Develop Your Project Schedule

One of the triple constraints of project management is time. Management, project team members, other project managers, customers, and other stakeholders are going to want to know how long your project will take to complete. The scope of the project, the amount of available resources, and the abilities of those resources all impact how long the project will actually last.

One of the biggest impacts on the project schedule – one that I believe is often overlooked – is the capability and competencies of the project team members. If your project team has very limited experience with the technology your project centers on you’ll be plagued by inaccurate time estimates, delays, and frustrations by the project team members and your project stakeholders.

Here’s a fundamental project management tip: if your project team doesn’t know how to do the work they need to be trained. Sounds simple and logical, yes? But you may be amazed at how often organizations ignore this basic principle for a variety of reasons: monies for training, time in the classroom, or fear that the project team member may learn something new and then leave the organization to work for someone else. Which begs the question – would you rather train a project team member and maybe lose them or not train a project team member and keep them?

Once you have created the activity list you and the project team can work together to create a project network diagram as seen in Figure 5. A project network diagram is a visual representation of the order of the activities needed in order to complete the project. Most project network diagrams use a technique called the precedence diagramming method – which is just a way to say that a project activity has predecessors and successors. A predecessor is an activity that must be completed before a successor activity can begin. In Figure 5, activity D is both a predecessor and a successor because it precedes activity E and succeeds activity C.

Figure 1: Project network diagrams visualize predecessors and successors.

Real World Note: If you use Microsoft Project to assist your project management activities you’ve been using the precedence diagramming method. The approach in Figure 5 and in Microsoft Project is also called activity-on-the-node (AON) because, well, the activities are on the node. An antiquated approach has the activities-on-the-arrows, but its rules limit the structure of the network diagram so it’s not used that often any more.

A benefit of using the project network diagram is that you can identify the critical path. The critical path is the one path in the network diagram that cannot be delayed or the project will be late. You can find the critical path by using project management software, such as Primavera or Microsoft Project. You can manually find the critical path, if you really want to, by identifying all of the paths in the project network diagram and then adding up the duration of each node used in that path. In Figure 6 the longest path to completion is ACFJK as the sum of these activities will take 21 days.

Figure 2: The critical path is the longest path to project completion.

This tells us several things:

1. The earliest this project can be completed is within 21 days.
   
2. The longest this project will take to complete is 21 days – or else the project is late.
   
3. Activities A, C, F, J, and K cannot be delayed at all or else the project will be late.
   
4. All of the activities which are not on the critical path may be able to be delayed without affecting the project’s end date.
   

The idea of allowing some of the activities to be delayed, or rather taking advantage of delaying non-critical path activities is called float – sometimes also called slack. Float is the opportunity to delay an activity without delaying the project end date. There’s a tricky formula to manually calculate float – that I’m not going into here – any project management software worth a nickel will calculate float for you. Trust me, you don’t want to do this activity manually, if any relationship changes the float may change as well.

Real World Note: While I’m sparing you the headache of calculating float you’ll need to know how to manually do float for your PMP, CAPM, and Project+ certification. If you’re pursuing one of these certifications I strongly recommend one of the five books I’ve written on project management in which I gladly explain how to manually calculate float. I have books specific to the PMP, CAPM, and the Project+ certification. You can also watch a free video on finding float right here.