The Gantt chart is a bar chart that illustrates the timing of project activities and their relationships. It displays activities on one chart against time to provide a simple representation of project scheduling. Gantt charts are useful for planning and overview but have limitations like difficulty updating and lack of cost/resource data. Alternatives for project planning include PERT, WBS, critical path and resource leveling.
2. The Purpose of a Gantt Chart:
âȘ To illustrate the relationship between project activities &
time.
âȘ To show the multiple project activities on one chart
âȘ To provide a simple & easy to understand representation of
project scheduling
3. Example of a
simple Gantt
Chart
ï§ You will see
that a Gantt
Chart is
basically a
Bar Chart.
Representin
g project
activities
against
time.
4. Creating a Gantt Chart:
There are 2 methods to creating a Gantt Chart (Maylor, 2005).
1. Forward Schedule: starting with the list of activities and a given start date (6th Sept
in previous example) follow them forwards in time until you hit given deadline.
2. Backward Schedule: look at the deadline, from that date work in the logical list of
activities.
Both of these methods allow you to ensure that all necessary activities can possibly be
completed within the given project time frame.
5. Steps to Creating a Gantt Chart:
1. Determine Project start date and deadline.
2. Gather all information surrounding the list of activities within a project â the Work
Breakdown Structure may be useful for this.
3. Determine how long each activity will take
4. Evaluate what activities are dependant on others
5. Create Graph shell including the timeline and list of activities.
6. Using either Forward Scheduling or Backward Scheduling, Begin to add bars
ensuring to include dependencies and the full duration for each activity.
6. Example:
Activity
Duration
Dependant On
1. Read Literature
21 days
N/A
2. Conduct Literature Review
14 days
1
3. Arrange Client Visits
7 days
N/A
4. Prepare Surveys
5 days
1 and 3
5. Conduct Surveys
14 days
4
6. Analyse Surveys
10 days
5
7. Write Up
30 days
1,2,3,4,5 and 6
Project Start Date = 1st September
Deadline = 20th Decemeber
7. Step 5 - From the previous
slide, steps 1-4 are already
complete. We now need
to create a âGraph Shellâ.
8. Step 6 â have a go at
using either
Forward Scheduling
or Backward
Scheduling to
populate the graph.
The Finished Product
9. The Advantages:
âȘ A useful tool for displaying time-based information within a project.
âȘ Very simple to create
âȘ They provide a useful overview of project activities, a good starting point for project
planning.
âȘ The charts are widely used and understood.
âȘ There exists several PC software packages that allow you to build Gantt Charts.
10. The Limitations:
âȘ The Gantt Chart does not explain the reasoning behind the chosen duration of each activity.
(Maylor, 2001)
âȘ The Gantt Chart is very difficult to update when changes to the project plan take place. This
makes it time consuming and results in long-term planning being very difficult.
(Goldratt, 1997)
âȘ Gantt Charts encourage a one-step approach to planning â this prevents flexibility in project
planning.
âȘ Modern day Gantt Charts, using PC software, can look very professional without actually
having meaning, preventing project teams from challenging their content. This can lead to
difficulties later in the project. (Maylor, 2001)
âȘ As Gantt Charts are difficult to update manually, they can often become obsolete.
âȘ The charts do not consider project costs or resources.
12. Program Evaluation and Review
Technique (PERT):
âȘ Also a very traditional project planning technique
âȘ PERT shows the list of activities within a project, their
duration and the relationship between them
âȘ PERT is a complex process however it can help to deliver a
well defined project plan.
14. Graphical Evaluation and Review
Technique (GERT):
âȘ Similar to PERT, however allows for looping, branching and the
display of multiple project results.
âȘ GERT can show possibilities if a section of a project were to fail.
âȘ Further GERT reading = Meredith and Mantel
15. Sources and Further Reading:
âȘ Meredith, J. and Mantel, S. (2010) Project Management: a managerial
approach, Asia: John Wiley and Sons
âȘ Maylor,H. (2003) Project Management, Essex: Pearson Education Limited,
3rd edn.
âȘ Field, M. and Keller, M. (1998), Project Management, Croatia: Thomson
Learning
âȘ Goldratt, E. (1997) The Critical Chain, New York: North River Press
âȘ Kerzner, H. (2009) Project Management, New Jersey: John Wiley & Sons,
10th edn.
âȘ Maylor, H (2001) Beyond the Gantt Chart, European Management Journal,
Vol 19, No.1, pp. 92-100
âȘ Wilson, J. (2003) Gantt Charts: a Centenary Appreciation, European Journal
of Operational Research, Volumne 149 pp. 430-437.
Hinweis der Redaktion
Reference: Maylor textbook 2005.
Well done!Obviously this is a very basic Gantt Chart. We will now take a look at why Gantt Charts are valuable within a project and why they are used. We will also consider the limitations to the Gantt Chart and introduce some alternative methods that are worth carrying out some background reading on.
For further reading on the advantages of the Gantt Chart, please refer to Maylor Chapter 5 or Field and Keller Chapter 3.3
Beyond the Gantt Chart, Maylor 2001, European Management Journal, Volume 19, pp. 92-100Goldratt, 1997, E.M. GoldrattThe Critical ChainNorth River Press, New York (1997)
Optional Task: read through the literature. Can you identify any other alternative approaches to scheduling?
PERT often displays the:O=Optimistic timeM=Most Likely timeP= Pessimistic Time
Please read Kerzner Chapter 12 for a detailed explanation of PERT.