainty by making it possible to schedule a project while not knowing precisely the details and durations of all the activities.
Hence, the PERT method depends on using statistics and probability theory, so it is now the main key for the project risk assessment from the time schedule point of view.
In some cases, it is required to compress the time schedule, for example, in the oil and gas industry, where time is very critical. This can, however, lead to mistakes. For example, we can start to construct the foundation for a petroleum processing plant before finishing 25% of the engineering deliverables, and this sort of fast tracking often results in rework and usually increases risk.
Any dependencies between activities require specification of a lead or lag to accurately define the relationship. An example of lead in a start-to-finish dependency with 10 days lead is when the successor activity starts 10 days before the predecessor has completed. An example of a lag is when there might be a desire to schedule a 2 week delay (lag) between ordering the equipment and using or installing it.