A Review of Building Evacuation Models - NIST Virtual Library

Occupants can also be introduced into the simulation at a certain time and place, after the
evacuation has begun. When family groups are specified in STEPS, the family moves
throughout the simulation to meet at a certain position in the building before evacuating.
Output: STEPS output includes the total evacuation time, numbers of occupants in certain
areas, planes, paths, and the entire simulation and the number of people that have left these
different fields vs. time.
Use of fire data: None.
Import CAD drawings: Yes, CAD drawings are input in DXF file format.
Visualization capabilities: 3-D visualization.
Validation studies: STEPS
simulations have been compared to
the method of evacuation
calculations outlined by NFPA
130 21 . This report outlines two
examples that demonstrate STEPS’
applicability to station geometries.
The first case, shown in Figure A.6,
involves a center-platform station in
which the platform is raised above
the concourse (at grade level) as
shown in the figure. By using the
NFPA calculations for Case 1, the
total time to clear the platform is
190.7 s and the total time to
evacuate the station is 239.9 s.
21, p. 130-30
Figure A.6: Case Study 1
When the identical model of this station is simulated with STEPS, the mean time to clear the
platform is 212.4 s and the mean evacuation time is 257.4 s. This case shows a difference of 7.3
% to 11.4 % between NFPA 130 and STEPS. Also, STEPS is able to model the natural
imbalance of exit use, while NFPA 130 calculations assume that all exits are used optimally.
Case 2 involves a more complex station with a side-platform. As shown in Figure A.7, the
concourse is below grade level and the platform is below the level of the concourse. Using
NFPA 130, the total time to clear the platform is 179.8 s and the total evacuation of the station is
369.8 s. Also, when recalculating NFPA evacuation times using a different, more realistic split,
the result is found to be 306.3 s. When modeled in STEPS, a mean platform clearing time of
181.4 s is achieved and a mean total evacuation time was 313.2 s. This shows a 0.9 % to 2.3 %
difference between STEPS and NFPA 130 calculation methods.
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