The Critical Path Method ("CPM") of planning and scheduling is the only method that should be utilized for turnarounds. It allows the T/A manager to make judicious decisions based on verifiable logic and criticality (priority) for the tasks involved in the turnaround.

There are many good books available on this time-proven technique and all turnaround planners should be thoroughly familiar with it. The critical path method not only allows you to determine the "critical path" (or sequence of activities which determine the project completion date), but also the overall duration, and any improvements or extensions as the turnaround progresses.

There are two basic methods employed to define the relationship between activities or tasks. They are the Arrow Diagramming Method (ADM) with activity-on-the-arrow, and the Precedence Diagramming Method (PDM) with activity-on-the-work-item. ADM requires a higher degree of activity of definition, and could be slightly more involved to handle due to the node numbering scheme involved. PDM, on the other hand, is more permissible, and easier to manipulate. Both methods are capable of representing the same logic network - ie. they are logically equivalent.