Project Management

What Are Network Diagrams in Project Management, and Why Are They Effective?

Written byContributing Writer
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Updated onMay 29, 2024

As a project manager, you’re expected to ensure every project is completed most efficiently. You must use every resource to plan, monitor, and troubleshoot problems. A network diagram is a method that enables you to do that.

Known for its pictorial efficiency, a network diagram has been the choice of project managers for several years to visualize the project. Hence, every aspiring project manager must know a network diagram and how to use it.

Keep reading as we cover the key concepts related to network diagrams, their types and advantages, and more. We will also recommend an industry-relevant project management program for those who want to gain more in-depth knowledge of network diagrams and other skills to build a career in this field.

Understanding Network Diagrams

A network diagram is a graph that presents a project’s various stages and elements. It is created from a series of arrows and boxes interconnected to denote the interrelationship between the phases and tasks of the project. Arrows indicate the relationship between the operations, and nodes or boxes describe the activities. Additionally, all the activities in the network diagram must have a finish and end.

While multiple ways to plot a network diagram exist, two are preferred for several projects worldwide. These activities are the arrow diagramming method (ADM) and the precedence diagramming method (PDM). The popularity of PDM has grown more than that of ADM worldwide.

Also Read: What is Project Scope Management?

Understanding Different Types of Network Diagrams

Drafting an accurate and useful network diagram requires assessing the nature of activities and prioritizing them as successors and predecessors. Further, you must develop a dependencies chart and a logical relationship between the various activities. You can use GERT to evaluate the dependencies. We will discuss GERT briefly in the subsequent section.

This section will discuss the two primary types of project network diagrams: the precedence diagram method (PDM) and the arrow diagram method (ADM).

Precedence Diagram Method (PDM)

The precedent diagram Method (PDM) is considered to be more effective than the arrow diagram method (ADM). PDM is also called node network or activity on node. In this method, the arrows indicate the relationships between the activities, and the nodes, or boxes, denote the activities. The arrows represent four types of logical relationships.

Finish to Start (FS): Finish to Start is a relationship that indicates that the successor’s activity begins only after the predecessor’s activity ends. Unless your project implements a schedule compression technique, you must wait for the predecessor’s activity to finish. However, this process may result in reduced product quality.
Start to Start (SS): In this type of relationship, you do not have to wait for the predecessor’s activity to end. The successor’s activity can begin after the predecessor’s activity begins. Thus, more than two activities can run simultaneously with a partial dependency.
Finish to Finish (FF): This type of relationship limits the activities’ completion. So, irrespective of the start of the activities, the predecessor’s activity has to finish before the successor’s activity ends. However, this type of diagram is not as popular in the current project management scenario.
Start to Finish (SF): In this type of relationship, the predecessor’s activity begins after the successor’s activity finishes. Due to its seemingly counter-intuitive nature, this type of diagram has almost become obsolete.

Further, PDM has four dependencies: mandatory, discretionary, external, and internal. Each dependency has distinct features that can be applied whenever suitable for a project.

PDM can be used as a project update tool to update the stakeholders regularly. It is useful for identifying missed opportunities and tasks. The team members who use PDM know their responsibilities and the schedule for their activities.

Arrow Diagram Method (ADM)

Although project managers nowadays do not prefer the arrow diagram method, they must know what it is and when it can or cannot be used. In ADM, the arrows indicate the project’s associated activities. It is also referred to as the activity network diagram.

It has certain key characteristics, such as those described subsequently.

The length of the arrows measures and indicates the duration of an activity. The project managers can mention the lag or lead times in the space adjacent to the arrows.
The head of the arrow indicates the finish, while the tail indicates the beginning.
The arrows connect a pair of boxes called ‘nodes.’ The nodes denote the start and end of the activities. The starting node is called the ‘i-node,’ while the ending node is the ‘j-node.’
This graph can present only a Finish-to-Start dependency. It does not provide for other dependencies, such as Start-to-Start or Start-to-Finish.
It may consist of arrows without any boxes, denoting dummy activities.

ADM is primarily used when the project is complex and requires intricate scheduling. It is also useful when the project managers know the exact steps of the project, their duration, and chronology. It may be implemented when the project is critical, and any delay or interruption has serious consequences.

If completing a project before the schedule may benefit the organization greatly, ADM is the perfect candidate for such cases.

Project Schedule Network Diagram in Project Management

A project schedule network diagram denotes the chronology of activities and tasks in the project. It visually represents the logical and sequential relationship between the project’s activities. While a project network diagram offers a graph of activities based on their dependencies, a project schedule network diagram focuses more on workflow, timelines, and schedules.

It is used as a project map to track the progress of the various stages. You can efficiently chart out the project’s scope based on its duration and the magnitude of the tasks.

Also Read: What is Change Management in Project Management?

Exploring GERT

GERT stands for Graphical Evaluation and Review Technique. This kind of network chart is not used as frequently nowadays. Even so, the network diagrams are significantly rooted in this concept.

GERT uses arrows to denote activities and nodes to indicate the connection between them. The nodes establish the relationship between the activities with respect to parameters such as conditions, type, features, etc. Every activity is characterized by its probability of appearance and duration.

GERT uses logical operators to assign nodes to the incoming activities. These operators are XOR alternative, OR alternative, or AND alternative.

The XOR alternative indicates the possibility of only one path. The OR alternative denotes one or more paths. The AND alternative demonstrates that all the paths are necessary. It indicates the scenario where each incoming activity must occur before the beginning of any outgoing activities.

Further, two relations are prominently used in GERT to describe the outgoing node activities: deterministic and probabilistic. In a deterministic relation, a probability value of 1 is assigned to each outcoming activity, describing that the activity will be completed. In a probabilistic relation, the outgoing activity has a probability of appearance, but it may not always be 1.

A distinct feature of GERT is ‘loops,’ which denote the repetition of the activity in case of undesirable outcomes. The probability of repetition is often calculated to assess the efficiency of the corrective actions.

Additionally, it may contain multiple sink nodes (multiple outcomes), probabilistic branching (stochastic models), multiple node realization (repeat events), and network looping (feedback loops). Hence, it is primarily used for modeling and analysis of real-world examples.

What Are the Advantages of Network Diagrams?

Using a network diagram has distinct advantages that every aspiring project manager must know. Here are some of them.

A network diagram builds collaboration between stakeholders such as the project manager, team members, and management. They can efficiently visualize the entire project and provide input.
It helps the project manager gain insights and build a comprehensive graph.
It is exceedingly helpful and a quick reference for new team members who do not have to go through the entire project background.
The project managers can identify the mandatory dependencies and adjust the network diagram accordingly.
It provides an idea about the total project duration based on each activity’s resources and working hours.
Project managers can plan better schedules and track the project’s progress.
It helps identify bottlenecks and inefficient processes.
It improves the comprehension of the various stages of the project.

Also Read: How to Use Microsoft Access: A Comprehensive Guide

Want to Deepen Your Learning About Network Diagrams and Other Project Management Concepts?

Every project manager must be knowledgeable about their project, what it entails, and how it should progress. They can successfully achieve the project goals only when they plan the project details. Hence, they must know key concepts such as network diagrams that can help them map the project and help their team members understand the scope and schedule of the project.

A great first step in accomplishing this is to join an industry-recognized project management bootcamp. The program is specially curated to match industry requirements and will equip you with a solid understanding of PMP concepts, Agile, and Scrum methodology. In addition to learning project risk management, design thinking, and implementing a project management office, you’ll also benefit from hands-on training and networking opportunities.