Project Scheduling By  PERT - CPM

A project defines a combination of interrelated activities that must be executed in a certain order before the entire task can be completed. The activities are interrelated in a logical sequence in the sense that some activities cannot start until others are completed. An activity in a project is usually viewed as job requiring time and resources for its completion. In general, a project is a one-time effort; that is, the same sequence of activities may not be repeated in the future.

In the past, the scheduling of a project (over time) was done with little planning. The best known "planning" tool then was the Gantt bar chart, which specifies the start and finish times for each activity on a horizontal time scale. Its disadvantage is that the interdependency between the different activities (which mainly controls the progress of the project) cannot be determined from the bar chart. The growing complexities of today's projects have demanded more systematic and more effective planning techniques with the objective of optimizing the efficiency of executing the project. Efficiency here implies effecting the utmost reduction in the time required to complete the project while accounting for the economic feasibility of using available resources.

Project management has evolved as a new field with the development of two analytic techniques for planning, scheduling, and controlling of projects. These are the critical path method (CPM) and the project evaluation and review technique (PERT). PERT and CPM are basically time oriented methods in the sense that they both lead to the determination of a time schedule. Although the two methods were developed independently, they are strikingly similar.

Project scheduling by PERT-CPM consists of three basic phases: planning, scheduling, and controlling. The planning phase is initiated by 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 representation of the interdependencies between the activities of the project. The construction of the arrow diagram as a planning phase has the advantage of studying the different jobs in detail, perhaps suggesting improvements before the project is actually executed.

The ultimate objective of the scheduling 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 pinpoint the critical (in view of time) activities that require special attention if the project is to be completed on time. For the noncritical activities the schedule must show the amount of slack or float times that can be used advantageously when such activities are delayed or when limited resources are to be used effectively.

The final phase in project management is project control. This 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.

The company has strong in-house support facilities to perform project networking on projects related to industrial installations, construction, production management, and general purpose planning for various activities. Software available can provide a wide variety of functions such as tracking submittals, controlling changes, monitoring costs, expediting procurement, daily reports and requisitions, and product specifications.