Critical Path Tasks


People who manage projects, either full-time as a project manager or part-time as a department manager, know that the critical path is the longest path of tasks in a project. It determines the duration of the entire project. They also know which of the tasks in the project are Critical Path Tasks. But knowing the definition and actually using it to finish your projects earlier are two entirely different things.

How to Manage Critical Path Tasks

When you actively manage critical path tasks you can do these important things:
  • find ways to shorten the duration of the project without increasing costs or risks
  • quickly identify variances you don’t have to do anything about
  • spot places where you can decrease the assigned resources and make better use of them elsewhere.

To actively manage the critical path tasks, you need to identify which tasks in your project are on the critical path. You also need to know how much slack (float) the no-critical tasks have.  The slack number tells you how many days the task can slip before it becomes a critical path task and increases the project’s duration. You can shift resources off tasks with significant slack and move them onto critical path tasks. That should shorten the duration of the project without adding costs or risks. This fine tuning or optimizing of the project plan takes minutes and can yield important decreases in the project duration.

Identifying the plan variances you have to do something about is as valuable as identifying variances where you don’t have to do anything. Obviously a variance or slippage on a critical path task is going to ripple all the way through the project and affect your finish date. However, if you have a variance of 3 days on a task that has 13 days of slack , you don’t need to be terribly concerned. You want to make sure that the 3 day variance is not symptomatic of a larger problem. But if, for example, it is a minor error in the estimate then you don’t need to take time to solve the problem because you still have 10 days of slack left on that task. This allows you to use under-estimating as a teaching tool with the team member when it occurs on a non-critical path task.

Additionally, you can look at tasks with slack as a pool of available resources. Let’s look at a simple example. If we have a task with 21 days of slack and three team members assigned to it, you might be able to reduce the staffing by one or two team members. If their skill sets are compatible, you can add those people to a critical path task during the weeks when they were scheduled to work on the task with all the slack. Obviously, this kind of fine-tuning depends on staff compatibility. You’re not going to transfer two engineers to a task that requires a graphic artist. But moving available resources gives you the ability to shorten the duration without increasing the project’s risks or costs.

Critical Path Tasks – A Real Example

As an IT project manager in the planning phase of a system upgrade project, I had been trying to write a perfect plan for managing the critical path activities. There was a task in the critical path called “Final Upgrading System on the Live Server.” The duration of this task was two days and users could not work during that task execution. Project Schedule & Software Main Page

I spoke to the upgrading implementer who said during those two days we would enable the backup system on the backup server and have it ready for users to enter their daily work. However, he added, users must redo their work transactions on the live production system once it is ready. Redoing transactions might require users to work more hours to enter the backlog. I was thinking about utilizing the weekend to finalize this task. I contacted the HR manager, explained the issue and asked for a solution. The HR manager suggested paying overtime for the implementers. I said overtime was a bad idea for managing projects because it increases the budget. The PM methodology does not recommend it. But I suggested talking with implementers and asking them to work an additional two days, then letting them add two days to a future weekend so that they could go for long weekend vacation. We would  count the business hours they work during the weekend. The HR manger thought it was a good idea. I got approval & commitment from their direct manager, the HR Manager, and the functional Department Manager. I documented all these commitments.

Consequently, the project plan was executed successfully within its planned budget, duration, scope and risk. Users did not redo their data entry work load and implementers went for a long weekend vacation. The case was uploaded as a project lesson learned.

Learn how to use the critical path tool to quickly identify problems, efficiently use resources and cut the project duration in our online project management basics courses. You work privately with a expert project manager via live online video conferences, phone calls and e-mails. You control the course schedule and pace and have as many phone calls and live video conferences with your instructor as you wish. Take a look at the course in your specialty.

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Author: Dick Billows, PMP

Dick has more than 25 years of project and program management experience throughout the US and overseas. Dick was a partner in the 4th largest professional firm and a VP in a Fortune 200 company. He trained and developed 100's of project managers using his methodology. Dick is the author of 14 books, over 300 articles and director/producer of 90 short project management training videos. He and a team of 25 project managers work with client companies & students across the US and in Europe, South America, Asia and the Middle East. They have assisted over 300 organizations in improving their project performance. Books by Dick Billows, PMP are on