2.4 Project Management in the Mid 20th Century

A more systematic and effective planning techniques were required due to the growing complexity of projects. This resulted in the development of two analytic techniques for planning, scheduling and controlling of projects which are:

		the Critical Path Method (CPM) and
		the Project Evaluation and Review Technique (PERT).

	CPM was first developed by Du Pont Corporation, in 1957, as an application to construction projects and was later extended to a more advanced status by Mauchly Associates.
	PERT was developed by the U.S. Navy by a consulting firm for scheduling the research and development activities for the Polaris missile program in 1958.
	PERT and CPM are basically time-oriented methods in the sense that they both lead to the determination of a time schedule.
	Project scheduling by PERT-CPM consists of three basic phases:

		Planning,
		Scheduling and
		Controlling.

2.4 Project Management in the Mid 20th Century

The planning phase:

		Starts with breaking down the project into distinct activities.
		The time estimates for these activities are then determined and a network (or arrow) diagram is constructed with each of its arcs (arrows) representing an activity.
		The entire arrow diagram gives a graphic presentation of the interdependencies between the activities of the project.
		The construction of the arrow diagram as a planning phase has the advantage of studying different jobs in detail, perhaps suggesting improvements before the project is actually executed. More important will be its use to develop a schedule for the project.

The Scheduling Phase:

		The objective of this phase is to construct a time chart showing the start and finish times for each activity as well as its relationship to other activities in the project.
		In addition, the schedule must identify the critical (in view of time) activities which require special attention if the project is to be completed on time.
		For the non-critical activities, the schedule must show the amount of slack or float times which can be used advantageously when such activities are delayed or when limited resources are to be used effectively.

2.4 Project Management in the Mid 20th Century

The Control Phase:

		It includes the use of the arrow diagram and the time chart for making periodic progress reports.
		The network may thus be updated and analyzed and, if necessary, a new schedule is determined for the remaining portion of the project.