Gantt charts are useful tools for analysing, planning and controlling complex multi-stage projects. It very helpful for a manager for his project management.
Gantt charts can:
- Assist in identifying the tasks and sub-tasks to be undertaken
- Help you lay out the tasks that need to be completed
- Assist in scheduling when these tasks will be carried out and in what order
- Assist in planning resources needed to complete the project
- Assist in working out the critical path for a project where it needs to be completed by a particular date
When a complex or multi-task project is under way, Gantt charts assist in monitoring whether the project is on schedule, or not. If not, the Gantt chart allows you to easily identify what actions need to be taken in order to put the project back onto schedule.
An essential concept behind project planning is that some activities depend upon other activities being completed first. For example, it is not a good idea to start building the walls in an office block before you have laid the foundations; neither is it a good idea to put the cake mix into the tin without greasing the tin first.
These are dependent activities which need to be completed in a sequence, with each stage being more-or-less completed before the next stage can begin. We can call such dependent activities ‘sequential’.
Non-sequential activities are not dependent on the completion of any other tasks. These activities may be done at any time before or after a particular stage in the project is reached. These activities are called are non-dependent or “parallel” tasks.
To create a Gantt chart:
Step 1. List all Activities/Tasks in the Plan
For each task, show the earliest possible start date, how long you estimate the length of time it should take, and whether it is parallel or sequential. If tasks are sequential, show which stages they depend on.
Head up a sheet of graph paper (using pencil and a ruler) with the days, weeks or months through to task completion on the top x-axis. The y-axis can be used to itemise each task in its order. You may want to use a spreadsheet for this instead of graph paper if you prefer.
Step 2. Plot the Tasks onto the Plan
Next list the tasks in the first column on the left hand side of the page, the y-axis. To draw up a rough first draft of the Gantt chart; plot each task on the plan, showing it starting on the earliest possible date. Draw each task as a horizontal bar, with the length of the bar being the length of time you estimate the task will take. Above each task bar, mark the estimated time taken to complete the task. At this stage there is no need to include scheduling – all you are doing is setting up the first draft.
Step 3. Schedule the Tasks/Activities
Now on a fresh sheet redraw the Gantt chart to schedule actions and tasks. Schedule these in such a way that sequential actions are carried out in the desired sequence e.g. dig holes, lay foundations, begin construction. Ensure that these dependent activities do not start until the activities they depend on have been fully completed.
Where possible, schedule parallel tasks so that they do not interfere with sequential actions on the critical path. While scheduling, ensure that you make best use of the time and resources you have available. Do not over-commit resources and allow some time in the schedule for holdups, overruns, quality rejections, failures in delivery, etc.
Once the Gantt chart is drawn, you can see how long will it take to complete your project. The key steps to be carried out to ensure successful completion of the project should be clearly visible.
In practice professional project managers use sophisticated software like Microsoft Project or Microsoft Excel to create Gantt charts. Not only do these packages make the drawing of Gantt charts easier, they also make subsequent modification of plans easier and provide facilities for monitoring progress against plans. Tables and spreadsheets can also be used to create simple and easy to change charts without Microsoft Project. Spreadsheets with coloured bars are most useful for the simplest projects.