Using a Gantt Chart to manage a project schedule
Note: The original Gantt chart developed by Henry Gantt in 1910 was not the same as the one we use today; it actually showed resources against time (but that’s a topic for another blog post). Today we are interested in how we can use a modern day Gantt chart to plan and control our projects.
There are many different techniques and tools that a project manager can use to control a project schedule on a day-to-day basis and for managing dependencies, change and risks. However, it is important to distinguish between techniques and tools so you understand the technique before using a software tool. The ability to use a software tool is not necessarily an indication of a detailed knowledge of, or effective use of, the technique behind it.
What is a Gantt Chart?
The underlying concept of a Gantt chart is to map out which tasks can be done in parallel and which need to be done sequentially. If we combine this with the project resources we can explore the trade-off between the scope (doing more or less work), cost (using more or less resources) and the time scales for the project. By adding more resources or reducing the scope the project manager can see the effect on the end date.
A Gantt chart displays information visually as a type of bar chart in a clear and easy-to-understand way and is used for the following activities:
- Establish the initial project schedule
- Allocate resources
- Monitor and report progress
- Control and communicate the schedule
- Display milestones
- Identify and report problems
To create a chart you need to know all of the individual tasks required to complete the project, an estimate of how long each task will take and which tasks are dependent on others. The very process of pulling this information together helps a project manager focus on the essential parts of the project and begin to establish a realistic timeframe for completion.
Find out more about gantt charts with APM: What is a Gantt chart?
Disadvantages of a Gantt Chart
But Gantt charts are not perfect and all too often they become overly complex with too many dependencies and activities. This is a trap many new project managers fall into when they start using planning tools. It is much better to produce a clear and simple plan that shows the main work packages in summary, than a plan with so much detail the overall impression of project progress is lost. Let the work package manager put together the day-to-day detail of the activities within a work package, while the project schedule concentrates on the interfaces between project teams.
Neither are they good at showing the relative priorities of individual tasks and the resources expended on a task. Tasks are prioritised on the amount of float not their importance to the project. For example, they can clearly show the elapsed time of a task but cannot so easily communicate how many people may be needed to complete that task. So if not backed up by other data they can give a misleading impression to stakeholders. This is where using additional techniques such as a precedence diagram (sometimes called a PERT chart), for instance, becomes useful
A precedence diagram is another powerful project management technique which is particularly useful for identifying complex inter-dependencies and showing relative priorities of activities and, hence, highlighting the tasks most critical to project success.
Other blogs in this series:
- Project management – an introduction
- Project management processes and phases
- Business requirements and project managers
- People and behaviours in project management
This is a project management fundamentals blog written and sponsored by Parallel Project Training. For more about our project management training courses visit our website or visit Paul Naybour on Google+.
Paul Naybour is the Business Development Director for Parallel Project Training. He is a well-known speaker in the APM Branch Network, a Project Management Trainer and Consultant. He is also one of the voices behind the popular series of APM PMQ podcasts.
6 comments
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Sorry for the delay replying to your comments. The past few months have been peak time for us.Patrick you are of course correct that the chart drawn by Henry Gantt was not the same as what we recognise as a Gantt chart today. I admire your determination in re-educating us all on this fact. We did acknowledge this in the opening paragraph. Interesting I checked the definition in the APM and PMI Bodies of Knowledge and they both define Gantt chart as the project schedule. I am happy the support you campaign to get this corrected, but for now I am going to stick with the industry standard definitions. Richard planning is much neglected, compared to say contract law or cost planning, which have their own professional recognition. It is interesting why PM dont see it as important. I quite like planning in all its forms (corporate, business and project), but I have discovered that this is generally not the case. I think it is because most people see it as a waste of time because the plans are out of date before the ink is dry. For me its not the plan that matters but the thought that goes into it. I have often thought that a planning academy with certification might be of benefit, but it never seems to get off the ground, yet.
It would help the profession enormously if people writing about a subject at least attempted to use the proper names for the tools and techniques being discussed.First, Henry Gantt had absolutely nothing to do with project management, and 90% of his charts were filled in post the event (ie, at the end of the day recording what happened on that day) and the few that were predictive, such as the load chart considered the use of a machine in a machine shop. Bar Charts were very much a UK and European invention dating from the mid 18th century and the work of Playfair and Priestly, with their roots going back to the Ancient Greeks. Bar Charts seem to have been fully developed in Europe (and presumably the UK) by the end of the 19th Century. The 1910 Schrch Bar Chart referenced in my 'History of Schduling' paper would be better then many developed on modern projects.Second, Bar Charts do not show any form of logic (and neither did any of Gantts charts). Logic can be inferred from positions of the bars, but no more. The first attempt to include logical constraints in a Bar Chart was Karol Adamieckis Harmonogram (or Harmonygraph) of 1896.Bar Charts including links are called a range of names, time scaled network and logic linked barcharts being the most relevant depending on the overall layout of the diagram. The fact Microsoft chose to call a precedence network diagram a PERT Chart and a Bar Chart a Gantt Chart merely serves to demonstrate the lack of knowledge of the people working for Microsoft in the 1980s.There are several researched papers available on my website that define the development of scheduling, project management and Gantts real contribution to modern management (including copies of all of Gantts books) at http://www.mosaicprojects.com.au/PM-History.html The thing I find hardest to understand is why English people refuse to accept the credit for an English / Scottish development and want to defer to American propaganda!
As Paul points out the Gantt chart is not without its disadvantages but can be a useful technique/tool for certain projects. As always the techniques and tools a project manager uses are dependent on the type of project and also what is commonly used in his/her organisation.In my experience the project planner is the project manager - if there is a separate role for the planner then surely that is simply an admin role?
Michelle, I totally disagree with your comments. The Project Manager should be too involved with managing their project and leave the planning to the planner. Many PM's haven’t a clue how scheduling software works never mind how to properly plan projects complex or not. The planner now days is seen as an essential member of the project team. The 'PM' can do everything is the cause of many failing projects, having a good planner and a good plan is at the heart of any successful project.
An interesting view.You can in tools such a Primavera focus upon resources. Also other planning methodologies such as critical chain can be deployed. The plan should tie back to the scope of work and estimate, because the plan communicates both, and is a vehicle for the PM to communicate his/her project.Overall I do finding Project Planning is often not seen as that important, and indeed I find many project managers, don't really understand the basics of plans and planning - scary stuff! Maybe its time the APM widen their focus to be more inclusive of other Project roles, such as Project Planners, who often feel to be overlooked by the profession, or just seen as admin support / report producers.Personally its little surprise why there is a shortage of Project Planners, because of the way its viewed by the profession.Indeed within the user profile on this very site, "Project Planner, Project Controller, Planning Engineer", are not even listed as job descriptions!!!!
I always had an image of Gantt chart sucks in project management. But after reading this article my way of thinking has changed. Project managers can free Gantt chart template - http://www.techno-pm.com/2016/06/gantt-chart-excel-template-free-download.html for project management.