We now move to the second of the project management tools discussed in this resource, the Gantt Chart.
It's a funny name but one that sticks with you. Like a lot of things, it was named after the person that first invented it - Henry Gantt. Read the following for a bit of history on Henry Gantt and the Gantt chart:
Henry Laurence Gantt (1861-1919) was a mechanical engineer, management consultant and industry advisor. Henry Laurence Gantt developed Gantt charts in the second decade of the 20th century. Gantt charts were used as a visual tool to show scheduled and actual progress of projects. Accepted as a commonplace project management tool today, it was an innovation of world-wide importance in the 1920s. Gantt charts were used on large construction projects like the Hoover Dam started in 1931 and the interstate highway network started in 1956 (Source: http://www.ganttcharts.com/history.html)
But why bother?
A Gantt Chart is:
- A useful tool for planning and scheduling projects
- A tool that enables you to assess how long a project will take
- A tool that helps manage dependencies between tasks
- A tool that helps you monitor progress once the project is underway
- A modeling tool to help you get your project back on schedule
(based on 'Gantt Charts' online at: http://www.ganttcharts.com/index.html)
For further reading on Gantt charts check the summary page.
Complete Activity 3: Use of Gantt charts
How to Produce a Gantt Chart
Before you produce a Gantt chart, you need:
- A detailed list of tasks (from your Work Breakdown Structure)
- The start and finish dates of each task
- Any constraints on these tasks. A constraint
is a requirement for when a task must start or finish. The following are
examples of constraints (note: this information is taken from the MS Project
Help File and so is, to a certain degree, specific to that application.
It does however show the basic meaning of each type of constraint):
- As Late As Possible. With this flexible constraint, Microsoft Project schedules the latest possible start and finish dates for the task, given other scheduling parameters. This is the default constraint for new tasks for a project scheduled from the finish date.
- As Soon As Possible. With this flexible constraint, Microsoft Project schedules the earliest possible start and finish dates for the task, given other scheduling parameters. No additional date restrictions are put on the task. This is the default constraint for new tasks for a project scheduled from the start date.
- Finish No Earlier Than. This moderate constraint indicates the earliest possible date that this task can be completed. It cannot finish any time before the specified date.
- Finish No Later Than. This moderate constraint indicates the latest possible date that this task can be completed. It can be finished on or before the specified date.
- Must Finish On. This inflexible constraint indicates the exact date on which a task must finish. Other scheduling parameters such as task dependencies, lead or lag time, resource leveling, and delay become secondary to this requirement.
- Must Start On. This inflexible constraint indicates
the exact date on which a task must begin. Other scheduling parameters
such as task dependencies, lead or lag time, resource leveling, and
delay become secondary to this requirement.
- Start No Earlier Than. This moderate constraint indicates the earliest possible date that this task can begin. It cannot start any time before the specified date.
- Start No Later Than. This moderate constraint indicates
the latest possible date that this task can begin. It can start on
or before the specified date. See http://www.web-enable.com/member_.net/ms_project.pdf -
part 2 of lesson 1 (the section is entitled 'links') to read about
task constraints.
- Any relationships between the tasks. For example, you have to finish a web page before you can upload it. In that instance, the relationship is called a Start-Finish relationship. There are other types of relationships. You can read about these in the following table from the Microsoft Office Assistance Website (http://office.microsoft.com/assistance).
| Task dependency | Example | Description |
|---|---|---|
| Finish-to-start (FS) |  |
Task (B) cannot start until task (A) finishes. For example, if you have two tasks, "Construct fence" and "Paint fence," "Paint fence" can't start until "Construct fence" finishes. This is the most common type of dependency. |
| Start-to-start (SS) |  |
Task (B) cannot start until task (A) starts. For example, if you have two tasks, "Pour foundation" and "Level concrete," "Level concrete" can't begin until "Pour foundation" begins. |
| Finish-to-finish (FF) |  |
Task (B) cannot finish until task (A) finishes. For example, if you have two tasks, "Add wiring" and "Inspect electrical," "Inspect electrical" can't finish until "Add wiring" finishes. |
| Start-to-finish (SF) |  |
Task (B) cannot finish until task (A) starts. This dependency type can be used for just-in-time scheduling up to a milestone or the project finish date to minimize the risk of a task finishing late if its dependent tasks slip. If a related task needs to finish before the milestone or project finish date, but it doesn't matter exactly when and you don't want a late finish to affect the just-in-time task, you can create an SF dependency between the task you want scheduled just in time (the predecessor) and its related task (the successor). Then if you update progress on the successor task, it won't affect the scheduled dates of the predecessor task. |
Interpretation of a Gantt Chart
Before we go on to examine how to produce a Gantt chart, it is helpful to see some examples, and a little about how to interpret the chart.
Look at the following example (example 1), found on http://www.ganttcharts.com/Examples.html (if you want to see more examples, this is a great site!)
The beauty of the Gantt chart is its simplicity. The horizontal axis always represents the time. The vertical axis always represents the tasks. The horizontal bars show the duration of each task. The start and end of each bar (usually marked off with a special shape, in this case a circle) shows the start and end time/date of the task.
In this more complex example, you can see extra information on the chart.
Click this image to see a larger version of the graphic.
Notice that we can place tracking information on the chart by putting a line inside the task bar to indicate progress on a task. We can also put text next to the bars so that we can see who is assigned to the various tasks. We can also use lines between tasks to show task dependencies.
Now let's move on and discuss how to do it.
Manual Method for Producing a Gantt Chart
You could draw a Gantt chart if you wanted to. All you need is a pencil, ruler and some graph paper. You would construct your chart like the one in the diagram:
Click this image to see a larger version of the graphic.
Drawing it by hand is acceptable, but it becomes messy if you want to change it. This is the big advantage of using software to draw your chart.
Using MS Project
MS Project gives you a graphical interface to use in drawing Gantt charts. If you are able to get the MS Project software, you should try the following tutorial:
http://www.web-enable.com/member_.net/ms_project.pdf
Complete Activity 4: Creating a Gantt chart