How To Understand A Gantt Chart
Ah…the ubiquitous Gantt Chart. It’s the staple of project managers around the world. It’s almost as if the clouds separated and a ray of light shone upon this most useful of reports. How can so much information be jam packed in one simple report?
With choices ranging from Microsoft Gantt Chart, to a free Gantt Chart template or online software as a service, depending upon the type of Gantt Chart software you are using, you can define milestones, assign resources, check status, and indicate dependencies…all on just one 8 ½ x 11 sheet of paper!
Amazing! The Gantt Chart has become so common in project management that it may be easy at times to take this workhorse for granted. Let’s take a few moments to pause and reflect on the Gantt Charts humble, yet revolutionary, beginnings and how we can make the most of this useful tool.
What is a Gantt Chart?
A Gantt Chart is a matrix of activity that graphically represents the duration of tasks against the progression of time. Time is indicated along the x-axis on the top of the chart (time can be broken down into days, weeks, months, or any other period) and project activities along the y-axis on the left of the chart. A bar chart is then used to illustrate the start and finish dates of a project schedule.
Don’t let the technical and clinical description of the Gantt Chart scare you away. Bottom line? If you want to know who is supposed to do what and when it is supposed to be done, then this is the project management tool to use.
What is the Origin of the Gantt Chart?
Henry Laurence Gantt (1861-1919) is given credit for the creation of this management tool. Henry Gantt was a mechanical engineer and management consultant who focused on worker efficiency and productivity. There may have been earlier versions of this chart available prior to Mr. Gantt, but he was the first to publish and apply in the industrial world. It was used in major projects such as constructing the Hoover Dam as well as the Interstate Highway system. While commonplace today, this graphic schedule for planning and controlling work and recording progress along the way was considered revolutionary at its inception.
Understanding Gantt Chart Dependencies
One of the key features of modern day Gantt Charts is the dependency between tasks. This essential concept that some activities are dependent on other activities being completed helps a project manager optimize their project schedule. The four types of dependencies are:
This is the most common and easiest to understand of the four dependencies. Simply stated, one task must be complete before the next task begins. For example, you can’t begin framing a house until after the foundation has been laid. More sophisticated use of this dependency would be for a task to start a certain number of days (rather than immediately) after another task has been finished.
A second type of dependency would be that a task can start once another task has started. For example, traffic cones may be placed on a highway to redirect traffic. As soon as these were placed on the highway, line painting can begin. This too can be a bit more sophisticated to include a certain number of days after one task has started that another one can begin.
The third type of dependency indicates that a task would need to be finished at the same time as another task. For example, a concession stand at a sports event stops selling refreshments at the same time the game ends. Or, a more sophisticated example would be that two hours before the game ends, alcoholic beverages stop being served.
This is the one that trips everybody up and is used the least. This means that the second task in the relationship cannot finish until the first task starts. But, the second task can finish any time after the first task starts. For example, let’s say you were building a website for a customer and you are going to create an invoice for them. The invoicing process begins when the customer requests the website to be built, but cannot be finished until after the website has been delivered. Confusing? Yes. Good to stay away from? As much as you can.
In conjunction with dependencies on the Gantt Chart, you will also see Milestones used. Milestones are interim goals that mark completion of major components of a project. These zero duration tasks may define the end of a phase or completion of a particularly large deliverable on a project. The use of milestones establishes the fact that progress is being made on a project and that everyone understands what that means in the project lifecycle.
Don’t Miss the Forest for the Trees
The beauty of a simple Gantt Chart is that it allows you to immediately see what should have been achieved on your project at any point in time. Plus, you can see how remedial action on your part may be able to bring the project back on track. But, don’t just run your project from this one report….as amazing as it is. There are many other nuances to the ebb and flow of your project and you must be in tune with all of them.
There are project managers that will sit at their desks and behind their computers and send out notes of chastisement to their teams if they start seeing their planned-to-actual numbers slip on the Gantt Chart. Don’t be that type of project manager. Know what is going on with your project on a first hand basis and understand the intricacies that are occurring on the front line. Having these conversations with your valuable resources (also known as ‘people’) will allow you to effectively manage your projects with your eyes wide open and a full set of tools at your disposal.
That’s how you should view a Gantt Chart. A powerful and insightful tool that can help you navigate your team through uncertain project waters.
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