Free Essay On Use Of PERT And Cpm In Project Scheduling
Execution of complex scientific researches, as well as the design and construction of industrial, agricultural and transport facilities, require a large number of calendar linking of interrelated activities carried out by different organizations. Compilation and analysis of relevant schedules are a very difficult task, which solution needs the so-called methods of network planning. Models of network planning and management are designed for planning and management of a complex set of operations (projects), aimed at achieving a certain goal in the given time frame (construction, development and production of complex objects and others).
Network planning and management model is management method in the implementation of a certain set of work (project, program, topics, etc.), based on a network model of the complex, which can significantly improve the quality of planning and managing the implementation of a range of works, in particular makes it possible to precisely coordinate the activities of all parties (organizations) involved in the complex, to highlight the most important tasks, to judge the most appropriate timing of the project and timely adjust implementation plans. The need to use network planning methods in the study of control systems is due to a variety of planning models, namely charts and tables, physical models, logical and mathematical expressions, computer models, simulation models (Stacey, 2011).
PERT method is the method of network analysis, which focuses on the event and is used to estimate the duration of the project at a high measure of uncertainty with the estimates of the duration of a specific job. PERT uses critical path method for weighted estimation of average duration. It is also known as a technology evaluation and analysis program. Weighted averages are used to reduce the uncertainty of unknown duration of works. Critical path method allows calculating the possible schedules of works’ performance on the basis of described logical structure of the network and estimations of the length of each job, and defining the critical path for the project as a whole (Meredith & Mantel Jr., 2011).
In its basic form, the PERT (Рrоgram Evaluation and Review Technique) /CPM (Critical Path Method) method was designed to determine the longest time path in the sequence of operations (critical path), which becomes the basis for planning and monitoring the progress of the project. For graphical display of this sequence arrowed lines and nodes are used. Although PERT and CPM are slightly different in terminology and building a network, they have the same technique. Moreover, the analysis used in both methods is very similar.
First, CPM and PERT differed that in the PERT network chart the operation was reflected by an arrow and in CPM – node (circle). There is another difference: the PERT used three types of activity duration estimates (optimistic, pessimistic, and most likely), and CPM – only the best. These differences are explained by the fact that the PERT method was developed to work with complex projects that are characterized by a high degree of uncertainty, and CPM – for scheduling routine operations associated with the plant maintenance. For many years of the existence of these two methods the differences between them were erased because CPM users have also begun to use three estimates of the duration of operations, and in PERT network charts operations are often designated by nodes.
Application of PERT/CPM scheduling technique is extremely important because it can help to answer questions about the project (Heizer & Render, 2011):
1) When the project will be completed as a whole?
2) What kind of work or tasks are critical in the project?
3) What kind of work is not critical?
4) What is the likelihood that the project will be completed by a specific date?
5) With regard to any date the answer can be received: is the project performed in accordance with the schedule, behind schedule or ahead of schedule?
6) As of any date you can get the answer: is the money spent in accordance with the budget for the project, spent less than the specified funds or costs beyond what is provided by the system?
7) Are there enough resources to complete the project on time?
8) If the project should be completed in a short period of time, what is the way to ensure its completion at the lowest cost?
Currently, network planning techniques can be widely and successfully used to optimize the planning and management of complicated and branched complexes of works that require the involvement of a large number of performers and cost of limited resources. Thus, the main task of the control using the PERT/CPM scheduling techniques in the planning and implementation of projects is not only to identify a particular sequence, where this or that group of works should be performed. With this method it is possible to identify the chain of works, which implementation will require a great time that will allow determining where in the project it is important to do everything possible to avoid the delay of the project. Using the time margin it is possible to “maneuver” the deadlines, avoiding both excessive and insufficient load of operating resources. This allows reducing the total number of involved personnel resources (and sometimes physical – fuel, for example) and save the project budget.
Heizer, Jay & Render, Barry. Operations Management, Global ed., 10th ed. London: Pearson Hall, 2011. Print.
Meredith, Jack R. & Mantel Jr., Samuel J. Project Management: A Managerial Approach. 8th ed., New Jersey: Willey, 2011. Print.
Stacey, Ralph D. Strategic management and organizational dynamics: the challenge of complexity to ways of thinking about organizations. 6th ed., Harlow, England; New York: Financial Times Prentice Hall, 2011. Print.