This is a guide to project planning covering 4 stages. If you haven't read steps 1, 3 or 4, you can access them here. Stage 1 - Work Breakdown Structures, Stage 3 - estimating effort and scheduling, Stage 4 - resource allocation and levelling. The first step in planning is to breakdown the tasks that are needed to deliver the sum total of the project in a Work Breakdown Structure.

Knowing the tasks that need to be done is essential, but you also need to know in what order they need to be done. Stage 2 of project planning focuses on the order in which the tasks need to happen. To understand that we need to create a Precedence Diagram.

What is a Precedence Diagram?

Before diving into the practical steps of creating a precedence diagram, it's crucial to understand what one is and why it's so essential in project planning. A precedence diagram, also known as a Project Network Diagram or PERT (Program Evaluation and Review Technique) chart, is a visual representation of the sequence in which tasks must be completed to finish a project efficiently. This diagram helps project managers identify the most efficient sequence of events necessary for project completion. It visually outlines tasks, their dependencies, and helps you to identify the critical path of the project, which are the tasks that directly impact the project timeline.

How to create a Precedence Diagram

1. Tape some flipchart paper to the wall or use whiteboard.


2. Put the top deliverable from your work breakdown structure on to the right hand side of the board or paper.


3. Take each of the lowest level post-its from your breakdown structure and arrange them in the order in which they need to happen.


4. Work from the left to the right and draw lines between the tasks to show relationships between them.

Focus on the sequence of the tasks. Be careful not to think about resources or other constraints. Just think about what order the tasks could go in assuming no restrictions. As you go through this exercise you may identify additional tasks - add them to the precedence diagram and to the work breakdown structure. Finally draw arrows between the tasks that link up, and make sure that there aren’t any tasks sitting isolated. You should have a flipchart or whiteboard that looks like this. This is fantastic because this shows you the dependencies between tasks and it enables you to put together a critical path for your project. Don’t worry about calculating the critical path MS Project can do that for you. The point is you can’t calculate an accurate critical path unless you have been through this process. This article explains what I mean by the critical path.

I strongly suggest that you go through this stage in a collaborative fashion with your team because you are not necessarily going to know what all of the dependencies are.

Enter the tasks into your project scheduling software

By now the meeting room will probably be covered in post-its and you need to transfer it all into your scheduling software. You can either stay in the room or take a series photographs. I tend to stay in the room so that I can get everything in to MS Project and be sure that I haven’t missed any dependencies.

Type all of the tasks into your project scheduling software. As far as possible, try to follow the logical sequence on your precedence diagram. The great thing about these diagrams is that they provide you with the information you need to correctly link the tasks in the planning software. Make sure each task is correctly associated with its predecessors. Most scheduling software will enable you to link tasks so that you can accurately reflect the sequence in your diagram. Don't worry about resource availability at this stage.

Task Dependencies

Microsoft Project offers four ways to illustrate task dependencies (link types). The diagram below illustrates each task dependency type.

Finish to Start

Looks like:
The start of a task has an arrow from the finish of another task.

Means that:
The task can't start until the other task has finished.

Start to Start

Looks like:
The start of a task has an arrow from the start of another task.

Means that:
The task can't start until the other task has started.

Finish to Finish

Looks like:
The finish of a task has an arrow from the finish of another task.

Means that:
The task can't finish until the other task has finished.

Start to Finish

Looks like:
The finish of a task has an arrow from the start of another task.

Means that:
The task can't finish until the other task has started.

Check the sequence of tasks

If you are using Microsoft Project you can check that you have the correct sequence in the Gantt chart view. I suggest that you always check the dependencies for your project carefully as mistakes in the logic can prove very costly. Every Project Manager will have experienced that moment of panic when they realise that a task link is missing, and on adding the predecessor they find that the project end date moves to month later than planned.

Can you create a precedence diagram in Microsoft Project without drawing a diagram first?

No, you don't always need to create a precedence diagram using only boxes and lines on paper or a whiteboard; there are several digital tools that can help you create these diagrams efficiently, including Microsoft Project.

Microsoft Project is particularly well-suited for creating precedence diagrams because it has built-in features for managing tasks, dependencies, and timelines. When you enter tasks into Microsoft Project, you can define the relationships between them using different types of links like Finish-to-Start, Start-to-Start, Finish-to-Finish, and Start-to-Finish. Microsoft Project then automatically generates a Gantt chart, which is a type of bar chart that represents a project schedule including dependency relationships between activities.

While a Gantt chart in Microsoft Project visually represents task sequences and durations, it also implicitly contains the precedence relationships you would find in a more traditional network diagram. For more explicit network diagram visualizations, Microsoft Project has a "Network Diagram" view which shows tasks as boxes (or nodes) and dependencies as lines (or arcs). This view resembles the traditional precedence diagram and can be very helpful for understanding task dependencies visually.

To switch to the Network Diagram view in Microsoft Project:

• Open your project in Microsoft Project.
• Go to the 'View' tab in the ribbon.
• Click on 'Network Diagram' in the Task Views group.

This view allows project managers to see the flow of project activities and how each task is connected, making it easier to identify the critical path and any potential bottlenecks in the project. Using Microsoft Project for this purpose not only simplifies the creation and updating of precedence diagrams but also integrates them seamlessly into the broader project management process, ensuring all data remains aligned and up-to-date.

Now we have broken down the work and identified the Task Dependencies it is time to estimate the effort for each task. Stage 3 - Estimate effort