![\"Project](\"https:\/\/plaky.com\/learn\/wp-content\/uploads\/2023\/12\/Project-network-diagram-cover-1.png\")
<\/figure>\n<\/div>\n\n\n- \n
- A project network diagram is a graphical representation of project activities, their flow, and their interconnections.<\/li>\n\n\n\n
- The 2 main types of project network diagrams are the activity-on-arrow (AOA) and the activity-on-node (AON).<\/li>\n\n\n\n
- The PDM diagram is more common nowadays and comprises a series of nodes, which represent activities, and arrows, which indicate the dependencies between those activities.<\/li>\n\n\n\n
- To make an accurate project network diagram, it\u2019s necessary to properly define the project activities, estimate their duration, and establish their dependencies.<\/li>\n<\/ul>\n\n\n\n
What is a network diagram in project management?<\/h2>\n\n\n\n
A project network diagram is a visual tool made of boxes and arrows that maps out the sequence of <\/strong>project activities<\/strong><\/a> and their dependencies.<\/strong><\/p>\n\n\n\n
Project network diagrams are used in project management<\/a> to track the project\u2019s progress and the entire workflow visually.<\/p>\n\n\n\n
A project schedule is often shown in the form of a graph, such as a Gantt chart<\/a>, a milestone chart, or a project schedule network diagram.<\/p>\n\n\n
\n![\"Example](\"https:\/\/plaky.com\/learn\/wp-content\/uploads\/2025\/03\/Example-of-a-project-network-diagram.png\")
Example of a project network diagram<\/figcaption><\/figure>\n<\/div>\n\n\n A project schedule network diagram is a graphical representation of project schedule activities and their interconnections.<\/strong><\/p>\n\n\n\n
Project activities share logical relationships or dependencies that managers use to sequence and schedule them.<\/p>\n\n\n\n
A project network diagram depicts those elements, acting as a visual project roadmap<\/a> that guides the project manager through the project\u2019s life cycle.<\/p>\n\n\n\n
There is no significant difference between the project network diagram and the project schedule network diagram. The latter only focuses more on sequencing activities and placing them on a timeline.<\/p>\n\n\n\n
Today, these diagrams are made in project management software, but they can also be drawn manually. Either way, they should show project work chronologically, from left to right.<\/p>\n\n\n\n
\n\ud83d\udca1 Plaky Pro Tip<\/strong><\/p>\n\n\n\n
Sequencing activities is one of the processes of project time management. To learn more about project time management and its processes, check out the guide below:<\/p>\n\n\n\n
- \n
- What Is Project Time Management?<\/a><\/li>\n<\/ul>\n<\/div><\/div>\n\n\n\n
\n
\n\nFree project management software<\/h2>\n
Forget about using multiple apps and organize all your work in one place: Plaky.<\/p>\n\n
\n Sign up<\/a>\n\n Learn more<\/a>\n <\/div>\n <\/div>\n\n\n\n \n ![\"Illustration\"](\"https:\/\/plaky.com\/learn\/wp-content\/themes\/cake-learn\/src\/images\/plaky\/banners\/default.png\")
\n <\/picture>\n <\/div>\n<\/div>\n <\/p>\n\n\n\nProject network diagram vs. work breakdown structure (WBS)<\/h3>\n\n\n\n
The main difference between a <\/strong>work breakdown structure<\/strong><\/a> (WBS) and a project network diagram is that a WBS doesn\u2019t list project tasks chronologically.<\/strong><\/p>\n\n\n\n
A WBS is a hierarchical breakdown of the project that shows 100% of the project work divided into manageable components.<\/p>\n\n\n\n
In contrast, a project network diagram has a sequential structure and shows project activities in the order they should be completed.<\/p>\n\n\n\n
These 2 project management tools also differ in form. While a WBS often takes the form of a tree diagram, a project network diagram flows from left to right.<\/p>\n\n\n
\n![\"Work](\"https:\/\/plaky.com\/learn\/wp-content\/uploads\/2025\/03\/Work-breakdown-structure-hierarchy.png\")
Work breakdown structure hierarchy<\/figcaption><\/figure>\n<\/div>\n\n\n Types of project network diagrams<\/h2>\n\n\n\n
There are 2 main types of project network diagrams:<\/p>\n\n\n\n
- \n
- Arrow diagram method (ADM<\/strong>) or activity-on-arrow (AOA) diagram, and<\/li>\n\n\n\n
- Precedence diagram method (PDM)<\/strong> or activity-on-node (AON) diagram.<\/li>\n<\/ul>\n\n\n\n
Both types are arrow diagrams, as they include arrows as key elements.<\/p>\n\n\n\n
The main difference between these 2 diagrams is how they represent project milestones<\/a>, activities, and their interconnections.<\/p>\n\n\n\n
Let\u2019s go through both in more detail.<\/p>\n\n\n\n
Arrow diagram method (ADM)<\/h3>\n\n\n
\n![\"The](\"https:\/\/plaky.com\/learn\/wp-content\/uploads\/2025\/03\/The-activity-on-arrow-diagram-in-project-management.png\")
The activity-on-arrow diagram in project management<\/figcaption><\/figure>\n<\/div>\n\n\n The arrow diagram method (ADM) uses arrows to represent the project activities and nodes to depict major milestones or events.<\/strong> It\u2019s also known as the activity-on-arrow diagram.<\/p>\n\n\n\n
Traditionally, the nodes are drawn as circles. The first circle represents the start event and is also called the i-node. The other circle represents the finish event and is also called the j-node.<\/p>\n\n\n\n
Between the nodes are the arrows, whose tails represent the start, while their heads mark the end of an activity.<\/p>\n\n\n\n
The arrow itself shows the logical relationship between the activities, and the length of the arrow indicates an activity\u2019s duration.<\/p>\n\n\n\n
The ADM diagram only shows 1 type of activity relationship \u2014 finish-to-start (FS)<\/strong>. Due to this, it might be necessary to include dummy activities as well \u2014 broken arrows that signify indirect relationships between tasks.<\/p>\n\n\n\n
These dummy activities don\u2019t take part in the sequence and have no duration. Instead, they indicate benchmarks that should be checked off before moving on to a certain activity.<\/p>\n\n\n\n
A great example of the use of the arrow diagram method is PERT (Program Evaluation and Review Technique).<\/p>\n\n\n\n
Precedence diagram method (PDM)<\/h3>\n\n\n
\n![\"The](\"https:\/\/plaky.com\/learn\/wp-content\/uploads\/2025\/03\/The-activity-on-node-diagram-in-project-management.png\")
The activity-on-node diagram in project management<\/figcaption><\/figure>\n<\/div>\n\n\n The precedence diagram method (PDM) uses nodes to represent project activities and arrows to reflect the dependencies between tasks. <\/strong>The PDM is also called the activity-on-node diagram.<\/p>\n\n\n\n
The activity nodes are shown as boxes and linked with arrows. The arrows indicate the 4 types of task dependencies<\/a>:<\/p>\n\n\n\n
- \n
- Finish-to-start (FS)<\/strong> \u2014 The successor activity can begin only when the predecessor activity has been completed.<\/li>\n\n\n\n
- Finish-to-finish (FF)<\/strong> \u2014 The successor activity can\u2019t be finished until the predecessor activity has been completed. <\/li>\n\n\n\n
- Start-to-start (SS)<\/strong> \u2014 The successor activity can\u2019t begin until the predecessor activity has started.<\/li>\n\n\n\n
- Start-to-finish (SF)<\/strong> \u2014 The successor activity can\u2019t be finished until the predecessor activity has started.<\/li>\n<\/ul>\n\n\n\n
Finish-to-start is the most common type of relationship between predecessor and successor activities, while start-to-finish is the rarest.<\/p>\n\n\n\n
The PDM diagram can also capture lead and lag times.<\/p>\n\n\n\n
Lead time is the overlap between 2 activities and is associated with the finish-to-start dependency.<\/strong> It refers to the amount of time a successor activity can begin in advance.<\/p>\n\n\n\n
For instance, if Activity A lasts 5 days, and Activity B has a lead time of 1 day, Activity B can start 1 day before Activity A is completed.<\/p>\n\n\n\n
Lag time is the delay between 2 activities and can be applied to tasks regardless of the dependency. <\/strong>It refers to the amount of time a successor activity can be delayed.<\/p>\n\n\n\n
For example, if Activity C lasts 6 days, and Activity D has a lag time of 2 days, Activity D can only start 2 days after Activity C is completed.<\/p>\n\n\n\n
In a PDM diagram, the lead and lag times can be marked on the arrows, denoted with \u2013 and + symbols.<\/p>\n\n\n\n
How to create a project network diagram (+ example)<\/h2>\n\n\n\n
Creating a project network diagram is simple, especially when you know which steps to take. We\u2019ll use an example to go through all the steps so that you can apply them more easily to your project.<\/p>\n\n\n\n
#1 Identify and define project activities<\/h3>\n\n\n\n
The first step is to properly define project activities<\/strong> as they are the main components of the network diagram.<\/p>\n\n\n\n
For example, let\u2019s say that our project objective is to open a beauty salon. Let\u2019s focus on the task of human resources.<\/p>\n\n\n\n
When broken down, this task includes 2 subtasks:<\/p>\n\n\n\n
- \n
- Recruitment and<\/li>\n\n\n\n
- Training.<\/li>\n<\/ul>\n\n\n\n
We\u2019ll focus on the recruitment subtask, which consists of 4 work packages:<\/p>\n\n\n\n
- \n
- Hire a receptionist,<\/li>\n\n\n\n
- Hire a hairdresser,<\/li>\n\n\n\n
- Hire a stylist, and<\/li>\n\n\n\n
- Hire a makeup artist.<\/li>\n<\/ul>\n\n\n\n
The activity list should contain activity attributes \u2014 descriptive components that further define each activity in your project.<\/p>\n\n\n\n
These attributes provide key information about the activities, such as:<\/p>\n\n\n\n
- \n
- Who\u2019s responsible for task ownership<\/a>,<\/li>\n\n\n\n
- What kinds of project resources<\/a> they require,<\/li>\n\n\n\n
- Each activity\u2019s level of effort, and<\/li>\n\n\n\n
- Predecessor and successor activities.<\/li>\n<\/ul>\n\n\n\n
Since this list defines the activity relationships (dependencies), it will also help us in the next steps of making an accurate diagram.<\/p>\n\n\n\n
\n\ud83d\udca1 Plaky Pro Tip<\/strong><\/p>\n\n\n\n
If you want to learn more about the recruitment process in HR and how to maximize its potential, check out the guide below:<\/p>\n\n\n\n
- \n
- The Recruitment Process in 7 Steps (+ Free Recruitment Template)<\/a><\/li>\n<\/ul>\n<\/div><\/div>\n\n\n\n
\n
\n\nFree task management software<\/h2>\n
Need a tool to organize your team\u2019s activities? Try Plaky today for free!<\/p>\n\n
\n Sign up<\/a>\n\n Download<\/a>\n <\/div>\n <\/div>\n\n\n\n \n ![\"Illustration\"](\"https:\/\/plaky.com\/learn\/wp-content\/themes\/cake-learn\/src\/images\/plaky\/banners\/features.png\")
\n <\/picture>\n <\/div>\n<\/div>\n <\/p>\n\n\n\n#2 Make time estimates<\/h3>\n\n\n\n
Once you have your activity list, it\u2019s time to estimate how long each activity will take.<\/p>\n\n\n\n
According to Jan Schiller<\/a>, Partner and Chief Project Officer at Berkshire Consulting LLC, making accurate estimates requires a bit more than just figuring out the length of each activity:<\/p>\n\n\n\n
\n\n![\"Jan](\"https:\/\/plaky.com\/learn\/wp-content\/uploads\/2023\/10\/Jan-Schiller.jpeg\")
<\/figure>\n<\/div>\n\n\n\n\n\u201cThe best estimates take both effort and duration into consideration and reflect the allocations of resource(s) performing the tasks. Create the estimate yourself if the resource(s) performing the task are not yet available. Validate your estimate with those resources when they become available.\u201d<\/em><\/p>\n<\/div>\n<\/div>\n\n\n\n
<\/div>\n\n\n\nGenerally speaking, you should be able to back up your estimates with knowledge or experience. However, estimates can also be based on project assumptions<\/a>. <\/p>\n\n\n\n
Some of the most commonly used estimation techniques to rely on for this step include:<\/p>\n\n\n\n
- \n
- Analogous estimating (apportionment method),<\/li>\n\n\n\n
- Parametric estimating,<\/li>\n\n\n\n
- Expert judgment,<\/li>\n\n\n\n
- Group decision making,<\/li>\n\n\n\n
- Heuristic estimating (rule of thumb),<\/li>\n\n\n\n
- Reserve analysis,<\/li>\n\n\n\n
- Three-point estimation, and<\/li>\n\n\n\n
- Bottom-up estimating. <\/li>\n<\/ul>\n\n\n\n
For our example, we\u2019ll use the following duration estimates:<\/p>\n\n\n\n
- \n
- 1 day \u2014 activities A, B, C, D, G, I, J, K, L, M, and N,<\/li>\n\n\n\n
- 2 days \u2014 activity F, <\/li>\n\n\n\n
- 3 days \u2014 activity E, and<\/li>\n\n\n\n
- 4 days \u2014 activity H.<\/li>\n<\/ul>\n\n\n\n\n
\ud83d\udca1 Plaky Pro Tip<\/strong><\/p>\n\n\n\n
Some of the estimation methods used to determine the duration of project activities are also used for project management budgeting. Learn more about them here:<\/p>\n\n\n\n
- \n
- Best Project Management Budgeting Methods to Try<\/a><\/li>\n<\/ul>\n<\/div><\/div>\n\n\n\n
#3 Map out the activity sequence<\/h3>\n\n\n\n
Now that we have an activity list and know each activity\u2019s duration, we can focus on activity sequencing.<\/p>\n\n\n\n
In our example, here\u2019s how the activities are connected:<\/p>\n\n\n
\n![\"Sequenced](\"https:\/\/plaky.com\/learn\/wp-content\/uploads\/2025\/03\/Sequenced-project-activities.png\")
Sequenced project activities<\/figcaption><\/figure>\n<\/div>\n\n\n According to Jan Schiller, the project\u2019s activity sequence should be well thought out:<\/p>\n\n\n\n
\n\n<\/figure>\n<\/div>\n\n\n\n\n\u201cSequence the tasks to logically reflect reality. What tasks must be completed before others can begin? What tasks must wait for another task to complete? What tasks must start at the same time, or finish at the same time? When a resource is fully allocated to the tasks, reflect the fact that a resource can only work on one thing at a time by sequencing accordingly.\u201d<\/em><\/em><\/p>\n<\/div>\n<\/div>\n\n\n\n
#4 Draw the network diagram<\/h3>\n\n\n\n
Once you\u2019ve reached step 4, you can use all the collected information to create the type of diagram that suits your needs.<\/p>\n\n\n\n
Whether you use project management software<\/a> or draw it by hand, remember the following:<\/p>\n\n\n\n
- \n
- Your diagram should have only 1 start and 1 end point<\/strong>.<\/li>\n\n\n\n
- The symbols you use should be universally comprehensible<\/strong> and consistent.<\/li>\n\n\n\n
- If you use some other symbols, make sure to define them properly in a diagram legend<\/strong>.<\/li>\n\n\n\n
- Use straight arrows<\/strong> and try not to overlap them.<\/li>\n\n\n\n
- Don\u2019t overpopulate your ADM diagrams with dummy activities<\/strong>.<\/li>\n\n\n\n
- Keep it simple \u2014 the diagram should be easy to understand at a glance<\/strong>.<\/li>\n<\/ul>\n\n\n\n
Based on the example above, here\u2019s what the ADM diagram looks like:<\/p>\n\n\n
\n![\"Activity-on-arrow](\"https:\/\/plaky.com\/learn\/wp-content\/uploads\/2025\/03\/AOA-diagram-example.png\")
Activity-on-arrow diagram example<\/figcaption><\/figure>\n<\/div>\n\n\n This type of diagram is not used so much these days, so you\u2019re more likely to make a PDM diagram for your projects, especially if you want to find the project\u2019s critical path<\/a>.<\/p>\n\n\n\n
Here\u2019s what the PDM diagram for this example looks like:<\/p>\n\n\n
\n![\"Activity-on-node](\"https:\/\/plaky.com\/learn\/wp-content\/uploads\/2025\/03\/AON-diagram-example.png\")
Activity-on-node diagram example<\/figcaption><\/figure>\n<\/div>\n\n\n You can see the nodes in this diagram are split into 7 panels. Since PDM diagrams are used in the critical path method, you can fill in the blanks with other activity values, such as:<\/p>\n\n\n\n
- \n
- Early start and finish times,<\/li>\n\n\n\n
- Late start and finish times, and<\/li>\n\n\n\n
- Total float<\/a>. <\/li>\n<\/ul>\n\n\n\n
Since some activities have multiple predecessors or successors, the diagram must illustrate that via path divergence<\/strong> or path convergence<\/strong>.<\/p>\n\n\n\n
Path divergence happens when an activity has more than one successor, while path convergence is when an activity has more than one predecessor.<\/p>\n\n\n\n
\n\ud83d\udca1 Plaky Pro Tip<\/strong><\/p>\n\n\n\n
Want to learn about the origin of critical chain project management, its pros and cons, and how it differs from CPM? Check out the following guide:<\/p>\n\n\n\n
- \n
- What Is Critical Chain Project Management (CCPM)?<\/a><\/li>\n<\/ul>\n<\/div><\/div>\n\n\n\n
#5 Review and update the diagram with current data<\/h3>\n\n\n\n
Once the diagram is set up, make sure it\u2019s easy to understand and keep updating it regularly.<\/p>\n\n\n\n
Apart from using a project management tool to create the diagram, Jan Schiller recommends adding a summary view as well:<\/p>\n\n\n\n
\n\n<\/figure>\n<\/div>\n\n\n\n\n\u201cSupport project communication with a summary view of the project network diagram. This will help project teams and executives alike to understand the way the work must flow to achieve the project\u2019s result.\u201d<\/em><\/em><\/em><\/p>\n<\/div>\n<\/div>\n\n\n\n
However, if the diagram is already too big and seems disorganized, she believes it might be a good idea to switch tools:<\/p>\n\n\n\n
\n\n<\/figure>\n<\/div>\n\n\n\n\n\u201cSwitch to a Gantt chart visual when the project network diagram becomes too large and unwieldy. A project network diagram does not replace the need for a Gantt chart (which visually places the tasks in the context of a timeline).\u201d<\/em><\/em><\/em><\/em><\/p>\n<\/div>\n<\/div>\n\n\n\n
Jan also emphasizes the importance of relying on accurate planning data when making the diagram:<\/p>\n\n\n\n
\n\n<\/figure>\n<\/div>\n\n\n\n\n\u201cThe project network diagram is a critical prerequisite to determining a project\u2019s schedule (and therefore, project costs). [But] the project network diagram is only as good as the planning data the diagram is visually representing: a complete list of tasks that are accurately estimated and sequenced properly.\u201d<\/em><\/em><\/em><\/em><\/em><\/p>\n<\/div>\n<\/div>\n\n\n\n
To ensure the diagram\u2019s accuracy and general usefulness, Jan\u2019s advice is simple but precise:<\/p>\n\n\n\n
\n\n<\/figure>\n<\/div>\n\n\n\n\n\u201cDevelop the initial project network diagram thoughtfully. Keep this data current throughout the life of your project.\u201d<\/em><\/em><\/em><\/em><\/em><\/em><\/p>\n<\/div>\n<\/div>\n\n\n\n
Benefits of using a project network diagram<\/h2>\n\n\n\n
Some of the major benefits of using a project network diagram are that it:<\/p>\n\n\n\n
- \n
- Defines and streamlines the project workflow<\/a>, identifying all the activities that should be done and the sequence they should follow,<\/li>\n\n\n\n
- Visually communicates key project data, such as critical activities and dependencies, helping the project manager<\/a> better understand the workflow and pinpoint errors and potential bottlenecks, <\/li>\n\n\n\n
- Helps identify and resolve project issues,<\/li>\n\n\n\n
- Enables easier project planning and simplifies scheduling,<\/li>\n\n\n\n
- Allows for more methodical resource allocation<\/a>,<\/li>\n\n\n\n
- Improves the team\u2019s understanding of the project scope<\/a> and everything they must do to meet the project goals<\/a>,<\/li>\n\n\n\n
- Boosts the project team<\/a>\u2019s efficiency, productivity, and performance, and<\/li>\n\n\n\n
- Gives the team a deeper insight into their responsibilities and level of contribution. <\/li>\n<\/ul>\n\n\n\n
When asked about the benefits of project network diagrams, Jan Schiller highlighted conflict and issue identification:<\/p>\n\n\n\n
\n\n<\/figure>\n<\/div>\n\n\n\n\n\u201cAny scheduling conflicts or issues are identified proactively when there is adequate project runway to address and resolve those issues to ensure a predictable schedule.\u201d<\/em><\/em><\/em><\/em><\/em><\/em><\/em><\/p>\n<\/div>\n<\/div>\n\n\n\n
She also reflected on the use of visual aids to support better communication and manage project stakeholder<\/a> expectations:<\/p>\n\n\n\n
\n\n<\/figure>\n<\/div>\n\n\n\n\n\u201cBecause visual representations of project information are easier to understand than a view of all of the source data, project communications, and project expectation management become easier.\u201d<\/em><\/em><\/em><\/em><\/em><\/em><\/em><\/em><\/p>\n<\/div>\n<\/div>\n\n\n\n
\n\ud83d\udca1 Plaky Pro Tip<\/strong><\/p>\n\n\n\n
What role does communication play in project management and how can you improve it to support your project\u2019s success? Read all about it and get useful tips in the guide below:<\/p>\n\n\n\n
- Visually communicates key project data, such as critical activities and dependencies, helping the project manager<\/a> better understand the workflow and pinpoint errors and potential bottlenecks, <\/li>\n\n\n\n
- Defines and streamlines the project workflow<\/a>, identifying all the activities that should be done and the sequence they should follow,<\/li>\n\n\n\n
- What Is Critical Chain Project Management (CCPM)?<\/a><\/li>\n<\/ul>\n<\/div><\/div>\n\n\n\n
- The symbols you use should be universally comprehensible<\/strong> and consistent.<\/li>\n\n\n\n
- Your diagram should have only 1 start and 1 end point<\/strong>.<\/li>\n\n\n\n
- Best Project Management Budgeting Methods to Try<\/a><\/li>\n<\/ul>\n<\/div><\/div>\n\n\n\n
- What kinds of project resources<\/a> they require,<\/li>\n\n\n\n
- Who\u2019s responsible for task ownership<\/a>,<\/li>\n\n\n\n
- Finish-to-finish (FF)<\/strong> \u2014 The successor activity can\u2019t be finished until the predecessor activity has been completed. <\/li>\n\n\n\n
- Precedence diagram method (PDM)<\/strong> or activity-on-node (AON) diagram.<\/li>\n<\/ul>\n\n\n\n
- Arrow diagram method (ADM<\/strong>) or activity-on-arrow (AOA) diagram, and<\/li>\n\n\n\n
- What Is Project Time Management?<\/a><\/li>\n<\/ul>\n<\/div><\/div>\n\n\n\n
![\"Illustration\"](\"https:\/\/plaky.com\/learn\/wp-content\/themes\/cake-learn\/src\/images\/plaky\/banners\/default@2x.png)
\n <\/picture>\n <\/div>\n<\/div>\n <\/p>\n\n\n\n![\"Illustration\"](\"https:\/\/plaky.com\/learn\/wp-content\/themes\/cake-learn\/src\/images\/plaky\/banners\/features@2x.png)
\n <\/picture>\n <\/div>\n<\/div>\n <\/p>\n\n\n\n