Continuing with our series on Project Management, let’s take a look at how we can significantly reduce the time required to complete a project and then begin looking at an alternative project management method.
As we’ve seen in CPM, task durations are inflated to protect against Murphy. What if we could significantly reduce these imbedded safety buffers and still provide the protection that we need? In our example from Figure 1, suppose we were able to reduce the estimated duration by 50 % and still protect against Murphy. In other words, if we could complete the tasks in 5 days instead of 10 days, wouldn’t this be a quantum leap in project completion time reduction?
Figure 3 depicts the 50% reduction in durations of each project. We have just reduced the time to complete these three projects from 30 days to 15 days, but can we do this and safely guard against the uncertainty introduced by Murphy? The answer is yes we can!
Earlier we demonstrated how by simply eliminating bad multi-tasking, significant gains can be made in project completion rates, but we still have to address the impact of the Student Syndrome and Parkinson’s Law. We know that both of these behaviors work to lengthen the time required to complete projects. Remember how excess safety is imbedded into traditional project management plans? Resources estimate task times and add in their own protection against disruptions caused primarily by Murphy. Knowing that this safety exists, resources then delay starting work on their tasks until the due date is close. Even if the resources don’t delay the task starts and finish early, these early finishes are not reported or passed on to the next resource. So how does CCPM deal with these two behaviors?
While CPM relies on individual task durations as well as scheduled start and completion dates, CCPM does not. The focus is no longer on finishing individual tasks on time, but rather starting and completing these tasks as soon as possible and this is a major difference. So how does this work? Like CPM, CCPM still gathers estimates on individual tasks and identifies its own version of the Critical Path. Unlike CPM, CCPM considers competing resources (i.e. the same resource has to work on different tasks) and makes them a part of the critical path. Let’s look at an example of how CPM and CCPM identifies the critical path.
CPM defines the critical path as the longest path of dependent tasks within a project. That is, tasks are dependent when the completion of one tasks isn’t possible until completion of a preceding task. The critical path is important because any delay on the critical path will delay the project correspondingly. Figure 4 is an example of a series of tasks which must be completed in a project with the critical path highlighted in grey. Traditional project management determines the critical path by looking at the task dependencies within the project. Task A2 can only be initiated after A1 is completed. Task B3 can only be performed after completion of B1 and B2. Task D1 can only be performed after completion of A2, B3 and C2. Using CPPM the critical path would have been identified as C1-C2-D1 and the project completion estimate would have been 29 days (i.e. 8d+12d+9d).
In addition to task dependencies there are also resource dependencies that CPM fails to recognize. What if, in our example, tasks A2 and B3 are performed by the same resource? Is the critical path different? In Figure 5 we see the new critical path that includes a provision for resource dependencies and as you can see the new critical path is A1-A2-B3-D1 or 5d+10d+10d+9d equals 34 days. So the minimum time to complete this project is now 34 days. In our opinion, this failure to consider resource dependencies is one of the key reasons why project completion rates are so terrible. The simple implication of incorrectly identifying the critical path, which we will now refer to as critical chain is that the project team will never be able to complete their project on time without heroic efforts, adding additional resources, overtime or a combination of all three. The practical implication of incorrectly identifying the real critical chain is that the focus will be on the wrong tasks.
In my next posting we’ll look at a better way to track a project’s status and how we can better observe all of the projects in our system.