One of the less discussed features in a good project managers arsenal is the ‘Critical Path’ of a Project. That’s probably because we don’t tend to spend too much time calculating the critical path by hand but rather we consult it as a part of the Gantt Chart in our Project Management Software. It doesn’t make it any less important though. 

With the nice overhaul of our ProWorkflow Gantt Chart (including a Critical Path feature) coming up in a few weeks, we thought it would be an interesting exercise to look at the thinking path behind the concept. 

If anything, it makes you appreciate technology a bit more. 

First things first

To work out the critical path, you start the project as you always would. 

The steps we mention feel a bit superfluous, but rest assured; they’re not. They are vital in getting the critical path right. What’s more, any painful errors in the critical path often boil down to taking short-cuts in these steps.

What is the critical path? 

As you probably already know, the critical path tells you the longest time it will take to complete the entire project. This is important information because any delay on that path delays the entire project. In other words, the critical path tells you what the minimum time is you need to finish a project as well as which tasks have no wiggle room and which ones do. 

In the real world, the critical path can also be a very valuable tool for when you become time strapped: you can shorten the entire project by shortening the critical path. For instance, you customer might need you to finish a project by a certain date. After you’ve worked your way through all the above steps, you realize that you’re a couple of days short to meet the customer’s request. 

We’ll explain later on how you can do that. First let’s see what the importance is of a task without wiggle room to the projects finish date. 

Total Float and Critical Tasks

Tasks are critical if they don’t have any room for delays. Any delay in that critical task activity also delays the finish date. The amount of wiggle room you have in a task is called slack or float in project management. 

Total float (or float for short) is the time an activity can move earlier or later without affecting the project finish date. 

This will give you a clear picture of a project’s timeframe and if it will meet its deadline. If it doesn’t you can make adjustments. 

Total float is so important that it even has a formula: 

Total float = late finish – early finish 

There are guidelines on how to calculate the late finish and early finish called backward and forward pass, but we’ll leave those for another time.  What is important to know is that if an activity’s total float is 0, it’s on the critical path.  If an activity’s total float is more than 0, the activity can delay by that amount without affecting the finish date. These tasks are called floating tasks. 

All of that is not just a useless waste of time. On the contrary, having this info, can help you consider some smart moves. If a task has a total float of more than 0 and therefore not on the critical path, it can give you the freedom to move resources somewhere else where they may be more crucial. Say moving resources and the money saving bells should be ringing. 

But, if your project is strapped for time and at risk of overrunning the deadline, the total float information can be used to adjust the schedule. 

How do you shorten the critical path? 

Because shortening the duration of a project typically also reduces its cost, shortening the critical path is often your primary goal as a project manager. 

There are two ways in which you can shorten the critical path. 

·      You can shorten the duration of critical tasks themselves

·      You can overlap critical tasks by scheduling them simultaneously.

Most of the time, you’ll do a bit of both and your Gantt Chart as well as the critical path should help you figure out the best way to do it. 

The bottom line

What should be clear by now, is that the critical path of a project is a precious tool to optimise the time frame for your project, and in doing so also minimize cost and make the most of your resources. 

The good news is that you don’t have to perform the calculations we explained above. Project management programs take care of this for you. In a few weeks’ time, you will be able to simply go to the ProWorkflow Gantt Chart and get it to highlight the critical path for you.