Gantt diagram

The Gantt chart is a graphical tool whose objective is to expose the expected time of dedication for different tasks or activities over a given total time. Despite this, the Gantt chart does not indicate the relationships between activities.

Definition

A Gantt chart, or harmonogram, is a type of bar chart that illustrates a project schedule.

This chart lists the tasks to be performed on the vertical axis, and time intervals on the horizontal axis.

The width of the horizontal bars in the graph shows the duration of each activity.

Gantt charts illustrate the start and finish dates of the terminal elements and summary elements of a project. Terminal elements and summary elements constitute the work breakdown structure of the project.

Modern Gantt charts also show the dependency (i.e., precedence network) relationships between activities. Gantt charts can be used to show current schedule status using percent-complete shadings and a vertical “TODAY” line.

Gantt charts are sometimes equated with bar charts.

Gantt charts are usually created initially using an early start time approach, where each task is scheduled to start immediately when its prerequisites are complete. This method maximizes the float time available for all tasks.

Origin

In 1896 Karol Adamiecki developed a new means of graphical representation of interdependent processes that are designed in order to improve the visibility of production schedules.

Given the position of each task over time, relationships and interdependencies can be identified.

In 1931 a more widely known article was published to describe Karol Adamiecki’s diagram, who called it the harmonogram or harmonograf.

At that time, a similar method had been popularized in the West by Henry Gantt (who had published articles on it in 1910 and 1915). With minor modifications, the Adamiecki chart is now more commonly known in English as the Gantt chart, as it was Henry Laurence Gantt who, between 1910 and 1915, modified and disseminated this type of chart in the West.

For this reason, planning the development of complex projects (greater than 25 activities) also requires the use of techniques based on precedence networks such as CPM or PERT diagrams.

These networks relate the activities so that the critical path of the project can be visualized (that is, the most complex activity or the one that will take more time) and allow to reflect a time scale to facilitate the allocation of resources and the determination of the budget.

The Gantt chart, however, is useful for establishing a basic relationship between time and workload.

In project management, the Gantt chart shows the origin and end of the different minimum units of work and the groups of tasks (called summary elements in the image) or the dependencies between minimum units of work (not shown in the image) .

Since its introduction, Gantt charts have become a basic tool in the management of projects of all kinds, in order to represent the different phases, tasks and activities scheduled as part of a project or to show a timeline in the different activities, making the method more efficient.

Basically, as already mentioned, the diagram is made up of a vertical axis where the activities that constitute the work to be executed are established, and a horizontal axis that shows the duration of each of them on a calendar.

Gantt chats as a Dev Management tool

A Gantt chart can be made with a spreadsheet in a very simple way, marking certain cells to form the representation of each task. There are macros that automate this elaboration in MS Excel and Libre / OpenOffice Calc.

However, there are project management tools dedicated to planning and tracking tasks that use the Gantt chart. Tasks are entered and their processes are capable of producing a representation of those tasks over time in the Gantt chart format.