Critical Path Calculations Are Flawed—Here’s How to Fix Them

The critical path on your project is probably not what you think it is, because critical path calculations are missing one key piece of information.

Refresher: Critical Path

The critical path is the chain of tasks that has no slack in your project schedule. It's the list of tasks, that if any one of them takes longer than planned, or starts later than planned, then the whole project is impacted. There's no slack to pick up.

As such, making sure that the tasks on the critical path go to plan, is, well, critical to the schedule of the project overall.

Knowing your critical path allows you to focus on the tasks that must go to plan.

But what if the critical path is wrong?

Of course, if you have your critical path wrong, the consequences for your project could be significant.

The bad news - it probably is wrong.

The maths is good, but data is missing

There's nothing wrong with the maths. You are calculating your path correctly, but we're missing one key data point - capacity.

When you consider each piece of work that needs to be done, which team needs to do it, and the capacity of that team, your path might change.

If there's a team in demand, other work may take priority over yours. While you can theoretically start the work now, realistically there might be a 3 month wait for capacity. When you factor that into the equation, your critical path might change.

Accounting for capacity

Making the change is easy. Simply add a new task, called wait, and set it to the correct wait time. The critical path calculation now doesn't need to change. If the wait state changes your critical path, you will see it.

The additional advantage is that the wait for capacity is transparent.

Without wait states correctly evidenced, critical path analyses have a decent likelihood of demonstrating the wrong path. When you make the change, you change your focus, you change your chance of success and you force a conversation about the impact of capacity and prioritisation.