Definition: What is Gantt chart?
Definition of Gantt chart

It is, in its basic form, the Gantt chart is a visualisation of work data (the units of work in a project usually tasks or can be higher level as phases or program increments) over time. However it can be built on to also visualise the dependencies, milestones and even work effort. Like any data visualisation it can support better project decision making by stakeholders.

Why we think innovation when we think of Gantt charts

Every Project Manager or Project stakeholder will likely have one thing in common – the cookie cutter of Project processes and tools is unlikely to be a perfect fit given many projects (and the organisations that do them) are unique. As a result there is constant, iterative development of old ideas into new to tailor techniques to suit the context of the time. This is why most project managers or other project roles such as Scrum Masters will likely have a stash of tools and templates from previous experience that could be used again in similar circumstances.

Many of us will know that it is rare that what suited a project done last year will suit the one done now and so we all seek true innovation – a tool or technique that can be replicated easily and adopted on mass. Most importantly it will stand the test of time and the pure concept behind the innovation remains true no matter the context or instances. This is the case with the Gantt Chart which is never changed in structure but simply used again and again for different requirements.

Henry Laurence Gantt's (1861-1919) the inventor of the Gantt Chart

One can find multiple sources about Henry Gantt through simple Internet searches however the reference for this article is the British Library website.

I’ll leave you to read more about the man himself if you like your history however the point I would like to make is that Henry Gantt was a Project Manager who saw the need for standardisation of data (work, time, resource) and visualisation for ease of interpretation. There is an honourable concept behind this where the Gantt Chart was to be used as a form of assurance and early detection so that the ‘promises’ a Project Manager has made can be honoured, or if at risk, can allow early detection and advanced notice to customers.

From his idea and the development of a tool that would meet his needs, Henry Gantt came up with something that could be drawn on by countless projects and Project Managers for many years to come.

Uses for the Gantt Chart

One misconception of the Gantt Chart is that it is for Waterfall Projects only. While there may be simpler applications for visualisation of waterfall tasks and dependencies it is important to consider Gantt charts for Agile projects too. This is because the Gantt Chart can roll up any data attribute, if structured or mapped correctly to visualise actual progress (or capacity, or other data point) against planned, over a duration.

Here are a few principles that can help make best use of the Gantt Chart for your project:

  • Start with the Project Schedule or, if not feasible to do so, the roadmap that shows the committed deliverables over time. If the view you have of your project is too big or high level – use a Work Breakdown Structure to distil it down to smaller chunks of work.
  • Map the data points at the different reporting levels of your project whether that is a task within a Program Increment or the task hierarchy of a traditional project schedule.
  • Validate the dependencies across tasks and the plan and ensure you can identify which tasks could impact the project is altered (one way to do this is the Critical path method).
  • Validate the resource load / capacity per task or deliverable.
  • Define how you will measure progress against a value milestone such as a Release or a Go Live.
  • Recognise that a Gantt chart does have limitations so if you find your visualisation is becoming far too convoluted with too many dependencies or tasks you may need to simplify your data set.  One way to do this is to report only critical tasks however if that is not possible, look at alternative tools such as the program evaluation and review technique or PERT.

As a final word, it is recommended that a Gantt view be considered to simplify discussions with stakeholders and to inform decision-making in your projects. More importantly, keep developing new tools and techniques for your projects and who knows, you may have the next great innovation that will be used for the next 100 years just like Henry Gantt’s has been.