A Review of Building Evacuation Models - NIST Virtual Library

Table A.12: Building/Occupant characteristics and the corresponding time effects
Building/Occupant Characteristics ΔT det *
(min)
ΔT rec
(min)
ΔT res
(min)
ΔT move
(min)
Only one available exit 2.5
Bad layout/geometry of occupancy area 5
Bad layout/geometry of escape routes 2
Unfamiliarity to building 5 5
Not alert (sleeping and/or drunk) 5 5
Social affiliation (family) 2
Social role (customer, visitors, worker, etc.) 5
Unclear visual access of exits from occupancy area 1
*Where “det” refers to detection, “rec” refers to recognition, and “res” refers to response.
77, p. 676
Occupant movement: ALLSAFE was developed to calculate evacuation scenarios where the
occupants are not aware of the fire until later in the situation. The main calculation is estimating
delay time of the occupants prior to evacuation. The model also includes a function to estimate
the walking time of the occupants. ALLSAFE defines the “minimum time of movement” or
“unimpeded time” (no behavioral delays) and this time is determined by flow calculations. The
developer admits that these calculations are simplified and also recommends the use of more
advanced flow models to determine the minimum movement time whenever movement is
critical. After determining the minimum movement time, an ALLSAFE database is used to add
delays and subtract reduction in evacuation times due to different kinds of safety measures, such
as alarm systems, staff guidance, unfamiliarity, immobility, social affiliation, signage, etc. The
final result obtained from the model is the “necessary time to evacuate.”
The model developers state that the input data affects all aspects of the evacuation process, based
on the study of recognized literature on the interaction of behaviour of evacuation and the fire in
actual fire incidents. The developers also state that assigned delay or pre-movement times are
based on real life evacuation experience. From the write-up on ALLSAFE, it seems that the
functions of the model based on actual incidents were determined through studies made by
SINTEF on large fire incidents. No further information is given as to the kinds of incidents
studied or the evacuation knowledge gained from these studies.
Output: The data obtained from the output is the following (for the entire population):
• Time to fire detection
• Time to react to the fire detection by the occupants
• Time to interpret the situation by the occupants
• Time to decide where to escape by the occupants
• Time to evacuate a room or corridor
• Time to evacuate the building
Use of fire data: The fire scenario can be calculated by fire models, such as FAST (listed by the
ALLSAFE write-up) or default values for the scenario can be chosen from ALLSAFE.
Import CAD drawings: No, this building is input by specifying nodes within the node structure
with the following information: minimum clearance width, walking distance to next node, initial
number of occupants in node, and the area of the node.
A-60