Part of project management requires the determination of the critical path. So what is that?

We’ll take a simple example from the kitchen. This simple meal comprises grilled steak with vegetables and mash.

The cook can only do one thing at a time, the meal needs to be ready as quickly as possible and all three components of the meal are to be ready for serving at the same time (no hot tray here!).

The question is which is the sequence of the following processes which will determine the total time from start to finish.

The first thing we need to do is to determine the time for each process. Then we sort them out into paths such that the cook is not required to do two things at a time.

Then we find the path that has no slack. That is the critical path.

So, what is so special about the critical path?

When planning a project, one of the goals is to complete it as quickly and efficiently as possible. If you are trying to reduce the overall project time, there is no point in focussing on anything that is not on the critical path, as that will simply introduce more slack and not shorten the overall completion time.

So, let’s use a pressure cooker to shorten the potato boiling time. 

Notice that the critical path has shortened and there’s less slack in the centre path. Now let’s use a machine to mash the spuds.

Now we have slack in what was the critical path and the new critical path is that in the centre. Maybe there’s a machine that peels potatoes!