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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A.19 EGRESS<br />
Developer: N. Ketchell, AEA Technology, UK<br />
Purpose <strong>of</strong> the model: The purpose <strong>of</strong> this model is to determine the evacuation <strong>of</strong> crowds in a<br />
variety <strong>of</strong> situations, such as theaters, <strong>of</strong>fice buildings, railway stations, and ships 11, 82-84 .<br />
Availability to the public for use: EGRESS is available only on a consultancy basis and the<br />
s<strong>of</strong>tware is not <strong>of</strong>fered for sale.<br />
Modeling method: This is a behavioral model<br />
Structure <strong>of</strong> model: This is a fine network system. The floor plan <strong>of</strong> a building is covered in<br />
cells that are equivalent in size to the minimum area occupied by an occupant. Instead <strong>of</strong> being<br />
square, like most grid cells, the cell is hexagonal in shape, as shown in Figure A.22. The<br />
2<br />
hexagon has a height equal to h and an area <strong>of</strong> 3 2 × h . EGRESS holds a default <strong>of</strong> 5 people<br />
per square meter, which equals a grid spacing <strong>of</strong> 0.5 m. This can be modified if occupants are<br />
expected to be carrying large objects, etc.<br />
Figure A.22: Example <strong>of</strong> cells on an egress plan<br />
84, p. 2<br />
Perspective <strong>of</strong> model and occupant: The model views the occupants as individuals. The<br />
movements <strong>of</strong> each occupant are carefully monitored throughout the simulation. Each individual<br />
also has certain goals and a specified time period to complete that goal.<br />
The occupants’ perspective <strong>of</strong> the floor plan is also individual. EGRESS contains a route finding<br />
algorithm that defines the shortest distance from each cell on the floor plan to each specified<br />
region or exit. Then, the behavioral modeling aids in choosing which objective the occupants<br />
moves toward.<br />
Occupant behavior: The occupant behavior is conditional. As long as the objective is still<br />
possible within the time frame allotted, the individual continues to pursue the goal.<br />
The method <strong>of</strong> behavioral modelling has become simpler since the previous method was found to<br />
cause major issues in the number <strong>of</strong> decisions made by each occupant. EGRESS provides<br />
groups <strong>of</strong> occupants with itineraries throughout the evacuation in order to alter objectives/goals,<br />
as shown in Figure A.23. Each objective (example is movement towards the fire for an<br />
A-66