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Gantt Chart
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how the Gantt Chart contributes to project management software, to project comprehension, and to project communication
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gantt chart, timeline, computer timeline, project management software, gantt charts, pert chart, project management tools, excel gantt chart, critical path schedule
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• Gantt Chart
(Wiki definition)
(sample graphic)
(templates of common Gantt Charts)
A Gantt Chart is the most common form of graphic used in project management
software today. It illustrates the sequence of tasks and milestones against a
 timescale, using broadly
recognized symbols such as triangles, rectangles, and arrows
(representing links). Consequently, a Gantt Chart is easily understood
by many, including persons who have never seen the Gantt Chart before.
Because a Gantt Chart is produced mostly by project management software, the
graphic is not widely recognized as a Gantt Chart. Many persons who see the
Gantt Chart for the first time might think of it as simply a timeline.
For a further discussion of the Gantt Chart, and Help-U-Plan's approach to
creating this valuable graphic, see our
information page.
• Timeline
(Wiki definition)
There are many ways we show events and activities having happened over a period
of time. These representations we call a timeline. Sometimes they are mostly
text, and spread out over a sheet of paper with time passage being indicated
with different methods. The arrow of time may be horizontal or vertical.
The Gantt would likely be much more widely used in different publications were it
more commonly known as a Gantt Chart, rather than a timeline. One
difference in usage is that timelines are commonly thought of as representing
history, whereas Gantt Charts commonly represent simulations of the future.
It is likely that with increasing use of the internet to access software and
information, the Gantt Chart will increase in recognition, and be used
to represent history as well as the future.
It is also likely that as use of the internet expands, and advertising covers
more of applications' expenses, that Gantt Chart searches will become more
productive. Also, it will be the case that project management
software and other project management tools which make use of Gantt Charts will be more
easily found by those investing in searches.
Internet searches using the term computer timeline will become more productive,
bringing up different methods for producing the Gantt Chart, as well as other
formats for producing some type of timeline with a computer (computer timeline).
• Project Management Software
Today's project management software can store a vast amount of data, and access
it easily. This amount of data is valuable, even necessary, for large
projects. The problem for project managers is mentally comprehending all of this
data, and communicating about it to others. This is where graphical
representations of data shine. The Gantt Chart is the most common graphical view
of data produced by project management software, since it is the best communicator
to those less familiar with the data.
A Gantt Chart presents separate symbols for milestones (events), tasks
(time-consuming activities), and links (relationships) between these
items. These symbols are presented against a left-to-right timescale.
Consequently, a Gantt Chart illustrates the beginning of a project at the upper
left of the graphic, and ends the project at the lower right. This
upper-left to lower-right is called a 'waterfall' effect.
An interesting aspect of the Gantt Chart is that it permits breakup of a task into
different work efforts, if the complete task has components which need to be
done at different times. For example, in construction projects,
the plumbing task (typically done by a single sub-contractor) would
likely be broken into 'rough plumbing' and 'finish plumbing'.
Rough plumbing would be done early in the project, and finish plumbing near the
end. The two symbols representing each of these sections of work appear in their
appropriate spot timing-wise, and between the tasks which precede and which
follow their work.
The most common symbol format in today's Gantt Charts is to represent a project task as
a rectangle extending from left to right representing the expected duration of the
task. A milestone (or event) is typically shown as a triangle or
diamond. Relationships/dependencies are represented by arrows. Often,
relationships between tasks and milestones are left off the Gantt Chart. Some
people find them offensive; perhaps feeling that a relationship shown as an
arrow suggests a simple relationship or dependency between the tasks when the actual
relationship is more complex.
It is also true that 'the simpler the better', and omitting relationships
produces a simpler Gantt Chart. Even with relationships/dependencies shown,
'simple' describes the Gantt Chart well. Quite a bit of high-level information
is shown on a Gantt Chart, omitting the detail so that important data is
emphasized.
• Critical Path Schedule
The concept of progress/tracking, and the capability of computer-based project
management software to maintain vast amounts of data accurately, has led to the
development and use of the concept of the 'critical path' for a project.
The critical path identifies the tasks which must be done on schedule
(within the time forecast) for the project to be completed on time. These
individual tasks can then be given particular attention by the project manager,
and can be shown in graphical presentations like the Gantt Chart as being the critical
path of activity for the project (critical tasks typically shown in red).
This approach in project management software has become known as the critical path method.
Persons who are responsible for completion of tasks on the critical path can see
at a glance on the Gantt Chart the importance of their own work. This can be a
very important vehicle for communicating with participants, and comes via the
capability for recording and showing detail that is provided by today's sophisticated
project management software.
• Excel Gantt Chart
Gantt Charts are produced on many mediums besides computers. Sometimes Gantt
Charts are drawn hurriedly by hand on paper; sometimes more carefully using
drawing instruments or software. The Excel spreadsheet (or other
spreadsheet) is also used, particularly spreadsheets like Excel which offer
graphic capabilities, and the ability to arrange and rearrange things quickly.
This provides organization and neatness to the Gantt Chart, and makes changes
simpler and more convenient than Gantt Charts done in pen and ink.
Using Excel's VBA scripting capabilities (used in creating macros), one
could likely produce a simple true scheduler with the product being a usable Gantt Chart.
• Gantt Chart History
(Wiki - 6/19/07)
"Henry Laurence Gantt, A.B., M.E. (1861-23 November 1919) was
a mechanical engineer and management consultant who is most famous for developing the
Gantt chart in the 1910s. These Gantt charts were employed on major
infrastructure projects including the Hoover Dam and Interstate highway system and
still are an important tool in project management."
"The following discussion of Gantt charts originally appeared in Herrmann (2005)."
"It is important to note that Gantt created many different types of charts.
Moreover, Gantt designed his charts so that foremen or other supervisors could
quickly know whether production was on schedule, ahead of schedule, or
behind schedule. Modern project management software includes this critical
function even now."
"Gantt (1903) describes two types of balances: the "man's record,"
which shows what each worker should do and did do, and the daily balance of
work, which shows the amount of work to be done and the amount that is done.
Gantt gives an example with orders that will require many days to complete.
The daily balance has rows for each day and columns for each part or each
operation. At the top of each column is the amount needed. The amount
entered in the appropriate cell is the number of parts done each day and the cumulative
total for that part. Heavy horizontal lines indicate the starting date and the
date that the order should be done. According to Gantt, the graphical daily
balance is "a method of scheduling and recording work." In this article,
Gantt also describes the use of production cards for assigning work to each operator
and recording how much was done each day."
"In Work, Wages, and Profits (originally published in 1916),
Gantt explicitly discusses scheduling, especially in the job shop environment.
He proposes giving to the foreman each day an "order of work" that is an
ordered list of jobs to be done that day. Moreover, he discusses the need
to coordinate activities to avoid "interferences." However, he also
warns that the most elegant schedules created by planning offices are useless if they
are ignored, a situation that he observed."
"In Organizing for Work (originally published in 1919), Gantt gives two principles
for his charts: one, measure activities by the amount of time needed to
complete them; two, the space on the chart can be used the represent the
amount of the activity that should have been done in that time. Gantt shows a
progress chart that indicates for each month of the year, using a thin horizontal
line, the number of items produced during that month. In addition,
a thick horizontal line indicates the number of items produced during the year.
Each row in the chart corresponds to an order for parts from a specific contractor,
and each row indicates the starting month and ending month of the deliveries.
It is the closest thing to a Gantt chart typically used today in scheduling
systems, though it is at a higher level than machine scheduling."
"Gantt's machine record chart and man record chart are quite similar, though they
show both the actual working time for each day and the cumulative working time for a
week. Each row of the chart corresponds to an individual machine or operator.
These charts do not indicate which tasks were to be done, however."
• PERT Chart
(Wiki definition)
The PERT (Program Evaluation and Review Technique) Chart is often the
project management software view of data preferred by detail-oriented project
managers, as it presents more data (such as contact information) about
each task than does the Gantt Chart, and presents it all in one location on the
chart, as opposed to breaking the task up into time-based components as does
the Gantt Chart.
For example, in the construction remodel project given above, the Gantt
Chart shows the plumbing task as 2 sub-tasks done at different times during the
project. The PERT chart would show the plumbing as a single node on the
chart, with perhaps a note indicating that the activity will consist of both
rough plumbing and finish plumbing.
Consequently, the PERT Chart does not show graphically the flow of activities
from left to right against a timescale. A little more study is required
by those less familiar with the data, such as upper-level managers or board
members to whom the project manager is responsible.
Gantt Chart Definition
(Wikipedia - 6/18/07)
"A Gantt chart is a popular type of bar chart that illustrates a project schedule.
Gantt charts illustrate the start and finish dates of the terminal elements and summary
elements of a project. Terminal elements and summary elements comprise the work
breakdown structure of the project. Some 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 (also called "TIME NOW" or "DATA DATE")."
PERT Chart Definition
(Wikipedia - 6/19/07)
"The Program Evaluation and Review Technique commonly abbreviated PERT is a model
for project management invented by Booz Allen Hamilton, Inc. under contract to
the United States Department of Defense's US Navy Special Projects Office in 1958
as part of the Polaris mobile submarine-launched ballistic missile project. This
project was a direct response to the Sputnik crisis. Some US government contracts
required that PERT be used as part of management supervision."
"PERT is basically a method to analyze the tasks involved in completing a given
project, especially the time needed to complete each task, and identifying
the minimum time needed to complete the total project."
"PERT was developed in the 1950's, primarily to simplify the planning and
scheduling of large and complex projects. It was able to incorporate uncertainty
by making it possible to schedule a project not knowing precisely the details and
durations of all the activities. It is more of an event-oriented technique
rather than start- and completion-oriented, and is used more in R&D-type
projects where not cost but time is a major factor."
"This project model was the first of its kind, a revival for scientific
management, founded in Fordism and Taylorism. Though every company now
has its own "project model" of some kind, they all resemble PERT
in some respect. Only DuPont corporation's critical path method was invented
at roughly the same time as PERT."
"The most famous part of PERT is the "PERT Networks", charts of timelines that
interconnect. PERT is intended for very large-scale, one-time,
complex, non-routine projects."
• Timeline Definition
(Wikipedia - 6/19/07)
"A timeline describes the events that occurred before another event, leading up
to it, causing it, and also those that occurred right afterward that were
attributable to it."
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