Critical Path Method forms the backbone of any decent scheduling software. As a Microsoft Gold Partner, we’d obviously advocate Microsoft Project, although other tools are available.

What is a Critical Path Method?

A quick summary of a quality schedule involves a logical hierarchical structure

  • Tasks are linked to show their dependencies through Finish to Start, Start to Start, Finish to Finish and even the peculiar Start to Finish links
  • Links might even make use of lag, and time within the link itself
  • The critical path is then deduced, showing us the sequence of tasks that determine the end date of a schedule
  • Tasks on the critical path have zero floats
  • Any delay to these tasks directly impacts the end date

A good Project Manager should therefore know that tasks on the critical path are, as the name suggests, critical to achieving the planned end date. I have been involved in large scale projects in the past where we have focused on tasks with less than 5 days float as a priority. In these large capital projects, there have been two or three dedicated Scheduling Engineers, building, refining, updating and analysing the +1,000 task schedules. Did critical path analysis help on such a project? Of course, it did! If this situation is you, then well done, no need to read further.

The reality for most people managing projects is that they don’t have access to a dedicated Scheduling Engineer/Planner. They must build and manage the schedule themselves. There are lots of successful Project Managers who don’t adhere to best practice scheduling. They have not even been trained in how to build a schedule or use MS Project.  It happens a lot.

We, therefore, see lots of schedules of lower quality. They are more likely to be used as a communications tool than a mechanism to manage tasks. Schedule in Excel? Plan on a page? It’s a communications tool, not a planning tool. These Project Managers and project teams are not reviewing and updating the schedule on a weekly basis, recalculating and analysing the critical path.

Critical Path Analysis

Critical Path Analysis is required for a high-quality schedule. Many projects don’t have this and are likely to suffer as a result. Equally many projects perhaps don’t need this level of sophistication or have tasks with such “hard” dependencies. A marketing plan does need the same schedule rigour as a hospital construction project. The latest project management software solutions are a testament to this. Many of the lighter tools do not provide critical path capability, but rather focus on collaboration and task assignments.

At this lighter end of project management, what can we learn and incorporate from critical path analysis techniques? A project is a journey. There are key stops on the way. These are our milestones. Key events, decision points, meetings, and approvals tell the story of the project. As a minimum let’s define this path and agree on target dates for our milestones. We can then break the project down into these smaller “work packages” and consider the tasks required to achieve each milestone.

Critical path technique

  • The post-it note technique enables us to get the task information out of our heads. Think about which tasks are required to achieve each milestone, write them onto a post-it note, and then move them around on the wall/flip chart/whiteboard in order to visualise the high-level sequence.
  • Consider elapsed time for each task. How long will it take based on what we know?
  • Treat the milestone as an Anchor Point.
  • This date is fixed (as much as any date can be) so working backwards calculate dates for each task based on the assumed elapsed time.
  • Review these dates. Are they realistic or have we just planned backwards into 3 weeks ago?
  • It’s likely there’s more than one route or path through this task sequence. Which path is the trickiest? Which path holds the most risk? Which path (and therefore tasks) is most likely going to impact our proposed milestone Anchor point date? This is our “critical path”. We don’t need to formally calculate it; we can just see which route through the project is most likely to cause a delay.  The Project Manager and project team can keep a focus on these tasks, monitoring and managing this work more closely.

Critical path analysis required a detailed logically linked schedule. Critical path awareness doesn’t but shines a similar light onto those tasks that are more likely to determine the end date. Every good Project Manager can keep critical path awareness in the forefront of their thoughts, even if they just have a Plan on a Page.

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Monthly Newsletter

By: Vince Hines

Vince Hines
Managing Director BSc, MAPM, MACostE, MIoD, MCTS, MCITP, MCT PMO-CP, PRINCE2 & P3O

Published: 30 May 2022

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