Safe fire exists may be easy but predicting human behaviour isn’t


By Lee Coates

Designing steel glazing systems to provide safe evacuation routes in a fire or terrorist incident is paramount. While providing those safe exits remains fundamental to fire and building safety, human behaviour in an emergency situation can also be an important factor.

Building safety is largely determined by taking a multi-disciplinary approach to assessing hazards – from power failure to cyber attack, from civil disorder to fire and explosive detonation – and arriving at risk assessments that illuminate how that building should be designed, built or managed. However, psychology is also a potent element. Evacuation models, based on engineering and computational tools, have been used for some time to estimate the time taken to evacuate a building. These models, particularly for larger or more complex buildings such as hospitals, are a requirement of fire safety and building approval. But research at the US National Institute of Standards and Technology (NIST), among others, demonstrates that those computer models don’t necessarily reflect the variable nature of human reaction. Assumptions can be built into the evacuation model that are too optimistic or, at the other end of the scale, too conservative, leading to additional risk or cost. In other words, computer modelling can only take us so far in designing in safety. What is also needed is an understanding of human behaviour in an emergency situation, particularly the factors that have been shown to influence our decision-making processes. By understanding those factors and processes, a fire safety team can develop a more comprehensive – and predictive – behaviour model for a building’s fire evacuation.

It all seems deceptively simple. A fire alarm sounds in an office building and everyone reacts promptly, only using designated stairways and exits, and making their way outside in a brisk but orderly manner. That is how a computational model might simulate a fire situation. But it doesn’t consider what is termed ‘exit choice behaviour’ – the different exits that people will choose to leave by, often because they’re also the entrances and routes by which they arrive at work.

Nor does it model ‘pre-movement times’– the golden period immediately following a fire alarm, when the fire has been detected but doesn’t yet pose a threat. Some members of staff will assume that it’s yet another fire alarm test. Others will assume that it’s a false alarm, maybe because they’ve happened before. Others will choose to ignore it because they’re making an important telephone call, or may have mobility problems. Others might not want to appear fearful in front of colleagues.

The psychology at work is that a fire alarm in itself is not necessarily regarded as an immediate call to action. It may be an alarm, but it’s not alarming. The alarm may have sounded, but no threat is apparent. Read More