Gantt charts
Gantt charts are sometimes
called as Gant Chart .
The following discussion of
Gantt charts originally appeared in Herrmann (2005)
It is important to note that
Henry 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.
Henry 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),
Henry 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
the Gantt charts 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.
A novel method of displaying
interdependencies of processes to increase visibility of production schedules
was invented (and aplicated) in 1896 by Karol Adamiecki and described in
"Przeglad Techniczny" No 17, 18, 19 and 20 of 1909. In 1931, Adamiecki published
a number of articles popularizing this diagram, which he called the Harmonogram
or Harmonograf. With minor modifications, this chart is now more commonly
referred to as the Gantt Chart.
Gant Chart in Project
Management
Using Gant Chart for project
planning and scheduling
Gant Chart is a graphical
representation of tasks as segments on a time scale. It helps plan and monitor
project development or resource allocation. The left hand side of the Gant chart
is a column with lists of tasks. The horizontal axis is a time scale, expressed
either in absolute or relative time.
In a Gant chart, each task
takes up one row. Dates run along the top in increments of days, weeks or
months. Rows of bars in the Gant chart show the start and end dates of each task
in the project. Tasks may run sequentially, in parallel or overlapping.
Gantt chart example
Use Gantt chart
at project scheduling stage to
-
Assess time characteristics
to a project
-
Show the task order
-
Define resources involved
-
Show links between
scheduled tasks
Use Gantt chart at project
planning stage to
-
Monitor project completion
-
Display the results of
correctional activities
-
Show links between
scheduled tasks
History of a Gantt Chart
Gant chart was created by Henry L. Gant, an
American engineer, in 1917. He developed the first Gant chart for planning
of building ships in the First World War times. The chart proved to be such
a powerful analytical instrument that it had not undergone any changes for
almost 100 years. It was only in 90s of the last century when link lines
between tasks were added to the Gant chart.
References
http://en.wikipedia.org/wiki/henri_Gantt
http://www.conceptdraw.com/en/products/project/ap-gant-chart.php
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