Project planning is the process of identifying all the activities necessary to successfully complete the project. Project scheduling is the process of determining the sequential order of the planned activities, assigning realistic duration’s to each activity, and determining the start and finish dates for each activity. Thus, project planning is a prerequisite to project scheduling because there is no way to determine the sequence or start and finish dates of activities until they are identified.
Techniques for Project Planning and Scheduling
The technique used for project planning and scheduling will vary depending upon the project’s size, complexity, duration, personnel, and owner requirements. The project manager must choose a scheduling technique that is simple to use and is easily interpreted by all project participants. There are two methods that are commonly used in project management for the purpose of project planning and scheduling: the bar chart (sometimes called the Gantt chart) and the Critical Path Method (sometimes called CPM or Network Analysis System).
The bar chart, developed by Henry. L. Gantt during World War I, is a graphical time-scale of the schedule. It is easy to interpret; but it is difficult to update, does not show interdependence’s of activities, and does not integrate costs or resources with the schedule. It is an effective technique for overall project scheduling, but has limited application for detailed construction work because the many interrelationships of activities, which are required for construction work, are not defined. Many project managers prefer the bar chart for scheduling engineering design work because of its simplicity, ease of use, and because it does not require extensive interrelationships of activities. However, it can require significant time for updating since the interrelationships of activities are not defined. A change in one activity on the bar chart will not automatically change subsequent activities. Also, the bar chart does not integrate costs with schedule, not does it provide resources, such as labor-hours, that are important for management of design.
The Critical Path Method (CPM) was developed in 1956 by the DuPont Company, with Remington Rand as consultants, as a deterministic approach to scheduling. The CPM method is commonly used in the engineering and construction industry. A similar method, Program Evaluation and Review Technique (PERT) was developed in 1957 by the US Navy, with Booze, Allen & Hamilton Management Consultants, as a probabilistic approach to scheduling. It is more commonly used by the manufacturing industry; however, it can be used for risk assessment of highly uncertain projects. Both methods are often referred to as a Network Analysis System. The CPM provides interrelationships of activities and scheduling of costs and resources. It is also an effective technique for overall project scheduling and detailed scheduling of construction. However it does have some limitations when applied to detail engineering design work during early stages of a project because it requires an extensive description of the interrelationships of activities.
Although the CPM technique requires more effort than a bar chart, it provides more detailed information that is required for effective project management. Using a network schedule to plan a project, the project team is forced to break a project down into identifiable tasks and to relate the tasks to each other in a logical sequence in much greater detail than a bar chart. This up-front project planning and scheduling helps the project team to identify conflicts in resources before they occur.