Safety Moment #62: From Complicated to Complex

In any performance-based program such as process safety, the work is never finished — there is always room for improvement.

In practice, most of the developments in techniques for improving safety analysis are improvements of existing programs or techniques. For example, the hazards analysis technique LOPA (Layers of Protection Analysis) has seen widespread application in recent years. Yet it is basically a development of the well-established Fault Tree and Event Tree techniques.

In order to understand how to develop more innovative ways of improving safety it is useful to distinguish between the words complicated and complex.  Most safety work has been to do with complicated systems — the opportunities for major improvements lie with understanding complex systems.

A complicated, not complex, system
A complicated, but not complex, system. Credit: Shutterstock


Process facilities consist of thousands of items that are connected to one another and that interact with one another. Yet, in spite of their size they are fundamentally understandable and predictable. They are complicated, not complex.

Most process safety work aims to understand and control this complication. The aim is to develop solutions that are both successful and repeatable. For example,

  • Once a method for writing operating procedures has been developed, then that method can be used throughout the organization for writing procedures for all types of facility and activity.
  • Once a hazards analysis team has identified how a pressure vessel may rupture they can apply that insight into the operation of all other pressure vessels.
  • Once an effective technique for analyzing incidents has been developed, that technique can be used for all future incident investigations.

Key words here are ‘understandable’ and ‘repeatable’. 

The following are features of complicated systems.

  • It is and can be understood by breaking it down into smaller parts, by determining how those parts work and how they interact with one another.
  • A complicated situation can be quantified and understood through the use of metrics.
  • A command and control management structure is effective at managing complicated systems.

By and large process safety professionals aim to reduce the risk associated with complicated system. And, on the whole, their efforts have been successful. Process facilities are more complicated than they were a generation ago — but the complication is understood and it is successfully managed.


A complex system is based on relationships, interconnection and evolution. It is fundamentally unpredictable. (Any system which involves human behavior — particularly the behavior of people in groups — will be complex.)

Complex systems do not have to be complicated — although most are.

Key aspects of a complex situation include the following.

  • It comprises relationships that cannot be understood just by breaking a system into its component parts.
  • The situation is fluid — surprises happen.
  • Command and control structures will be limited in their effectiveness.
  • It cannot be easily quantified — there are no effective metrics.
  • It will usually involve the unpredictable behavior of human beings, both as individuals and in groups.

Climate change is an excellent example of a complex system. Climate change models are increasingly accurate at forecasting what the climate will look like in coming years. But factors such as the following cannot be effectively modeled by a computer program.

  • The response by people, both as individuals and as part of larger groups such as nation states.
  • The impact of resource depletion. For example, if oil supplies start to dwindle, will the amount of CO2 being pumped into the atmosphere go down? Or will reduced oil supplies lead to increased coal consumption, thus increasing the amount of CO2 generated?
  • The impact of increased methane emissions from the tundra as permafrost melts.
  • The success or failure of efforts to reduce population growth.

The upshot of this way of thinking is that we learn that we cannot “solve” the climate change “problem”. Indeed, we don’t even know what the “problem” is. Instead, complexity creates predicaments or dilemmas. When faced with a predicament we can respond and adapt, but we cannot make it go away. We cannot return to the status quo pre ante. Nor can we predict what the future holds. There are surprises in store.

Process Safety Management

So where does this discussion take the discipline of process safety management?

If we are to manage complex situations effectively issues such as the following should be considered.

  • Notice new and unexpected emergent directions
    Not all events are predictable; adapt appropriately to unexpected situations.
  • Learn from new experiences
    Learning, in this context, is quite different from training or from education. It is based on an understanding that unexpected events will happen and the need to figure out why.
  • Factor in the vagaries of human behavior
    Regular readers of these Safety Moments know that, of all the elements of a process safety management system, the one that I regard as being the most important is Employee Participation. The catch is that people are inherently unpredictable. For example, an Asset Integrity program may be able to predict with a high level of confidence when an equipment item may fail. But no process safety program can predict if and when the workforce will initiate industrial action. Nor can the program anticipate that the maintenance technician will repair it incorrectly because his mind distracted due to a domestic conflict.

You are welcome to use this Safety Moment in your workplace. But please read Use of Safety Moments.

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