A Review of Building Evacuation Models - NIST Virtual Library

A.22 EXIT89
Developer: R.F. Fahy, NFPA, U.S.
Purpose of the model: EXIT89 was originally developed to simulate large populations in highrise
buildings 92-97 . The developer claims that the model is capable of the following things:
• Handle large populations
• Recalculate exit paths after nodes become blocked by smoke
• Track individual occupants as they move throughout the building
• Vary travel speed as a function of population density.
Availability to the public for use: The program has not been released by NFPA. The model
can be obtained through special arrangement with the developer. Currently, the model is not
publicly for sale.
Modeling method: This is a partial behavior model. It relies on the density versus speed data
from Predtechenskii and Milinskii for different building components, such as horizontal
components, doorways, up stairs, and down stairs. It also uses conditional movement, depending
upon the presence and density of smoke in the evacuation path.
Structure of model: This is a coarse network system. The floor plan is divided up into nodes
and arcs, specified by the user of the program. The nodes require the following input from the
user: the node name, the usable floor area, the height of the ceiling, maximum capacity of the
node (number of people), number of people at the node when evacuation begins, the number of
people at the node who are disabled, an ID that notes whether the node leads to the outside or is
part of the stairway, amount of time the people at that node will delay before evacuating, and the
node that occupants at that room will travel to if the user is defining the exit route. For each arc,
the distance from the first node to the opening/restriction between the two nodes, the width of
the opening, and the rest of the distance from the opening to the second node is specified.
Perspective of model: The model views the occupants individually because the output of the
model tracks the individuals’ positions throughout the evacuation. Also, the occupants have an
individual view of the building because the route choice can consist of either the shortest route
or a user-defined route for certain nodes. There is a fine line here because the individual
occupants are not given a route. Instead all occupants located initially at a certain node will
travel the user-defined route. If an exit is blocked manually or by smoke conditions, the
occupant then chooses an alternate route based on the floor they are on, not a global view of the
building. This way, the occupant may take a longer way out 97 .
Occupant behavior: Implicit behavior is modeled.
Occupant movement: The model emulates the “shortest route” algorithm that identifies the exit
of the network and then fans out from the exit in an attempt to identify the shortest routes to all
other nodes. EXIT89 calculates the shortest routes on each floor to the stairs or outside. This is
A-78