What Is a Critical Path Analysis?

As defined, the critical path analysis, also known as the critical path method, is a scheduling procedure that employs a network diagram to depict a project and the sequences of tasks needed to complete it, which are referred to as paths. Once the paths are defined, an algorithm calculates the duration of each path to identify the critical path, which determines the total duration of the project. Similar to Gantt charts, a critical path analysis will help you to plan all tasks that need to be accomplished as part of the project.

A critical path analysis will also serve as the foundation for both the creation of a schedule and the allocation of resources. They allow you to track the progress of a project’s objectives while it is being managed. They assist you in determining where corrective action is required to get a project back on track.

Important Elements of a Critical Path Method Schedule

A CPM schedule contains many different elements. Here are the common ones, explained:

Critical Path. The critical path is the longest activity path in the schedule network that predicts when the project will be completed. What does this imply, you may ask? That means that everything we do, whether it’s building a construction project, getting to work, or cooking thanksgiving dinner, has a critical path. The CPM schedule enables us to determine what that critical path is. It is critical to correctly identify the project’s critical path because delays that occur in the project’s critical path will cause the project’s completion to be delayed.Data Date. A data date will be assigned to each CPM schedule. The data date is the starting point for calculating the schedule. That vertical data date line will advance in time over the course of a project (as the project begins and the contractor makes progress). If the CPM schedule is updated monthly, the vertical data date line advances 30 days in time each month. As the project progresses, everything to the left of the vertical data date line will represent the actual start and finish dates of the work, while everything to the right of the data date will project or forecast the start and finish dates of the remaining uncompleted work.Activity Durations. Each activity (usually represented as a bar) in a CPM schedule will have a duration (time). The length of the bar represents how long it takes to complete an activity. The duration of an activity is represented as either the original duration or the remaining duration. They are labeled “OD” for the original duration and “RD.” for the remaining duration. The estimated or planned amount of time required to complete a work activity is referred to as the original duration. Once an activity begins, the remaining duration represents the amount of time it will take the contractor of the project to complete the work.Logic Relationships. The four types of logic relationships are as follows: Finish-to-Start relationships, in which if one activity ends, its successor can begin. A Start-to-Start relationship exists when one activity begins, and its successor can begin. A Finish-to-Finish relationship in which, as one activity concludes, its successor may also conclude, but not until that time. Finally, there is a Start-to-Finish relationship, which means that as one activity begins, its successor can finish.Work Calendars. A CPM schedule must also include work calendars as an essential component. Contractors for a project can perform work on a project in a variety of ways, including how frequently they work and how long they work on a given day. A typical default work calendar is a five-day-per-week, eight-hour-per-day work week. Typically, when you open or prepare a schedule, it is built on that foundation. There are also work activities that only take place on a calendar day.Activity Dates. Another critical component of a CPM schedule is activity dates. Every activity with a duration (meaning it takes more than a day to complete) will have four different types of dates. In most cases, there is an early start, an early finish, a late start, and a late finish date. These are known as early and late dates. These early and late dates are determined by the CPM calculation’s forward and backward passes. The early dates represent the earliest date an activity can start or finish without delaying the project, and the late dates represent the latest date an activity can start or finish without delaying the project.

Advantages Of a Critical Path

Here are the advantages of using critical path analysis in a project; these daily advantages usually benefit the project managers:

Step by Step Process In a Critical Path Analysis

Here are the steps to be used in the critical path analysis; they may be more, they may be less depending on the project that your company is undertaking.

  • 1. Specify Each Activity

    You must use a work breakdown structure in this step to identify each activity (or task) involved in the project. This list of activity specifications should only contain higher-level activities. When using detailed activities, the critical path analysis may become too difficult to manage and maintain. A work breakdown structure divides projects into manageable chunks. The first step is to identify the main project deliverables. Then you can begin to divide the high-level activities into smaller chunks of work.

    You can also customize how your work breakdown structure is displayed. Some people prefer to use a tree structure, while others prefer to use lists or tables. One of the simplest ways to represent a work breakdown structure is with an outline.

  • 2. Establish Dependencies

    Dependencies can also be referred to as activity sequences. Some tasks will be dependent on the completion of others. Listing the activities’ immediate predecessors will assist you in determining the correct order. To correctly identify activities and their precedence, you must first identify the following factors: the other tasks that should occur before this task, the tasks that should be completed at the same time as this task, and the tasks that should occur immediately after this task

  • 3. Create a Network Diagram

    In this step, you can start to draw the critical path analysis chart (CPA), also known as the network diagram, once you’ve identified the activities and their dependencies. The network diagram is a visual representation of the dependencies that govern the order of your activities. This critical path diagram used to be drawn by hand, but now there are software programs that can do it for you.

  • 4. Estimate the Activity Completion Time

    You must now estimate the time required to complete each activity using previous experience or the knowledge of an experienced team member. If you’re in charge of a smaller project, you’ll probably estimate time in days. When working on a large project, you may need to measure time in weeks. If you don’t feel confident in your best-guess estimates, you can use the 3-point estimation method, which is designed to place more emphasis on the most realistic timeframe. Three-point estimation requires you to generate 3 different time estimates for each task based on prior experience or best guesses.

  • 5. Identify the Critical Path

    You can start identifying the critical path in this step. There are two methods for determining the critical path. You can simply look at your network diagram and identify the longest path through the network — that is, the longest sequence of activities on the path. Look for the path with the longest duration in days, not the path with the most boxes or nodes. The Forward Pass/Backward Pass technique can also be used to identify critical activities by identifying the earliest and latest start and finish times for each activity.

    You should also keep in mind that you will encounter network sensitivity if you have multiple critical paths. If the critical path is likely to change once the project begins, the project schedule is considered sensitive. The more critical the paths in a project, the more likely a schedule change will happen.

  • 6. Update the Created Critical Path Diagram to Show Progress

    As the project progresses, you will learn the actual completion times for each activity. This information can then be added to the network diagram (rather than continuing to use estimations). You can recalculate a different critical path by updating the network diagram as new information becomes available. You will also have a more accurate picture of the project’s completion date and will be able to tell if you are on track or falling behind


What is Critical Path Software?

Critical path software is used to calculate the critical path in your project schedule automatically. Managers would have to manually calculate the time-consuming and complicated equation if they did not use the essential software. And, as we all know, time is one of a project’s three constraints, so it’s easy to see why critical path software has become popular in project management. Any opportunity to increase efficiencies moves the project closer to its goals and objectives.

Because critical path is such a specific technique, critical path software is usually associated with a larger project planning tool that organizes tasks, prioritizes the sequence of activities, and includes other features that contribute to the creation of the schedule.

What is a Crash Duration in a project?

The term ‘crash duration’ refers to the shortest amount of time that an activity can be scheduled for. It can be accomplished by directing more resources toward the completion of that activity, resulting in less time spent and, in many cases, lower quality of work because the premium is placed on speed. Crash duration is commonly modeled as a linear relationship between cost and activity duration; however, in many cases, a convex or step function is more appropriate.

What is PERT and how does it differ from a Critical Path Analysis?

A PERT chart, also known as an activity-on-arrow diagram, is a visual representation of your project’s schedule that shows the order of tasks and which can be completed concurrently. A PERT chart contains many of the same details as a critical path method, such as earliest and latest start dates, earliest and latest finish dates, and slack (or float) between activities.

The most significant distinction between the critical path method and PERT is in time estimation. Time variance is not taken into account in the critical path method. You’re estimating completion times based on best-guess estimates, which may change. With PERT, you place more emphasis on the most realistic completion time.

What is “float” in a project task?

Float, also known as slack, is a term that describes how long you can postpone a task before it disrupts the planned schedule and jeopardizes the project’s deadline. The critical path tasks have no float. You can calculate the float using different kinds of project management software. If an activity has a float greater than zero, it can be postponed without affecting the project’s completion time.

Are there any advantages of using Critical Path Software for analysis?

Knowing the critical path and having a tool to recalculate it as your schedule evolves throughout the project are critical to getting back on track when you’re behind schedule. More advantages of using critical path software include quick calculations to save time and effort, tracking progress to know if you’re behind, recalculating as the project schedule changes, keeping track of task dependencies, setting milestones and saving important dates, getting insightful data when planning tasks, and creating a schedule baseline for project variance.

In conclusion, Critical Path Analysis can be a powerful and flexible decision-making tool for large project managers because it is useful at various stages of project management, from initial planning or analyzing alternative programs to scheduling and controlling the jobs (activities) that comprise a project. Using critical path analysis also allows the manager to quickly investigate the effects of crash programs and anticipate potential bottlenecks that may arise as a result of shortening certain critical jobs. Finally, this method yields reasonable estimates of total project costs for various completion dates, allowing the manager to choose the best schedule. In this article, you can find examples of the critical path analysis that you can download and personally use for your own study.