Precedence Diagramming Method (PDM)

The Precedence Diagramming Method (PDM) is a fundamental tool used in project scheduling for visually depicting the relationships between activities. In PDM, activities are represented as nodes (commonly rectangles), and dependencies between them are shown as arrows connecting these nodes. This method allows project managers to identify the sequence in which activities must be performed, establish the logical relationships, and determine the critical path of the project. There are four types of dependencies utilized in PDM to define the relationships between activities: 1. **Finish-to-Start (FS):** The successor activity cannot start until the predecessor activity finishes. This is the most common type of dependency. 2. **Finish-to-Finish (FF):** The successor activity cannot finish until the predecessor activity finishes. 3. **Start-to-Start (SS):** The successor activity cannot start until the predecessor activity starts. 4. **Start-to-Finish (SF):** The successor activity cannot finish until the predecessor activity starts. This type is rarely used. By employing PDM, project managers can effectively plan and control the project schedule. It facilitates the identification of potential scheduling issues early in the planning process, such as bottlenecks or resource conflicts. Additionally, PDM supports the application of critical path method (CPM) analysis to determine the minimum project duration and identify activities that have flexibility in their scheduling (float). Understanding and utilizing PDM is essential for efficient project scheduling and for communicating the project plan to stakeholders.