Gantt Chart

The Gantt Chart: A strange addiction that we need to get out of

There is nothing else in the history of management that has had a bigger influence than the Gantt Chart; the famous bar chart used to illustrate project schedules.

Henry Gantt, born in 1861, was an American engineer and management consultant. He studied mechanical engineering at Stevens Institute of Technology, graduating only a year after Frederick Taylor. He then went to work for Midvale Steelworks in Philadelphia, where he met and worked together with Taylor for over a decade. During that time, Gantt was significantly influenced by Taylor’s ideas on scientific management. In 1901 Gantt left and became an independent consultant, publishing over 150 titles and 3 major books.

Despite his great intellectual work, it was not Henry Gantt that popularised this type of bar chart but Wallace Clark, a member of his consulting firm. One of the first major applications of Gantt charts was by the US army in World War I. Although the Gantt chart is more than 100 years old, it has been remarkably resilient, despite numerous innovations since then.

A brief history of planning

Following the popularisation of the Gantt Chart in the early 20th century, two scheduling innovations happened in the 1950’s. The Program Evaluation and Review Technique (PERT) and the Critical Path Method. These enabled the analysis of more complex relationships between tasks and with higher precision. But despite being more sophisticated scheduling techniques they did not replace the Gantt Chart. Instead, they complemented it, creating a more complete visual solution.

In the 1960’s, the American Department of Defence created the Earned Value Management technique, linking cost, time and progress. This complement even more the Gantt Chart. In the 1990’s, Eliyahu Goldratt introduced the Critical Chain Method, focusing more on how constraints and human resources influence schedules.

With the advent of information technology, different project management software packages (i.e. MS Project) used the Gantt Chart at their core of their User Interface. This took the Gantt Chart’s popularity to new heights.

Before analysing the limitations of the Gantt Chart as a planning tool, I would like first to focus on the key concepts of planning and forecasting.

The difference between planning and forecasting, and why it matters

Dr E. F. Schumacher, a prominent 20th century British-German economist talks in his influential book Small is Beautiful (1973) about the existing confusion between terms like planning, budgeting, forecasting, and estimating. He says that economists and politicians have been using these terms interchangeably, yet they are so different.

Dr Schumacher draws a distinction between acts and events. Acts are planned actions within our control while events are uncertain situations that happen outside of our control and cannot be planned. As such, risks are uncertain events that can have either a positive impact (opportunities) or a negative impact (threats).


Organisational leaders traditionally focus on predictability and control. They employ an army of professional planners and forecasters, use Gantt Charts, make Soviet Style five-year plans, and create foresight reports, in an effort to predict the future.

Unfortunately, our obsession to predict the future has existed as long as there have been humans. In ancient Greece, politicians and simple people would go to Pythia, the Oracle of Delphi, to learn about the future. But also, many of the major religions have prophecies about the future.

It seems that we have a very strange relationship with time. We want to treat the future like the past, extrapolating from previous knowledge and events. But why is it so hard to predict the future of an organisation, an economy, or a country?

First, the future is not deterministic, just waiting for us to discover it. Nature follows more chaotic and unpredictable patterns. But somehow we focus too much on what is predictable (seasons) and ignore what is largely not (weather patterns). As mentioned before, there are events that will always be outside of our control and don’t follow a linear path.

Second, and most importantly, and as Dr Schumacher mentions, “Human affairs are largely unpredictable”. This is due to our freedom of choice but also our ability to continuously sense and adapt to events. Improvisation comes more naturally to us than a mechanistic choreography of predetermined moves. Improvisation is both about control and surrendering to the flow. It is about striking a balance between exploring the endless possibilities and exploiting the familiar paths.

But we are not always improvising. Sometimes, our behaviour can have a level of predictability but creativity and innovation come from the unpredictable elements of our behaviour.


A plan is a statement of intention, an accumulation of future actions. Essentially, the goal of a plan is to make the future different from what it would have been. Plans assume that nothing is predetermined, and that we can influence the future to our benefit.

But should all our planned actions be fixed and certain? As mentioned earlier, there are many uncertain events that fall completely out of our control and we need to anticipate them in our plans. We cannot view all future work as a lab experiment with controlled conditions, like a closed system. But rather as an open adaptive system that coevolves with its environment.

Of course, when it comes to automated industrial processes, things are more fixed and certain, with almost full predictability. However, there is a deep conceptual error when we take this logic and apply it to human systems. Plans that involve humans have an inherent uncertainty and need a different paradigm than the scientific management principles of the Gantt Chart.

Our planned actions rely on specific assumptions and predictions. We use assumptions to signal that our planned intentions rely on the anticipation of specific uncertain events. If these turn out wrong then our plans become irrelevant and need adaptation. Unfortunately, once a plan is ready, no-one really pays attention or is even unaware of the planning assumptions. As a result, most stakeholders end up mixing plans (list of actions) with forecasts (controlling the future) as if every variable is under control and fully predictable.


The more long-term, large-scale, and ambitious our plans, the more we treat them as forecasts and the more they become a game of chance, full of uncertainty and randomness. But there are no oracles and fortune tellers, neither there is a time machine that we can use to go back to the future.

The biggest paradox is that we make very long-term plans that we constantly revise, wasting enormous amounts of time and effort. Instead of creating more short-term plans (list of intentions) and more often with more limited assumptions. There is no real reason for creating a monstrous plan and then pay people to maintain it.

What is even more interesting is that by using refined techniques, such as MS Project or other Gantt Chart style tools, we think that our plans are more accurate, while our stakeholders feel more confident. Through its precision it carries conviction. However, as scientists have been saying since the 1960s, fitting something to a mathematical expression doesn’t make it more accurate.

As the economist Dr Schumacher mentions in his book, instead of long-term forecasts we should focus on conducting feasibility studies. Then use our best understanding of the current situation and the results of our studies to make the best informed judgment. It is better to have a crude treasure map rather than having a refined, detailed map. The former makes you think, sense, and adapt, while the latter tricks you into stop thinking. This is why it is so important to once and for all get rid of forecasts. Yet, it is simpler and easier to try and predict the future like an oracle rather than run costly feasibility studies.

The principles behind the Gantt Chart

The Gantt Chart is simple, intuitive and useful representation of project tasks and durations. It helps coordinate a large number of interdependent tasks, highlight the critical path, see delays, and create the right focus.

But most importantly it is a great visual communication tool for teams, stakeholders, and business executives. It is in fact this last point that has given the Gantt Chart such prominence. People love seeing the visual representation of activities, even if the content of the chart is wrong. It creates confidence that we know what we are doing, the future plan is clear, and we can control it.

As mentioned earlier a plan is a statement of intention. The goal is to shape the future in a preferable way. However, as discussed before, a plan is based on assumptions and predictions.

We intend to take actions that are within our control, knowing that there will be events outside of our control.

Apostolos Tzouvaras

But plans, can refer either to the past, as a log of what happened, or to the future. However, more often than not they refer to the past. We check our plans to see if our actions had the result we expected.

However, things start to seriously break down, when stakeholders and everyone apart from the planner confuse the plan with a forecast and the planner for an oracle. Intending to do specific activities in a specific sequence is fundamentally different from the activities actually happening as originally intended. What mattes is always the outcome.

Gantt’s philosophy

First, I think that it is important to understand what was on Gantt’s mind. Henry Gantt was heavily influenced by his mentor, Taylor, and the principles of scientific management. More specifically, the principles of rationalism, positivism, and reductionism, which dominated the early 20th century.

Positivism means that all information is interpreted through logical analysis and reasoning with every task analysed, measured, and optimised. There is no metaphysics, there is only what we see. As such, there is only one best way of doing a task and we need to select the best person and train them to execute it following the prescribed optimal way (rational thinking).

In addition, organisations are considered complicated machines that do interdependent activities in a prescribed way while workers are cogs in the machine. No matter how complicated the system of work is, it can be fully explained by its constituent parts (reductionist thinking).

Of course, we know that this way of thinking, which emerged at the peak of the industrial revolution, is quite limiting today. However, in the last 40 years, there has been a better understanding of complexity with organisations and people seen as Complex Adaptive Systems with emergent properties rather than predictable cogs in a machine. Today we know that that uncertainty is a key part of reality.

Limitations of the Gantt Chart

Gantt originally created his tool for systematic, routine operations in the factory. He was mainly concerned with optimising the use of resources for routine activities and increasing productivity. He designed his visual tool to monitor and control the productivity of individuals, but also measure the daily production balance, quantity of work per machine and so on. Essentially, it was a quantitative control and reward mechanism that created performance accountability to individuals, treating both individual and machine performance in the same way. However, he mostly used it to record past performance rather than looking ahead.

In 1914, the US army asked Gantt to help them resolve a major production network issues they were facing at the time with war supplies. This was essentially a synchronisation issue across a major supply chain, which helped Gantt realise the importance of time. He adapted his chart in order to focus on time instead of production output and compare planned work with actual work achieved. He used also specific visuals to highlight specific issues that were causing delays and identify particular patterns that required management intervention. Essentially this form of graphic schedule was the predecessor of what project managers use today. However, Gantt, despite his prolific work, has no reference to projects.

Focus only on efficiency

Due to its scientific management roots, the Gantt Chart is overly focused on efficiency and maximising the amount of work completed over a period of time. It considers scope as pre-defined and stable, while there is no reference to customer value, cost, quality, people, innovation, learning or any other variable.

During WWI, the problem that the US army was facing was schedule coordination and meeting the production volumes. There was abundance of people and of material resources. Gantt didn’t have to face any of the constraints that modern businesses do. The whole focus was on scheduling and sequencing.

In addition, due to the temporary nature of projects, the time-focused Gantt Chart became a very attractive tool for project managers. However, its excessive focus on time influenced negatively the project management profession, making schedule monitoring the top criterion of success. But many product development projects nowadays are more focused on customer value rather than time.

Of course, time can be an important parameter. But letting a tool, initially designed to optimise US Army supplies in WWI, to still dominate our thinking a hundred years later just doesn’t make sense. Furthermore, making time the key driving parameter is dangerous when engineers start cutting corners to deliver on time. Successful project management requires balance across multiple parameters.

There is only one best way of doing things

Following the principles of scientific management, the Gantt Chart assumes that there is a best way of executing a project. As such, its bars aim to represent an accurate description of how long every task takes and in which order to complete them.

Moreover, Gantt charts are put together by project managers who dictate in a top-down fashion who does, what, when and in which sequence. Project team members become irrelevant in the planning discussion, and are only there to execute the work. Essentially, the Gantt Chart becomes a project plan but with all the uncertainty removed. All time estimates, and predictions, are considered as facts waiting to happen. And this is where things start to break down.

Powerful executives and other stakeholders usually influence the initial project plan to make their projects look more attractive and get the right funding. As Professor Flyvbjerg has shown in his extensive research, most project estimates are overly optimistic, and this is due to political reasons. Essentially the Gantt Chart becomes a political tool.

Even worse, we tend to assume that the baselined plan is reliable. No-one challenges the baseline. Everyone automatically assumes that the baseline is optimal and everything just filters through it. Unfortunately, using tools like MS Project, only increases the illusion of accuracy, and makes people challenge even less the validity of the plan. As a consequence, the role of the project manager reduces to managing the deviations from the baseline, instead of finding alternatives way of progressing the work or harnessing the collective intelligence of the team.

Personally, I cannot think of a more mindless and irresponsible approach to managing work.

The future can be fully predicted (or not)

Another major principle behind the Gantt chart is determinism. It assumed that we can predict the future by analysing, defining, and recording the best way of performing each task. Since there is a best way of doing things, there is no uncertainty and the planning phase always comes separately before execution.

However, I talked earlier how there are acts, which are within our control, and events (risks) that fall completely outside of our control. Nevertheless, the Gantt chart simply takes uncertainty out of the equation, knowingly ignoring all of the unknowns. In a way, the project manager becomes the oracle that foresees and even controls the future.

Obviously, today this approach is not acceptable by any business, and risks are accepted as a fundamental part of life. Yet, we mindlessly use Gantt charts which are fully ignoring them by design! Even worse, the beginning of a project is the worst time to create and baseline plans, as it is usually plagued by political games between stakeholders, there is no team in place. while most people know very little about the complexity of the work or the risks involved.

Local optimisation of tasks instead of global

The Gantt chart assumes that any program of work can be broken down into specific tasks with pre-defined durations. It follows the reductionist thinking that a complex system is the sum of its parts or in this case a complex project is the sum of its tasks.

Furthermore, it assumes a division of labour, with people being accountable for a specific task. Everyone is replaceable with no influence on the performance of the tasks, as there is only one best way of doing them. When a task doesn’t finish on time, there is blame only on the person working on the task.

Unfortunately, this industrial view of the world is not only over-simplistic but also dangerously naive. By driving local optimisations, it leads to global inefficiencies. Instead of seeing the whole, it turns every task into a silo, which is then linked to other silos through dependencies. To make matters worse, a person is put to centrally manage dependencies, following a central planning, top down approach. This has led also to a fragmentation of the project management profession with a different person specialising in risk management, another one in planning, and another one in budgeting.

However, in the last 40 years with the development of systems thinking across multiple disciplines there has been a major paradigm shift. Teams, organisations, and anything that involves humans are now better described as Complex Adaptive Systems rather than a machine. In Complex Adaptive Systems, the whole is greater than the sum of its parts. This means that there are emergent properties that cannot be explained through analysis of the constituent parts but rather through understanding of how everything interrelates into a greater whole.

Projects seen as a production line (Waterfall approach)

Gantt Charts assume a linear approach. One task finishes for the next one to start. Work moves through sequential phases that lead to the final outcome. In addition, every task has a percentage of completion to convey progress based on elapsed time. The whole process resembles an industrial production line where the work moves from station to station in a linear fashion.

The assumption is that there is no learning feedback loop throughout the project. Everything should be right first time, and any lessons learned need to happen at the end of the whole project. This is quite a monolithic approach and ignores the fact that most learning happens evolutionary. It is practically impossible to know the best way of doing something upfront, especially when it comes to knowledge work. But even in modern day manufacturing nothing is fully predetermined and innovation is part of the process.

In reality things are almost never sequential, and this is where the Gantt Chart starts to break down. Of course, you may have experience of Gantt charts that have more network dependencies than just Finish-to-Start. But this is a later development which tries to adapt a production line tool to the messy world of knowledge work. Of course, this has ambiguous results that lead people away from these charts. This is why in the last 20 years most companies globally and across different industries are using Agile ways of working, emphasising the human side of things.


Human endeavour is so much more than industrial efficiencies, and obsessing about time. Furthermore, there are fundamental conceptual differences between planning and forecasting. The former is a statement of intended actions in order to influence the future in a beneficial way while the latter is a pure guessing game based on unverified assumptions and extrapolations from past events. Unless we realise this subtle difference we will keep confusing plans for forecasts, and project managers with oracles.

I can understand why Gantt and Taylor viewed the world as a machine and humans as replaceable cogs. After all, they spent their whole careers in 19th century steel mills and factories. But the world has moved on since then. There is absolutely no reason for us to carry on with this outdated paradigm in the 21st century, only because we assume that what we found before us is right. It is time to start challenging our assumptions and not let an outdated chart define how we work, collaborate, and achieve great things.

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