How to Identify and Plot Your Project’s Critical Path

6 Steps for Project Success

In our last article, we discussed the crucial nature of the critical path in project management. In this article, we look at a six-step process to identify and plot your project’s critical path.

Step 1: Identify Project Tasks

The first step to plot a critical path is to identify the tasks or activities needed to complete the project. For example, in a building project tasks may include excavation, pouring concrete, building a wall, installing windows and doors, etc.

Each task may be undertaken by different people or contractors. The task itself or the fact that it is undertaken by a different party may be the determinant that the task is separate from others.

When creating the list of tasks, it is essential that dependencies are identified – it is these dependencies that help to identify the critical path. For example, pouring concrete is dependent upon excavation being completed; building walls is dependent upon the footing having been poured and set; installing windows and doors cannot be undertaken until the walls have been built, etc.

Step 2: Identify Duration and Cost

Having identified all the dependent tasks and placed them in order, the project manager must now assign a duration to each. This requires the project manager to consider availability of resources, too. Project resources and time requirements may include:

  • Labour – availability and time that the labour is required.
  • Equipment and materials – if materials are needed, they must be ordered and delivered. Equipment may need to be hired.

Project managers must have a clear understanding of the project’s specifications to estimate labour, equipment and supplies. Experienced project managers will ensure that they have all the details they need before estimating duration and costs – having gained suitable experience by learning lessons in PRINCE2 project management, for example.

Project resources are finalised at a later stage of this process – during resource levelling.

When all resources have been identified, the project manager can estimate duration of each task and make an initial estimate of project cost.

Step 3: Create a Project Diagram

In this third step, the project manager will create a visual depiction of the project, showing the relationship between each task. This ensures that relationships between tasks have been correctly identified. Specific project management software or other formats like Excel may be used to do this.

This diagram identifies the critical path – the longest route through dependent tasks. The project manager will also identify potential early and late finishes and early and late starts. This enables the project manager to identify the likely end date of the project.

Step 4: Compose a Gantt Chart

A Gantt chart enables the project manager to visually depict the project with start and end dates for each task within the project. Resources are included below each task, which enable the project manager to time the availability of all required resources.

Step 5: Resource Levelling

All resources are limited. It’s a fact of life. Resource levelling enables the project manager to maximise the value of resource use. For example, it is better to have a contractor working for eight hours each day for three days rather than 12 hours the first day, none on day two, and four of day three. This is where you might float resources along the project timeline with reference to early/late finishes and early/late starts.

The idea of this step is to flatten peaks and troughs in resource usage, in order to use resources most effectively and solidify the project’s completion date. At this step, the project manager may:

  • Maintain the task duration and move it forward or back along its ‘float’ (the difference between early start and late finish)
  • Increase the duration of the task within the float to smooth resource use
  • Extend the end date of the task – which will mean extending the project’s completion date

Step 6: Compress the Schedule

Though the project schedule may be workable, the project manager may need to compress or lengthen task durations to fit in with resource availability. For example, a key contractor may have annual leave scheduled.

The project manager might ‘crash’ a task (for example, by increasing hours immediately prior to the contractor’s holiday) or fast-track it by performing the task in parallel to another that is usually undertaken in sequence. The risk here is that the task is completed with errors and reworking may be needed.

The project manager must also take other factors into consideration. These include a change of project scope, a reduction in project quality, the potential to outsource tasks, and the potential for external factors to influence the timetable of tasks.

In Summary

In summary, it is crucial that a project manager identifies a project’s critical path. It enables the project manager to provide an accurate estimation of the timeline and resources needed, and provides a reference point to help monitor and measure progress and success.

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