A Review of Building Evacuation Models - NIST Virtual Library

Lastly, Fahy simulated a fire drill conducted in a major department store by the University of
Ulster in the UK. 495 occupants were involved, many of whom were video taped and
interviewed about their evacuation. Travel speed that would provide the longest and most
conservative evacuation times (normal evacuation speed) were used, due to the lack of cues
indicated an emergency. Also, the shortest route option was selected for the occupants because
of the presence of staff during the evacuation. The model simulation incorporated delay times
for occupants recorded on videotape, as well as mean delays times for each department and
additional random delays for each occupant. Table A.15 below shows the results for the
observed and simulated evacuations from the department store:
Table A.15: EXIT89 validation study results from the department store
Observed
Predicted
Exit # People First (s) Last (s) # People First (s) Last (s)
1 33 23 83 45 28 64
2 52 31 165 85 43 71
3 32 36 100 16 22 49
4 49 1 104 80 33 83
5 77 17 95 36 39 52
6 41 21 153 26 37 49
7 2 - - - - -
8 23 33 78 23 47 85
9 23 26 119 27 42 111
10 7 50 78 27 37 106
11 6 46 60 5 45 54
12 58 32 119 13 49 83
13 45 14 85 49 31 104
14 29 34 102 63 37 74
Total 495 495
As shown, the observed evacuation ended in 2 min, 45 s and the simulation ended in 1 min 51 s.
Fahy states that there was good agreement between the observed and EXIT89 results, and also
noted large discrepancies for Exits 2 and 6. Fahy explained these discrepancies as delays
prompted by the staff involving the deactivation of the door alarm, checking shopping baskets of
evacuees, and performing final sweeps of the area for stray occupants.
Special features:
Counterflow – Yes, the user specifies what percentage of the stairwell is blocked and at what
time within the simulation that this occurs. If the obstruction or counterflow disappears after
some time, the user can set the node back to its original area.
Manual exit block/obstacles – Yes, the user enters the name of the blocked node and the time
from the start of the evacuation that the blockage occurs (in s). Multiple nodes can be blocked at
one time.
Fire conditions affect behavior Yes, the user can enter the output from CFAST. EXIT89 uses
the smoke densities and depth of the smoke layer from CFAST to calculate the “psychological
impact of smoke, S.” This is done with the following equation: S = 2*OD*(D/H) where OD is
the optical density of the smoke layer, D is the depth of the upper layer, and H is the height of
A-81