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Figure 8-22: Gantt chart showing progress of project on Day 22.
Figure 8-22 pictures the project as it might appear or, its twenty-second day. Actual progress is shown as a heavy line added just below the scheduled progress line. Activity a started and finished on time, while b started on time but was completed one day late. Activity c was begun two days late and finished three days late, which delayed the start of h. (In this case, the predecessor relationship of c to h is clear.) Activity d is under way and was started on time. Activities e, f, and g were all started one day late. Even with some activities starting late, nothing has happened to delay the actual critical path. While it is not clear from the Gantt chart, the network (Figure 8-15) shows that the delay in b means that the b-g-i path has gone critical.
This example illustrates both the strength and weakness of the Gantt chart. Its major strength is that it is easy to read. All popular project management software will prepare Gantt charts, and most have some options available for customization, Gantt charts are often mounted on the wall of the project office and updated frequently. Anyone interested in the project can see the state of progress easily, even if the interested party knows little about the actual nature of the work being done. The weakness of the Gantt chart is simply that one needs the PERT/CPM network (or the WBS) to interpret what appears on the Gantt chart beyond a cursory level—or to plan how to compensate for lateness.
Another advantage is the ease of construction of the chart. In our example, we converted the PERT/CPM network in Figure 8-15 to a Gantt chart by modifying the network as in Figure 8-20. In practice, this intermediate stage is not necessary, and one can easily go from network to chart in a single step. On balance, ease of construction and ease of use have made the Gantt chart the most popular method for displaying a project schedule |25). Nonetheless, a PERT/CPM network is still needed for the PM to exercise control over the schedule.
In many ways, the Gantt chart is similar to the project master schedule described in Chapter 5. Both are types of bar charts and are used similarly. The major difference is that the Gantt chart is intended to monitor the detailed progress of work, whereas the master schedule contains only major tasks and is oriented toward overall project management rather than precise control of the detailed aspects of the project.
While PERT/CPM and Gantt charts are both scheduling techniques, they are not merely different ways of achieving the same ends; they are complementary rather than competitive. The budget can be directly related to the Gantt chart, as shown in Figure 8-23.
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What you need to know about… Project Management Made Easy! Project management consists of more than just a large building project and can encompass small projects as well. No matter what the size of your project, you need to have some sort of project management. How you manage your project has everything to do with its outcome.