Gantt and PERT Chart Tools in Project Management

Critical Chart Choices in Project Management

"One look is worth a thousand words." — Barnard (1920s, as cited in Lutz, 2009, p. 7)

Just as a project manager must evaluate alignment, benefits, and risks — as well as other business and project factors — when considering which projects to manage, the project manager must also routinely make critical chart choices. During the course of a project, the manager must assess whether Gantt charts, critical path analysis, task tracking, time capture, Program Evaluation and Review Technique (PERT), or another chart type will best serve to estimate the project's completion.

In Project Portfolio Management: A Practical Guide to Selecting Projects, Managing Portfolios, and Maximizing Benefits, Levine (2005), a project management specialist and consultant since 1962, asserts that tactical management systems range from the management of individual projects to the management of programs packed with projects, and may ultimately ascend to the management of asset allocation criteria that numerous initiatives, programs, and projects support. This paper presents historical and contemporary information regarding Gantt and PERT — two tactical tools regularly used to help manage projects — and shares considerations to help one evaluate a number of similar chart tools.

History of Gantt Charts

Accounts of the history of the Gantt chart vary. In An Introduction to the History of Project Management, Chiu (2010) names Henri Fayol (1841–1925) and Henry Gantt (1861–1919) as the forefathers of 20th-century project management. In 1916, Fayol published Administration Industrielle et Generale, which describes five primary management functions that ultimately comprise the basis of project management. "The five primary functions of management that he specified are planning, organizing, commanding, coordinating, and controlling" (Chiu, 2010, p. 4). Fayol's theory established a stronger scientific foundation for contemporary project management.

As Gantt extended Fayol's theory, he reportedly developed the Gantt chart around 1917, with the resulting charts and diagrams permitting processes to be charted and controlled. According to Chiu:

An example of their [Gantt chart's] application occurred during the First World War in constructing ships for the U.S. Navy. Gantt documented and analyzed the shipbuilding process step-by-step, which enabled him to assess and provide data about how the management functions outlined by Fayol interrelated. Gantt charts have remained a significant aid in project management. They have been used for major government projects, including in the construction of the Hoover Dam (1931–1936) and the U.S. interstate highway system. As a project management tool, their impact has been and continues to be immense. (Chiu, 2010, p. 4)

Chiu (2010) reports that both Fayol and Gantt studied and drew inspiration from the theories of Frederick Winslow Taylor (1856–1915), presented in his text Scientific Management, to develop the Gantt chart. The web publication What Is a Gantt Chart? (2010), however, asserts that Karol Adamiecki, a Polish engineer who managed a steelworks in southern Poland and had a keen interest in management ideas and technique, devised the Gantt chart prototype in the mid-1890s. According to this source, approximately 15 years after Adamiecki, Gantt devised his own version of the chart, which then became popular in Western countries — ultimately leading to the name "Gantt" being associated with this type of chart. In time, with the advent of computers and project management software, Gantt charts that were once laboriously prepared and updated by hand came to be easily created, updated, and printed.

How Gantt Charts Work

The Gantt chart represents one of the oldest techniques that manufacturing and service organizations routinely use for the planning, controlling, and scheduling of projects. In Prod & Oper Mgmt, 2E, Saxena (2009) explains that the Gantt chart — also known as a "bar chart" — graphically represents "a series of activities drawn to a time scale. The horizontal axis (X-axis) represents time and the vertical axis (Y-axis) shows the activities to be performed. The Gantt chart shows activities assigned to specific jobs at individual work centers by horizontal bars" (p. 175). The horizontal bar's position and length depict the designated activity's start and completion dates.

Although the project manager initially prepares a Gantt chart for planning purposes, the chart also depicts actual performance or progress as the project moves forward. This provides a clear picture of any variations from the planned timeline. The Gantt chart also enables a comparison between the initially planned time and the actual time required to complete a particular activity and/or project (Saxena, 2009).

In addition to portraying the projected time for each task and how far each task has progressed, a Gantt chart relates both sequential and simultaneous tasks. The project manager can quickly identify which tasks overlap. In System Analysis and Design, Dennis, Wixom, and Roth (2008) assert that the Gantt chart "can communicate the high-level status of a project much faster and easier than the work plan. Creating a Gantt chart is simple and can be done with a spreadsheet package, graphics software (e.g., Microsoft Visio), or a project management package."

A Gantt chart conveys the same task information as a project work plan, but in a graphical manner. During the first step of creating a Gantt chart, the individual lists the tasks as rows in the chart. Based on the needs of the project, the project manager lists time across the top in increments — dividing a short project into hours or days, or segmenting a medium-sized project into weeks or months. Horizontal bars are drawn to depict the start of each task, spanning the duration of each task and extending to mark exactly when the task will end. As individuals work on various tasks, the project manager proportionately fills in the appropriate bars to designate how much of each task has been completed. The position of the fill relative to a vertical line drawn from a particular date gives the project manager a clear picture of whether tasks are ahead of schedule, on time, or behind schedule. When a bar "is not filled in and appears to the left of the line, that task is behind schedule" (Dennis et al., 2008, p. 90). A bar filled to the right of the line indicates the task is ahead of schedule.

Limiting the number of tasks on a Gantt chart to approximately 20 to 30 works best, as including too many tasks can prove confusing. When the number of tasks exceeds this range, it may be preferable to divide the tasks into subtasks and generate charts for each level of detail.

The publication What Is a Gantt Chart? (2010) further explains that the chart lists activities on the left side, with a suitable time scale across the top. A bar represents each activity, with its position and length reflecting the start date, duration, and end date of the activity. This format allows one to easily see:

Conclusion: Choosing the Right Chart Tool

In addition to Gantt, PERT, and CPM charting tools, a number of other chart types — as well as combinations and variants — can help manage a project by computing its time and activities. Today, project managers regularly use Gantt and other charts to track project schedules and portray additional information about a project's diverse tasks or phases, including the progress of each task and the resources utilized.

Levine (2005) frames the broader context well: project portfolio management (PPM) represents more than an expanded application of project management. The emergence of PPM as a recognized set of practices may be considered the biggest leap in project management technology since the development of PERT and CPM in the late 1950s. PPM revolutionizes the way we look at projects, the impact projects have on the health of a business, and the governance of projects. By evaluating benefits, risks, alignment, and other business and project factors, organizations can prioritize candidate projects and allocate limited economic and human resources most effectively. Core competencies — Gantt charts, critical path analysis, task tracking, time capture, and completion estimates — remain as central today as ever before.

When making routine critical choices regarding which chart type to use to track time and activities, the project manager can benefit not only by considering which form best meets the project's needs, but also by considering which one ultimately provides the clearest and most actionable picture of the project's progress.

References

Chiu, Y. C. (2010). An introduction to the history of project management. The Netherlands: Eburon Uitgeverij B.V.

Dennis, A., Wixom, B. H., & Roth, R. M. (2009). System analysis and design. Hoboken, NJ: John Wiley and Sons.

Levine, H. A. (2005). Project portfolio management: A practical guide to selecting projects, managing portfolios, and maximizing benefits. Hoboken, NJ: John Wiley and Sons.

Lutz, F. I. (2009). Words that work: It's not what you say, it's what people hear. New York, NY: Hyperion.

Project management critical path method — Program evaluation & review technique (CPM/PERT). (2011). Retrieved July 19, 2011, from http://www1bpt.bridgeport.edu/sed/projects/cs597/unfiled/zhipingli/report.html

Ravindran, A. (2008). Operations research and management science handbook. Boca Raton, FL: CRC Press, Taylor & Francis Group.

Saxena, J. P. (2009). Prod & Oper Mgmt, 2E. New Delhi: Tata McGraw-Hill.

Schwalbe, K. (2010). Information technology project management. Florence, KY: Cengage Learning.

What is a Gantt chart? (2010). Gantt.com. Retrieved July 20, 2011, from http://www.gantt.com/