A Review of Building Evacuation Models - NIST Virtual Library
A Review of Building Evacuation Models - NIST Virtual Library
A Review of Building Evacuation Models - NIST Virtual Library
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• Occupants stop investigating if they are in a room where S>0.05. They will stop<br />
investigating before entering a room where S>0.1<br />
• If the occupant is in a room where S>0.1, he/she will respond more quickly and believe the<br />
fire is more serious.<br />
• Penalties and demerits are assigned to a route where S>0.4<br />
The occupants are assigned certain characteristics for a simulation and those are age, sex, normal<br />
walking speed, whether or not the occupants have special needs, whether or not the person is<br />
sleeping, room location, and difficulty <strong>of</strong> waking up.<br />
There are two types <strong>of</strong> occupants within the model, those fully capable when awake and those<br />
who are in need <strong>of</strong> assistance to evacuate the building. Decision rules apply only to the first<br />
group, and the latter group only follows those decisions and movements made by their rescuers.<br />
Capable occupants become aware <strong>of</strong> the fire through cues, such as the sound <strong>of</strong> a smoke<br />
detector, odor <strong>of</strong> smoke, visible smoke, and visible flame. The model follows a basic equation<br />
for if and when an occupant will begin responding to a cue, and suggests the work <strong>of</strong> Nober 65 is<br />
the formulation <strong>of</strong> this equation. Equation A.4 is the cue equation, which assumes that the<br />
occupant’s response is a function <strong>of</strong> the sum <strong>of</strong> impacts from sensory cues:<br />
T = 70 – 4(C-20) and C = (A-N) + X 1 + X 2 + X 3 + X 4<br />
(A.4)<br />
where T is the delay time before beginning the first action, C is the sum <strong>of</strong> sensory impacts on<br />
the occupant, A is the sound intensity <strong>of</strong> the smoke detector as heard by the occupant, N is the<br />
background noise, X 1 is the impact <strong>of</strong> an occupant seeing flame, X 2 is the impact <strong>of</strong> the occupant<br />
smelling smoke, X 3 is the impact <strong>of</strong> an occupant seeing smoke, and X 4 =0 if occupant is sleeping<br />
and 15 if the occupant is awake. X 1 and X 3 = 0 if the occupant is asleep.<br />
EXITT normally assigns investigation as the first action <strong>of</strong> the occupant. Exceptions to this<br />
include if an occupant has completed investigation, if there is bad smoke in the room, if the<br />
occupant has been alerted by another who has seen bad smoke, or if the occupant is an adult<br />
female with an infant that needs help. The occupants have other alternative actions in the case<br />
that the exceptions apply (in this specific order) which are help an occupant in the same room,<br />
help an occupant in a different room, investigate, and egress. Occupants over age 10 act in the<br />
same way as an adult would.<br />
Any delay time, decision time, and time to perform actions depend on the occupant<br />
characteristics, fire environment, and the impact <strong>of</strong> the fire cues onto the occupants.<br />
An addition to the model includes the option for users to override the decision rules and study<br />
the effect <strong>of</strong> alternative decisions.<br />
Occupant movement: As mentioned earlier, a normal walking speed is assigned to each<br />
occupant by the user, and throughout the simulation, speeds are altered in the following way:<br />
• 30 % faster than normal if the occupant considers the fire to be serious<br />
A-46