10.26 Gantt Charts

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The Gantt chart is a matrix-formatted document that lists on the vertical axis all of the tasks to be performed. Each row contains a single task identification, which usually consists of a number and name. The horizontal axis is headed by columns indicating estimated task duration, the skill level required to perform the task, and the name of the person assigned to the task, followed by one column for each period in the project’s duration. Each period may be expressed in hours, days, weeks, months, or other time units. The graphics portion of the Gantt chart consists of a horizontal bar for each task connecting the period start and period end columns. Each bar is drawn on a separate line, and the name of each person assigned to the task is also printed out on a separate line, often just beside or below the bar. In many cases when this type of project plan is used, a blank row is left between tasks. When the project is underway, this row is used to indicate progress with a second bar, which starts in the period column when the task is actually started and continues until the task is actually completed. Comparison between estimated start and end dates and actual start and end dates should indicate project status on a task-by-task basis.

Variations of this method include a lower chart, which shows personnel allocations on a by-name basis. For this section, the vertical axis contains the number of people assigned to the project, and the columns indicating task duration are left blank, as is the column indicating the resource assigned. The graphics portion consists of the same bar notation as in the upper chart, but it indicates that the designated person is working on a task. The value of this lower chart becomes clear when it shows slack time for project resources. Slack time is time when resources are not actually working on a project.

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