The mechanics of monitoring a project using the operations Gantt chart is illustrated in the following simplified example. You should assume that there are enough tasks on the critical path to justify calculating a risk factor. Note: the demonstration provided also works for larger projects.
Figure 12-1 represents a condensed basic Gantt chart for a product development project. For each task, the task's duration is entered. The people who will be working on the task are designated following the task bar; two designers will work on Task C and D; two machinists will work on Task G; and two assemblers will work on Task J. The relationship of the predecessor and successor is represented by one-line arrows that end with an arrowhead at the successor task. A risk factor, which has been calculated for the string of tasks, also is represented. Its duration is three days; it is entered at a fixed date; and it is not connected to any prior tasks by dependency arrows. The risk factor starts the day after the last task in the string (J) finishes. A zero duration inspection point is entered as Task J finishes. This point is connected to Task J by a dependency arrow. This baseline task is printed out, and it is saved as a baseline within software storage.
After the baseline has been saved, the basic Gantt chart is brought up on the Gantt chart display screen. As the tasks are finished, their actual durations are entered on this screen by the project manager. The software draws a thick black line within the task bar to represent task completion (see Figure 12-2). If the project manager enters percent completion for a task that is less than 100 percent, the black line only fills up that percent of the full length of the task bar.
As shown in the Figure 12-2, Tasks A and B finish on time. The critical path is A-B-D-H-I-J. Task C finishes half a day late, which will add cost to the project but not add time. Task C is not on the critical path. There is one day of slack between Tasks C and D. Task C has room to run over its estimate. Task D runs one day over. Task H depends on Task D; Task I depends on Task H; and Task J depends on Task I. When Task D overruns, Tasks H, I, and J will have to start one day late. (This should not be a big surprise.) Task workers for Tasks H and I and the team leader for Task J are on the project team. They know that their tasks are on the critical path and by the time the project gets to Task H, it is very likely that the A-B-D sequence of tasks may overrun. Nevertheless the project manager reminds all three to expect a late start as soon as he notes that Task D will overrun. Tasks E and F finish on time. Task G overruns by one day, which does not add to the project overrun because the task string E-F-G has three days of slack. Note how the project manager records this and prints out a partially completed Gantt chart (See Figure 12-2).
When Task H overruns one day (Figure 12-3), the project manager sees that two thirds of the risk factor is used up. With Microsoft Project 2002® the project manager has saved a base line and can print a tracking Gantt chart with lightly shaded bars and completed tasks with dark shaded bars.
Note the baseline Gantt chart shows its no risk duration point with a white diamond and the actual duration point (Inspection) with a black diamond. The black diamond travels above the risk bar, which does not move. It shows all the interested parties that when Task H is completed, the project has used up two days of the risk factor. This may seem easy to see here. But when there is a string of 20+ critical path tasks and numerous other non-critical path tasks, it is very good to be able to view the solid diamond with reference to the risk factor to see how much of the time buffer the project has used up.
The project manager cautions task leaders for Task I and J to look at their notes and use extra resources if they suspect that they might overrun. Task I finishes on time. Task J runs over a half-day (See Figure 12-4).
All but one-half day of the risk factor has been used up. The next string of tasks can start as planed on March 6, 2002.The risk factor worked very well. This is just what a project manager generally can expect.
This means of tracking a project's progress works for small projects and for very large projects. For very large, basic projects, having the critical path broken down into units of approximately 20 tasks and risk factors inserted at the breaks gives the project manager and the team better control of the project's time performance than having the risk factor at the end.
Using Microsoft Project 2002®, we indicate a task's startup by assigning five or 10 percent completion using software utilities. We do not enter further percent completion until the task is 100 percent complete. Percentage completion can be interpreted in different ways, which can result in a misleading display. We keep track of the progress of a task with notes written into our project diaries during a walkabout and teleconferencing. We regularly ask team leaders, "How many days of work are left?" and we use this information to show a task's percent completion. If the task is running over: it shows up on the operations Gantt chart when the days left are entered. It is the result when the task's completion date is pushed out by adding the days left to current date. Both of us are diligent about knowing how the task is progressing during a task's execution. Waiting until a task is completed to track and record the overrun limits is not what a project manager should do to help a task that is in trouble.
The operations Gantt chart is the planned project Gantt chart that is set up so that the task's actual duration can be entered as the work progresses. If a task runs over, the project manager enters the actual finish date for this task to the chart. The software then automatically moves all subsequent, dependent tasks further out in time. The task leaders of the successor tasks then are informed when the chart shows that their task will actually start later than scheduled.
The Gantt chart has been set up so that the risk factor task does not move. Displayed above the risk factor task is a diamond symbol (if Microsoft Project 2002® is used) that moves out in time as some tasks overrun. This diamond points down to the risk factor bar and represents at any specific time how much of the risk factor has been used up.
Because the downstream task leaders helped to develop the risk factor, they should not be surprised when their actual start dates are moved out somewhat farther than indicated on the basic Gantt chart. This also is easy to forget. The project manager, performing walk-about management; must remind the task leaders that their task's start-up could be delayed by as many days as indicated by the risk factor but never by more than the full amount of the risk factor. It is up to the project manager to keep the operations Gantt chart current. He or she must enter each task completion date the day that it happens. When one string of tasks ending in a risk factor is completed, the next task's start date is the day after the end date of the preceding risk factor. No one else is ever permitted to enter a completion date on the working Gantt chart. (Always put the chart in a password-protected file and specify a read-only access for everyone except the project manager.)
The project manager must find a good place to display the operations Gantt chart. A long hallway or a large conference room wall works best for large projects. An office wall works best for small projects. The chart must be changed every time a task is completed. The project's team leaders should have access to the operations Gantt chart on their PCs.