What is the critical path method (CPM)? – The critical path method (CPM) is a technique where you identify tasks that are necessary for project completion and determine scheduling flexibilities. A critical path in project management is the longest sequence of activities that must be finished on time in order for the entire project to be complete.
Any delays in critical tasks will delay the rest of the project. CPM revolves around discovering the most important tasks in the project timeline, identifying task dependencies, and calculating task durations. CPM was developed in the late 1950s as a method to resolve the issue of increased costs due to inefficient scheduling.
Since then, CPM has become popular for planning projects and prioritizing tasks. It helps you break down complex projects into individual tasks and gain a better understanding of the project’s flexibility. Create a critical path method template
Contents
- 1 How is CPM used in construction?
- 2 What is CPM explain with example?
- 3 What are the benefits of CPM?
- 4 What is the role of a CPM?
- 5 Why is it called CPM?
- 6 Where is CPM generally used?
- 7 Is CPM a project management tool?
- 8 What is a good average CPM?
- 9 What is difference between CPM and PERT?
- 10 What is the difference between CPM and CPM?
What does CPM mean in construction?
What is Critical Path Method (CPM) Scheduling? – Critical Path Method (CPM) Scheduling is the most widely used scheduling technique in the Transportation market. This scheduling technique is used to plan and control a project and to calculate the minimum completion time for a project along with the possible start and finish times for the project activities. Critical Path Method relative to the process of making an omelet. Critical tasks have a ‘zero run-time reserve,’ meaning if the duration of these tasks changes, the terms of the entire project will be shifted, resulting in negative monetary impacts and potential risks. Therefore, critical tasks in project management require special control and timely detection of risks.
How is CPM used in construction?
PERT in CPM – At almost the same time that CPM was developed, the Special Projects Office of the United States Navy, with Booz, Hamilton, and Allen as consultants, was developing the Program Evaluation and Review Technique (PERT) for planning and controlling weapons systems development.
PERT is basically a variation of the CPM with a more questioning view of activity time estimates. Time variance is not really accounted for in the critical path method. PERT, however, focuses on more realistic completion time. PERT is used in the critical path method to generate a more realistic timeframe for our project.
To use PERT in your CPM, you need the estimate of the shortest possible duration for each activity (O), the most likely length of time (M), and the longest time it will take if the activity lasts longer than presumed (P). By using this information in the formula, you get a better estimate of your completion time: The critical path method is the most effective and most reliable technique in construction planning.
What is CPM explain with example?
Critical Path Method Definition – The Critical Path Method is defined in the Project Management Body of Knowledge (PMBOK) as follows: “The Critical Path Method is the sequence of scheduled activities that determines the duration of the project.” These scheduled activities must be performed if the project is to be considered a success.
Moreover, they must be completed in a specific order. If you’re building a house, you can’t construct the walls and then dig the foundation; you have to do it in a sequence. The important bit to understand is that the CPM describes the longest sequence of tasks in the project. That is, in any project, you’ll have multiple task sequences.
The CPM would describe the sequence that takes the most time. For example, if you’re building a house, you would have several task sequences as follows: Each task takes a different amount of time and resources. It takes more time to build walls and lay the roof than to install faucets and fixtures. If you had to figure out the project’s ‘Critical Path’, you would look at the sequence that takes the most amount of time, like this: The total time taken to complete the sequence along this critical path would give you an idea of the project’s minimum duration. You might undertake several task sequences simultaneously, but if there are any delays in the critical path sequence, your project will suffer delays as well.
How do you calculate CPM in project management?
Calculating Late Start (LS) and Late Finish (LF) – We have calculated the Early Start and Early Finish dates of all activities. Now it is time to calculate the Late Start and Late Finish dates. The Late Finish date of the last activity on all paths will be the same because no activities can continue once the project is completed. The formula used for Late Start and Late Finish dates:
- Late Start of Activity = Late Finish of activity – activity duration + 1
- Late Finish of Activity = Late Start of successor activity – 1
To calculate the Late Start and Late Finish, we use the backward pass; i.e., we will start from the last activity and move back towards the first activity.
What is CPM in project planning?
What is the critical path method (CPM)? – The critical path method (CPM) is a technique where you identify tasks that are necessary for project completion and determine scheduling flexibilities. A critical path in project management is the longest sequence of activities that must be finished on time in order for the entire project to be complete.
- Any delays in critical tasks will delay the rest of the project.
- CPM revolves around discovering the most important tasks in the project timeline, identifying task dependencies, and calculating task durations.
- CPM was developed in the late 1950s as a method to resolve the issue of increased costs due to inefficient scheduling.
Since then, CPM has become popular for planning projects and prioritizing tasks. It helps you break down complex projects into individual tasks and gain a better understanding of the project’s flexibility. Create a critical path method template
What’s CPM stand for?
CPM (cost per mille) is a paid advertising option where companies pay a price for every 1,000 impressions an ad receives. An “impression” refers to when someone sees a campaign on social media, the search engines or another marketing platform. The CPM pricing structure is essential for businesses that manage affiliate networks.
What are the benefits of CPM?
Advantages & Disadvantages of Critical Path Method Smartsheet Contributor May 5, 2022 The critical path method (CPM) is a scheduling technique for large or complex projects that can help project managers stay on task and under budget. On this page, you’ll find a comprehensive list of and of using CPM, as well as a to help you determine if CPM is right for your project.
For project managers, the critical path is the longest sequence of dependent tasks in a project. By identifying the critical path, project managers can more easily prioritize tasks, build realistic schedules, keep projects within budget, and reduce or offset delays. Project managers can determine the total duration of the project by calculating the time between the start of the first task and the end of the last item on the critical path.
Any tasks that are independent or that belong to a shorter chain of dependent tasks do not add to the total project duration and are therefore not on the critical path. The critical path is the core concept of the (CPM), a scheduling and project management technique that was first developed in the 1950s.
- While the critical path method is still most commonly used for managing, aerospace, and defense systems projects, its core principles are applicable to any sector.
- When project managers anticipate delays using the critical path, they are more likely to keep projects within budget.
- Whether you incur penalties for late delivery, need to expedite shipping, or suddenly require additional staff, unexpected delays are almost always costly.
By reviewing the critical path, project managers can find ways to compensate for delays and anticipate additional resource needs that should be factored into the budget. Tasks on the critical path follow four kinds of dependencies: finish to start, finish to finish, start to start, and start to finish.
- In the case of finish to start, a team cannot begin work on one task until the previous task is completed.
- For example, when constructing a building, workers must pour the foundation before they can begin framing, so foundation pouring and framing are two dependent tasks on the critical path.
- Taken together, these tasks create a chain of interdependent activities that must occur in a certain order to achieve the project objective.
Project managers refer to and update the critical path schedule frequently when a project is underway. Critical path network diagrams and help project managers create clear visual representations of project timelines, so teams can quickly access and understand important information.
Critical path timelines often appear as, which are useful visual tools for communicating dependencies, concurrent work, progress, and milestones. To learn more about, see this comprehensive guide. Lastly, identifying your critical path is important if and when legal disputes arise. When contractors and owners do not agree on who is responsible for delays, or whether a delay or cost overrun triggers contract penalty clauses, clear critical path documentation can serve as important evidence and protect you and your company from liability.
What is the Critical Path Method (CPM)? PM in Under 5 minutes
The critical path method is a reliable way for project managers to budget time and allocate resources. Advantages of CPM include improved accuracy and flexibility in scheduling, clearer communication between project managers and stakeholders, easier task prioritization, and more. Bill Pepoon, Managing Partner and Founder of, says that on a typical commercial building project, only about 20 percent of the activities are on the critical path. The crew may be accomplishing a lot of the remaining 80 percent, but unless they are completing the critical path work, they are falling behind.
- Critical path keeps you on target and makes clear what you need to do to stay on schedule,” Pepoon explains.
- Without identifying and prioritizing those activities, construction managers may have a false sense of progress.
- When I ask if they have done enough work to stay on schedule,” he says, “they are often surprised.
If you can’t demonstrate that you made progress on that 20 percent of the work, you have lost time.” Below are the key benefits that project managers can expect from adopting the critical path method:
Stronger Communication: Critical path method schedules require input from key players across all stages of a project lifecycle. Bringing together the expertise of various team members and subcontractors, from architects to electricians to construction managers, makes the schedule more realistic and robust from the start. Easier Prioritization: Identifying the critical path helps project managers clarify priorities and determine the float of each task. Float, also known as slack, measures how long a task can be delayed before it impacts the completion date. Critical path tasks have zero float, while non-critical activities have positive float. Determining the float of each task helps teams assess priorities. The lower the float, the higher the priority. Improved Accuracy in Scheduling: The critical path method is a popular and reliable tool for improving the accuracy of project schedules. Many project managers use CPM in conjunction with the Program Evaluation and Review Technique (), another project management tool that helps teams estimate total project duration. While CPM focuses on predictable activities, PERT factors in unpredictable events, creating three possible timelines: most optimistic, most pessimistic, and most realistic. By using both PERT and CPM, project managers can create the most accurate forecasts possible. Better Risk Detection: Critical path schedules make clear the relationships between dependent tasks, so project managers can better predict the knock-on effects of a delay. CPM prevents more surprises and offers earlier opportunities to make corrections than other methods that do not track dependencies. Greater Adaptability: When work does not go to plan, CPM network diagrams give project managers the tools to quickly rework the schedule. Certain software programs can even model the effects of different adjustments, so project managers can compare outcomes and select the most beneficial option. By using software, says Pepoon, “You can recalculate the schedule in a fraction of a second.” More Visual Impact: CPM network diagrams and Gantt chart representations of critical path schedules give project managers a quick understanding of a project’s timeline and progress. By referring to these visual tools, project managers and team members can develop a more intuitive understanding of a project’s trajectory than they might with a less visually dynamic option.
Despite these advantages, the critical path method has drawbacks, such as its inability to capture resource constraints. While CPM software can reduce manual work, it also requires complex research and might not be suitable for all project types. Below are some of the most common disadvantages to using the critical path method:
Increased Complexity: The critical path method involves complex calculations with many moving parts. While software can automate the calculations, inputting accurate information requires detailed research and does not eliminate the risk of human error. “You can’t be overly trusting. You have to independently verify the schedule that results,” Pepoon notes. “Every day I find conflicts and anomalies.” Decreased Applicability: Not all project types lend themselves to the critical path method. For example, CPM requires that timelines be predictable and repeatable. CPM is not a good fit for creative projects, such as product design or research tasks, that often come together in unpredictable ways. At the other end of the spectrum, repetitive or independent activities are not well suited to CPM. For example, a weekly maintenance program may involve cleaning dozens of machines, but the order in which the machines are serviced does not matter. In this scenario, CPM does not add value because there are no task dependencies, so there is no critical path. Reduced Attention to High-Float Tasks: When using the critical path method, project managers focus on critical path tasks. While the critical path does determine total project duration, using this method can make it easier to ignore non-critical or high-float tasks, thus resulting in delays. For example, installing the electrical system in a new building is not on the critical path because this can occur during a large window of time. However, if project managers forget about wiring work or delay it too long, it will still impact the completion date. Less Insight Into Resource Constraints: Another drawback of the critical path method is that it does not give good insight into how resource constraints affect project scheduling. The network diagram and CPM schedule do not take into account the availability of equipment or labor resources. At the same time, CPM does not highlight overlap of resource use, which can result in congestion. For example, overlaps in the schedule might mean too many workers in a server center or too much heavy machinery on a construction site. Unnoticed overlaps might also cause trade stacking, which is when multiple tradespeople, such as electricians and plumbers, try to work in the same location simultaneously, potentially causing delays, safety hazards, and unforeseen costs. These problems compound when a company has multiple projects underway and must coordinate resources among them. CPM on its own is not helpful for spotting these issues. Project managers will need to solicit the expertise of other professionals and resource-based scheduling techniques to gain necessary insight into resource management.
| Advantages | Disadvantages |
|---|---|
| Incorporates knowledge of all stakeholders | Complex |
| Better work prioritization | Resource intensive |
| Greater accuracy | Only useful for certain project types |
| Helps spot problems early | Makes it harder to see issues with non-critical tasks |
| Makes schedule easier to adapt | Does not account for resource constraints |
| Visual | Steep learning curve |
While the critical path method can help project managers prioritize tasks for many projects, it is not always the appropriate solution. It is important to evaluate your project in advance and determine whether CPM will add value to your project. The following are some key considerations when deciding whether the critical path method is right for your project:
Customer Requirements: Does your customer demand a CPM schedule? With certain clients, such as large government agencies and public entities, producing a critical path schedule is mandatory. These projects often entail large investments and require project controls such as CPM that give the commissioning client oversight of progress. If the client demands CPM, then you have no choice but to use it. Contractual Obligations: Does your contract include penalty clauses that require CPM documentation? Contracts for expensive and time-sensitive projects often contain clauses that impose penalties on contractors for delays, unless the contractor can prove that delays were caused by uncontrollable factors or that the client is at fault. If a contract specifies that a CPM schedule is the basis for substantiating claims and counterclaims, then project managers will need to implement CPM. Even when contracts do not specify this, courts usually recognize CPM as legitimate, so it is a good idea to use CPM scheduling when delays might have financial or legal repercussions. Work Predictability: Is the work novel or undefined? The critical path method relies on precise forecasts of task duration. A project that is novel, or involves tasks that have never been done before, and projects with uncertain rates of production, such as creative projects, are not a good match for CPM. Similarly, projects that require managers to define the work as they progress, such as discovery or research projects, are ill suited to CPM scheduling. Deadlines: Does the project have a critical completion date? The greatest strengths of CPM scheduling are its accuracy and potential to allow project planners to adapt to changes without impacting completion dates. If the completion date is flexible, then project managers should avoid the complex and time-consuming process of using CPM. Task Dependencies: Do tasks need to be completed in a specific order? In order for project managers to create a critical path, projects need to have task dependencies. If the project does not have a critical order of activities, then CPM will not add value to the project. Project Value and Duration: Does the project have a high value? Will the project duration exceed six weeks? Producing and managing a critical path schedule is resource intensive, so project managers should only apply CPM to projects that have a significant scope, duration, and value. While there are exceptions, a good candidate for CPM is typically a project that is complex and lasts at least a few months. These projects generally involve multiple work streams and specialized labor or subcontractors. In terms of cost, according to pros such as Bill Pepoon and purchasing guidelines or contracting requirements for government agencies, budgets upward of $750,000 or $1 million usually justify CPM. Some public agencies set a minimum contract threshold, often $1 million, that requires a CPM schedule. The right number is relative to the size, funding, and financial risks of a project. For example, a startup company or small business that risks going out of business if it faces legal or financial consequences from delays may opt for CPM even if the budget is below $1 million.
For additional help deciding whether the critical path method is right for your project, you can work through the following decision tree. While there may be other reasons to use CPM, such as applying it to simple projects as a learning experience, this decision tree will be a helpful guide in most cases. From simple task management and project planning to complex resource and portfolio management, Smartsheet helps you improve collaboration and increase work velocity – empowering you to get more done. The Smartsheet platform makes it easy to plan, capture, manage, and report on work from anywhere, helping your team be more effective and get more done.
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: Advantages & Disadvantages of Critical Path Method
What are the types of CPM?
3 Types of CPM: vCPM, eCPM, and CPCV.
What is the role of a CPM?
Construction Project Managers (CPMs) are specialized project managers who assist in the design, contracting and construction of new and rehabilitative building projects. CPM’s work to implement efficient building practices that span a project from design to completion.
Why is it called CPM?
What CPM Means? – In online advertising and digital marketing, CPM is the cost-per-thousand-impressions or simply the price a marketer would pay to receive 1,000 campaign impressions. CPM actually stands for “cost per mille” — not like a rental car’s cost per mile, but cost per mille with two Ls — which means “thousand” in Latin. 
CPM is a way to measure marketing expenses for large numbers of impressions. It’s like shorthand, since expressing individual costs per impression would become tedious and, in many cases, represent fractions of a penny. As mobile marketers, we must understand our campaign costs closely and have the growth to justify the CPM.
Where is CPM generally used?
Project managers frequently face the task of controlling projects that contain unknown and unpredictable factors. When the projects are not complex, bar charts can be used to plan and control project activities. These charts divide the project into discrete activities or tasks and analyze each task individually to indicate weekly manpower requirements.
As the work goes forward, progress is charted and estimates are made on the effects of any delays or difficulties encountered during the completion of the project. In the mid-1950s more sophisticated methods of project planning and control were developed. Two systems based on a network portrayal of the activities that make up the project emerged at about the same time.
PERT ( Program Evaluation and Review Technique ) was first used in the development of submarines capable of firing Polaris missiles. CPM (the Critical Path Method ) was used to manage the annual maintenance work in an oil and chemical refinery. Many variations and extensions of the two original techniques are now in use, and they have proved particularly valuable for projects requiring the coordinated work of hundreds of separate contractors.
The use of project planning and control techniques based on PERT or CPM are now common in all types of civil engineering and construction work, as well as for large developmental projects such as the manufacture of aircraft, missiles, space vehicles, and large mainframe computer systems. A simple example of a network, or “arrow diagram,” used in developing an electronic component for a complex system, is shown in the figure,
Each circle on the diagram represents a task or well-defined activity that is part of the project. The number in each circle represents the expected time required to complete the task. Task A requires two weeks to complete and might, for example, represent the development of general specifications for an electronic unit in question.
Tasks B and E might represent two related parts of the design of the unit’s power supply, C and F the design of the main functional circuits, and D and G the design of the control circuitry. Arrows indicate the precedence of relationships and depict which tasks must be completed before subsequent tasks can begin.
In this example, tasks B, C, and D cannot be started until A has been completed (that is, no one can design specific component items before the general specifications are agreed upon). Task H requires two weeks to complete but cannot be started until the designs of the power supply and the functional and control circuits have been completed.
- This task might represent the design of the unit’s case or cover, and the case cannot be made final until all of the component designs are completed.
- The arrow diagram is an invaluable planning aid for determining how long a project will take to complete.
- Adding all of the task times together in the example indicates that there are 24 weeks of work to be completed.
Note, however, that several tasks can be done simultaneously. For example, once task A has been completed, B, C, and D can be started and worked on concurrently. Thus, the earliest completion date can be determined by looking at all possible “paths” through the network and choosing the longest one, or the one with tasks requiring the most total time.
In this example the longest, or “critical,” path is A–C–F–H, requiring a total time of 11 weeks. The arrow diagram yields additional information to the project planner. The earliest possible time that task H can be started is nine weeks after the start of the project (that is, after tasks A, C, and F have been completed).
When task A is completed at the end of week 2, tasks B and E do not have to be started immediately in order to complete the project in the minimum possible time; B and E each have three weeks of “slack.” The diagram shows that if activity B is started three weeks later than its earliest possible start time (at week 5), it would be completed at the end of week 5; E would then start at the beginning of week 6 and be completed in time for H to begin at its earliest time, the beginning of week 10.
The notion of slack in a project network is a powerful concept that allows planners to schedule scarce resources efficiently and manage people and equipment so that critical activities are kept on schedule and slack activities are delayed without placing the project in jeopardy. This simple example is based on CPM logic; it uses single-point task time estimates and assumes that the completion time for the project is the simple sum of the task times along the critical path.
PERT logic assumes probabilistic estimates for each task time, with pessimistic, realistic, and optimistic estimates for the completion times of each task. In actual projects the relationships among the required tasks are often complex, and the arrow diagram for the project might cover the entire wall of an office.
- Even though it is a time-consuming job to work out arrow diagrams, precedence relationships, task time estimates, and so on for large projects, CPM or PERT is an invaluable aid to planning and control.
- The proliferation of computer programs that handle critical path and slack time calculations and the development of computer systems capable of handling cost estimates, budget control, resource allocation, and time scheduling promise to make CPM and PERT even more valuable than in the past.
William K. Holstein
Is CPM a project management tool?
CPM or the Critical Path Method is an algorithm used in project management that is used to schedule project activities. The critical path refers to the longest stretch of the activities, and a measure of them from start to finish. With the help of CPM, we’ll be able to create a model that enables you to determine the following:
Tasks required to complete the project Dependencies between tasks The duration required to complete an activity
Now, before we can get started with CPM or Critical Path Method, we’ll have to understand two major concepts which are Events and Activities. To help understand them better, let’s have a look at the network diagram (which is also the output) of the process. This output represents some of the most important parts of the process: Events and Activities.
What is a good average CPM?
OFFLINE/TRADITIONAL ADVERTISING COSTS IN 2021
| Platform | Average CPM |
|---|---|
| Magazine | $140-$1,300 |
| Newspaper | $10-45 |
| Direct Mail | $500-1,000 |
| Network TV | $20-30 |
How do you calculate CPM example?
How to calculate cost per thousand – To calculate your cost per thousand, you need to take the total cost of your online advertising divided by the total number of impressions and times 1000. For example, if your ad campaign costs you $500 for 100 000 impressions, your CPM would be $5.
What is a CPM Calculator?
The CPM Calculator is used to calculate the CPM (cost per 1,000 impressions) based on the total campaign budget and number of impressions. Also, the calculator allows you to calculate total budget or number of impressions based on the other two values.
What does CPM stand for in BIM?
CPM & BIM | Advanced Fast Track Summer Training on Construction Project Management (CPM) & Building Information Modelling (BIM)
What is difference between CPM and PERT?
Difference Between PERT and CPM – GeeksforGeeks
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1. : PERT is appropriate technique which is used for the projects where the time required or needed to complete different activities are not known. PERT is majorly applied for scheduling, organization and integration of different tasks within a project.
- It provides the blueprint of project and is efficient technique for project evaluation,2.
- CPM is a technique which is used for the projects where the time needed for completion of project is already known.
- It is majorly used for determining the approximate time within which a project can be completed.
Critical path is the largest path in project management which always provide minimum time taken for completion of project Difference between PERT and CPM :
| S.No. | PERT | CPM |
|---|---|---|
| 1. | PERT is that technique of project management which is used to manage uncertain (i.e., time is not known) activities of any project. | CPM is that technique of project management which is used to manage only certain (i.e., time is known) activities of any project. |
| 2. | It is event oriented technique which means that network is constructed on the basis of event. | It is activity oriented technique which means that network is constructed on the basis of activities. |
| 3. | It is a probability model. | It is a deterministic model. |
| 4. | It majorly focuses on time as meeting time target or estimation of percent completion is more important. | It majorly focuses on Time-cost trade off as minimizing cost is more important. |
| 5. | It is appropriate for high precision time estimation. | It is appropriate for reasonable time estimation. |
| 6. | It has Non-repetitive nature of job. | It has repetitive nature of job. |
| 7. | There is no chance of crashing as there is no certainty of time. | There may be crashing because of certain time boundation. |
| 8. | It doesn’t use any dummy activities. | It uses dummy activities for representing sequence of activities. |
| 9. | It is suitable for projects which required research and development. | It is suitable for construction projects. |
Difference Between PERT and CPM – GeeksforGeeks
What is the difference between CPM and CPM?
What is eCPM? – eCPM stands for effective cost-per-thousand impressions, or effective “Cost Per Mille”. Both eCPM and CPM illustrate the ad revenue generated by the publisher from 1000 ad impressions. The main difference is that eCPM is the average of multiple CPMs.
- Because many advertisers are bidding on each ad impression with different CPMs, the price isn’t fixed.
- ECPM gives you the combined average of all advertiser bids for your ad impressions.
- Some of your ad inventory can even be purchased via different bidding models, for example, CPC,
- Therefore, eCPM helps to learn how much you can earn across all bidding models.
The higher the eCPM, the higher the total ad revenue for the publisher. Related Article: How to Increase Ad Revenue | Success Formula and Proven Solutions
What does CPM mean when buying a house?
Certified Property Manager ® (CPM®)
What is a good CPM?
What is a good CPM? – A good cost per mille depends on multiple factors, such as the type of ad networks you use (Google ads, display ads, search ads, Facebook ads, etc) Google search ads average CPM is $38.40, while the google display network ads have an average CPM of $3.12.
Why is CPM important in project management?
Advantages & Disadvantages of Critical Path Method Smartsheet Contributor May 5, 2022 The critical path method (CPM) is a scheduling technique for large or complex projects that can help project managers stay on task and under budget. On this page, you’ll find a comprehensive list of and of using CPM, as well as a to help you determine if CPM is right for your project.
- For project managers, the critical path is the longest sequence of dependent tasks in a project.
- By identifying the critical path, project managers can more easily prioritize tasks, build realistic schedules, keep projects within budget, and reduce or offset delays.
- Project managers can determine the total duration of the project by calculating the time between the start of the first task and the end of the last item on the critical path.
Any tasks that are independent or that belong to a shorter chain of dependent tasks do not add to the total project duration and are therefore not on the critical path. The critical path is the core concept of the (CPM), a scheduling and project management technique that was first developed in the 1950s.
While the critical path method is still most commonly used for managing, aerospace, and defense systems projects, its core principles are applicable to any sector. When project managers anticipate delays using the critical path, they are more likely to keep projects within budget. Whether you incur penalties for late delivery, need to expedite shipping, or suddenly require additional staff, unexpected delays are almost always costly.
By reviewing the critical path, project managers can find ways to compensate for delays and anticipate additional resource needs that should be factored into the budget. Tasks on the critical path follow four kinds of dependencies: finish to start, finish to finish, start to start, and start to finish.
In the case of finish to start, a team cannot begin work on one task until the previous task is completed. For example, when constructing a building, workers must pour the foundation before they can begin framing, so foundation pouring and framing are two dependent tasks on the critical path. Taken together, these tasks create a chain of interdependent activities that must occur in a certain order to achieve the project objective.
Project managers refer to and update the critical path schedule frequently when a project is underway. Critical path network diagrams and help project managers create clear visual representations of project timelines, so teams can quickly access and understand important information.
Critical path timelines often appear as, which are useful visual tools for communicating dependencies, concurrent work, progress, and milestones. To learn more about, see this comprehensive guide. Lastly, identifying your critical path is important if and when legal disputes arise. When contractors and owners do not agree on who is responsible for delays, or whether a delay or cost overrun triggers contract penalty clauses, clear critical path documentation can serve as important evidence and protect you and your company from liability.
What is the Critical Path Method (CPM)? PM in Under 5 minutes
The critical path method is a reliable way for project managers to budget time and allocate resources. Advantages of CPM include improved accuracy and flexibility in scheduling, clearer communication between project managers and stakeholders, easier task prioritization, and more. Bill Pepoon, Managing Partner and Founder of, says that on a typical commercial building project, only about 20 percent of the activities are on the critical path. The crew may be accomplishing a lot of the remaining 80 percent, but unless they are completing the critical path work, they are falling behind.
Critical path keeps you on target and makes clear what you need to do to stay on schedule,” Pepoon explains. Without identifying and prioritizing those activities, construction managers may have a false sense of progress. “When I ask if they have done enough work to stay on schedule,” he says, “they are often surprised.
If you can’t demonstrate that you made progress on that 20 percent of the work, you have lost time.” Below are the key benefits that project managers can expect from adopting the critical path method:
Stronger Communication: Critical path method schedules require input from key players across all stages of a project lifecycle. Bringing together the expertise of various team members and subcontractors, from architects to electricians to construction managers, makes the schedule more realistic and robust from the start. Easier Prioritization: Identifying the critical path helps project managers clarify priorities and determine the float of each task. Float, also known as slack, measures how long a task can be delayed before it impacts the completion date. Critical path tasks have zero float, while non-critical activities have positive float. Determining the float of each task helps teams assess priorities. The lower the float, the higher the priority. Improved Accuracy in Scheduling: The critical path method is a popular and reliable tool for improving the accuracy of project schedules. Many project managers use CPM in conjunction with the Program Evaluation and Review Technique (), another project management tool that helps teams estimate total project duration. While CPM focuses on predictable activities, PERT factors in unpredictable events, creating three possible timelines: most optimistic, most pessimistic, and most realistic. By using both PERT and CPM, project managers can create the most accurate forecasts possible. Better Risk Detection: Critical path schedules make clear the relationships between dependent tasks, so project managers can better predict the knock-on effects of a delay. CPM prevents more surprises and offers earlier opportunities to make corrections than other methods that do not track dependencies. Greater Adaptability: When work does not go to plan, CPM network diagrams give project managers the tools to quickly rework the schedule. Certain software programs can even model the effects of different adjustments, so project managers can compare outcomes and select the most beneficial option. By using software, says Pepoon, “You can recalculate the schedule in a fraction of a second.” More Visual Impact: CPM network diagrams and Gantt chart representations of critical path schedules give project managers a quick understanding of a project’s timeline and progress. By referring to these visual tools, project managers and team members can develop a more intuitive understanding of a project’s trajectory than they might with a less visually dynamic option.
Despite these advantages, the critical path method has drawbacks, such as its inability to capture resource constraints. While CPM software can reduce manual work, it also requires complex research and might not be suitable for all project types. Below are some of the most common disadvantages to using the critical path method:
Increased Complexity: The critical path method involves complex calculations with many moving parts. While software can automate the calculations, inputting accurate information requires detailed research and does not eliminate the risk of human error. “You can’t be overly trusting. You have to independently verify the schedule that results,” Pepoon notes. “Every day I find conflicts and anomalies.” Decreased Applicability: Not all project types lend themselves to the critical path method. For example, CPM requires that timelines be predictable and repeatable. CPM is not a good fit for creative projects, such as product design or research tasks, that often come together in unpredictable ways. At the other end of the spectrum, repetitive or independent activities are not well suited to CPM. For example, a weekly maintenance program may involve cleaning dozens of machines, but the order in which the machines are serviced does not matter. In this scenario, CPM does not add value because there are no task dependencies, so there is no critical path. Reduced Attention to High-Float Tasks: When using the critical path method, project managers focus on critical path tasks. While the critical path does determine total project duration, using this method can make it easier to ignore non-critical or high-float tasks, thus resulting in delays. For example, installing the electrical system in a new building is not on the critical path because this can occur during a large window of time. However, if project managers forget about wiring work or delay it too long, it will still impact the completion date. Less Insight Into Resource Constraints: Another drawback of the critical path method is that it does not give good insight into how resource constraints affect project scheduling. The network diagram and CPM schedule do not take into account the availability of equipment or labor resources. At the same time, CPM does not highlight overlap of resource use, which can result in congestion. For example, overlaps in the schedule might mean too many workers in a server center or too much heavy machinery on a construction site. Unnoticed overlaps might also cause trade stacking, which is when multiple tradespeople, such as electricians and plumbers, try to work in the same location simultaneously, potentially causing delays, safety hazards, and unforeseen costs. These problems compound when a company has multiple projects underway and must coordinate resources among them. CPM on its own is not helpful for spotting these issues. Project managers will need to solicit the expertise of other professionals and resource-based scheduling techniques to gain necessary insight into resource management.
| Advantages | Disadvantages |
|---|---|
| Incorporates knowledge of all stakeholders | Complex |
| Better work prioritization | Resource intensive |
| Greater accuracy | Only useful for certain project types |
| Helps spot problems early | Makes it harder to see issues with non-critical tasks |
| Makes schedule easier to adapt | Does not account for resource constraints |
| Visual | Steep learning curve |
While the critical path method can help project managers prioritize tasks for many projects, it is not always the appropriate solution. It is important to evaluate your project in advance and determine whether CPM will add value to your project. The following are some key considerations when deciding whether the critical path method is right for your project:
Customer Requirements: Does your customer demand a CPM schedule? With certain clients, such as large government agencies and public entities, producing a critical path schedule is mandatory. These projects often entail large investments and require project controls such as CPM that give the commissioning client oversight of progress. If the client demands CPM, then you have no choice but to use it. Contractual Obligations: Does your contract include penalty clauses that require CPM documentation? Contracts for expensive and time-sensitive projects often contain clauses that impose penalties on contractors for delays, unless the contractor can prove that delays were caused by uncontrollable factors or that the client is at fault. If a contract specifies that a CPM schedule is the basis for substantiating claims and counterclaims, then project managers will need to implement CPM. Even when contracts do not specify this, courts usually recognize CPM as legitimate, so it is a good idea to use CPM scheduling when delays might have financial or legal repercussions. Work Predictability: Is the work novel or undefined? The critical path method relies on precise forecasts of task duration. A project that is novel, or involves tasks that have never been done before, and projects with uncertain rates of production, such as creative projects, are not a good match for CPM. Similarly, projects that require managers to define the work as they progress, such as discovery or research projects, are ill suited to CPM scheduling. Deadlines: Does the project have a critical completion date? The greatest strengths of CPM scheduling are its accuracy and potential to allow project planners to adapt to changes without impacting completion dates. If the completion date is flexible, then project managers should avoid the complex and time-consuming process of using CPM. Task Dependencies: Do tasks need to be completed in a specific order? In order for project managers to create a critical path, projects need to have task dependencies. If the project does not have a critical order of activities, then CPM will not add value to the project. Project Value and Duration: Does the project have a high value? Will the project duration exceed six weeks? Producing and managing a critical path schedule is resource intensive, so project managers should only apply CPM to projects that have a significant scope, duration, and value. While there are exceptions, a good candidate for CPM is typically a project that is complex and lasts at least a few months. These projects generally involve multiple work streams and specialized labor or subcontractors. In terms of cost, according to pros such as Bill Pepoon and purchasing guidelines or contracting requirements for government agencies, budgets upward of $750,000 or $1 million usually justify CPM. Some public agencies set a minimum contract threshold, often $1 million, that requires a CPM schedule. The right number is relative to the size, funding, and financial risks of a project. For example, a startup company or small business that risks going out of business if it faces legal or financial consequences from delays may opt for CPM even if the budget is below $1 million.
For additional help deciding whether the critical path method is right for your project, you can work through the following decision tree. While there may be other reasons to use CPM, such as applying it to simple projects as a learning experience, this decision tree will be a helpful guide in most cases. From simple task management and project planning to complex resource and portfolio management, Smartsheet helps you improve collaboration and increase work velocity – empowering you to get more done. The Smartsheet platform makes it easy to plan, capture, manage, and report on work from anywhere, helping your team be more effective and get more done.
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: Advantages & Disadvantages of Critical Path Method
