Project managers frequently use Gantt and PERT (Project Estimation and Report Technique) charts to show the constituent tasks within a project. These two charts are the most popular project management charts. Gantt charts and PERT charts are both very useful project management tools for visually communicating project information. They are both used to schedule tasks, keep the project on schedule and ensure that the timeline is met in accordance with the original project plan.

Depending upon the duration or complexity of a project, the effort may be broken down into phases or iterations, and those then broken down into tasks within each phase or iteration. Both the Gantt and PERT chart would be broken down in a similar manner, potentially using a new chart for each phase, or connecting them to convey the entirety of the effort. Gantt charts have milestones at the completion of key deliverables, while PERT charts utilize review tasks or ‘dummy’ activities at the end of each phase, during which the deliverables of that phase would be validated or as placeholders indicating an intersection of subtasks into one deliverable.

Each tool, however, has their respective strengths and weaknesses. The fact that both of them are quite easy to produce using project management software adds to the confusion between the two project management charts.

A key difference between Gantt Charts and PERT charts is the manner in which flow is conveyed. A PERT chart is essentially a flowchart, or network diagram, while the Gantt chart is a bar chart with volume of time determining how big the bar will be. PERT charts focus on the sequence of tasks and their dependencies between one another while Gantt charts focus on the time required for each task.

PERT Advantages and Disadvantages

PERT Chart Example

These types of project charts were created in order to work on large projects with a great deal of unknowns and a large number of dependencies. The PERT chart starts off with what’s called an initiation node that then splits off into a network of tasks. A PERT diagram could end up with parallel and interconnecting task networks. As a result, when there are many interlinked tasks within the project, a PERT chart can end up looking being fairly complicated, and might cause more confusion for those unfamiliar with them. Frequently, Gantt charts, with their familiar calendar-like presentation are used in conjunction with PERT diagrams to convey projected scheduled.

The PERT chart is an effective way to display complex projects. A project is made up of a group of tasks. The critical path can readily be identified on a PERT chart. The critical path is series of tasks through the project which require the greatest amount of time to complete. A project will take as long as it takes to achieve all of the tasks in the critical path. The non-critical paths, can consume all of their slack with delaying the project.

Advantages of PERT Charts

• PERT diagram’s Critical path conveys important activities which can cause the project to run over.
• Critical path on PERT chart allows focus of resources and effort to reduce risk.
• Allows visibility into possible extreme delivery dates using PERT estimation as a result of potential opportunities to be exploited or risks which to mitigate.
• Excellent for projects focusing on research or new technologies.
• Lets the project manager manage to the critical path.

Disadvantages of PERT Charts

• Can become confusing for the uninitiated or when projects have complex task relationships.
• If some activities take longer than expected, the critical path originally being managed to might end up being wrong. If other paths are near the critical path, they, too should be managed diligently to prevent project overruns.

Gantt Advantages and Disadvantages

Gantt Chart Example

Gantt charts emphasize the time it takes to complete tasks. The Gantt chart is a type of bar chart that illustrates a project schedule, focusing on task timing. A Gantt chart, with its calendar-like schedule, makes it very easy to show the timeline for a project. Each individual task is shown with a bar representing the duration of that task. Gantt charts show the beginning and ending dates of the project and roll-up tasks. They are useful for planning and scheduling projects since it is graphical representation of the duration of tasks against the progression of time.

However, when there are multiple dependencies lining up for a given milestone, the lines frequently intersect or overlay, making it nearly impossible to determine which tasks are the true predecessors. The original Gantt chart didn’t even have this means of conveying dependency. The connecting lines to do were introduced later as a convention to provide this crucial aspect of project planning. As such, Gantt charts don’t show dependencies very well for more complicated projects.

Gantt charts are quite suited for project which are clear-cut and won’t need constant rearrangement and adjustment as the project continues. The Gantt chart depicts the amount of time a given task should take and the required resources for each task. In doing so, the Gantt chart quite suited to assessing the status of the project. It’s quite easy to tell if a task is completed by the time it should be. The only issue with that would be large tasks, wherein it is difficult to tell an accurate percentage of completion, which is part of all project management, regardless of the tool used to convey the schedule.

Advantages of Gantt Charts

• Provide an excellent presentation tool for illustrating sequence of the task and demonstrating individual resources scheduled to time.
• A Gantt chart shows the steps by which tasks should be carried out.
• Easy to identify what should have been achieved at any point in the schedule.
• Makes it easy to ensure that the project is completed on time.
• Easy to prepare, manage, and present.
• Easy to show the importance of special checkpoints with milestones.
• Ability to set meeting points or reviews of the project.
• It is best used to show summary of the whole project to the top management as it does not show detail information for every activity.

Disadvantages of Gantt Charts

• Estimates must be completed before the chart can be drawn.
• Do not effectively convey task dependencies in more complex projects.
• It is difficult to show two sets of dates when using techniques such as earliest start date and latest start.
• It fails to show the critical and non-critical tasks.
• Changes to the schedule require a redrawing of the chart.
• Resource assignments are not easy to illustrate.
• Several scheduling possibilities cannot be shown in the same chart.
• It does not highlight Work Breakdown Structure (WBS) elements with the highest risk of failure or delay.

Summary of Differences between PERT and Gantt charts:

1. A PERT chart is essentially a flowchart, or network diagram, while the Gantt chart is a bar chart.
2. PERT charts focus on the sequence of tasks and their dependencies between one another while Gantt charts focus on the time required for each task.
3. Gantt charts handle sequence and duration, while PERT charts manage large and complex projects with variable duration tasks.
4. Gantt charts focus on the time required to complete a task; whereas a PERT chart focuses on relationships between the tasks.
5. Gantt charts are straightforward and are not made for projects which will experience change; while PERT charts are intricate and tolerate great deals of unknowns.

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Since this book was originally published in 1913, its copyright has expired, and the work is now available through the public domain.  You can read this book on Google and even download the PDF version.  http://books.google.com/books?id=p2ANAAAAYAAJ

Enjoy!

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Since 50% of FastTrack Schedule’s users are not very experienced with project management software , they designed their project management software with ease-of-use as a paramount concern.  Since every project manager, whether one by training or by task, needs to show project estimates and project completion to the stakeholders and project sponsors. AEC’s FastTrack has a reporting module that works perfectly for this.  It also integrates with other mainstream project management tools like Microsoft Excel and Microsoft Project.

Their project management software handles project consolidation as well – empowering you to manage several projects within a single project file.  The resources layout tool enables you to track the contributions of project participants over time, including scheduling project personnel and resolving conflicts which undoubtedly arise when you have someone who’s 250% allocated.  The reporting piece allows you to archive a snapshot of the project and drop it into a PowerPoint presentation so you can mail that off to all of the stakeholders..

But here’s something you don’t frequently get with other project management software — It’s cross-platform.  This means that your back-office team can see the share project files with the creative team so devoted to their Macs.  Now, finding Mac Project Management Software is frequently hard enough, but here you get a solution that works all around.  I know people will be excited to hear that there are more choices when looking for Project Management Software for the Mac.

The price of FastTrack Schedule is $350 per license. You can learn more about their product at AEC Software .

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What is the definition of a Gantt Chart?

A Gantt Chart is a first-rate tool when used by PM’s that seek to envision, prepare, and track estimated and true progress of projects. Its graphical way of showing data its executive leadership and front-line staff alike to readily recognize the flow of a project, without necessitating a full tutorial about project management.

Each occasion we, in our project management careers , go through the efforts of our working lives, toiling to meet and exceed the self-set targets, a quiet moment of appreciation extends onward to Henry Gantt for innovating this easy-to-use diagram to communicate project schedules, as the timeline makes it possible for us to excel as project managers.

Additional Resources

Project Timeline Sample Gantt Chart

Background

Henry Gantt

Henry Gantt was a management consultant and engineer. Henry Laurence Gantt devised the Gantt chart in the 1910’s. At that time, Gantt Charts were quite innovative and unheard of. Huge construction projects like like the Hoover Dam and the Eisenhower National Defense Interstate Highway System necessitated a tool such as the Gantt diagram,

Now, a staple project management tool and buzzword in every leader’s repertoire of modern project administration tools today, Gantt Charts are routinely deployed in the by PM’s, planners, and system developers. Working on projects without them is unthinkable, except in the rare case when the inherent nature of the work does not require them.

The Gantt Chart has found universal status, known in French as diagramme de Gantt and Spanish as carta Gantt, graficas de Gantt, and diagrama de Gantt], indeed the whole world speaks this common language of project representation.

HL Gantt’s global contribution to the modern project management is honored today through the Henry Laurence Gantt Medal. This medal, established in 1929, is awarded for distinguished achievement in management and service to the community.

Practical Application

So, how does someone use a project plan? These charts are generally introduced during the planning and scheduling stages of projects. A visual tool, the charts allow us to obtain a bird’s eye view of the project in its totality. From beginning to the end, the charts force us to:

1. Make a realistic assessment of the end-time of the project.
2. Align the effort (or phases) – in sequential order, as well as in parallel.
3. Think in terms of task dependencies – which task is dependent on what.
4. Concentrate on the necessary resources, both when and where, throughout the run of the project.

After the project timeline charts are drawn, and project execution begins, we start comparing our actual, ground-level performance against what was planned. This comparison is possible by checking the field reports against the project Gantt charts. Thus, we get to benefit from them in two immediate ways:

1. To observe work in progress. At the minimum, a percentage of completion can be worked out, by taking a snapshot of the progress “right-now”, and comparing it with the chart, for the “right-now” point of time. If there are any slip-ups in terms of time or cost, we are forced to question our optimism (or hope?) that the tasks would get completed earlier then they actually did, at the planning stage. This introspection helps in more realistic planning for a now more matured manager in their future projects.
2. To also consider ways to speed up future tasks, while there is still time, to ensure completion by the total project’s estimated deadline. Perhaps resources (better manpower, more funds, or additional material) need to be allocated far in advance for a task that is going to be initiated later down the line? Maybe a task or two can be rescheduled more efficiently, in order to meet some unforeseen contingencies that occurred after project initiation?

How to Create a Gantt Chart

A Gantt Chart, after all this mess, is just a chart with rows and columns. One simply writes all the tasks, one below the other, so that each task occupies a single row. Alongside the names, columns are drawn to indicate the dates. The dates may be in increments of days, weeks or months. Depending on the total length of the project, we may decide the granularity of the date increments which is appropriate – days, weeks or months.

Now, for each task in a row, we draw a horizontal (preferably hollow) bar alongside, with its start point in the column representing the date when it is scheduled to begin, and the end point in the column of the date when it is expected to end. Once these horizontal bars are drawn, we step back and get to observe the tasks that are going to run sequentially, in parallel, or overlap.

After the project has started, PM’s just fill in the hollow bars to a length that is in proportion to the fraction of the work that has been completed, for every task. In order to judge where we stand on any given date – say today, we can draw an imaginary vertical line through the chart at the current date – this is a “snapshot line”. The tasks that are supposed to have completed fully shall be to the left of this snapshot line. If they are indeed completed, their hollow bars shall have been completely filled. Partial filling indicates slip-ups. Tasks that are crossing the snapshot line are current tasks in hand; well, at the least they are tasks that were scheduled to have begun before today. If the horizontal bar on such tasks is filled in to the left of the line, then the current tasks are behind schedule; if they are filled in to the right of the line, then they are ahead of schedule. Future tasks, of course, will lie completely on the right of the snapshot line.

Complex projects

The aforementioned description is for simpler projects. Ideally, tasks in simple projects would not go beyond a single page, which makes them manageable. Often, and especially in complex projects, each task may be broken into smaller and more easily manageable subtasks. These subtasks may be moved to subordinate charts, with their own timelines. In management terminology, the process – of breaking up of these tasks into independent unit-tasks that can be completed on their own – has been given an exotic name of Work Breakdown Structure. The Work Breakdown Structure enables the project coordinator’s mind to grasp the project in its entirety as well as to think in terms of allocating resources, assign responsibilities, and measure and control the project, for every task and sub-task.

Further, in team-oriented projects, where each task is to be handled by different personnel, there might be an additional column against each task, where initials of these personnel may be entered, to identify who is supposed to be doing what.

Project Milestones

Finishing milestones are occasions for celebration, to pop the champagne. They help to boost the morale of personnel involved in making the project a success. If the project timeline is drawn up along with suitable (and achievable!) milestones, by using some special symbol such as brightly-colored diamonds, and the chart is kept in some centrally visible place, it would motivate all the people to achieve them. These milestones could range from perhaps the approval of project design by the customer, or completion of project prototype, to delivery of individual modules by different teams.

Conclusion

Since HL Gantt guided us toward enlightenment, such a library of books about management have been written on managing projects. Indeed, Project Management is a full-fledged discipline in itself, deserving of a separate academic degree for those who pursue it as a career and profession. More powerful models have evolved in the past few decades, which strive to capture the complexity of human endeavor and track and monitor its progress. The schedule continues to be used in some avatar or the other in all such models. And for simple projects, The project timeline is the solution.

A Gantt Diagram is a graphical demonstration of work effort as segments of work across time. It aids planning and tracking of project development and resource allotment. On the left-hand section of the Gantt Diagram flows a column with the WBS (essentially, a series of tasks). The chart component shows time progression, conveyed either in absolute or relative time.

When building a Gantt Diagram, each unit of work consumes one row. Dates go across the top, staggered as appropriate to the enormity of the project under review. Bars are shown as rows in the Gantt Diagram depict the beginning and end times of every piece of work in the project. Tasks may happen concurrently, one after the other, and overlap.

Practically every planning and scheduling of projects software (like Basecamp) allows project management through Gantt diagram representation of project workflow. These tools provide managerial toolsets to start, track and report projects.

Gantt Chart Example

Gantt Chart History

The Gantt Diagram was invented by Henry L. Gantt, an American engineer, in 1917. Henry Laurence Gantt came up with the prototype of the Gantt chart around World War I. The chart proved to be so powerful and useful that it has remain unchanged for practically a century. Ultimately, in the 1990’s when Gantt Charts were modified to include linkage lines between tasks.

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Henry Gantt

Henry Laurence Gantt worked as a management consultant as well as a background in mechanical engineer by trade.  Henry Gantt is known for creating his self-named easily-viewed scheduling and monitoring diagram. One creates Gantt Charts to reveal planned and actual project progress.  A commonly accepted project management instrument these days, it was an innovation of world-wide significance in 1920, founded on Mr. Gantt’s work while ship building during WWI. Changing history forever, Gantt charts have subsequently been used to schedule and monitor large construction projects like the Hoover Dam started in 1931 and the Eisenhower highway network launched in 1956.

Henry L. Gantt Biography

Henry Laurence Gantt was born in Calvert County, Maryland, USA. He graduated from McDonogh School in 1878 and Johns Hopkins College. After working as a teacher and draftsman, he pursued mechanical engineering. In 1887, he joined Frederick W. Taylor in the leveraging the theory of scientific management of Midvale Steel and Bethlehem Steel, where they worked together until 1893.

Later in his career as a management consultant, in addition to the Gantt charts, he futher made scientific management history by devising the ‘task and bonus’  system.  The theory behind the ‘task and bonus’ method of wage payment (1901) was that it would create greater worker efficiency and productivity by rewarding the tasks monitored via Gantt charts.  Directly countering the piece work pay system of Taylor, which also penalized poor performance, Henry Gantt’s method allowed workers to earn their regular rate with an additional bonus for accomplishing their target productivity.  This allowed workers to maintain a stable salary while they were learning the job, and rewarded them for leveraging this additional proficiency.

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