Critical Path Project Management: Definition and Examples

Project managers often use the critical path method to outline and plan for a large or complex project, as well as estimate its completion timeline. Creating a critical path for a project includes a step-by-step list with the assumption that the each task must be done before beginning the next one on the list. In this article we will discuss what the critical path method and how you can apply it in your own work.

What is critical path?

Critical path project management or “CPM” is the sequence of tasks required to complete a specific project on time. Creating a critical path plan involves looking at every step required along the way to reach a certain result. Defining and clearly outlining those steps is necessary to estimate with a reasonable completion timeframe, so project managers work with the team members involved in each step to understand bandwidth and other effects on time to completion. Working with the team allows the project manager to better define the work needed to achieve the project's scope.

A critical path schedule breaks down the work tasks into smaller units, often referred to as work packages. A project manager can assign a task to an individual, giving them complete ownership over that portion of the project. A work package should also have someone assigned to oversee and control of all of its elements including risk, materials needed, cost and time. Many project managers also define a work package as something that takes between eight and 80 hours to complete.

After mapping out the project critical path, the next step is creating a diagram of the results. This responsibility usually falls on the project manager who is responsible for the overall critical path method and result. By putting all the work packages together, the project manager can determine the proper order in which they must be completed along with an estimated timeline of when each step should begin to meet the time goal.

In order to accommodate potential delays or issues that arise within work packages, the diagrammed critical path schedule should include several key measures:

  • Early start: The earliest time in which a work package could begin.
  • Early finish: The earliest time in which a work package could be completed.
  • Late start: The latest time in which a work package could begin and not result in a delay.
  • Late finish: The latest time in which a work package could be completed and not result in a delay.
  • Float/slack time: Potential time for delays on a work package that will not result in an overall timeline delay.

By diagramming the information about the project schedule, the project manager will gain more accurate calculations for the targeted end date. Identifying any potential slack or float time is an important step in the process of creating a critical path diagram.

Benefits of the critical path method

When overseeing a project, a project manager can often feel overwhelmed by all the tasks that must be completed before reaching the end goal. Working with a team also involves outsourcing the work to members of that team, which can cause delays and take aspects of the project out of the PM's hands. Project managers might also be responsible for reporting progress to managers and executives in the company, so the timeline estimates and associated tasks must be accurate.

Critical path method scheduling allows a project manager focus on the larger picture instead of being slowed down by smaller details. By creating a specific schedule and working with those who will be responsible for completing each task along the way, it's easier to determine an accurate timeline and track what needs to be completed for each step. A critical path chart, also called a diagram, puts all team members on the same path toward completion while clearly outlining who is responsible for what task.

Critical path methodology project management also becomes a tool of reference for monitoring progress and reporting on each task as it is completed. The project manager may need to adjust the resources allocated to a certain work package if it is taking longer than expected or potentially causing a delay. In order to be effective, project managers must continue to consult the critical path plan throughout the project to prevent delays and keep the work moving.

Critical path example

The CPM is meant to determine how long each task takes before you can finish a project. The method is flexible, allowing you to adjust tasks and timelines along the way.

The step-by-step aspect of CPM is particularly useful during construction projects because of the physical nature of the work. The task manager over the drywall of a building, for example, cannot complete their work until the framing and steel erection are complete. Every step has a timeline and must be finished before the next task manager can step in and get started.

However, not all industries and projects will benefit from creating steps that must be completed in sequence. Some will require elements of the project to be completed either simultaneously or out of sequence. Creating a diagram as part of the critical path project management methodology allows the PM to create a visual representation of each task that needs to be completed and when it needs to be finished in order to keep the project on time.

When reviewing this project critical path analysis, the PM can decide which tasks can be completed in tandem. Running multiple tasks at the same time is also referred to as fast-tracking, which can reduce the overall time needed to complete the project. In order to fast-track any steps in the CPM style, the project manager must have excellent resource management skills. Since multiple steps or tasks will be happening at the same time, each needs sufficient resources allocated to it to avoid delays. The overall quality of the work may also drop if a task doesn't have enough resources allocated, which can impact the project's outcome.

Going back to the construction critical path method example, certain elements of the project may be worked on at the same time as long as they don't directly overlap or compete. While the steelworkers are erecting the frame, perhaps the plumbing sub-contractor could be mapping out the pipes and installing them beneath the ground. When mapping out the critical path of a project, determining which tasks can be handled simultaneously can trim the final timeline and allow more team members to work at the same time.

The construction industry is one where critical path management is highly utilized and valued. Project managers involved in construction understand the value of driving efficiency through the creation and tracking of reasonable timelines. In order to succeed with the critical path management method on a construction job, the PM must oversee all task managers carefully. A mistake in one task could ultimately impact the outcome of the following tasks, pushing back the project's completion date.

Utilizing critical path analysis

To better understand critical path project management, reviewing some examples of others' analyses can be helpful. A project manager can determine the best format for critical path analysis. Some use spreadsheets, while others create actual diagrams with arrows pointing to the specific tasks along the way. Reviewing examples in several formats can provide additional insights and options for the best method based on the scope and needs of the project.

To define critical path, a project manager can look at the overall timeline for a project and then break that timeline out into specific tasks. Those tasks become the milestones along the path to completion of the project, which can be assigned to other members of the team involved. A project manager is responsible for overseeing the timeline and making sure that each task is on target for completion by the required end date.