Civil Engineering Reference
In-Depth Information
A
C
D
B
C
A
x
E
B
D
E
A - B = Stage 1
B - C = Stage 2
C - D = Stage 3
D - E = Stage 4
Place of safety outside
at ground level
Figure 9.26
Component parts of an escape route
*
stairs
3
1 & 2
stairs
Figure 9.27
The stages of escape in open planning
Figure 9.26 illustrates the four stages of escape in a com-
mon traditional building layout. Whereas Figures 9.27
and 9.28 show how the various stages of escape in open
planned and cellular planned internal layouts are applied.
In buildings with simple internal layouts, the stages
are relatively easy to identify. However, in more complex
buildings where there may be phased evacuation, for
example, Stage 2 may only be to a place of safety on
the same level, referred to as a 'refuge'.
In high-rise buildings it may not be practicable or
desirable to commence total evacuation so the design
must allow for a phased evacuation. Structural elements
and internal fi re systems must have suffi cient resilience
to restrict fi re spread, so that people most at risk can
evacuate fi rst, while others can be evacuated later, once
the fi re fi ghting teams arrive.
This type of scenario clearly demonstrates the
interaction of escape, containment and extinguish-
ment, with communication in the central role. Phased
evacuations may go through Stages 1 and 2, with Stage
3 held in reserve, or Stages 1 to 4 (the total evacu-
ation) of some occupants while others are put on 'alert'
in readiness for evacuation and moved to safety when
practicable.
Stage 1 Travel - from the room of origin
When considering escape from a room, the speed of
fi re spread needs to be considered and compared with
