Critical Path Analysis - The Shortest Route To Successful Completion

Critical Path Analysis (CPA) identifies those activities which combine to give the shortest time to reach the end of the project, the Critical Path:

The shortest time possible the project will take as currently defined.

CPA refers to the iterative process needed to identify and challenge critical path activities.

A few other terms commonly used when referring to critical path analysis:

  • Free Float (Free Slack) - refers to the amount of time an activity can be delayed or take, in terms of calendar time, without affecting the scheduling of any other activity in the project.

  • Total Float (Total Slack) - refers to the overall amount of calendar time an activity can be delayed or take without affecting the overall schedule’s critical path and consequently the overall completion date of the project.

  • A critical path activity has a Total Float of 0 (zero)

  • Near Critical Activities - refers to activities that themselves are not part of the schedule’s critical path, yet their Total Float is close to 0 (zero) - it’s common for activities with a Total Float less that the number of days within a project control reporting period to be considered Near Critical Activities.

  • Why is this IMPORTANT?

    Should you take your eye of the ball with these activities, within one reporting period you could suddenly find your project suffering an overall delay due to insufficient progress of an activity not on the original critical path of the project - QUITE EMBARRASSING!

For the entirety of the Successful-Project-Management website, when we refer to the term “Critical Path” we automatically include “Near Critical” activities within the definition.

Just like accounting, successful project management should operate with some degree of prudence!


We are NOT going to show you how to calculate the critical path of a project here.  Knowing how to do that is NOT IMPORTANT with the sophistication of modern project scheduling software available today, which undertake these calculations instantaneously.  What IS IMPORTANT is to understand how to manage the critical paths of your projects.

For the classicists among you, there is a wealth of information available via the internet on how critical path calculations are done mathematically.

Critical Path Drivers

Having identified the critical path activities for your project, it’s worth understanding the main drivers that could cause an activity to sit on the critical path.  The following are some examples of such factors:

  • Estimated activity duration

  • Cash flow restrictions dictating fixed start dates

  • Business operational constraints affecting project workflow

  • The logical sequence identified for progressing activities

  • Calendar restrictions associated with activities

  • Ability to resource activities appropriately

So! A question very frequently asked by stakeholders regarding the overall timeline for a project, and quite common among Finance Directors:

Why can the project not be completed any sooner?

The sooner the project gets completed, the sooner the benefits of the project will be gained.  For commercial organisations, these benefits, more often then not, provide bottom line profitability improvements to the organisation:
  • Revenue streams can be brought on line sooner

  • Efficiency measures can be realised sooner

  • Levels of financing cost for the project can be reduced

  • Less finance may be needed to fund the overall project’soverheads

Rather than just role over to such valid challenges, which is very dangerous from the project’s perspective, it’s important to demonstrate an understanding of the underlying factors that cause tasks to become critical path activities.  By understanding these factors fully, as a Successful Project Manager, you’ll be able to manage stakeholder perceptions and understanding more proactively and with confidence.  Demonstrating you have the initiative! - very important for any Successful Project Manager.

Opportunities for minimising a project’s critical path.

Change the sequencing of activities - if you can carry out your project’s activities in a different sequence to that originally intended, you may be able to shorten the critical path.  Within scheduling software this would be done by changing the logic links between activities in the logic network.


It’s easy to change an activity’s successor logic or predecessor logic and think you’ve got the result you may be looking for - however, how realistic is the new logic sequence in practice?  Theory is often quite different from practical reality. Are you setting yourself up for a fall later?

In order to achieve a shorter overall project timescale, you may have to add more activities  to your software project plan in order to communicate and track a more detailed sequence to tasks.


Seek to stick to start/finish logic links within your critical path analysis, and use more detailed tasks with shorter durations to facilitate this - break the work down to a higher level of detail - This may appear to contradict our philosophy of minimising the level of detail within a project plan and keeping workflows as simple as possible, but in such instances, the extra detail is justified...

By seeking to shorten the critical path, a level of complexity, and ultimately risk, is inevitably introduced to the project.  In order to deliver this shorter timescale, the critical path needs to be controlled and delivered successfully.  Only by being able to efficiently communicate an understanding of the detail of the game plan, will others be able to deliver it successfully.  


The gantt chart is one way to communicate the game plan, but not the only way.  Consider using storyboarding to communicate more complex or intricate sequences within your plan.

Reducing the amount of calendar time needed to carry out an activity - another way to reduce the critical path of a project is to reduce the amount of calendar time it takes to complete a task; reduce its duration - reducing the duration of a critical path activity by a week, you reduce the overall timescale for the project by a week, however...

BEWARE! You may be adding risk to the project, risks need to be properly understood and managed as you progress the project, if you are to avoid trouble.

When working and analysing critical paths, it’s often useful to work in a gantt chart view of your scheduling software, however to be able to see the wood for all the trees use a report filter to show you only those activities that are on the critical path - create a filter to show activities with a Total Float of 0 (zero) OR less than the reporting periods you have chosen to use.

This clearly shows the activities and relationships that determine the critical path.  From here it’s relatively straightforward to systematically review durations or relationship logic in order to seek ways to shorten the overall project timescale.  It’s useful to also have the following fields (columns) turned on in the gantt chart report:

  • Duration

  • Predecessor

  • Successor

  • Total Float

It’s worth ensuring that the estimating accuracy of activity durations is understood, and therefore; how realistic is the activity duration used in the planning network? - by identifying that there appears to be too much time contingency in an activity’s duration, you can investigate how to reduce the duration by carrying out some further, more in depth analysis of the effort required to carry out the activity.

You may also decide to consider changing the working calendar associated with an activity, carrying out work on the task 7 days per week, or perhaps using 2 shifts per day rather than one - however you need to be aware of the additional cost associated with over-time working, or the additional resources needed to facilitate a second working shift. This additional cost may not out weigh the benefit of completing the overall project sooner.

You may also decide to reduce a task’s duration by increasing the number of people working on the task at any point in time, if suitable resources are available, and work faces are able to accommodate the additional resources efficiently.  If a building’s blockwork walls are planned to take 6 weeks with 4 tradesmen, can it be done efficiently in 3 weeks with 8?  

WARNING! The practicalities need to be assessed properly before undertaking such significant changes in the game plan.

Controlling Critical Path Activities

As stated earlier, here we refer to Critical Path Activities as those with a Total Float of 0 (zero) or less than the time between reporting periods. 

The challenge here is to ensure all critical path activities are progressed to the plan in order to avoid delays.

If a project’s reporting period is monthly, you will win few friends among project stakeholders by only monitoring progress of critical path activities once per month. 

Such activities should be more rigorously monitored in order to ensure negative deviations are identified early and the underlying causes corrected straight away.  Measuring physical progress fortnightly, or even daily, is justified in these circumstances, but it’s important to use a simple visual progress monitoring tool which can be easily understood by all who are involved with the task’s completion, and which clearly shows whether progress performance is as required. 

REMEMBER, whether activity detail exists within the software scheduling system or outside of it - someone somewhere should have the detail covered adequately!


It’s a good idea to keep a track of the quantity of CriticalPath Activities within your project.  The more activities thatbecome critical path activities as your project progresses, the moreeffort is needed to manage the workflows and the higher the risk of aworkflow eventually delaying overall completion of the project. Time delays usually equal cost over runs.

The rate of increase in the number of Critical Path Activities is one good measure of a project’s health.

The use of Progress Indicator Graphs is a good Low Tech, High Touch tool to use in such circumstances, detail of which can be found in the Project Control area of this website.

For more on the practical application of Critical Path Analysis as well as how to push the boundaries with a project’s critical path without introducing unnecessary risk, get in touch with us via the Contact Us, for an initial discussion at no cost or further obligation.

Please also get in touch if you are interested in how to better ensure control of your project’s critical path activities and ensure you successfully deliver your project.

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