Things to Know about Schedule Network Diagram

A project schedule network diagram is a proven technique for determining and documenting the sequence of activities, taking interdependencies into account, when scheduling projects.

In Project Management, what is a Network Diagram?

Network diagrams should be familiar to you whether you are a project manager or a team member. Project network diagrams are important because they help teams look after the activities they need to complete over the course of a project, as well as providing crucial contexts such as task duration and dependency.

What Do You Understand by Project Network?

Project networks display the activities within the project, their duration, and their interdependencies. In a project schedule network diagram, activities are arranged in an order that addresses their logical relationships.

The goal of a project schedule network diagram is to illustrate the sequential and logical relationship among tasks, and it relies on expressing a clear chronology of events.

Network diagrams for projects are typically depicted as charts with boxes and arrows. Through this tool, you can map out the project's schedule and sequences of work and monitor its progress through every stage. In addition to illustrating the scope of the project, a network diagram is even useful for illustrating the large tasks that must be completed during the project's duration.

Project Management Network Diagram Benefits

By using a network diagram, a manager can track the progress of each element in a project, as well as share the status of the project with other people. Some benefits involve −

  • Stakeholders can see progress visually

  • Creating a workflow for a project

  • Monitoring dependencies and bottlenecks

In addition to improving comprehension and retention, research shows that displaying data visually can also reduce stress among team members while boosting their performance.

Diagram Types: Arrow Diagrams and Precedence Diagrams

An arrow diagramming method is one type of network diagram in project management. The precedence diagramming method is another type.

Arrow Diagram Method (ADM)

As a result of its limitations, the activity network diagram, also known as an ADM, is not quite widely utilized in project management. Arrows represent the project's activities. ADMs are still important to know so that you can recognize them if they appear in your workplace.

In ADM −

  • An arrow's tail represents the beginning and its head shows the end of the activity.

  • Typically, the arrow length represents the activity's duration.

  • In a sequence of activities, every arrow is connected with two boxes called "nodes." Each node represents the beginning or end of the activity. The first node of a sequence is known as the "i-node," while the last node is known as the "j-node."

  • An ADM chart can only show the "finish to start" relationship between nodes and activities.

The ADM network diagram sometimes requires "dummy activities" or arrows that indicate no direct relationship.

Precedence Diagram Method (PDM)

The use of PDM network diagrams in project management is becoming quite popular today and is considered to be a more effective method than ADMs. The precedence diagramming method creates network diagrams by separating activities into boxes and indicating relationships between them with arrows. All possible relationships can therefore be represented by the arrows −

  • A "Finish to Start" (FS) situation occurs when the task cannot begin until another activity has finished

  • Two activities can start simultaneously when they are called "Start to Start" (SS)

  • “Finish to Finish” (FF) refers to two tasks that need to be completed simultaneously

  • The Start-to-Finish (SF) dependency occurs when one activity cannot be completed until the other can be completed.

Along with the arrows, PDM allows writing lead and lag times. Using the arrow representing the relationship between the connected nodes, you can simply write ten days over the arrow when a particular activity will take place after 10 days.

The Usage of Project Network Diagram

Developing and documenting the sequence of activities is done using a project network diagram. A schedule network analysis or a critical path method is used as inputs for other scheduling techniques in the ‘project schedule management’ knowledge area.

The same diagram can be used to communicate with stakeholders in a project as well as to discuss sequences and dependencies. Occasionally, however, it is a more complex and detailed document that relates the tasks and activities to the overall schedule and duration of the project.

Rather than schedule network documents, many organizations rely on other ways of presenting the schedule (like the Gantt diagrams) and a more aggregated view. Slacks, floats, leads, and lags of activities are also documented using schedule network diagrams. The critical path is identified by identifying the longest chain of activities.

What is the Process for Creating a Schedule Network Diagram?

Scheduling network diagrams require inputs such as the definition of defined activities, their estimated durations, and their logical relationships (also known as dependencies).

You will need the following to draw a schedule network diagram (according to the AON method) −

  • As a starting point, draw a circle,

  • You can add activities to the (future) nodes of your diagram, along with details and additional information,

  • The precedence diagramming method explains how to connect activities by arrows, which represent logical relationships.

  • Each relationship should be described in detail, including the type of dependency (e.g. SS, FS), its necessity or discretion, lead times and lag times, as well as any other information relevant to your scheduling.

  • The diagram should have an endpoint.

In addition to the earliest start and latest finish dates, activities are often referred to as critical, as well as work packages or work breakdown structures. It is also possible to include waiting time, or slack or float, between activities.

When developing a schedule network diagram, activities are drawn as arrows and dependencies are drawn as nodes if you prefer the activities-on-arrows (AOA) method.

Scheduling software is typically used to create these diagrams in projects to support project management. It is the user's responsibility to provide input data, i.e., the list of activities, the logical relationships, and the leads and lags, which are the same. After drawing the diagram, the software determines the most optimal sequence of activities.

It is also possible to create the diagram manually using standard office software such as Visio or PowerPoint if you do not have the right software at hand.


Scheduling network diagrams are useful for visualizing a project's sequence and logical relationships. Following the arrows and taking the types of relationships, leads, and lags into account, you can determine a path's duration and, ultimately, identify the critical path. While project management software is often used to sequence activities, understanding the dependencies between activities and their impact on the project schedule is crucial. In addition to the PMP exam, real-life project schedules are often developed based on this principle.

Updated on: 02-Feb-2023


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