A brief history of
Gantt charts
Introduction
• It is difficult to envisage how a modern
project would be managed without at
some point creating a chart of tasks to
be done in delivering the project’s
declared benefits. One of the most
enduring types of chart is the Gantt
chart.
In its most common modern format this plots a list of
deliverables on one axis against time on the other
axis. The concept was first developed around the turn
of the 19th Century by American Henry L. Gantt, who,
working with a colleague Frederick Taylor devised a
method of describing production planning and
resource loading for factories and workshops. In
truth, the first ‘Gantt charts’ were more like tables
than charts, though this was one of the first instances
of the deliverable-vs-time concept.
• In a quite different age where
people’s word was their bond,
the Gantt chart was charmingly
described thus:
If a promise of a delivery is to be kept, all the work in a plant must be planned so accurately that
when a new order is received, it is possible to tell almost to a day when the work will be completed.
The Gantt progress chart enables the manager to keep before him all the promises he has made, to
concentrate his attention on overcoming obstacles and avoiding delays, and, when it is impossible to
live up to a promise, it enables him to give the customer advance notice of the fact. (Wallace Clark –
ref.1).
• Before computers, Gantt charts were drawn by hand as Bar Charts, a term that
has since become synonymous with ‘Gantt chart’, and these required manual
revisions each time something changed. A simple Gantt chart might have looked
like this:
As modern computers became more powerful
it became easier to write programmes that
calculated the impact of linking logic on
deliverable dates, and crucially allowed
changes in critical path, float and so on to be
displayed quickly on screen and hard copy
reports. The advent of graphical user interfaces
such as Windows and the Macintosh allowed
planners to manipulate logic, time and
resource loading on screen. It became possible
to overlay the linking logic onto the Gantt
chart, although in a complex programme this
could become difficult to follow (and is often
best shown in a PERT chart)
• If there was a precedent logic linking one
task to another, it would normally be
shown by the start of task two being
drawn following the completion of task
one, and so on. Critical paths could be
highlighted easily enough, but manually!
• The speed of modern PCs allows ‘what-if’
modelling to be done almost instantaneously
• The calculations needed to maintain
overlapping logic, leads, lags and ladders could
easily be handled by the computing power of
our age (although there are documented cases
where this went badly wrong).
Thank you for attention!