Why Managing Critical Path is Critical!


Practicing PMs should review their schedules on a regular basis to gauge if their project is on track or need some active management to correct any schedule deviation. If there is any deviation, there are a number of project management techniques that can be used to bring it back on schedule. This is where critical path method technique comes for the rescue!

The Project Management Body of Knowledge (PMBOK) defines the critical path method or more commonly termed critical path as “the sequence of schedule activities that determines the duration of the project.” Project managers can also apply the critical path methodology technique to “determine the amount of float on various logical network paths in the project schedule network to determine the minimum total project duration.”

Critical path method is a modeling technique and is commonly used with all forms of projects, including construction, aerospace and defense, software development, research projects, product development, engineering, among others. Any project with interdependent activities can apply this method of mathematical analysis

To identify a critical task is to construct a model of the project including the following:

  • A work breakdown structure
  • Estimating the time duration required for each activity
  • And dependencies between the activities

What is a Critical Task?

A task in your project schedule becomes critical if:

  • It has no slack
  • It has a Must Start On or Must Finish On date constraint.
  • It has an As Late As Possible constraint in a project scheduled from a start date.
  • It has an As Soon As Possible constraint in a project scheduled from a finish date.
  • It has a finish date that is the same as or beyond its deadline date.

Note that a task stops being critical when it’s marked as completed, because it then can no longer affect the completion of successor tasks or the project finish date

What is Fast-Tracking?

Fast tracking means that activities that are normally done in sequence are done partially in parallel by adjusting the resource availability upfront. For instance instead of waiting for entire design of your IT project to be completed, you consider starting a chunk of development/coding work in parallel. Fast-tracking at times involves risk that could lead to increased cost and some rework later. For example if the design changes at a later stage, development work done in parallel to design may lead to complete or major re-work! So Project Managers have to evaluate based on unique situation of their projects after careful consideration of trade off.

If you’re willing and able to spend more to accelerate the schedule, fast-tracking may be a viable option for you.

Crashing the project schedule

“Crashing” the schedule means to throw additional resources to the critical path without necessarily getting the highest level of efficiency.

For instance, let’s say one person was working on a ten-day activity on the critical path. If you were really hard pressed to shorten this timeframe, you might add a second resource to this activity. Additional resources may come from within the project team, or they may be loaned temporarily from outside the team so crashing usually always leads to some additional incremental cost to the project. Additionally you may also like to evaluate following techniques depending on your project situation;

  • Schedule overtime.
  • Shorten the duration or work on a task on the critical path.
  • Change a task constraint to allow for more scheduling flexibility.
  • Break a critical task into smaller tasks that can be worked on simultaneously by different resources.
  • Revise task dependencies to allow more scheduling flexibility.

In conclusion, both Fast-Tracking and Crashing should be applied only on Critical Tasks on your project schedule, as if they are applied on non-critical tasks they won’t be much useful. Also note that Fast-Tracking is always considered first line of defense mostly because it does not increase your project cost.

Shyam Verma, PMP, ITIL
IT Project & Program Delivery Professional
LinkedIn:spverma. Twitter: Shammy11
This article is also available on blog site http://pmpower.wordpress.com
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