Why Is the Critical Path Method Essential for Project Management?


The Critical Path Method (CPM) is a powerful tool for construction project management.

By identifying the essential tasks required to finish the project on time, CPM can help project managers design a master schedule, proactively identify potential problems, and keep their projects on track.

What is the critical path method?

The critical path method (CPM) is a framework that helps project managers identify and track the sequence of tasks required to achieve specific milestones.

The Critical Path Method (CPM) ‘s basic philosophy is that all project tasks are interdependent and follow a particular order. 

Some tasks are critical and must be done in order. Other activities are flexible and do not directly affect the project’s completion timeline.

By identifying the project’s essential tasks and milestones and completing them in order, project managers increase the likelihood of finishing their projects on time. 

Also, while carefully planning and laying out the critical path, project managers identify potential problems early, giving them time to make corrections.

This crucial information gives project managers the insights they need to identify potential bottlenecks and delays and adjust accordingly.


What are the benefits of the critical path method (CPM)?

There are many benefits to using the Critical Path Method in construction projects. 

First, the CPM gives project managers a framework to identify the project’s most important tasks. Project managers can schedule the appropriate amount of time, attention, and resources to ensure completion by identifying these critical tasks.

Second, CPM can help identify potential problems early on in the project. Early problem identification allows time for corrective action, so issues don’t develop into costly delays and time-consuming rework. 

Finally, CPM provides a clear path for the project manager to follow, making it easier to stay on schedule.

The Critical Path Method (CPM) is a powerful tool. And when intelligently deployed, monitored, and maintained, the CPM helps project managers direct their work team’s efforts, which saves valuable time, money, and effort. 


Are there any limitations to using the critical path?

The critical path method (CPM) is a staple of construction project management but has limits.  For one, the CPM can be complex to set up and manage, especially for large projects. 

Furthermore, if tasks and work packages are not well-defined or the estimated time to complete a task is inaccurate. And as a consequence, the CPM schedule will not be accurate either.

A critical path schedule is only as good as the data that goes into it. That means the CPM will only succeed with accurate and up-to-date information on task durations, available resources, and confirmed subcontractor schedules.

CPM isn’t foolproof and cannot account for the inevitable delays, disruptions, and setbacks that plague construction projects. Even with a perfect CPM schedule, projects can still be delayed or even derailed by unforeseen events.

And finally, the CPM cannot account for the impact of changes such as RFIs, RFPs, design changes, change orders, labor disputes, and instances when tasks take longer than anticipated.

What method do project managers use to set up a CPM schedule?

  1. To create a CPM schedule, begin with a clearly defined project scope and then decompose the project scope into phases.
    1. Preconstruction: 
      1. Site survey, 
      2. layout, 
      3. permits, and 
      4. approvals
    2. Sitework and Utilities: 
      1. Earthmoving, 
      2. site balance, 
      3. underground service utilities,
    3. Footings and Foundations: 
      1. Excavation, 
      2. pilings, 
      3. piers, 
      4. footings, and 
      5. foundation work 
    4. Structural Framing: 
      1. Steel erection, 
      2. exterior and interior framing,
    5. MEP: 
      1. Rough Mechanical, Electrical, and Plumbing installations. 
      2. The MEP phase also includes data cabling and telecommunications
    6. Features, Fixtures, and Finishes: 
      1. Exterior skin, exterior glazing, and interior walls
      2. MEP, data, and telecommunication system finishes
      3. Interior features, fixtures, glazing, and finishes
      4. Site grading, pavement, and landscaping
  2. Next, decompose the project phases into work breakdown structures (WBS) by decomposing every project component within the phases into smaller, manageable tasks. 
  1. Estimate the time required to complete each task.
    1. Accurate task-time estimation is crucial for creating an accurate CPM schedule.
    2. Use an integrated project management information system (PMIS) to pull data from previous projects with similar WBS for comparison. 
  2. Establish task dependencies.
    1. Further define the work breakdown structures by identifying their dependencies
      1. Dependencies define the order of operations for each task within a work package. 
      2. Work packages must progress in a logical sequence to avoid disruption. 
  3. Create a Critical Path Diagram.
    1. With a defined project scope, task dependencies, and estimated time durations for each task, it’s time to create the critical path diagram.
    2. The critical path diagram is a visual representation of the major milestone activities required for the project, laid out in chronological order.
    3. Many milestone activities overlap, so a visual process diagram is an indispensable project management tool.
  4. Identify the critical path: Each major milestone activity has four parameters.
    1. Earliest start time (ES): The earliest start of an activity depends on the earliest finish of that task’s previous dependent activity.
    2. Earliest finish time (EF): Adding the activity duration to the earliest start time determines the earliest time that activity can finish.
    3. Latest finish time (LF): The LF is the latest time an activity can finish without delaying the project
    4. Latest start time (LS): Determine the latest start time by subtracting the activity time from the latest finish time.

What are float and slack in the critical path method?

Float and slack describe the same essential concept in project management. We’ll use float for the sake of this article.

There are two types of float:

  • Free float (FF)
    • Free float is the time a task can be delayed without impacting the next dependent task. 
  • Total float (TF)
    • Total float is the time a task can be delayed without impacting the project deadline.

Float is calculated by determining the time between an activity’s earliest start (ES) and the latest start (LS). Float is also the time between the earliest finish (EF) and the latest finish (LF) of an activity.

Float provides flexibility in the project schedule by defining when activity delays will least affect the project’s finish date.


What is the easiest way to identify that a task belongs on the critical path?

The easiest way to identify tasks on the critical path is by looking at the float value for the task. If the task’s float value is zero, then the task is on the critical path and is now defined as a critical activity.

Identifying critical activities is vital because they directly affect the project schedule. Any delay in critical activities also delays the schedule. 

Critical activities are also important because if the project is running behind schedule, the critical activities are where the project manager should focus. 

Compressing or accelerating critical activities on the schedule is the project manager’s greatest opportunity to reclaim lost time.

Putting it all together:
How do project managers work with the critical path method?

CPM is a highly visual approach to project management that relies on several visual performance management (VPM) tools.

Visual performance management (VPM) tools give project managers and stakeholders crucial performance feedback at a glance by adhering to the 1-3-10 principle: 

  • One second to know whether the project is ahead or behind, 
  • Three seconds to identify where the project is ahead or behind, and 
  • Ten seconds to determine a course of corrective action. 

What are the VPM tools used in the critical path method?

Mapping out the critical path by hand is time-consuming. And to be effective, the critical path schedule must be updated throughout the project.

Project management software makes this easy by automating the CPM process and providing the visual performance management tools that make the CPM process so effective.

Project management software includes tools for decomposing projects into phases and creating the work breakdown structures and dependencies that drive the critical path schedule.

Entering data into the WBS tool generates a Gantt chart that shows dependencies, time durations, and project progress from start to finish.

After setting the schedule, project managers can set the project baseline, milestones, and deadlines. 

And the software connects the work packages to the project budget to monitor expenditures and performance as the project progresses.


The critical path method is essential for project management, and software makes it easy

Project status reporting is a crucial component of the critical path strategy. 

Project managers need specific details presented in easy-to-read dashboards to assess project performance. Project management software is perfect for this.

PM software quickly generates easy-to-understand reports on critical path status, task progress, overall project status, budget alignment, costs, and resource availability

The software does all the calculations, and users can filter the results to show just what they need to see, all with one click.

Construction project management software for successful project management

Successful construction professionals stay on top of every aspect of their projects, from initiation through closeout. 

Construction project management software streamlines these complex processes, manages task-based workflows, and allows seamless communication for a successful project. 

Get a custom demonstration of the Linarc project management system today—the intelligent, intuitive, easy-to-use tool for managing the complexity of today’s building projects.

Connect – Build – Thrive with Linarc