In other words, human behaviour can sometimes work against
the fast evacuation of a building, whose evacuation models are
often based on engineering and computational tools. However,
research at the US National Institute of Standards and Technology
(NIST), among others, demonstrates that those computer models
don’t always take human reaction into consideration.
After all, we’ve all been in a building when a fire alarm has
sounded. Did you immediately move towards the nearest exit?
Probably not. Our first instinct is not to take the alarm too
seriously. We can’t see any smoke or flames. We can’t smell
smoke. It must therefore be a fire test or a false alarm. Until we
know for certain, we do nothing.
That period is called “pre-movement time” – the period when
nothing much happens. Psychologically, our brains are telling us
to think logically. There is no discernible threat, the chances of it
being a real fire are remote and, frankly, I’m composing a rather
important email to my boss in Bradford.
In most cases, therefore, a fire alarm isn’t in itself a call to action.
More often, it’s a source of confusion because, even when we
believe the alarm might be real, we don’t know where the threat
is coming from. This also adds to a delayed evacuation because
none of us wants to evacuate until we know that our escape route
is safe.
The fire alarm therefore precipitates a variety of responses. Some
people will take it seriously; others will wait until they have more
information. Some will seek guidance from co-workers or their
superiors; some will ignore it completely. It’s estimated that as
much as two-thirds of the time it takes people to exit a building
after an alarm is start-up time – time wasted in looking for more
information.
And then there’s “exit choice behavior” which computational
models can also struggle with because, again, human nature
comes into play. We don’t always exit a building by designated
routes. We’ll exit a building by the route we’re familiar with, even
it’s a longer journey – for example, the route by which we arrive
at our desk in the morning.
All of those factors, and many others, can influence the level of
protection that should be applied within a particular building. It’s
not just about using a computer model to estimate how long a
well-drilled evacuation will take. It’s also about adding in human
behavior.
And that’s why our advanced steel glazing systems provide up to
120 minutes of fire resistance, containing fire away from escape
routes, and giving everyone, even the most complacent or stupid,
more than enough time to escape.
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The most tragic example was 9/11, when fewer than 9% of
the occupants of the World Trade Center towers immediately
evacuated after the alarms sounded. The average “start up”
time before people began to move to the exits was between five
and eight minutes. Others didn’t start to evacuate for up to 40
minutes.
But behavior isn’t just about us as individuals. Groups of people
can influence one another. People want to evacuate alongside
colleagues, slowing evacuation down to the speed of the slowest
person. In a shopping centre, we might be evacuating with elderly
relatives or small children.