Critical Path Review, Part 3

In this final installment, we will look at the concept of float, sometimes called slack, and its meaning in regard to Critical Path project management. Recall the diagram from Part 2:

By definition, the amount of float for any task on the Critical Path is zero. Therefore any increase in the length of any task increases the total project length by a like amount. In this case the total project length is 20 units, or for the sake of this discussion, let’s say 20 days. If we follow the path 1 – 3 – 6 – 8 we find that the total duration for that path is 12 days, so that path has total float equal to 6 days. But within that path, tasks B and J have zero float as they are on the Critical Path, therefore Task F has all of the 6 days of float, meaning the task can slide or take up to six days more without impacting the end date of the project.

What would happen if Task F slid 10 days instead? Now we would have a new Critical path (assuming everything else stayed the same) and it would look like this:

Now the total length of the project is 22 days. I’ll leave it to you to determine the float on the 1 – 3 – 5 – 6 -8 path.


About pmstrategies
As a Project Management Professional with over ten years of functional experience in a variety of projects for Fortune 500 companies and state agencies, I have a unique perspective on what works and doesn't work in the real world of project management. I am well versed in project methodologies, budgeting, compliance, approaches to strategic alignment and portfolio management, resource planning, staff management and contract management, and am an advanced user of Microsoft Project.

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