Network diagrams are essential visual tools in project management that illustrate the logical sequence and relationships between project activities. In the CompTIA Project+ framework, these diagrams serve as critical documentation for planning, scheduling, and communicating project workflows.
Ther…Network diagrams are essential visual tools in project management that illustrate the logical sequence and relationships between project activities. In the CompTIA Project+ framework, these diagrams serve as critical documentation for planning, scheduling, and communicating project workflows.
There are two primary types of network diagrams used in project management:
1. **Precedence Diagramming Method (PDM)** - Also known as Activity-on-Node (AON), this is the most common format. Activities are represented as boxes or nodes, while arrows show the dependencies between them. PDM supports four dependency types: Finish-to-Start, Start-to-Start, Finish-to-Finish, and Start-to-Finish.
2. **Arrow Diagramming Method (ADM)** - Also called Activity-on-Arrow (AOA), this older method represents activities as arrows connecting nodes. It only supports Finish-to-Start relationships and may require dummy activities to show certain dependencies.
Key benefits of network diagrams include:
- **Critical Path Identification**: By analyzing the diagram, project managers can determine the longest path through the project, which defines the minimum project duration.
- **Dependency Visualization**: Team members can clearly see which tasks must be completed before others can begin.
- **Resource Planning**: Understanding task sequences helps allocate resources effectively throughout the project lifecycle.
- **Schedule Compression**: Network diagrams help identify opportunities for fast-tracking or crashing the schedule when needed.
- **Communication Tool**: They provide stakeholders with a clear visual representation of project flow and complexity.
When creating network diagrams, project managers should identify all activities, determine dependencies, estimate durations, and calculate forward and backward passes to find float or slack time. Modern project management software often generates these diagrams automatically from task lists and dependency information, making them accessible tools for projects of any size.
Network Diagrams - CompTIA Project+ Study Guide
What Are Network Diagrams?
Network diagrams are visual representations of project activities, tasks, and their relationships. They illustrate the sequence of work packages and show how tasks connect to one another, depicting the flow of a project from start to finish. In project management, network diagrams are essential tools for planning, scheduling, and controlling project timelines.
Why Are Network Diagrams Important?
Network diagrams serve several critical purposes in project management:
• Visualize Dependencies: They clearly show which tasks must be completed before others can begin • Identify the Critical Path: They help determine the longest path through the project, which defines the minimum project duration • Resource Planning: They assist in allocating resources effectively across project phases • Schedule Development: They form the foundation for creating realistic project schedules • Risk Identification: They help identify potential bottlenecks and scheduling risks • Communication Tool: They provide stakeholders with a clear visual of project flow
Types of Network Diagrams
Precedence Diagramming Method (PDM) / Activity-on-Node (AON): This is the most common method where activities are represented as boxes (nodes) and arrows show dependencies between them. This method is used by most modern project management software.
Arrow Diagramming Method (ADM) / Activity-on-Arrow (AOA): In this older method, activities are represented by arrows, and nodes represent the start and end points of activities. This method requires the use of dummy activities to show certain dependencies.
How Network Diagrams Work
Key Components: • Nodes: Represent activities or milestones • Arrows: Show the relationship and sequence between activities • Dependencies: Define the logical relationships between tasks
Types of Dependencies: • Finish-to-Start (FS): The most common type - Task B cannot start until Task A finishes • Start-to-Start (SS): Task B cannot start until Task A starts • Finish-to-Finish (FF): Task B cannot finish until Task A finishes • Start-to-Finish (SF): Task B cannot finish until Task A starts (rarely used)
Critical Path Analysis: The critical path is the longest sequence of dependent tasks that determines the shortest possible project duration. Tasks on the critical path have zero float (slack), meaning any delay will extend the project end date.
Float/Slack: Float refers to the amount of time a task can be delayed before it affects the project completion date. Tasks not on the critical path have positive float.
Creating Network Diagrams
1. List all project activities from the WBS 2. Determine the sequence of activities 3. Identify dependencies between tasks 4. Estimate duration for each activity 5. Draw the network showing relationships 6. Calculate early start, early finish, late start, and late finish for each task 7. Identify the critical path
Exam Tips: Answering Questions on Network Diagrams
• Know the terminology: Be familiar with terms like critical path, float, slack, predecessor, successor, and the four dependency types
• Understand PDM vs ADM: Remember that PDM (Activity-on-Node) is more commonly used in modern project management and on the exam
• Practice calculations: Be prepared to calculate the critical path by identifying the longest path through the network
• Remember dependency types: Finish-to-Start is the default and most common dependency - if a question does not specify, assume FS
• Float calculation: Float = Late Start minus Early Start, or Late Finish minus Early Finish
• Critical path characteristics: Tasks on the critical path have zero float; delaying these tasks delays the entire project
• Look for keywords: Questions mentioning sequences, dependencies, or logical relationships are likely about network diagrams
• Differentiate from other charts: Network diagrams show task relationships and sequences; Gantt charts show schedules against time; RACI charts show responsibilities
• Forward and backward pass: Understand that forward pass calculates early dates while backward pass calculates late dates
• Multiple critical paths: A project can have more than one critical path, which increases project risk