Civil Engineering Reference
In-Depth Information
There are of course a number of factors which
impact upon the fl ow rates of a crowd including:
In situations where there are large numbers of
people or people are within large spaces, e.g. shopping
malls, their behaviour is shaped by a number of factors
including the following.
Spatial awareness
- the degree to which people are
able to orientate themselves in unfamiliar surroundings
will affect their choices of action in the event of a fi re. It
is generally accepted that people will leave a building by
the route they entered irrespective of the availability of
closer alternative exits.
Smoke movement
- there have been instances
where the movement of smoke within shopping malls has
given the false impression that the fi re is in one particu-
lar direction. It is understandable that people will want
to move away from the perceived seat of the fi re which
has resulted in them moving towards the fi re rather than
away from it.
Ergonomics
- despite the adequacy of the means
of escape (size, travel distance) unless it is laid out in a
way that people can easily understand and signed in a
consistent and logical manner it will slow the evacuation
of a building. In order to encourage people to evacuate
within a reasonable time the means of escape must
refl ect good ergonomic principles in such a way that
evacuating a building becomes intuitive.
➤
The clarity of the indication of the direction of travel
➤
Any apparent sign of fi re
➤
Degree of perceived urgency of the evacuation
➤
The lighting levels
➤
The underfoot conditions
➤
The characteristics of the crowd, i.e.:
➤
Age
➤
Mobility
➤
Alertness, etc.
Traditionally fl ow rates have been calculated from histor-
ical data and these are now being reviewed in the light
of electronic data gathered from computer simulation.
The more information individuals have about a fi re emer-
gency the greater their ability to respond appropriately.
However, infl uences also include the provision of appro-
priate design arrangements for areas such as crèches
within public buildings, e.g. sports centres.
Crowd dynamics will be directly affected by parents
and guardians wishing to ensure that their charges have
left the building and it is likely that they will not rely upon
the attendants or nursing staff.
Figure 10.12
Manchester airport fi re involving an aircraft on the runway - A quickly developing fi re in an enclosed space
which resulted in an urgent need to escape and reduced evacuation time
